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•295 ARGs and MGEs were examined on a long time-scale.•The absolute abundance of ARGs and MGEs in the AS was peaked in spring.•The dominant and direct driver of ARG variation over ...time was revealed.•Clinical IntI1 can be adopted as an indicator to monitor the abundance of ARGs.•Clinical intI1 can be adopted as an indicator to monitor the removal of ARGs.
In this study, 295 antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) from the influent, activated sludge (AS), and membrane bioreactor (MBR) permeate were primarily examined in the wastewater treatment plant (WWTP) biweekly over 13 months. The absolute concentrations of ARGs and MGEs respectively ranged from 1.27 × 1010 to 1.94 × 1011 and 8.00 × 109 to 1.24 × 1011 copies/L in the influent, of which were reduced by 2 to 3 orders of magnitude in the permeate. No significant seasonal variation of ARGs and MGEs was found in the WWTP, except that the absolute abundance of ARGs and MGEs in the AS was peaked during spring. The antibiotics affected neither ARGs nor MGEs significantly, suggesting their concentrations may be not high enough to pose a selective pressure. In contrast, the bacterial community had direct effect on the MGEs variation, meanwhile the MGEs influenced the ARG abundance directly. Class 1 integron-integrase gene (intI1), clinical intI1, and Tn21 associated more frequently with ARGs in the AS over long-term, suggesting the potential of them involved in horizontal gene transfer. Both intI1 and clinical intI1 had significantly positive associations with the overall abundance of ARGs, as well as significantly negative relationships with the overall removal rates of ARGs in the MBR. However, the abundances between intI1 and clinical intI1 were significantly different. Meanwhile, clinical intI1 remained rather consistent proportion with the ARG abundance in the AS and permeate, was stronger correlated with human pathogens, and was associated with greater number of ARGs over time. Moreover, clinical intI1 was significantly associated with the removal efficiency of ARGs from all classes. Taken together, clinical intI1 can be adopted as an indicator for the abundance and removal efficiency of ARGs in the WWTP.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Methane production was inhibited at an influent OTC doses over 100 mg/L.•Resistome was enriched in anaerobic sludge in increasing OTC doses.•Remarkable multidrug resistance at the OTC 200 mg/L ...treatment.•Enhanced hydrolysis could remove the adverse effects of OTC to UASB.
In this study, two parallel-operated up-flow anaerobic sludge bed reactors, one used to treat synthetic wastewater spiked with oxytetracycline and the other used to treat the same wastewater after enhanced hydrolysis, were used to evaluate the impact of oxytetracycline on anaerobic digestion and resistance development and the efficacy of enhanced hydrolysis pretreatment on the elimination of adverse effects. The reactors were operated under a constant organic-loading rate (10 g/L/d) with increasing oxytetracycline doses (0 mg/L to 200 mg/L) over a period of 15 months. For the reactor without pretreatment, the chemical oxygen demand removal reached up to 89.5%%at oxytetracycline doses ranging from 0 mg/L to 100 mg/L, which collapsed at higher oxytetracycline doses. Miseq sequencing showed that a diverse hydrolysis/fermentation/acetogenesis bacterial community was maintained as the oxytetracycline dose was increased from 0 mg/L to 100 mg/L, while extreme dominance of Macellibacteroides (65.70%%- 71.56%) was found to occur at higher oxytetracycline doses. The total abundance of antibiotic resistance genes increased from 1.3 × 10−1 copies per cell to 2.6 × 10−1 copies per cell with increasing oxytetracycline dose from 0 mg/L to 5 mg/L, remained unchanged at oxytetracycline doses ranging from 25 mg/L to 100 mg/L, and then increased to 4.8 × 10−1 copies per cell and 1.3 copies per cell at oxytetracycline doses of 150 mg/L and 200 mg/L, respectively. Multidrug resistance developed in response to oxytetracycline treatment at 200 mg/L. Poor chemical oxygen demand removal and a marked enrichment in antibiotic resistance genes was validated using a full-scale up-flow anaerobic sludge bed system fed with an influent oxytetracycline concentration of approximately 200 mg/L. For the reactor treating wastewater pretreated with enhanced hydrolysis (85 °C for 6 h), the chemical oxygen demand removal rate and antibiotic resistance genes level over the whole oxytetracycline dose range were found to be similar to those achieved with zero oxytetracycline treatment. These results demonstrated that the control of conventional pollutants and ARGs could be achieved simultaneously in the UASB reactor by employing enhanced hydrolysis pretreatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•High-entropy rare-earth zirconate ceramics demonstrated extreme resistance to CMAS corrosion.•There are no horizontal and vertical cracks in the ceramic substrate and the reaction layer of the HEZ ...sample respectively.•The HEZ suffered from CMAS corrosion only through dissolution and re-precipitation, while additional grain boundary corrosion existed in the LZ.
