| 1. |
- An, Rong, et al.
(författare)
-
Ionic liquids on uncharged and charged surfaces: In situ microstructures and nanofriction
- 2022
-
Ingår i: Friction. - : Springer. - 2223-7690 .- 2223-7704. ; 10:11, s. 1893-1912
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 2. |
- He, Niling, et al.
(författare)
-
Simultaneous and rate-coordinated conversion of lignocellulose derived glucose, xylose, arabinose, mannose, and galactose into D-lactic acid production facilitates D-lactide synthesis
- 2023
-
Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524. ; 377
-
Tidskriftsartikel (refereegranskat)abstract
- D-lactide is the precursor of poly(D-lactide) (PDLA) or stereo-complex with poly(L-lactide) (PLLA). Lignocellulosic biomass provides the essential feedstock option to synthesize D-lactic acid and D-lactide. The residual sugars in D-lactic acid fermentation broth significantly blocks the D-lactide synthesis. This study showed a simultaneous and rate-coordinated conversion of lignocellulose derived glucose, xylose, arabinose, mannose, and galactose into D-lactic acid by adaptively evolved Pediococcus acidilactici ZY271 by simultaneous saccharification and co-fermentation (SSCF) of wheat straw. The produced D-lactic acid achieved minimum residual sugars (∼1.7 g/L), high chirality (∼99.1%) and high titer (∼128 g/L). A dry acid pretreatment eliminated the wastewater stream generation and the biodetoxification by fungus Amorphotheca resinae ZN1 removed the inhibitors from the pretreatment. The removal of the sugar residues and inhibitor impurities in D-lactic acid production from lignocellulose strongly facilitated the D-lactide synthesis. This study filled the gap in cellulosic D-lactide production from lignocellulose-derived D-lactic acid.
|
|
| 3. |
|
|
| 4. |
- Knowles, Joshua W., et al.
(författare)
-
Identification and validation of N-acetyltransferase 2 as an insulin sensitivity gene
- 2015
-
Ingår i: Journal of Clinical Investigation. - 0021-9738 .- 1558-8238. ; 125:4, s. 1739-1751
-
Tidskriftsartikel (refereegranskat)abstract
- Decreased insulin sensitivity, also referred to as insulin resistance (IR), is a fundamental abnormality in patients with type 2 diabetes and a risk factor for cardiovascular disease. While IR predisposition is heritable, the genetic basis remains largely unknown. The GENEticS of Insulin Sensitivity consortium conducted a genome-wide association study (GWAS) for direct measures of insulin sensitivity, such as euglycemic clamp or insulin suppression test, in 2,764 European individuals, with replication in an additional 2,860 individuals. The presence of a nonsynonymous variant of N-acetyltransferase 2 (NAT2) [rs1208 (803A>G, K268R)] was strongly associated with decreased insulin sensitivity that was independent of BMI. The rs1208 "A" allele was nominally associated with IR-related traits, including increased fasting glucose, hemoglobin A1C, total and LDL cholesterol, triglycerides, and coronary artery disease. NAT2 acetylates arylamine and hydrazine drugs and carcinogens, but predicted acetylator NAT2 phenotypes were not associated with insulin sensitivity. In a murine adipocyte cell line, silencing of NAT2 ortholog Nat1 decreased insulin-mediated glucose uptake, increased basal and isoproterenol-stimulated lipolysis, and decreased adipocyte differentiation, while Nat1 overexpression produced opposite effects. Nat1-deficient mice had elevations in fasting blood glucose, insulin, and triglycerides and decreased insulin sensitivity, as measured by glucose and insulin tolerance tests, with intermediate effects in Nat1 heterozygote mice. Our results support a role for NAT2 in insulin sensitivity.
|
|
| 5. |
- Li, Jimei, et al.
(författare)
-
Expression of heparanase in vascular cells and astrocytes of the mouse brain after focal cerebral ischemia
- 2012
-
Ingår i: Brain Research. - : Elsevier BV. - 0006-8993 .- 1872-6240. ; 1433, s. 137-144
-
Tidskriftsartikel (refereegranskat)abstract
- Heparanase is a heparan sulfate degrading endoglycosidase. Previous work has demonstrated that heparanase plays important roles in various biological processes including angiogenesis, wound healing and metastasis. However, the role of heparanase in the post-ischemic brain is not well defined. Transient focal cerebral ischemia in adult mice was induced by ligations of the right middle cerebral artery (MCA) and both common carotid arteries (CCAs). All mice were subjected to bromodeoxyuridine (BrdU) injection and sacrificed at different time points after stroke for immunohistochemical and Western blot analyses. Heparanase expression increased after ischemia in both cell-specific and time-dependent manners. Three to 7 days after stroke, levels of the 50-kD heparanase, basic fibroblast growth factor (FGF-2), and angiopoietin-2 (Ang-2) increased in the peri-infarct region. At early time points, heparanase expression was largely confined to proliferating vascular endothelial cells. At 14 days after ischemia, this expression had shifted to astrocytes in the same region. These data show that cerebral ischemia markedly increases heparanase levels in endothelial cells and then in astrocytes. The unique features of the heparanase upregulation imply that heparanase may play specific roles in the pathological and regenerative processes during the acute and sub-acute/chronic phases in the post-stroke brain.
|
|
| 6. |
- Oris, Chansa, et al.
