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  • 151.
    Hassan, Mohsan
    et al.
    Department of Mathematics, COMSATS University Islamabad, Lahore Campus, Lahore, Pakistan.
    Faisal, Abrar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Department of Chemical Engineering, COMSATS University Islamabad, Lahore Campus, Lahore, Pakistan.
    Ali, Irfan
    Department of Mathematics, Sukkur Institute of Business Administration, Sindh, Pakistan.
    Bhatti, Muhammad Mubashir
    Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai, China.
    Yousaf, Muhammad
    Department of Mathematics, COMSATS University Islamabad, Lahore Campus, Lahore, Pakistan.
    Effects of Cu–Ag hybrid nanoparticles on the momentum and thermal boundary layer flow over the wedge2019Inngår i: Proceedings of the Institution of mechanical engineers. Part E, journal of process mechanical engineering, ISSN 0954-4089, E-ISSN 2041-3009, Vol. 233, nr 5, s. 1128-1136Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, the effects of hybrid nanoparticles on the momentum and thermal boundary layers as well as flow characteristics and thermal performance of the hybrid nanofluid are investigated over the wedge. The fluid in the enclosure is water containing hybrid nanoparticles Cu–Ag. The physical model of homogenous hybrid nanofluid is derived using the elementary equations of thermo-hydrodynamic and co-relation's model of a mixture that supports the effective physical features. The results are calculated to measure the effects of nanoparticle concentration on thermal and momentum boundary layers and displayed in graphs for discussions. In addition, the effects of nanoparticles concentration and different compositions of hybrid nanoparticles on temperature and velocity profiles, physical properties, skin friction, and convective heat transfer coefficient are deliberated through graphs and tables. To check its heat transfer performance, a comparison of hybrid nanofluid is made between the base fluid and single material nanofluids. It is found that the efficiency of hybrid nanofluids as a heat transfer fluid is much more than conventional fluids or single nanoparticles-based nanofluids. These results in terms of boundary layers phenomena, heat transfer performance, and temperature and velocity profiles under hybrid nanomaterial could help chemical engineers to design the critical equipment in a process industry such as heat exchangers and pumps and others.

  • 152.
    Hassan, Mohsan
    et al.
    Department of Mathematics, CIIT, Lahore, Pakistan .
    Faisal, Abrar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Department of Chemical Engineering, CIIT, Lahore, Pakistan.
    Bhatti, Muhammad Mubashir
    Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai, China.
    Interaction of aluminum oxide nanoparticles with flow of polyvinyl alcohol solutions base nanofluids over a wedge2018Inngår i: Applied Nanoscience, ISSN 2190-5509, E-ISSN 2190-5517, Vol. 8, nr 1-2, s. 53-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polyvinyl alcohol (PVA) is an important industrial chemical, which is used in numerous chemical engineering applications. It is important to study and predict the flow behavior of PVA solutions and the role of nanoparticles in heat transfer applications to be used in chemical processes on industrial scale. Therefore, the present study deals with the PVA solution-based non-Newtonian Al2O3-nanofluid flow along with heat transfer over wedge. The power-law model is used for this non-Newtonian nanofluid which exhibited shear-thinning behavior. The influences of PVA and nanoparticles concentrations on the characteristics of velocity and temperature profiles are examined graphically. The impacts of these parameters on wall shear stress and convective heat transfer coefficient are also studied through tabular form. During the numerical computations, the impacts of these parameters on flow index and consistency index along with other physical properties of nanofluid are also considered. In this study, we found an improvement in heat transfer and temperature profile of fluid by distribution of Al2O3 nanoparticles. It is also noticed that resistance between adjacent layers of moving fluid is enhanced due to these nanoparticles which leads to decline in velocity profile and increases in shear stress at wall.

  • 153.
    Hedlund, Jonas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Yu, Liang
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Nobandegani, Mojtaba
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Diffusion of small molecules in ultra-thin MFI membranes2019Konferansepaper (Fagfellevurdert)
  • 154.
    Hedlund, Jonas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Yu, Liang
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sinaei Nobandegani, Mojtaba
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Diffusion of small molecules in ultra-thin MFI membranes2019Konferansepaper (Fagfellevurdert)
  • 155.
    Holmgren, Allan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Lidström-Larsson, Margareta
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sterte, Johan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Wang, Zheng
    Luleå tekniska universitet.
    Sensor for spectroscopic analysis of gases or liquids, comprises attenuated total reflection element with molecular sieve layerPatent (Annet (populærvitenskap, debatt, mm))
  • 156.
    Hruzova, Katerina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Patel, Alok
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Masák, Jan
    Department of Biotechnology, University of Chemistry and Technology Prague, Prague, Czech Republic.
    Maťátková, Olga
    Department of Biotechnology, University of Chemistry and Technology Prague, Prague, Czech Republic.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    A novel approach for the production of green biosurfactant from Pseudomonas aeruginosa using renewable forest biomass2020Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 711, artikkel-id 135099Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The rising demand for surfactants by the pharmaceuticals and cosmetic industries has generated vast amounts of petroleum-based synthetic surfactants, which are often toxic and non-degradable. Owing to their low toxicity, stability in extreme conditions, and biodegradability, biosurfactants could represent a sustainable alternative. The present study aimed to maximize the production of rhamnolipids (RL) from Pseudomonas aeruginosa by optimizing glucose concentration, temperature, and C/N and C/P ratios. After 96 h of cultivation at 37 °C, the final RL concentration was 4.18 ± 0.19 g/L with a final yield of 0.214 ± 0.010 g/gglucose when pure glucose was used as a carbon source. At present, the main obstacle towards commercialization of RL production is economic sustainability, due to the high cost of downstream processes and media components. For this reason, a renewable source such as wood hydrolysates (from birch and spruce woodchips) was examined here as a possible source of glucose for RL production. Both hydrolysates proved to be adequate, resulting in 2.34 ± 0.17 and 2.31 ± 0.10 g/L of RL, respectively, and corresponding yields of 0.081 ± 0.006 and 0.089 ± 0.004 g/gsugar after 96 h. These results demonstrate the potential of using renewable biomass for the production of biosurfactants and, to the best of our knowledge, they constitute the first report on the use of wood hydrolysates for RL production.

  • 157.
    Hua, Jing
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Björling, Marcus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Shi, Yijun
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    A smart friction control strategy enabled by CO2 absorption and desorption2019Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, nr 1, artikkel-id 13262Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Intelligent control of friction is an attractive but challenging topic and it has rarely been investigated for full size engineering applications. In this work, it is instigated if it would be possible to adjust friction by controlling viscosity in a lubricated contact. By exploiting the ability to adjust the viscosity of the switchable ionic liquids, 1,8-Diazabicyclo (5.4.0) undec-7-ene (DBU)/ glycerol mixture via the addition of CO2, the friction could be controlled in the elastohydrodynamic lubrication (EHL) regime. The friction decreased with increasing the amount of CO2 to the lubricant and increased after partial releasing CO2. As CO2 was absorbed by the liquid, the viscosity of the liquid increased which resulted in that the film thickness increased. At the same time the pressure-viscosity coefficient decreased with the addition of CO2. When CO2 was released again the friction increased and it was thus possible to control friction by adding or removing CO2.

  • 158.
    Huang, Rick K.
    et al.
    Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal, and Skin Diseases, National Institutes of Health, Bethesda, Maryland.
    Baxa, Ulrich
    Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal, and Skin Diseases, National Institutes of Health, Bethesda, Maryland.
    Aldrian, Gudrun
    Centre de Recherches de Biochimie Macromoléculaire, CNRS, University of Montpellier 1 and 2.
    Ahmed, Abdullah B.
    Centre de Recherches de Biochimie Macromoléculaire, CNRS, University of Montpellier 1 and 2.
    Wall, Joseph P.
    Department of Biology, Brookhaven National Laboratory, Upton New York.
    Mizuno, Naoko
    Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal, and Skin Diseases, National Institutes of Health, Bethesda, Maryland.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Steven, Alasdair C.
    Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal, and Skin Diseases, National Institutes of Health, Bethesda, Maryland.
    Kajava, Andrey V.
    Centre de Recherches de Biochimie Macromoléculaire, CNRS, University of Montpellier 1 and 2.
    Conformational Switching in PolyGln Amyloid Fibrils Resulting from a Single Amino Acid Insertion2014Inngår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 106, nr 10, s. 2134-2142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The established correlation between neurodegenerative disorders and intracerebral deposition of polyglutamine aggregates motivates attempts to better understand their fibrillar structure. We designed polyglutamines with a few lysines inserted to overcome the hindrance of extreme insolubility and two D-lysines to limit the lengths of β-strands. One is 33 amino acids long (PolyQKd-33) and the other has one fewer glutamine (PolyQKd-32). Both form well-dispersed fibrils suitable for analysis by electron microscopy. Electron diffraction confirmed cross-β structures in both fibrils. Remarkably, the deletion of just one glutamine residue from the middle of the peptide leads to substantially different amyloid structures. PolyQKd-32 fibrils are consistently 10–20% wider than PolyQKd-33, as measured by negative staining, cryo-electron microscopy, and scanning transmission electron microscopy. Scanning transmission electron microscopy analysis revealed that the PolyQKd-32 fibrils have 50% higher mass-per-length than PolyQKd-33. This distinction can be explained by a superpleated β-structure model for PolyQKd-33 and a model with two β-solenoid protofibrils for PolyQKd-32. These data provide evidence for β-arch-containing structures in polyglutamine fibrils and open future possibilities for structure-based drug design.

