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Background Chinese resident physicians confront challenges such as staff shortages and heavy workloads, leading to a heightened prevalence of mental distress. This study aims to investigate the symptom network of stress, burnout, anxiety, depression (SBAD) and adverse personal outcomes in this cohort.Methods From October 2020 to April 2022, 994 physicians were recruited across China through snowball sampling. Stress, burnout, anxiety and depression were assessed using the 10-item Perceived Stress Scale, a two-item burnout questionnaire, Generalized Anxiety Disorder Scale-7 and the Patient Health Questionnaire-9, respectively. Data on adverse personal outcomes (low quality of life [QOL] and suicidal ideation) were collected. We constructed and visualized two networks, calculating expected influence (EI) and bridge EI indices to identify central and bridge symptoms.Results In the SBAD network, perceived helplessness was the most central and critical bridge symptom connecting stress and mental distress, with emotional exhaustion identified as the secondary bridge symptom. Perceived helplessness, perceived self-efficacy and emotional exhaustion exhibited the highest negative correlations with QOL. Worthless (PHQ6) and motor (PHQ8) symptoms were strongly correlated with suicidal ideation. The estimated SBAD network showed excellent stability and accuracy.Conclusions Our study emphasizes that perceived helplessness may be a high-priority target for preventing and intervening in mental distress and improving QOL among residents. Burnout transcends workplace problems and is widely connected to depression, anxiety and QOL. Implementing early detection and intervention measures at three levels—the individual physician, health system and professional colleges, and external regulators—is crucial for preventing and alleviating stress and mental distress among residents.

Land surface temperature (LST) is a crucial physical parameter for hydrological, meteorological, climatological, and climate change studies. To encourage the use of satellite-derived LST products in a wide range of applications, providing feedback on product performance over regional and global scales is an urgent task. However, considering that the uncertainty of newly released LST products is still unclear, it is urgently necessary to perform a comprehensive validation and error analysis, especially in areas with special geographical and weather conditions, such as the Tibetan plateau (TP). In particular, fewer studies have been concerned with the degraded LST retrieval accuracy over the TP because of the sparse ground measurements. In this study, moderate-resolution imaging spectroradiometer (MODIS) LST products (C6.1) were comprehensively evaluated based on the independent ground observation systems with different atmospheric and LST conditions. The in situ measurements collected from the Tibetan Observation and Research Platform and surface radiation systems are located on the American Plain and the TP, respectively, incorporating various land-cover types, including barren land, grassland, cropland, shrubland, and sparse and dense vegetation, among others. The spatial representativeness evaluation indicated that relatively high-quality in situ LSTs can be obtained during nighttime. Compared with the North American Plain (with a mean RMSE of 1.56 K), MODIS LST retrievals have larger discrepancies (mean RMSE of 2.34 K) over the TP with complex terrain and weather conditions. Emissivity determination is the primary source of the uncertainty in the generalized split-window (GSW) algorithm. Moreover, simulation settings of atmospheric and LST conditions in the GSW algorithm cannot cover a wide range of conditions at a global scale. It is expected to develop new LST retrieval algorithm to meet the quality specifications of users over the TP. Overall, this study identifies critical further research needs and improves the understanding of LST product performance under complex circumstances.

New advances in top-down construction are developing with the construction of supertall buildings in China. This study presents a finite element analysis for high-rise structural construction with a top-down method (TDM) considering complex environmental conditions. Based on this analysis model, the forces and the deformation of the diaphragm wall, beams, and soldier piles at various stages of construction are computed. Taking a super high-rise building with a 5-story basement in Nanjing as an example, the reliability and accuracy of the model is verified by comparing the measured and simulated results of displacement and stress values at various locations. The research results reveal the relationship between excavation depth, soil settlement and pile displacement, which is convenient for finding the optimal construction critical surface. It lays a foundation for the study of the critical height of the subsequent construction and facilitates the prediction of the weak link in the process. At present, this project is under construction, so this study has reference value for subsequent construction projects.

ABSTRACTAs a type of environmentally deleterious compound, 4-nitrophenol (4-NP) has become a global concern due to its extreme toxicity to aquatic organisms and humans. Herein, we used naturally available crayfish shells as precursors to prepare a new type of carbon dots (CDs) by the hydrothermal method. The as-synthesized CDs exhibited strong blue fluorescence emission which can be sensitively quenched by 4-NP through the static quenching effect because of the formation of a ground state complex between CDs and 4-NP. Accordingly, a facile and rapid fluorescence sensor was developed to detect 4-NP from 0 μM to 50 μM with a limit of detection (LOD) of 0.16 μM. Furthermore, the proposed sensor was successfully applied for the detection of 4-NP in fresh crayfish meat and aquatic water samples.

