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  • 1.
    Agthe, Michael
    et al.
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Wetterskog, Erik
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Salazar-Alvarez, German
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Bergström, Lennart Magnus
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Dynamic growth modes of ordered arrays and mesocrystals during drop-casting of iron oxide nanocubes2014Ingår i: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 16, nr 8, s. 1443-1450Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The growth modes of self-assembled mesocrystals and ordered arrays from dispersions of iron oxide nanocubes with a mean edge length of 9.6 nm during controlled solvent removal have been investigated with a combination of visible light video microscopy, atomic force microscopy and scanning electron microscopy. Mesocrystals with translational and orientational order of sizes up to 10 μm are formed spontaneously during the final, diffusion-controlled, drop-casting stage when the liquid film is very thin and the particle concentration is high. Convection-driven deposition of ordered nanocube arrays at the edge of the drying droplet is a manifestation of the so called coffee-ring effect. Dendritic growth or fingering of rapidly growing arrays of ordered nanocubes could also be observed in a transition regime as the growth front moves from the initial three-phase contact line towards the centre of the original droplet.

  • 2.
    Aguilar, Wilson
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Study of the Synthesis of ZSM-5 from Inexpensive Raw Materials2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    ZSM-5 is an aluminosilicate with high silica ratio with suitable properties for catalysis, ion exchange, adsorption and membrane applications. ZSM-5 is usually produced industrially from concentrated systems in which there is formation of an amorphous gel phase. Typical syntheses of ZSM-5 require sources of silicon and aluminium, a mineralizer and an organic molecule as so-called templating agent. The silicon and aluminum sources widely used for the synthesis are pure reagent chemicals and in particular quaternary ammonium compounds like tetrapropyl ammonium hydroxides (TPA-OH), are employed as templating agents. Unfortunately, these compounds are rather expensive. Demand for inexpensive sources of aluminosilicates for the synthesis of ZSM-5 has increased during the last two decades. Natural raw materials such as kaolin clay and diatomaceous earth (diatomite) are two potential inexpensive sources of silica and alumina. Moreover, the molecule n-butylamine (NBA) has been reported as a low-cost templating agent to replace the quaternary ammonium compounds. The aim of this work was to show for the first time that leached metakaolinite or diatomite in combination with sodium hydroxide and n-butylamine could be used as inexpensive raw materials for the synthesis of ZSM-5 without using an additional source of silica. After synthesis optimization, both sources of aluminosilicate were found to behave differently during the course of synthesis and led to slightly different products. The chemical composition of the raw materials and the products were determined using inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). Crystallinity was examined by X-ray diffractometry (XRD), the morphology was studied by extreme-high-resolution scanning electron microscopy (XHR-SEM) and the specific surface area was estimated from nitrogen adsorption data by the BET method. The chemical composition of individual crystals was determined by energy dispersive spectrometry (EDS). Dealumination of the raw materials by acid leaching made it possible to reach appropriate SiO2/Al2O3 ratios and reduced the amount of impurities. The final ZSM-5 products had a SiO2/Al2O3 ratio in the range 20 – 40. The use of leached diatomite allowed reaching higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of mordenite were formed, which was related to the high calcium content of diatomite. Another considerable advantage of diatomite over kaolin is that diatomite does not require heat treatment at high temperature to convert the kaolin to reactive metakaolin. Further characterization of the system by XHR-SEM and EDS at low voltage was carried out in order to understand the nucleation and early growth of the ZSM-5 zeolite crystals. The observations with unprecedented detail strongly suggest that nucleation and the succeeding growth occurs on the gel surface. The growth rates in the various crystallographic directions already at an early stage are such that the shape of the growing crystals resembles that of the final crystals. However, as the early growth is interface mediated, the growth rate along the gel particles is high and the gel particles will become partially embedded inside the growing crystals at an early stage. The Si and Al nutrients are probably transported along the solid/liquid interface and possibly through the liquid in the form of nanoparticles detaching from the gel. The organic template was initially contained in the liquid. However, it remains unclear at which stage the template becomes incorporated in the solid material. EDS at low voltage was also used to gain compositional information about the sodium/calcium ion exchanged products and extraneous phases when kaolin and Bolivian montmorillonite clay were used for the synthesis of zeolite A by alkali fusion. In order to evaluate the cation exchange capacity (CEC) of the synthesized zeolite, ICP-SFMS and EDS were compared. The EDS method used in this work resulted in (Na,Ca)/Al ratios in equivalent moles very close to 1.0 as expected and was therefore found more reliable than ICP-SFMS to measure cation exchange capacity for zeolite A. To summarize, the present work shows that it was possible to synthesize well-crystallized ZSM-5 zeolite from inexpensive raw materials such as leached metakaolin or leached diatomite, sodium hydroxide and n-butyl amine. Furthermore, the crystallization mechanism evidenced in this system might be more general and also apply for other concentrated systems, e.g. those using TPA as structure-directing. Finally, this work displays that EDS at low voltage can provide valuable local compositional information in the field of zeolite synthesis.

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  • 3.
    Aguilar, Wilson
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Cardenas, Edgar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Dendritic growth of NBA-ZSM-5Ingår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Crystallization of ZSM-5 zeolite from a gel using n-butylamine as structure-directing agent was studied. Extreme high-resolution transmission and scanning electron microscopy showed the presence of dendritic features that are present at the crystal surface during most of the reaction time that become smoother towards completion of the crystallization. In addition, a web that likely stems from the gel, comprised of alumina-rich nanoparticles between the dendrites at the surface of the crystals was also identified. When the gel is not in direct contact with the crystal surface, dendrites and the web are not observed, and the crystals grow faster. Thus, the alumina-rich web retards the crystal growth and cause the formation of dendritic features.

  • 4.
    Aguilar, Wilson
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Garcia, Gustavo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Comparison between leached metakaolin and leached diatomaceous earth as raw materials for the synthesis of ZSM-52014Ingår i: SpringerPlus, E-ISSN 2193-1801, Vol. 3, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Inexpensive raw materials have been used to prepare ZSM-5 zeolites with SiO2/Al2O3 molar ratios in the range 20 - 40. Kaolin or Bolivian diatomaceous earth was used as aluminosilicate raw materials and sodium hydroxide and n-butylamine were used as mineralizing agents and template. Dealumination of the raw materials by acid leaching made it possible to reach appropriate SiO2/Al2O3 ratios and to reduce the amount of iron and other impurities. After mixing the components and aging, hydrothermal treatment was carried out and the products were recovered The results clearly show for the first time that well-crystallized ZSM-5 can be directly prepared from leached metakaolin or leached diatomaceous earth using sodium hydroxide and n-butylamine as mineralizing agents and template under appropriate synthesis conditions. A longer induction time prior to crystallization was observed for reaction mixtures prepared from leached diatomaceous earth, probably due to slower digestion of the fossilized diatom skeletons as compared with that for microporous leached metakaolin. The use of leached diatomaceous earth allowed higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of Mordenite formed, which was related to the high calcium content of diatomaceous earth. Another considerable advantage of diatomaceous earth over kaolin is that diatomaceous earth does not require heat treatment at high temperature for metakaolinization.

  • 5.
    Aguilar-Mamani, Wilson
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Crystallization of NBA-ZSM-5 from kaolin2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    ZSM-5 is an aluminosilicate zeolite with high Si/Al ratio with suitable properties for catalysis, ion exchange, adsorption and membrane applications. The main goal of this thesis was to study the growth of ZSM-5 zeolite crystals from inexpensive natural sources of silica and alumina, as well as n-butylamine (NBA) as a low-cost structure directing agent.

    The first objective of this work was to develop pathways to synthesize ZSM-5 crystals from kaolin clay or diatomaceous earth, two inexpensive natural sources of silica and alumina (Paper I). In the case of kaolin, a heat treatment was used in order to form amorphous metakaolinite. Subsequently, dealumination of the raw materials by acid leaching made it possible to reach appropriate Si/Al ratios and to reduce the amount of impurities. Finally, leached metakaolinite or diatomaceous earth was reacted with sodium hydroxide and NBA. After synthesis optimization, both sources of aluminosilicates were found to behave differently during the course of synthesis and to lead to slightly different reaction products. The final products exhibited Si/Al ratios in the range 10-20. The use of leached diatomaceous earth allowed to reach higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of mordenite were inevitably formed as a by-product, which was related to the high calcium content of diatomaceous earth. Therefore, the rest of the thesis focused on the kaolin system.

    In order to study the growth mechanism of ZSM-5 from leached metakaolinite, a proper methodology to gain local compositional data by energy dispersive spectroscopy (EDS) on aluminosilicates was developed (Paper II). Zeolite A was used as a model system that could be ion-exchanged with various elements. In order to evaluate the reliability of the measurements, inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) and EDS were compared. The EDS method developed in this work resulted in molar ratios very close to theoretical values and was therefore found more reliable than ICP-SFMS. Therefore, the method developed for zeolite A was applied in the rest of the thesis work to study the formation and growth of ZSM-5 crystals.

    The second part of this work focused on the kaolin system in order to understand the nucleation and growth processes of the ZSM-5 crystals. This system was heterogeneous, due to the formation of a gel upon heating of the synthesis mixture. First, the internal structure of the gel was investigated (Paper III). Second, a kinetic study was performed and compared with microstructural observations (Paper IV). Finally, the mechanisms leading to Al-zoning and dendritical growth of the zeolite crystals were investigated (Paper V). The characterization of the intermediate phases during the different stages of the hydrothermal synthesis were analyzed by different analytical techniques, such as inductively coupled plasma-sector field mass spectrometry (ICP-SFMS), dynamic light scattering (DLS), extreme high resolution-scanning electron microscopy (XHR-SEM), energy dispersive spectroscopy (EDS), high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) and nitrogen gas adsorption.

    These investigations led to several important conclusions: 1) The walls of the gel were shown for the first time to be inhomogeneous and to possess a biphasic internal structure consisting of a mesoporous skeleton of aluminosilicate nanoparticles embedded in a silicate-rich soluble matrix of soft matter. 2) The kinetic study and microstructural evidences indicated that the early crystals were fully embedded inside the gel phase and that crystal growth was retarded, as the formation of the gel occurred simultaneously with the early growth of the crystals. Hence, nucleation and growth appeared to be solution mediated.  3) Finally, the Al zoning of the crystals was related to the biphasic internal structure of the gel, since the silicate-rich matrix was preferentially consumed first. 4) The dendrites present at the surface of the crystals during most of the growth process were shown to be caused by the presence of a web of nanoparticles, most likely originating from the mesoporous skeleton inside the gel.

