In the open and closed space environments, the influence of spacing on battery pack thermal runaway propagation is studied. The mechanism of thermal runaway propagation for the lithium-ion battery ...pack is analyzed. The experimental results show that when the state of charge (SOC) of the battery is 100%, and the spacing is greater than 2 mm in the horizontal direction and 8 mm in the vertical arrangement, battery pack thermal runaway propagation hardly occurs in an open environment. In a closed environment, there is less chance of uncontrolled heat transmission in batteries when the rate of increase in the battery temperature is less than 0.66 °C s
−1
. When the horizontal spacing is more than 4 mm or the vertical spacing of the battery is more than 8 mm in a closed environment, thermal runaway propagation cannot occur in the batteries. The research results provide some reference for the arrangement of lithium-ion battery packs in transportation and storage.
Graphene nanosheets are impermeable to chemical molecules and electrical conductivity. Thus, they are attractive candidates to enhance an epoxy zinc rich coating with a significant anticorrosion ...performance. Several studies focus on investigating the role of graphene in reinforcing the corrosion resistance of the coatings. However, there is a paucity of study that analyzing the anticorrosion relationship between the feature of graphene and epoxy zinc rich coating. The present study reported on epoxy zinc rich coatings with enhanced anticorrosion performance via embedding reduced graphene oxide/graphene oxide (rGO/GO) nanosheets. Thus, rGO and GO were prepared from natural graphite powder via the modified Hummers method. The results of Raman, XPS, FT-IR, SPM, and TEM analyses revealed the quintessential structure and morphology of rGO and GO. In addition, results from electrochemical measurements and the scanning vibrating electrode technique indicated that rGO effectively enhanced the cathodic protection duration of epoxy zinc rich coatings. rGO nanosheets exhibited dual functions that were identified in two aspects. First, the impermeable barrier role was exerted by including prepared rGO nanosheets into the polymer matrix. Second, superior electrical conductivity was utilized since the rGO nanosheets improved the efficiency of the electrical connection between the zinc particles and steel substrate.
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•Well-designed rGO nanosheets were used for enhancing anticorrosion.•rGO can enhance the cathodic protection duration of epoxy zinc rich coating.•rGO endowed composite coating exhibited optimal anticorrosion capability.•SVET confirmed the cathodic protection property of the coating.
Summary
Enterotoxigenic Escherichia coli (ETEC) cause acute secretory diarrhoea in pigs, posing a great economic loss to the swine industry. This study analysed the prevalence and genetic ...characteristics of prophages from 132 ETEC isolates from symptomatic pigs to determine their potential for spreading antibiotic resistance. A total of 1105 potential prophages were identified, and the distribution of the genome size showed three ‘overlapping’ trends. Similarity matrix comparison showed that prophages correlated with the ETEC lineage distribution, and further identification of these prophages corroborated the lineage specificity. In total, 1206 antibiotic resistance genes (ARGs) of 52 different categories were identified in 132 ETEC strains; among these, 2.65% (32/1206) of ARGs were found to be carried by prophages. Analysis of flanking sequences showed that almost all the ARGs could be grouped into two types: ‘blaTEM‐1B’ and ‘classic class 1 integron (IntI1)’. They co‐occurred with a strictly conserved recombinase and transposon Tn3 family but with a difference: the ‘blaTEM‐1B type’ prophages exhibited a classic Tn2 transposon structure with 100% sequence identity, whereas the ‘IntI1 type’ co‐occurred with the TnAs2 transposon with only 84% sequence identity. These results imply that ARGs might be pervasive in natural bacterial populations through transmission by transposable bacteriophages.
Extraintestinal pathogenic
(ExPEC) is one of the top pathogens responsible for bloodstream infection and severe, often fatal, sepsis. Although the virulence factors and host immune responses to ExPEC ...infection have been investigated, the responses to a particular ExPEC strain could be very different. In this study, we investigated the mechanisms of Cyclooxygenase-2 (COX-2) up-regulation in influencing the host defenses against infection of ExPEC XM O2:K1:H7. Our results demonstrated that ExPEC XM O2:K1:H7 infection in mouse and RAW264.7 macrophages leads to COX-2 up-regulation, and COX-2 inhibition significantly enhances ExPEC infection. The up-regulation of COX-2 in macrophages was mediated by Toll-like receptor 4 (TLR4) through the activation of p38 and extracellular signal-regulated kinase/Mitogen-activated protein kinase (ERK/MAPK) pathways. Further studies showed that COX-2 inhibition significantly decreased autophagy in macrophages during ExPEC XM O2:K1:H7 infection. Autophagy inhibition significantly enhanced, while induction reduced ExPEC XM O2:K1:H7 survival in macrophages. In addition, COX-2 inhibition significantly increased macrophage cell death during ExPEC XM O2:K1:H7 infection and increased the expression of anti-inflammatory cytokine interleukin-10 (IL-10). Our results indicate that COX-2 up-regulation benefits host defense against ExPEC XM O2:K1:H7 infection by increasing autophagy in macrophages and by reducing IL-10 expression and macrophage cell death during ExPEC infection.