The corrosion resistance to calcium-magnesium-alumino-silicates (CMAS) is critically important for the thermal barrier coatings (TBCs). High-entropy zirconate (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 (HEZ) ceramics with low thermal conductivity, high coefficient of thermal expansion and good durability to thermal shock is expected to be a good candidate for the next-generation TBCs. In this work, the CMAS corrosion of HEZ at 1300°C was firstly investigated and compared with the well-studied La2Zr2O7 (LZ). It is found that the HEZ ceramics showed a graceful behavior to CMAS corrosion, obviously much better than the LZ ceramics. The HEZ suffered from CMAS corrosion only through dissolution and re-precipitation, while additional grain boundary corrosion existed in the LZ system. The precipitated high-entropy apatite showed fine-grained structure, resulting in a reaction layer without cracks. This study reveals that HEZ is a promising candidate for TBCs with extreme resistance to CMAS corrosion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
easily produces drug-resistant mutants. A large number of mutational resistome genes exist in the genome of
. In this study, whole genome sequencing analysis of a multidrug-resistant
strain isolated ...by
antibiotic treatment showed a mutation in the
gene. Random mutagenesis of
was conducted and introduced into the PA14Δ
strain. Numerous CpxS mutants, including 14 different single amino acid substitutions, were identified, which led to reduced antibiotic susceptibility. Moreover, some of them were also present in the published genomes of
isolates. Around
, a gene coding for a putative sensor kinase, the nearest gene coding for a response regulator is
in the genome of
. Deletion of
restored antibiotic susceptibility in the above
mutant strains. As an extension of our previous work, where the expression of the
operon is directly activated by CpxR in
, in this study, we showed that the expression of the
promoter was increased in the above
mutant strains in a
-dependent manner, and
is prerequisite for the reduced antibiotic susceptibility. Therefore, we propose that the putative sensor kinase CpxS, together with CpxR, comprises a two-component regulatory system regulating the expression of the
operon in
. Our work indicates that
, as a novel member of mutational resistome, plays important roles on the development of multidrug resistance in
.
The purpose of this study was to explore how fast the thermophilic anaerobic microbial community could be established during the one-step startup of thermophilic anaerobic digestion from a mesophilic ...digester. Stable thermophilic anaerobic digestion was achieved within 20 days from a mesophilic digester treating sewage sludge by adopting the one-step startup strategy. The succession of archaeal and bacterial populations over a period of 60 days after the temperature increment was followed by using 454-pyrosequencing and quantitative PCR. After the increase of temperature, thermophilic methanogenic community was established within 11 days, which was characterized by the fast colonization of Methanosarcina thermophila and two hydrogenotrophic methanogens (Methanothermobacter spp. and Methanoculleus spp.). At the same time, the bacterial community was dominated by Fervidobacterium, whose relative abundance rapidly increased from 0 to 28.52 % in 18 days, followed by other potential thermophilic genera, such as Clostridium, Coprothermobacter, Anaerobaculum and EM3. The above result demonstrated that the one-step startup strategy could allow the rapid establishment of the thermophilic anaerobic microbial community.
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•A thermophilic anaerobic system was constructed rapidly by one-step startup strategy.•The thermophilic methanogenic archaeal community was rapidly established in 11 days.•Diverse thermophilic bacterial community played a role in stable thermophilic system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Resistance-Nodulation-Division (RND) efflux pumps are responsible for multidrug resistance in Pseudomonas aeruginosa. In this study, we demonstrate that CpxR, previously identified as a regulator of ...the cell envelope stress response in Escherichia coli, is directly involved in activation of expression of RND efflux pump MexAB-OprM in P. aeruginosa. A conserved CpxR binding site was identified upstream of the mexA promoter in all genome-sequenced P. aeruginosa strains. CpxR is required to enhance mexAB-oprM expression and drug resistance, in the absence of repressor MexR, in P. aeruginosa strains PA14. As defective mexR is a genetic trait associated with the clinical emergence of nalB-type multidrug resistance in P. aeruginosa during antibiotic treatment, we investigated the involvement of CpxR in regulating multidrug resistance among resistant isolates generated in the laboratory via antibiotic treatment and collected in clinical settings. CpxR is required to activate expression of mexAB-oprM and enhances drug resistance, in the absence or presence of MexR, in ofloxacin-cefsulodin-resistant isolates generated in the laboratory. Furthermore, CpxR was also important in the mexR-defective clinical isolates. The newly identified regulatory linkage between CpxR and the MexAB-OprM efflux pump highlights the presence of a complex regulatory network modulating multidrug resistance in P. aeruginosa.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•The multicollinearity among traditional input variables of cooling load predictions is proven.•PCA is applicable to avoid multicollinearity and improve prediction accuracy.•Including CEHT as an ...input variable is an effective way to improve prediction accuracy.•Dynamic two-step correction is proposed and is proven to be an effective way to improve prediction accuracy.•Dynamic model building is proven to be an effective measure to improve prediction accuracy.