Land surface temperature (LST) plays a crucial role in the energy and water cycles of the Earth's climate system. The uncertainty of LST retrieval from satellites is a fundamental and long-standing issue, especially in plateau areas [such as the Tibetan Plateau (TP)], due to its high altitude, unique hydrometeorological conditions, and complex underlying surfaces. To improve the accuracy of LST retrieval over the TP, different methods, including the single channel (SC) algorithm, the split-window (SW) algorithm, and four machine learning (ML) models, were used to retrieve the LST based on sea and land surface temperature radiometer (SLSTR) data in this study. The validation results indicated that the root-mean-square errors (RMSEs) of the LSTs retrieved by the SC and SW algorithms were 3.48 and 2.64 K, respectively, which shows a better performance than the official SLSTR LST products (5.23 K). In addition, the random forest model has the highest accuracy among the four ML models, with an RMSE of 3.26 K. By comparing the performance of various methods, the SW algorithm is more stable and reliable for LST retrieval over the TP. In addition, the accurate spatiotemporal distribution of the LST based on the SW algorithm was also analyzed, which would benefit the understanding of the physical processes of energy and water cycles over the TP.

Gold-coated silver core–shell nanoparticles (Ag@Au NPs) have been widely used for SERS analysis due to plasmon resonance performances. However, it is a great challenge to fabricate Ag@Au core–shell structures with specified morphology. In this paper, the size and shape of Ag NPs (core) were precisely controlled by a seed-mediated approach, and then the gold shell was completely coated on under the strong reduction of ascorbic acid, resulting in Ag@Au NPs with highly regulated morphology. The obtained Ag@Au NPs achieved a similar or even better SERS enhancement factor (EF) (up to 5.7 × 107) compared to Ag NPs, but significantly higher stability. For the rapid SERS detection of nitrofurantoin metabolite AHD, a limit of detection (LOD) as low as 1 × 10−10 M and a wide linear range from 1 × 10−4 to 1 × 10−8 M were obtained. Furthermore, recoveries for crayfish samples were from 90.5% to 108%, indicating a good performance of the presented method in real sample detection.

The drawbacks of a one-dimensional chaotic map are its straightforward structure, abrupt intervals, and ease of signal prediction. Richer performance and a more complicated structure are required for multidimensional chaotic mapping. To address the shortcomings of current chaotic systems, an n-dimensional cosine-transform-based chaotic system (nD-CTBCS) with a chaotic coupling model is suggested in this study. To create chaotic maps of any desired dimension, nD-CTBCS can take advantage of already-existing 1D chaotic maps as seed chaotic maps. Three two-dimensional chaotic maps are provided as examples to illustrate the impact. The findings of the evaluation and experiments demonstrate that the newly created chaotic maps function better, have broader chaotic intervals, and display hyperchaotic behavior. To further demonstrate the practicability of nD-CTBCS, a reversible data hiding scheme is proposed for the secure communication of medical images. The experimental results show that the proposed method has higher security than the existing methods.

Docosahexaenoic acid (DHA) is an essential nutrient for humans and plays a critical role in human development and health. Freshwater fish, such as the common carp (Cyprinus carpio), have a certain degree of DHA biosynthesis ability and could be a supplemental source of human DHA needs. The elongase of very-long-chain fatty acid 5 (Elovl5) is an important enzyme affecting polyunsaturated fatty acid (PUFA) biosynthesis. However, the function and regulatory mechanism of the elovl5 gene related to DHA synthesis in freshwater fish is not clear yet. Previous studies have found that there are two copies of the elovl5 gene, elovl5a and elovl5b, which have different functions. Our research group found significant DHA content differences among individuals in Yellow River carp (Cyprinus carpio var.), and four candidate genes were found to be related to DHA synthesis through screening. In this study, the expression level of elovl5a is decreased in the high-DHA group compared to the low-DHA group, which indicated the down-regulation of elovl5a in the DHA synthesis pathways of Yellow River carp. In addition, using a dual-luciferase reporter gene assay, we found that by targeting the 3’UTR region of elovl5a, miR-26a-5p could regulate DHA synthesis in common carp. After CRISPR/Cas9 disruption of elovl5a, the DHA content in the disrupted group was significantly higher than in the wildtype group; meanwhile, the expression level of elovl5a in the disrupted group was significantly reduced compared with the wildtype group. These results suggest that elovl5a may be down-regulating DHA synthesis in Yellow River carp. This study could provide useful information for future research on the genes and pathways that affect DHA synthesis.

