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Background. Carbapenemase-producing Klebsiella pneumoniae (CP-Kp) poses distinct clinical challenges due to extensively drug resistant (XDR) phenotype, and sequence type (ST) 11 is the most dominant blaKPC-2-bearing CP-Kp clone in China. The purpose of this current retrospective study was to explore the genetic factors associated with the success of XDR CP-Kp ST11 strains circulated in the intensive care unit (ICU) of a Chinese tertiary hospital. Methods. Six ST11 XDR CP-Kp strains were identified between May and December 2014 and validated by minimum inhibitory concentration examination, polymerase chain reaction, and pyrosequencing. The six ST11 XDR CP-Kp, as well as three multi-drug resistant (MDR) and four susceptible strains, were sequenced using single-molecule real-time method. Comprehensively structural and functional analysis based on comparative genomics was performed to identify genomic characteristics of the XDR ST11 CP-Kp strains. Results. We found that ST11 XDR blaKPC-2-bearing CP-Kp strains isolated from inpatients spread in the ICU of the hospital. Functionally, genes associated with information storage and processing of the ST11 XDR CP-Kp strains were more abundant than those of MDR and susceptible strains, especially genes correlative with mobile genetic elements (MGEs) such as transposons and prophages. Structurally, eleven large-scale genetic regions taken for the unique genome in these ST11 XDR CP-Kp strains were identified as MGEs including transposons, integrons, prophages, genomic islands, and integrative and conjugative elements. Three of them were located on plasmids and eight on chromosomes; five of them were with antimicrobial resistance genes and eight with adaptation associated genes. Notably, a new blaKPC-2-bearing ΔΔTn1721-blaKPC-2 transposon, probably transposed and truncated from ΔTn1721-blaKPC-2 by IS903D and ISKpn8, was identified in all six ST11 XDR CP-Kp strains. Conclusion. Our findings suggested that together with clonal spread, MGEs identified uniquely in the ST11 XDR CP-Kp strains might contribute to their formidable adaptability, which facilitated their widespread dissemination in hospital.

Solar-driven production of hydrogen peroxide (H

Graphene with low oxygen content via an electrochemically anode exfoliation is desired. Here, an electrochemical exfoliation method to realize the simultaneous electrochemical preparation and reduction of graphene with low oxygen content is proposed using a flexible graphite sheet (FGS). Under water bath, the FGS is soaked into a NaBH4 solution under an electric field of 3 V/cm for 3, 9, 15 or 21 h (Gr-3/Gr-9/Gr-15/Gr-21). The C/O ratios of the FGS, Gr-3, Gr-9, Gr-15 and Gr-21 increase in turn by the X-ray photoelectron spectroscopy. The comparison between the electrochemical properties of the FGS, Gr-3, Gr-9, Gr-15 and Gr-21 indicates that the Gr-15 possesses a specific capacitance of 181 F/g and capacitance retention of 93.8% over 3000 cycles, which shows better electrochemical performances than the FGS, Gr-3, Gr-9 and Gr-21. The symmetric supercapacitor based on the Gr-15 achieves an energy density as high as 22.56 Wh/kg at a power density of 0.85 kW/kg.

A series of high temperature superconducting (HTS) flux pumps have been developed to achieve the persistent current mode (PCM) operation for HTS magnets. However, most of the HTS flux pumps work with a small operating air gap, or with an iron core, the extra heat load brought by the conventional components deployed in the cryogenic environment is inevitable. To address this problem, in this study, in conjunction with the wireless power transfer (WPT) approach and transformer-rectifier type HTS flux pump, we have proposed a contactless self-regulating HTS flux pump. A circuit model and a 2D H-formulation finite-element model have been built for better understanding this system. Furthermore, a basic prototype was proposed to experimentally validate this concept. The measured results indicate that this method has the potential to charge the HTS magnet with all the conventional constituents outside the cryostat, and the operating frequency could be very low to evade inducing large eddy current as well as losses on the cryostat wall.

