In the present study, a dense W-Mo coating was formed onto the gear steel by using double-glow plasma surface alloying technique. The nanoindentation test was used to measure the hardness and ...elasticity modulus of the coating. The scratch test was applied to evaluate the critical load for coating delamination, which measured the adhesion strength of the coating. The tribological behavior of the W-Mo coating was estimated using a pin-on-disc tribometer by rubbing against the Si3N4 ceramic ball. Results showed that the W-Mo coating was well diffusely bonded to the substrate. In terms of the H/E and H3/E2 ratios, the coated sample was nearly two times greater than that of the uncoated sample. The specific wear rates of the W-Mo coating at room and high temperature were 8.1×10−5 mm3N−1m−1 and 11.2×10−5 mm3N−1m−1 respectively, about only 19% of that of the uncoated sample. The excellent wear resistance of the W-Mo coating may be due to its high resistance to plastic deformation and good load bearing capacity.
•The W-Mo coating was formed on the gear steel by double-glow plasma surface alloying technique.•The hardness (H), elastic modulus (E) and adhesion strength of coating were discussed.•The W-Mo coating produced by DG Technique has contributed to better tribological properties both at room and high temperature.
Previous association studies examining the relationship between the APOC1 polymorphism and susceptibility to Alzheimer's disease (AD) have shown conflicting results, and it is not clear if an APOC1 ...variant acts as a genetic risk factor in AD etiology across multiple populations.
To confirm the risk association between APOC1 and AD, we designed a case-control study and also performed a meta-analysis of previously published studies.
Seventy-nine patients with AD and one hundred fifty-six unrelated controls were included in case-control study. No association was found between the variation of APOC1 and AD in stage 1 of our study. However, our meta-analysis pooled a total of 2092 AD patients and 2685 controls. The APOC1 rs11568822 polymorphism was associated with increased AD risk in Caucasians, Asians and Caribbean Hispanics, but not in African Americans. APOE ε4 carriers harboring the APOC1 insertion allele, were more prevalent in AD patients than controls (χ(2) = 119.46, OR = 2.79, 95% CI = 2.31-3.36, P<0.01).
The APOC1 insertion allele, in combination with APOE ε4, likely serves as a potential risk factor for developing AD.
Five alkaloids, including two previously undescribed alkaloids, named forsyshiyanines A and B, attributable to the rare skeletons 4b,5,6,7,8,8a,9,10-octahydrobenzofquinoline and ...(6,7-dihydro-5H-cyclopentacpyridin-7-yl)methyl, respectively, along with three known ones (3–5), were isolated from the ripe fruits of Forsythia suspensa. The chemical structures including absolute configurations of two undescribed compounds were established using integrated spectroscopic techniques, electronic circular dichroism calculations, and single-crystal x-ray diffraction analysis. In vitro, five alkaloids showed anti-inflammatory activities, with the inhibition rates of the release of β-glucuronidase from polymorphonuclear leukocytes of rats being in the range 47.9%–56.0% at a concentration of 10 μM. Moreover, five compounds exhibited anti-viral activities against influenza A virus and respiratory syncytial virus, with IC50 values in the range of 7.3–32.5 μM and EC50 values in the range 3.7–14.1 μM.
The fruit of Forsythia suspensa is a traditional Chinese medicine with good anti-inflammatory and anti-viral activities. Display omitted
•Two undescribed alkaloids were isolated from the fruits of Forsythia suspensa.•The absolute configurations of two undescribed alkaloids were determined.•Five alkaloids showed significant anti-inflammatory activities.•Five alkaloids showed anti-viral activities against the H1N1 virus and RSV.
To construct structurally stable sulfur cathode of Li-S battery with improved cycling performance, poly(acrylic acid) (PAA) crosslinked by cationic hydroxypropyl polyrotaxane (HPRN
+
)
via
...dynamically reversible boronic ester bonds is synthesized and serves as the cathode binder. The smart polymer networks offer multifunction including buffering the volume change of the cathode during charge/discharge through the pulley effect of polyrotaxanes (PR), suppressing the shuttle effect by adsorption of polysulfide using the plentiful carboxyl, hydroxyl and quaternary ammonium cationic groups, and self-healing the micro-damages to ensure stable conduction pathways of the electrode. As a result, the Li-S batteries based on this novel multifunctional binder and simple commercial sulfur/carbon composites cathode exhibit excellent specific capacity and cycling stability. In particular, the specific capacity decay per cycle of the cell is only 0.064% along with high Coulombic efficiency after 550 cycles at 1.0 C, which is superior to most of the reported binders. Even under high sulfur loading, moreover, the cathode can deliver superior areal capacity and cycling stability. This proposed binder provides a new way for the design of high-stability sulfur cathodes.
► A chromising coating was prepared on titanium alloys by plasma alloying technology. ► The isothermal oxidation of the chromising coating was studied at 650–850°C. ► The Ti–Cr mutual diffusion layer ...of chromsing coating prevented the intrusion of O. ► A multi-layer structure with Cr2O3, TiO2, and Al2O3 was formed during oxidation. ► Ti, Al, and Cr diffused predominantly outward during oxidation.