    In the future, these findings are expected to lead to optimized synthesis pathways of catalysts with homogeneous properties and to contribute to the development of poor regions in Bolivia.

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  • 6.
    Aguilar-Mamani, Wilson
    et al.
    Department of Chemistry, Faculty of Science and Technology, San Simon University, UMSS, Cochabamba.
    Akhtar, Farid
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Solution-mediated growth of NBA-ZSM-5 crystals retarded by gel entrapment2018Ingår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 487, s. 57-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The synthesis of flat tablet-shaped ZSM-5 crystals from a gel using metakaolin as aluminosilicate source and n-butyl amine as structure directing agent was investigated. The evolution inside the solid phase was characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry and mass spectrometry. A kinetic study indicated that the nucleation of the majority crystals occurred concurrently with the formation of the gel upon heating the starting liquid suspension. Microstructural evidences undeniably showed that the gel precipitated on ZSM-5 crystals and mineral impurities originating from kaolin. As a result, crystal growth was retarded by gel entrapment, as indicated by the configuration and morphology of the embedded crystals. The results presented herein are harmonized with a solution-mediated nucleation and growth mechanism. Our observations differ from the autocatalytic model that suggests that the nuclei rest inside the gel until released when the gel is consumed. Our results show instead that it is crystals that formed in an early stage before entrapment inside the gel that rest inside the gel until exposed at the gel surface. These results illustrate the limitation of the classical method used in the field to determine nucleation profiles when the crystals become trapped inside the gel.

  • 7.
    Aguilar-Mamani, Wilson
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Department of Chemistry, Faculty of Science and Technology, San Simon University, Cochabamba, Bolivia.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Internal structure of a gel leading to NBA-ZSM-5 single crystals2018Ingår i: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 25, nr 6, s. 1551-1559Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Porous gel structures are formed during the synthesis of the zeolite ZSM-5 due to the reaction between a source of aluminosilicate, sodium hydroxide, water and a structure directing agent, such as e.g. tetrapropylammonium (TPA) or n-butylamine (NBA). In the present work, the formation of the gel in a heterogeneous system leading to the crystallization of NBA-ZSM-5 zeolite from leached metakaolin was studied extensively. The solid and liquid phases obtained after separation were analyzed by inductively coupled plasma sector field mass spectrometry, dynamic light scattering, extreme high resolution-scanning electron microscopy, energy dispersive spectroscopy, high resolution-transmission electron microscopy, X-ray diffraction and nitrogen gas adsorption. The main gel phase formed after hydrothermal treatment exhibited a sponge-like structure resembling those forming in (Na, TPA)-ZSM-5-based systems. For the first time, the walls of the main gel were shown to be inhomogenous and to possess a biphasic internal structure consisting of a mesoporous skeleton of aluminosilicate nanoparticles embedded in a silicate-rich soluble matrix of soft matter. The data presented in this paper is of primary importance to understand the mechanism by which the gel is consumed and contributes to the growth process of the zeolite crystals.

  • 8.
    Ahmed, Hamzah
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Shimpi, Manishkumar R.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Velaga, Sitaram P.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol2017Ingår i: Drug Development and Industrial Pharmacy, ISSN 0363-9045, E-ISSN 1520-5762, Vol. 43, nr 1, s. 89-97Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objectives were to study mechanical properties of various solid forms of paracetamol and relate to their crystal structures. Paracetamol Form I (PRA), its cocrystals with oxalic acid (PRA-OXA) and 4,4-bipyridine (PRA-BPY) and hydrochloride salt (PRA-HCL) were selected. Cocrystals and salt were scaled-up using rational crystallization methods. The resulting materials were subjected to differential scanning solid-state characterization. The powders were sieved and 90-360 µm sieve fraction was considered. These powders were examined by scanning electron microscopy (SEM) and densities were determined. Tablets were made at applied pressures of 35-180 MPa under controlled conditions and the tablet height, diameter and hardness were measured. Tensile strength and porosity of the tablets were estimated using well known models. Crystal structures of these systems were visualized and slips planed were identified. Cocrystal and salt of PRA were physically pure. Sieved powders had comparable morphologies and particle size. The apparent and theoretical densities of powders were similar but no clear trends were observed. The tensile strengths of these compacts were increased with increasing pressure whereas tabletability decreased in the order oxalic acid > PRA-HCL ≈ PRA-OXA > BPY > PRA-BPY. Tablet tensile strength decreases exponentially with increasing porosity with the exception of PRY-BPY and BPY. Slip plane prediction based on attachment energies may not be independently considered. However, it was possible to explain the improved mechanical properties of powders based on the crystal structure. Cocrystallization and salt formation have introduced structural features that are responsible for improved tableting properties of PRA.

  • 9.
    Ahmed, Mukhtiar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Fluorine-Free Ionic Liquid Based Electrolytes: Synthesis and Structural Characterization2022Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Since their introduction by Sony in 1990, lithium-ion batteries (LIBs) have acquired a sizable market share. They have the best energy densities, a high open circuit voltage, a low self-discharge rate, no memory effect, and a slow loss of charge when not in use. These properties make them the most popular rechargeable batteries for portable gadgets, electric vehicles and aerospace applications.  They do, however, pose major safety issues since the electrolytes are made up of fluorinated salts dissolved in volatile organic solvents, the former being meta-stable at ambient temperature and the latter being flammable a with high vapour pressure. Thus, there is an urge to develop thermally and electrochemically stable non-fluorinated electrolytes to improve the safety and performance of batteries. Electrolytes based on ionic liquids (ILs) in general offer a range of suitable advantages including low volatility and high thermal and electrochemical stabilities,and can additionally be made fluorine-free. In general, their physicochemical properties are determined by the interactions between the cations and anions, which are controlled by the chemical functionalities present, with vast freedom in structural design to reduce these interactions and enhance also the ion mobilities. 

    In this study, favoring from of “structural design” three different families of fluorine-free ionic liquids-based electrolytes are designed and created. These families of ILs comprising n- tetrabutylphosphonium, imidazolium, pyridinium based cations and pyridine, pyrazine and ether functionalized salicylate-based anions. The structures and purity of these new ILs are characterized by using multinuclear NMR, FTIR and mass spectrometry. Several features and properties of the novel electrolytes are investigated; thermogravimetric analysis, differential scanning calorimetry, ionic conductivity and electrochemical stability. These studies are further complemented by using PFG NMR diffusometry to understand the possible interaction mechanisms between the oppositely charged ions within the electrolytes, and especially, the influence of Li+ addition in the IL-based electrolytes. 

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  • 10.
    Ahmed, Mukhtiar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Fluorine-Free Ionic Liquids and Electrolytes: From Synthesis to Energy Storage Applications2023Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Since their introduction by Sony in 1990, lithium-ion batteries (LIBs) have acquired a sizable market share. They have the best energy densities, a high open circuit voltage, a low self-discharge rate, no memory effect, and a slow loss of charge when not in use. These properties make them the most popular rechargeable batteries for portable gadgets, electric vehicles and aerospace applications. They do, however, pose major safety issues since the conventional electrolytes are made of fluorinated salts dissolved in volatile organic solvents, the former being meta-stable at ambient temperature and the latter being flammable with a high vapour pressure. Thus, there is an urge to develop thermally and electrochemically stable non-fluorinated electrolytes to improve the safety and performance of batteries. Electrolytes based on ionic liquids (ILs) offer a range of advantages over traditional electrolytes including low volatility and high thermal and electrochemical stabilities, and can additionally be made fluorine-free and task-specific. In addition, the transport properties of ILs can be controlled by structural design of chemical functionalities to reduce the ionic interactions and enhance the ion mobilities.

    This thesis is focussed on the development of new fluorine-free ILs and electrolytes for safer energy storage applications. An overview of synthesis, physicochemical and electrochemical characterizations of six different families of ILs and their structurally analogous electrolytes based on the aromatic heterocyclic rings, oligoether based aromatic and aliphatic carboxylates, oligoether phosphates and aromatic sulfonyl anions coupled with n- tetrabutylphosphonium-, imidazolium-, pyrrolidinium-based and alkali metal cations is presented. The structures and purity of the new anions, their intermediate products and the ILs are characterized by using multinuclear NMR, FTIR and mass spectrometry. These studies are further complemented by using NMR diffusometry to investigate the relative anion and anion mobilities and understand the possible interaction mechanisms between the oppositely charged ions within the ILs and the electrolytes, and especially, the influence of Li+ addition in the IL-based electrolytes. Among the synthesized ILs, the sulfonyl-based ILs revealed highest thermal stabilities, aromatic oligoether-based ILs showed the best electrochemical stabilities and aromatic sulfonyl -based ILs exhibited highest ionic conductivities. Some of the synthesized salts displayed promising performance as electrolytes in energy storage devices.

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    Publikationen är tillgänglig i fulltext från 2024-10-01 12:00
  • 11.
    Ahmed, Mukhtiar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Bhowmick, Sourav
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Filippov, Andrei
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Johansson, Patrik
    Materials Physics, Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ionic Liquids and Electrolytes with Flexible Aromatic Anions2023Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 29, nr 41, artikel-id e202301000Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Five new n-tetrabutylphosphonium (P4444)+ cation based ionic liquids (ILs) with oligoether substituted aromatic carboxylate anions have been synthesized. The nature and position of the oligoether chain affect thermal stability (up to 330 ºC), phase behaviour (Tg < -55 ºC) and ion transport. Furthermore, with the aim of application in lithium batteries, electrolytes were created for two of the ILs by 10 mol% doping using the corresponding Li-salts. This affects the ion diffusion negatively, from being higher and equal for cations and anions to lower for all ions and unequal. This is due to the stronger ionic interactions and formation of aggregates, primarily between the Li+ ions and the carboxylate group of the anions. Electrochemically, the electrolytes have electrochemical stability windows up to 3.5 V, giving some promise for battery application.