The cooling load prediction of heating, ventilating and air-conditioning (HVAC) systems in office buildings is fundamental work for optimizing the operation of HVAC systems. In this paper, an improved multivariable linear regression model is proposed to predict the daily mean cooling load of office buildings in which three main measures, including the principal component analysis (PCA) of meteorological factors, cumulative effect of high temperature (CEHT) and dynamic two-step correction, are used to improve prediction accuracy. The site measured cooling load of two office buildings in Tianjin is used to validate the model and evaluate the prediction accuracy. Meanwhile, four contrast models with one or two of the three measures are also built. A comparison among the models proves that a combination of the three measures could effectively improve the prediction accuracy. The predicted load of the proposed model has acceptable agreement with actual load, where the mean absolute relative error is less than 8%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
► We establish a safety evaluation and early warning rating system for hot and humid environments. ► We adopt fuzzy AHP based on trapezoidal fuzzy numbers for the safety evaluation. ► The safety ...grade and early warning grade are determined. ► The results demonstrate the engineering practicability and effectiveness of this method.
Hot and humid environments are prevalent in many industries. People working in hot and humid environments are at great risk of specific heat-related disorders, the productivity decrease and safety problems. In order to guarantee workers’ health and safety, safety evaluation and early warning rating of the hot and humid environments are studied in this paper. The fuzzy analytic hierarchy process (AHP) method is proposed to evaluate the work safety in hot and humid environments. Trapezoidal fuzzy numbers are adopted to handle inherent uncertainty and imprecision of the data involved in decision process. Within the proposed methodology, a decision group is firstly established. A safety evaluation framework containing three factors (work, environment, and workers) and ten sub-factors are established. The fuzzy weights of the factors and sub-factors are calculated based on the pair-wise comparisons. Then the fuzzy evaluating vectors of the sub-factors and factors can be calculated according to the initial evaluation data. Therefore, the comprehensive safety index, safety grade and early warning grade can be determined. An example is given to demonstrate the proposed method. The results demonstrate the engineering practicability and effectiveness of this method in extreme environment evaluation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Re-engineering of complex biological systems (CBS) is an important goal for applications in synthetic biology. Efforts have beenmade to simplify CBS by refactoring a large number of genes with ...rearranged polycistrons and synthetic regulatory circuits. Here, a posttranslational protein-splicing strategy derived from RNA viruses was exploited to minimize gene numbers of the classic nitrogenase system, where the expression stoichiometry is particularly important. Operon-based nif genes from Klebsiella oxytoca were regrouped into giant genes either by fusing genes together or by expressing polyproteins that are subsequently cleaved with Tobacco Etch Virus protease. After several rounds of selection based on protein expression levels and tolerance toward a remnant C-terminal ENLYFQ-tail, a system with only five giant genes showed optimal nitrogenase activity and supported diazotrophic growth of Escherichia coli. This study provides an approach for efficient translation from an operon-based system into a polyprotein-based assembly that has the potential for portable and stoichiometric expression of the complex nitrogenase system in eukaryotic organisms.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
In the present study, a set of experiments were accomplished to appraise the thermal performance and heat transfer of
n
-pentane-acetone and
n
-pentane-methanol mixtures inside a gravity-assisted ...thermosyphon heat pipe. Pure
n
-pentane, acetone and methanol were also tested as the carrying fluid to produce some reference data. The heat pipe was manufactured from copper with length and diameter of 290 and 20 mm, respectively. The effect of multiple factors covering the input heat to the evaporator section, the filling ratio of the carrying fluid, heat pipe tilt angle and also the type of the carrying fluid on temperature distribution and thermal performance of the heat pipe was investigated. The results demonstrated that the thermo-physical properties of the carrying fluid were the key factor controlling the heat pipe efficiency. The vapour pressure and boiling temperature of the carrying fluid controlled the thermal efficiency of the system such that for
n
-pentane-acetone, the highest thermal efficiency was obtained. Also, it was identified that the filling ratio of the system is a key operating factor such that the value of the filling ratio was small for the evaporative carrying fluid (binary mixtures), while it was large for the non-evaporative carrying fluids. Also, heat pipe tilt angle was impressed by the type of the carrying fluid; the optimum tilt angle was 55 degree for the binary mixtures, while it was 65° for the pure liquids.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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