Double-glow plasma surface chromising was performed on TC4 (Ti–6Al–4V) alloys, and the isothermal oxidation behaviour of TC4 was investigated at 650, 750, and 850°C. The surface treatment caused the formation of a Ti–Cr mutual diffusion layer beneath the alloy surface. The chromising coating consisted of Cr, Cr1.97Ti1.07, and CrTi4. During oxidation, Cr, Ti, and Al diffused outward to form multi-layer oxide films, which prevented the diffusion of oxygen.
In this study, a series of proline ionic liquids with different lengths of hydrophobic alkyl on the side chain were used to modify the
Candida Antarctic
lipase B (CALB). The catalytic activity, ...thermal stability and tolerance to methanol and DMSO of the modified enzyme were all improved simultaneously. The optimum temperature changed from 55 to 60 ℃. The hydrophobicity and anion type of the modifier have important influence on the catalytic performance of CALB. CALB modified by ProC
12
H
2
PO
4
has a better effect. Under the optimal conditions, its hydrolysis activity was 3.0 times than that of the native enzyme, the catalytic efficiency Kcat/Km improved 2.8 times in aqueous phase, and the tolerance to organic solvent with strong polarity (50% methanol 2 h) was increased by 6.8 times. Fluorescence spectra and circular dichroism (CD) spectroscopy showed that the introduction of ionic liquids changed the microenvironment near the fluorophores of the enzyme protein, the α-helix decreased and β-sheet increased in the secondary structure of the modified enzymes. The root mean square deviation (RMSD), residue root mean square fluctuation (RMSF), radius of gyration (Rg), and solution accessible surface area (SASA) of ProC
2
Br-CALB, ProC
12
Br-CALB and native CALB were obtained for comparison by molecular dynamics simulation. The results of dynamics simulation were in good agreement with enzymology experiment. The introduction of ionic liquids can keep CALB in a better active conformation, and proline ionic liquids with long hydrophobic chains can significantly improve the surface hydrophobicity and overall rigidity of CALB. This research offers a new idea for rapid screening of efficient modifiers and provision of enzymes with high stability and activity for industrial application.
Various betaine ionic liquids composed of different chain lengths and different anions were designed and synthesized to modify
lipase B (CALB). The results showed that the catalytic activity of all ...modified lipases improved under different temperature and pH conditions, while also exhibiting enhanced thermostability and tolerance to organic solvents. With an increase in ionic liquid chain length, the modification effect was greater. Overall, CALB modified by BetaineC
H
PO
performed best, with the modified CALB enzyme activity increased 3-fold, thermal stability increased 1.5-fold when stored at 70°C for 30 min, with tolerance increased 2.9-fold in 50% DMSO and 2.3-fold in 30% mercaptoethanol. Fluorescence and circular dichroism (CD) spectroscopic analysis showed that the introduction of an ionic liquid caused changes in the microenvironment surrounding some fluorescent groups and the secondary structure of the CALB enzyme protein. In order to establish the enzyme activity and stability change mechanisms of the modified CALB, the structures of CALB modified with BetaineC
Cl and BetaineC
Cl were constructed, while the reaction mechanisms were studied by molecular dynamics simulations. Results showed that the root mean square deviation (RMSD) and total energy of modified CALB were less than those of native CALB, indicating that modified CALB has a more stable structure. Root mean square fluctuation (RMSF) calculations showed that the rigidity of modified CALB was enhanced. Solvent accessibility area (SASA) calculations exhibited that both the hydrophilicity and hydrophobicity of the modified enzyme-proteins were improved. The increase in radial distribution function (RDF) of water molecules confirmed that the number of water molecules around the active sites also increased. Therefore, modified CALB has enhanced structural stability and higher hydrolytic activity.
γ-aminobutyric acid (GABA) is a four-carbon non-protein amino acid presented in a wide range of organisms. In this study, a suppression subtractive hybridization (SSH) library was constructed using ...roots of a legume shrub, Caragana intermedia, with the combined treatment of 300 m m NaCl and 300 m m NaCl + 10 m m GABA. We obtained 224 GABA-regulated unique expressed sequence tags (ESTs) including signal transduction, transcriptional regulation, hormone biosynthesis, reactive oxygen species (ROS) and polyamine metabolism, etc. The key H₂O₂-generated genes, NADPH oxidase (CaGR60), peroxidase (CaGR61) and amine oxidase (CaGR62), were regulated at the mRNA level by 10 m m GABA, which clearly inhibited H₂O₂ accumulation brought about by NaCl stress in roots and leaves with the observation of 3,3′-diaminobenzidine (DAB) staining. Similarly, 10 m m GABA also regulated the expression of 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO) genes (CaGR30 and CaGR31) and ethylene production in NaCl-treated roots. Surprisingly, these H₂O₂-generated genes were enhanced at the mRNA level by a lower concentration of GABA, at 0.25 m m, but not other alternative nitrogen sources, and endogenous GABA accumulated largely just by the application of GABA at either concentration. Our results further proved that GABA, as a signal molecule, participates in regulating the expression of genes in plants under salt stress.
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