新一代复合材料的混合碳纤维和气相生长碳纤维的预构体

引言传统纤维复合材料的高性能只体现在平面型的增强材料上(一维或二维),由于基体的性质必然决定了材料在垂直于平面方向强度的限制。为了克服这种限制,人们已设计了各种多维增加纤维强度的方法。这包括     

在科罗拉多州RIFLE地区的MWX—2井内过金属套管测量地层电阻率

第二种测井下井仪器由顺磁测井股份有限公司设计并制造，在钢套管井中用以测量地层电阻率。原则上，这种新型的测井仪器的功能如同一支侧向测井或屏蔽电极（测井）仪，但却是在下套管井内进行测量。先前用第一种测井下井仪器旨在研究井内进行测量并证实理论上的可行性。第二种测井仪与第一种测井仪相比，改进了纵向分辨能力，提高了测量速度和测量精确度（尽管为点测）。从第一种和第二种测井仪所获得的数据表明，生产测井理论分析结     

Diversity of Salmonella isolates using serotyping and multilocus sequence typing

One hundred and twenty-one Salmonella isolates were obtained from food, feed, and live chicken samples derived from 13 countries or regions. In this study, their subtypes were evaluated by serotyping and multilocus sequence typing (MLST), and their genetic profiles were also characterized. It was demonstrated by serotyping on these isolates that 36 various serovars were obtained in this study, of which three serotypes S. Babelsberg, S. Fresno, and S. II were first found in mainland China. Based on Simpson’s index of diversity, the serotyping method had a 0.943 discriminatory power. Meanwhile, there were a total of 42 unique sequence types (STs) characterized by MLST, and the discriminatory power of MLST (D = 0.947) was close to that of the serotyping method. In MLST, hisD revealed the highest levels of nucleotide diversity. In addition, ST-92 was the most common ST represented by 16 Salmonella isolates, followed by ST-367 which was represented by 14 isolates. Seven new alleles were identified, which were associated with other alleles and resulted in the assignment of nine new STs. It was concluded from the results that MLST was generally associated with serotype, but not associated with the epidemiological source of the samples, and antimicrobial resistance patterns.     

Multifunctional picoliter droplet manipulation platform and its application in single cell analysis

We developed an automated and multifunctional microfluidic platform based on DropLab to perform flexible generation and complex manipulations of picoliter-scale droplets. Multiple manipulations including precise droplet generation, sequential reagent merging, and multistep solid-phase extraction for picoliter-scale droplets could be achieved in the present platform. The system precision in generating picoliter-scale droplets was significantly improved by minimizing the thermo-induced fluctuation of flow rate. A novel droplet fusion technique based on the difference of droplet interfacial tensions was developed without the need of special microchannel networks or external devices. It enabled sequential addition of reagents to droplets on demand for multistep reactions. We also developed an effective picoliter-scale droplet splitting technique with magnetic actuation. The difficulty in phase separation of magnetic beads from picoliter-scale droplets due to the high interfacial tension was overcome using ferromagnetic particles to carry the magnetic beads to pass through the phase interface. With this technique, multistep solid-phase extraction was achieved among picoliter-scale droplets. The present platform had the ability to perform complex multistep manipulations to picoliter-scale droplets, which is particularly required for single cell analysis. Its utility and potentials in single cell analysis were preliminarily demonstrated in achieving high-efficiency single-cell encapsulation, enzyme activity assay at the single cell level, and especially, single cell DNA purification based on solid-phase extraction.