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  • 1.
    Abbas, Ghulam
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Johansson, Gustav
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Alay-e-Abbas, Syed Muhammad
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Computational Materials Modeling Laboratory, Department of Physics, Government College University, Faisalabad 38040, Pakistan.
    Shi, Yijun
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, J. Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Quasi Three-Dimensional Tetragonal SiC Polymorphs as Efficient Anodes for Sodium-Ion Batteries2023In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 6, no 17, p. 8976-8988Article in journal (Refereed)
    Abstract [en]

    In the present work, we investigate, for the first time, quasi 3D porous tetragonal silicon–carbon polymorphs t(SiC)12 and t(SiC)20 on the basis of first-principles density functional theory calculations. The structural design of these q3-t(SiC)12 and q3-t(SiC)20 polymorphs follows an intuitive rational approach based on armchair nanotubes of a tetragonal SiC monolayer where C–C and Si–Si bonds are arranged in a paired configuration for retaining a 1:1 ratio of the two elements. Our calculations uncover that q3-t(SiC)12 and q3-t(SiC)20 polymorphs are thermally, dynamically, and mechanically stable with this lattice framework. The results demonstrate that the smaller polymorph q3-t(SiC)12 shows a small band gap (∼0.59 eV), while the larger polymorph of q3-t(SiC)20 displays a Dirac nodal line semimetal. Moreover, the 1D channels are favorable for accommodating Na ions with excellent (>300 mAh g–1) reversible theoretical capacities. Thus confirming potential suitability of the two porous polymorphs with an appropriate average voltage and vanishingly small volume change (<6%) as anodes for Na-ion batteries.

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  • 2.
    Aguilar-Mamani, Wilson
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Crystallization of NBA-ZSM-5 from kaolin2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

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

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

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

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

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

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

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  • 3.
    Ahmed, Hamzah
    et al.
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Shimpi, Manishkumar R.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Velaga, Sitaram P.
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol2017In: Drug Development and Industrial Pharmacy, ISSN 0363-9045, E-ISSN 1520-5762, Vol. 43, no 1, p. 89-97Article in journal (Refereed)
    Abstract [en]

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

  • 4.
    Ahmed, Mukhtiar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Fluorine-Free Ionic Liquids and Electrolytes: From Synthesis to Energy Storage Applications2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

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

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

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  • 5.
    Ahmed, Mukhtiar
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Bhowmick, Sourav
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Filippov, Andrei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Johansson, Patrik
    Materials Physics, Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ionic Liquids and Electrolytes with Flexible Aromatic Anions2023In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 29, no 41, article id e202301000Article in journal (Refereed)
    Abstract [en]

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

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  • 6.
    Ahmed, Mukhtiar
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Rao, Soniya S.
    Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Filippov, Andrei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Johansson, Patrik
    Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Aromatic Heterocyclic Anion Based Ionic Liquids and Electrolytes2023In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 25, no 4, p. 3502-3512Article in journal (Refereed)
    Abstract [en]

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

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  • 7.
    Ahmed, Naeem
    et al.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia.
    Siow, Kim S.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia.
    Wee, M. F. Mohd Razip
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, 43600, Bangi, Selangor, Malaysia.
    Patra, Anuttam
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    A study to examine the ageing behaviour of cold plasma-treated agricultural seeds2023In: Scientific Reports, E-ISSN 2045-2322, Vol. 13, article id 1675Article in journal (Refereed)
    Abstract [en]

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

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  • 8.
    Ahmed, Naeem
    et al.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia.
    Siow, Kim S.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia.
    Wee, Mohd Farhanulhakim Mohd Razip
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia.
    Ho, Wai Kuan
    Crops for Future, Jln Broga, Semenyih 43500, Selangor, Malaysia.
    Patra, Anuttam
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    The Hydrophilization and Subsequent Hydrophobic Recovery Mechanism of Cold Plasma (CP) Treated Bambara Groundnuts2022In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 1055, p. 161-169Article in journal (Refereed)
    Abstract [en]

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

  • 9.
    Akbar, Kamran
    et al.
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, 30172 Italy.
    Moretti, Elisa
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, 30172 Italy.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, 30172 Italy.
    Carbon Dots for Photocatalytic Degradation of Aqueous Pollutants: Recent Advancements2021In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 9, no 17, article id 2100532Article, review/survey (Refereed)
    Abstract [en]

    The immense progress of humanity on the technological, domestic, and industrial fronts comes at the cost of polluting the planet. Aquatic pollution is particularly dangerous since all life forms are directly linked to it. Each year tons of industrial and domestic pollutants make their way into aqueous systems. Efficient removal/degradation of these pollutants is of prime importance for the sustainable future. Among many technologies, photodegradation is an emerging and promising method for the successful removal of aqueous pollutants since it is powered by abundant solar light. The last decade had shown that carbon dots are among the most promising materials that can be utilized as an efficient tool to derive various solar-driven chemical reactions. Carbon dots possess unique photophysical and chemical properties such as light-harvesting over a broad-spectrum region, upconversion photoluminescence, photosensitizers, chemical inertness, and bivalent redox character, etc. The ease of synthesis of carbon dots at low cost also contributes hugely to their utilizations as an efficient photocatalyst for the degradation of aqueous pollutants. This review summarizes the recent progress made in the field of photodegradation of aqueous pollutants with the aid of carbon dots and their hybrids, highlighting the critical role carbon dots can play in the field. 

  • 10.
    Alay-e-Abbas, Syed Muhammad
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Computational Materials Modeling Laboratory, Department of Physics, Government College University, Faisalabad, 38040, Pakistan.
    Abbas, Ghulam
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Zulfiqar, Waqas
    Computational Materials Modeling Laboratory, Department of Physics, Government College University, Faisalabad, 38040, Pakistan; Department of Energy Conversion and Storage, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark.
    Sajjad, Muhammad
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Physics, Khalifa University of Science and Technology, Abu Dhabi, 127788, United Arab Emirates.
    Singh, Nirpendra
    Department of Physics, Khalifa University of Science and Technology, Abu Dhabi, 127788, United Arab Emirates; Center for Catalysis and Separation (CeCaS), Khalifa University of Science and Technology, Abu Dhabi, 127788, United Arab Emirates.
    Larsson, J. Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Structure inversion asymmetry enhanced electronic structure and electrical transport in 2D A3SnO (A = Ca, Sr, and Ba) anti-perovskite monolayers2023In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 16, no 1, p. 1779-1791Article in journal (Refereed)
    Abstract [en]

    Anti-perovskites A3SnO (A = Ca, Sr, and Ba) are an important class of materials due to the emergence of Dirac cones and tiny mass gaps in their band structures originating from an intricate interplay of crystal symmetry, spin-orbit coupling, and band overlap. This provides an exciting playground for modulating their electronic properties in the two-dimensional (2D) limit. Herein, we employ first-principles density functional theory (DFT) calculations by combining dispersion-corrected SCAN + rVV10 and mBJ functionals for a comprehensive side-by-side comparison of the structural, thermodynamic, dynamical, mechanical, electronic, and thermoelectric properties of bulk and monolayer (one unit cell thick) A3SnO anti-perovskites. Our results show that 2D monolayers derived from bulk A3SnO anti-perovskites are structurally and energetically stable. Moreover, Rashba-type splitting in the electronic structure of Ca3SnO and Sr3SnO monolayers is observed owing to strong spin-orbit coupling and inversion asymmetry. On the other hand, monolayer Ba3SnO exhibits Dirac cone at the high-symmetry Γ point due to the domination of band overlap. Based on the predicted electronic transport properties, it is shown that inversion asymmetry plays an essential character such that the monolayers Ca3SnO and Sr3SnO outperform thermoelectric performance of their bulk counterparts.

