Sintering and Mechanical Properties of (SiC + TiCx)p/Fe Composites Synthesized from Ti3AlC2, SiC,and Fe Powders

Ceramic-particle-reinforced iron matrix composites (CPR-IMCs) have been used in many fields due to their excellent performance. In this study, using the fast resistance-sintering technology developed by our team, iron matrix composites (IMCs) reinforced by both SiC and TiC_x particles were fabricated via the addition of SiC and Ti₃AlC₂ particles, and the resulting relative densities of the sintering products were up to 98%. The XRD and EDS analyses confirmed the in situ formation of the TiC_x from the decomposition of Ti₃AlC₂ during sintering. A significant hybrid reinforcing effect was discovered in the (SiC + TiC_x)_p/Fe composites, where the experimental strength and hardness of the (SiC + TiC_x)_p/Fe composites were higher than the composites of monolithic SiC_p/Fe and (TiC_x)_p/Fe. While, under the condition of constant particle content, the elongation of the samples reinforced using TiC_x was the best, those reinforced by SiC was the lowest, and those reinforced by (SiC + TiC_x) fell in between, which means the plastic response of (SiC + TiC_x)_p/Fe composites obeyed the rule of mixture. The successful preparation of IMCs based on the hybrid reinforcement mechanism provides an idea for the optimization of IMCs.     

Self-curing triphenol A-based phthalonitrile resin precursor acts as a flexibilizer and curing agent for phthalonitrile resin

Major problems currently limiting the widespread application of phthalonitrile resins are the high precursor melting point and volatility of the curing agent. Herein, a novel self-curing triphenol A-based phthalonitrile resin precursor (TPPA-Ph) was successfully synthesized by reacting α,α,α′-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene (TPPA) with 4-nitrophthalonitrile (NPh) via nucleophilic substitution. The presence of residual phenolic hydroxyl groups in the TPPA-Ph precursor promoted the curing reaction of phthalonitrile resin in the absence of an additional curing reagent. Self-cured TPPA-Ph resins exhibited relatively low melting points (less than 100 °C), high thermal stability, and a wide processing window (116 °C). Furthermore, the TPPA-Ph precursors contained phenolic hydroxyl and cyano groups that can be used as flexibilizers and curing agents to optimize other phthalonitrile resins. Resorcinol-based phthalonitrile resin (DPPH) cured with various amounts of TPPA-Ph possessed excellent thermal and thermo-oxidative stability with a 5% weight loss temperature exceeding 530 °C, T_gs above 380 °C, and a wide processing window and time. Therefore, as a novel precursor and curing agent for phthalonitrile resins, the triphenol A-based phthalonitrile resin is an ideal resin matrix for high-performance composites with broad application prospects in aerospace, shipping, machinery, and other high-tech fields.

Major problems currently limiting the widespread application of phthalonitrile resins are the high precursor melting point and volatility of the curing agent.     

COPD并发肺部感染TLR4/NF-κB通路与细胞因子水平及意义

目的分析慢性阻塞性肺疾病(COPD)并发肺部感染Toll样受体4(TLR4)/核因子κB(NF-κB)通路与细胞因子变化及临床意义。 方法选择2018年4月至2020年6月我院收治的COPD并发肺部感染患者68例为观察组,选择医院同时间段收治的COPD患者29例为对照组。对比2组TLR4mRNA、NF-κBmRNA及细胞因子表达水平。统计COPD并发肺部感染患者预后,Logistic多因素回归分析COPD并发肺部感染患者预后的影响。 结果两组白血胞介素-4(IL-4)、肿瘤坏死因子-α(TNF-α)、干扰素-α(IFN-α)、TLR4mRNA、NF-κBmRNA水平对比有显著性差异(P<0.05);68例COPD并发肺部感染患者,病死率为17.64%;病死者肺部感染病原菌为真菌占比、急性生理与慢性健康Ⅱ(APACHEⅡ)评分、TNF-α、TLR4mRNA、NF-κBmRNA水平显著高于存活者(P<0.05);Logistic回归结果显示,APACHEⅡ评分、TNF-α、TLR4mRNA及NF-κBmRNA水平为影响COPD并发肺部感染患者预后的因素(OR＝3.480、3.885、2.959、3.074,P<0.05)。 结论APACHEⅡ评分高、TLR4/NF-κB通路被激活及细胞因子水平升高是影响COPD并发肺部感染患者预后的因素。     

Targeted delivery of antigen to intestinal dendritic cells induces oral tolerance and prevents autoimmune diabetes in NOD mice

Aims/hypothesis

The intestinal immune system is an ideal target to induce immune tolerance physiologically. However, the efficiency of oral protein antigen delivery is limited by degradation of the antigen in the gastrointestinal tract and poor uptake by antigen-presenting cells. Gut dendritic cells (DCs) are professional antigen-presenting cells that are prone to inducing antigen-specific immune tolerance. In this study, we delivered the antigen heat shock protein 65-6×P277 (H6P) directly to the gut DCs of NOD mice through oral vaccination with H6P-loaded targeting nanoparticles (NPs), and investigated the ability of this antigen to induce immune tolerance to prevent autoimmune diabetes in NOD mice.