  • 159.
    Hunt, Cameron J
    et al.
    Department of Chemical Engineering, Monash University, Clayton, 3800, Victoria, Australia..
    Antonopoulou, Io
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Tanksale, Akshat
    Department of Chemical Engineering, Monash University, Clayton, 3800, Victoria, Australia..
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Haritos, Victoria S
    Department of Chemical Engineering, Monash University, Clayton, 3800, Victoria, Australia.
    Insights into substrate binding of ferulic acid esterases by arabinose and methyl hydroxycinnamate esters and molecular docking2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, nr 1, artikkel-id 17315Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ferulic acid esterases (FAE, EC 3.1.1.73) cleave the arabinose hydroxycinnamate ester in plant hemicellulose and other related substrates. FAE are commonly categorised as type A-D based on catalytic activities towards model, short alkyl chain esters of hydroxycinnamates. However, this system correlates poorly with sequence and structural features of the enzymes. In this study, we investigated the basis of the type A categorisation of an FAE from Aspergillus niger, AnFaeA, by comparing its activity toward methyl and arabinose hydroxycinnamate esters. kcat/Km ratios revealed that AnFaeA hydrolysed arabinose ferulate 1600-fold, and arabinose caffeate 6.5 times more efficiently than their methyl ester counterparts. Furthermore, small docking studies showed that while all substrates adopted a catalytic orientation with requisite proximity to the catalytic serine, methyl caffeate and methyl p-coumarate preferentially formed alternative non-catalytic conformations that were energetically favoured. Arabinose ferulate was unable to adopt the alternative conformation while arabinose caffeate preferred the catalytic orientation. This study demonstrates that use of short alkyl chain hydroxycinnnamate esters can result in activity misclassification. The findings of this study provide a basis for developing a robust classification system for FAE and form the basis of sequence-function relationships for this class.

  • 160.
    Häggström, Caroline
    et al.
    Wibax AB.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Brandberg, Tomas
    SEKAB E-Technology, School of Engineering, University of Borås.
    Hodge, David
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Integration of Ethanol Fermentation with Second Generation Biofuels Technologies2014Inngår i: Biorefineries: Integrated Biochemical Processes for Liquid Biofuels, Amsterdam: Elsevier, 2014, s. 161-187Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    This chapter presents an overview of the challenges associated with integrating yeast fermentation into cellulosic biofuel processes, as well as the approaches that might overcome these challenges. The chapter first introduces the design considerations for first-generation ethanol fermentation processes using sugar cane and corn as feedstocks, with an emphasis on process constraints and operation strategies. The chapter then explores methods for improving yield, titer, productivity, and economics. These processing methods illustrate the challenges posed by the fermentation of ethanol from lignocellulose hydrolyzates, especially the differences in process constraints for high-productivity, high-product titer operations. Finally, the chapter discusses an example of aerobic seed cultivation of yeast using a hydrolyzate of dilute acid-hydrolyzed softwood hemicellulose

  • 161.
    Högström, Åsa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sulfur poisoning and regeneration of copper zeolites for NH3-SCR: Effect of SO2/SO3 ratio2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The road transportation is a big source for the release of NOx emissions. NOx has been confirmed to cause negative affect on the air-quality especially in the urban areas, there are therefore regulations for allowed released amount from vehicles. The most adopted technology used for the reduction of these NOx emissions from the diesel exhaust gas is the ammonium selective catalytic reduction (NH3-SCR) using a Cu-zeolite as the catalyst in the system.

    The SCR catalyst can be deactivated through different mechanism, whereas poisoning by sulfur has been documented to be an important factor for the deactivation. The degree of deactivation of the catalyst has been suggested to vary depending on the catalytic material and which sulfur conditions the catalyst is exposed to, where SO3 has been indicated to cause more sever deactivation compared to SO2.

     The aim of this project has been to investigate the deactivation mechanism of Cu-zeolites at different SOx conditions and evaluate potential regeneration mechanism. The project was carried out by evaluating the catalysts, Cu-BEA and Cu-SSZ-13, over different reactions that occurs in the SCR system, investigating the deactivation effect caused by SO2 poisoning and the regeneration potential. The project was then continued with the focus on the Cu-SSZ-13 catalyst investigating different SOx poisoning and regeneration conditions were investigated. In order to investigate the SO3 poisoning a generator using oxidation of SO2 to SO3 was successfully build during this project.  A kinetic model over the Cu-SSZ-13 NH3-SCR reactions was also built based on literature studies and the experimental data obtained. The results from the sulfur poisoning of Cu-BEA are based on the master thesis by Maria Arvanitidou.

    The fresh samples Cu-Beta and Cu-SSZ-13 exhibited similar activity, with the exception of the high formation of N2O observed over Cu-Beta under SCR conditions. The SO2 causes deactivation, especially at low temperatures. Cu-SSZ-13 exhibited more loss in activity but was able to recover more through the elevated SCR regeneration steps than the Cu-Beta. When SO2 exposure was performed together with NH3, larger deactivation was observed, likely due to ammonium sulfate species formed on the surface. The ammonium sulfate species were less thermally stable than copper sulfates, making it easier to recover the loss of activity in the Cu-SSZ-13. SO3 caused a much more sever deactivation of the SCR reactions than that of the SO2 poisoning and continued to show the lowest NOx removal activity after the regeneration process.  A difference in initial deactivation and recovery of activity between standard and fast SCR reactions was observed, indicating that the different mechanisms used are affected differently by the poisoning. The kinetic model for NH3-SCR over the Cu-SSZ-13 was successfully created when compared to the experimentally obtained data.

  • 162.
    Ivanov, Alexander V.
    et al.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences, Blagoveshchensk.
    Bredyuk, O.A.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences, Blagoveshchensk.
    Loseva, Olga V.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences, Blagoveshchensk.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Synthesis, Supramolecular Self-Organization, and Thermal Behavior of Gold(III)–Thallium(III) Heteronuclear Complexes ([Au{S2CN(CH3)2}2][TlCl4])2 and ([Au{S2CN(C2H5)2}2][TlCl4]) n2016Inngår i: Russian Journal of Inorganic Chemistry, ISSN 0036-0236, E-ISSN 1531-8613, Vol. 61, nr 6, s. 755-765Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interaction of polymeric thallium(I) dimethyl- and diethyldithiocarbamates with [AuCl4]– in 2 M HCl has been studied. Heteropolynuclear complexes ([Au{S2CN(CH3)2}2][TlCl4])2 (I) and ([Au{S2CN(C2H5)2}2][TlCl4]) n (II) have been preparatively isolated from chemisorption systems [Tl2{S2CNR2}2] n –Au3+/2 M HCl (R = CH3, C2H5). These compounds have been characterized by 13C CP/MAS NMR, and their crystal and supramolecular structures have been determined by X-ray crystallography. Basic structural units of compounds I and II are square-planar [Au{S2CNR2}2]+ cations (with S,S'- bidentate coordination of two Dtc ligands to the gold atom) and distorted tetrahedral [TlCl4]–anions. In supramolecular self-organization, the decisive role is played by relatively weak secondary interactions Au⋯S and Au⋯Cl. With the use of simultaneous thermal analysis, the thermal behavior of I and II have been studied, which enabled the elucidation of temperature-induced transformations and identification of TlCl and reduced gold among the thermolysis products.

  • 163.
    Ivanov, Alexander V.
    et al.
    Institute of Geology and Nature Management, Far Eastern Branch of the Russian Academy of Sciences .
    Gerasimenko, A.V.
    Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences.
    Egorova, I.V.
    Blagoveshchensk State Pedagogical University.
    Zaeva, A.S.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences.
    Novikova, E.V.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences.
    Rodionova, N.A.
    Blagoveshchensk State Pedagogical University.
    Gowda, V.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. University of Oulu.
    Antzutkin, O.N.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Warwick University.
    Chemisorption Synthesis of the Ion-Polymeric Heteronuclear Gold(III)-Bismuth(III) Complex ([Au{S2CN(C3H7)2}2]3[Bi2Cl9])n Based on [Bi2{S2CN(C3H7)2}6]: 13C MAS NMR, Supramolecular Structure, and Thermal Behavior2018Inngår i: Russian journal of coordination chemistry, ISSN 1070-3284, E-ISSN 1608-3318, Vol. 44, nr 8, s. 518-531Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Chemisorption synthesis on the basis of the binuclear compound [Bi2{S2CN(C3H7)2}6] (I) and preparative isolation of the ion-polymeric heteronuclear gold(III)-bismuth(III) complex ([Au{S2CN(C3H7)2}2]3[Bi2Cl9])n (II) are carried out. Compounds I and II are characterized in comparison by IR spectroscopy and 13C CP-MAS NMR. According to the X-ray diffraction analysis data (CIF file CCDC no. 1407705), the cationic moiety of compound II exhibits an unusually complicated supramolecular structure including six isomeric noncentrosymmetric complex cations [Au{S2CN(C3H7)2}2]+ (hereinafter A-F) and two binuclear anions [Bi2Cl9]3- as conformers. The isomeric gold(III) cations perform various structural functions. Owing to pair secondary interactions Au···S, cations B, C, E, and F form centrosymmetric ([E···E], [F···F]) and noncentrosymmetric ([B···C]) binuclear aggregates [Au2{S2CN(C3H7)2}4]2+, whereas cations A and D are not involved in dimerization. The strongest secondary Au···S bonds are formed between the binuclear and mononuclear cations, resulting in the formation of supramolecular cation-cationic polymer chains of two types: (⋅⋅⋅A⋅⋅⋅[B⋅⋅⋅C]⋅⋅⋅A⋅⋅⋅[B⋅⋅⋅C]⋅⋅⋅)n and (D⋅⋅⋅[E⋅⋅⋅E]⋅⋅⋅D⋅⋅⋅[F⋅⋅⋅F]⋅⋅⋅])n. In both chains, the gold atoms of the binuclear cations are characterized by a distorted octahedral coordination [S6], whereas in the mononuclear cations the gold atoms retain the square environment [S4]. The cation-anionic interactions are provided by secondary bonds Cl⋅⋅⋅S involving the terminal chlorine atoms of isomeric [Bi2Cl9]3- and the sulfur atoms of the binuclear cations [Au2{S2CN(C3H7)2}4]2+. The character of the thermal behavior of compounds I and II is studied by simultaneous thermal analysis with the identification of intermediate and final products of the thermal transformations. The thermolysis of compound I at 193-320°C is accompanied by the formation of Bi2S3 with an impurity of reduced metallic bismuth particles. The final products of the thermal transformations of compound II are reduced elemental gold and Bi2O3, and the thermal transformation intermediates are BiCl3 and Bi2S3.

