Nonlinear dynamic response analysis of a cantilever beam with a breathing crack

The nonlinear dynamic characteristics of plane cracked beam subjected to a harmonic load at the tip are researched. A crack opens and closes during vibration that is simulated as a frictionless plane contact problem, and a finite element contact model for a cantilever cracked beam is established. The quarter-point element is used to describe the crack tip singularity. Based on the proposed finite element contact model, the influence of excitation frequency, crack depth and crack position on nonlinear dynamic characteristics are discussed in detail. Relative amplitude of frequency spectrum with respect to different factors is analyzed to realize sub-harmonics or super-harmonics of cracked beam. The research results demonstrate that there is obvious nonlinear dynamic behavior for plane beam with a fatigue crack, and the different feature of frequency spectrum can be used to identify the beam damage in structure. Meanwhile, the strategy of experimental validation to the FEM results is discussed

VirBR, a transcription regulator, promotes IncX3 plasmid transmission, and persistence of bla NDM-5 in zoonotic bacteria

IncX3 plasmids carrying the New Delhi metallo-β-lactamase-encoding gene, blaNDM-5, are rapidly spreading globally in both humans and animals. Given that carbapenems are listed on the WHO AWaRe watch group and are prohibited for use in animals, the drivers for the successful dissemination of Carbapenem-Resistant Enterobacterales (CRE) carrying blaNDM-5-IncX3 plasmids still remain unknown. We observe that E. coli carrying blaNDM-5-IncX3 can persist in chicken intestines either under the administration of amoxicillin, one of the largest veterinary β-lactams used in livestock, or without any antibiotic pressure. We therefore characterise the blaNDM-5-IncX3 plasmid and identify a transcription regulator, VirBR, that binds to the promoter of the regulator gene actX enhancing the transcription of Type IV secretion systems (T4SS); thereby, promoting conjugation of IncX3 plasmids, increasing pili adhesion capacity and enhancing the colonisation of blaNDM-5-IncX3 transconjugants in animal digestive tracts. Our mechanistic and in-vivo studies identify VirBR as a major factor in the successful spread of blaNDM-5-IncX3 across one-health AMR sectors. Furthermore, VirBR enhances the plasmid conjugation and T4SS expression by the presence of copper and zinc ions, thereby having profound ramifications on the use of universal animal feeds

Balancing mcr-1 expression and bacterial survival is a delicate equilibrium between essential cellular defence mechanisms

MCR-1 is a lipid A modifying enzyme that confers resistance to the antibiotic colistin. Here, we analyse the impact of MCR-1 expression on E. coli morphology, fitness, competitiveness, immune stimulation and virulence. Increased expression of mcr-1 results in decreased growth rate, cell viability, competitive ability and significant degradation in cell membrane and cytoplasmic structures, compared to expression of catalytically inactive MCR-1 (E246A) or MCR-1 soluble component. Lipopolysaccharide (LPS) extracted from mcr-1 strains induces lower production of IL-6 and TNF, when compared to control LPS. Compared to their parent strains, high-level colistin resistance mutants (HLCRMs) show reduced fitness (relative fitness is 0.41–0.78) and highly attenuated virulence in a Galleria mellonella infection model. Furthermore, HLCRMs are more susceptible to most antibiotics than their respective parent strains. Our results show that the bacterium is challenged to find a delicate equilibrium between expression of MCR-1-mediated colistin resistance and minimalizing toxicity and thus ensuring cell survival

Environmental dissemination of mcr-1 positive Enterobacteriaceae by Chrysomya spp. (common blowfly): An increasing public health risk