Urinary tract infections are primarily caused by uropathogenic
(UPEC). In contrast to the intestinal
strains that reside in nutrient-rich gut environment, UPEC encounter distinct niches, for instance ...human urine, which is an oxygen- and nutrient-limited environment. Alpha-ketoglutarate (KG) is an abundant metabolite in renal proximal tubule cells; and previously we showed that two-component signaling system (TCS) KguS/KguR contributes to UPEC colonization of murine urinary tract by promoting the utilization of KG as a carbon source under anaerobic conditions. However, knowledge about the KguR regulon and its impact on UPEC fitness is lacking. In this work, we analyzed transcriptomic and metabolomic changes caused by
deletion under anaerobiosis when KG is present. Our results indicated that 620 genes were differentially expressed in the Δ
mutant, as compared to the wild type; of these genes, 513 genes were downregulated and 107 genes were upregulated. Genes with substantial changes in expression involve KG utilization, acid resistance, iron uptake, amino acid metabolism, capsule biosynthesis, sulfur metabolism, among others. In line with the transcriptomics data, several amino acids (glutamate, lysine, etc.) and uridine 5'-diphosphogalactose (involved in capsule biosynthesis) were significantly less abundant in the Δ
mutant. We then confirmed that the Δ
mutant, indeed, was more sensitive to acid stress than the wild type, presumably due to downregulation of genes belonging to the glutamate-dependent acid resistance system. Furthermore, using gene expression and electrophoretic mobility shift assays (EMSAs), we demonstrate that KguR autoregulates its own expression by binding to the
promoter region. Lastly, we performed a genome-wide search of KguR binding sites, and this search yielded an output of at least 22 potential binding sites. Taken together, our data establish that in the presence of KG, KguR broadly impacts the physiology of UPEC under anaerobiosis. These findings greatly further our understanding of KguS/KguR system as well as UPEC pathobiology.
The oriental river prawn, Macrobrachium nipponense, is an important commercial aquaculture resource in China. In order to overwinter, M. nipponense displays decreased physiological activity and less ...consumption of energy. Sudden warming would trigger molting and cause an extensive death, resulting in huge economic losses. Therefore, it is of great practical significance to study the molting mechanism of oriental river prawns. Molt-inhibiting hormone gene (MIH) plays a major role in regulating molting in crustaceans. In this study, a full length MIH cDNA of M. nipponense (Mn-MIH) was cloned from the eyestalk. The total length of the Mn-MIH was 925 bp, encoding a protein of 119 amino acids. Tissue distribution analysis showed that Mn-MIH was highly expressed in the eyestalk, and that it had relatively low expression in gill, ovary, and abdominal ganglion. Mn-MIH was detected in all developmental stages, and changed regularly in line with the molting cycle of the embryo and larva. Mn-MIH varied in response to the molting cycle, suggesting that Mn-MIH negatively regulates ecdysteroidogenesis. Mn-MIH inhibition by RNAi resulted in a significant acceleration of molting cycles in both males and females, confirming the inhibitory role of MIH in molting. After long-term RNAi males, but not females had significant weight gain, confirming that Mn-MIH plays an important role in growth of M. nipponense. Our work contributes to a better understanding of the role of Mn-MIH in crustacean molting and growth.
Enterotoxigenic
(ETEC) cause severe diarrhea in humans and animals, leading to death and huge economic loss worldwide. Thus, elucidation of ETEC's pathogenic mechanisms will provide powerful data for ...the discovery of drugs serving as prevention or therapeutics against ETEC-caused diarrheal diseases. Here, we report that ArcA plays an essential role in the pathogenicity and virulence regulation in ETEC by positively regulating the expression of several key virulence factors including F18 fimbriae, heat-labile and heat-stable toxins, Shiga toxin 2e, and hemolysin, under microaerobic conditions and
. Moreover, we found that positive regulation of several virulence genes by ArcA requires a global repressor H-NS (histone-like nucleoid structuring), implying that ArcA may exert positive effects by antagonizing H-NS. Collectively, our data established a key role for ArcA in the pathogenicity of porcine ETEC and ETEC strains isolated from human infections. Moreover, our work reveals another layer of regulation in relation to oxygen control of virulence factors in ETEC.