  • 164.
    Ivanov, A.V.
    et al.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences, Blagoveshchensk.
    Egorova, I.V.
    Blagoveshchensk State Pedagogical University.
    Ivanov, M.A.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences, Blagoveshchensk.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Tsvykh, R.S.
    University of Warwick, Coventry.
    Structure of crystalline bismuth(III) N,N-dipropyldithiocarbamate [Bi{S2CN(C3H7)2}3] according to 13C and 15N MAS NMR and X-ray diffraction analysis: Supramolecular self-organization and conformational isomerism2014Inngår i: Doklady. Physical chemistry, ISSN 0012-5016, E-ISSN 1608-3121, Vol. 454, nr 1, s. 16-20Artikkel i tidsskrift (Fagfellevurdert)
  • 165.
    Ivanov, Maxim A.
    et al.
    Institute of Geology and Nature Management, Far Eastern Branch of the Russian Academy of Sciences.
    Larsson, Anna-Carin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Ivanov, Alexander V.
    Institute of Geology and Nature Management, Far Eastern Branch of the Russian Academy of Sciences .
    Gerasimenko, Andrey V.
    Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences.
    Merkulov, Eugene B.
    Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences.
    An example of S,S′-bidentate coordination mode of the dithiophosphate group in the heteroleptic tetraphenylantimony(V) complex, [Sb(C6H5)4{S2P(O-cyclo-C6H11)2}]: multinuclear (13C, 31P) CP MAS NMR, single-crystal X-ray diffraction studies and thermal behaviour2017Inngår i: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Crystalline O,O′-di-cyclo-hexyl dithiophosphate (Dtph) tetraphenylantimony(V) complex, [Sb(C6H5)4{S2P(O-cyclo-C6H11)2}] (1) was prepared and studied by means of heteronuclear (31C, 31P) CP MAS NMR spectroscopy, single-crystal X-ray diffraction and thermal analysis. To characterise quantitatively the phosphorous site in complex 1, 31P chemical shift anisotropy parameters (δaniso and η) were successfully defined from spinning sideband manifolds in experimental MAS NMR spectra. The positive sign of the calculated δaniso unambiguously reveals the terminal S,S′-chelating structural function of di-cyclo-hexyl Dtph groups; whereas, the minimal δ22 value among all presently known tetraphenylantimony(V) dialkyl Dtphs points out to extremely low value of the S–P–S angle. Distorted octahedral molecular structure comprising Dtph ligand with S,S′-bidentate chelating coordination mode has been established for the prepared complex. Therefore, in comparison with tetraphenylantimony(V) Dtph complexes containing S-unidentately coordinated Dtph groups, terminally chelating di-cyclo-hexyl Dtph ligand of crystalline complex 1 expectedly exhibits the smallest S–P–S angle of 113.49°. The thermal behaviour of this compound was studied by means of thermal analysis technique as a combination of TG and DSC. The thermal decomposition involves the organic and inorganic parts of 1, yielding almost equal quantities of Sb2S3 and SbPO4, which were identified using powder XRD.

  • 166.
    Javed, Muhammad Asadullah
    et al.
    NMR Research Unit, University of Oulu.
    Ahola, Susanna
    NMR Research Unit, University of Oulu.
    Håkansson, Pär
    NMR Research Unit, University of Oulu.
    Mankinen, Otto
    NMR Research Unit, University of Oulu.
    Aslam, Muhammad Kamran
    NMR Research Unit, University of Oulu.
    Filippov, Andrei
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Glavatskih, Sergei
    System and Component Design, Department of Machine Design, KTH Royal Institute of Technology.
    Antzutkin, Oleg N.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Telkki, Ville-Veikko
    NMR Research Unit, University of Oulu.
    Y Structure and dynamics elucidation of ionic liquids using multidimensional Laplace NMR2017Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, nr 80, s. 11056-11059Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate the ability of multidimensional Laplace NMR (LNMR), comprising relaxation and diffusion experiments, to reveal essential information about microscopic phase structures and dynamics of ionic liquids that is not observable using conventional NMR spectroscopy or other techniques.

  • 167.
    Johansson, Ann-Christine
    et al.
    RISE Energy Technology Center AB.
    Sandström, Linda
    RISE Energy Technology Center AB.
    Öhrman, Olov
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. RISE Energy Technology Center AB.
    Jilvero, Hanrik
    Stena Metall.
    Co-pyrolysis of woody biomass and plastic waste in both analytical and pilot scale2018Inngår i: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 134, s. 102-113Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Earlier studies show that co-pyrolysis of biomass and plastics can improve the quantity and quality of the produced pyrolysis oil compared to pyrolysis of the separate feedstocks. In this work three relevant plastic wastes; paper reject, shredder light fraction and cable plastics; were evaluated together with woody biomass (stem wood from spruce and pine) using analytical pyrolysis, Py-GC-MS/FID. One verification experiment was also conducted in a cyclone pyrolyser pilot plant at industrially relevant conditions.

    The addition of plastic waste to woody biomass pyrolysis was found to significantly affect the composition and properties of the produced pyrolysis products. In analytical pyrolysis experiments, positive synergetic effects were observed in the co-pyrolysis of paper reject and cable plastics together with the stem wood. The yield of reactive oxygenated compounds (ketones, aldehydes and acids) was suppressed while more stable alcohols and esters were promoted. The formation of hydrocarbons was also promoted in the co-pyrolysis of plastics from paper reject and stem wood. The results from the analytical pyrolysis were partly verified in the pilot scale experiment by co-pyrolysing stem wood and paper reject. However, the co-pyrolysis also affected other parameters that cannot be detected in analytical pyrolysis such as higher acidity and viscosity of the oil which highlights the need for undertaking experiments at different scales. The product yields in pilot scale were about the same for the co-pyrolysis case as for pure stem wood. However, a high volatile content of the solid product indicated that the process conditions can be further optimized for co-pyrolysing cases.

  • 168.
    Johansson, Simon
    et al.
    Nestec Ltd, Nestlé Research Center.
    Diehl, Bernd
    Spectral Services AG, Köln.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Austin, Sean
    Nestec Ltd, Nestlé Research Center.
    Vafialdi, Christina
    Nestec Ltd, Nestlé Research Center.
    Oligosaccharide synthesis in Fruit Juice Concentrates using a Glucansucrase from Lactobacillus reuteri 1802016Inngår i: Food and Bioproducts Processing, ISSN 0960-3085, E-ISSN 1744-3571, Vol. 98, s. 201-209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The application of the glucansucrase GTF180 from Lactobacillus reuteri 180 in fruit juice concentrates for the synthesis of glucooligosaccharides was investigated. Reaction parameters such as temperature, pH, substrate and enzyme loading, Ca+2 addition and incubation time were investigated in high concentration sucrose solutions. The optimum conditions (50 °C, pH 4.5, enzyme loading 14.47 U/gsucrose with 1 mM CaCl2, undiluted fruit juice concentrates) were applied in apple and orange juice concentrates. More than 95% of the intrinsic sucrose was converted to oligosaccharide products after 90 min. The main products were leucrose, isomaltose and isomaltotriose. The enzyme was deactivated during standard fruit juice pasteurization conditions (95 °C, 15 sec). The oligosaccharides were stable during the pasteurization process, showing a good potential for industrial applications. DOSY NMR analysis of the enzymatically modified fruit juice concentrates showed that α1→6 glycosidic linkages are predominant in apple juice, while products in orange juice possess both α1→6 and α1→3 glycosidic linkages. The presence of α1→2 glycosidic linkages were also observed at a lower extent

  • 169.
    Ju, Minhua
    et al.
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University.
    Li, Yupeng
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University.
    Yu, Liang
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Wang, Chongqing
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing.
    Zhang, Lixiong
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing.
    Preparation of size-controllable monodispersed carbon@silica core-shell microspheres and hollow silica microspheres2017Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 247, s. 75-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Size-controllable monodispersed carbon@silica core-shell microspheres and hollow silica microspheres were prepared in a simple homemade T-type mixer by polymerization of furfuryl alcohol (FA) and hydrolysis of TEOS in H2SO4 water phase microdroplets to obtain polyfurfuryl alcohol (PFA)@silica microspheres, followed by carbonization and calcination. The FA and TEOS diffuse into the water phase from an oil phase. The flow rates of oil and water phase were 4 and 2 ml h−1, respectively. It was found that the concentration of FA has a more significant effect on the diameter of carbon@silica core-shell microspheres than TEOS due to the template effect of the PFA core. However, the diameter of the hollow silica microspheres was influenced by the concentration of TEOS more significantly. The obtained core-shell microspheres and hollow silica microspheres have large surface area of 555 and 769 m2 g−1, respectively. The hollow silica microspheres have both microporous and mesoporous structure, and the percentage of mesoporous volume was as high as 89%. In addition, based on the study results, a rational formation process of the carbon@silica core-shell microsphere and hollow silica microspheres was assumed.