Coal mining leads to surface subsidence, landslides, soil erosion and other problems that seriously threaten the life and property safety of residents in mining areas, and it is urgent to obtain mining subsidence information using high-frequency, high-precision and large-scale monitoring methods. Therefore, this paper mainly studies the deformation monitoring of the Datong mining area using Lutan-1 monostatic and bistatic SAR data. Firstly, the latest Lutan-1 bistatic data are used to reconstruct the DSM, and the interferometric calibration method is used to improve the accuracy of the DSM. Then, the surface deformation monitoring of the mining area is implemented by using DInSAR, SBAS-InSAR and Stacking-InSAR with the reconstructed DSM data and Lutan-1 monostatic SAR data. Finally, the deformation monitoring results are compared with the surface deformation results based on the TanDEM data, and both the results are evaluated using the filed leveling data. Taking 20 images covering the Datong mining area as the data sources, the surface deformation results obtained using different InSAR methods in the mining area were quantitatively evaluated and analyzed. The results indicated that: (1) the DSM obtained using the Lutan-1 bistatic SAR data was assessed and demonstrated with the ICESat laser altimetry data an error of 2.8 m, which meets the Chinese 1:50,000 scale DEM cartographic accuracy standard, and the difference analysis with the TanDEM data shows that the terrain changes are mainly distributed in mountainous areas; (2) Due to the improvement in resolution, the registration accuracy of the SAR images and LT-DSM is higher than that of the TanDEM data in the range direction and azimuth direction; (3) Via evaluation with the filed leveling data, it is found that the surface deformation measurement results based on LT-DSM are less affected by terrain, and the accuracy of LT-DSM-SBAS and LT-DSM-DInSAR is improved by 11.5% and 16.3%, respectively, compared with TanDEM-SBAS and TanDEM-DInSAR, which demonstrates the effectiveness of the Lutan-1 bistatic and monostatic data for mine deformation monitoring.

Abstract Background Nucleolin (NCL, C23) is a multifunctional phosphoprotein that plays a vital role in modulating the survival, proliferationand apoptosis of cancer cells. However, the effects of NCL on cervical cancer and the underlying mechanisms behind this are poorly understood. Methods Lentiviral transfection technology was used to construct NCL knockdown cell lines. MTT, colony formation assays, and tumorigenic assays in vivo were performed to observe cell proliferation. HOECHST 33342 staining, flow cytometry, and caspase activity assay were used to test cell apoptosis. RNA‐Seq, Western blotting, and RT‐PCR were conducted to investigate the specific molecular mechanism. Results NCL knockdown inhibited cell proliferation and promoted apoptosis both in vivo and in vitro. Mechanistic studies revealed that NCL knockdown inhibited the PI3K/AKT pathway by upregulating FGF, ITGA, TNXB, VEGF, Caspase 3, and Bax, as well as by downregulating AKT, GNB4, CDK6, IL6R, LAMA, PDGFD, PPP2RSA and BCL‐2. In addition, the expression levels of apoptosis‐related genes after using a PI3K inhibitor LY294002 were consistent with shRNA studies, while treatment with a 740Y‐P agonist showed the opposite effect. Conclusions Our findings indicate that downregulation of NCL may be a novel treatment strategy forcervical cancer.

Drought is a major disaster over the Tibetan Plateau (TP) that exerts great impacts on natural ecosystems and agricultural production. Furthermore, most drought indices are only useful for assessing drought conditions on a coarse temporal scale. Drought indices that describe drought evolution at a fine temporal scale are still scarce. In this study, four machine learning methods, including random forest regression (RFR), k-nearest neighbor regression (KNNR), support vector regression (SVR), and extreme gradient boosting regression (XGBR), were used to construct daily drought indices based on multisource remote sensing and reanalysis data. Through comparison with in situ soil moisture (SM) over the TP, our results indicate that the drought index based on the XGBR model outperforms other models (R2 = 0.76, RMSE = 0.11, MAE = 0.08), followed by RFR (R2 = 0.74, RMSE = 0.11, MAE = 0.08), KNNR (R2 = 0.73, RMSE = 0.11, MAE = 0.08) and SVR (R2 = 0.66, RMSE = 0.12, MAE = 0.1). A new daily drought index, the standardized integrated drought index (SIDI), was developed by the XGBR model for monitoring agricultural drought. A comparison with ERA5-Land SM and widely used indices such as SPI-6 and SPEI-6 indicated that the SIDI depicted the dry and wet change characteristics of the plateau well. Furthermore, the SIDI was applied to analyze a typical drought event and reasonably characterize the spatiotemporal patterns of drought evolution, demonstrating its capability and superiority for drought monitoring over the TP. In addition, soil properties accounted for 59.5% of the model output, followed by meteorological conditions (35.8%) and topographic environment (4.7%).

