Pressure induced superconductivity bordering a charge-density-wave state in NbTe4 with strong spinorbit coupling

Transition-metal chalcogenides host various phases of matter, such as charge-density wave (CDW), superconductors, and topological insulators or semimetals. Superconductivity and its competition with CDW in low-dimensional compounds have attracted much interest and stimulated considerable research. Here we report pressure induced superconductivity in a strong spin-orbit (SO) coupled quasi-one-dimensional (1D) transition-metal chalcogenide NbTe$_4$, which is a CDW material under ambient pressure. With increasing pressure, the CDW transition temperature is gradually suppressed, and superconducting transition, which is fingerprinted by a steep resistivity drop, emerges at pressures above 12.4 GPa. Under pressure $p$ = 69 GPa, zero resistance is detected with a transition temperature $T_c$ = 2.2 K and an upper critical field $H_{c2}$= 2 T. We also find large magnetoresistance (MR) up to 102\% at low temperatures, which is a distinct feature differentiating NbTe$_4$ from other conventional CDW materials.Comment: https://rdcu.be/LX8

Sub-MIC Tylosin Inhibits Streptococcus suis Biofilm Formation and Results in Differential Protein Expression

Streptococcus suis (S. suis) is a crucial zoonotic pathogen which causes severe diseases in humans and pigs. Biofilms of S. suis can induce persistent infections which are harder to treat. Sub-minimal inhibitory concentration (sub-MIC) of tylosin can inhibit biofilm formation in bacteria. By using iTRAQ strategy, we compared the protein expression profiles of S. suis grown with sub-MIC tylosin treatment or no treatement. The result showed that 96 proteins expression were changed with 77 up-regulated and 19 down-regulated proteins. Several metabolism proteins (such as phosphoglycerate kinase), as well as cell surface proteins (such as ABC transporter proteins), were found to be involved in biofilm formation. Overall, our results indicated that S. suis metabolic regulation, cell surface proteins, and virulence proteins appear to be of importance in biofilm growth by sub-MIC tylosin treated. Thus, our data analyzed rough regulation of biofilm formation that lay the foundation for the future research of mechanism and targets

Maternal ambient air pollution exposure with spatial-temporal variations and preterm birth risk assessment during 2013-2017 in Zhejiang Province, China.

Preterm birth (PTB) can give rise to significant neonatal morbidity and mortality, as well as children's long-term health defects. Many studies have illustrated the associations between ambient air pollution exposure during gestational periods and PTB risks, but most of them only focused on one single air pollutant, such as PM2.5. In this population-based environmental-epidemiology study, we recruited 6275 pregnant mothers in Zhejiang Province, China, and evaluated their gestational exposures to various air pollutants during 2013-2017. Time-to-event logistic regressions were performed to estimate risk associations after adjusting all confounders, and Quasi-AQI model and PCA-GLM analysis were applied to resolve the collinearity issues in multi-pollutant regression models. It was found that gestational exposure to ambient air pollutants was significantly associated with the occurrence of PTB, and SO2 was the largest contributor with a proportion of 29.4%. Three new variables, prime factor (a combination of PM2.5, PM10, SO2, and NO2), carbon factor (CO), and ozone factor (O3), were generated by PCA integration, contributing 63.4%, 17.1%, and 19.5% to PTB risks, respectively. The first and third trimester was the most crucial exposure window, suggesting the pregnant mothers better to avoid severe air pollution exposures during these sensitive periods

Single-particle coal ignition and alkali metal radiation characteristics based on optical diagnosis technology

Study on the ignition characteristics of coal is the theoretical basis for realizing the high-efficient and clean utilization of coal. The alkali metals such as K and Na in coal are released into the gas phase during combustion and enter the system, which can easily cause high temperature corrosion of the reactor, fouling of the heating surface and slagging in the furnace. Based on the single-particle coal ignition detection platform, the ignition and alkali metal Na* and K* radiation characteristics of single-particle Yangchangwan (YCW) bituminous coal and Naomaohu (NMH) lignite during combustion were investigated under different oxygen volume flow rates. High-speed camera technology was used to capture the flame evolution process during single-particle coal ignition, and hyperspectral imaging technology was used to measure the spontaneous emission spectra of alkali metals Na* and K* in the flame to obtain the spatial release behavior of alkali metals. The results show that the ignition process of different types of coal is different. The enveloping flame is formed in the combustion process of volatile matter in the YCW coal particles, while the ignition reaction of the NMH coal is more intense without enveloping phenomenon due to its high volatile matter content, and the flame brightness in the whole ignition process is stronger than that of the YCW coal. The increase of oxygen can promote the ignition of coal particles, with the increase of oxygen volume flow, the ignition delay time of the YCW coal and the NMH coal decreases, and the ignition delay time of the NMH coal is smaller than that of the YCW coal. When the fire occurs, the flame brightness is the brightest, and the flame shape is relatively smooth and stable. The radiation characteristics of alkali metals Na* and K* in single-particle YCW coal and NMH coal during ignition and combustion are different from that in coke combustion process, in which the radiation intensity of Na* and K* is the strongest. Na* has a release peak both in the volatile reaction process and coke reaction process, but K* radiation intensity does not have an obvious release peak in the volatile reaction process and coke combustion process. When oxygen content increases, the release time of alkali metals from the YCW coal and the NMH coal is gradually advanced, and the beginning time of alkali metal radiation from the NMH coal is less than that from the YCW coal. In addition, the analysis of the ignition process of single-particle coal shows that the release intensity of alkali metals Na* and K* in the peripheral position of the combustion flame is stronger than that in the central position