scholarly journals Effect of 1-Ethyl-3-methylimidazolium Tetrafluoroborate and Acetate Ionic Liquids on Stability and Amyloid Aggregation of Lysozyme

2022 ◽  
Vol 23 (2) ◽  
pp. 783
Author(s):  
Diana Fedunova ◽  
Andrea Antosova ◽  
Jozef Marek ◽  
Vladimir Vanik ◽  
Erna Demjen ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Amyloid Fibrils ◽  
Cd Spectroscopy ◽  
Dependent Manner ◽  
Amyloid Aggregation ◽  
Scanning Calorimetry ◽  
Docking Calculations ◽  
Fibril Morphology ◽  
Time Frames ◽  
Kinetics Of

Amyloid fibrils draw attention as potential novel biomaterials due to their high stability, strength, elasticity or resistance against degradation. Therefore, the controlled and fast fibrillization process is of great interest, which raises the demand for effective tools capable of regulating amyloid fibrillization. Ionic liquids (ILs) were identified as effective modulators of amyloid aggregation. The present work is focused on the study of the effect of 1-ethyl-3-methyl imidazolium-based ILs with kosmotropic anion acetate (EMIM-ac) and chaotropic cation tetrafluoroborate (EMIM-BF4) on the kinetics of lysozyme amyloid aggregation and morphology of formed fibrils using fluorescence and CD spectroscopy, differential scanning calorimetry, AFM with statistical image analysis and docking calculations. We have found that both ILs decrease the thermal stability of lysozyme and significantly accelerate amyloid fibrillization in a dose-dependent manner at concentrations of 0.5%, 1% and 5% (v/v) in conditions and time-frames when no fibrils are formed in ILs-free solvent. The effect of EMIM-BF4 is more prominent than EMIM-ac due to the different specific interactions of the anionic part with the protein surface. Although both ILs induced formation of amyloid fibrils with typical needle-like morphology, a higher variability of fibril morphology consisting of a different number of intertwining protofilaments was identified for EMIM-BF4.

Computational analysis of the effect of [Tea][Ms] and [Tea][H2PO4] ionic liquids on the structure and stability of Aβ(17–42) amyloid fibrils

2021 ◽  
Vol 23 (11) ◽  
pp. 6695-6709
Author(s):  
D. Gobbo ◽  
A. Cavalli ◽  
P. Ballone ◽  
A. Benedetto
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Ionic Liquids ◽  
Liquid Water ◽  
Computational Analysis ◽  
Amyloid Fibrils ◽  
Aβ Peptides ◽  
Structure And Stability ◽  
Water Solutions ◽  
Kinetics Of

Tight coordination of peptides by organic anions driven by hydrogen bonding affects the fibrillation kinetics of Aβ peptides in ionic liquid/water solutions.

scholarly journals Dry-Jet Wet Spinning of Thermally Stable Lignin-Textile Grade Polyacrylonitrile Fibers Regenerated from Chloride-Based Ionic Liquids Compounds

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3687
Author(s):  
Muhannad Al Aiti ◽  
Amit Das ◽  
Mikko Kanerva ◽  
Maija Järventausta ◽  
Petri Johansson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Ionic Liquids ◽  
High Performance ◽  
Paper Industry ◽  
Mechanical Tests ◽  
Coagulation Bath ◽  
Scanning Calorimetry ◽  
The Impact ◽  
Kinetics Of

In this paper, we report on the use of amorphous lignin, a waste by-product of the paper industry, for the production of high performance carbon fibers (CF) as precursor with improved thermal stability and thermo-mechanical properties. The precursor was prepared by blending of lignin with polyacrylonitrile (PAN), which was previously dissolved in an ionic liquid. The fibers thus produced offered very high thermal stability as compared with the fiber consisting of pure PAN. The molecular compatibility, miscibility, and thermal stability of the system were studied by means of shear rheological measurements. The achieved mechanical properties were found to be related to the temperature-dependent relaxation time (consistence parameter) of the spinning dope and the diffusion kinetics of the ionic liquids from the fibers into the coagulation bath. Furthermore, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical tests (DMA) were utilized to understand in-depth the thermal and the stabilization kinetics of the developed fibers and the impact of lignin on the stabilization process of the fibers. Low molecular weight lignin increased the thermally induced physical shrinkage, suggesting disturbing effects on the semi-crystalline domains of the PAN matrix, and suppressed the chemically induced shrinkage of the fibers. The knowledge gained throughout the present paper allows summarizing a novel avenue to develop lignin-based CF designed with adjusted thermal stability.