  • 170.
    Ju, Minhua
    et al.
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University , P. R. China.
    Li, Yupeng
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University , P. R. China.
    Yu, Liang
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Wang, Chongqing
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University , P. R. China.
    Zhang, Lixiong
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University , P. R. China.
    Two-Phase Diffusion Technique for the Preparation of Ultramacroporous/Mesoporous Silica Microspheres via Interface Hydrolysis, Diffusion, and Gelation of TEOS2018Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 34, nr 5, s. 2046-2056Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Honeycombed hierarchical ultramacroporous/mesoporous silica microspheres were prepared via the hydrolysis of TEOS in the oil-water interface, with subsequent diffusion and gelation in the acidic water-phase microdroplets with the assistance of a simple homemade microdevice. The diffusion of furfuryl alcohol (FA) also happened at a relatively high rate during the hydrolysis and diffusion of TEOS. Therefore, plenty of FA will be inside of the water microdroplets and form a decent number of polyfurfuryl alcohol (PFA) microparticles, thereby obtaining honeycombed hierarchical porosity silica microspheres with abundant ultramacroporous cavities and mesopores after calcination. It was found that the concentration of FA, residence time, and reaction temperature have significant effects on the porosity and pore size due to the influence on the diffusion rate and amount of FA in water-phase microdroplets. The honeycombed silica microspheres have obvious microscopic visible ultramacroporous cavities with the submicrometer cavity diameter as high as 85% porosity based on the rough overall volume of microsphere. N2 adsorption-desorption isotherms show that the honeycombed hierarchical porosity silica microspheres have a high surface area of 602 m2 g-1, a mesopore volume of 0.77 cm3/g, and a mesopore porosity of 99.6% based on the total pore volume of N2 adsorption-desorption. On the basis of the experiment results, a rational formation process of the honeycombed hierarchical porosity silica microspheres was deduced.

  • 171.
    Kalogiannis, Konstantinos G
    et al.
    Chemical Process and Energy Resources Institute (CPERI), Centre for Research and Technology Hellas (CERTH), 6th km Harilaou-Thermi Rd, 57001 Thessaloniki, Greece.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Aspden, James
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Lappas, Angelos A
    Chemical Process and Energy Resources Institute (CPERI), Centre for Research and Technology Hellas (CERTH), 6th km Harilaou-Thermi Rd, 57001 Thessaloniki, Greece.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Acid Assisted Organosolv Delignification of Beechwood and Pulp Conversion towards High Concentrated Cellulosic Ethanol via High Gravity Enzymatic Hydrolysis and Fermentation2018Inngår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 23, nr 7, artikkel-id 1647Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Future biorefineries will focus on converting low value waste streams to chemical products that are derived from petroleum or refined sugars. Feedstock pretreatment in a simple, cost effective, agnostic manner is a major challenge.

    Methods: In this work, beechwood sawdust was delignified via an organosolv process, assisted by homogeneous inorganic acid catalysis. Mixtures of water and several organic solvents were evaluated for their performance. Specifically, ethanol (EtOH), acetone (AC), and methyl- isobutyl- ketone (MIBK) were tested with or without the use of homogeneous acid catalysis employing sulfuric, phosphoric, and oxalic acids under relatively mild temperature of 175 °C for one hour.

    Results: Delignification degrees (DD) higher than 90% were achieved, where both AC and EtOH proved to be suitable solvents for this process. Both oxalic and especially phosphoric acid proved to be good alternative catalysts for replacing sulfuric acid. High gravity simultaneous saccharification and fermentation with an enzyme loading of 8.4 mg/gsolids at 20 wt.% initial solids content reached an ethanol yield of 8.0 w/v%.

    Conclusions: Efficient delignification combining common volatile solvents and mild acid catalysis allowed for the production of ethanol at high concentration in an efficient manner

  • 172.
    Kalogiannis, Konstantinos G.
    et al.
    Chemical Process and Energy Resources Institute (CPERI), Centre for Research and Technology Hellas (CERTH), Thessaloniki, Greece.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Lappas, Angelos A.
    Chemical Process and Energy Resources Institute (CPERI), Centre for Research and Technology Hellas (CERTH), Thessaloniki, Greece.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Aromatics from Beechwood Organosolv Lignin through Thermal and Catalytic Pyrolysis2019Inngår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, nr 9, artikkel-id 1606Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biomass fractionation, as an alternative to biomass pretreatment, has gained increasing research attention over the past few years as it provides separate streams of cellulose, hemicellulose, and lignin. These streams can be used separately and can provide a solution for improving the economics of emerging biorefinery technologies. The sugar streams are commonly used in microbial conversions, whereas during recent years lignin has been recognized as a valuable compound as it is the only renewable and abundant source of aromatic chemicals. Successfully converting lignin into valuable chemicals and products is key in achieving both environmental and economic sustainability of future biorefineries. In this work, lignin retrieved from beechwood sawdust delignification pretreatment via an organosolv process was depolymerized with thermal and catalytic pyrolysis. ZSM-5 commercial catalyst was used in situ to upgrade the lignin bio-oil vapors. Lignins retrieved from different modes of organosolv pretreatment were tested in order to evaluate the effect that upstream pretreatment has on the lignin fraction. Both thermal and catalytic pyrolysis yielded oils rich in phenols and aromatic hydrocarbons. Use of ZSM-5 catalyst assisted in overall deoxygenation of the bio-oils and enhanced aromatic hydrocarbons production. The oxygen content of the bio-oils was reduced at the expense of their yield. Organosolv lignins were successfully depolymerized towards phenols and aromatic hydrocarbons via thermal and catalytic pyrolysis. Hence, lignin pyrolysis can be an effective manner for lignin upgrading towards high added value products

  • 173.
    Kanelli, Maria
    et al.
    Laboratory of Polymer Technology, School of Chemical Engineering, National Technical University of Athens.
    Douka, Aliki
    Laboratory of Polymer Technology, School of Chemical Engineering, National Technical University of Athens.
    Vouyiouka, Stamatina
    Laboratory of Polymer Technology, School of Chemical Engineering, National Technical University of Athens.
    Papaspyrides, Constatine D.
    Laboratory of Polymer Technology, School of Chemical Engineering, National Technical University of Athens.
    Topakas, Evangelos
    BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Papaspyridi, Lefki-Maria
    National Technical University of Athens.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Production of biodegradable polyesters via enzymatic polymerization and solid state finishing2014Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, nr 19, artikkel-id 40820Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthesis of aliphatic polyesters (PEs) derived from diols (1,4-butanediol and 1,8-octanediol) and diacids or their derivatives (diethyl succinate, sebacic acid, 1,12-dodecanedioic acid, and 1,14-tetradecanedioic acid) was achieved in order to produce poly(butylene succinate) (PE 4.4), poly(octylene sebacate) (PE 8.10), poly(octylene dodecanate) (PE 8.12), and poly(octylene tetradecanate) (PE 8.14). The herein suggested procedure involved two stages, both sustainable and in accordance with the principles of "green" polymerization. The first comprised an enzymatic prepolymerization under vacuum, in the presence of diphenylether as solvent using Candida antarctica lipase B as biocatalyst, whereas a low-temperature postpolymerization step [solid state polymerization (SSP)] followed in order to upgrade the PEs quality. In the enzymatically synthesized prepolymers, the range of number-average molecular weight attained was from 3700 to 8000 g/mol with yields reaching even 97%. Subsequently, SSP of PE 4.4 and 8.12 took place under vacuum or flowing nitrogen and lasted 10-48 h, at temperatures close to the prepolymer melting point (Tm -  TSSP varied between 4°C and 14°C). The solid state finishing led to increase in the molecular weight depending on the prepolymer type, and it also contributed to improvement of the physical characteristics and the thermal properties of the enzymatically synthesized PEs

  • 174.
    Kanelli, Maria
    et al.
    IndBioCat Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Mandic, Mina
    Institute of Molecular Genetics and Genetic Engineering, University of Belgrade.
    Kalakona, Margarita
    IndBioCat Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athen.
    Vasilakos, Sozon
    Materials Industrial Research and Technology Center S.A., Athens.
    Kekos, Dimitris
    IndBioCat Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Nikodinovic-Runic, Jasmina
    Institute of Molecular Genetics and Genetic Engineering, University of Belgrade.
    Topakas, Evangelos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. IndBioCat Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Microbial Production of Violacein and Process Optimization for Dyeing Polyamide Fabrics With Acquired Antimicrobial Properties2018Inngår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 9, artikkel-id 1495Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study, crude bacterial extract containing violacein is investigated for the preparation of antimicrobial polyamide fabrics. The optimal culture conditions of Janthinobacterium lividum (JL) for maximum biomass and violacein production were found to be 25°C, pH 7.0, while the addition of ampicillin of 0.2 mg mL-1 in the small scale increased violacein production 1.3-fold. In scale-up trials, the addition of 1% (v/v) glycerol in a fed-batch bioreactor, resulted in fivefold extracted crude violacein increase with final concentration of 1.828 g L-1. Polyamide 6.6 fabrics were dyed following three different processes; through simultaneous fermentation and dyeing (SFD), by incubating the fabric in the sonicated bacterial culture after fermentation and by using cell-free extract containing violacein. Maximum color change (ΔE) and color strength (K/S) obtained for SFD fabrics were 74.81 and 22.01, respectively, while no alteration of fastness and staining of dye at acid and alkaline perspiration or at water was indicated. The dyed fabrics presented significant antifungal activity against Candida albicans, C. parapsilosis, and C. krusei, as well as antibacterial properties against Escherichia coli, Staphylococcus aureus, and the S. aureus MRSA. We have shown that J. lividum cultures can be successfully used for violacein production and for simultaneous dying of fabrics resulting in dyed fabrics with antimicrobial properties without utilization of organic solvents.