In order to charge the superconducting magnets, the means of current leads has been utilized widely. Nevertheless, due to the losses in high-temperature superconducting (HTS) magnets, the need for compensating the current decay periodically promotes the development of HTS flux pumps. Among them, transformer-rectifier type flux pump grabs attention owing to the simple rectifying component. However, it is the principle of bridge rectifying that may lead to an unavoidable induced direct current which self-evidently would make a negative impact on the charging speed. To this regard, this paper proposed the means of combining the current-controlled transformer-rectifier type flux pump with a secondary resistor to achieve an improved charging performance. With a verification experiment carried out, it was confirmed that the proposed method is viable. And there exists an optimal resistance -0.9 mΩ, which is essential to speed the charging progress up.

The rational design of highly active and stable atomically dispersed M-X4 (M = Fe, Co, Ni, etc., X = C, N) -based catalysts holds promises for wide application in almost all realms of catalysis. Despite great effort in the construction of specific M-X4 centers, the possible effect of non-coordinated heteroatoms on the catalytic activity of metal centers has been rarely explored. Herein, we develop a new type of M-X4 catalyst composed of Fe-N4 centers and non-coordinated B heteroatoms (FeNC+B) and find the key role of non-coordinated B adjacent to Fe-N4 centers in tailoring their electron density and final catalytic selectivity. The experimental and theoretical results demonstrated that non-coordinated boron atoms could decrease the electron density of Fe-N4 centers to a suitable level and thus boost the selective production of nitriles from amine oxidation by depressing the formation of imines due to the flattened energy barrier of the reversible conversion of imines back to amines. As a reusable heterocatalyst, the state-of-the-art FeNC+B catalyst provides a turn-over frequency (TOF) value of 21.6 molbenzonitrile·molFe−1·h−1 (100 °C), outpacing that of bench-marked nonnoble-metal-based homogeneous catalyst by a factor of 3.4.

Background Opportunistic pathogens are important for clinical practice as they often cause antibiotic-resistant infections. However, little is documented for many emerging opportunistic pathogens and their biological characteristics. Here, we isolated a strain of extended-spectrum β-lactamase-producing Enterobacteriaceae from a patient with a biliary tract infection. We explored the biological and genomic characteristics of this strain to provide new evidence and detailed information for opportunistic pathogens about the co-infection they may cause. Results The isolate grew very slowly but conferred strong protection for the co-infected cephalosporin-sensitive Klebsiella pneumoniae. As the initial laboratory testing failed to identify the taxonomy of the strain, great perplexity was caused in the etiological diagnosis and anti-infection treatment for the patient. Rigorous sequencing efforts achieved the complete genome sequence of the isolate which we designated as AF18. AF18 is phylogenetically close to a few strains isolated from soil, clinical sewage, and patients, forming a novel species together, while the taxonomic nomenclature of which is still under discussion. And this is the first report of human infection of this novel species. Like its relatives, AF18 harbors many genes related to cell mobility, various genes adaptive to both the natural environment and animal host, over 30 mobile genetic elements, and a plasmid bearing blaCTX-M-3 gene, indicating its ability to disseminate antimicrobial-resistant genes from the natural environment to patients. Transcriptome sequencing identified two sRNAs that critically regulate the growth rate of AF18, which could serve as targets for novel antimicrobial strategies. Conclusions Our findings imply that AF18 and its species are not only infection-relevant but also potential disseminators of antibiotic resistance genes, which highlights the need for continuous monitoring for this novel species and efforts to develop treatment strategies.

A stable artificial solid electrolyte interphase (ASEI) containing phosphazene and perfluoroalkoxy groups was designed to protect Li anodes. The ASEI with high ionic conductivity and mechanical robustness successfully suppressed the growth of Li dendrites, significantly enhancing the electrochemical performance of the Li-O2 batteries.

