The spread of antibiotic resistance genes (ARGs) has become an emerging threat to the global health. Although horizontal gene transfer (HGT) is regarded as one of the major pathways, more evidence ...has shown the significant involvement of vertical gene transfer (VGT). However, traditional cultivation-based methods cannot distinguish HGT and VGT, resulting in often contradictory conclusions. Here, single-cell microfluidics with time-lapse imaging has been successfully employed to dissect the contribution of plasmid-mediated HGT and VGT to ARG transmission in an environmental community. Using Escherichia coli with an ARG-coded plasmid pKJK5 with trimethoprim resistance as the donor, we quantified the effects of three representative antibiotics (trimethoprim, tetracycline and amoxicillin) on the ARG transfer process in an activated sludge bacterial community. It was found that HGT was influenced by the inhibitory mechanism of an antibiotic and its targets (donor, recipient alone or together), whereas VGT contributes significantly to the formation of transconjugants and consequently ARG spreading. Trimethoprim is highly resisted by the donor and transconjugants, and its presence significantly increased both the HGT and VGT rates. Although tetracycline and amoxicillin both inhibit the donor, they showed different effects on HGT rate as a result of different inhibitory mechanisms. Furthermore, we show the kinetics of HGT in a community can be described using an epidemic infection model, which in combination with quantitative measure of HGT and VGT on chip provides a promising tool to study and predict the dynamics of ARG spread in real-world communities.
•Dynamic plasmid transfer process was observed by cell tracking.•The dominancy of horizontal and vertical transfer pathways are difference.•Antibiotics stimulate and inhibit different aspects of plasmid transfer.•HGT was influenced by the inhibitory mechanism of an antibiotic and its targets.•Epidemic spread model can describe the kinetics of gene transmission via HGT.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•A facile synthesis method of MoS2/PANI intercalated nanocomposites is developed.•There is synergistic effect between PANI and MoS2 layer in the MoS2/PANI composites.•Intercalation is ...benefit for electrons transportation and conductivity increase.•The well-defined MoS2/PANI have good specific capacitances and long cyclic life.
High conductivity nanocomposites of molybdenum disulfide (MoS2)/polyaniline (PANI) were prepared via direct intercalation of aniline monomer and doped with dodecyl benzene sulfonic acid (DBSA). The intercalated interaction between PANI and MoS2 improves the conductivity and thermal stability of MoS2/PANI nanocomposites with the increasing fraction of MoS2. The conductivity and maximum weight loss velocity temperature of PANI/MoS2-38 sample are 2.38Scm−1 and 353°C, respectively. This architecture is also advantageous for enhancing the capacitance properties and cyclic stabilities of MoS2/PANI electrodes. In comparison to the specific capacitance of 131F/g and 42% retained capacitance over 600 cycles of PANI electrode, the MoS2/PANI-38 electrode provides a specific capacitance up to 390F/g and 86% retained capacitance over 1000 cycles. Thus it provides an improved capacitance method which synergistically combines pseudocapacitance and double-layer capacitance for supercapacitor electrodes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Simultaneous detection of multiple tumor biomarkers in body fluids could facilitate early diagnosis of lung cancer, so as to provide scientific reference for clinical treatment. This paper depicted a ...multi-parameter paper-based electrochemical aptasensor for simultaneous detection of carcinoembryonic antigen (CEA) and neuron-specific enolase (NSE) in a clinical sample with high sensitivity and specificity. The paper-based device was fabricated through wax printing and screen-printing, which enabled functions of sample filtration and sample auto injection. Amino functional graphene (NG)-Thionin (THI)- gold nanoparticles (AuNPs) and Prussian blue (PB)- poly (3,4- ethylenedioxythiophene) (PEDOT)- AuNPs nanocomposites were synthesized respectively. They were used to modify the working electrodes not only for promoting the electron transfer rate, but also for immobilization of the CEA and NSE aptamers. A label-free electrochemical method was adopted, enabling a rapid simple point-of-care testing. Experimental results showed that the proposed multi-parameter aptasensor exhibited good linearity in ranges of 0.01–500 ng mL−1 for CEA (R2 = 0.989) and 0.05–500 ng mL−1 for NSE (R2 = 0.944), respectively. The limit of detection (LOD) was 2 pg mL−1 for CEA and 10 pg mL−1 for NSE. In addition, the device was evaluated using clinical serum samples and received a good correlation with large electrochemical luminescence (ECL) equipment, which would offer a new platform for early cancer diagnostics, especially in those resource-limit areas.