  • 175.
    Kanelli, Maria
    et al.
    National Technical University of Athens, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Vasilakos, Sozon
    MIRTEC, Materials Industrial Research & Technology Center S.A.
    Ladas, Spyridon
    Surface Science Laboratory, Department of Chemical Engineering, University of Patras.
    Symianikis, Emmanouil
    Surface Science Laboratory, Department of Chemical Engineering, University of Patras.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Topakas, Evangelos
    National Technical University of Athens, School of Chemical Engineering, National Technical University of Athens, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Surface modification of polyamide 6.6 fibers by enzymatic hydrolysis2016Inngår i: Process Biochemistry, ISSN 1359-5113, E-ISSN 1873-3298, Vol. 59 A, s. 97-103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Synthetic fibers are used extensively in textile industry, however, their high hydrophobicity is a drawback that needs to be considered. The decrease of hydrophobicity can be achieved via a ‘green” root using enzymes as biocatalysts. In this study, the enzymatic surface modification of polyamide (PA) 6.6 fabric was studied with the use of the commercial protease Alcalase 2.4 L at optimal conditions. The modified fabrics were studied via dyeing parameters K/S and ΔΕ values. For treatment at 40–60 °C and pH 8 ΔE was found to be approximately 14 and K/S was 1.24-fold increased. Additionally, the enzymatic surface modification of PA textile was justified using different spectroscopy techniques, such as FTIR-ATR and XPS. FTIR-ATR indicated alterations of Cdouble bond; length as m-dashO and N-H band intensities, while via XPS, there proved to be differences in relative intensities of carbon component peaks. Finally, thermogravimetric and mechanical tests were also conducted to prove the non-degradation of the properties of the bulk material. In conclusion, the investigated enzymatic process increased the hydrophilicity with 2.7-fold increased water absorbency and 1.24-fold enhanced color strength of PA textiles, while maintaining the thermal and mechanical properties of the bulk synthetic material.

  • 176.
    Kanelli, Maria
    et al.
    National Technical University of Athens.
    Vasilakos, Sozon
    MIRTEC, Materials Industrial Research & Technology Center S.A.
    Nikolaivits, Efstratios
    Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Ladas, Spyridon
    Surface Science Laboratory, Department of Chemical Engineering, University of Patras.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Topakas, Evangelos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Surface modification of poly(ethylene terephthalate) (PET) fibers by a cutinase from Fusarium oxysporum2015Inngår i: Process Biochemistry, ISSN 1359-5113, E-ISSN 1873-3298, Vol. 50, nr 11, s. 1885-1892Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Synthetic polyester fabrics occupy a great part of the textile industry production satisfying variable ordinary needs. Nonetheless, their high hydrophobicity constitutes an important weakness that impedes process manufacture, as well as permeability and evaporation of sweat when used in clothing industry. The enzymatic treatment of these materials is a modern and eco-friendly procedure that aims at the increase of the hydrophilicity through superficial modification. In this study, the enzymatic surface hydrolysis of poly(ethylene terephthalate) (PET) fabric is succeeded using a recombinant cutinase from Fusarium oxysporum. The effect of various parameters is studied for the enzymatic modification of PET, such as temperature, pH, enzyme loading and reaction time. The optimal parameters are found to be 40 °C, pH 8, and 1.92 mg enzyme loading per gram of fabric. The controlled enzymatic hydrolysis of PET textile is further confirmed and characterized using various spectroscopic and analytical methods, including Fourier Transform Infrared (FT-IR) in the Attenuated Total Reflectance mode (ATR) and X-ray photoelectron spectroscopy (XPS). Tensile test and dyeability analyses were also employed achieving a K/S increase up to 150%, confirming the successful surface modification without degrading the quality of the starting material.

  • 177.
    Kanwal, Sehrish
    et al.
    Department of Chemistry, Quaid-i-Azam University, Islamabad, Pakistan.
    Ali, Naveed Zafar
    Federal Institute for Materials Research and Testing (BAM), Richard-Will, Berlin, Germany. National Center for Physics, Quaid-i-Azam University Campus, Islamabad, Pakistan.
    Hussain, Rizwan
    National Center for Physics, Quaid-i-Azam University Campus, Islamabad, Pakistan. Laboratory of Advance Materials & Processing (LAMP), University of Maryland, USA.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Akhter, Zareen
    Department of Chemistry, Quaid-i-Azam University, Islamabad, Pakistan.
    Poly-thiourea formaldehyde based anticorrosion marine coatings on Type 304 stainless steel2020Inngår i: Journal of Materials Research and Technology, ISSN 2238-7854Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study, hexamethylene diisocyanate (HMDI) encapsulated poly-thiourea formaldehyde (PTF) (10 wt%) coating was developed in an epoxy-polyamine matrix and their anticorrosion studies on Type SS304 stainless steel substrate have been conducted using electrochemistry techniques. The compact and hydrophobic shell wall of PTF proved to be a potent shell wall material for HMDI encapsulation. The effect of temperature and pH values was found to be decisive factor in the synthesis of microcapsules. The PTF microcapsules were synthesized in acidic condition with a pH value of 3. Over 90% of the core fraction is retained in water after 21 days immersion. However, core content decreased with increasing temperature. The capsules were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy(SEM), thermogravimetric analysis (TGA) and Electrochemical Impedance spectroscopy (EIS). Scanning electron microscopic analysis depicts the uniform morphology of coating with a particle size in the range of 1.08 μm–22.06 μm. The vibrational band at 2271 cm−1 attributed to NCO signal further endorses the successful encapsulation of HMDI into the PTF capsules. Electrochemical testing on steel specifies the appreciable anticorrosion performance of the synthesized poly thiourea formaldehyde (PTF) coating against artificial sea water.

  • 178.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Claudpierre, Simon
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Nanocellulose based functional membranes for water cleaning: Tailoring of mechanical properties, porosity and metal ion capture2016Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 514, s. 418-428Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multi-layered nanocellulose membranes were prepared using vacuum-filtration of cellulose nanofibers (CNF) suspensions followed by dip coating with cellulose nanocrystals having sulphate (CNCSL) or carboxyl surface groups (CNCBE). It was possible to tailor the specific surface area, pore structure, water flux and wet strength of the membranes based on drying conditions and acetone treatment. CNF coated with CNCBE showed the highest a tensile strength (95 MPa), which decreased in wet conditions (≈3.7 MPa) and with acetone (2.7 MPa) treatment. The water dried membranes showed pore sizes in nanofiltration range (74 Å) from liquid nitrogen adsorption/desorption data and the acetone treatment increased the average pore sizes to tight ultrafiltration range (194Å) with a concomitant increase (7000%) of the BET surface area. The water flux, also increased from zero to 25 Lm-2h-1 at a pressure differential of 0.45 MPa, for acetone treated ones. The membranes irrespective of the surface functionality showed exceptional capability (≈100%) to remove Ag+, Cu2+ and Fe3+ ions from mirror industry effluents. Surface adsorption followed by microprecipitation was considered as the possible mechanism of ion removal, which opens up a new generation of ultrafiltration membranes with high selectivity towards ions and low-pressure demands.

  • 179.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Nanoporous membranes with cellulose nanocrystals as functional entity in chitosan: removal of dyes from water2014Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 112, s. 668-676Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fully biobased composite membranes for water purification were fabricated with cellulose nanocrystals (CNCs) as functional entities in chitosan matrix via freeze-drying process followed by compacting. The chitosan (10 wt%) bound the CNCs in a stable and nanoporous membrane structure with thickness of 250-270 μm, which was further stabilized by cross-linking with gluteraldehyde vapors. Scanning electron microscopy (SEM) studies revealed well-individualized CNCs embedded in a matrix of chitosan. Brunauer, Emmett and Teller (BET) measurements showed that the membranes were nanoporous with pores in the range of 13-10 nm. In spite of the low water flux (64 L m-2 h-1), the membranes successfully removed 98%, 84% and 70% respectively of positively charged dyes like Victoria Blue 2B, Methyl Violet 2B and Rhodamine 6G, after a contact time of 24 h. The removal of dyes was expected to be driven by the electrostatic attraction between negatively charged CNCs and the positively charged dyes.

  • 180.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Kokol, Vanja
    University of Maribor, Institute for Engineering Materials and Design, Smetanova ul. 17, SI-2000 Maribor, Slovenia.
    Wei, Jiang
    Alfa Laval Nakskov A/S, Business Center Membranes, Stavangervej 10, DK-4900, Nakskov, Denmark.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    High-flux affinity membranes based on cellulose nanocomposites for removal of heavy metal ions from industrial effluents2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 25, s. 20644-20653Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fully biobased affinity membrane processing and its application in the removal of heavy metal ions from mirror industry effluents were successfully demonstrated; indicating the potential use of these membranes in point-of-use or point-of-entry water cleaning products that are cheap, environmentally friendly and efficient. Layered cellulose nanocomposite membranes were fabricated using cellulose microfiber sludge as a support layer and cellulose nanocrystals (CNCSL, CNCBE or PCNCSL) in a gelatin matrix as the functional layer. Scanning electron microscopy (SEM) studies revealed the bi-layered morphology of the membrane and well-individualized nanocelluloses in the functional layer. Bubble point measurements confirmed the membrane pore structure in the microfiltration range (5.0-6.1 μm), which provided very high water permeability (900-4000 L h-1 m-2) at <1.5 bars. A tensile strength of 16 MPa in dry conditions and a wet strength of 0.2 MPa, was considered sufficient for use of these membranes in spiral wound modules. Mirror industry effluent laden with metal ions (Ag+ and Cu2+/Fe3+/Fe2+) when treated with cellulose nanocomposite membranes, showed high ion removal capacity, being 100% for PCNCSL followed by CNCBE than CNCSL. The removal of metal ions was expected to be driven by interactions between negatively charged nanocellulose and the positively charged metal ions.