Dietary copper supplementation in the feed of piglets generally exceeds 250–800 mg/kg, where a higher quantity (>250 mg/kg) can promote growth and improve feed conversion. Despite the reported positive effects, 90% of copper is excreted and can accumulate and pollute the soil. Data indicate that fungi have a biosorptive capacity for copper. Thus, the objectives of the present experiment were to study the effects of adding different strains of fungi on the biosorptive capacity for copper in swine manure and to evaluate potential effects on microbiota profiles. Aspergillus niger (AN), Aspergillus oryzae (AO), and Saccharomyces cerevisiae (SC) were selected, and each added 0.4% into swine manure, which contain 250 mg/kg of copper. The incubations lasted for 29 days, and biosorption parameters were analyzed on the 8th (D8), 15th (D15), 22nd (D22), and 29th (D29) day. Results showed that after biosorption, temperature was 18.47–18.77°C; pH was 6.33–6.91; and content of aflatoxin B1, ochratoxin A, and deoxynivalenol were low. In addition, residual copper concentration with AN was the lowest on D15, D22, and D29. The copper biosorption rate was also highest with AN, averaging 84.85% on D29. Biosorption values for AO reached 81.12% and for SC were lower than 80%. Illumina sequencing of 16S and ITS rRNA gene revealed that fungal treatments reduced the diversity and richness of fungal abundance, but had no effect on bacterial abundance. Unknown_Marinilabiliaceae, Proteiniphilum, Tissierella, and Curvibacter were the dominant bacteria, while Aspergillus and Trichoderma were the dominant fungi. However, the added strain of S. cerevisiae was observed to be lower than the dominant fungi, which contained less than 0.05%. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment predicted via PICRUSt2 that there were bacterial genes potentially related to various aspects of metabolism and environmental information processing. Overall, data indicated that Aspergillus can provide microbial materials for adsorption of copper.

Delftia tsuruhatensis has become an emerging pathogen in humans. There is scant information on the genomic characteristics of this microorganism. In this study, we determined the complete genome sequence of a clinical D. tsuruhatensis strain, TR1180, isolated from a sputum specimen of a female patient in China in 2019. Phylogenetic and average nucleotide identity analysis demonstrated that TR1180 is a member of D. tsuruhatensis. TR1180 exhibited resistance to β-lactam, aminoglycoside, tetracycline and sulphonamide antibiotics, but was susceptible to phenicols, fluoroquinolones and macrolides. Its genome is a single, circular chromosome measuring 6,711,018 bp in size. Whole-genome analysis identified 17 antibiotic resistance-related genes, which match the antimicrobial susceptibility profile of this strain, as well as 24 potential virulence factors and a number of metal resistance genes. Our data showed that Delftia possessed an open pan-genome and the genes in the core genome contributed to the pathogenicity and resistance of Delftia strains. Comparative genomics analysis of TR1180 with other publicly available genomes of Delftia showed diverse genomic features among these strains. D. tsuruhatensis TR1180 harbored a unique 38-kb genomic island flanked by a pair of 29-bp direct repeats with the insertion of a novel In4-like integron containing most of the specific antibiotic resistance genes within the genome. This study reports the findings of a fully sequenced genome from clinical D. tsuruhatensis, which provide researchers and clinicians with valuable insights into this uncommon species.

This paper studies the influence of the characteristics of the near-fault ground motion on the seismic responses of the structure with energy dissipation devices including soil-structure interaction (SSI). A ten-story reinforced concrete frame rested on soft site is introduced, and the viscous dampers added in the frame are designed. The numerical analysis method of the soil-structure system with viscous dampers is established through ANSYS program. In addition, the response spectra of the main characteristics of the near-fault ground motion, like hanging wall effect, velocity pulse-like effect, and forward-directivity effect, are investigated carefully to learn the features of spectra energy distribution. And then, the dynamic time-history analysis is performed on the SSI system with and without viscous dampers subjected to the selected near-fault ground motion. The study reveals that the seismic responses of the structure subjected to near-fault ground motion with hanging wall effect are obviously larger than those of the footwall effect, indicating the distinct hanging wall effects on the structural dynamic responses. In addition, the performance of the structure with viscous dampers is more influenced by the ground motion containing fling-step effect than that with forward-directivity effect. Moreover, the influence of the horizontal component of forward-directivity ground motion on the seismic responses of the structure is more obvious than that of parallel component ground motion. Consequently, the hanging wall effect, velocity pulse, and horizontal component in forward-directivity effect of the near-fault ground motion have distinct influence on the seismic responses of the structure with energy dissipation devices considering SSI effect, providing insight towards the performance-based seismic design of buildings rested at the near-fault sites considering the seismic SSI effect.