Biomass burning (BB) is an important source of carbonaceous aerosols in Northeast China (NEC). Quantifying the original contribution of BB to organic carbon (OC) [BB-OC] can provide an essential scientific information for the policy-makers to formulate the control measures to improve the air quality in the NEC region. Daily PM2.5 samples were collected in the rural area of Changchun city over the NEC region from May 2017 to May 2018. In addition to carbon contents, BB tracers (e.g., levoglucosan and K+BB, defined as potassium from BB) were also determined, in order to investigate the relative contribution of BB-OC. The results showed that OC was the dominant (28%) components of PM2.5 during the sampling period. Higher concentrations of OC, levoglucosan, and K+BB were observed in the autumn followed by the winter, spring, and summer, indicating that the higher BB activities during autumn and winter in Changchun. By using the Bayesian mixing model, it was found that burning of crop residues were the dominant source (65-79%) of the BB aerosols in Changchun. During the sampling period, the aging in air mass (AAM) ratio was 0.14, indicating that ~86% of levoglucosan in Changchun was degraded. Without considering the degradation of levoglucosan in the atmosphere, the BB-OC ratios were 23%, 28%, 7%, and 4% in the autumn, winter, spring, and summer, respectively, which were 1.4-4.8 time lower than those (14-42%) with consideration of levoglucosan degradation. This illustrated that the relative contribution of BB to OC would be underestimated (~59%) without considering degradation effects of levoglucosan. Although some uncertainty was existed in our estimation, our results did highlight that the control of straw burning was an efficient way to decrease the airborne PM2.5, improving the air quality in the NEC plain.

The activation of C–H bonds is a central challenge in organic chemistry and usually a key step for the retro-synthesis of functional natural products due to the high chemical stability of C–H bonds. Electrochemical methods are a powerful alternative for C–H activation, but this approach usually requires high overpotential and homogeneous mediators. Here, we design electron-deficient W2C nanocrystal-based electrodes to boost the heterogeneous activation of C–H bonds under mild conditions via an additive-free, purely heterogeneous electrocatalytic strategy. The electron density of W2C nanocrystals is tuned by constructing Schottky heterojunctions with nitrogen-doped carbon support to facilitate the preadsorption and activation of benzylic C–H bonds of ethylbenzene on the W2C surface, enabling a high turnover frequency (18.8 h−1) at a comparably low work potential (2 V versus SCE). The pronounced electron deficiency of the W2C nanocatalysts substantially facilitates the direct deprotonation process to ensure electrode durability without self-oxidation. The efficient oxidation process also boosts the balancing hydrogen production from as-formed protons on the cathode by a factor of 10 compared to an inert reference electrode. The whole process meets the requirements of atomic economy and electric energy utilization in terms of sustainable chemical synthesis. Designing electrode materials for mild and additive-free activation of C–H bonds is of great challenge. The authors report the application of electron-deficient W2C nanocrystal electrodes to boost the dissociation of C-H bonds toward the efficient alkoxylation and hydrogen evolution reactions.

M1 polarization of macrophages is an important pathological process in myocardial ischemia reperfusion injury, which is the major obstacle for the treatment of acute myocardial infarction. Currently, the strategies and mechanisms of inhibiting M1 polarization are poorly explored. This study aims to investigate the role of soluble death receptor 5-Fc (sDR5-Fc) in regulating M1 polarization of macrophages under extreme conditions and explore the mechanisms from the aspect of glycolysis.Extreme conditions were induced in RAW264.7 cells. Real-time quantitative polymerase chain reaction and western blot were used to detect the expression of mRNA and proteins, respectively. Cell counting kit-8 was used to investigate the proliferation activity of cells. Expression levels of inflammatory cytokines were determined by enzyme-linked immunosorbent assay.We found that sDR5-Fc rescues the proliferation of macrophages under extreme conditions, including nutrition deficiency, excessive peroxide, and ultraviolet irradiation. In addition, administration of sDR5-Fc inhibits the M1 polarization of macrophages induced by lipopolysaccharide (LPS) and interferon-gamma (IFN-γ), as the expression of M1 polarization markers CD86, CXC motif chemokine ligand 10, matrix metalloproteinase 9, and tumor necrosis factor-α, as well as the secretion of inflammatory factors interleukin (IL)-1β and IL-6, were significantly decreased. By further investigation of the mechanisms, the results showed that sDR5-Fc can recover the LPS and IFN-γ induced pH reduction, lactic acid elevation, and increased expression of hexokinase 2 and glucose transporter 1, which were markers of glycolysis in macrophages.sDR5-Fc inhibits the M1 polarization of macrophages by blocking the glycolysis, which provides a new direction for the development of strategies in the treatment of myocardial ischemia reperfusion injury.