  • 181.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Cellulose nanocrystals based nanocompositemembranes for water purification: Process-Property correlation2015Konferansepaper (Annet vitenskapelig)
  • 182.
    Karim, Zoheb
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Fully biobased nanocomposite membranes: removal of heavy metals from polluted water2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Biobased nanoparticles viz cellulose nanocrystals (CNCs) and cellulose nanofiber (CNFs) isolated by mechanical process (grinding) were used to fabricate of fully biobased nanocomposite membranes. Biobased nanofibers were used as support layer via a very simple process of vacuum filtration was used for the fabrication of CNF support layer. In order to coat CNCs or CNCbio on the two sides to CNF layer, the membrane was dipped in a solution of cellulose nanocrystals. Scanning electron microscopy (SEM) confirmed the infusion of functional layer within supportive layer. Tensile strength was measured in dry as well as in wet conditions, illustrated mechanical performances compareble to commercially available membranes. To increase the flux, membranes were treated with acetone for 24 and 72 h. The drastic increase in the flux for acetone treated membranes confirmed the discontinuities of hydrogen . The membranes succefully removed two metal ions Ag+ and As3- from real wastewater, from mirror making and mining industries respectively, within Europe. Complete removal of Ag+ was reported after 24 h of incubation. The study concludes that, the developed membranes having good mechanical stability in wet conditions, high water flux and adsorption efficiency are potential candidates for heavy metal ion remediation of industrial effluents.

  • 183.
    Karimi, Somayeh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Korelskiy, Danil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mortazavi, Yadollah
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Khodadadi, Abbas Ali
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Sardari, Kaymar
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Esmaeili, Mohammad
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Antzutkin, Oleg
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Shah, Faiz Ullah
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    High flux acetate functionalized silica membranes based on in-situ co-condensation for CO2/N2 separation2016Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 520, s. 574-582Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Acetate-functionalized silica membranes were prepared via co-condensation. The molar ratio of functional groups in the silica matrix was varied in the range of 0–0.6, denoted by x. The presence of functional groups bonded to the silica network was revealed by FTIR and 29Si and 13C solid-state NMR analysis. The stability of the groups was studied by TG analysis. The membranes were evaluated for CO2/N2 mixture separation in a temperature range of 253–373 K using a feed pressure of 9 bar and a sweep gas kept at atmospheric pressure on the permeate side. The membranes were found to be CO2-selective at all the conditions studied. The highest observed selectivity was 16 for x=0.4, with a CO2 permeance of 5.12×10−7 mol s−1 m−2 Pa−1. For x=0.2, a permeance of as high as 20.74×10−7 mol s−1 m−2 Pa−1 with a CO2/N2 selectivity of 7.5 was obtained. This permeance is the highest reported for CO2/N2 separation using functionalized silica membranes. It is proposed that the separation mechanism between CO2 and N2 was the preferential adsorption of CO2, which inhibited adsorption and permeation of N2 through the silica pore network. Permporometry results revealed that as the loading of functional groups increased, the He permeance decreased. It was also indicated that the quantity of micropores in the functionalized membrane was higher than that in the parent silica membrane.

  • 184.
    Karimi, Somayeh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Korelskiy, Danil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Yu, Liang
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Khodadadi, Abbas Ali
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Mortazavi, Yadollah
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Esmaeili, Mohammad
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    A simple method for blocking defects in zeolite membranes2015Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 489, s. 270-274Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The abatement of defects in zeolite membranes is essential for achieving high selectivity. In the present work, a simple and effective method for blocking defects in ultra-thin (ca. 0.5 μm) MFI zeolite membranes has been developed. The method is based on deposition of an ultra-thin (∼15 nm) layer of amorphous silica on the top surface of the membrane. Permporometry data indicated that the amount of defects, especially defects larger than 4 nm, in the membranes was significantly reduced after the modification. In mixture separation experiments, the CO2/H2 separation factor increased dramatically after blocking the defects in a defective membrane that was selected for the experiments. For instance, at 263 K and 9 bar feed pressure, the CO2/H2 separation factor increased from 8.5 to 36 after modification of the membrane, whereas the CO2 flux only decreased by ca. 40%.

  • 185.
    Karimi, Somayeh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran, Tehran, Iran.
    Mortazavi, Yadollah
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran, Tehran, Iran.
    Khodadadi, Abbas Ali
    Catalysis and Nanostructured Materials Research Laboratory, College of Engineering, School of Chemical Engineering, University of Tehran, Tehran, Iran.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Korelskiy, Danil
    Materials Technology and Chemistry, Alfa Laval Tumba AB, Tumba, Sweden.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Functionalization of silica membranes for CO2 separation2020Inngår i: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 235, artikkel-id 116207Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Five organic CO2-philic functional groups were incorporated in silica matrixes for preparation of functionalized silica membranes to explore the CO2 separation performance. Chemical groups including acetate, trifluoromethyl, methacrylate, urea and vinyl groups were anchored in the silica network using the co-condensation method.

    The information from 29Si solid-state NMR and FTIR analyses indicates the successful formation of a covalent bond between functional groups and the silica network. The thickness of the functionalized silica layers was measured by SEM and the thermal stability of the organic groups was determined by thermogravimetric analysis (TGA).

    The gas permeance and mixed gas selectivity of CO2/N2 was measured in the temperature range of 253–373 K with a feed pressure of 9 bar. A maximum selectivity of as high as 10 was observed for a trifluoromethyl functionalized silica membrane with a CO2 permeance of 5.5 × 10−7 mol s−1 m−2 Pa−1. Permporometry measurements indicated that the contribution of flow through micropores to the total flow for all the functionalized silica membranes varied between 62 and 82%. All membranes were CO2 selective.

     

  • 186.
    Karlkvist, Tommy
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Patra, Anuttam
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Bordes, Romain
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Holmberg, Krister
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Rao, Hanumantha
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Flotation selectivity of novel alkyl dicarboxylate reagents for calcite-fluorite separation2016Inngår i: Tenside Surfactants Detergents, ISSN 0932-3414, E-ISSN 2195-8564, Vol. 53, nr 6, s. 516-523Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of amino acid-based surfactants with a fixed alkyl chain length and with two carboxyl groups separated by a spacer of one, two or three carbon atoms have been synthesized and evaluated as potential collectors for flotation of calcite and fluorite. A monocarboxylate amino acid-based surfactant having the same length of the hydrocarbon tail was also included in the study. Experiments using a Hallimond flotation tube showed that although the flotation reagents solely differs in terms of spacer, their efficacy in terms of flotation recovery varied very much. Whereas on calcite at pH 10.5 only the monocarboxylate collector gave a high yield, on fluorite at the same pH both the monocarboxylate and the dicarboxylate collectors with one carbon between the carboxyl groups gave good results. On calcite at the natural pH the monocarboxylate collector was most efficient but the dicarboxylate collectors with a two- and a three-carbon spacer also gave a reasonable recovery. On fluorite at the natural pH the dicarboxylate collectors with a two- and a three-carbon spacer were most efficient. The potential and the flotation recovery of the mineral particles as afunction of added collector was assessed and the adsorption was also monitored by diffuse reflectance infra-red spectroscopy. Taken together, the results showed that small changes in the head group region of the collector can radically affect flotation recovery. This type of knowledge is important to understand flotation selectivity in a mixture of similar minerals.

  • 187.
    Karlkvist, Tommy
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Patra, Anuttam
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rao, Hanumantha
    Bordes, Romain
    Chalmers University of Technology, Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Holmberg, Krister
    Chalmers University of Technology, Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Fredriksson, Andreas
    LKAB.
    Molecular recognition in mineral flotation: Selectivity in apatite-calcite system2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The present investigation aims to develop and distinguish mineral specific reagents with two functional groups for use in flotation of calcium containing minerals. For this purpose, a series of dicarboxylate-based surfactants with varying length between the carboxylate groups (one, two or three methylene groups) were synthesized. As reference, a surfactant with the same alkyl chain length but with only one carboxylate group in the polar part was synthesized. The adsorption behavior of these new reagents on pure apatite and calcite mineral surfaces was studied using Hallimond tube flotation, FTIR and ζ potential measurements. The relation between the adsorption behavior of a given surfactant on a specific mineral surface and its molecular structure over a range of concentration and pH values, as well as the region of maximum recovery were established. It was found that one of the reagents, with a specific distance between the carboxylate groups, was much more selective for a particular mineral surface than the other homologues synthesized. This selective adsorption of a given surfactant to a particular mineral surface relative to other mineral surfaces as evidenced in flotation studies is substantiated by ζ potential and infra-red spectroscopy data.

  • 188.
    Karnaouri, Anthi C
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Antonopoulou, Io
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Topakas, Evangelos
    National Technical University of Athens.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Genomic insights into the fungal lignocellulolytic system of Myceliophthora thermophila2014Inngår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 5, artikkel-id 5.281Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    he microbial conversion of solid cellulosic biomass to liquid biofuels may provide a renewable energy source for transportation fuels. Cellulolytic fungi represent a promising group of organisms, as they have evolved complex systems for adaptation to their natural habitat. The filamentous fungus Myceliophthora thermophila constitutes an exceptionally powerful cellulolytic microorganism that synthesizes a complete set of enzymes necessary for the breakdown of plant cell wall. The genome of this fungus has been recently sequenced and annotated, allowing systematic examination and identification of enzymes required for the degradation of lignocellulosic biomass. The genomic analysis revealed the existence of an expanded enzymatic repertoire including numerous cellulases, hemicellulases and enzymes with auxiliary activities, covering the most of the recognized CAZy families. Most of them were predicted to possess a secretion signal and undergo through post translational glycosylation modifications. These data offer a better understanding of activities embedded in fungal lignocellulose decomposition mechanisms and suggest that M. thermophila could be made usable as an industrial production host for cellulolytic and hemicellulolytic enzymes

  • 189.
    Karnaouri, Anthi C.
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Antonopoulou, Io
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Zerva, Anastasia
    Biotechnology Laboratory, Department of Synthesis and Development of Industrial Processes, School of Chemical Engineering, National Technical University of Athens, Athens, Greece.
    Dimarogona, Maria
    Section of Process and Environmental Engineering, Department of Chemical Engineering, University of Patras, Patras, Greece.
    Topakas, Evangelos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Biotechnology Laboratory, Department of Synthesis and Development of Industrial Processes, School of Chemical Engineering, National Technical University of Athens, Athens, Greece.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Thermophilic enzyme systems for efficient conversion of lignocellulose to valuable products: Structural insights and future perspectives for esterases and oxidative catalysts2019Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 279, s. 362-372Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermophilic enzyme systems are of major importance nowadays in all industrial processes due to their great performance at elevated temperatures. In the present review, an overview of the current knowledge on the properties of thermophilic and thermotolerant carbohydrate esterases and oxidative enzymes with great thermostability is provided, with respect to their potential use in biotechnological applications. A special focus is given to the lytic polysaccharide monooxygenases that are able to oxidatively cleave lignocellulose through the use of oxygen or hydrogen peroxide as co-substrate and a reducing agent as electron donor. Structural characteristics of the enzymes, including active site conformation and surface properties are discussed and correlated with their substrate specificity and thermostability properties.