Bacterial resistance to antibiotics has become an important concern for public health. This study was aimed to investigate the characteristics and the distribution of the florfenicol-related resistance genes in bacteria isolated from four farms. A total of 106 florfenicol-resistant Gram-negative bacilli were examined for florfenicol-related resistance genes, and the positive isolates were further characterized. The antimicrobial sensitivity results showed that most of them (100, 94.33%) belonged to multidrug resistance Enterobacteriaceae. About 91.51% of the strains carried floR gene, while 4.72% carried cfr gene. According to the pulsed-field gel electrophoresis results, 34 Escherichia coli were subdivided into 22 profiles, the genetic similarity coefficient of which ranged from 80.3 to 98.0%. The multilocus sequence typing (MLST) results revealed 17 sequence types (STs), with ST10 being the most prevalent. The genome sequencing result showed that the Proteus vulgaris G32 genome consists of a 4.06-Mb chromosome, a 177,911-bp plasmid (pG32-177), and a 51,686-bp plasmid (pG32-51). A floR located in a drug-resistant region on the chromosome of P. vulgaris G32 was with IS91 family transposase, and the other floR gene on the plasmid pG32-177 was with an ISCR2 insertion sequence. The cfr gene was located on the pG32-51 flanked by IS26 element and TnpA26. This study suggested that the mobile genetic elements played an important role in the replication of resistance genes and the horizontal resistance gene transfer.

Abstract Background Florfenicol is a derivative of chloramphenicol that is used only for the treatment of animal diseases. A key resistance gene for florfenicol, floR, can spread among bacteria of the same and different species or genera through horizontal gene transfer. To analyze the potential transmission of resistance genes between animal and human pathogens, we investigated floR in Klebsiella pneumoniae isolates from patient samples. floR in human pathogens may originate from animal pathogens and would reflect the risk to human health of using antimicrobial agents in animals. Methods PCR was used to identify floR-positive strains. The floR genes were cloned, and the minimum inhibitory concentrations (MICs) were determined to assess the relative resistance levels of the genes and strains. Sequencing and comparative genomics methods were used to analyze floR gene-related sequence structure as well as the molecular mechanism of resistance dissemination. Results Of the strains evaluated, 20.42% (67/328) were resistant to florfenicol, and 86.96% (20/23) of the floR-positive strains demonstrated high resistance to florfenicol with MICs ≥512 μg/mL. Conjugation experiments showed that transferrable plasmids carried the floR gene in three isolates. Sequencing analysis of a plasmid approximately 125 kb in size (pKP18–125) indicated that the floR gene was flanked by multiple copies of mobile genetic elements. Comparative genomics analysis of a 9-kb transposon-like fragment of pKP18–125 showed that an approximately 2-kb sequence encoding lysR-floR-virD2 was conserved in the majority (79.01%, 83/105) of floR sequences collected from NCBI nucleotide database. Interestingly, the most similar sequence was a 7-kb fragment of plasmid pEC012 from an Escherichia coli strain isolated from a chicken. Conclusions Identified on a transferable plasmid in the human pathogen K. pneumoniae, the floR gene may be disseminated through horizontal gene transfer from animal pathogens. Studies on the molecular mechanism of resistance gene dissemination in different bacterial species of animal origin could provide useful information for preventing or controlling the spread of resistance between animal and human pathogens.

The selective laser melting (SLM) of o-Cr-Mo-W/316L composite with 10 wt% Co-Cr-Mo-W addition to 316L stainless steel (SS) powder is produced to explore it’s the corrosion behavior. The tensile experiment of SLM composites is also measured to investigate the difference between the two samples. The optimum parameters of SLM 316L SS and it’s composite samples are obtained by adjusting laser power and scanning speed with the relative density of 99.04 ± 0.69 and 99.15 ± 0.43. The yield strength of samples is increased from 731.96 MPa to 784.09 MPa after doping, and no obvious crack or fracture failure in the tensile samples are observed, indicating that the excellent plasticity is still maintained. The corrosion resistance of samples is improved largely with an order of magnitude lower corrosion current density than that of 316L SS and increasing of 277 mv of epit Ep. The addition of Cr element in the doped powder contributes to the formation of the passivated film containing Cr. The different pitting corrosion pit occurs mainly around the pre-existing pores of the powder and further extends outward to form pits with the increase of voltage.