The traditional NH3 production method (Haber-Bosch process) is currently complemented by electrochemical synthesis at ambient conditions, but the rather low selectivity (as indicated by the Faradaic efficiency) for the electrochemical reduction of molecular N2 into NH3 impedes the progress. Here, we present a powerful method to significantly boost the Faradaic efficiency of Au electrocatalysts to 67.8% for the nitrogen reduction reaction (NRR) by increasing their electron density through the construction of inorganic donor-acceptor couples of Ni and Au nanoparticles. The unique role of the electron-rich Au centers in facilitating the fixation and activation of N2 was also investigated via theoretical simulation methods and then confirmed by experimental results. The highly coupled Au and Ni nanoparticles supported on nitrogen-doped carbon are stable for reuse and long-term performance of the NRR, making the electrochemical process more sustainable for practical application.

Due to the local emissions and transportations of air pollution from the most polluted regions such as the North China Plain and Yangtze Delta metropolitan, Xuzhou is becoming one of the most polluted cities in East China. The sources and formation processes of nitrogen-containing aerosols are therefore very complex. Two continuous aerosol measurement campaigns were conducted in this industrial city during the wintertime and summertime of 2016, to investigate the chemical compositions and potential sources of total nitrogen (TN, including 89% inorganic nitrogen and 11% organic nitrogen) in PM2.5. Abrupt enhancements of nitrogen-containing aerosols (e.g., NO3− and NH4+) were found in the winter, and nitrate became as a dominant contributor in high pollution days (e.g., PM2.5 > 150 μg m−3). Nitrogen oxidation ratios (NOR) correlated significantly with aerosol liquid water content (ALWC), which was estimated by ISORPROPIA-II model. This suggested heterogeneous process might be an important pathway in nitrate formation during the high PM2.5 days. The nitrogen isotope composition (δ15N) in TN varied from −1.3 to +13.2‰ with a mean value of 6.9 ± 3.6‰ during the wintertime. An isotope-based source apportionment approach was then developed using a Bayesian isotope mixing model (SIAR) with chemical compositions as an important constrain, which improved accuracy and reduced the overall uncertainties in estimations of TN sources. From this optimized model, we identified six major sources including NH3 from combustion-related emissions (49%), NH3 derived from animal wastes (6%), NH3 from urban volatilization (3%), NOx derived from coal combustion (33%), NOx from biomass burning (5%) and NOx from vehicles (3%). Our results demonstrated that ambient NOx was dominated by coal combustion. Since NOx and NH3 are important precursors for ammonium nitrate aerosols, controlling of combustion related NOx and NH3 emissions might be an important way to reduce PM2.5 levels in this region.

Several conditions of two-step chemical reduction method for simultaneously determination of stable nitrogen and oxygen isotope compositions in atmospheric nitrate (NO3−) particles, such as the pH, reaction time, type of cadmium powder and concentration of NaCl, were optimized. The nitrite (NO3−) in the samples was reduced to nitrous oxide (N2O) through the improved method and the produced N2O was measured for their isotope compositions (δ15N and δ18O) by coupling an autosampler and a pre-concentration device with the MAT253 isotope ratio mass spectrometer. The standard curves of the nitrogen (R2 = 0.9999) and oxygen (R2 = 0.9996) isotope ratios of N2O and NO3− were established by measuring the international standards with known isotope ratios, and the nitrogen and oxygen isotope ratio of nitrates of the sample could be therefore converted. The principle of this method was clear, and only required very small amounts of samples (i.e., 0.8 μg of N). The standard deviations of δ15N and δ18O were 0.08‰ and 0.24‰, respectively. This method was not only suitable for atmospheric aerosol samples, but also for the other environmental samples such as rainwater and snow samples with low concentrations. This study provided a novel method for better understanding emission sources and transformation pathways of atmospheric nitrate.