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  • 12.
    Ahmed, Mukhtiar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Filippov, Andrei
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Johansson, Patrik
    Materials Physics, Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Pyrrolidium- and Imidazolium-Based Ionic Liquids and Electrolytes with Flexible Oligoether Anions2024Ingår i: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 25, nr 9, artikel-id e202300810Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new class of fluorine-free ionic liquids (ILs) and electrolytes based on aliphatic flexible oligoether anions, 2-(2-methoxyethoxy)acetate (MEA) and 2-[2-(2-methoxyethoxy)ethoxy]acetate (MEEA), coupled with pyrrolidinium and imidazolium cations is introduced. For the ILs with MEEA anions, Li+ conducting electrolytes are created by doping the ILs with 30 mol % of LiMEEA. The structural flexibility of the oligoether functionality in the anion results in glass transition temperatures (Tg) as low as −60 °C for the neat ILs and the electrolytes. The imidazolium-based ILs and electrolytes reveal better thermal stabilities but higher Tg and lower electrochemical stabilities than the corresponding pyrrolidinium-based analogues. All neat ILs show comparable transport properties for the cations and these decrease by the addition of lithium salt – the pyrrolidinium-based electrolyte being affected the most.

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  • 13.
    Ahmed, Mukhtiar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rao, Soniya S.
    Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Filippov, Andrei
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Johansson, Patrik
    Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Aromatic Heterocyclic Anion Based Ionic Liquids and Electrolytes2023Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 25, nr 4, s. 3502-3512Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Five new ionic materials comprising fluorine-free aromatic heterocyclic anions based on pyridine and pyrazine combined with a common n-tetrabutylphosphonium cation, (P4444)+, result in two room temperature ionic liquids (RTILs), one semi-solid, and two organic ionic plastic crystals (OIPCs) with melting points >20 °C. The OIPCs showed a plastic crystalline phase, multiple solid–solid transitions, and plastic crystalline and melt phases. For both the neat RTILs and the Li+ conducting electrolytes, the nature and strength of the ion–ion interactions mainly depend on the position of the nitrogen atom with respect to the carboxylate group in the anions. Furthermore, for the RTILs the ionic conductivity is effected by the electronic structure and flexibility of the ions and the anions diffuse faster than the (P4444)+ cation, but are slowed down in the electrolytes due to the strong electrostatic interactions between the carboxylate group of the anions and the Li+, as shown both experimentally and computationally. Overall, this study describes the effect of structural tuning of aromatic anions on the ion–ion interactions and introduces new ionic materials with promising properties to be used as solid and liquid electrolytes in energy storage devices.

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  • 14.
    Ahmed, Naeem
    et al.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, Bangi, 43600, Selangor, Malaysia; Molecular Electrochemistry Laboratory, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, China.
    Masood, Asad
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, Bangi, 43600, Selangor, Malaysia.
    Mumtaz, Rubab
    Department of Physics, Quaid-e-Azam University, Islamabad, Pakistan.
    Wee, M. F. Mohd Razip
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, Bangi, 43600, Selangor, Malaysia.
    Chan, Kok Meng
    Petroliam Nasional Berhad, PETRONAS Twin Towers, KLCC, Kuala Lumpur, 50088, Malaysia.
    Patra, Anuttam
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Siow, Kim S.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, Bangi, 43600, Selangor, Malaysia.
    Quad-atmospheric Pressure Plasma Jet (q-APPJ) Treatment of Chilli Seeds to Stimulate Germination2024Ingår i: Plasma chemistry and plasma processing, ISSN 0272-4324, E-ISSN 1572-8986, Vol. 44, nr 1, s. 509-522Artikel i tidskrift (Refereegranskat)
  • 15.
    Ahmed, Naeem
    et al.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia.
    Masood, Asad
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia.
    Siow, Kim S.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia.
    Wee, M. F. Mohd Razip
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia.
    Haron, Farah Farhanah
    Pest and Disease Management Programme, Horticulture Research Centre, Malaysian Agricultural Research and Development Institute, 43400, Serdang, Selangor, Malaysia.
    Patra, Anuttam
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Nayan, Nafarizal
    Biosensor and Bioengineering Lab, Microelectronics and Nanotechnology-Shamsuddin Research Center, Institute for Integrated Engineering, Universiti Tun Hussein Onn Malaysia, 86400, Parit Raja, Batu Pahat, Johor, Malaysia.
    Soon, Chin Fhong
    Biosensor and Bioengineering Lab, Microelectronics and Nanotechnology-Shamsuddin Research Center, Institute for Integrated Engineering, Universiti Tun Hussein Onn Malaysia, 86400, Parit Raja, Batu Pahat, Johor, Malaysia.
    Effects of Oxygen (O2) Plasma Treatment in Promoting the Germination and Growth of Chili2022Ingår i: Plasma chemistry and plasma processing, ISSN 0272-4324, E-ISSN 1572-8986, Vol. 42, nr 1, s. 91-108Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In general, seed germination is improved by low-pressure plasma treatment using precursors such as air, nitrogen, O2, and argon, etc. For the first time, low-pressure O2 plasma was used to treat chili seeds in this study. When compared to untreated and vacuum-treated seeds, O2 plasma treatment using the discharge power of 80 W for 60 s significantly improves chili seed germination and growth. The effect of vacuum on the germination and growth of chili seeds was also studied and shown to be negligible. The physical and chemical changes induced by O2 plasma treatment were investigated to understand the plasma treatment to germination improvement. Combinatory etching and chemical modification aided imbibition and increased germination percentage in this O2 plasma treatment on chili seeds. The success of this method has the potential to be scaled up to solve food security issues with seeds that would otherwise struggle to germinate.

  • 16.
    Ahmed, Naeem
    et al.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor, Malaysia.
    Shahid, Muhammad
    Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor, Malaysia.
    Siow, Kim S
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor, Malaysia.
    Razip Wee, M F Mohd
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor, Malaysia.
    Haron, Farah Farhanah
    Pest and Disease Management Programme, Horticulture Research Centre, Malaysian Agricultural Research and Development Institute, Serdang 43400, Selangor, Malaysia.
    Patra, Anuttam
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Fazry, Shazrul
    Department of Food Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor, Malaysia.
    Germination and growth improvement of papaya utilizing oxygen (O2) plasma treatment2022Ingår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 55, nr 25, artikel-id 255205Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In general, cold plasma treatment improves crop germination and growth. The purpose of this research is to examine the impact of low-pressure O2 plasma treatment on the germination and growth kinetics of papaya seeds. Seeds were treated for 40 s at a discharge power of 80 W using O2 as a monomer. Physical and chemical changes were studied to understand the mechanism of germination and growth improvement. Furthermore, changes in phytohormones and antioxidant activity that were beneficial to germination were also examined. O2 plasma treatment improved wettability, surface etching, and oxidation, and affected other molecular-level changes leading to a 16% germination improvement in papaya.

  • 17.
    Ahmed, Naeem
    et al.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia.
    Siow, Kim S.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia.
    Wee, M. F. Mohd Razip
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia.
    Patra, Anuttam
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    A study to examine the ageing behaviour of cold plasma-treated agricultural seeds2023Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 13, artikel-id 1675Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cold plasma (low pressure) technology has been effectively used to boost the germination and growth of various crops in recent decades. The durability of these plasma-treated seeds is essential because of the need to store and distribute the seeds at different locations. However, these ageing effects are often not ascertained and reported because germination and related tests are carried out within a short time after the plasma-treatment. This research aims to fill that knowledge gap by subjecting three different types of seeds (and precursors): Bambara groundnuts (water), chilli (oxygen), and papaya (oxygen) to cold plasma-treatment. Common mechanisms found for these diverse seed types and treatment conditions were the physical and chemical changes induced by the physical etching and the cold plasma on the seeds and subsequent oxidation, which promoted germination and growth. The high glass transition temperature of the lignin-cellulose prevented any physical restructuring of the surfaces while maintaining the chemical changes to continue to promote the seeds germination and growth. These changes were monitored over 60 days of ageing using water contact angle (WCA), water uptake, electrical conductivity, field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS). The vacuum effect was also investigated to separate its effect from cold plasma (low pressure). This finding offers a framework for determining how long agricultural seeds that have received plasma treatment can be used. Additionally, there is a need to transfer this research from the lab to the field. Once the impact of plasma treatment on seeds has been estimated, it will be simple to do so.

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  • 18.
    Ahmed, Naeem
    et al.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia.
    Siow, Kim S.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia.
    Wee, Mohd Farhanulhakim Mohd Razip
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia.
    Ho, Wai Kuan
    Crops for Future, Jln Broga, Semenyih 43500, Selangor, Malaysia.
    Patra, Anuttam
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    The Hydrophilization and Subsequent Hydrophobic Recovery Mechanism of Cold Plasma (CP) Treated Bambara Groundnuts2022Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 1055, s. 161-169Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plasma hydrophilization and subsequent hydrophobic recovery in Bambara groundnuts are studied for the first time. Bambara groundnut seeds were treated with cold plasma (CP) for 10 seconds at 10 watts using water as a monomer. The contact angle, as well as physical and chemical changes, were used to determine the kinetics of hydrophobic recovery. The hydrophilic state of Bambara groundnut seeds had decreased after 60 days, but not to original hydrophobicity, and also the recovery rate is slower than those observed on synthetic polymer. However, this slower hydrophobic recovery makes CP treatment as an effective method for long-term seed storage.

  • 19.
    Akhtar, Farid
    et al.
    Department of Materials and Environmental Chemistry, Stockholm University.
    Ojuva, Arto
    Stockholm University, Department of Materials and Environmental Chemistry.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Bergström, Lennart M.
    Department of Materials and Environmental Chemistry, Stockholm University.
    All-Zeolite Membranes2010Konferensbidrag (Refereegranskat)
  • 20.
    Akhtar, Farid
    et al.
    Department of Materials and Environmental Chemistry, Stockholm University.
    Ojuva, Arto
    Stockholm University, Department of Materials and Environmental Chemistry.
    Wirawan, Kompiang
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Bergström, Lennart
    Department of Materials and Environmental Chemistry, Stockholm University.
    PCP procesing of Zeolite supports for all-zeolite membranes2011Konferensbidrag (Refereegranskat)
  • 21.
    Akhtar, Farid
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Department of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden.
    Sjöberg, Erik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Korelskiy, Danil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rayson, Mark
    Department of Chemistry, The University of Surrey, Guildford, Surrey GU2 7XH, UK.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Bergström, Lennart
    Department of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden.
    Preparation of graded silicalite-1 substrates for all-zeolite membranes with excellent CO2/H2 separation performance2015Ingår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 493, s. 206-211Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    raded silicalite-1 substrates with a high gas permeability and low surface roughness have been produced by pulsed current processing of a thin coating of a submicron silicalite-1 powder onto a powder body of coarser silicalite-1 crystals. Thin zeolite films have been hydrothermally grown onto the graded silicalite-1 support and the all-zeolite membranes display an excellent CO2/H2 separation factor of 12 at 0 °C and a CO2 permeance of 21.3×10-7 mol m-2 s-1 Pa-1 for an equimolar CO2/H2 feed at 505 kPa and 101 kPa helium sweep gas. Thermal cracking estimates based on calculated surface energies and measured thermal expansion coefficients suggest that all-zeolite membranes with a minimal thermal expansion mismatch between the graded substrate and the zeolite film should remain crack-free during thermal cycling and the critical calcination step.