scholarly journals Exploring the potential of deep-blue autofluorescence for monitoring amyloid fibril formation and dissociation

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7554
Author(s):  
Mantas Ziaunys ◽  
Tomas Sneideris ◽  
Vytautas Smirnovas
Keyword(s):  
Neurodegenerative Disorders ◽  
Amyloid Fibrils ◽  
Amyloid Fibril ◽  
Fibril Formation ◽  
Amyloid Formation ◽  
Amyloid Aggregation ◽  
Deep Blue ◽  
Amyloid Fibril Formation ◽  
Kinetics Of ◽  
Kinetics Of Fibril Formation

Protein aggregation into amyloid fibrils has been linked to multiple neurodegenerative disorders. Determining the kinetics of fibril formation, as well as their structural stability are important for the mechanistic understanding of amyloid aggregation. Tracking both fibril association and dissociation is usually performed by measuring light scattering of the solution or fluorescence of amyloid specific dyes, such as thioflavin-T. A possible addition to these methods is the recently discovered deep-blue autofluorescence (dbAF), which is linked to amyloid formation. In this work we explore the potential of this phenomenon to monitor amyloid fibril formation and dissociation, as well as show its possible relation to fibril size rather than amyloid structure.

Influence of Brain Gangliosides on the Formation and Properties of Supported Lipid Bilayers for Binding Kinetics Studies

2018 ◽  
Author(s):  
Luke Jordan ◽  
Nathan Wittenberg
Keyword(s):  
Lipid Bilayers ◽  
Binding Kinetics ◽  
Supported Lipid Bilayers ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Supported Lipid Bilayer ◽  
Head Groups ◽  
Lipid Diffusion ◽  
Kinetics Of ◽  
Brain Gangliosides

This is a comprehensive study of the effects of the four major brain gangliosides (GM1, GD1b, GD1a, and GT1b) on the adsorption and rupture of phospholipid vesicles on SiO2 surfaces for the formation of supported lipid bilayer (SLB) membranes. Using quartz crystal microbalance with dissipation monitoring (QCM-D) we show that gangliosides GD1a and GT1b significantly slow the SLB formation process, whereas GM1 and GD1b have smaller effects. This is likely due to the net ganglioside charge as well as the positions of acidic sugar groups on ganglioside glycan head groups. Data is included that shows calcium can accelerate the formation of ganglioside-rich SLBs. Using fluorescence recovery after photobleaching (FRAP) we also show that the presence of gangliosides significantly reduces lipid diffusion coefficients in SLBs in a concentration-dependent manner. Finally, using QCM-D and GD1a-rich SLB membranes we measure the binding kinetics of an anti-GD1a antibody that has similarities to a monoclonal antibody that is a hallmark of a variant of Guillain-Barre syndrome.

Study of nickel-molybdenum catalysts for methanation of carbon monoxide

1980 ◽  
Vol 45 (3) ◽  
pp. 783-790 ◽  
Author(s):  
Petr Taras ◽  
Milan Pospíšil
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Mixed Oxides ◽  
Minor Component ◽  
Fast Neutrons ◽  
Scanning Calorimetry ◽  
Low Concentrations ◽  
Γ Rays ◽  
Molybdenum Catalysts ◽  
Kinetics Of

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoOx systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO2. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.

scholarly journals Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1686
Author(s):  
Andrey Galukhin ◽  
Roman Nosov ◽  
Ilya Nikolaev ◽  
Elena Melnikova ◽  
Daut Islamov ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Single Step ◽  
Polymerization Kinetics ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Polymerization Product ◽  
The One ◽  
Kinetics Of

A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand.

scholarly journals Isothermal Vulcanization and Non-Isothermal Degradation Kinetics of XNBR/Epoxy/XNBR-g-Halloysite Nanotubes (HNT) Nanocomposites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2872
Author(s):  
Seyed Mohamad Reza Paran ◽  
Ghasem Naderi ◽  
Elnaz Movahedifar ◽  
Maryam Jouyandeh ◽  
Krzysztof Formela ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Degradation Kinetics ◽  
Halloysite Nanotubes ◽  
Butadiene Rubber ◽  
Order Model ◽  
Scanning Calorimetry ◽  
Theoretical Methods ◽  
Vulcanization Kinetics ◽  
Kinetics Of ◽  
Thermal Stability Of