Until recently, the role of insects, and particularly flies, in disseminating antimicrobial resistance (AMR) has been poorly studied. In this study, we screened blowflies (Chrysomya spp.) from different areas near the city of Phitsanulok, Northern Thailand, for the presence of AMR genes and in particular, mcr-1, using whole genome sequencing (WGS). In total, 48 mcr-1-positive isolates were recovered, consisting of 17 mcr-1-positive Klebsiella pneumoniae (MCRPKP) and 31 mcr-1-positive Escherichia coli (MCRPEC) strains. The 17 MCRPKP were shown to be clonal (ST43) with few single poly nucleomorphs (SNPs) by WGS analysis. In in-vitro models, the MCRPKP were shown to be highly virulent. In contrast, 31 recovered MCRPEC isolates are varied, belonging to 12 different sequence types shared with those causing human infections. The majority of mcr-1 gene are located on IncX4 plasmids (29/48, 60.42%), sharing an identical plasmid backbone. These findings highlight the contribution of flies to the AMR contagion picture in low- and middle-income countries and the challenges of tackling global AMR

Groundwater effects on net primary productivity and soil organic carbon: a global analysis

Groundwater affects ecosystem services (ES) by altering critical zone ecohydrological and biogeochemical processes. Previous research has demonstrated significant and nonlinear impacts of shallow groundwater on ES regionally, but it remains unclear how groundwater affects ES at the global scale and how such effects respond to environmental factors. Here, we investigated global patterns of groundwater relationships with two ES indicators—net primary productivity (NPP) and soil organic carbon (SOC)—and analyzed underlying factors that mediated groundwater influences. We quantitatively compared multiple high-resolution (∼1 km) global datasets to characterize water table depth (WTD), NPP and SOC, and performed spatial simultaneous autoregressive modeling to test how selected predictors altered WTD-NPP and WTD-SOC relationships. Our results show widespread significant WTD-NPP correlations (61.5% of all basins globally) and WTD-SOC correlations (64.7% of basins globally). Negative WTD-NPP correlations, in which NPP decreased with rising groundwater, were more common than positive correlations (62.4% vs. 37.6%). However, positive WTD-SOC relationships, in which SOC increased with rising groundwater, were slightly more common (53.1%) than negative relationships (46.9%). Climate and land use (e.g., vegetation extent) were dominant factors mediating WTD-NPP and WTD-SOC relationships, whereas topography, soil type and irrigation were also significant factors yet with lesser effects. Climate also significantly constrained WTD-NPP and WTD-SOC relationships, suggesting stronger WTD-NPP and WTD-SOC relationships with increasing temperature. Our results highlight that the relationship of groundwater with ES such as NPP and SOC are spatially extensive at the global scale and are likely to be susceptible to ongoing and future climate and land-use changes

Effects of Spontaneous Fluorescent Polystyrene on <i>Nostocaceae</i> and <i>Daphnia Magna</i>

Microplastic pollution is widespread around the world and inevitably comes into contact with organisms. With the accumulation of microplastics in the environment, the negative impact of microplastics on organisms has become the main focus in the field of microplastics. In this study, the different particle and concentration effects of fluorescent polystyrene microplastics (PS-MPs) on Nostocaceae and Daphnia Magna were researched. The results indicate that PS-MPs adhered to Nostocaceae through static electricity, which hindered the absorption of photons and CO2 by Nostocaceae, resulting in a decrease in chlorophyll, a low growth rate and high mortality for Nostocaceae. PS-MPs with very small particles may be integrated into the blood of Daphnia Magna, leading to an increasing trend of mortality and a decrease in spawning rate. The research provides basic data and a reference for the effect of PS-MPs on freshwater organisms and has implications for the further study of microplastics

<strong>Groundwater effects on net primary productivity and soil organic carbon: a global analysis</strong>