  • 190.
    Karnaouri, Anthi C
    et al.
    Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Evangelos, Topakas
    Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Cloning, expression, and characterization of a thermostable GH7 endoglucanase from Myceliophthora thermophila capable of high-consistency enzymatic liquefaction2014Inngår i: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 98, nr 1, s. 231-242Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An endoglucanase gene from the thermophilic fungus Myceliophthora thermophila, belonging to the glycoside hydrolase family 7, was functionally expressed in methylotrophic yeast Pichia pastoris. The putative endoglucanase from the genomic DNA was successfully cloned in P. pastoris X-33 and the recombinant enzyme was purified to its homogeneity (65 kDa) and subsequently characterized. Substrate specificity analysis revealed that the enzyme exhibits high activity on substrates containing β-1,4-glycosidic bonds such as carboxymethyl cellulose, barley β-glucan, and cello-oligosaccharides, as well as activity on xylan-containing substrates, including arabinoxylan and oat spelt xylan. MtEG7a was proved to liquefy rapidly and efficiently pretreated wheat straw, indicating its key role to the initial step of hydrolysis of high-solids lignocellulose substrates. High thermostability of the endoglucanase reflects potential commercial significance of the enzyme

  • 191.
    Karnaouri, Anthi C
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Department of Chemical Sciences and Technologies, Via della Ricerca Scientifica, University of Rome Tor Vergata.
    Lange, Heikko
    Department of Chemical Sciences and Technologies, Via della Ricerca Scientifica, University of Rome Tor Vergata.
    Crestini, Claudia
    Department of Chemical Sciences and Technologies, Via della Ricerca Scientifica, University of Rome Tor Vergata.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Chemoenzymatic Fractionation and Characterization of Pretreated Birch Outer Bark2016Inngår i: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 4, nr 10, s. 5289-5302Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, the application of different chemical and enzymatic treatment methods for the fractionation of the birch outer bark components was evaluated. More specifically, untreated and steam exploded, hydrothermally and organosolv treated bark samples were incubated with enzyme mixtures that consisted of cellulases, hemicellulases and esterases, and the effect of enzymes was analyzed with 31P NMR and {13C-1H} HSQC. The biocatalysts performed the cleavage of ester bonds resulting in reduction of methoxy and aliphatic groups in the remaining solid fraction, whereas the aromatic fraction remained intact. Moreover, the suberin and lignin fraction were isolated chemically and their properties were characterized by gas chromatography (GC-MS), 31P NMR, {13C-1H} HSQC and gel permeation chromatography (GPC). It was demonstrated that the lignin fraction was enriched in guaiacyl phenolics but still contained some associated aliphatic acids and carbohydrates, whereas the suberin fraction presented a polymodal pattern of structures with different molecular weight distributions. This work will help in getting a deeper fundamental knowledge of the bark structure, the intermolecular connection between lignin and suberin fractions, as well as the potential use of enzymes in order to degrade the recalcitrant bark structure toward its valorization.

  • 192.
    Karnaouri, Anthi C.
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Bühler, Saskja
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Muraleedharan, Madhu Nair
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Tailoring Celluclast (R) Cocktail's Performance towards the Production of Prebiotic Cello-Oligosaccharides from Waste Forest Biomass2019Inngår i: Catalysts, E-ISSN 2073-4344, Vol. 9, nr 11, artikkel-id 897Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main objective of this study focused on the sustainable production of cellobiose and other cellulose-derived oligosaccharides from non-edible sources, more specifically, from forest residues. For this purpose, a fine-tuning of the performance of the commercially available enzyme mixture Celluclast® was conducted towards the optimization of cellobiose production. By enzyme reaction engineering (pH, multi-stage hydrolysis with buffer exchange, addition of β-glucosidase inhibitor), a cellobiose-rich product with a high cellobiose to glucose ratio (37.4) was achieved by utilizing organosolv-pretreated birch biomass. In this way, controlled enzymatic hydrolysis combined with efficient downstream processing, including product recovery and purification through ultrafiltration and nanofiltration, can potentially support the sustainable production of food-grade oligosaccharides from forest biomass. The potential of the hydrolysis product to support the growth of two Lactobacilli probiotic strains as a sole carbon source was also demonstrated

  • 193.
    Karnaouri, Anthi C.
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Krikigianni, Eleni
    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.
    Valorization of waste forest biomass toward the production of cello-oligosaccharides with potential prebiotic activity by utilizing customized enzyme cocktails2019Inngår i: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 12, nr 1, artikkel-id 285Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background

    Production of value-added materials from lignocellulosic biomass residues is an emerging sector that has attracted much attention as it offers numerous benefits from an environmental and economical point of view. Non-digestible oligosaccharides represent a group of carbohydrates that are resistant to gastrointestinal digestion, and therefore, they are considered as potential prebiotic candidates. Such oligosaccharides can derive from the biomass cellulose fraction through a controlled enzymatic hydrolysis that eliminates the yield of monomers.

    Results

    In the present study, hydrolysis of organosolv-pretreated forest residues (birch and spruce) was tested in the presence of four cellulases (EG5, CBH7, CBH6, EG7) and one accessory enzyme (LPMO). The optimal enzyme combinations were comprised of 20% EG5, 43% CBH7, 22% TtLPMO, 10% PaCbh6a and 5% EG7 in the case of birch and 35% EG5, 45% CBH7, 10% TtLPMO, 10% PaCbh6a and 5% EG7 in the case of spruce, leading to 22.3% and 19.1 wt% cellulose conversion into cellobiose, respectively. Enzymatic hydrolysis was applied on scale-up reactions, and the produced oligosaccharides (consisted of > 90% cellobiose) were recovered and separated from glucose through nanofiltration at optimized temperature (50 °C) and pressure (10 bar) conditions, yielding a final product with cellobiose-to-glucose ratio of 21.1 (birch) and 20.2 (spruce). Cellobiose-rich hydrolysates were tested as fermentative substrates for different lactic acid bacteria. It was shown that they can efficiently stimulate the growth of two Lactobacilli strains.

    Conclusions

    Controlled enzymatic hydrolysis with processive cellulases, combined with product recovery and purification, as well as enzyme recycling can potentially support the sustainable production of food-grade oligosaccharides from forest biomass.

  • 194.
    Karnaouri, Anthi C
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Matsakas, Leonidas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Topakas, Evangelos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Department of Chemical Engineering, Biotechnology Laboratory, National Technical University of Athens.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Development of Thermophilic Tailor-Made Enzyme Mixtures for the Bioconversion of Agricultural and Forest Residues2016Inngår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 7, artikkel-id 177Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Even though the main components of all lignocellulosic feedstocks include cellulose, hemicellulose, as well as the protective lignin matrix, there are some differences in structure, such as in hardwoods and softwoods, which may influence the degradability of the materials. Under this view, various types of biomass might require a minimal set of enzymes that has to be tailor-made. Partially defined complex mixtures that are currently commercially used are not adapted to efficiently degrade different materials, so novel enzyme mixtures have to be customized. Development of these cocktails requires better knowledge about the specific activities involved, in order to optimize hydrolysis. The role of filamentous fungus Myceliophthora thermophila and its complete enzymatic repertoire for the bioconversion of complex carbohydrates has been widely proven. In this study, four core cellulases (MtCBH7, MtCBH6, MtEG5, and MtEG7), in the presence of other four “accessory” enzymes (mannanase, lytic polyssacharide monooxygenase MtGH61, xylanase, MtFae1a) and β-glucosidase MtBGL3, were tested as a nine-component cocktail against one model substrate (phosphoric acid swollen cellulose) and four hydrothermally pretreated natural substrates (wheat straw as an agricultural waste, birch, and spruce biomass, as forest residues). Synergistic interactions among different enzymes were determined using a suitable design of experiments methodology. The results suggest that for the hydrolysis of the pure substrate (PASC), high proportions of MtEG7 are needed for efficient yields. MtCBH7 and MtEG7 are enzymes of major importance during the hydrolysis of pretreated wheat straw, while MtCBH7 plays a crucial role in case of spruce. Cellobiohydrolases MtCBH6 and MtCBH7 act in combination and are key enzymes for the hydrolysis of the hardwood (birch). Optimum combinations were predicted from suitable statistical models which were able to further increase hydrolysis yields, suggesting that tailor-made enzyme mixtures targeted toward a particular residual biomass can help maximize hydrolysis yields. The present work demonstrates the change from “one cocktail for all” to “tailor-made cocktails” that are needed for the efficient saccharification of targeted feed stocks prior to the production of biobased products through the biorefinery concept.