The effect of several concentrations of carboxylated nitrile butadiene rubber (XNBR) functionalized halloysite nanotubes (XHNTs) on the vulcanization and degradation kinetics of XNBR/epoxy compounds were evaluated using experimental and theoretical methods. The isothermal vulcanization kinetics were studied at various temperatures by rheometry and differential scanning calorimetry (DSC). The results obtained indicated that the nth order model could not accurately predict the curing performance. However, the autocatalytic approach can be used to estimate the vulcanization reaction mechanism of XNBR/epoxy/XHNTs nanocomposites. The kinetic parameters related to the degradation of XNBR/epoxy/XHNTs nanocomposites were also assessed using thermogravimetric analysis (TGA). TGA measurements suggested that the grafted nanotubes strongly enhanced the thermal stability of the nanocomposite.

scholarly journals Thermal Stability and Decomposition Kinetics of 1-Alkyl-2,3-Dimethylimidazolium Nitrate Ionic Liquids: TGA and DFT Study

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2560
Author(s):  
Jianwen Meng ◽  
Yong Pan ◽  
Fan Yang ◽  
Yanjun Wang ◽  
Zhongyu Zheng ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Density Functional Theory ◽  
Ionic Liquids ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Nitrogen Atmosphere ◽  
Decomposition Kinetics ◽  
Heating Rates ◽  
Functional Theory ◽  
Kinetics Of

The thermal stability and decomposition kinetics analysis of 1-alkyl-2,3-dimethylimidazole nitrate ionic liquids with different alkyl chains (ethyl, butyl, hexyl, octyl and decyl) were investigated by using isothermal and nonisothermal thermogravimetric analysis combined with thermoanalytical kinetics calculations (Kissinger, Friedman and Flynn-Wall-Ozawa) and density functional theory (DFT) calculations. Isothermal experiments were performed in a nitrogen atmosphere at 240, 250, 260 and 270 °C. In addition, the nonisothermal experiments were carried out in nitrogen and air atmospheres from 30 to 600 °C with heating rates of 5, 10, 15, 20 and 25 °C/min. The results of two heating modes, three activation energy calculations and density functional theory calculations consistently showed that the thermal stability of 1-alkyl-2,3-dimethylimidazolium nitrate ionic liquids decreases with the increasing length of the alkyl chain of the substituent on the cation, and then the thermal hazard increases. This study could provide some guidance for the safety design and use of imidazolium nitrate ionic liquids for engineering.

Effects of additives on the cure kinetics of vinyl ester pultrusion resins

2021 ◽  
pp. 002199832110015
Author(s):  
Alexander Vedernikov ◽  
Yaroslav Nasonov ◽  
Roman Korotkov ◽  
Sergey Gusev ◽  
Iskander Akhatov ◽  
...  
Keyword(s):  
Vinyl Ester ◽  
Mean Squared Error ◽  
Cure Kinetics ◽  
Zinc Stearate ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Predicted Values ◽  
Kinetics Of ◽  
Final Degree

Pultrusion is a highly efficient composite manufacturing process. To accurately describe pultrusion, an appropriate model of resin cure kinetics is required. In this study, we investigated cure kinetics modeling of a vinyl ester pultrusion resin (Atlac 430) in the presence of aluminum hydroxide (Al(OH)3) and zinc stearate (Zn(C18H35O2)2) as processing additives. Herein, four different resin compositions were studied: neat resin composition, composition with Al(OH)3, composition comprising Zn(C18H35O2)2, and composition containing both Al(OH)3 and Zn(C18H35O2)2. To analyze each composition, we performed differential scanning calorimetry at the heating rates of 5, 7.5, and 10 K/min. To characterize the cure kinetics of Atlac 430, 16 kinetic models were tested, and their performances were compared. The model based on the [Formula: see text]th-order autocatalytic reaction demonstrated the best results, with a 4.5% mean squared error (MSE) between the experimental and predicted data. This study proposes a method to reduce the MSE resulting from the simultaneous melting of Zn(C18H35O2)2. We were able to reduce the MSE by approximately 34%. Numerical simulations conducted at different temperatures and pulling speeds demonstrated a significant influence of resin composition on the pultrusion of a flat laminate profile. Simulation results obtained for the 600 mm long die block at different die temperatures (115, 120, 125, and 130 °C) showed that for a resin with a final degree of cure exceeding 95% at the die exit, the maximum difference between the predicted values of pulling speed for a specified set of compositions may exceed 1.7 times.

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