| 1. |
- Butylina, Svetlana, et al.
(författare)
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Cellulose Nanocomposite Hydrogels : From Formulation to Material Properties
- 2020
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Poly(vinyl alcohol) (PVA) hydrogels produced using the freeze-thaw method have attracted attention for a long time since their first preparation in 1975. Due to the importance of polymer intrinsic features and the advantages associated with them, they are very suitable for biomedical applications such as tissue engineering and drug delivery systems. On the other hand, there is an increasing interest in the use of biobased additives such as cellulose nanocrystals, CNC. This study focused on composite hydrogels which were produced by using different concentrations of PVA (5 and 10%) and CNC (1 and 10 wt.%), also, pure PVA hydrogels were used as references. The main goal was to determine the impact of both components on mechanical, thermal, and water absorption properties of composite hydrogels as well as on morphology and initial water content. It was found that PVA had a dominating effect on all hydrogels. The effect of the CNC addition was both concentration-dependent and case-dependent. As a general trend, addition of CNC decreased the water content of the prepared hydrogels, decreased the crystallinity of the PVA, and increased the hydrogels compression modulus and strength to some extent. The performance of composite hydrogels in a cyclic compression test was studied; the hydrogel with low PVA (5) and high CNC (10) content showed totally reversible behavior after 10 cycles.
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| 2. |
- Conn, Charlotte E, et al.
(författare)
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Membrane Protein Structures in Lipid Bilayers; Small-Angle Neutron Scattering With Contrast-Matched Bicontinuous Cubic Phases
- 2020
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Ingår i: Frontiers in chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- . Deuterated vesicles can be used to obtain the radius of gyration of membrane proteins, but protein-protein interference effects within the vesicles severely limits this method such that the protein structure cannot be modeled. We show herein that different membrane protein conformations can be distinguished within the lipid bilayer of the bicontinuous cubic phase using contrast-matching. Time-resolved studies performed using SANS illustrate the complex phase behavior in lyotropic liquid crystalline systems and emphasize the importance of this development. We believe that studying membrane protein structures and phase behavior in contrast-matched lipid bilayers will advance both biological and pharmaceutical applications of membrane-associated proteins, biosensors and food science.
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| 3. |
- Filippov, Andrei, PhD, 1957-, et al.
(författare)
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Diffusion of Ions in Phosphonium Orthoborate Ionic Liquids Studied by 1H and 11B Pulsed Field Gradient NMR
- 2020
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Non-halogenated boron-based ionic liquids (ILs) composed of phosphonium cations and chelated orthoborate anions have high hydrolytic stability, low melting point and exceptional properties for various applications. This study is focused on ILs with the same type of cation, trihexyltetradecylphosphonium ([P6,6,6,14]+), and two orthoborate anions, such as bis(salicylato)borate ([BScB]−) and bis(oxalato)borate ([BOB]−). We compare the results of this study with our previous studies on ILs with bis(mandelato)borate ([BMB]−) and a variety of different cations (tetraalkylphosphonium, dialkylpyrrolidinium and dialkylimidazolium). The ion dynamics and phase behavior of these ILs is studied using 1H and 11B pulsed-field-gradient (PFG) NMR. PFG NMR is demonstrated to be a useful tool to elucidate the dynamics of ions in this class of phosphonium orthoborate ILs. In particular, the applicability of 11B PFG NMR for studying anions without 1H, such as [BOB]−, and the limitations of this technique to measure self-diffusion of ions in ILs are demonstrated and discussed in detail for the first time.
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| 4. |
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| 5. |
- Khan, Inayat Ali, et al.
(författare)
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Stable and Efficient PtRu Electrocatalysts Supported on Zn-BTC MOF Derived Microporous Carbon for Formic Acid Fuel Cells Application
- 2020
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Highly efficient, well-dispersed PtRu alloy nanoparticles supported on high surface area microporous carbon (MPC) electrocatalysts, are prepared and tested for formic acid oxidation reaction (FAOR). The MPC is obtained by controlled carbonization of a zincbenzenetricarboxylate metal-organic framework (Zn-BTC MOF) precursor at 950◦C, and PtRu (30 wt.%) nanoparticles (NPs) are prepared and deposited via a polyol chemical reduction method. The structural and morphological characterization of the synthesized electrocatalysts is carried out using powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), an energy dispersive X-ray (EDX) technique, and gas adsorption analysis (BET). The FAOR performance of the catalysts is investigated through cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). A correlation between high electrochemical surface area (ECSA) and high FAOR performance of the catalysts is observed. Among the materials employed, Pt1Ru2/MPC 950 with a high electrochemical surface area (25.3 m2 g −1 ) consequently showed superior activity of the FAOR (Ir = 9.50 mA cm−2 and Jm = 2,403 mA mg−1 Pt ) at room temperature, with improved tolerance and stability toward carbonaceous species. The superior electrochemical performance, and tolerance to CO-poisoning and long-term stability is attributed to the high surface area carbon support (1,455 m2 g −1 ) and high percentage loading of ruthenium (20 wt.%). The addition of Ru promotes the efficiency of electrocatalyst by offering FAOR via a bifunctional mechanism.