The data and R code to reproduce the results of the manuscript entitled "Groundwater effects on net primary productivity and soil organic carbon: a global analysis" are provided in this repository. Following files are provided: (1) README.txt: Additional information of R code and data. (2) WTD-NPP-SOC.R : R code for statistical analysis. (3) Basin07_100.tif : Basin boundary gridded dataset (basins with areas 2 have been filtered out to avoid unrobust results). (4)  WTD_GDbelow5.tif : Groundwater table depth gridded dataset (grid cells with the gap distance ≤ 5 m are used for statistical analysis). (5)  NPPmean_GDbelow5.tif : Annual average NPP (2000-2015) gridded dataset (grid cells with the gap distance ≤ 5 m are used for statistical analysis). (6)  NPPsd_GDbelow5.tif : Standard deviation of annual average NPP (2000-2015) gridded dataset (grid cells with the gap distance ≤ 5 m are used for statistical analysis). (7)  sc015_GDbelow5.tif : Soil organic carbon stock of shallow soil layer from 0 to 15 cm depth gridded dataset (grid cells with the gap distance ≤ 5 m are used for statistical analysis). (8)  sc0200_GDbelow5.tif : Soil organic carbon stock of deep soil layer from 0 to 200 cm depth gridded dataset (grid cells with the gap distance ≤ 5 m are used for statistical analysis). (9)  Basin07_centxy_region.csv : Table of the center cordinates and the regional information of basins. (10)  BasinIDnew.csv : Table of reordered ID of basins. (11)  Environmental_factors.csv : Table of environmental factors of basins. (12)  Cor_WTD_NPPmean.csv : Results of WTD-NPP mean correlations. (13)  Cor_WTD_NPPsd.csv : Results of WTD-NPP SD(standard deviation) correlations. (14)   Cor_WTD_sc015.csv  : Results of WTD-SOC correlations at 0-15 cm soil deep. (15)   Cor_WTD_sc0200.csv  : Results of WTD-SOC correlations at 0-200 cm soil deep. (16)  PWTDNPPmean.gal : Spatial weights of positive WTD-NPP mean correlations. (17)  NWTDNPPmean.gal : Spatial weights of negative WTD-NPP mean correlations. (18)  PWTDNPPsd.gal : Spatial weights of positive WTD-NPP SD correlations. (19)  NWTDNPPsd.gal : Spatial weights of negative WTD-NPP SD correlations. (20)  PWTDsc015.gal : Spatial weights of positive WTD-SOC correlations at 0-15 cm soil deep. (21)  NWTDsc015.gal : Spatial weights of negative WTD-SOC correlations at 0-15 cm soil deep. (22)  PWTDsc0200.gal : Spatial weights of positive WTD-SOC correlations at 0-200 cm soil deep. (23)  NWTDsc0200.gal : Spatial weights of negative WTD-SOC correlations at 0-200 cm soil deep. (24) BestSAR_coe.csv : Coefficients between WTD-NPP/SOC relationships and environmental factors from the optimal SAR models. (25) BestSAR_p.csv : P-values of the coefficients between WTD-NPP/SOC relationships and environmental factors from the optimal SAR models. </p

Lignin bioconversion based on genome mining for ligninolytic genes in Erwinia billingiae QL-Z3