  • 195.
    Karnaouri, Anthi C
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Muraleedharan, Madhu Nair
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Dimarogona, Maria
    Biotechnology Laboratory, Department of Synthesis and Development of Industrial Processes, School of Chemical Engineering, National Technical University of Athens.
    Topakas, Evangelos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Rova, Ulrika
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Sandgren, Mats
    Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Recombinant expression of thermostable processive MtEG5 endoglucanase and its synergism with MtLPMO from Myceliophthora thermophila during the hydrolysis of lignocellulosic substrates2017Inngår i: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 10, nr 1, artikkel-id 126Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

     Background

    Filamentous fungi are among the most powerful cellulolytic organisms in terrestrial ecosystems. To perform the degradation of lignocellulosic substrates, these microorganisms employ both hydrolytic and oxidative mechanisms that involve the secretion and synergism of a wide variety of enzymes. Interactions between these enzymes occur on the level of saccharification, i.e., the release of neutral and oxidized products, but sometimes also reflected in the substrate liquefaction. Although the synergism regarding the yield of neutral sugars has been extensively studied, further studies should focus on the oxidized sugars, as well as the effect of enzyme combinations on the viscosity properties of the substrates.

    Results

    In the present study, the heterologous expression of an endoglucanase (EG) and its combined activity together with a lytic polysaccharide monooxygenase (LPMO), both from the thermophilic fungus Myceliophthora thermophila, are described. The EG gene, belonging to the glycoside hydrolase family 5, was functionally expressed in the methylotrophic yeast Pichia pastoris. The produced MtEG5A (75 kDa) featured remarkable thermal stability and showed high specific activity on microcrystalline cellulose compared to CMC, which is indicative of its processivity properties. The enzyme was capable of releasing high amounts of cellobiose from wheat straw, birch, and spruce biomass. Addition of MtLPMO9 together with MtEG5A showed enhanced enzymatic hydrolysis yields against regenerated amorphous cellulose (PASC) by improving the release not only of the neutral but also of the oxidized sugars. Assessment of activity of MtEG5A on the reduction of viscosity of PASC and pretreated wheat straw using dynamic viscosity measurements revealed that the enzyme is able to perform liquefaction of the model substrate and the natural lignocellulosic material, while when added together with MtLPMO9, no further synergistic effect was observed.

    Conclusions

    The endoglucanase MtEG5A from the thermophilic fungus M. thermophila exhibited excellent properties that render it a suitable candidate for use in biotechnological applications. Its strong synergism with LPMO was reflected in sugars release, but not in substrate viscosity reduction. Based on the level of oxidative sugar formation, this is the first indication of synergy between LPMO and EG reported.

  • 196.
    Karnaouri, Anthi C
    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.
    Effect of Different Pretreatment Methods on Birch Outer Bark: New Biorefinery Routes2016Inngår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 21, nr 4, artikkel-id 427Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A comparative study among different pretreatment methods used for the fractionation of the birch outer bark components, including steam explosion, hydrothermal and organosolv treatments based on the use of ethanol/water media, is reported. The residual solid fractions have been characterized by ATR-FTIR, 13C-solid-state NMR and morphological alterations afterpretreatment were detected by scanning electron microscopy. The general chemical composition of the untreated and treated bark including determination of extractives, suberin, lignin and monosaccharides was also studied. Composition of the residual solid fraction and relative proportions of different components, as a function of the processing conditions, could be established. Organosolv treatment produces a suberin-rich solid fraction, while duringhydrothermal and steam explosion treatment cleavage of polysaccharide bonds occurs. This work will provide a deeper fundamental knowledge of the bark chemical composition, thus increasing the utilization efficiency of birch outer bark and may create possibilities to up-scale the fractionation processes.

  • 197.
    Karnaouri, Anthi C
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Topakas, Evangelos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. School of Chemical Engineering, National Technical University of Athens.
    Matsakas, Leonidas
    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.
    Fine-tuned enzymatic hydrolysis of organosolv pretreated forest materials for the efficient production of cellobiose2018Inngår i: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 6, artikkel-id 128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Non-digestible oligosaccharides (NDOs) are likely prebiotic candidates that have been related to the prevention of intestinal infections and other disorders for both humans and animals. Lignocellulosic biomass is the largest carbon source in the biosphere, therefore cello-oligosacharides (COS), especially cellobiose, are potentially the most widely available choice of NDOs. Production of COS and cellobiose with enzymes offers numerous benefits over acid-catalyzed processes, as it is milder, environmentally friendly and produces fewer by-products. Cellobiohydrolases (CBHs) and a class of endoglucanases (EGs), namely processive EGs, are key enzymes for the production of COS, as they have higher preference toward glycosidic bonds near the end of cellulose chains and are able to release soluble products. In this work, we describe the heterologous expression and characterization of two CBHs from the filamentous fungus Thermothelomyces thermophila, as well as their synergism with proccessive EGs for cellobiose release from organosolv pretreated spruce and birch. The properties, inhibition kinetics and substrate specific activities for each enzyme are described in detail. The results show that a combination of EGs belonging to Glycosyl hydrolase families 5, 6 and 9, with a CBHI and CBHII in appropriate proportions, can enhance the production of COS from forest materials, underpinning the potential of these biocatalysts in the production of NDOs.

  • 198.
    Karnaouri, Anthi
    et al.
    Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens.
    Chalima, Angelina
    Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens.
    Kalogiannis, Konstantinos G.
    Chemical Process and Energy Resources Institute (CPERI), CERTH.
    Varamogianni-Mamatsi, Despoina
    Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens.
    Lappas, Angelos
    Chemical Process and Energy Resources Institute (CPERI), CERTH.
    Topakas, Evangelos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens.
    Utilization of lignocellulosic biomass towards the production of omega-3 fatty acids by the heterotrophic marine microalga Crypthecodinium cohnii2020Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 303, artikkel-id 122899Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Omega-3 fatty acids have become a commodity of high nutritional and commercial value; intensive fishing and its environmental and social cost has led researchers to seeking alternative more sustainable ways of producing them. Heterotrophic microalgae such as Crypthecodinium cohnii, a marine dinoflagellate, have the ability to utilize various substrates and accumulate high amounts of docosahexaenoic acid (DHA). In this work, a mild oxidative organosolv pretreatment of beechwood pulps was employed that allowed up to 95% of lignin removal in a single stage, thus yielding a cellulose-rich solid fraction. The enzymatic hydrolysates were evaluated for their ability to support the growth and lipid accumulation of C. cohnii in batch and fed-batch cultures; the results verified the successful microalgae growth, while DHA reached up to 43.5% of the cell’s total lipids. The proposed bioprocess demonstrated the utilization of non-edible biomass towards high added value food supplements in a sustainable and efficient manner.

  • 199.
    Katsimpouras, Constantinos
    et al.
    Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Bénarouche, Anaïs
    INRA, Aix Marseille Université, UMR1163, Polytech Marseille, 13288, Marseille.
    Navarro, David
    INRA, Aix Marseille Université, UMR1163, Polytech Marseille, 13288, Marseille.
    Karpusas, Michael
    Physics Laboratory, Department of Biotechnology, Agricultural University of Athens.
    Dimarogona, Maria
    Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Berrin, Jean-Guy
    INRA, Aix Marseille Université, UMR1163, Polytech Marseille, 13288, Marseille.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Topakas, Evangelos
    Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Enzymatic synthesis of model substrates recognized by glucuronoyl esterases from Podospora anserina and Myceliophthora thermophila2014Inngår i: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 98, nr 12, s. 5507-5516, artikkel-id 10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Glucuronoyl esterases (GEs) are recently discovered enzymes that are suggested to cleave the ester bond between lignin alcohols and xylan-bound 4-O-methyl-d-glucuronic acid. Although their potential use for enhanced enzymatic biomass degradation and synthesis of valuable chemicals renders them attractive research targets for biotechnological applications, the difficulty to purify natural fractions of lignin-carbohydrate complexes hampers the characterization of fungal GEs. In this work, we report the synthesis of three aryl alkyl or alkenyl d-glucuronate esters using lipase B from Candida antarctica (CALB) and their use to determine the kinetic parameters of two GEs, StGE2 from the thermophilic fungus Myceliophthora thermophila (syn. Sporotrichum thermophile) and PaGE1 from the coprophilous fungus Podospora anserina. PaGE1 was functionally expressed in the methylotrophic yeast Pichia pastoris under the transcriptional control of the alcohol oxidase (AOX1) promoter and purified to its homogeneity (63 kDa). The three d-glucuronate esters contain an aromatic UV-absorbing phenol group that facilitates the quantification of their enzymatic hydrolysis by HPLC. Both enzymes were able to hydrolyze the synthetic esters with a pronounced preference towards the cinnamyl-d-glucuronate ester. The experimental results were corroborated by computational docking of the synthesized substrate analogues. We show that the nature of the alcohol portion of the hydrolyzed ester influences the catalytic efficiency of the two GEs.

  • 200.
    Katsimpouras, Constantinos
    et al.
    Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Antonopoulou, Io
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Topakas, Evangelos
    National Technical University of Athens, School of Chemical Engineering, National Technical University of Athens, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Role and Applications of Feruloyl Esterases in Biomass Bioconversion2016Inngår i: Microbial Enzymes in Bioconversions of Biomass / [ed] Vijai Kumar Gupta, Springer international , 2016, s. 79-123Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Ferulic acid esterases (FAEs) act synergistically with xylanases to hydrolyze the feruloylated decorations of the hemicellulosic fraction of cell wall material and therefore play a major role in the degradation of plant biomass. In this review, their role in plant biomass degradation, their production, classification, and structural determination are discussed. In addition, the production, physicochemical properties, and molecular biology of the different type of FAEs are presented, giving emphasis in their potential applications utilizing their hydrolytic and synthetic activity. A detailed map of the reaction systems used to date is demonstrated, underpinning the potential of these enzymes as biosynthetic tools in the synthesis of bioactive compounds for use in food and cosmeceutical industries.

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