  • 22.
    Alinejad, M.
    et al.
    Department of Forestry, Michigan State University, East Lansing, United States.
    Henry, C.
    Department of Forestry, Michigan State University, East Lansing, United States.
    Nikafshar, S.
    Department of Forestry, Michigan State University, East Lansing, United States.
    Gondaliya, A.
    Chemical Engineering and Materials Science, Michigan State University, East Lansing, United States.
    Bagheri, B.
    Chemical Engineering and Materials Science, Michigan State University, East Lansing, United States.
    Chen, N.
    Eastern Regional Research Center, USDA-ARS, Wyndmoor, United States.
    Singh, S.K.
    Chemical and Biological Engineering, Montana State University, Bozeman, United States.
    Hodge, David
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Nejad, M.
    Department of Forestry, Michigan State University, East Lansing, United States. Chemical Engineering and Materials Science, Michigan State University, East Lansing, United States..
    Lignin-based polyurethanes: Opportunities for bio-based foams, elastomers, coatings and adhesives2019Ingår i: Polymers, E-ISSN 2073-4360, Vol. 11, nr 7, artikel-id 1202Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polyurethane chemistry can yield diverse sets of polymeric materials exhibiting a widerange of properties for various applications and market segments. Utilizing lignin as a polyol presentsan opportunity to incorporate a currently underutilized renewable aromatic polymer into theseproducts. In this work, we will review the current state of technology for utilizing lignin as a polyolreplacement in different polyurethane products. This will include a discussion of lignin structure,diversity, and modification during chemical pulping and cellulosic biofuels processes, approachesfor lignin extraction, recovery, fractionation, and modification/functionalization. We will discussthe potential of incorporation of lignins into polyurethane products that include rigid and flexiblefoams, adhesives, coatings, and elastomers. Finally, we will discuss challenges in incorporating ligninin polyurethane formulations, potential solutions and approaches that have been taken to resolvethose issues.

  • 23.
    Amjad, Um-e-Salma
    et al.
    Department of Chemical Engineering, COMSATS University Islamabad, Lahore Campus, Defence Road, Off Raiwind Road, Lahore 54000, Pakistan.
    Tajjamal, Arshia
    Department of Chemical Engineering, COMSATS University Islamabad, Lahore Campus, Defence Road, Off Raiwind Road, Lahore 54000, Pakistan.
    Ul-Hamid, Anwar
    Core Research Facilities, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
    Faisal, Abrar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Department of Chemical Engineering, COMSATS University Islamabad, Lahore Campus, Defence Road, Off Raiwind Road, Lahore 54000, Pakistan.
    Zaidi, Syed Ammar Hussain
    Department of Chemical Engineering, COMSATS University Islamabad, Lahore Campus, Defence Road, Off Raiwind Road, Lahore 54000, Pakistan.
    Sherin, Lubna
    Department of Chemistry, COMSATS University Islamabad, Lahore Campus, Defence Road, Off Raiwind Road, Lahore 54000, Pakistan.
    Mir, Amna
    Department of Physics, COMSATS University Islamabad, Lahore Campus, Defence Road, Off Raiwind Road, Lahore 54000, Pakistan.
    Mustafa, Maria
    Department of Chemical Engineering, COMSATS University Islamabad, Lahore Campus, Defence Road, Off Raiwind Road, Lahore 54000, Pakistan.
    Ahmad, Nabeel
    Department of Chemical Engineering, COMSATS University Islamabad, Lahore Campus, Defence Road, Off Raiwind Road, Lahore 54000, Pakistan.
    Hussain, Murid
    Department of Chemical Engineering, COMSATS University Islamabad, Lahore Campus, Defence Road, Off Raiwind Road, Lahore 54000, Pakistan.
    Park, Young-Kwon
    School of Environmental Engineering, University of Seoul, Seoul 02504, Republic of Korea.
    Catalytic cracking of polystyrene pyrolysis oil: Effect of Nb2O5 and NiO/Nb2O5 catalyst on the liquid product composition2022Ingår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 141, s. 240-250Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The catalytic cracking of polystyrene pyrolysis oil was investigated over a Nb2O5 and a NiO/Nb2O5 catalyst in a fixed bed reactor. First, the pyrolysis of two different polystyrene feedstock (polystyrene foam and polystyrene pellet) was carried out in a semi-batch reactor, and the resulting polystyrene pellets pyrolysis oil was selected for catalytic cracking reaction because of its high liquid yield (85%). Catalytic cracking experiments were then performed at different temperatures (350–500 °C) using Nb2O5 or NiO/Nb2O5 catalyst. Gas chromatography–mass spectrometry analysis of liquid product obtained from the catalytic cracking process showed that the dimers in the pyrolysis oil were converted to monomers during the catalytic cracking process. The catalytic cracking results also showed that the NiO/Nb2O5 catalyst (having slightly higher acidic sites) had slightly higher activity for monomer conversion than the Nb2O5 catalyst (having less acidic sites). X-ray diffraction, transmission electron microscopy, pyridine Fourier transform infrared spectroscopy, NH3 Temperature Programmed Desorption and X-ray photoelectron spectroscopy were used to characterize the catalyst. The highest catalytic cracking activity was observed at 400 °C with the Nb2O5 catalyst with 4% toluene, 6% ethylbenzene, approximately 50% styrene, 13% α-methyl styrene, and only 6% of dimers in the liquid oil. The increase in temperature positively affected the yield of gases during catalytic cracking process.

  • 24.
    Amulya, K.
    et al.
    National University of Ireland, Galway, Ireland.
    Dahiya, Shikha
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Venkata Mohan, S.
    Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering (DEE), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, Telangana, India.
    Building circular bio-based economy through sustainable waste management2023Ingår i: Bioremediation and Bioeconomy: a Circular Economy Approach / [ed] Majeti Narasimha Vara Prasad, Elsevier, 2023, 2, s. 639-666Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 25.
    An, Rong
    et al.
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
    Laaksonen, Aatto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden; Center of Advanced Research in Bionanoconjugates and Biopolymers, “Petru Poni” Institute of Macromolecular Chemistry, Iasi 700469, Romania; State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Wu, Muqiu
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
    Zhu, Yudan
    State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Lu, Xiaohua
    State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Ji, Xiaoyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Atomic force microscopy probing interactions and microstructures of ionic liquids at solid surfaces2022Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, nr 14, s. 11098-11128Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Ionic liquids (ILs) are room temperature molten salts that possess preeminent physicochemical properties and have shown great potential in many applications. However, the use of ILs in surface-dependent processes, e.g. energy storage, is hindered by the lack of a systematic understanding of the IL interfacial microstructure. ILs on the solid surface display rich ordering, arising from coulombic, van der Waals, solvophobic interactions, etc., all giving near-surface ILs distinct microstructures. Therefore, it is highly important to clarify the interactions of ILs with solid surfaces at the nanoscale to understand the microstructure and mechanism, providing quantitative structure–property relationships. Atomic force microscopy (AFM) opens a surface-sensitive way to probe the interaction force of ILs with solid surfaces in the layers from sub-nanometers to micrometers. Herein, this review showcases the recent progress of AFM in probing interactions and microstructures of ILs at solid interfaces, and the influence of IL characteristics, surface properties and external stimuli is thereafter discussed. Finally, a summary and perspectives are established, in which, the necessities of the quantification of IL–solid interactions at the molecular level, the development of in situ techniques closely coupled with AFM for probing IL–solid interfaces, and the combination of experiments and simulations are argued.

  • 26.
    An, Rong
    et al.
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China. Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
    Qiu, Xiuhua
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Riehemann, Kristina
    Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
    Fuchs, Harald
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China. Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
    Controlling the nanoscale friction by layered ionic liquid films2020Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 22, nr 26, s. 4941-14952Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nanofriction coefficient of ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), on the surfaces of mica and graphite was investigated using atomic force microscopy (AFM). A pronounced layered spatial distribution was found in the IL film formed on the solid substrates and can be divided into 3 well distinguishable regions exhibiting different physical properties with increasing distance from the substrate. We found that the friction coefficient (μ) increases monotonically as the layering thickness decreases, no matter what the thickness of the bulk IL is. This suggests that the layering assembled IL at solid surfaces is more important than the bulk phase in determining the magnitude of the nanoscale friction. The increase in the friction coefficient as the layering thickness decreases is most likely attributed to the assembled ordered IL layers closer to the substrate surfaces having a greater activation barrier for unlocking the surfaces to allow shear.

  • 27.
    An, Rong
    et al.
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Wei, Yudi
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Qiu, Xiuhua
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Dai, Zhongyang
    High Performance Computing Department, National Supercomputing Center in Shenzhen, Shenzhen, 518055, China.
    Wu, Muqiu
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Gnecco, Enrico
    Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Jena, 07743, Germany.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zhang, Wenling
    School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Ionic liquids on uncharged and charged surfaces: In situ microstructures and nanofriction2022Ingår i: Friction, ISSN 2223-7690, E-ISSN 2223-7704, Vol. 10, nr 11, s. 1893-1912Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In situ changes in the nanofriction and microstructures of ionic liquids (ILs) on uncharged and charged surfaces have been investigated using colloid probe atomic force microscopy (AFM) and molecular dynamic (MD) simulations. Two representative ILs, [BMIM][BF4] (BB) and [BMIM][PF6] (BP), containing a common cation, were selected for this study. The torsional resonance frequency was captured simultaneously when the nanoscale friction force was measured at a specified normal load; and it was regarded as a measure of the contact stiffness, reflecting in situ changes in the IL microstructures. A higher nanoscale friction force was observed on uncharged mica and highly oriented pyrolytic graphite (HOPG) surfaces when the normal load increased; additionally, a higher torsional resonance frequency was detected, revealing a higher contact stiffness and a more ordered IL layer. The nanofriction of ILs increased at charged HOPG surfaces as the bias voltage varied from 0 to 8 V or from 0 to —8 V. The simultaneously recorded torsional resonance frequency in the ILs increased with the positive or negative bias voltage, implying a stiffer IL layer and possibly more ordered ILs under these conditions. MD simulation reveals that the [BMIM]+ imidazolium ring lies parallel to the uncharged surfaces preferentially, resulting in a compact and ordered IL layer. This parallel “sleeping” structure is more pronounced with the surface charging of either sign, indicating more ordered ILs, thereby substantiating the AFM-detected stiffer IL layering on the charged surfaces. Our in situ observations of the changes in nanofriction and microstructures near the uncharged and charged surfaces may facilitate the development of IL-based applications, such as lubrication and electrochemical energy storage devices, including supercapacitors and batteries.