To explore the relationship between serum thyrotropin and components of metabolic syndrome in a Chinese cohort. A total of 1534 adult inhabitants in DaDong district of Shenyang were asked to fulfill ...the questionnaire, complete physical examination and OGTT. Blood samples were collected to test thyrotropin (TSH), fasting plasma glucose (FPG), OGTT 2h PG, fasting insulin (FINS), triglyceride (TG) and high density lipoprotein cholesterol (HDL-C). Serum TSH in metabolic syndrome group was higher than that in the non-metabolic syndrome group (2.54 mIU/L vs. 2.22 mIU/L, p‹0.05). TG level increased significantly in subclinical hypothyroid group compared with euthyroid subjects (1.73±0.12 mmol/L vs. 1.47±0.03 mmol/L, p‹0.05), and HDL-C decreased significantly in patients with subclinical hypothyroidism compared with euthyroid subjects (1.26±0.27 mmol/L vs. 1.33±0.27 mmol/L, p‹0.05). The prevalence of hypertension was higher in the subclinical hypothyroid group than that in euthyroid group (42.86% vs. 33.2%, p‹0.05). The serum TSH within the reference range was positively related with the prevalence of overweight/obesity. Slight increase in serum TSH maybe a risk factor for metabolic syndrome.
Avian pathogenic Escherichia coli (APEC) belonging to extraintestinal pathogenic E. coli (ExPEC) can cause severe infections in extraintestinal tissues in birds and humans, such as the lungs and ...blood. MprA (microcin production regulation, locus A, herein renamed AbsR, a blood survival regulator), a member of the MarR (multiple antibiotic resistance regulator) transcriptional regulator family, governs the expression of capsule biosynthetic genes in human ExPEC and represents a promising druggable target for antimicrobials. However, a deep understanding of the AbsR regulatory mechanism as well as its regulon is lacking. In this study, we present a systems-level analysis of the APEC AbsR regulon using ChIP-Seq (chromatin immunoprecipitation sequencing) and RNA-Seq (RNA sequencing) methods. We found that AbsR directly regulates 99 genes and indirectly regulates 667 genes. Furthermore, we showed that: 1) AbsR contributes to antiphagocytotic effects by macrophages and virulence in a mouse model for systemic infection by directly activating the capsular gene cluster; 2) AbsR positively impacts biofilm formation via direct regulation of the T2SS (type II secretion system) but plays a marginal role in virulence; and 3) AbsR directly upregulates the acid tolerance signaling system EvgAS to withstand acid stress but is dispensable in ExPEC virulence. Finally, our data indicate that the role of AbsR in virulence gene regulation is relatively conserved in ExPEC strains. Altogether, this study provides a comprehensive analysis of the AbsR regulon and regulatory mechanism, and our data suggest that AbsR likely influences virulence primarily through the control of capsule production. Interestingly, we found that AbsR severely represses the expression of the type I-F CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR associated) systems, which could have implications in CRISPR biology and application.
Enterohemorrhagic Escherichia coli (EHEC) is a highly adaptive pathogen and has acquired diverse genetic elements, such as genomic islands and prophages, via horizontal gene transfer to promote ...fitness
. Two-component signaling systems (TCSs) allow bacteria to sense, respond to, and adapt to various environments. This study identified a putative two-component signaling system composed of the histidine kinase EDL5436 (renamed LmvK) and the response regulator EDL5428 (renamed LmvR) in EHEC.
and
along with
to
(
-
) between them constitute the OI167 genomic island and are highly associated with the EHEC pathotype.
-
encode transporters and metabolic enzymes that contribute to growth on mannose and are directly upregulated by LmvK/LmvR in the presence of mannose, as revealed by quantitative PCR (qPCR) and DNase I footprint assays. Moreover, LmvR directly activates the expression of the type III secretion system in response to mannose and promotes the formation of attaching and effacing lesions on HeLa cells. Using human colonoid and mouse infection models, we show that
and
contributed greatly to adherence and microcolony (MC) formation
and colonization
. Finally, RNA sequencing and chromatin immunoprecipitation coupled with sequencing analyses identified additional direct targets of LmvR, most of which are involved in metabolism. Given that mannose is a mucus-derived sugar that induces virulence and is preferentially used by EHEC during infection, our data revealed a previously unknown mechanism by which EHEC recognizes the host metabolic landscape and regulates virulence expression accordingly. Our findings provide insights into how pathogenic bacteria evolve by acquiring genetic elements horizontally to adapt to host environments.
The gastrointestinal tract represents a complex and challenging environment for enterohemorrhagic Escherichia coli (EHEC). However, EHEC is a highly adaptable pathogen, requiring only 10 to 100 CFUs to cause infection. This ability was achieved partially by acquiring mobile genetic elements, such as genomic islands, that promote overall fitness. Mannose is an intestinal mucus-derived sugar that stimulates virulence and is preferentially used by EHEC during infection. Here, we characterize the OI167 genomic island of EHEC, which encodes a novel two-component signaling system (TCS) and transporters and metabolic enzymes (EDL5429-5434) involved in mannose utilization. The TCS directly upregulates
-
and genes encoding the type III secretion system in the presence of mannose. Moreover, the TCS contributes greatly to EHEC virulence
and
. Our data demonstrate an elegant example in which EHEC strains evolve by acquiring genetic elements horizontally to recognize the host metabolic landscape and regulate virulence expression accordingly, leading to successful infections.
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