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  • 11.
    Alberoni, Chiara
    et al.
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, Italy.
    Barroso-Martín, Isabel
    Departamento de Química Inorgánica, Cristalografía y Mineralogía (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain.
    Infantes-Molina, Antonia
    Departamento de Química Inorgánica, Cristalografía y Mineralogía (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain.
    Rodríguez-Castellón, Enrique
    Departamento de Química Inorgánica, Cristalografía y Mineralogía (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain.
    Talon, Aldo
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, Italy.
    Zhao, Haiguang
    Qingdao University – College of Physics & State Key Laboratory of Bio-Fibers and Eco-Textiles, 308 Ningxia Road, Qingdao 266071, P. R. China.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, Italy.
    Moretti, Elisa
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, Italy.
    Ceria doping boosts methylene blue photodegradation in titania nanostructures2021In: Materials Chemistry Frontiers, E-ISSN 2052-1537, Vol. 5, no 11, p. 4138-4152Article in journal (Refereed)
    Abstract [en]

    Ceria-doped titania photocatalysts (ceria loading 0.25–5.0 wt%) were synthesized by hydrothermal methods for water remediation. Nanotubes (CeTNTx) and nanoparticles (CeTNPx) were obtained. Ceria doping was applied to tune the electronic properties of nanostructured titania, boosting its photocatalytic activity. CeTNT nanostructures contained anatase as the only titania phase, whereas the CeTNP series consisted of both anatase and rutile polymorphs. The Ce addition induced a decrease in the energy gap, allowing enhancement of visible light harvesting. The photodegradation of methylene blue, MB, in aqueous solution was chosen to study the influence of the morphology and the ceria loading on the photocatalytic response, under UV and solar light. Both CeO2–TiO2 nanoparticles and nanotubes were found to be very active under UV light. The highest MB degradation rates were obtained for the 0.25 wt% CeO2 doping, for both nanotubes and nanoparticles (0.123 and 0.146 min−1, respectively), able to photodegrade completely the dye after 120 min. The two samples are stable after a 3-cycle reusability test. The photo-response under simulated solar light confirmed that doping titania with ceria allows harvesting visible light absorption, enhancing its photoactivity. A maximum efficiency of 85% under simulated sunlight at a degradation rate of 0.054 min−1 was obtained. Transient photoluminescence confirmed that MB acts as a charge scavenger for the composite system. These results pointed out ceria-doped titania nanostructures as a promising class of photocatalysts for the degradation of dyes and other hazardous organic compounds in wastewater.

  • 12.
    Ali, Asad
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Laaksonen, Aatto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden; Center of Advanced Research in Bionanoconjugates and Biopolymers, ‘‘Petru Poni” Institute of Macromolecular Chemistry, Iasi 700469, Romania; State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Huang, Guo
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hussain, Shahid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Luo, Shuiping
    College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China.
    Shen, Pei Kang
    School of Resources, Environment and Materials, State Key Laboratory of Processing for Non-ferrous Metal and Featured Materials, Guangxi University, Nanning, 530004, PR China.
    Zhu, Jinliang
    School of Resources, Environment and Materials, State Key Laboratory of Processing for Non-ferrous Metal and Featured Materials, Guangxi University, Nanning, 530004, PR China.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Emerging strategies and developments in oxygen reduction reaction using high-performance Platinum-based electrocatalysts2023In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000Article, review/survey (Refereed)
  • 13.
    Ali, Asad
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. School of Resources, Environment and Materials, State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Nanning 530004 Guangxi, P. R. China, Guangxi University, Nanning 530004, PR China; School of Chemistry & Chemical Engineering, Guangxi University, Nanning 530004, PR China.
    Liang, Fengxing
    School of Resources, Environment and Materials, State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Nanning 530004 Guangxi, P. R. China, Guangxi University, Nanning 530004, PR China.
    Feng, Huiyan
    School of Resources, Environment and Materials, State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Nanning 530004 Guangxi, P. R. China, Guangxi University, Nanning 530004, PR China; School of Chemistry & Chemical Engineering, Guangxi University, Nanning 530004, PR China.
    Tang, Mei
    School of Resources, Environment and Materials, State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Nanning 530004 Guangxi, P. R. China, Guangxi University, Nanning 530004, PR China.
    Jalil Shah, Syed
    School of Chemistry & Chemical Engineering, Guangxi University, Nanning 530004, PR China.
    Ahmad, Fawad
    Department of Chemistry, University of Wah, Quaid Avenue, Wah Cantt, (47010), Punjab, Pakistan.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Kang Shen, Pei
    School of Resources, Environment and Materials, State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Nanning 530004 Guangxi, P. R. China, Guangxi University, Nanning 530004, PR China.
    Zhu, Jinliang
    School of Resources, Environment and Materials, State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Nanning 530004 Guangxi, P. R. China, Guangxi University, Nanning 530004, PR China.
    Gram-scale production of in-situ generated iron carbide nanoparticles encapsulated via nitrogen and phosphorous co-doped bamboo-like carbon nanotubes for oxygen evolution reaction2023In: Materials Science for Energy Technologies, E-ISSN 2589-2991, Vol. 6, p. 301-309Article in journal (Refereed)
    Abstract [en]

    Optimizing electrocatalytic activity and recognizing the most reactive sites for oxygen evolution reaction (OER) electrocatalysts are valuable to the order of renewable power. In this research article, we explored an innovative in-situ annealing technique for constructing iron carbide nanoparticles (Fe3C NPs) encapsulated via nitrogen and phosphorous doped bamboo-shape carbon nanotubes (NP-CNTs) for OER. Interestingly, the constructed Fe3C NPs@NP-CNT-800 composite exhibited remarkable electrochemical operation and offered a stable current density of 10 mA/cm2 at a lower overpotential (280 mV) in an alkaline solution. Furthermore, an innovative Fe3C NPs@N,P-CNT-800 hybrid surpassed the standard RuO2 electrocatalyst in terms of OER performance and showed negligible degradation in chronoamperometric (21 h) and chronopotentiometry (3000 cycles) analyses. The remarkable performance and stability are ascribed to the Fe3C NPs, novel tubular bamboo-like morphology of its carbon materials, and heteroatom doping, which contribute to the electrochemical interfaces, large surface area, active catalytic sites, and rapid charge transfer kinetics.