  • 28.
    An, Rong
    et al.
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, P.R. China. Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms, Universität Münster, Münster, Germany .
    Wu, Muqiu
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, P.R. China.
    Li, Jing
    State Key Laboratory of Materials Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, P.R. China.
    Qiu, Xiuhua
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, P.R. China.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Li, Jianliang
    Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, P.R. China.
    On the Ionic Liquid Film ‘Pinned’ by Core-Shell Structured Fe3O4@Carbon Nanoparticles and Their Tribological Properties2019Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, nr 48, s. 26387-26398Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A strongly ‘pinned’ ionic liquid (IL, [BMIM][PF6]) film onto silicon (Si) surface via carbon capsuled Fe3O4 core-shell (Fe3O4@C) nanoparticles is achieved, revealing excellent friction-reducing ability at a high load. The adhesion force is measured as ~ 198 nN at the Fe3O4@C-Si interface by Fe3O4@C colloidal AFM tip, which is stronger than that at both Fe3O4@C-Fe3O4@C (~ 60 nN) and IL-Si (~ 10 nN) interfaces, indicating a strong ‘normal pin-force’ towards the Si substrate. The resulting strengthened force enables the formation of lateral IL networks via the dipole-dipole attractions among Fe3O4 cores. The observed blue shift of the characteristic band related to the IL anion in ATR-FTIR spectra confirmed the enhanced interaction. The N-Si, P-O chemical bonds formed as a result of the IL interactions with the Si substrate confirmed by XPS spectroscopy suggested that the IL lay on the Si plane. This orientation is favorable for Fe3O4@C nanoparticles to exert ‘normal pin-force’ and press the IL film strongly onto surfaces. The IL ios/clusters are thus anchored by these Fe3O4@C ‘pins’ onto the substrate to form a dense film, resulting in a smaller interaction size parameter, which is responsible for the reduced friction coefficient μ.

  • 29.
    An, Rong
    et al.
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
    Wu, Nanhua
    Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China.
    Gao, Qingwei
    College of Environmental and Chemical Engineering, Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, China.
    Dong, Yihui
    Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 76100, Israel.
    Laaksonen, Aatto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden; Center of Advanced Research in Bionanoconjugates and Biopolymers, ‘‘Petru Poni” Institute of Macromolecular Chemistry, Iasi 700469, Romania; State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ji, Xiaoyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Fuchs, Harald
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China; Center for Nanotechnology (CeNTech), Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
    Integrative studies of ionic liquid interface layers: bridging experiments, theoretical models and simulations2024Ingår i: Nanoscale Horizons, ISSN 2055-6756, Vol. 9, nr 4, s. 506-535Artikel, forskningsöversikt (Refereegranskat)
  • 30.
    An, Rong
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing.
    Zhou, Guobing
    School of Chemical Biological and Materials Engineering, University of Oklahoma.
    Zhu, Yudan
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University.
    Zhu, Wei
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University.
    Huang, Liangliang
    School of Chemical Biological and Materials Engineering, University of Oklahoma.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Friction of Ionic Liquid–Glycol Ether Mixtures at Titanium Interfaces: Negative Load Dependence2018Ingår i: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 5, nr 14, artikel-id 1800263Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The atomic force microscopy experiments and nonequilibrium molecular dynamics (NEMD) simulations demonstrate a negative friction–load dependence to ionic liquid–glycol ether mixtures, that is, the friction decreases as the normal load increases. NEMD simulations reveal a structural reorientation of the studied ionic liquid (IL): as the normal load increases, the cation alkyl chains of ILs change the orientation to preferentially parallel to the tip scanning path. The flat‐oriented IL structures, similar to the “blooming lotus leaf,” produce a new sliding interface and reduce the friction. A further molecular dynamics simulation is carried out by adopting slit‐pore models to mimic the tip approaching process to confirm the dynamics of ILs. A faster diffusion of ILs in the smaller slit pore is observed. The faster diffusion of ILs in the more confined slit pore facilitates the structural reorientation of ILs. The resulted new sliding surface is responsible for the observed smaller friction at higher loads, also known as the negative friction–load dependence. These findings provide a fundamental explanation to the role of ILs in interfacial lubrications. They help to understand liquid flow properties under confinement, with implications for the development of better nanofluidic devices.

  • 31.
    An, Rong
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing.
    Zhou, Guobing
    School of Chemical Biological and Materials Engineering, University of Oklahoma.
    Zhu, Yudan
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University.
    Zhu, Wei
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University.
    Huang, Liangliang
    School of Chemical Biological and Materials Engineering, University of Oklahoma.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Friction of Ionic Liquid–Glycol Ether Mixtures at Titanium Interfaces: Negative Load Dependence2018Ingår i: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 5, nr 14, artikel-id 1800266Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Structural reorientation of alkyl chains in the phosphonium cation of orthoborate ionic liquid mixed with glycol ether occurs with increasing normal load of the AFM tip. The flat reoriented structure, similar to the ‘blooming lotus leaf’, produces a new sliding interface that is responsible for the observed lower friction at higher loads. This work is reported by Rong An, Liangliang Huang, Faiz Ullah Shah and co‐workers in article number 1800263.

  • 32.
    Anasontzis, George E
    et al.
    Industrial Biotechnology, Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden; Wallenberg Wood Science Center, Chalmers University of Technology, Gothenburg, Sweden.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Challenges in ethanol production with Fusarium oxysporum through consolidated bioprocessing2014Ingår i: Bioengineered, ISSN 2165-5979, E-ISSN 2165-5987, Vol. 5, nr 6, s. 393-395Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Fusarium oxysporum has been reported as being able to both produce the enzymes necessary to degrade lignocellulosic biomass to sugars and also ferment the monosaccharides to ethanol under anaerobic or microaerobic conditions. However, in order to become an economically feasible alternative to other ethanol-producing microorganisms, a better understanding of its physiology, metabolic pathways, and bottlenecks is required, together with an improvement in its efficiency and robustness. In this report, we describe the challenges for the future and give additional justification for our recent publication.

  • 33.
    Anasontzis, George E.
    et al.
    National and Kapodistrian University of Athens, Chalmers University of Technology, Department of Chemical and Biological Engineering, Microbial Biotechnology Unit, Sector of Botany, Department of Biology, National and Kapodistrian University of Athens, Zografou.
    Kourtoglou, Elisavet
    National Technical University of Athens, BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Villas-Boâs, Silas G
    Centre for Microbial Innovation, School of Biological Sciences, The University of Auckland, Technical University of Denmark.
    Hatzinikolaou, Dimitris G.
    Department of Chemical Engineering, National Technical University of Athens.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Metabolic Engineering of Fusarium oxysporum to Improve Its Ethanol-Producing Capability2016Ingår i: Frontiers in Microbiology, E-ISSN 1664-302X, Vol. 7, artikel-id 632Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fusarium oxysporum is one of the few filamentous fungi capable of fermenting ethanol directly from plant cell wall biomass. It has the enzymatic toolbox necessary to break down biomass to its monosaccharides and, under anaerobic and microaerobic conditions, ferments them to ethanol. Although these traits could enable its use in consolidated processes and thus bypass some of the bottlenecks encountered in ethanol production from lignocellulosic material when Saccharomyces cerevisiae is used-namely its inability to degrade lignocellulose and to consume pentoses-two major disadvantages of F. oxysporum compared to the yeast-its low growth rate and low ethanol productivity-hinder the further development of this process. We had previously identified phosphoglucomutase and transaldolase, two major enzymes of glucose catabolism and the pentose phosphate pathway, as possible bottlenecks in the metabolism of the fungus and we had reported the effect of their constitutive production on the growth characteristics of the fungus. In this study, we investigated the effect of their constitutive production on ethanol productivity under anaerobic conditions. We report an increase in ethanol yield and a concomitant decrease in acetic acid production. Metabolomics analysis revealed that the genetic modifications applied did not simply accelerate the metabolic rate of the microorganism; they also affected the relative concentrations of the various metabolites suggesting an increased channeling toward the chorismate pathway, an activation of the γ-aminobutyric acid shunt, and an excess in NADPH regeneration

  • 34.
    Anasontzis, George
    et al.
    Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Kourtoglou, Elisavet
    BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Mamma, Diomi
    BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Villas-Boâs, Silas G
    Centre for Microbial Innovation, School of Biological Sciences, The University of Auckland.
    Hatzinikolaou, Dimitris
    Microbial Biotechnology Unit, Sector of Botany, Department of Biology, National and Kapodistrian University of Athens.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Constitutive homologous expression of phosphoglucomutase and transaldolase increases the metabolic flux of Fusarium oxysporum2014Ingår i: Microbial Cell Factories, ISSN 1475-2859, E-ISSN 1475-2859, Vol. 13, artikel-id 43Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: Fusarium oxysporum is among the few filamentous fungi that have been reported of being able to directly ferment biomass to ethanol in a consolidated bioprocess. Understanding its metabolic pathways and their limitations can provide some insights on the genetic modifications required to enhance its growth and subsequent fermentation capability. In this study, we investigated the hypothesis reported previously that phosphoglucomutase and transaldolase are metabolic bottlenecks in the glycolysis and pentose phosphate pathway of the F. oxysporum metabolism.RESULTS: Both enzymes were homologously overexpressed in F. oxysporum F3 using the gpdA promoter of Aspergillus nidulans for constitutive expression. Transformants were screened for their phosphoglucomutase and transaldolase genes expression levels with northern blot. The selected transformant exhibited high mRNA levels for both genes, as well as higher specific activities of the corresponding enzymes, compared to the wild type. It also displayed more than 20 and 15% higher specific growth rate upon aerobic growth on glucose and xylose, respectively, as carbon sources and 30% higher xylose to biomass yield. The determination of the relative intracellular amino and non-amino organic acid concentrations at the end of growth revealed higher abundance of most determined metabolites between 1.5- and 3-times in the recombinant strain compared to the wild type. Lower abundance of the determined metabolites of the Krebs cycle and an 68-fold more glutamate were observed at the end of the cultivation, when xylose was used as carbon source.CONCLUSIONS: Homologous overexpression of phosphoglucomutase and transaldolase in F. oxysporum was shown to enhance the growth characteristics of the strain in both xylose and glucose in aerobic conditions. The intracellular metabolites profile indicated how the changes in the metabolome could have resulted in the observed growth characteristics.

