The suppression of dark current for achieving high-performance Ga2O3 nanorod array ultraviolet photodetector

Gallium oxide (Ga₂O₃) is a promising candidate for next-generation solar-blind photodetectors (PDs) because of its large bandgap of 4.9 eV. Its single-crystal nanorod structure improves its photoelectric performance, which promotes carrier transformation and separation. However, Ga₂O₃ nanorods fabricated by the hydrothermal method have many oxygen vacancies, which largely enhance the dark current and reduce the on/off ratio of PDs, restricting application of such devices. Therefore, in this paper, dual strategies are applied to reduce the dark current of a metal–semiconductor–metal-structured Ga₂O₃ nanorod PD fabricated by the hydrothermal method. Through these dual strategies, which include annealing treatment and the application of a polymethyl methacrylate (PMMA) coating, the dark current of the PD is reduced from 1.34 × 10^?7 to 2.04 × 10^?9 A at 1 V, resulting in the on/off ratio of the PD reaching as high as 3.24 × 10⁴. Besides, the responsivity and detectivity of the device reach 1.73 A/W and 2.53 × 10¹² Jones respectively, which represents better performance than those of other reported Ga₂O₃ nanorod array PDs. Results have shown that the new strategy adopted can greatly improve the performance of Ga₂O₃-based ultraviolet photodetectors.     

Ablation behavior of thin-blade co-deposited C/Cx-SiCy composites under the influence of the complex fluid conditions of the oxyacetylene torch

This paper offers a new way of testing the ablation property of material under an oxyacetylene torch using a thin-blade specimen, which costs much less time to reach the maximum temperature and provides a harsh turbulence fluid field that's closer to reality. The thin-blade specimen experiences a higher turbulent intensity than the traditional disk-like specimen, leading to more efficient heat exchange. The fluid field simulation agrees with the testing results. In addition, we manage to synthesize the C/Cx-SiCy composites with the co-deposition chemical vapor infiltration (CVI) method. The C/Cx-SiCy composites exhibit a similar anti-ablation property as C/C composites and consist of enough SiC phase simultaneously, combining the advantages of both C/C composites and C/SiC composites. The thin-blade C/Cx-SiCy composites show a lower linear ablation rate (1.6 μm/s) than C/C composites (4.1 μm/s) and C/SiC composites (19.6 μm/s) during the oxyacetylene test. The glass layer formed on the surface of C/Cx-SiCy could cling to the bulk material instead of peeling off due to the high PyC content in the matrix could protect the SiO₂ from blowing away.     

Measurement of residual stresses in dissimilar friction stir-welded aluminium and copper plates using the contour method

The longitudinal residual stresses in the friction stir-welded plates of 5A06 aluminium and pure copper were determined using the contour method. The results revealed the presence of high tensile and compressive residual stresses on the aluminium and copper sides, respectively. The residual stresses were detected on the weld zone as well as the thermo-mechanically affected zone (TMAZ) of the aluminium plate. In contrast, the compressive residual stresses in the copper plate had a much narrower width along the weld line. Peak tensile stresses up to 240?MPa were found in the TMAZ of the aluminium plate.     

Elemental analysis of cemented carbides by calibration-free portable laser-induced breakdown spectroscopy

The process of cemented carbides manufacturing requires rapid and field elemental analytical techniques to control and evaluate the properties of products. Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is such a potential elemental analytical technique. In this work, a portable LIBS instrument combined with a CF method was developed for the analysis of cemented carbides. Three batches of cemented compact carbides without reference samples were analyzed. Qualitative and quantitative analysis of the samples were achieved by using the portable LIBS instrument combined with CF method. To validate the analysis results, X-ray fluorescence spectrometry (XRF) was used to analyze the samples as well. The results of CF-LIBS agreed well with the results of XRF, with relative errors between ?29.53 and 24.70%. The results demonstrated that the portable LIBS instrument combined with CF method was capable for direct and rapid analysis without any need of standard measurements. Notably, with the portable LIBS instrument combined with CF method, acceptable accuracy could be obtained, which is promising for practical field applications.     

Characterisation of the Dynamic Interactions between Complex N-Glycans and Human CD22

CD22 (Siglec-2) is a B-cell surface inhibitory protein capable of selectively recognising sialylated glycans, thus dampening autoimmune responses against self-antigens. Here we have characterised the dynamic recognition of complex-type N-glycans by human CD22 by means of orthogonal approaches including NMR spectroscopy, computational methods and biophysical assays. We provide new molecular insights into the binding mode of sialoglycans in complex with h-CD22, highlighting the role of the sialic acid galactose moieties in the recognition process, elucidating the conformational behaviour of complex-type N-glycans bound to Siglec-2 and dissecting the formation of CD22 homo-oligomers on the B-cell surface. Our results could enable the development of additional therapeutics capable of modulating the activity of h-CD22 in autoimmune diseases and malignancies derived from B-cells.     

