Atmospheric deposition of polycyclic aromatic compounds and associated sources in an urban and a rural area of Chongqing, China

Monthly bulk (dry + wet) deposition samples were collected at an urban and a rural site in Chongqing, southwestern China during May 2014 to April 2015 for analyzing the contents of parent polycyclic aromatic hydrocarbons (PPAHs) and three types of substituted PAHs (SPAHs) including oxygenated PAHs (OPAHs), nitrated PAHs (NPAHs) and methyl PAHs (MPAHs). Annual average (standard deviation) deposition fluxes of Sigma PPAHs, Sigma OPAHs, and MPAHs were 536 +/- 216; 221 +/- 118, and 131 +/- 41.9 ng/m(2)/d, respectively, in the urban area, and 347 +/- 185, 160 +/- 112, and 85.2 +/- 32.0 ng/m(2)/d, respectively in the rural area. Deposition of MNPAHs (6.01 +/- 3.93 and 3.91 +/- 4.84 ng/m(2)/d) were about two orders of magnitude lower than those of EPPAHs. In the urban area, temporal variations of PPAHs and MPAHs fluxes were positively correlated with particle deposition, while the trends of OPAHs and NPAHs were probably controlled by secondary formation. In the rural area, SPAHs and PPAHs deposition fluxes had similar temporal trends but differed from particle deposition. High relative humidity in Chongqing likely played an important role in facilitating the partitioning of OPAHs to atmospheric aerosols and resulting in the relatively high OPAHs level in winter. Principle component analysis identified secondary formation (21.7%) and combustion emission (52.7%) as two important contributors to polycyclic aromatic compounds (PACs) deposition fluxes in urban area. (C) 2017 Elsevier Ltd. All rights reserved

The protective role of chicken cathelicidin-1 against Streptococcus suis serotype 2 in vitro and in vivo

Abstract Streptococcus suis serotype 2 (SS2) is an important zoonotic pathogen with the characteristics of high mortality and morbidity, which brings great challenges to prevent and control epidemic disease in the swine industry. Cathelicidins (CATH) are antimicrobial peptides with antimicrobial and immunomodulatory activities. In this study, bactericidal and anti-inflammatory effects of chicken cathelicidin-1 (CATH-1) were investigated in vitro and in vivo against SS2 infection. The results show that CATH-1 exhibited a better bactericidal effect compared to other species’ cathelicidins including chickens (CATH-2, -3, and -B1), mice (CRAMP) and pigs (PMAP-36 and PR-39), which rapidly killed bacteria in 20 min by a time-killing curve assay. Furthermore, CATH-1 destroyed the bacterial morphology and affected bacterial ultrastructure as observed under electron microscopy. Moreover, CATH-1 antibacterial activity in vivo shows that CATH-1 increased survival rate of SS2-infected mice by 60% and significantly reduced the bacterial load in the lungs, liver, spleen, blood, and peritoneal lavage as well as the release of SS2-induced inflammatory cytokines including IL-1α, IL-1β, IL-12, and IL-18. Importantly, CATH-1 did not show severe histopathological changes in mice. Further studies on the mechanism of anti-inflammatory activity show that CATH-1 not only reduced the inflammatory response through direct neutralization, but also by regulating the TLR2/4/NF-κB/ERK pathway. This study provides a scientific basis for the research and development of antimicrobial peptides as new antimicrobial agents

Facile Synthesis of Laminated Si@C–Fe₃O₄ Composite from Exfoliation of Zintl Phase: A Promising Lithium Battery Anode with Superior Rate Capability and Cycling Stability

Two-dimensional (2D) silicon nanomaterial is a promising anode for lithium-ion batteries (LIBs) due to its large specific area, short ion transport path, and minimized volume expansion. However, its batch utilization is greatly limited by complicated synthesis procedures and time or energy consumption. Herein, we report a facile strategy to construct a kind of Si@C–Fe3O4 lamellar composite with enhanced performance as a LIB anode material. The 2D Si nanosheets are thermally exfoliated from the layered Zintl compound CaSi2 reacting with CO2, followed by surface coating of the C–Fe3O4 layer via the decomposition of ferrocene. Throughout 100 cycles, the as-synthesized Si@C–Fe3O4 composite maintains a stable specific capacity of 1000 mA h g–1 at 0.2 A g–1 with a subtle decay. Compared to 2D Si nanosheets, the composite exhibits better specific capacity and rate capability, particularly at high rates. It is found that C–Fe3O4 is an efficient and low-cost component for enhancing the lithium storage capability of Si-based anodes. We expect that this study will provide a simple and scalable path to the practical fabrication of Si-based anodes toward high-performance LIBs