食品和临床来源金黄色葡萄球菌对Caco-2细胞侵袭力的比较研究

目的 比较研究食品和临床来源金黄色葡萄球菌不同克隆系(Clonal complex,CC)菌株对Caco-2细胞的侵袭力和菌膜形成能力。方法 采用Caco-2细胞体外培养方法、庆大霉素与溶葡萄球菌酶保护试验,研究金黄色葡萄球菌12个不同来源的克隆系菌株对人体肠道表皮细胞的体外侵袭力;采用96孔板结晶紫染色法,评估不同菌株的菌膜形成能力。结果 体外侵袭能力试验结果表明CC5、CC30、CC25、CC59、CC239、 CC50和CC398等克隆系都具有细胞强侵袭株,与牲畜特异相关的CC9也展现出细胞强侵袭力,而CC1、CC72 、CC20和CC121等克隆系则明显具有较弱的细胞侵袭能力。此外,不同克隆系菌株菌膜形成的能力也具有一定差异,其中CC5、CC9、CC25和CC239等克隆系菌膜形成能力相比较强,而CC1、CC72、CC59和CC121等则菌膜形成能力较弱。进一步分析发现不同克隆系菌株的菌膜形成能力与细胞侵袭力呈现正相关(R=0.743)。结论 金黄色葡萄球菌不同克隆系菌株的细胞侵袭能力、菌膜形成能力具有一定差异,本研究结果能够为有效防控金黄色葡萄球菌临床感染提供重要支持。     

带式转载机机架的设计分析

由于带式转载机在运送物料的过程中承受着自重和物料的压力,为了在满足强度和刚度要求的情况下使机架所受的力以及变形最小,采用理论计算的方法并借助与Matlab工具进行分析设计,从而确定拉索吊点的合理位置.     

Reductions of Vibrio parahaemolyticus in Pacific oysters (Crassostrea gigas) by depuration at various temperatures

Consumption of raw oysters has been linked to several outbreaks of Vibrio parahaemolyticus infection in the United States. This study investigated effects of ice storage and UV-sterilized seawater depuration at various temperatures on reducing V. parahaemolyticus in oysters. Raw Pacific oysters (Crassostrea gigas) were inoculated with a mixed culture of five clinical strains of V. parahaemolyticus (10290, 10292, 10293, BE 98-2029 and 027-1c1) at levels of 10⁴⁻⁶ MPN/g. Inoculated oysters were either stored in ice or depurated in recirculating artificial seawater at 2, 3, 7, 10, 12.5, and 15 °C for 4–6 days. Holding oysters in ice or depuration of oysters in recirculating seawater at 2 or 3 °C for 4 days did not result in significant reductions (P > 0.05) of V. parahaemolyticus in the oysters. However, depuration at temperatures between 7 and 15 °C reduced V. parahaemolyticus populations in oysters by >3.0 log MPN/g after 5 days with no loss of oysters. Depuration at refrigerated temperatures (7–15 °C) can be applied as a post-harvest treatment for reducing V. parahaemolyticus in Pacific oysters.     

Dramatic Tuning of the Topological Hall Effect in AxRhO2 (A = K,Rb, and Cs) Crystals by Electron Concentration or Cation

Topological Hall effect, being an unconventional anomalous Hall effect, is originated from the real-space Berry curvature caused by the nontrivial topological spin textures in materials. Manipulations of nontrivial magnetic structure and related topological Hall effect are very important for the study of the chiral magnet. Herein, it is experimentally observed that the significant topological Hall conductivity σ_xy in antiferromagnetic K_0.5RhO₂ can reach 3.5% of ν = 1 quantum conductivity below 20 K. Furthermore, by adjusting the concentration of K-cation different from 0.5 in K_xRhO₂ or substituting the K cations by Rb or Cs to form Rb_0.5RhO₂ or Cs_0.5RhO₂, it is observed that the topological Hall effect is much weakened or even disappeared. This evolution, verified by the theoretical calculations, is attributed to the unstable ground state of the non-coplanar spin structure in K_xRhO₂ (x = 0.4 and 0.6) and Cs_0.5RhO₂. The significantly tunable topological Hall effect in A_xRhO₂ makes it prospective on logical/sensor devices of spintronics.     

开源许可证的选择:挑战和影响因素

开发者通常会为其开源代码选择不同的开源许可证来约束其使用条件,以期能有效地保护知识产权和维持软件的长远发展.然而,现有的开源许可证种类繁杂,开发者难以了解不同开源许可证间的差异,并且难以通过现有的开源许可证选择工具做出合适的选择——其使用要求开发者了解开源许可证相关条款并明确自己的业务需求.学术界虽然对开源许可证已有研...