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  • 14.
    Ali, Salamat
    et al.
    School of Materials and Energy, Lanzhou University, Lanzhou 730000, China.
    Ahmad, Awais
    Department of Chemistry, The University of Lahore, Lahore, 54590, Pakistan; Departamento de Química Orgánica, Universidad de Córdoba, Campus Universitario de Rabanales, Edificio Marie Curie (C3), E-14014 Córdoba, Spain.
    Hussain, Iftikhar
    Department of Mechanical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong.
    Shah, Syed Shoaib Ahmad
    Department of Chemistry, School of Natural Sciences, National University of Sciences and Technology, Islamabad 44000, Pakistan.
    Ali, Shafqat
    Department of Physics, Shah Abdul Latif University Khairpur, Khairpur, Sindh, 66202, Pakistan.
    Ali, Asad
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Javed, Muhammad Sufyan
    Department of Chemistry, The University of Lahore, Lahore, 54590, Pakistan; School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China.
    Experimental and Theoretical Aspects of MXenes-Based Energy Storage and Energy Conversion Devices2023In: Journal of Chemistry and Environment, E-ISSN 2959-0132, Vol. 2, no 2, p. 54-81Article, review/survey (Refereed)
    Abstract [en]

    Transition metal carbides, nitrides, and carbonitrides (MXenes) have become an appealing framework for developing various energy applications. MXenes with van der Waals (vdW) interactions are facile, highly efficient, affordable, and self-assembled features that improve energy density. MXenes exhibit large surface area, high electric conductivity, and excellent electrochemical characteristics for various energy applications. This review summarizes and emphasizes the current developments in MXene with improved performance for energy storage or conversion devices, including supercapacitors (SCs), various types of rechargeable batteries (RBs), solar cells, and fuel cells. We discuss the crystal structures of MXenes properties of MXenes and briefly discuss them for different types of energy applications. Finally, the critical outlook and perspective for the MXene progress for applications in energy applications are also described.

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  • 15.
    Al-Jayyousi, Hiba
    et al.
    Department of Mechanical Engineering, Khalifa University of Science and Technology, Abu Dhabi 127788, United Arab Emirates.
    Eswaran, Mathan Kumar
    SRM Research Institute, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India.
    Ray, Avijeet
    Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, India.
    Sajjad, Muhammad
    Department of Physics, Khalifa University of Science and Technology, Abu Dhabi 127788, United Arab Emirates.
    Larsson, J. Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Singh, Nirpendra
    Department of Physics, Khalifa University of Science and Technology, Abu Dhabi 127788, United Arab Emirates; Center for Catalysis and Separations, Khalifa University of Science and Technology, Abu Dhabi 127788, United Arab Emirates.
    Exploring the Superior Anchoring Performance of the Two-Dimensional Nanosheets B2C4P2 and B3C2P3 for Lithium-Sulfur Batteries2022In: ACS Omega, E-ISSN 2470-1343, Vol. 7, no 43, p. 38543-38549Article in journal (Refereed)
    Abstract [en]

    Potential anchoring materials in lithium–sulfur batteries help overcome the shuttle effect and achieve long-term cycling stability and high-rate efficiency. The present study investigates the two-dimensional nanosheets B2C4P2 and B3C2P3 by employing density functional theory calculations for their promise as anchoring materials. The nanosheets B2C4P2 and B3C2P3 bind polysulfides with adsorption energies in the range from −2.22 to −0.75 and −2.43 to −0.74 eV, respectively. A significant charge transfer occurs from the polysulfides, varying from −0.74 to −0.02e and −0.55 to −0.02e for B2C4P2 and B3C2P3, respectively. Upon anchoring the polysulfides, the band gap of B3C2P3 reduces, leading to enhanced electrical conductivity of the sulfur cathode. Finally, the calculated barrier energies of B2C4P2 and B3C2P3 for Li2S indicate fast diffusion of Li when recharged. These enthralling characteristics propose that the nanosheets B2C4P2 and B3C2P3 could reduce the shuttle effect in Li–S batteries and significantly improve their cycle performance, suggesting their promise as anchoring materials.

  • 16.
    Altaee, Mohammed J.
    et al.
    Environmental Research and Studies Centre, University of Babylon, Hilla, Iraq.
    Altayee, Sarmed A. S.
    Department of Chemical Engineering, College of Engineering, University of Babylon, Hilla 51001, Iraq.
    Kadhim, Majid M. A.
    Department of Civil Engineering, College of Engineering, University of Babylon, Hilla 51001, Iraq.
    Jawdhari, Akram
    Department of Civil Engineering, Queen’s University, Kingston, Canada.
    Majdi, Ali
    Building and Construction Techniques Engineering, Al-Mustaqbal University College, 51001, Babylon, Iraq.
    Chabuk, Ali
    Department of Environment Engineering, College of Engineering, University of Babylon, Hilla 51001, Iraq.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. Department of Civil Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå 97187, Sweden.
    Evaluation of Existing Bond-Slip Relations for CFRP-Steel Joints and New Model for Linear and Nonlinear Adhesives2022In: Advances in Civil Engineering / Hindawi, ISSN 1687-8086, E-ISSN 1687-8094, Vol. 2022, article id 3673438Article in journal (Refereed)
    Abstract [en]

    Existing bond-slip (τ-s) relations for fibre-reinforced polymer (FRP)-steel joints employ different shapes and mathematical expressions, inferring that their predictions of failure load and mode, and other interface properties, might be inconsistent or inaccurate. In this study, predictions of four widely used τ-s relations are evaluated using a large experimental database of 78 double-lap FRP-steel specimens. To facilitate the evaluation process, a robust finite element (FE) model is developed for each test, implementing data from either of the existing τ-s relations to define the FRP-steel interface. Comparisons between test and FE results indicated that the existing τ-s models were unable of predicting the ultimate load (Pu) and effective bond length (Leff) of FRP-steel joints, or the relation between Pu and bond length and that between Leff and FRP modulus (Ef). A new τ-s model is developed based on an inverse FE simulation, comparison with experimental results, and regression analysis. It considers the effects of Ef, the type of FRP reinforcement (sheet or plate), and applies to both linear and nonlinear adhesives. The model predictions were validated by comparing with results from small bond tests and large FRP-strengthened steel beams tested under bending, yielding excellent results for Pu, failure mode, and all other interfacial properties.

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  • 17.
    Alvi, Sajid
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Physics, Chalmers University of Technology, SE‐412 96 Göteborg, Sweden.
    Milczarek, Michal
    Department of Mechanics of Materials (ZMM), Institute of Fundamental Technological Research, Polish Academy of Sciences, 02-106 Warsaw, Poland.
    Jarzabek, Dariusz M.
    Department of Mechanics of Materials (ZMM), Institute of Fundamental Technological Research, Polish Academy of Sciences, 02-106 Warsaw, Poland.
    Hedman, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Research Center for Computational Design of Advanced Functional Materials, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1‐1‐1 Umezono, Tsukuba, Ibaraki, 305‐8568 Japan; Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan, 44919 Republic of Korea.
    Gilzad Kohan, Mojtaba
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Levintant-Zayonts, Neonila
    Department of Mechanics of Materials (ZMM), Institute of Fundamental Technological Research, Polish Academy of Sciences, 02-106 Warsaw, Poland.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, 30172 Mestre Venezia, Italy.
    Akhtar, Farid
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Enhanced mechanical, thermal and electrical properties of high‐entropy HfMoNbTaTiVWZr thin film metallic glass and its nitrides2022In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 24, no 9, article id 2101626Article in journal (Refereed)
    Abstract [en]