  • 35.
    Andersson, Anna
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    CFD optimization of photochemical UV reactors for VOC degradation2017Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In 2016 the World Health Organization released a report on Ambient Air Pollution, in this it was stated that one out of every nine deaths all around the world in 2012 were due to air-pollution-related conditions. Urban air pollution involves a broad range of compounds from many diverse sources. Volatile Organic Compounds (VOCs) are some of the important compounds. Almost all VOCs are known to have effect on human health, many of them are carcinogenic. VOCs also contribute to the ground level photochemical smog and the reduction of the stratospheric ozone layer. Therefore, it is important to control the emissions of VOCs from industries and restaurants.

    Today most big scale VOC removal is done by thermal or catalytic incineration. While smaller scale air purification is done by using adsorbing materials such as activated carbon. Both these methods have their drawbacks. A promising technology, which is also environmentally friendly, is UV reactors.

    This thesis is a collaboration with the company Centriair, a company developing and selling UV reactors mainly for odor removal. The UV reactors which are in use today show acceptable performance, with a conversion of 50-60%. However, they have yet to be optimized to get the most out of the reactors. The aim was to try to reach an as high conversion of VOCs as possible in a prototype scale compared to a reference reactor, also in prototype scale. The reactors were simulated using the Computational Fluid Dynamic (CFD) software COMSOL Multiphysics® 5.2a. The simulation was based on earlier lab scale experiments with UV reactors.

    The conclusion from doing this thesis is that the most important challenge with a UV reactor up-scaling and optimization is the dark zones and the bypassing effect given by these. It is very important that the irradiation reaches the whole reactor and that all gas is affected by it. It is also important that the gas is given time to stay by the light sources as long as possible. Two reactors in this thesis had very high conversion results and thus showed potential of being very effective UV reactors. These two reactors showed conversion results of 45% respective 61% higher than the reference reactor used by Centriair today.

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  • 36.
    Andersson, Christian
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Biobased production of succinic acid by Escherichia coli fermentation2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The prospects of peak oil, climate change and the dependency of fossil carbon have urged research and development of production methods for the manufacture of fuels and chemicals from renewable resources (biomass). The present thesis illustrates different aspects of biobased succinic acid production by a metabolically engineered E. coli strain. The main areas of the thesis are sugar utilisation and feedstock flexibility, and fermentation inhibition, both due to toxic compound derived from the raw material and the fermentation products themselves.The first part of this thesis aimed to investigate the fermentation characteristics of AFP184 in a medium consisting of corn steep liquor, inorganic salts and different sugar sources without supplementation with high-cost nutrients such as yeast extract and peptone. The effects of different sugars, sucrose, glucose, fructose, xylose, equal mixtures of glucose-fructose and glucose-xylose, on succinic acid production kinetics and yields in an industrially relevant medium were investigated. AFP184 was able to utilise all sugars and sugar combinations except sucrose for biomass generation and succinate production. Using glucose resulted in the highest yield, 0.83 (g succinic acid per g sugar consumed anaerobically). Using a high initial sugar concentration resulted in volumetric productivities of almost 3 g L-1 h-1, which is above estimated values for economically feasible production. However, succinic acid production ceased at final concentrations greater than 40 g L-1. To further increase succinic acid concentrations, fermentations using NH4OH, NaOH, KOH, K2CO3, and Na2CO3 as neutralising agents were performed and compared. It was shown that substantial improvements could be made by using alkali bases to neutralise the fermentations. The highest concentrations and productivities were achieved when Na2CO3 was used, 77 g L-1 and 3 g L-1 h-1 respectively. A gradual decrease in succinate productivity was observed during the fermentations, which was shown to be due to succinate accumulation in the broth and not as a result of the addition of neutralising agent or the subsequent increase in osmolarity.To maintain high succinate productivity by keeping a low extracellular succinic acid concentration fermentations were interrupted and cells recovered and resuspended in fresh media. By removing the succinate it was possible to maintain high succinic acid productivity for a prolonged time. Cells subjected to high concentrations of succinate were also able to regain high productivity once transferred into a succinate-free medium.In the last part of the thesis succinic acid production from softwood dilute acid hydrolysates was demonstrated. This study involved establishing the degree of detoxification necessary for growth and fermentation using industrial hydrolysates. Detoxification by treatment with lime and/or activated carbon was investigated and the results show that it was possible to produce succinate from softwood hydrolysates in yields comparable to those for synthetic sugars.The work done in this thesis increases the understanding of succinic acid production with AFP184, illustrate its limitations, and suggests improvements in the current technology with the long term aim of increasing the economical feasibility of biochemical succinic acid production.

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  • 37.
    Andersson, Christian
    et al.
    Luleå tekniska universitet.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Berglund, Kris
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Process for producing succinic acid from sucrose2005Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    A process for hydrolyzing sucrose to glucose and fructose using succinic acid is described. The hydrolysate can be used to produce purified glucose and/or fructose or can be used as a carbon source for fermentations to produce various chemicals including succinic acid.

  • 38. Anthonis, Marc Henry
    et al.
    Bons, Anton-Jan
    Deckman, H. W.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Lai, Wenyih F.
    Peters, J.A.J.
    Crystalline molecular sieve layers and processes for their manufacture2000Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    A process is described for the manufacture of crystalline molecular sieve layers with good para-xylene over meta-xylene selectivity's good para-xylene permeances and selectivities. The process requires impregnation of the support prior to hydrothermal synthesis using the seeded method and may be undertaken with pre-impregnation masking. The crystalline molecular sieve layer has a selectivity (.alpha..sub.x) for para-xylene over meta-xylene of 2 or greater and a permeance (Q.sub.x) for para-xylene of 3.27.times.10.sup.-8 mole(px)/m.sup.2.s.Pa(px) or greater measured at a temperature of .gtoreq.250.degree. C. and an aromatic hydrocarbon partial pressure of .gtoreq.10.times.10.sup.3 Pa.

  • 39.
    Antonopoulou, Io
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Development of biocatalytic processes for selective antioxidant production2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Feruloyl esterases (FAEs, EC 3.1.1.73) represent a subclass of carboxylic acid esterases that under normal conditions catalyze the hydrolysis of the ester bond between hydroxycinnamic acids (ferulic acid, sinapic acid, caffeic acid, p-coumaric acid) and sugar residues in plant cell walls. Based on their specificity towards monoferulates and diferulates, substitutions on the phenolic ring and on their amino acid sequence identity, they have been classified into four types (A-D) while phylogenetic analysis has resulted in classification into thirteen subfamilies (SF1-13). Under low water content, these enzymes are able to catalyze the esterification of hydroxycinnamic acids or the transesterification of their esters (donor) with alcohols or sugars (acceptor) resulting in compounds with modified lipophilicity, having a great potential for use in the tailor-made modification of natural antioxidants for cosmetic, cosmeceutical and pharmaceutical industries. The work described in this thesis focused on the selection,characterization and application of FAEs for the synthesis of bioactive esters with antioxidant activity in non-conventional media. The basis of the current classification systems was investigated in relation with the enzymes’ synthetic and hydrolytic abilities while the developed processes were evaluated for their efficiency and sustainability.

    Paper I was dedicated to the screening and evaluation of the synthetic abilities of 28 fungal FAEs using acceptors of different lipophilicity at fixed conditions in detergentless microemulsions. It was revealed that FAEs classified in phylogenetic subfamilies related to acetyl xylan esterases (SF5 and 6) showed increased transesterification rates and selectivity. In general, FAEs showed preference on more hydrophilic alcohol acceptors and in descending order to glycerol > 1-butanol > prenol. Homology modeling and small molecule docking simulations were employed as tools for the identification of a potential relationship between the predicted surface and active site properties of selected FAEs and the transesterification selectivity.

    Papers II- IV focused on the characterization of eight promising FAEs and the optimization of reaction conditions for the synthesis of two bioactive esters (prenyl ferulate and L-arabinose ferulate) in detergentless microemulsions. The effect of the medium composition, the donor and acceptor concentration, the enzyme load, the pH, the temperature and the agitation on the transesterification yield and selectivity were investigated. It was observed that the acceptor concentration and enzyme load were crucial parameters for selectivity. Fae125 (Type A, SF5) iiexhibited highest prenyl ferulate yield (81.1%) and selectivity (4.685) converting 98.5% of VFA to products after optimization at 60 mM VFA, 1.5 M prenol, 0.04 mg FAE mL-1, 40oC, 24 h, 53.4:43.4:3.2 v/v/v n-hexane: t-butanol: 100 mM MOPS-NaOH pH 8.0. On the other hand, FaeA1 (Type A, SF5) showed highest L-arabinose ferulate yield (52.2 %) and selectivity (1.120) at 80 mM VFA, 55 mM L-arabinose, 0.02 mg FAE mL-1, 50oC, 8 h, 19.8: 74.7: 5.5 v/v/v n-hexane: t-butanol: 100 mM MOPS-NaOH pH 8.0.

    In paper V, the effect of reaction media on the enzyme stability and transesterification yield and selectivity was studied in different solvents for the synthesis of two bioactive esters: prenyl ferulate and L-arabinose ferulate. The best performing enzyme (Fae125) was used in the optimization of reaction conditions in the best solvent (n-hexane) via response surface methodology. Both bioconversions were best described by a two-factor interaction model while optimal conditions were determined as the ones resulting in highest yield and selectivity.Highest prenyl ferulate yield (87.5%) and selectivity (7.616) were observed at 18.56 mM prenol mM-1VFA, 0.04 mg FAE mL-1, 24.5 oC, 24.5 h, 91.8: 8.2 v/v n-hexane: 100 mM sodium acetate pH 4.7. Highest L-arabinose ferulate yield (56.2%) and selectivity (1.284) were observed at 2.96 mM L-arabinose mM-1VFA, 0.02 mg FAE mL-1, 38.9 oC, 12 h, 90.5: 5.0: 4.5 v/v/v n-hexane: dimethyl sulfoxide: 100 mM sodium acetate pH 4.7. The enzyme could be reused for six consecutive reaction cycles maintaining 66.6% of its initial synthetic activity. The developed bioconversions showed exceptional biocatalyst productivities (> 300 g product g-1FAE) and the waste production was within the range of pharmaceutical processes.