A stronger, cooler wood One good way to reduce the amount of cooling a building needs is to make sure it reflects away infrared radiation. Passive radiative cooling materials are engineered to do this extremely well. Li et al. engineered a wood through delignification and re-pressing to create a mechanically strong material that also cools passively. They modeled the cooling savings of their wood for 16 different U.S. cities, which suggested savings between 20 and 50%. Cooling wood would be of particular value in hot and dry climates. Science , this issue p. 760

With the advancement in sub-ambient cooling of water during daytime under the sun with scalable-manufactured radiative cooling metamaterials, the challenge for applications lies in design and building of large-scale radiative cooling systems. Here, we present a kW-scale, 24-hour continuously operational, radiative sky cooling system, with both experimental study and detailed modeling. We first quantitatively show how water flow rate directly affects the system cooling power and inversely affects the water temperature drop. A day-and-night stagnant (flow rate = 0 L/(min·m2)) water cooling test of the system shows a consistent sub-ambient water temperature drop of 5–7 °C. A daytime cooling test of the system at a low flow rate of 0.227 L/(min·m2) yields a maximum sub-ambient temperature drop of 4.0 °C with an average net cooling power of around 80 W/m2. Further modelling for a typical metrological year (in Phoenix, Arizona) shows that the system could generate as much as 350 kWh cold (or 26 kWh/m2) with a sub-ambient temperature drop of 4–5 °C at a low flow rate of 0.1 L/(min·m2) during a typical summer month. The cold generated could be used to assist AC systems in regions or seasons with high ambient temperatures.

Singlet oxygen as an activated oxygen species played an important role in organic synthesis. Suitable catalyst for converting ubiquitous oxygen molecule to singlet oxygen under mild conditions has attracted a wide range of attention. Herein, carbon dots have been confined into mesopores of silicalite-1 nanocrystals framework and acted as active sites for generation of singlet oxygen. The high oxygen-adsorption capacity of zeolite nanocrystals facilitated the photocatalytic generation rate of singlet oxygen, outpacing the free-standing carbon dots for 14-fold. The integrated carbon dot-zeolite nanocrystal hybrid also exhibited a special size-dependent selectivity for organic synthesis by using the in situ formed and confined singlet oxygen as active oxygen species.

We described an effective way to generate a Co3O4 mesocrystal array with well-developed porosity, simply by uniting a coupled interface with hydrazine treatment. Due to the fast electron transfer and sufficient active sites, the Ti mesh-supported Co3O4 nanoneedles electrode could provide a current density of 49.9 mA cm−2 at 570 mV OER overpotential and has exceptionally high stability.

Summary Real-world applications of radiative sky cooling require thoughtful design of the system, along with clear understanding of weather effects on system performance. This work explores application of radiative sky cooling based upon a low-cost radiative cooling metamaterial that can be scalably manufactured. A radiative cooled-cold collection (RadiCold) module is developed to cool water to 10.6°C below ambient at noon under stationary conditions. The effects of different weather conditions (wind speed, precipitable water, and cloud cover) on the performance of radiative cooling have been investigated. A kilowatt (kW)-scale RadiCold system with 13.5 m2 radiative cooling surface area is then built and demonstrated to provide a maximum cooling power of 1,296 W at night, and an average cooling power of 607 W at noon (12–2 p.m.) under 952 W/m2 average solar irradiance at 26.5 L/(h⋅m2) volumetric flow rate. A building-integrated RadiCold system is proposed to provide continuous day-and-night cooling.