Audiovisual integration significantly changes over the lifespan, but age-related functional connectivity in audiovisual temporal asynchrony integration tasks remains underexplored. In the present study, electroencephalograms (EEGs) of 27 young adults (22–25 years) and 25 old adults (61–76 years) were recorded during an audiovisual temporal asynchrony integration task with seven conditions [auditory (A), visual (V), AV, A50V, A100V, V50A and V100A]. We calculated the phase lag index (PLI)-weighted connectivity networks modulated by the audiovisual tasks and found that the PLI connections showed obvious dynamic changes after stimulus onset. In the theta (4–7 Hz) and alpha (8–13 Hz) bands, the AV and V50A conditions induced stronger functional connections and higher global and local efficiencies, reflecting a stronger audiovisual integration effect, which was attributed to the auditory information arriving at the primary auditory cortex earlier than the visual information reaching the primary visual cortex. Importantly, the functional connectivity and network efficiencies of old adults revealed higher global and local efficiencies and higher degree in both the theta and alpha bands. These larger network efficiencies indicated that old adults might experience more difficulties in attention and cognitive control during the audiovisual integration task with temporal asynchrony than young adults. There were significant associations between network efficiencies and peak time of integration only in young adults. We propose that an audiovisual task with multiple conditions might arouse the appropriate attention in young adults but would lead to a ceiling effect in old adults. Our findings provide new insights into the network topography of old adults during audiovisual integration and highlight higher functional connectivity and network efficiencies due to greater cognitive demand.

Similar to other CTX-M family enzymes, KLUC is a recently identified and emerging determinant of cefotaxime resistance that has been recovered from at least three Enterobacteriaceae species, including Kluyvera cryocrescens, Escherichia coli, and Enterobacter cloacae. Whether this extended-spectrum β-lactamase (ESBL) has been disseminated among commonly isolated Enterobacteriaceae is worthy of further investigation. In this study, we screened 739 nosocomial Enterobacteriaceae isolates (240 Klebsiella pneumoniae and 499 E. coli strains) and found that one K. pneumoniae and four E. coli isolates harbored the blaKLUC gene. Three blaKLUC determinants isolated from E. coli were entirely identical to a blaKLUC-3 gene previously recovered in the same hospital. PFGE of four blaKLUC-harboring E. coli strains showed that prevalence of these determinants was most likely mediated by horizontal gene transfer but not clonal dissemination. However, the variant isolated from K. pneumoniae belonged to a novel member of the KLUC enzyme group. This newly identified enzyme (KLUC-5) has an amino acid substitution compared with previously identified KLUC-1 (G18S) and KLUC-3 (G240D). Antimicrobial susceptibility tests showed that KLUC-5 significantly reduced resistance activity to almost all the selected antimicrobials compared to previously identified KLUC-3. Site-directed mutagenesis showed that blaKLUC-5-D240G and blaKLUC-5-S18G significantly enhanced the MIC against its best substrate. Conjugation and S1-PFGE indicated that blaKLUC-5 was located on a transferable plasmid, which was further decoded by single-molecule, real-time sequencing. Comparative genome analysis showed that its backbone exhibited genetic homology to the IncA/C incompatibility group plasmids. A transposable element, ISEcp1, was detected 256-bp upstream of the blaKLUC-5 gene; this location was inconsistent with the previously identified blaKLUC-1 but congruent with the variants recovered from E. coli in the same hospital. These data provide evidence of the increasingly emerging KLUC group of ESBLs in China.

In order to study the relationship between the structure and function of AmpG, structure, site-specific mutation, and gene complementary experiments have been performed against the clinical isolates of Pseudomonas aeruginosa. We found that there are 51 nucleotide variations at 34 loci over the ampG genes from 24 of 35 P. aeruginosa strains detected, of which 7 nucleotide variations resulted in amino acid change. The ampG variants with the changed nucleotides (amino acids) could complement the function of ampG deleted PA01 (PA01ΔG). The ampicillin minimum inhibitory concentration (MIC) of PA01ΔG complemented with 32 ampG variants was up to 512 μg/ml, similar to the original PA01 (P. aeruginosa PA01). Furthermore, site-directed mutation of two conservative amino acids (I53 and W90) showed that when I53 was mutated to 53S or 53T (I53S or I53T), the ampicillin MIC level dropped drastically, and the activity of AmpC β-lactamase decreased as well. By contrast, the ampicillin MIC and the activity of AmpC β-lactamase remained unchanged for W90R and W90S mutants. Our studies demonstrated that although nucleotide variations occurred in most of the ampG genes, the structure of AmpG protein in clinical isolates is stable, and conservative amino acid is necessary to maintain normal function of AmpG.