    The inception of high-entropy alloy promises to push the boundaries for new alloy design with unprecedented properties. This work reports entropy stabilisation of an octonary refractory, HfMoNbTaTiVWZr, high-entropy thin film metallic glass, and derived nitride films. The thin film metallic glass exhibited exceptional ductility of ≈60% strain without fracture and compression strength of 3 GPa in micro-compression, due to the presence of high density and strength of bonds. The thin film metallic glass shows thermal stability up to 750 °C and resistance to Ar-ion irradiation. Nitriding during film deposition of HfMoNbTaTiVWZr thin film of strong nitride forming refractory elements results in deposition of nanocrystalline nitride films with compressive strength, hardness, and thermal stability of up to 10 GPa, 18.7 GPa, and 950 °C, respectively. The high amount of lattice distortion in the nitride films leads to its insulating behaviour with electrical conductivity as low as 200 S cm−1 in the as-deposited film. The design and exceptional properties of the thin film metallic glass and derived nitride films may open up new avenues of development of bulk metallic glasses and the application of refractory-based high entropy thin films in structural and functional applications.

  • 18.
    An, Rong
    et al.
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
    Laaksonen, Aatto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden; Center of Advanced Research in Bionanoconjugates and Biopolymers, “Petru Poni” Institute of Macromolecular Chemistry, Iasi 700469, Romania; State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Wu, Muqiu
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
    Zhu, Yudan
    State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Lu, Xiaohua
    State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Atomic force microscopy probing interactions and microstructures of ionic liquids at solid surfaces2022In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, no 14, p. 11098-11128Article, review/survey (Refereed)
    Abstract [en]

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

  • 19.
    An, Rong
    et al.
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China. Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
    Qiu, Xiuhua
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Riehemann, Kristina
    Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
    Fuchs, Harald
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China. Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
    Controlling the nanoscale friction by layered ionic liquid films2020In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 22, no 26, p. 4941-14952Article in journal (Refereed)
    Abstract [en]

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

  • 20.
    An, Rong
    et al.
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Wei, Yudi
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Qiu, Xiuhua
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Dai, Zhongyang
    High Performance Computing Department, National Supercomputing Center in Shenzhen, Shenzhen, 518055, China.
    Wu, Muqiu
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Gnecco, Enrico
    Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Jena, 07743, Germany.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Zhang, Wenling
    School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
    Ionic liquids on uncharged and charged surfaces: In situ microstructures and nanofriction2022In: Friction, ISSN 2223-7690, E-ISSN 2223-7704, Vol. 10, no 11, p. 1893-1912Article in journal (Refereed)
    Abstract [en]

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

  • 21.
    An, Rong
    et al.
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, P.R. China. Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms, Universität Münster, Münster, Germany .
    Wu, Muqiu
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, P.R. China.
    Li, Jing
    State Key Laboratory of Materials Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, P.R. China.
    Qiu, Xiuhua
    Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, P.R. China.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Li, Jianliang
    Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, P.R. China.
    On the Ionic Liquid Film ‘Pinned’ by Core-Shell Structured Fe3O4@Carbon Nanoparticles and Their Tribological Properties2019In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, no 48, p. 26387-26398Article in journal (Refereed)
    Abstract [en]

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

  • 22.
    An, Rong
    et al.
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
    Wu, Nanhua
    Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China.
    Gao, Qingwei
    College of Environmental and Chemical Engineering, Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, China.
    Dong, Yihui
    Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 76100, Israel.
    Laaksonen, Aatto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden; Center of Advanced Research in Bionanoconjugates and Biopolymers, ‘‘Petru Poni” Institute of Macromolecular Chemistry, Iasi 700469, Romania; State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Fuchs, Harald
    Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China; Center for Nanotechnology (CeNTech), Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
    Integrative Studies of Ionic Liquid Interface Layers: Bridging Experiments, Theoretical Models and Simulations2024In: Nanoscale Horizons, ISSN 2055-6756Article in journal (Refereed)
    Abstract [en]

    Ionic liquids (ILs) are a class of salts existing in the liquid state below 100 C, possessing low volatility, high thermal stability as well as many highly attractive solvent and electrochemical capabilities, etc., making them highly tunable for a great variety of applications, such as lubricants, electrolytes, and soft functional materials. In many applications, ILs are first either physi- or chemisorbed on a solid surface to successively create more functional materials. The functions of ILs at solid surfaces can differ considerably from those of bulk ILs, mainly due to distinct interfacial layers with tunable structures resulting in new ionic liquid interface layer (ILIL) properties and enhanced performance. Due to an almost infinite number of possible combinations among the cations and anions to form ILs, the diversity of various solid surfaces, as well as different external conditions and stimuli, a detailed molecular-level understanding of their structure–property relationship is of utmost significance for a judicious design of IL–solid interfaces with appropriate properties for task-specific applications. Many experimental techniques, such as atomic force microscopy, surface force apparatus, and so on, have been used for studying the ion structuring of ILIL. Molecular Dynamics simulations have been widely used to investigate the microscopic behavior of the ILIL. To interpret and clarify the IL structure and dynamics as well as to predict their properties, it is always beneficial to combine both experiments and simulations as close as possible. In another theoretical model development to bridge the structure and properties of ILIL with performance, thermodynamic (TD) prediction & property modeling has been demonstrated as an effective tool to add the properties and function of the studied nanomaterials. Herein, we present recent findings from applying the multiscale triangle “experiment–molecular simulation–TD modeling” in the studies of ion structuring of ILs in the vicinity of solid surfaces, as well as how it qualitatively and quantitatively correlates to the overall ILs properties, performance, and function. We introduce the most common techniques behind “experiment–molecular simulation–modeling” and how they are applied for studying the ILIL structuring, and we highlight the possibilities of the ILIL structuring in applications such as lubrication and energy storage.

  • 23.
    An, Rong
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing.
    Zhou, Guobing
    School of Chemical Biological and Materials Engineering, University of Oklahoma.
    Zhu, Yudan
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University.
    Zhu, Wei
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University.
    Huang, Liangliang
    School of Chemical Biological and Materials Engineering, University of Oklahoma.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Friction of Ionic Liquid–Glycol Ether Mixtures at Titanium Interfaces: Negative Load Dependence2018In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 5, no 14, article id 1800263Article in journal (Refereed)
    Abstract [en]

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

  • 24.
    An, Rong
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing.
    Zhou, Guobing
    School of Chemical Biological and Materials Engineering, University of Oklahoma.
    Zhu, Yudan
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University.
    Zhu, Wei
    State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University.
    Huang, Liangliang
    School of Chemical Biological and Materials Engineering, University of Oklahoma.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Friction of Ionic Liquid–Glycol Ether Mixtures at Titanium Interfaces: Negative Load Dependence2018In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 5, no 14, article id 1800266Article in journal (Refereed)
    Abstract [en]

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

  • 25.
    Andersson, Anton
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Brander, Linus
    Division of Built Environment—Infrastructure and Concrete, Research Institute of Sweden, SE-501 15 Borås, Sweden.
    Lennartsson, Andreas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Roos, Ake
    Boliden AB, SE-101 20 Stockholm, Sweden.
    Engström, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    A Method for Synthesizing Iron Silicate Slags to Evaluate Their Performance as Supplementary Cementitious Materials2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 14, article id 8357Article in journal (Refereed)
    Abstract [en]

    Utilizing iron silicate copper slag as supplementary cementitious material (SCM) is a means to improve resource efficiency and lower the carbon dioxide emissions from cement production. Despite multiple studies on the performance of these slags in SCM applications, the variations in cooling procedure, grinding, and methods for evaluating reactivity limit the ability to assess the influence of chemical composition on reactivity from the literature data. In this study, a methodology was developed to synthesize iron silicate slags, which were then evaluated for their inherent reactivity using the R-3 calorimeter-based experiments. The results demonstrated that laboratory-scale granulation produced the same reactivity as industrially granulated slag. Furthermore, a synthesized triplicate sample showed high repeatability. Based on these two aspects, this method can be used to systematically study the influence of chemical composition on the inherent reactivity of iron silicate slags while producing results that are directly translatable to industrial slags.