    Paper VI focused on the investigation of the basis of the type A classification of a well-studied FAE from Aspergillus niger(AnFaeA) by comparing its activity towards methyl and arabinose hydroxycinnamic acid esters. For this purpose, L-arabinose ferulateand caffeate were synthesized enzymatically. kcat/Kmratios revealed that AnFaeA hydrolyzed arabinose ferulate 1600 times and arabinose caffeate 6.5 times more efficiently than methyl esters. This study demonstrated that short alkyl chain hydroxycinnamate esters which are used nowadays for FAE classification can lead to activity misclassification, while L-arabinose esters could potentially substitute synthetic esters in classification describing more adequately the enzyme specificitiesin the natural environment.

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  • 40.
    Antonopoulou, Io
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Use of feruloyl esterases for chemoenzymatic synthesis of bioactive compounds2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Feruloyl esterases (FAEs, EC 3.1.1.73) represent a subclass of carboxylic acid esterases that under normal conditions catalyze the hydrolysis of the ester bond between hydroxycinnamic acids (ferulic acid, sinapic acid, caffeic acid, p-coumaric acid) and arabinose residues in plant cell walls. Based on their specificity towards monoferulates and diferulates, substitutions on the phenolic ring and on their amino acid sequence identity, they have been classified into four types (A-D). The use of FAEs as accessory enzymes for the degradation of lignocellulosic biomass and their synergism with other hemicellulases has been studied for application in many industries, such as the food, the biofuel and the paper pulp industry. In the recent years, the use of FAEs as biosynthetic tools has been underlined. Under low water content, these enzymes are able to catalyze the esterification of hydroxycinnamic acids or the transesterification of their esters resulting in compounds with altered lipophilicity, revealing a great potential for tailor-made modification of natural antioxidants for use in cosmetic, cosmeceutical and pharmaceutical industries.

    The first part of the thesis is focused on the optimization of reaction conditions for the synthesis of two bioactive esters: prenyl ferulate and L-arabinose ferulate using 5 FAEs (FaeA1, FaeA2, FaeB1, FaeB2 and MtFae1a) from Myceliophthora thermophila in detergentless microemulsions. Reaction conditions were optimized investigating parameters such as the medium composition, the substrate concentration, the enzyme load, the pH, the temperature and the agitation. Regarding the synthesis of prenyl ferulate, FaeB2 offered the highest transesterification yield (71.5±0.2%) after 24 h of incubation at 30oC using 60 mM vinyl ferulate (VFA), 1 M prenol and 0.02 mg FAE/mL in a mixture comprising of 53.4: 43.4: 3.2 v/v/v n-hexane: t-butanol: 100 mM MOPS-NaOH pH 6.0. At these conditions, the competitive hydrolysis was 4-7 fold minimized. Regarding the synthesis of L-arabinose ferulate, FaeA1 offered highest transesterification yield (35.9±2.96%) after 8 h of incubation at 50oC using 80 mM VFA, 55 mM L-arabinose and 0.02 mg FAE/mL in a mixture of 19.8: 74.7: 5.5 v/v/v n-hexane: t-butanol: 100 mM MOPS-NaOH pH 8.0. It was revealed that the type B FAEs from M. thermophila show higher preference to more lipophilic acceptors like prenol, while the type A FaeA1 was more efficient in the synthesis of the more hydrophilic L-arabinose ferulate.

    The second part of the thesis is focused on the investigation of the basis of the type A classification of a well-studied FAE from Aspergillus niger (AnFaeA) by comparing its activity towards methyl and arabinose hydroxycinnamate esters. For this purpose, L-arabinose ferulate and caffeate were synthesized enzymatically. kcat/Km ratios revealed that AnFaeA hydrolyzed arabinose ferulate 1600 times and arabinose caffeate 6.5 times more efficiently than methyl esters. This study demonstrated that short alkyl chain hydroxycinnamate esters which are used nowadays for FAE classification can lead to activity misclassification, while L-arabinose esters could potentially substitute synthetic esters in classification.

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  • 41.
    Antonopoulou, Io
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Dilokpimol, Adiphol
    Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University.
    Iancu, Laura
    Dupont Industrial Biosciences.
    Mäkelä, Miia R.
    Department of Microbiology, University of Helsink.
    Varriale, Simona
    Department of Chemical Sciences, University of Naples “Federico II”.
    Cerullo, Gabriella
    Department of Chemical Sciences, University of Naples “Federico II”.
    Hüttner, Silvia
    Department of Biology and Biological Engineering, Division of Industrial Biotechnology, Chalmers University of Technology.
    Uthoff, Stefan
    Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster.
    Jütten, Peter
    Taros Chemicals GmbH & Co KG.
    Piechot, Alexander
    Taros Chemicals GmbH & Co KG.
    Steinbüchel, Alexander
    nstitut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster.
    Olsson, Lisbeth
    Department of Biology and Biological Engineering, Division of Industrial Biotechnology, Chalmers University of Technology.
    Faraco, Vincenza
    Department of Chemical Sciences, University of Naples “Federico II”.
    Hildén, Kristiina
    Department of Microbiology, University of Helsinki.
    de Vries, Ronald
    Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    The Synthetic Potential of Fungal Feruloyl Esterases: A Correlation with Current Classification Systems and Predicted Structural Properties2018Ingår i: Catalysts, E-ISSN 2073-4344, Vol. 8, nr 6, artikel-id 242Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Twenty-eight fungal feruloyl esterases (FAEs) were evaluated for their synthetic abilities in a ternary system of n-hexane: t-butanol: 100 mM MOPS-NaOH pH 6.0 forming detergentless microemulsions. Five main derivatives were synthesized, namely prenyl ferulate, prenyl caffeate, butyl ferulate, glyceryl ferulate, and l-arabinose ferulate, offering, in general, higher yields when more hydrophilic alcohol substitutions were used. Acetyl xylan esterase-related FAEs belonging to phylogenetic subfamilies (SF) 5 and 6 showed increased synthetic yields among tested enzymes. In particular, it was shown that FAEs belonging to SF6 generally transesterified aliphatic alcohols more efficiently while SF5 members preferred bulkier l-arabinose. Predicted surface properties and structural characteristics were correlated with the synthetic potential of selected tannase-related, acetyl-xylan-related, and lipase-related FAEs (SF1-2, -6, -7 members) based on homology modeling and small molecular docking simulations.

  • 42.
    Antonopoulou, Io
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hunt, Cameron
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Cerullo, Gabriella
    Department of Chemical Sciences, University of Naples "Federico II".
    Varriale, Simona
    Department of Chemical Sciences, University of Naples “Federico II”.
    Gerogianni, Alexandra
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Faraco, Vincenza
    Department of Chemical Sciences, University of Naples "Federico II".
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Tailoring the specificity of the type C feruloyl esterase FoFaeC from Fusarium oxysporum towards methyl sinapate by rational redesign based on small molecule docking simulations2018Ingår i: PLOS ONE, E-ISSN 1932-6203, Vol. 13, nr 5, artikel-id e0198127Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The type C feruloyl esterase FoFaeC from Fusarium oxysporum is a newly discovered enzyme with high potential for use in the hydrolysis of lignocellulosic biomass but it shows low activity towards sinapates. In this work, small molecule docking simulations were employed in order to identify important residues for the binding of the four model methyl esters of hydroxycinnamic acids, methyl ferulate/caffeate/sinapate/p-coumarate, to the predicted structure of FoFaeC. Subsequently rational redesign was applied to the enzyme’ active site in order to improve its specificity towards methyl sinapate. A double mutation (F230H/T202V) was considered to provide hydrophobic environment for stabilization of the methoxy substitution on sinapate and a larger binding pocket. Five mutant clones and the wild type were produced in Pichia pastoris and biochemically characterized. All clones showed improved activity, substrate affinity, catalytic efficiency and turnover rate compared to the wild type against methyl sinapate, with clone P13 showing a 5-fold improvement in catalytic efficiency. Although the affinity of all mutant clones was improved against the four model substrates, the catalytic efficiency and turnover rate decreased for the substrates containing a hydroxyl substitution.

  • 43.
    Antonopoulou, Io
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Iancu, Laura
    Dupont Industrial Biosciences, Wageningen, the Netherlands.
    Jütten, Peter
    Taros Chemicals GmbH & Co KG, Dortmund, Germany.
    Piechot, Alexander
    Taros Chemicals GmbH & Co KG, Dortmund, Germany.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Optimized Enzymatic Synthesis of Feruloyl Derivatives Catalyzed by Three Novel Feruloyl Esterases from Talaromyces wortmannii in Detergentless Microemulsions2018Ingår i: Computational and Structural Biotechnology Journal, E-ISSN 2001-0370, s. 361-369Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three novel feruloyl esterases (Fae125, Fae7262 and Fae68) from Talaromyces wortmanniioverexpressed in the C1 platform were evaluated for the transesterification of vinyl ferulatewith two acceptors of different size and lipophilicity (prenol and L-arabinose) in detergentless microemulsions. The effect of reaction conditions such as the microemulsion composition, the substrate concentration, the enzyme load, the pH, the temperature and the agitation were investigated. The type A Fae125 belonging to the subfamily 5 (SF5) of phylogenetic classification showed highest yields for the synthesis of both products after optimization of reaction conditions: 81.8% for prenyl ferulate and 33.0% for L-arabinose ferulate. After optimization, an 8-fold increase in the yield and a 12-fold increase in selectivity were achieved for the synthesis of prenyl ferulate.