The aim of this study was to investigate the influences of different parameters on the performance of fiber reinforced polymer (FRP) masonry structures under debris flow using finite element models that were established using the software LS-DYNA. The overall structural responses under the impacts of viscous debris flows were analyzed based on an in-depth parametric study of some key factors (fiber types, relative impact positions, etc.). The results show that the diagonal and intersecting parallel types of FRP arrangements elicit better performances than horizontal types. Use of wider fiber cloths leads to the minimization of the structural response after its impact by debris flow. In addition, glass fiber reinforced polymer (GFRP) yields the best results among all studied materials in reducing local damage, while carbon fiber reinforced polymer (CFRP) yields a better overall structural response. Impact positions at the center of the wall are more unfavorable than those at the corners.

Many Pseudomonas aeruginosa virulence traits that contribute to human infections are accepted as being associated with its environmental lifestyle. Therefore, identifying the molecular mechanisms that govern the lifestyle choice is of high significance. We previously reported that a mutation in suhB results in a decrease in swimming motility and increased biofilm formation compared to the wild-type strain. Yet, little is known about how this occurs. In this study, we demonstrated that SuhB inversely regulates motility and biofilm formation through the GacA-RsmY/Z-RsmA cascade. Mutations in gacA or the two small RNAs rsmY/rsmZ, or overproduction of the RsmA protein essentially rescued the motility defect of the suhB mutant. Additionally, we identified a c-di-GMP mediated mechanism for SuhB regulation of motility and biofilm formation. We showed that the ΔsuhB mutant displayed elevated levels of c-di-GMP, and the ΔsuhB motility and biofilm phenotypes could be switched by artificially decreasing c-di-GMP levels. Further experiments led to the identification of the diguanylate cyclase GcbA responsible for regulating the c-di-GMP concentration in ΔsuhB and hence the switch between planktonic and surface-associated growth. Together, our results demonstrate a novel mechanism for SuhB regulation of the lifestyle transition via the Gac/Rsm and c-di-GMP signaling networks in P. aeruginosa.

Ti-6Al-4V alloys with different build orientations have been fabricated by selective laser melting (SLM). The corrosion behavior and mechanical properties have been studied. Investigation of microstructures were characterized by optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. Electrochemical results show that the vertical sample and horizontal sample possess excellent corrosion resistance in the cross section and longitudinal section respectively, which can be attributed to the presence of less acicular α′ martensite and more β phase. Mechanical properties of all samples were determined by compression testing and hardness measurements. The compression strength (σc) and plastic deformation (εp) of the horizontal sample were higher than those of the vertical sample and the sample with building direction of 45°, because the molten pool boundaries (MPBs) play a significant role in the microscopic slipping at the loading SLM parts. In addition, the sample with building orientation of 45° achieved highest hardness. Therefore, distinct anisotropy due to different build orientations.

AmpG is a transmembrane protein with permease activity that transports meuropeptide from the periplasm to the cytoplasm, which is essential for the induction of the ampC encoding β-lactamase. To obtain new insights into the relationship between AmpG structure and function, comparative genomics analysis, secondary and tertiary structure modeling, site-directed mutational analyses and genetic complementation experiments were performed in this study. AmpGs from different genera of bacteria (Escherichia coli, Vibrio cholerae and Acinetobacter baumannii) could complement AmpG function in Pseudomonas aeruginosa. The minimal inhibitory concentration (MIC) to ampicillin is 512 μg/ml for wild type strain PAO1, while it is 32 μg/ml for an ampG deletion mutant strain (PAO1ΔampG) with a corresponding decrease in the activity of the ampC-encoded β-lactamase. Site-directed mutagenesis of conserved AmpG residues (G29, A129, Q131 and A197) resulted in a loss of function, resulting in a loss of resistance to ampicillin in PAO1ΔampG. The G29A, G29V, A129T, A129V, A129D, A197S and A197D mutants had lower resistance to ampicillin and significantly decreased activity of the AmpC β-lactamase. The G29A, G29V, A129V, A197S and A197D mutants had decreased ampG mRNA transcript levels. The A129T and A129D mutants had normal ampG mRNA transcript levels, but the function of the protein was drastically reduced. Our experimental results demonstrate that the conserved amino acids played essential roles in maintaining the function of AmpG. Combined with the AmpG structural information, these critical amino acids can be targeted for the development of new anti-bacterial agents.

