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With the merits of high surface area and plentiful metal sites, metal–organic frameworks (MOFs) are promising catalysts for the hydrogen evolution reaction (HER). However, the HER activity of MOFs is not satisfactory due to their poor electrical conductivity and fewer HER active sites. Herein, taking a nickel-terephthalic acid-based MOF (Ni MOF) as an example, a low-temperature, environmentally friendly, and time-efficient N2/H2 plasma activation strategy is developed to implant multiple HER active species (Ni, Ni3N and MoNi4) in molybdenum-based polyoxometalate (POM)-encapsulated Ni MOF nanosheet arrays (Ni MOF/POM). Endowed with enhanced conductivity and increased active sites, the plasma-activated Ni MOF/POM (P-Ni MOF/POM) exhibits a splendid HER activity (35 mV at 10 mA cm−2) and a long stability (up to 120 h) in alkaline solution. Excellent HER performance is also demonstrated by P-Ni MOF/POM in alkaline seawater. During the HER process, it is interesting to observe that the Ni MOF in P-Ni MOF/POM undergoes reconstruction into β-Ni(OH)2, while the HER active species (Ni, Ni3N and MoNi4) are largely maintained. The dynamic contact angle, in situ electrochemical impedance spectroscopy (EIS), and kinetic isotope effect (KIE) characterization studies suggest that plasma activation plays an important role in enhancing water adsorption and accelerating the kinetics of water dissociation, thus ensuring enhanced HER activity. [ABSTRACT FROM AUTHOR]

We propose a new method for measuring the refractive index of liquids with high precision; the method is based on use of the optical fiber end face. As an example, we investigated the refractive index of sugar solution under varying conditions tens of times. The results show that this method has the advantage of higher stability and repeatability. The concentration and the temperature-dependent refractive index of the sugar solution is also experimentally studied. OCIS codes: 120.5710, 120.5700, 120.4640.

The alkaline hydrogen evolution reaction (HER) activity of layered metal hydroxides is not satisfactory due to their poor electrical conductivity and limited active sites. Taking Ni(OH)2 as a typical example, density functional theory (DFT) calculations are first performed to confirm that the phase engineering of Ni(OH)2 (α-Ni(OH)2 and β-Ni(OH)2) can effectively optimize hydrogen adsorption, with β-Ni(OH)2 showing better HER activity. It is also predicted that the electrical conductivity and Volmer step in the HER can be efficiently improved when loading Ni nanoparticles on the surface of Ni(OH)2. Based on DFT calculations, heterostructured Ni/α-Ni(OH)2 and Ni/β-Ni(OH)2 nanosheet arrays (NSAs) are experimentally constructed. Compared to Ni/α-Ni(OH)2 NSAs, the Ni/β-Ni(OH)2 NSAs exhibit enhanced HER activity with a small overpotential of 58 mV and 62 mV to achieve 10 mA cm−2 in alkaline solution and alkaline seawater, respectively. Moreover, the Ni/β-Ni(OH)2 NSAs also manifest better hydrazine oxidation reaction activity than Ni/α-Ni(OH)2 NSAs. Impressively, when Ni/β-Ni(OH)2 NSAs are applied as a bi-functional electrocatalyst for hydrazine-assisted water splitting, only a small voltage of 0.16 V/0.24 V is needed to deliver 10 mA cm−2 in alkaline solution/alkaline seawater. [ABSTRACT FROM AUTHOR]

Hepatitis B virus(HBV) infection remains a global problem, despite the effectiveness of the Hepatitis B vaccine in preventing infection. The resolution of Hepatitis B virus infection has been believed to be attributable to virus-specific immunity. In vivo direct evaluation of anti-HBV immunity in the liver is currently not possible. We have developed a new assay system that detects HBV clearance in the liver after the hydrodynamic transfer of a reporter gene and over-length, linear HBV DNA into hepatocytes, followed by bioluminescence imaging of the reporter gene (Fluc). We employed bioluminescence detection of luciferase expression in HBV-infected hepatocytes to measure the Hepatitis B core antigen (HBcAg)-specific immune responses directed against these infected hepatocytes. Only HBcAg-immunized, but not mock-treated, animals decreased the amounts of luciferase expression, HBsAg and viral DNA from the liver at day 28 after hydrodynamic infection with over-length HBV DNA, indicating that control of luciferase expression correlates with viral clearance from infected hepatocytes.