•The aptasensor could enable simultaneous detection of two tumor markers in a single sample with high sensitivity.•The aptasensor had a fast response time as a label-free electrochemical detection method was adopted.•The aptasensor was fabricated by wax printing and screen-printing, which could be mass-produced easily with low cost.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Antimicrobial resistance (AMR) is a growing threat to human and animal health. Progress in molecular biology has revealed new and significant challenges for AMR mitigation given the immense diversity ...of antibiotic resistance genes (ARGs), the complexity of ARG transfer, and the broad range of omnipresent factors contributing to AMR. Municipal, hospital and abattoir wastewater are collected and treated in wastewater treatment plants (WWTPs), where the presence of diverse selection pressures together with a highly concentrated consortium of pathogenic/commensal microbes create favourable conditions for the transfer of ARGs and proliferation of antibiotic resistant bacteria (ARB). The rapid emergence of antibiotic resistant pathogens of clinical and veterinary significance over the past 80 years has re-defined the role of WWTPs as a focal point in the fight against AMR. By reviewing the occurrence of ARGs in wastewater and sludge and the current technologies used to quantify ARGs and identify ARB, this paper provides a research roadmap to address existing challenges in AMR control via wastewater treatment. Wastewater treatment is a double-edged sword that can act as either a pathway for AMR spread or as a barrier to reduce the environmental release of anthropogenic AMR. State of the art ARB identification technologies, such as metagenomic sequencing and fluorescence-activated cell sorting, have enriched ARG/ARB databases, unveiled keystone species in AMR networks, and improved the resolution of AMR dissemination models. Data and information provided in this review highlight significant knowledge gaps. These include inconsistencies in ARG reporting units, lack of ARG/ARB monitoring surrogates, lack of a standardised protocol for determining ARG removal via wastewater treatments, and the inability to support appropriate risk assessment. This is due to a lack of standard monitoring targets and agreed threshold values, and paucity of information on the ARG-pathogen host relationship and risk management. These research gaps need to be addressed and research findings need to be transformed into practical guidance for WWTP operators to enable effective progress towards mitigating the evolution and spread of AMR.
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•Wastewater treatment plays a crucial role in controlling AMR.•Molecular biology techniques can quantify ARG and identify ARB in wastewater system.•Keystone species of the AMR network and contributing factors can be mapped.•Revealing ARG-pathogen host relationships is essential to assess and monitor risk.•Future work to focus on ARG/ARB surrogates, thresholds and reporting units
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Gene transfer in biofilms is known to play an important role in antibiotic resistance dissemination. However, the process remains poorly understood. In this study, microfluidics with time-lapse ...imaging was used for real-time monitoring of plasmid-mediated horizontal gene transfer (HGT) in biofilms. Pseudomonas putida KT2440 harboring an antibiotic resistance plasmid RP4 was chosen as the donor while Escherichia coli and activated sludge bacteria were used as the recipient cells. Dynamic features of the transfer process, including the transfer rate, cell growth rate and kinetic changes of the transfer frequency, were determined. It was found that the routes for gene transfer strongly depend on the structure and composition of a biofilm. While intraspecies HGT is essential to initiate a transfer event, the secondary retransfer from transconjugants to the same species is more efficient and can cause cascading gene spread in single-strain biofilms. For the activated sludge biofilm, only small and scattered colonies formed and vertical gene transfer appears to be the dominant route after initial intraspecies transfer. Furthermore, more than 46% of genera in the activated sludge were permissive to plasmid RP4, many of which are associated with human pathogens. These phenomena imply early prevention and interruptions to biofilm structure could provide an effect way to inhibit rapid antibiotic resistance gene spread and reduce the likelihood of catastrophic events associated with antibiotic resistance.
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IJS, KILJ, NUK, PNG, UL, UM
It has great significance on the performance of cylinder liner-piston ring (CLPR) friction pairs with the different surface textures and affects the service life, reliability, and economy of diesel ...engines. However, most studies on the surface texture applied to CLPR have concentrated on simulated tests and computations, and the actual hot engine tests were ignored. The aim of this study was to gain insights into the interactions between different types of surface textures and the performance of diesel CLPRs under hot engine conditions. Three types of thread groove textures on cylinder liner surfaces with different widths, including 1, 2, and 3 mm, and a circular dimple texture on a piston ring with a depth of 100 μm were designed and machined, and were then tested under hot test conditions using a four-stroke diesel engine. To investigate the performance of diesel engine using different types of surface textures, the wear mass loss of the piston ring, worn surface morphologies and wear depth of the cylinder liner, exhaust gas emissions performance, and vibration performance of the diesel engine were obtained. Compared with untextured CLPRs, the experimental results indicated that appropriate surface texture (e.g., 3 mm wide grooved texture) significantly affected the comprehensive performance of the diesel engine. These findings will aid in understanding the performance impact of surface texture on diesel under hot engine conditions as well as its actual application to diesel engines.
•Surface texture improved the performances of diesel CLPR under hot engine tests condition.•Wear evaluation, emissions performance, and vibration performance of diesel CLPR was studied.•Experimental basis for improving the performance of CLPR on Marine engines was proposed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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