Combating the Tribo-Corrosion of LDX2404 Lean Duplex Stainless Steel by Low Temperature Plasma Nitriding

A lean duplex stainless steel, LDX2404, was DC plasma nitrided under a range of treatment conditions. The microstructure characterisation evaluation of the treated samples revealed that a dense, super-hard surface layer can be produced by low-temperature (<450 °C) plasma treatments. The original austenite phase became S-phase and the ferrite phase was supersaturated with nitrogen and ε-Fe3N nitride precipitated from it. When plasma nitriding was carried out at above 450 °C, chromium nitrides precipitated in the surface nitrided layer. Compared to the untreated samples, the surface hardness of the lean duplex stainless steel (DSS) is increased up to four times. The dry wear resistance increased when increasing the treatment temperature. In contrast, the low-temperature treated samples showed the best performance in the electrochemical corrosion and corrosion-wear tests; the performance of the high temperature (>450 °C) plasma nitrided samples was found to be significantly worse than that of the untreated material

Evaluation of Reactivity of Monoclonal Antibodies Against Omp25 of Brucella spp.

Brucellosis is a serious zoonosis occurring mainly in developing countries, and its diagnosis is largely dependent on serologic detection and bacterial culture. In this study, we developed the murine monoclonal antibodies (mAbs) against a conserved and major outer membrane protein 25 (Omp25) of Brucella species (B. spp.) for use in clinical diagnosis. The mAbs to Omp25 were produced by hybridoma technique, which were utilized for developing various immunoassays for detection of Brucellae, including Western blot (WB), enzyme-linked immunosorbent assay (ELISA), immunochemical staining (ICS), immunofluorescence staining (IFS), and flow cytometry assay (FCM). A number of five mAbs (2B10, 4A12, 4F10, 6C12, and 8F3) specific to Omp25 were selected, including 2 IgG1, 2 IgG2a, and 1 IgG2b. Among them, mAbs 6C12, 8F3, and 4A12 reacted highly with B. melitensis (M5-90), B. abortus (S19, 104M, and 2308), and B. suis strain (S2). No cross-reactivity with Yersinia enterocolitica O:9, Salmonella spp., and Escherichia coli was found. By mapping Omp25 epitopes, mAb 6C12 was found as reacting with a semi-conformational epitope, and mAbs 4A12 and 8F3 as recognizing a different linear epitope, respectively. The paired mAbs were tested for detecting Brucella species, suggesting that 8F3 was suitable for solid phase capture and 6C12 or 4A12 was suitable for conjugation with HRP for detection of Brucella Omp25 in ELISA. The FCM was established by mAb 6C12 for detecting intracellular Brucellae-infected peripheral blood mononuclear cells (PBMCs) from brucellosis patients. In conclusion, mAbs against Omp25 are precious reagents for detection of Brucellae in clinical samples with various immunoassays. mAb 6C12-based FCM could be potentially used for the monitoring of therapeutic efficacy for brucellosis in clinical practice

Structure-Activity Relationship Study Enables the Discovery of a Novel Berberine Analogue as RXRα Activator to Inhibit Colon Cancer

黄连素是从黄连、黄柏等传统中药中提取的单体化合物，常用于治疗痢疾及其它消化道感染。近年来，黄连素的抗心律失常、调控能量代谢、降血糖血脂和抗癌等多重功效使其成为一个“明星”中药单体化合物。尽管黄连素具有很好的安全性，但其抗癌作用在临床应用上仍具有许多局限性，包括抗癌活性低、溶解度和生物利用度低等。然而，由于黄连素的分子靶点不清楚，以往对黄连素的改造比较盲目和随机，并未取得较好的进展。胡天惠团队与张延东团队紧密合作、优势互补，针对黄连素与RXR的结合模式，运用结构生物学方法和全合成相结合，设计合成了多种黄连素衍生物，并开展了构效关系分析。发现黄连素衍生物B-12在结合并激活RXR、抗肠癌活性、溶解度和生物利用度方面均明显优于黄连素，且保留了黄连素的肿瘤选择性和低毒副作用，具有很好的临床转化前景。该研究也为结构生物学指导黄连素衍生物药物设计提供了理论基础。本论文的通讯作者为医学院占艳艳副教授、张延东教授和胡天惠教授。医学院博士生徐贝贝和化学化工学院博士生江训金为共同第一作者。We reported recently that berberine, a traditional oriental medicine to treat gastroenteritis, binds and activates Retinoid X receptor α (RXRα) to suppress the growth of colon cancer cells. Here, we extended our studies based on the binding mode of berberine with RXRα by design, synthesis and biological evaluation of a focused library of 15 novel berberine analogues. Among them, 3,9-dimethoxy-5,6-dihydroisoquinolino[3,2-a]isoquinolin-7-ium chloride (B-12) was identified as the optimal RXRα activator. More efficiently than berberine, B-12 bound and altered the conformation of RXRα/LBD, thereby suppressing Wnt/β-catenin pathway and colon cancer cell growth via RXRα mediation. In addition, B-12 not only preserved berberine’s tumor selectivity but also greatly improved its bioavailability. Remarkably, in mice, B-12 did not show obvious side effects including hypertriglyceridemia as other RXRα agonists, or induce hepatorenal toxicity. Together, our study describes an approach for the rational design of berberine-derived RXRα activators as novel effective antineoplastic agents for colon cancer.This work was supported by the National Natural Science Foundation of China (31770860, 21772164, 81572589, 81602560 and 21572187), and the Natural Science Foundation of Fujian Province (2018R1036-2, 2017J06020, 2019R1001-4, and 2019R1001-5). 项目得到了国家自然科学基金委促进海峡两岸科技合作联合基金重点项目、面上项目和福建省自然科学基金的支持

Active screen plasma surface co-alloying of 316 austenitic stainless steel with both nitrogen and niobium for the application of bipolar plates in proton exchange membrane fuel cells

AbstractAustenitic stainless steel has been researched as a promising candidate material for bipolar plates in proton exchange membrane fuel cells. However, its interfacial contact resistance (ICR) is about 16 times higher that of the Department of Energy (DOE) target (10 mΩ cm2), which leads to undesirable fuel cell performance. In this work, a new hybrid plasma surface engineering process, based on active screen plasma co-alloying, has been developed to simultaneously alloy 316 austenitic stainless steel (316 SS) surfaces with both nitrogen and niobium. The results demonstrated that the layer structure of the modified surfaces can be tailored by adjusting the treatment conditions. All the plasma treated 316 SS samples exhibited significantly reduced ICR below the DOE target of 10 mΩ cm2. The corrosion resistance of the N/Nb co-alloyed 316 SS was much better than active screen plasma nitrided and marginally better than the untreated material