  • 44.
    Antonopoulou, Io
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Iancu, Laura
    Dupont Industrial Biosciences.
    Jütten, Peter
    Taros Chemicals GmbH & Co KG.
    Piechot, Alexander
    Taros Chemicals GmbH & Co KG.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Screening of novel feruloyl esterases from Talaromyces wortmannii for the development of efficient and sustainable syntheses of feruloyl derivatives2019Ingår i: Enzyme and microbial technology, ISSN 0141-0229, E-ISSN 1879-0909, Vol. 120, s. 124-135Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The feruloyl esterases Fae125, Fae7262 and Fae68 from Talaromyces wortmannii were screened in 10 different solvent: buffer systems in terms of residual hydrolytic activity and of the ability for the transesterification of vinyl ferulate with prenol or L-arabinose. Among the tested enzymes, the acetyl xylan-related Fae125 belonging to the phylogenetic subfamily 5 showed highest yield and selectivity for both products in alkane: buffer systems (n-hexane or n-octane). Response surface methodology, based on a 5-level and 6-factor central composite design, revealed that the substrate molar ratio and the water content were the most significant variables for the bioconversion yield and selectivity. The effect of agitation, the possibility of DMSO addition and the increase of donor concentration were investigated. After optimization, competitive transesterification yields were obtained for prenyl ferulate (87.5-92.6%) and L-arabinose ferulate (56.2-61.7%) at reduced reaction times (≤ 24 h) resulting in good productivities (> 1 g/L/h, >300 kg product/kg FAE). The enzyme could be recycled for six consecutive cycles retaining 66.6% of the synthetic activity and 100% of the selectivity.

  • 45.
    Antonopoulou, Io
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Leonov, Laura
    DuPont Industrial Biosciences.
    Jûtten, Peter
    Taros Chemicals GmbH & Co.
    Cerullo, Gabriella
    Department of Chemical Sciences, University of Naples "Federico II".
    Faraco, Vincenza
    Department of Chemical Sciences, University of Naples "Federico II".
    Papadopoulou, Adamantia
    Institute of Biosciences and Applications NCSR "Demokritos," Laboratory of Cell Proliferation and Aging.
    Kletsas, Dimitris
    Institute of Biosciences and Applications NCSR "Demokritos," Laboratory of Cell Proliferation and Aging.
    Ralli, Marianna
    Korres Natural Products.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Optimized synthesis of novel prenyl ferulate performed by feruloyl esterases from Myceliophthora thermophila in microemulsions2017Ingår i: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 101, nr 8, s. 3213-3226Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Five feruloyl esterases (FAEs; EC 3.1.1.73), FaeA1, FaeA2, FaeB1, and FaeB2 from Myceliophthora thermophila C1 and MtFae1a from M. thermophila ATCC 42464, were tested for their ability to catalyze the transesterification of vinyl ferulate (VFA) with prenol in detergentless microemulsions. Reaction conditions were optimized investigating parameters such as the medium composition, the substrate concentration, the enzyme load, the pH, the temperature, and agitation. FaeB2 offered the highest transesterification yield (71.5 ± 0.2%) after 24 h of incubation at 30 °C using 60 mM VFA, 1 M prenol, and 0.02 mg FAE/mL in a mixture comprising of 53.4:43.4:3.2 v/v/v n-hexane:t-butanol:100 mM MOPS-NaOH, pH 6.0. At these conditions, the competitive side hydrolysis of VFA was 4.7-fold minimized. The ability of prenyl ferulate (PFA) and its corresponding ferulic acid (FA) to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals was significant and similar (IC50 423.39 μM for PFA, 329.9 μM for FA). PFA was not cytotoxic at 0.8–100 μM (IC50 220.23 μM) and reduced intracellular reactive oxygen species (ROS) in human skin fibroblasts at concentrations ranging between 4 and 20 μM as determined with the dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay.

  • 46.
    Antonopoulou, Io
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Papadopoulou, Adamantia
    Laboratory of Cell Proliferation & Ageing, Institute of Biosciences & Applications NCSR “Demokritos”, T. Patriarchou Grigoriou & Neapoleos.
    Iancu, Laura
    DuPont Industrial Biosciences.
    Cerullo, Gabriella
    Department of Chemical Sciences, University of Naples "Federico II".
    Ralli, Marianna
    Korres Natural Products.
    Jûtten, Peter
    Taros Chemicals GmbH & Co.
    Piechot, Alexander
    Taros Chemicals GmbH & Co.
    Faraco, Vincenza
    Department of Chemical Sciences, University of Naples "Federico II".
    Kletsas, Dimitris
    Institute of Biosciences and Applications NCSR "Demokritos," Laboratory of Cell Proliferation and Aging.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Optimization of enzymatic synthesis of l-arabinose ferulate catalyzed by feruloyl esterases from Myceliophthora thermophila in detergentless microemulsions and assessment of its antioxidant and cytotoxicity activities2018Ingår i: Process Biochemistry, ISSN 1359-5113, E-ISSN 1873-3298, Vol. 65, s. 100-108Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The feruloyl esterases FaeA1, FaeA2, FaeB1, FaeB2 from Myceliophthora thermophila C1 and MtFae1a from M. thermophila ATCC 42464 were used as biocatalysts for the transesterification of vinyl ferulate (VFA) with l-arabinose in detergentless microemulsions. The effect of parameters such as the microemulsion composition, the substrate concentration, the enzyme load, the pH, the temperature and the agitation was investigated. FaeA1 offered the highest transesterification yield (52.2 ± 4.3%) after 8 h of incubation at 50 °C using 80 mM VFA, 55 mM l-arabinose and 0.02 mg FAE mL−1 in a mixture comprising of 19.8: 74.7: 5.5 v/v/v n-hexane: t-butanol: 100 mM MOPS-NaOH pH 8.0. The ability of l-arabinose ferulate (AFA) to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals was significant (IC50 386.5 μM). AFA was not cytotoxic even at high concentrations (1 mM) however was found to be pro-oxidant at concentrations higher than 20 μM when the antioxidant activity was determined with the dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay in human skin fibroblasts.

  • 47.
    Antonopoulou, Io
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    CO2 to Methanol: A Highly Efficient Enzyme Cascade2022Ingår i: Multienzymatic Assemblies: Methods and Protocols / [ed] Haralambos Stamatis, Springer Nature, 2022, 1, s. 317-344Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Carbon dioxide (CO2) has been increasingly regarded not only as a greenhouse gas but also as a valuable feedstock for carbon-based chemicals. In particular, biological approaches have drawn attention as models for the production of value-added products, as CO2 conversion serves many natural processes. Enzymatic CO2 reduction in vitro is a very promising route to produce fossil free and bio-based fuel alternatives, such as methanol. In this chapter, the advances in constructing competitive multi-enzymatic systems for the reduction of CO2 to methanol are discussed. Different integrated methods are presented, aiming to address technological challenges, such as the cost effectiveness, need for material regeneration and reuse and improving product yields of the process.

  • 48.
    Antonopoulou, Io
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sapountzaki, Eleftheria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ferulic Acid From Plant Biomass: A Phytochemical With Promising Antiviral Properties2022Ingår i: Frontiers in Nutrition, E-ISSN 2296-861X, Vol. 8, artikel-id 777576Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Plant biomass is a magnificent renewable resource for phytochemicals that carry bioactive properties. Ferulic acid (FA) is a hydroxycinnamic acid that is found widespread in plant cell walls, mainly esterified to polysaccharides. It is well known of its strong antioxidant activity, together with numerous properties, such as antimicrobial, anti-inflammatory and neuroprotective effects. This review article provides insights into the potential for valorization of FA as a potent antiviral agent. Its pharmacokinetic properties (absorption, metabolism, distribution and excretion) and the proposed mechanisms that are purported to provide antiviral activity are presented. Novel strategies on extraction and derivatization routes, for enhancing even further the antiviral activity of FA and potentially favor its metabolism, distribution and residence time in the human body, are discussed. These routes may lead to novel high-added value biorefinery pathways to utilize plant biomass toward the production of nutraceuticals as functional foods with attractive bioactive properties, such as enhancing immunity toward viral infections.

  • 49.
    Antonopoulou, Io
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sapountzaki, Eleftheria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Inhibition of the main protease of SARS-CoV-2 (Mpro) by repurposing/designing drug-like substances and utilizing nature’s toolbox of bioactive compounds2022Ingår i: Computational and Structural Biotechnology Journal, ISSN 2001-0370, Vol. 20, s. 1306-1344Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The emergence of the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has resulted in a long pandemic, with numerous cases and victims worldwide and enormous consequences on social and economic life. Although vaccinations have proceeded and provide a valuable shield against the virus, the approved drugs are limited and it is crucial that further ways to combat infection are developed, that can also act against potential mutations. The main protease (Mpro) of the virus is an appealing target for the development of inhibitors, due to its importance in the viral life cycle and its high conservation among different coronaviruses. Several compounds have shown inhibitory potential against Mpro, both in silico and in vitro, with few of them also having entered clinical trials. These candidates include: known drugs that have been repurposed, molecules specifically designed based on the natural substrate of the protease or on structural moieties that have shown high binding affinity to the protease active site, as well as naturally derived compounds, either isolated or in plant extracts. The aim of this work is to collectively present the results of research regarding Mpro inhibitors to date, focusing on the function of the compounds founded by in silico simulations and further explored by in vitro and in vivo assays. Creating an extended portfolio of promising compounds that may block viral replication by inhibiting Mpro and by understanding involved structure–activity relationships, could provide a basis for the development of effective solutions against SARS-CoV-2 and future related outbreaks.

  • 50.
    Antonopoulou, Io
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sapountzaki, Eleftheria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    The Inhibitory Potential of Ferulic Acid Derivatives against the SARS-CoV-2 Main Protease: Molecular Docking, Molecular Dynamics, and ADMET Evaluation2022Ingår i: Biomedicines, E-ISSN 2227-9059, Vol. 10, nr 8, artikel-id 1787Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The main protease (Mpro) of SARS-CoV-2 is an appealing target for the development of antiviral compounds, due to its critical role in the viral life cycle and its high conservation among different coronaviruses and the continuously emerging mutants of SARS-CoV-2. Ferulic acid (FA) is a phytochemical with several health benefits that is abundant in plant biomass and has been used as a basis for the enzymatic or chemical synthesis of derivatives with improved properties, including antiviral activity against a range of viruses. This study tested 54 reported FA derivatives for their inhibitory potential against Mpro by in silico simulations. Molecular docking was performed using Autodock Vina, resulting in comparable or better binding affinities for 14 compounds compared to the known inhibitors N3 and GC376. ADMET analysis showed limited bioavailability but significantly improved the solubility for the enzymatically synthesized hits while better bioavailability and druglikeness properties but higher toxicity were observed for the chemically synthesized ones. MD simulations confirmed the stability of the complexes of the most promising compounds with Mpro, highlighting FA rutinoside and compound e27 as the best candidates from each derivative category.

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