Polyurethane-steel sandwich structure, which creatively uses the polyurethane-steel sandwich composite as a structural material, is proposed to strengthen the impact resistance of buildings under debris flow. The impact resistance of polyurethane-steel sandwich structure under debris flow is investigated by a series of impact loading tests, compared with that of traditional steel frame structures. Additionally, further discussions regarding the hidden mechanism are performed. During the whole impact process, as for steel frame structure, the impacted column appeared obvious local deformation both at its column base and on the impact surface, leading to remarkable decrease of its impact resistance; while the stress and strain of polyurethane-steel sandwich structure develops more uniformly and distribute further in the whole structure, maintaining excellent integrity and impact transmission capability. The impact loading tests confirm that polyurethane-steel sandwich structure possesses superior impact resistance under debris flow. This is of great practical significance for the prevention and reduction of geological disasters.

The vibration control performance and its influencing factors of a tuned mass damper and a particle damper are examined by a single degree of freedom structure with such devices. The vibration control effects between these two dampers are also investigated. Increasing the mass ratio of the damper can improve the damping effects; under the condition of tuning frequency, the damping effects are remarkable. However, the more the deviation from the tuned frequency, the less controlling effects can be obtained. The damping effect of a particle damper is generally better than that of a tuned mass damper. For this test model, the particle damper can improve primary structure’s equivalent damping ratio 19 times to the original one’s, while the tuned mass damper can be 13 times. The reason lies in the fact that the particle damper can dissipate input energy by tuning mass, collision, impact, and friction between particles and the container and the momentum exchange effects between the secondary damper mass and the primary structure.

Plasmids are important antibiotic resistance determinant carriers that can disseminate various drug resistance genes among species or genera. By using a high throughput sequencing approach, two groups of plasmids of Escherichia coli (named E1 and E2, each consisting of 160 clinical E. coli strains isolated from different periods of time) were sequenced and analyzed. A total of 20 million reads were obtained and mapped onto the known resistance gene sequences. As a result, a total of 9 classes, including 36 types of antibiotic resistant genes, were identified. Among these genes, 25 and 27 single nucleotide polymorphisms (SNPs) appeared, of which 9 and 12 SNPs are nonsynonymous substitutions in the E1 and E2 samples. It is interesting to find that a novel genotype of bla(KLUC), whose close relatives, bla(KLUC-1) and bla(KLUC-2), have been previously reported as carried on the Kluyvera cryocrescens chromosome and Enterobacter cloacae plasmid, was identified. It shares 99% and 98% amino acid identities with Kluc-1 and Kluc-2, respectively. Further PCR screening of 608 Enterobacteriaceae family isolates yielded a second variant (named bla(KLUC-4)). It was interesting to find that Kluc-3 showed resistance to several cephalosporins including cefotaxime, whereas bla(KLUC-4) did not show any resistance to the antibiotics tested. This may be due to a positively charged residue, Arg, replaced by a neutral residue, Leu, at position 167, which is located within an omega-loop. This work represents large-scale studies on resistance gene distribution, diversification and genetic variation in pooled multi-drug resistance plasmids, and provides insight into the use of high throughput sequencing technology for microbial resistance gene detection.

A variety of innovative structural solutions have been recently introduced to mitigate damage and expedite the repair of buildings subjected to extreme seismic events, hence contributing to the urgent need for resilient societies. In this context, the present study experimentally and numerically investigates an innovative reinforced concrete (RC) shear wall (SW) structure with replaceable coupling beams (CBs) equipped with hybrid devices. These hybrid devices couple metallic and viscoelastic dampers and aim at satisfying multiple lateral load performances effectively. To assess the seismic performance of the proposed coupled SWsystem and verify the design principle, comparative shaking table tests were performed on two 1/4-scale seven-story SW structure specimens, including a conventional RC coupled SW and the proposed coupled SW with hybrid devices. The tests results indicate the improved performance of the proposed compared with the conventional system in terms of: (1) reduced interstory drifts and story accelerations demand under awide range of seismic intensities, (2) concentrated damage in the hybrid device and minimal damage to the other components contributing to the reparability of the structure. Furthermore, 3D finite element models for the shaking table test specimens were established in OpenSees and validated against experimental response. Successively, a numerical parametric study was conducted by performing non-linear response history analyses under a set of 22 ground motions to investigate the influence of different design configurations of the hybrid device on the peak interstory drifts and peak story accelerations. [ABSTRACT FROM AUTHOR]