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| 6. |
- Laxman, Karthik, et al.
(författare)
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Disinfection of Bacteria in Water by Capacitive Deionization
- 2020
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Ingår i: Frontiers in Chemistry. - : FRONTIERS MEDIA SA. - 2296-2646. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Clean water is one of the primary UN sustainable development goals for 2,030 and sustainable water deionization and disinfection is the backbone of that goal. Capacitive deionization (CDI) is an upcoming technique for water deionization and has shown substantial promise for large scale commercialization. In this study, activated carbon cloth (ACC) electrode based CDI devices are used to study the removal of ionic contaminants in water and the effect of ion concentrations on the electrosorption and disinfection functions of the CDI device for mixed microbial communities in groundwater and a model bacterial strainEscherichia coli. Up to 75 % of microbial cells could be removed in a single pass through the CDI unit for both synthetic and groundwater, while maintaining the salt removal activity. Mortality of the microbial cells were also observed during the CDI cell regeneration and correlated with the chloride ion concentrations. The power consumption and salt removal capacity in the presence and absence of salt were mapped and shown to be as low as 0.1 kWh m(-3)and 9.5 mg g(-1), respectively. The results indicate that CDI could be a viable option for single step deionization and microbial disinfection of brackish water.
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| 7. |
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| 8. |
- Liu, Yanrong, et al.
(författare)
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Screening Deep Eutectic Solvents for CO2 Capture With COSMO-RS
- 2020
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 8:82
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Tidskriftsartikel (refereegranskat)abstract
- In this work, 502 experimental data for CO2 solubilities and 132 for Henry’s constantsof CO2 in DESs were comprehensively summarized from literatures and used for furtherverification and development of COSMO-RS. Large systematic deviations of 62.2, 59.6,63.0, and 59.1% for the logarithmic CO2 solubilities in the DESs (1:2, 1:3, 1:4, 1:5),respectively, were observed for the prediction with the original COSMO-RS, while thepredicted Henry’s constants of CO2 in the DESs (1:1.5, 1:2, 1:3, 1:4, 1:5) at temperaturesranging of 293.15–333.15 K are more accurate than the predicted CO2 solubility withthe original COSMO-RS. To improve the performance of COSMO-RS, 502 data pointsof CO2 solubility in the DESs (1:2, 1:3, 1:4, 1:5) were used for correcting COSMO-RSwith a temperature-pressure dependent parameter, and the CO2 solubility in the DES(1:6) was predicted to further verify the performance of the corrected model. The resultsindicate that the corrected COSMO-RS can significantly improve the model performancewith the ARDs decreasing down to 6.5, 4.8, 6.5, and 4.5% for the DESs (1:2, 1:3, 1:4, and 1:5), respectively, and the corrected COSMO-RS with the universal parameters can beused to predict the CO2 solubility in DESs with different mole ratios, for example, for theDES (1:6), the corrected COSMO-RS significantly improves the prediction with an ARD of10.3% that is much lower than 78.2% provided by the original COSMO-RS. Additionally,the result from COSMO-RS shows that the σ-profiles can reflect the strength of molecularinteractions between an HBA (or HBD) and CO2, determining the CO2 solubility, and thedominant interactions for CO2 capture in DESs are the H-bond and Van der Waals force,followed by the misfit based on the analysis of the predicted excess enthalpies.
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| 9. |
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| 10. |
- Naz, Sadia, et al.
(författare)
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One-Pot Deconstruction and Conversion of Lignocellulose Into Reducing Sugars by Pyridinium-Based Ionic Liquid–Metal Salt System
- 2020
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Constantly decreasing fossil resources and exceeding energy demands are the most alarming concerns now-a-days. The only way out is to develop efficient, safe and economic biomass processing protocols that can lead towards biofuels and fine chemicals. This research is one of such consequences involving the deconstruction and conversion of wheat straw carbohydrate constituents into reducing sugars via one-pot reaction promoted by Lewis acidic pyridinium based ionic liquids (PyILs) mixed with different metal salts (MCl). Various parameters such as the type of metal salt, loading amount of metal salt, time, temperature, particle size of biomass and water content which affect the deconstruction of wheat straw have been evaluated and optimized. Among the studied IL and metal salt systems, the best results were obtained with [BMPy]+CoCl3‒. The dinitrosalicylic acid (DNS) assay was used to determine the percentage of total reducing sugars (TRS) generated during treatment of wheat straw. The deconstructed wheat straw was characterized with various analytical tools i.e. FTIR, SEM and XRD analyses. The ionic liquid‒metal salt system was recycled for subsequent treatment of wheat straw. Statistical parameters were calculated from analysis of variance (ANOVA) at 0.05 level of confidence.
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