2005--2014年CHINET中国细菌耐药性监测网5种重要临床分离菌的耐药性变迁

目的收集并分析CHINET中国细菌耐药性监测网中5种重要临床分离菌的耐药性变迁。方法采用纸片扩散法或自动化仪器法按统一方案进行药物敏感性试验。按CLSI 2014年版标准判断结果。结果 2005—2014年,每年的临床分离菌数量为22 774~84 572株。大肠埃希菌中产ESBL菌株检出率为51.7%~55.8%。在上述时期内大肠埃希菌和肺炎克雷伯菌对阿米卡星、环丙沙星、哌拉西林-他唑巴坦和头孢哌酮-舒巴坦的耐药率有所下降。肺炎克雷伯菌中碳青霉烯类耐药株由2.4%上升至13.4%。铜绿假单胞菌对包括亚胺培南和美罗培南的所有受试抗菌药物的耐药率均有所下降。鲍曼不动杆菌对碳青霉烯类的耐药率由31.0%逐步上升至66.7%。耐甲氧西林金黄色葡萄球菌的检出率由2005年的69%逐年下降至2014年的44.6%。结论国内肺炎克雷伯菌和鲍曼不动杆菌对碳青霉烯类的耐药率高。上述结果显示细菌耐药性监测对于细菌感染的有效治疗十分重要。

In vitro Study on Biodegradable AZ31 Magnesium Alloy Fibers Reinforced PLGA Composite

AZ31 magnesium alloy fibers reinforced poly（lactic-co-glycolic acid） （PLGA） composites were prepared and their mechanical property, immersion corrosion behavior and biocompatibility were studied. The tensile test showed that with the addition of AZ31 fibers, the composites had a significant increment in tensile strength and elongation. For the direct cell attachment test, all the cells showed a healthy morphology and spread well on the experimental sample surfaces. The immersion results indicated that pH values of the immersion medium increased with increasing AZ31 fiber contents. All the in vitro experimental results indicated that this new kind of magnesium alloy fibers reinforced PLGA composites show a potential for future biomedical applications.

The combined effects of grain and sample sizes on the mechanical properties and fracture modes of gold microwires

Hall-Petch relation was widely applied to evaluate the grain size effect on mechanical properties of metallic material. However, the sample size effect on the Hall-Petch relation was always ignored. In the present study, the mechanical test and microstructure observation were performed to investigate the combined effects of grain and sample sizes on the deformation behaviors of gold microwires. The polycrystalline gold microwires with diameter of 16 ?m were annealed at temperatures from 100°C to 600°C, leading to different ratios(t/d) of wire diameter(t) to grain size(d) from 0.9 to 16.7. When the t/d was lower than 10, the yield stress dropped fast and deviated from the Hall-Petch relation. The free-surface grains played key role in the yield stress softening, and the volume fraction of free-surface grains increased with the t/d decreasing. Furthermore, the effects of t/d on work-hardening behaviors and fracture modes were also studied. With t/d value decreasing from 17 to 3.4, the samples exhibited necking fracture and the dislocation pile-ups induced work-hardening stage was gradually activated.With the t/d value further decreasing(t/d < 3.4), the fracture mode turned into shear failure, and the work-hardening capability lost. As the gold microwire for wire bonding is commonly applied in the packaging of integrated circuit chips, and the fabrication of microwire suffers multi-pass cold-drawing and annealing treatments to control the grain size. The present study could provide instructive suggestion for gold microwire fabrication and bonding processes.

Measurement of the integrated luminosity of data samples collected during 2019-2022 by the Belle Ⅱ experiment

series of data samples was collected with the Belle Ⅱ detector at the SuperKEKB collider from March 2019 to June 2022.We determine the integrated luminosities of these data samples using three distinct methodologies involving Bhabha(e^(+)e^(-)→e^(+)e^(-)(ny),digamma(e^(+)e^(-)→γγ(nγ),and dimuon(e^(+)e^(-)→μ^(+)μ^(-)(nγ)events.The total integrated luminosity obtained with Bhabha,digamma,and dimuon events is(426.88±0.03±2.61)fb^(-1),(429.28±0.03±2.62)fb^(-1),and(423.99±0.04±3.83)fb^(-1),where the first uncertainties are statistical and the second are systematic.The resulting total integrated luminosity obtained from the combination of the three methods is(427.87±2.01)fb^(-1).