Abstract Background Bioconversion of plant biomass into biofuels and bio-products produces large amounts of lignin. The aromatic biopolymers need to be degraded before being converted into value-added bio-products. Microbes can be environment-friendly and efficiently degrade lignin. Compared to fungi, bacteria have some advantages in lignin degradation, including broad tolerance to pH, temperature, and oxygen and the toolkit for genetic manipulation. Results Our previous study isolated a novel ligninolytic bacterial strain Erwinia billingiae QL-Z3. Under optimized conditions, its rate of lignin degradation was 25.24% at 1.5 g/L lignin as the sole carbon source. Whole genome sequencing revealed 4556 genes in the genome of QL-Z3. Among 4428 protein-coding genes are 139 CAZyme genes, including 54 glycoside hydrolase (GH) and 16 auxiliary activity (AA) genes. In addition, 74 genes encoding extracellular enzymes are potentially involved in lignin degradation. Real-time PCR quantification demonstrated that the expression of potential ligninolytic genes were significantly induced by lignin. 8 knock-out mutants and complementary strains were constructed. Disruption of the gene for ELAC_205 (laccase) as well as EDYP_48 (Dyp-type peroxidase), ESOD_1236 (superoxide dismutase), EDIO_858 (dioxygenase), EMON_3330 (monooxygenase), or EMCAT_3587 (manganese catalase) significantly reduced the lignin-degrading activity of QL-Z3 by 47–69%. Heterologously expressed and purified enzymes further confirmed their role in lignin degradation. Fourier transform infrared spectroscopy (FTIR) results indicated that the lignin structure was damaged, the benzene ring structure and groups of macromolecules were opened, and the chemical bond was broken under the action of six enzymes encoded by genes. The abundant enzymatic metabolic products by EDYP_48, ELAC_205 and ESOD_1236 were systematically analyzed via liquid chromatography–mass spectrometry (LC–MS) analysis, and then provide a speculative pathway for lignin biodegradation. Finally, The activities of ligninolytic enzymes from fermentation supernatant, namely, LiP, MnP and Lac were 367.50 U/L, 839.50 U/L, and 219.00 U/L by orthogonal optimization. Conclusions Our findings provide that QL-Z3 and its enzymes have the potential for industrial application and hold great promise for the bioconversion of lignin into bioproducts in lignin valorization

VirBR, a transcription regulator, promotes IncX3 plasmid transmission, and persistence of blaNDM-5 in zoonotic bacteria.

Acknowledgements: This work was supported in part by grants from the National Natural Science Foundation of China (32141002 to S.J.Z., 81991535 to W.C.M., and 32202868 to M.T.F.), the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030007 to W.Y.), and the UK Medical Research Council (project DETER-XDR-China-HUB, grant number MR/S013768/1 to T.R.W.). The funders had no role in study design, data collection, and interpretation, or the decision to submit the work for publication.IncX3 plasmids carrying the New Delhi metallo-β-lactamase-encoding gene, blaNDM-5, are rapidly spreading globally in both humans and animals. Given that carbapenems are listed on the WHO AWaRe watch group and are prohibited for use in animals, the drivers for the successful dissemination of Carbapenem-Resistant Enterobacterales (CRE) carrying blaNDM-5-IncX3 plasmids still remain unknown. We observe that E. coli carrying blaNDM-5-IncX3 can persist in chicken intestines either under the administration of amoxicillin, one of the largest veterinary β-lactams used in livestock, or without any antibiotic pressure. We therefore characterise the blaNDM-5-IncX3 plasmid and identify a transcription regulator, VirBR, that binds to the promoter of the regulator gene actX enhancing the transcription of Type IV secretion systems (T4SS); thereby, promoting conjugation of IncX3 plasmids, increasing pili adhesion capacity and enhancing the colonisation of blaNDM-5-IncX3 transconjugants in animal digestive tracts. Our mechanistic and in-vivo studies identify VirBR as a major factor in the successful spread of blaNDM-5-IncX3 across one-health AMR sectors. Furthermore, VirBR enhances the plasmid conjugation and T4SS expression by the presence of copper and zinc ions, thereby having profound ramifications on the use of universal animal feeds

Conducting polymers from aminobenzoic acids and aminobenzenesulphonic acids: influence of pH on electrochemical behaviour

The influence of pH on the electrochemical behaviour of conducting polymer films electrosynthesised from aminobenzoic acids and aminobenzenesulphonic acids was investigated by voltammetric and electrochemical impedance studies in sulphuric acid solution, acetate buffer and neutral phosphate buffer. The change in electrochemical behaviour with increasing pH is significantly less for poly(aminobenzenesulphonic acid)s and poly(aminobenzoic acid)s than for polyaniline. Polymer films made by electrosynthesis of mixtures of these monomers with aniline have also been analysed by the same techniques. Experimental results obtained over this pH range are interpreted in the light of previous studies carried out on these polymers in strong acid solution.http://www.sciencedirect.com/science/article/B6TGB-479KCT3-2/1/996537b5327d9ca5219aa836e384a17