(författare)
-
Forms of potassium and chlorine from oxy-fuel co-combustion of lignite coal and corn stover
- 2019
-
Ingår i: Carbon Resources Conversion. - : Elsevier BV. - 2588-9133. ; 2:2, s. 103-110
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, the forms of potassium and chlorine from oxy-fuel co-combustion of lignite coal and corn stover under atmospheric pressure were investigated. In order to check transitional stage, the feedstocks were combusted stepwise, first by pyrolysis to form coke under N2 environment and later by coke combustion into the ash at 850 °C in O2/CO2 atmosphere. The results show that an increase in blend ratio from 15% to 40% results in an increase in water-soluble potassium in the feedstock and the ashes from 0.15% to 0.4% and 0.015% to 0.038 % in weight respectively. The water-soluble potassium is present mainly as KCl and K2SO4. For ammonium acetate soluble potassium, a similar trend to water-soluble potassium is presented but with a much lower content of potassium. The bound potassium in the fuel matrix exists, likely in the form of AlKSi2O6. Chlorides are present mainly in the form of KCl which is the dominant water-soluble compound.
|
|
| 7. |
- Qin, Yao, et al.
(författare)
-
Molecular insights into the microstructure of ethanol/water binary mixtures confined within typical 2D nanoslits : The role of the adsorbed layers induced by different solid surfaces
- 2020
-
Ingår i: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 509
-
Tidskriftsartikel (refereegranskat)abstract
- With the emergence of membrane separation and heterogeneous catalysis applications that are associated with confined ethanol/water binary mixture in the pores of two-dimensional (2D) nanomaterials, understanding their confined microstructures is the first step for further relevant applications. In this work, molecular dynamics was performed to investigate the microstructure of ethanol/water binary mixture of 5% mole fraction confined within the four typical 2-nm width 2D-nanoslits (i.e. hBN, GO-0.2, GO-0.4 and Ti3C2(OH)2). Results demonstrated that different chemical properties of solid surfaces can induce distinctive microstructures of mixed fluid within the interfacial contact (adsorbed) layer and thus can result in different mobility of water molecules within the subcontact layer. The residence times of water molecules in the subcontact layer were found in the sequence of Ti3C2(OH)2 > hBN > GO-0.4 > GO-0.2, whereas their sequence of diffusion coefficient within the x-z plane was Ti3C2(OH)2 > hBN > GO-0.2 > GO-0.4. Detailed hydrogen bond (HB) microstructure analysis showed that a high average number of HBs (between fluid molecules of the interfacial contact layer and water molecules of the subcontact layer) induced by solid surfaces could facilitate water molecules to reside in the subcontact layer. Moreover, the small average number of HBs between the water molecules themselves in the subcontact layer could lead to high in-plane diffusion coefficients.
|
|
| 8. |
- Wang, Tiantian, et al.
(författare)
-
Microstructural probing of phosphonium-based ionic liquids on a gold electrode using colloid probe AFM
- 2022
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 24:41, s. 25411-25419
-
Tidskriftsartikel (refereegranskat)abstract
- Atomic force microscopy (AFM) with a gold colloid probe modeled as the electrode surface is employed to directly capture the contact resonance frequency of two phosphonium-based ionic liquids (ILs) containing a common anion [BScB]− and differently lengthened cations ([P6,6,6,14]+ and [P4,4,4,8]+). The comparative interfacial studies are performed by creating IL films on the surface of gold, followed by measuring the wettability, thickness of the films, adhesion forces, surface morphology and AFM-probed contact resonance frequency. In addition, the cyclic voltammetry and impedance spectroscopy measurements of the neat ILs are measured on the surface of the gold electrode. The IL with longer cation alkyl chains exhibits a well-defined thin film on the electrode surface and enhanced the capacitance than the shorter chain IL. The AFM contact resonance frequency and force curves reveal that the longer IL prefers to form stiffer ion layers at the gold electrode surface, suggesting the “…anion–anion–cation–cation…” bilayer structure, in contrast, the shorter-chain IL forms the softer cation–anion alternating structure, i.e., “…anion–cation–anion–cation…”.
|
|