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  • 26.
    Andren, Henrik
    et al.
    Luleå University of Technology.
    Rodushkin, Ilia
    Analytica AB, Luleå, Sweden.
    Stenberg, Anna
    Luleå University of Technology.
    Malinovskiy, Dmitry
    Luleå University of Technology.
    Baxter, Douglas
    Analytica AB, Luleå, Sweden.
    Sources of mass bias and isotope ratio variation in multi-collector ICP-MS: optimization of instrumental parameters based on experimental observations2004In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 19, no 9, p. 1217-1224Article in journal (Refereed)
    Abstract [en]

    In this work, several contributing factors to the observed mass bias in inductively coupled plasma mass spectrometry (ICP-MS) have been identified. Analyses of the isotopic compositions of B deposited on sampler and skimmer cones demonstrate enrichment of [1][0]B on the former and [1][1]B on the latter. Grounding the capacitive discharge system to enhance sensitivity also magnified the level of [1][1]B enrichment on the skimmer cone more than four-fold. This supersonic expansion of the ion beam behind the sampler is confirmed to be an important source of mass bias. Isotopic analyses of the Fe, Zn and Ti leached from used extraction lenses yielded a linear relationship between the levels of lighter isotope depletion and mass ratio. Although consistent with the space-charge effect, the fact that isotopically-heavy deposits were found demonstrates that the ion beam diverges into a relatively wide solid angle in the field-free region behind the skimmer. This severely impairs transmission of, in particular, the lighter isotopes. For a wide range of elements (Li, B, Fe, Ni, Cu, Sb, Ce, Hf and Re), the magnitude of the mass bias was found to be affected by the sample gas flow rate, as well as the distance between the sampler and the end of the torch, i.e., the sampling depth, employed in the Neptune multi-collector ICP-MS instrument. Mathematical analysis of the profiles of intensity variations as a function of these instrumental parameters revealed that the response peaks closer to the torch for the heavier isotopes of all studied elements. Owing to this spatial non-coincidence, tuning for maximum intensity on either isotope will result in sampling from a region where even slight plasma instabilities will be translated into substantial variations in mass bias. Therefore, in-plasma processes also contribute to the degree and temporal stability of mass bias. In light of these findings, recommendations for optimizing multi-collector ICP-MS with respect to obtaining the highest possible precision are presented.

  • 27.
    Andrén, Henrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Studies of artificial mass bias in isotopic measurements by inductively coupled plasma mass spectrometry2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mass spectrometry, and especially inductively coupled plasma mass spectrometry (ICP-MS), suffers heavily from mass bias, or instrumental mass discrimination. The nett result of this effect is the preferential transmission, most often of heavier ions through the mass spectrometer. Most work regarding this phenomenon in ICP-MS dates back quite far, and has been interpreted in terms of the space-charge effect. This means that Coulombic forces acting on the beam of positively charged particles extracted from the ICP result in greater dissipation of lighter, and hence more mobile ions from the beam axis. In this work the importance of the space-charge effect as a universal explanation for mass bias is challenged by the results of high precision measurements of isotope ratios. Other than considering some commonly known sources of isotope ratio measurement bias, a not previously considered mechanism of isotopic fractionation has been investigated, i.e. diffusion in solution. It was established that, indeed, diffusion does lead to isotopic fractionation in solution, and although this is a long term process, may contribute to the minor isotopic variations observed in certain aquatic environments. Furthermore it was established that spectral interferences of argone oxide ions could be discerned from the ions of iron using high resolution ICP-MS, thus eliminating this potential source of artificial fractionation. Most significant was the discovery that the extent of mass bias varied throughout the volume of the plasma, and was further affected by sample characteristics, such as analyte concentration and acid strength. This identifies the plasma itself as the major source of instrumental mass discrimination. Varying the sampling position, i.e. the point at which ions are extracted from the plasma, not only affected the measured isotope ratios, but also the precision of such measurements. From these results, it is not recommended to measure at the sampling position providing maximum signal, since the variability in the isotope ratio is also at its' maximum there. Instead, the ions should be sampled from a point below the maximum, where the stability of the ratios will be better.

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  • 28.
    Antonopoulou, Io
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Sapountzaki, Eleftheria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Christakopoulos, Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    The Inhibitory Potential of Ferulic Acid Derivatives against the SARS-CoV-2 Main Protease: Molecular Docking, Molecular Dynamics, and ADMET Evaluation2022In: Biomedicines, E-ISSN 2227-9059, Vol. 10, no 8, article id 1787Article in journal (Refereed)
    Abstract [en]

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

  • 29.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Amyloidosis of Alzheimer's A peptides: solid-state nuclear magnetic resonance, electron paramagnetic resonance, transmission electron microscopy, scanning transmission electron microscopy and atomic force microscopy studies2004In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 42, no 2, p. 231-246Article in journal (Refereed)
    Abstract [en]

    Aggregation cascade for Alzheimer's amyloid-β peptides, its relevance to neurotoxicity in the course of Alzheimer's disease and experimental methods useful for these studies are discussed. Details of the solid-phase peptide synthesis and sample preparation procedures for Alzheimer's β-amyloid fibrils are given. Recent progress in obtaining structural constraints on Aβ-fibrils from solid-state NMR and scanning transmission electron microscopy (STEM) data is discussed. Polymorphism of amyloid fibrils and oligomers of the 'Arctic' mutant of Aβ(1-40) was studied by 1H,13C solid-state NMR, transmission electron microscopy (TEM) and atomic force microscopy (AFM), and a real-time aggregation of different polymorphs of the peptide was observed with the aid of in situ AFM. Recent results on binding of Cu(II) ions and Al-citrate and Al-ATP complexes to amyloid fibrils, as studied by electron paramagnetic resonance (EPR) and solid-state 27Al NMR techniques, are also presented.