卡尔费休法测定液态氯乙烯中水含量的研究

采用卡尔费休法测定了液态氯乙烯单体中的水含量。试验确定了采样工具、样品的预处理方式及选用溶剂的最优方案,并进行了精密度与准确度的验证。结果表明卡尔费休法测定液态氯乙烯单体中的水含量准确、快速,可以用来准确、及时地指导生产。     

New 1,3,4-Oxadiazole Derivatives of Pyridothiazine-1,1-Dioxide with Anti-Inflammatory Activity

Numerous studies have confirmed the coexistence of oxidative stress and inflammatory processes. Long-term inflammation and oxidative stress may significantly affect the initiation of the neoplastic transformation process. Here, we describe the synthesis of a new series of Mannich base-type hybrid compounds containing an arylpiperazine residue, 1,3,4-oxadiazole ring, and pyridothiazine-1,1-dioxide core. The synthesis was carried out with the hope that the hybridization of different pharmacophoric molecules would result in a synergistic effect on their anti-inflammatory activity, especially the ability to inhibit cyclooxygenase. The obtained compounds were investigated in terms of their potencies to inhibit cyclooxygenase COX-1 and COX-2 enzymes with the use of the colorimetric inhibitor screening assay. Their antioxidant and cytotoxic effect on normal human dermal fibroblasts (NHDF) was also studied. Strong COX-2 inhibitory activity was observed after the use of TG6 and, especially, TG4. The TG11 compound, as well as reference meloxicam, turned out to be a preferential COX-2 inhibitor. TG12 was, in turn, a non-selective COX inhibitor. A molecular docking study was performed to understand the binding interaction of compounds at the active site of cyclooxygenases.     

Studies on spinel cobaltites,MCo2O4 (M = Mn,Zn, Fe,Ni and Co) and their functional properties

Optimization of electrodes for charge storage with appropriate processing conditions places significant challenges in the developments for high performance charge storage devices. In this article, metal cobaltite spinels of formula MCo₂O₄ (where M = Mn, Zn, Fe, Ni and Co) are synthesized by oxalate decomposition method followed by calcination at three typical temperatures, viz. 350, 550, and 750 °C and examined their performance variation when used as anodes in lithium ion batteries. Phase and structure of the materials are studied by powder x-ray diffraction (XRD) technique. Single phase MnCo2O4,ZnCo2O4 and Co3O4 are obtained for all different temperatures 350 °C, 550 °C and 750 °C; whereas FeCo₂O₄ and NiCo₂O₄ contained their constituent binary phases even after repeated calcination. Morphologies of the materials are studied via scanning electron microscopy (SEM): needle-shaped particles of MnCo₂O₄ and ZnCo₂O₄, submicron sized particles of FeCo₂O₄ and agglomerated submicron particle of NiCo₂O₄ are observed. Galvanostatic cycling has been conducted in the voltage range 0.005–3.0 V vs. Li at a current density of 60 mA g^?1 up to 50 cycles to study their Li storage capabilities. Highest observed charge capacities are: MnCo₂O₄ – 365 mA h g^?1 (750 °C); ZnCo₂O₄ – 516 mA h g^?1 (550 °C); FeCo₂O₄ – 480 mA h g^?1 (550 °C); NiCo₂O₄ – 384 mA h g^?1 (750 °C); and Co₃O₄ – 675 mA h g^?1 (350 °C). The Co₃O₄ showed the highest reversible capacity of 675 mA h g^?1; the NiO present in NiCo₂O₄ acts as a buffer layer that results in improved cycling stability; the ZnCo₂O₄ with long needle-like shows good cycling stability.     

高效可撤销的身份基在线离线加密方案

身份基加密（IBE）需要提供一种有效的成员撤销机制，然而，现有可撤销成员的IBE方案存在密钥更新和加密运算量过大的问题，可能使执行该操作的设备成为系统的瓶颈。将完全子树方法和在线离线技术相结合，通过修改指数逆类型IBE的密钥生成和加密算法，提出了一种高效可撤销的身份基在线离线加密方案。方案利用完全子树方法生成更新钥，使得撤销用户无法获得更新钥，进而失去解密能力；利用在线离线技术，将大部分加密运算在离线阶段进行预处理，使得在线阶段仅执行少量简单计算即可生成密文。与相关知名方案相比，该方案不仅提高密钥生成中心的密钥更新的效率，而且极大减少了轻量级设备的在线加密工作量，适合于轻量级设备保护用户隐私信息。