Objective: To optimize the technical parameters related to the preparation of novel frozen human platelets and formulate corresponding protocol for its preparation., Methods: Novel frozen human platelets were prepared with O-type bagged platelet-rich plasma (PRP), the key technical parameters (DMSO addition, incubation time, centrifugation conditions, etc.) of the preparation process were optimized, and the quality of the frozen platelets was evaluated by routine blood tests, apoptosis rate, platelet activation rate and surface protein expression level., Results: In the preparation protocol of novel frozen human platelets, the operation of centrifugation to remove supernatant was adjusted to before the procedure of platelets freezing, and the effect of centrifugation on platelets was minimal when the centrifugation condition was 800× g for 8 min. In addition, platelets incubated with DMSO for 30 min before centrifugation exhibited better quality after freezing and thawing. The indexes of novel frozen human platelets prepared with this protocol remained stable after long-term cryopreservation., Conclusion: The preparation technique of novel frozen human platelets was established and the protocol was formulated. It was also confirmed that the quality of frozen platelets could be improved by incubating platelets with DMSO for 30 min and then centrifuging them at 800× g for 8 min in the preparation of novel frozen human platelets.

Objective: To optimize the single centrifugation preparation protocol of rat platelet-rich plasma (PRP)., Methods: The arterial blood of rats obtained by carotid artery intubation was collected by heparin sodium anticoagulant tubes, and then the blood divided into sterile EP tubes, adjusting the red blood cell concentration with normal saline, while rat PRP was prepared by centrifugation under different conditions (the centrifugal force was 200× g -240× g , and the centrifugal time was 8-12 min). Subsequently, the blood cell count and quality evaluation of anticoagulat whole blood and PRP were performed by hematology analyzer and flow cytometry, respectively, and the differences between different groups were compared., Results: The red blood cell concentration to (5.5-6.5)×10 12 /L after anticoagulation of rat whole blood was good for PRP extraction. When the blood samples was centrifuged at 220× g for 10 min, the platelet recovery rate was the highest［(53.52±0.63)%］. The level of apoptosis and activation of plateles in PRP were not significantly different compared to whole blood( P >0.05), and the release level of growth factor was significantly increased( P <0.05)., Conclusion: It is a key to improve the PRP extraction efficiency by reducing the amount of mixed red blood cell, and this study successfully modified the preparation method of rat PRP, with platelets high recovery rate and stable quality.

Objective: To analyze the preservation effect and related influencing factors of human peripheral blood mononuclear cells under serum-free condition at 4 ℃., Methods: Human peripheral blood mononuclear cells were isolated by density gradient centrifugation, and stored at 4 ℃ under different cell concentrations, supplemented with human serum albumin, and glucose. The cell viability, total cell number, viable cell number and cell phenotype were detected during preservation of 72 h., Results: With the prolongation of storage time, the number of human peripheral blood mononuclear cells gradually decreased( r =0.982). Compared with the cell concentration of (5-6)×10 6 cells/ml, the cell number decreased more slowly when the cell storage concentration was (1-2)×10 6 cells/ml; Adding human serum albumin and glucose can effectively improve the survival rate of human peripheral blood mononuclear cells, among which 2% human serum albumin has a better preservation effect; Compared with the blank control group, the analysis results of cell subsets showed that the downward trends of NK cells and T cells were significantly slowed after adding albumin and glucose., Conclusion: The cell density of (1-2)×10 6 /ml and 2% human serum albumin are more suitable for the preservation of PBMC, and 5% glucose can improve the preservation effect of human peripheral blood mononuclear cells at 4 ℃.