  • 30.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Molecular structure determination: applications in biology2002In: Solid state NMR spectroscopy: principles and applications, Oxford: Blackwell Science , 2002, p. 280-390Chapter in book (Other academic)
  • 31.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Polymorphism of Alzheimer´s A-beta Amyloid Fibrils2006In: Modern Magnetic Resonance: Applications in Chemistry, Biological and Marine Sciences, Dordrecht: Encyclopedia of Global Archaeology/Springer Verlag, 2006, p. 15-23Chapter in book (Other academic)
    Abstract [en]

    An overview of the strategy and experimental solid-state NMR, STEM, and AFM methods useful for obtaining structural constraints on Alzheimer’s amyloid-β peptide fibrils is presented. Polymorphism of amyloid fibrils and the relevance to neurotoxicity is discussed.

  • 32.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Polymorphism of Alzheimer´s A-beta Amyloid Fibrils and Oligomers2017In: Modern Magnetic Resonance / [ed] Graham A. Webb, Springer International Publishing , 2017, p. 1-15Chapter in book (Other academic)
    Abstract [en]

    An overview of the strategy and experimental solid-state NMR, STEM, and AFM methods useful for obtaining structural constraints on Alzheimer’s amyloid-β peptide fibrils is presented. Polymorphism of amyloid fibrils and the relevance to neurotoxicity is discussed.

  • 33.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Polymorphism of Alzheimer’s Aβ Amyloid Fibrils and Oligomers2018In: Modern Magnetic Resonance / [ed] Graham A. Webb, Cham: Springer, 2018, p. 333-347Chapter in book (Refereed)
    Abstract [en]

    An overview of the strategy and experimental solid-state NMR, TEM, STEM, and AFM methods useful for obtaining atomic-level-resolution structural models of Alzheimer’s amyloid-β peptide fibrils and oligomers is presented. Polymorphism of amyloid fibrils and oligomers and the relevance to neurotoxicity is discussed.

  • 34.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Polymorphism of Amyloid Fibrils and Aggregation Kinetics of Alzheimer's Abeta peptides: solid state NMR, EM and AFM studies2005In: NMR in Molecular Biology: EuroConference on Structural Genomics: Structure, Dynamics and Interactions of Biomolecules, 2005, p. 35-Conference paper (Refereed)
  • 35.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sideband manipulation in magic-angle-spinning nuclear magnetic resonance1999In: Progress in nuclear magnetic resonance spectroscopy, ISSN 0079-6565, E-ISSN 1873-3301, Vol. 35, no 3, p. 203-266Article in journal (Refereed)
  • 36.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Balbach, John J.
    Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda.
    Leapman, Richard D.
    Division of Bioengineering and Physical Science, Office of Research Services, National Institutes of Health, Bethesda.
    Rizzo, Nancy W.
    Division of Bioengineering and Physical Science, Office of Research Services, National Institutes of Health, Bethesda.
    Reed, Jennifer
    Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda.
    Tycko, Robert
    National Institutes of Health, Bethesda.
    Multiple quantum solid-state NMR indicates a parallel, not antiparallel, organization of β-sheets in Alzheimer's β-amyloid fibrils2000In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 97, no 24, p. 13045-13050Article in journal (Refereed)
    Abstract [en]

    Senile plaques associated with Alzheimer's disease contain deposits of fibrils formed by 39- to 43-residue β-amyloid peptides with possible neurotoxic effects. X-ray diffraction measurements on oriented fibril bundles have indicated an extended β-sheet structure for Alzheimer's β-amyloid fibrils and other amyloid fibrils, but the supramolecular organization of the β-sheets and other structural details are not well established because of the intrinsically noncrystalline, insoluble nature of amyloid fibrils. Here we report solid-state NMR measurements, using a multiple quantum (MQ) 13C NMR technique, that probe the β-sheet organization in fibrils formed by the full-length, 40-residue β-amyloid peptide (Aβ1-40). Although an antiparallel β-sheet organization often is assumed and is invoked in recent structural models for full-length β-amyloid fibrils, the MQNMR data indicate an in-register, parallel organization. This work provides site-specific, atomic-level structural constraints on full-length β-amyloid fibrils and applies MQNMR to a significant problem in structural biology.

  • 37.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Balbach, John J.
    National Institutes of Health.
    Tycko, Robert
    National Institutes of Health.
    Site-Specific Identification of Non-ß-Strand Conformations in Alzheimer's ß-Amyloid Fibrils by Solid-State NMR2003In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 84, no 5, p. 3326-3335Article in journal (Refereed)
    Abstract [en]

    The most well-established structural feature of amyloid fibrils is the cross-ß motif, an extended ß-sheet structure formed by ß-strands oriented perpendicular to the long fibril axis. Direct experimental identification of non-ß-strand conformations in amyloid fibrils has not been reported previously. Here we report the results of solid-state NMR measurements on amyloid fibrils formed by the 40-residue ß-amyloid peptide associated with Alzheimer's disease (Aß1-40), prepared synthetically with pairs of 13C labels at consecutive backbone carbonyl sites. The measurements probe the peptide backbone conformation in residues 24-30, a segment where a non-ß-strand conformation has been suggested by earlier sequence analysis, cross-linking experiments, and molecular modeling. Data obtained with the fpRFDR-CT, DQCSA, and 2D MAS exchange solid-state NMR techniques, which provide independent constraints on the and backbone torsion angles between the labeled carbonyl sites, indicate non-ß-strand conformations at G25, S26, and G29. These results represent the first site-specific identification and characterization of non-ß-strand peptide conformations in an amyloid fibril

  • 38. Antzutkin, Oleg
    et al.
    Benetis, N. P.
    Lindgren, M.
    Linköping University.
    Lund, A.
    Molecular motion of the Morpholin-1-yl radical in CF2 ClCFCl2 as studied by ESR: use of residual anisotrophy of powder spectra to extract dynamics1993In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 169, no 2, p. 195-205Article in journal (Refereed)
    Abstract [en]

    The dynamics of the deprotonated neutral morpholin-1-yl radical, trapped in a halocarbon matrix, CF2ClCFCl2, has been studied utilizing electron spin resonance (ESR) spectroscopy. The experimental lineshapes of the radical exhibit an alterating line-width effect in the temperature range 105-144 K. The major changes of the ESR lineshape were governed by the averaging of the nitrogen hyperfine anisotropy while no exchange of the isotropic hyperfine coupling constants was observed. Geometrical parameters specifying the restricted anisotropic rotation of the whole radical trapped in the matrix could be extracted. Two methods for simulating anisotropic exchange broadened ESR spectra, the secular and non-perturbative, were utilized to investigate the dynamics of the radical. A surprisingly simple ''three-site'' jump model with a barrier of almost-equal-to 3.6 kcal/mol can be applied in the simulation of the experimental spectra. It has been shown that the secular method cannot reproduce the exchange broadened ESR spectra of systems with large hyperfine anisotropy undergoing large internal reorganisation.