Methods

A targeting NP delivery system was developed to encapsulate H6P, and the ability of this system to protect and facilitate H6P delivery to gut DCs was assessed. NOD mice were immunised with H6P-loaded targeting NPs orally once a week for 7 weeks and the onset of diabetes was assessed by monitoring blood glucose levels.

Results

H6P-loaded targeting NPs protected the encapsulated H6P from degradation in the gastrointestinal tract environment and significantly increased the uptake of H6P by DCs in the gut Peyer’s patches (4.1 times higher uptake compared with the control H6P solution group). Oral vaccination with H6P-loaded targeting NPs induced antigen-specific T cell tolerance and prevented diabetes in 100% of NOD mice. Immune deviation (T helper [Th]1 to Th2) and CD4⁺CD25⁺FOXP3⁺ regulatory T cells were found to participate in the induction of immune tolerance.

Conclusions/interpretation

In this study, we successfully induced antigen-specific T cell tolerance and prevented the onset of diabetes in NOD mice. To our knowledge, this is the first attempt at delivering antigen to gut DCs using targeting NPs to induce T cell tolerance.

     

区域化多实验室不符合项情况分析

目的 对实验室管理体系运行中的不符合项及纠正/预防措施进行分析,查找管理体系运行存在的不足,为管理体系更好的运行提供参考依据.方法 收集实验室2012年度各类质量管理活动发现并提出的不符合项及纠正/预防措施,进行统计分析.结果 共发现并提出不符合项149个,按来源内部审核、管理评审、CNAS外部审核和质量监督,发现并提出的不符合项分别占总数的25.5％、2.01％、4.03％和68.46％;按要素发现并提出6个以上不符合项的要素有9个,不符合项的发现并提出均不超过总数的10％;按场所档案室、常规室（含免疫室）、HIV初筛室、生化室和其他场所,发现并提出不符合项分别占总数的39.22％、26.47％、9.80％、8.82％和15.69％.对发现并提出的不符合项实验室能够及时采取有效措施实施纠正并提交见证材料,对可能影响检测结果的因素实施了预防措施加以控制,实验室对纠正/预防措施实施效果进行了跟踪审核.结论 质量监督对管理体系运行发挥了充分的监督作用,不符合项涉及的要素多而分散,种类和地点复杂而面广,加强档案室的档案管理工作是今后质量管理工作中重点.实验室对不符合项的发现与提出逐步有了充分的认识,不符合项发现与提出逐步减少,质量管理水平逐步提高.     

Doping effect and oxygen defects boost room temperature ferromagnetism of Co-doped ZnO nanoparticles: experimental and theoretical studies

Co-doped ZnO nanoparticles with different dosage concentrations were fabricated by a thermal decomposition method. The nanoparticles show a pure wurtzite structure without the formation of a secondary phase or Co clusters, in which Co ions present as Co²⁺ and occupy Zn²⁺ tetrahedral sites within the ZnO matrix. All the samples show ferromagnetic properties at room temperature with nonzero coercivity and remanence magnetization. Besides, the magnetic data is also fitted by the model of bound magnetic polarons (BMP). By increasing the Co²⁺ doping concentration, the saturation magnetization values of Co-doped ZnO nanoparticles increase first and then decreases, which is related to the variation tendency of oxygen defects on the surface and the number of BMPs. This phenomenon can be ascribed to the formation of defect-induced BMPs, in which ferromagnetic coupling occurs at lower Co²⁺ concentration and Co²⁺–O²⁻–Co²⁺ antiferromagnetic coupling arises at higher Co²⁺ concentration. Air annealing experiments further demonstrate this result, in which the saturation magnetization of Co-doped ZnO nanoparticles is reduced after annealing in Air. The doping effect and oxygen defects on the magnetic ordering of Co-doped ZnO were calculated using density functional theory. The calculation results reveal that stable long-range magnetic ordering in Co-doped ZnO nanoparticles is mainly attributed to the localized spin moments from 3d electrons of Co²⁺ ions. Both the experimental and theoretical studies demonstrate that the ferromagnetism in Co-doped ZnO nanoparticles is originated from the combined effects of Co doping and oxygen vacancies. These results provide an experimental and theoretical view to understand the magnetic origination and tune the magnetic properties of diluted magnetic semiconductors, which is of great significance for spintronics.

Co-doped ZnO nanoparticles with different dosage concentrations were fabricated by a thermal decomposition method.