Novel method for processing respiratory specimens for detection of mycobacteria by using C18-carboxypropylbetaine: blinded study

A novel method for processing respiratory specimens to improve culture and acid-fast staining of mycobacteria is introduced. This new method utilized N,N-dimethyl-N-(n-octadecyl)-N-(3-carboxypropyl)ammonium inner salt (Chemical Abstract Service no. 78195-27-4), also known as C18-carboxypropylbetaine (CB-18). In a blinded, five-center study, CB-18-based processing was compared to the standard method combining NALC and NaOH (NALC/NaOH). A total of 573 respiratory specimens were tested. Individual specimens were split approximately equally; the host institutions processed half of each specimen by the NALC/NaOH method, while the other half was processed with CB-18 at Quest Diagnostics--Baltimore. A total of 106 specimens were culture positive for acid-fast bacilli (AFB). Replacement of the primary decontamination agent with CB-18 caused changes in all diagnostic parameters. Aggregate culture sensitivity improved by approximately 43% (P < 0.01), and smear sensitivity improved by approximately 58% (P < 0.01). The sensitivity of smear relative to that of M. tuberculosis isolates exceeded 93% (P < 0.01) when specimens were processed with CB-18. The average times to a positive result were reduced by 7.3 days in liquid culture (P < 0.01) and 5.3 days on solid media (P < 0.05); however, the CB-18 method had a 20.8% contamination rate in liquid culture versus a rate of approximately 7.5% with NALC/NaOH processing. There were also unusual reductions in liquid culture sensitivity and smear specificity among CB-18-processed specimens. The characteristics of the latter parameters suggested that refinement of the CB-18 processing method should allow further improvements in culture sensitivity. This study showed that the CB-18 method has the potential to improve both smear and culture detection for these important human pathogens.     

基于认知模型的Andon系统界面布局优化

针对用户观察Andon系统界面时的认知时间浪费问题,对A ndo n系统界面布局进行优化,以减少它对用户认知过程造成的影响.给出了通过建立认知模型找出重点认知模块,按照一致性、易读性、简洁性和整体性原则进行布局优化设计的方法,并建立了该方法的评价指标体系.结果表明,布局优化设计方案的综合评价指标优化提升率为16％.眼动实验证明,基于认知模型的界面布局优化,使用户在寻找特定信息时能将平均注视点个数和搜寻时间分别减少51％ 和54％.     

Ultrasensitive Self-Driven Terahertz Photodetectors Based on Low-Energy Type-II Dirac Fermions and Related Van der Waals Heterojunctions

The exotic electronic properties of topological semimetals (TSs) have opened new pathways for innovative photonic and optoelectronic devices, especially in the highly pursuit terahertz (THz) band. However, in most cases Dirac fermions lay far above or below the Fermi level, thus hindering their successful exploitation for the low-energy photonics. Here, low-energy type-II Dirac fermions in kitkaite (NiTeSe) for ultrasensitive THz detection through metal-topological semimetal-metal heterostructures are exploited. Furthermore, a heterostructure combining two Dirac materials, namely, graphene and NiTeSe, is implemented for a novel photodetector exhibiting a responsivity as high as 1.22 A W⁻¹, with a response time of 0.6 µs, a noise-equivalent power of 18 pW Hz^−0.5, with outstanding stability in the ambient conditions. This work brings to fruition of Dirac fermiology in THz technology, enabling self-powered, low-power, room-temperature, and ultrafast THz detection.     

In situ pultrusion of urea–formaldehyde matrix composites. I. Processability,kinetic analysis,and dynamic mechanical properties

We conducted a feasibility study on the pultrusion of a glass‐fiber‐reinforced urea–formaldehyde (UF) composite using a proprietary method. The UF prepolymer synthesized in this study was prepared from blends of UF monomer and a curing agent (NH₄Cl).The process feasibility, kinetic analysis, and dynamic mechanical properties of the glass‐fiber‐reinforced UF composites by pultrusion were investigated. From investigations of the long pot life of the UF prepolymer, the high reactivity of the UF prepolymer, and excellent fiber wet‐out, we found that the UF resin showed excellent process feasibility for pultrusion. A kinetic model, dα/dt = A exp(?E/RT)α^m(1 ? α)ⁿ, is proposed to describe the curing behavior of a UF resin. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry scans with a multiple‐regression technique. The dynamic storage modulus of the pultruded‐glass‐fiber‐reinforced UF composites increased with increasing die temperature, filler content and glass‐fiber content and with decreasing pulling rate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1242–1251, 2002     

重庆市竞技体育的发展战略

采用调查访问法、文献资料法等,对重庆市竞技体育的发展状况、有利条件与制约因素进行了分析研究,探讨了实现重庆市竞技体育发展的战略途径与对策,针对重庆市竞技体育的管理体制、竞技体育人才、资金投入、体育设施等方面存在的问题提出了具体的改进措施.     

Investigation of stability of composite superconductors in typical coil configurations

The stability of various composite conductor designs in realistic coil environments has been examined. We measure the velocity of propagation or contraction of a normal region, the full recovery current, and the minimum propagating current in a coil segment. We examine the dependence of these measurements on background field, transport current, electrical insulation, cooling passage size and orientation, and proximity of other conductors. Comparison of experiment and calculation provides indirect information about local heat transfer to the helium bath and direct information about safe operating current limits for particular coil designs.     

没有科学的态度就没有水泥业界的革命——读“清华大学凝石技术863项目课题组”文章有感

今年夏秋之际,东南沿海的台风不断北上袭击各省,给人们的生命财产带来了巨大的损失和威胁。而与此同时,水泥业界也刮起了一场汹汹然有备而来的“凝石台风”,一时间,大有在年产10亿吨的水泥业,结束“混凝土文明”之势。因为炒作得言过其实,这股由商家运作、各媒体推波助澜的非理