  • 39.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Filippov, Andrei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Wong, Alan
    University of Warwick.
    Baldus, Johanna Becker
    University of Warwick.
    Hung, Ivan
    University of Warwick.
    Kukol, A.
    University of Warwick.
    Brown, Steven P.
    University of Warwick.
    Smith, Mark E.
    University of Warwick.
    Dupree, Ray
    University of Warwick.
    Exploring solid-state 17O NMR to distinguish secondary structures in Alzheimer's Aβ fibrils2009Conference paper (Refereed)
  • 40.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Filippov, Andrei
    Wong, Alan
    University of Warwick.
    Baldus, Johanna
    University of Warwick.
    Hung, Ivan
    University of Warwick.
    Kukol, A.
    University of Warwick.
    Brown, Steven P.
    University of Warwick.
    Smith, Mark E.
    University of Warwick.
    Dupree, Ray
    University of Warwick.
    Exploring solid-state 17O NMR to distinguish secondary structures in Alzheimer's Aβ fibrils2009In: Euromar 2009: Magnetics Resonance Conference, 5-9 July 2009, Göteborg, Sweden. Programme and Abstract Book, 2009, p. 107-Conference paper (Other academic)
    Abstract [en]

    It has been shown by a large number of studies that Alzheimer's disease (AD) amyloid-β-peptide (Aβ) deposits contribute directly to the disease's progressive neurodegeneration. Aggregation cascade for Aβ peptides, its relevance to neurotoxicity in the course of AD, various factors modulating Aβ aggregation kinetics and experimental methods useful for these studies were recently discussed [1]. Results of Tycko and co-workers point at neurotoxicity in vitro of the two different types of Alzheimer's amyloid fibrils dispersed by ultrasonication into small fragments [2]. The high toxicity of Aβ oligomers in vitro has been discussed by Stege et. al who have found that the molecular chaperone αB-crystallin prevents Aβ from forming amyloid fibrils but nevertheless enhances Aβ toxicity [3]. Glabe and co-workes successfully prepared antibodies for Aβ oligomers and small spherical aggregates using nanogold technology [4]. They also have shown that these antibodies decrease toxicity of Aβ for SH-SY5Y human neuroblastoma cell cultures in vitro [4]. In this concern both structure of Aβ-oligomers/fibrils and the specific  interaction (aggregation/fusion) of Aβ peptides with nerve cell membranes is of a particular importance [5].We explore Solid-State 17O NMR on selectively 17O,13C,15N-labeled Aβ(1-40), Aβ(11-25) and Ac-Aβ(16-22)-NH2 peptides to distinguish a parallel and anti-parallel β-sheet secondary structures in β-NH2 peptides to distinguish a parallel and anti-parallel β-sheet secondary structures in amyloid fibrils. Aβ(1-40) fibrils form in-registry parallel β-sheets [6], while Aβ(11-25) [7] and Ac-Aβ(16-22)-NH2 [8] form different anti-parallel β-sheet structures, which were previously identified β-NH2 [8] form different anti-parallel β-sheet structures, which were previously identified by 13C multiple-quantum and 13C{15N} REDOR solid-state NMR. In our unpublished work presented here it was found that 17O NMR chemical shifts are sensitive to the type of the secondary structure, i. e. a parallel vs. an anti-parallel β-sheet structures, while the quadrupolar parameters of 17O nuclei unexpectedly do not vary beyond the error limits in the simulated lineshapes of both fibrillized and unfibrillized peptide systems. Results of more advanced solidstate NMR techniques to measure heteronuclear distances, 15N{17O}-REAPDOR, 15N{17O}-TRAPDOR and 17O{15N}-REDOR on selectively 17O-Val18 and 15N-Phe20 labeled Ac-Aβ(16-22)-NH2 fibrils will be also discussed. These novel solid-state NMR experiments will provide additional tools for measuring hydrogen bonding in different secondary structures of peptides in amyloid fibrils.[1.] O.N.Antzutkin, Magn. Reson. Chem. 42 (2004) 231-246; [2.] A.Petkova et al. Science 307 (2005) 262-265; [3.] G.J.J.Stege, et al. Biochem. Biophys. Res. Comm., 262 (1999) 152-156;[4.] R.Kayed et al. Science, 300 (2003) 486-489; [5.] M.Bokvist, et al. J. Mol. Biol. 335 (2004) 1039-1049; [6.] O.N. Antzutkin, et al. Proc. Nat. Acad. Sci, U.S.A., 97 (2000) 13045-13050;[7.] A.T. Petkova, et al. J. Mol. Biol., 335 (2004) 247-260;[8.] J.J. Balbach, Y. (2000) 13045-13050; [9] A.T. Petkova, (2004) 247-260; [10] J.J. Balbach, Y.Ishii, O.N. Antzutkin, et al. Biochemistry 39 (2000) 13748-13759.

  • 41.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Iuga, Dino
    Department of Physics, Warwick University, Coventry.
    Filippov, Andrei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Kelly, Robert T.
    Department of Physics, Warwick University, Coventry.
    Becker-Baldus, Johanna
    Department of Physics, Warwick University, Coventry.
    Brown, Steven P.
    Department of Physics, Warwick University, Coventry.
    Dupree, Ray
    Department of Physics, Warwick University, Coventry.
    Hydrogen bonding in Alzheimer’s amyloid-β fibrils probed by 15N{17O} REAPDOR solid-state NMR spectroscopy2012In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 51, no 41, p. 10289-10292Article in journal (Refereed)
    Abstract [en]

    An exclusive label: 15N{17O} REAPDOR NMR was used to validate intermolecular C17O⋅⋅⋅H15N hydrogen bonding in Ac-Aβ(16–22)-NH2 (see scheme) and Aβ(11–25) amyloid fibrils, which are associated with Alzheimer’s disease, by selectively labeling them with 17O and 15N. This method was effective for confirming the structure of these fibrils, and could be useful for a number of other biological samples.

  • 42.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Iuga, Dinu
    Department of Physics, Warwick University, Coventry.
    Filippov, Andrei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Kelly, Robert T.
    Department of Physics, Warwick University, Coventry.
    Becker-Baldus, Johanna
    Department of Physics, Warwick University, Coventry.
    Brown, Steven P.
    Department of Physics, Warwick University, Coventry.
    Dupree, Ray
    Department of Physics, Warwick University, Coventry.
    Hydrogen bonding in Alzheimer’s amyloid-β fibrils probed by 15N{17O} REAPDOR solid-state NMR spectroscopy2012In: Angewandte Chemie, ISSN 0044-8249, Vol. 124, no 41, p. 10435-10438Article in journal (Refereed)
    Abstract [en]

    Nach selektiver Markierung mit 17O und 15N wurden mithilfe von 15N{17O}-REAPDOR-NMR-Spektroskopie intermolekulare C17O⋅⋅⋅H15N-Wasserstoffbrücken in Ac-Aβ(16–22)-NH2- (siehe Schema) und Aβ(11–25)-Amyloidfibrillen untersucht, die mit der Alzheimer-Krankheit in Verbindung gebracht werden. Die Methode, die eine Bestätigung für die Struktur dieser Fibrillen lieferte, könnte auch im Zusammenhang mit anderen biologischen Proben nützlich sein.

  • 43.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Kota, Hanumantha Rao
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Ikumapayi, Fatai
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Holmgren, Allan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Gunneriusson, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Johansson, Björn
    New Boliden AB.
    Berggren, Andreas
    New Boliden AB.
    Larsson, Anna-Carin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Bhuiyan, Iftekhar Uddin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Forsmo, Seija
    LKAB.
    Interactions in multi-component mineral systems2011Conference paper (Other academic)
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  • 44.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Kota, Hanumantha Rao
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Ikumapayi, Fatai
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Johansson, Björn
    New Boliden AB.
    Berggren, Andreas
    New Boliden AB.
    Larsson, Anna-Carin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Holmgren, Allan
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mouzon, Johanne
    Bhuiyan, Iftekhar Uddin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Forsmo, Seija
    LKAB.
    Interactions in multi-component mineral systems2010Conference paper (Other academic)
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  • 45.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Leapman, Richard D.
    Division of Physical Science, Office of Research Services, National Institutes of Health, Bethesda.
    Balbach, John J.
    Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda.
    Tycko, Robert
    Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda.
    Supramolecular structural constraints on Alzheimer's β-amyloid fibrils from electron microscopy and solid-state nuclear magnetic resonance2002In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 41, no 51, p. 15436-15450Article in journal (Refereed)
    Abstract [en]

    We describe electron microscopy (EM), scanning transmission electron microscopy (STEM), and solid-state nuclear magnetic resonance (NMR) measurements on amyloid fibrils formed by the 42-residue β-amyloid peptide associated with Alzheimer's disease (Aβ1-42) and by residues 10-35 of the full-length peptide (Aβ10-35). These measurements place constraints on the supramolecular structure of the amyloid fibrils, especially the type of β-sheets present in the characteristic amyloid cross-β structural motif and the assembly of these β-sheets into a fibril. EM images of negatively stained Aβ10-35 fibrils and measurements of fibril mass per length (MPL) by STEM show a strong dependence of fibril morphology and MPL on pH. Aβ10-35 fibrils formed at pH 3.7 are single "protofilaments" with MPL equal to twice the value expected for a single cross-β layer. Aβ10-35 fibrils formed at pH 7.4 are apparently pairs of protofilaments or higher order bundles. EM and STEM data for Aβ1-42 fibrils indicate that protofilaments with MPL equal to twice the value expected for a single cross-β layer are also formed by Aβ1-42 and that these protofilaments exist singly and in pairs at pH 7.4. Solid-state NMR measurements of intermolecular distances in Aβ10-35 fibrils, using multiple-quantum 13C NMR, 13C-13C dipolar recoupling, and 15N-13C dipolar recoupling techniques, support the in-register parallel β-sheet organization previously established by Lynn, Meredith, Botto, and co-workers [Benzinger et al. (1998) Proc. Natl. Acad. Sci. U.S.A. 95, 13407-13412; Benzinger et al. (2000) Biochemistry 39, 3491-3499] and show that this β-sheet organization is present at pH 3.7 as well as pH 7.4 despite the differences in fibril morphology and MPL. Solid-state NMR measurements of intermolecular distances in Aβ1-42 fibrils, which represent the first NMR data on Aβ1-42 fibrils, also indicate an in-register parallel β-sheet organization. These results, along with previously reported data on Aβ1-40 fibrils, suggest that the supramolecular structures of Aβ10-35, Aβ1-40, and Aβ1-42 fibrils are quite similar. A schematic structural model of these fibrils, consistent with known experimental EM, STEM, and solid-state NMR data, is presented.

  • 46.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Lee, Young K.
    Stockholm University.
    Levitt, Malcolm H.
    Stockholm University.
    13C and15N-chemical shift anisotropy of ampicillin and penicillin-V studied by 2D-PASS and CP/MAS NMR1998In: Journal of magnetic resonance, ISSN 1090-7807, E-ISSN 1096-0856, Vol. 135, no 1, p. 144-155Article in journal (Refereed)
    Abstract [en]

    The principal values of the chemical shift tensors of all13C and15N sites in two antibiotics, ampicillin and penicillin-V, were determined by 2-dimensionalphaseadjustedspinningsideband (2D-PASS) and conventional CP/MAS experiments. The13C and15N chemical shift anisotropies (CSA), and their confidence limits, were evaluated using a Mathematica program. The CSA values suggest a revised assignment of the 2-methyl13C sites in the case of ampicillin. We speculate on a relationship between the chemical shift principal values of many of the13C and15N sites and the β-lactam ring conformation

  • 47. Antzutkin, Oleg
    et al.
    Levitt, Malcolm H.
    Stockholm University.
    Centerband phase shift in the TOSS spectra of a magic-angle-spinning single crystal1996In: Journal of Magnetic Resonance - Series A, ISSN 1064-1858, E-ISSN 1096-0864, Vol. 118, no 2, p. 295-298Article in journal (Refereed)
  • 48.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Levitt, Malcolm H.
    Stockholm University.
    Coherence transfer signals in the rotational resonance NMR of a spinning single crystal2000In: Journal of magnetic resonance, ISSN 1090-7807, E-ISSN 1096-0856, Vol. 147, no 1, p. 147-151Article in journal (Refereed)
    Abstract [en]

    A recent analysis of rotational resonance lineshapes (M. Helmle et al., J. Magn. Reson. 140, 379-403, 1999) predicted the existence of coherence transfer signals, which are generated by mechanically induced coherence transfer during the detection process. These signals correspond to the generation of observable coherences at spin sites that have no magnetization at the beginning of the observation interval but which acquire coherence while the detection is underway. The coherence transfer signals disappear for powder samples in conventional magic-angle-spinning solid-state NMR experiments. In this Communication, we report the successful detection of coherence transfer signals in rotor-synchronized experiments performed on a single crystal of [1,2-13C2]glycine.

  • 49. Antzutkin, Oleg
    et al.
    Lindgren, M.
    Linköping University.
    Koptyug, A. V.
    Lund, A.
    Optically dectected ESR (OD-ESR) of iron-radical pairs in colored solutions: observation of transient trans-Azobenzene radical cation1993In: Applied Magnetic Resonance, ISSN 0937-9347, E-ISSN 1613-7507, Vol. 5, no 1, p. 77-86Article in journal (Refereed)
    Abstract [en]

    Trans-azobenzene dissolved in different liquid hydrocarbons absorbs fluorescence arising from all acceptors previously used in Fluorescence Detected Magnetic Resonance (FDMR) and Optically Detected ESR (OD ESR) spectroscopy making optical detection impossible. In this report a new acceptor, rubrene, having sufficient quantum yield of fluorescence in the red band 550-620 nm, has been proven successful. OD ESR spectra of the radical-ion pair trans-azobenzene+/rubrene- were detected in liquid squalane (2,6,10,15,19,23-hexamethyl-tetracosane) solution in the temperature range 294-243 K. The experimental isotropic hyperfine splittings of the radical cation of trans-azobenzene (a(N) = 1.4 mT) have been compared with those from MNDO/INDO calculations and with those of earlier work using freon matrix studies.

  • 50. Antzutkin, Oleg
    et al.
    Lindgren, M.
    Linköping University.
    Lund, A.
    Sjöqvist, L.
    Observation of Piperidine aggregation and of Hydrogen-proton transfer between Piperidine radical cations and Piperidine molecules in Freon matrice: an E.S.R. study at cryogenic temperaturs1992In: Journal of the Chemical Society. Chemical communications, ISSN 0022-4936, no 21, p. 1547-1550Article in journal (Refereed)
    Abstract [en]

    Piperidine forms small aggregates in most Freon matrices at cryogenic temperatures; upon X-irradiation, hydrogen-proton transfer between piperidine radical cations and piperidine molecules occurs.

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