The activation of C–H bonds is a central challenge in organic chemistry and usually a key step for the retro-synthesis of functional natural products due to the high chemical stability of C–H bonds. Electrochemical methods are a powerful alternative for C–H activation, but this approach usually requires high overpotential and homogeneous mediators. Here, we design electron-deficient W2C nanocrystal-based electrodes to boost the heterogeneous activation of C–H bonds under mild conditions via an additive-free, purely heterogeneous electrocatalytic strategy. The electron density of W2C nanocrystals is tuned by constructing Schottky heterojunctions with nitrogen-doped carbon support to facilitate the preadsorption and activation of benzylic C–H bonds of ethylbenzene on the W2C surface, enabling a high turnover frequency (18.8 h−1) at a comparably low work potential (2 V versus SCE). The pronounced electron deficiency of the W2C nanocatalysts substantially facilitates the direct deprotonation process to ensure electrode durability without self-oxidation. The efficient oxidation process also boosts the balancing hydrogen production from as-formed protons on the cathode by a factor of 10 compared to an inert reference electrode. The whole process meets the requirements of atomic economy and electric energy utilization in terms of sustainable chemical synthesis., Designing electrode materials for mild and additive-free activation of C–H bonds is of great challenge. The authors report the application of electron-deficient W2C nanocrystal electrodes to boost the dissociation of C-H bonds toward the efficient alkoxylation and hydrogen evolution reactions.

Stille cross-coupling reactions catalysed by an ideal catalyst combining the high activity of homogeneous catalysts and the reusability of heterogeneous catalysts are of great interest for C-C bond formation, which is a widely used reaction in fine chemistry. Despite great effort to increase the utilization ratio of surface metal atoms, the activity of heterogeneous catalysts under mild conditions remains unsatisfactory. Herein, we design a proof-of-concept strategy to trigger the room-temperature activity of heterogeneous Au catalysts by decreasing the electron density at the interface of a rationally designed Schottky heterojunction of Au metals and boron-doped carbons. The electron-deficient Au nanoparticles formed as a result of the rectifying contact with boron-doped carbons facilitate the autocleavage of C-Br bonds for highly efficient C-C coupling reactions of alkylbromides and allylstannanes with a TOF value of 5199 h-1 at room temperature, surpassing that of the state-of-the-art homogeneous catalyst.

A stable artificial solid electrolyte interphase (ASEI) containing phosphazene and perfluoroalkoxy groups was designed to protect Li anodes. The ASEI with high ionic conductivity and mechanical robustness successfully suppressed the growth of Li dendrites, significantly enhancing the electrochemical performance of the Li-O2 batteries.

In this study, 30 PM

To investigate the effect of biomass burning in Changchun in autumn on the absorbance of water-soluble organic carbon (WSOC) on PM

Opportunistic pathogens are important for clinical practice as they often cause antibiotic resistant infections. However, little is documented for many emerging opportunistic pathogens and their biological characteristics. Here, we isolated a novel species of extended-spectrum β-lactamase-producing Enterobacteriaceae from a patient of biliary tract infection. The isolate grows very slowly but confers strong protection for the co-infected cephalosporin-sensitive Klebsiella pneumonia. As the initial laboratory testing failed to identify the taxonomy of the strain, great perplexity was caused in the etiological diagnosis, and anti-infection treatment for the patient. Rigorous sequencing efforts achieved the complete genome sequence of the isolate which we designated as AF18. AF18 is phylogenetically close to a few strains respectively isolated from soil, clinical sewage, and patients, forming a novel species together, while the taxonomic nomenclature of which is still under discussion. And this is the first report of human infection of this novel species. As its relatives, AF18 harbors many genes related to cell mobility, various genes adaptive to both wild environment and animal host, tens of genetic mobile elements, and a plasmid bearing blaCTX-M-3 gene, indicating its ability to disseminate antimicrobial resistant genes from wild to patients. Transcriptome sequencing identified two sRNAs that critically regulate the growth rate of AF18 which could serve as targets for novel antimicrobial strategies. These findings imply that AF18 and its species are not only infection-relevant but also potential disseminators in transferring antibiotic determinants, which highlights the need for continuous monitoring for this novel species and efforts to develop controlling strategies.

As a new type of heterogeneous catalyst with "homogeneous-like" activity, single-site transition-metal materials are usually treated as integrated but separate active centers. A novel grouping effect is reported for single Ni-N4 sites in nitrogen-doped carbon (Ni/NC), where an effective ligand-stabilized polycondensation method endows Ni/NC nanocatalysts with a high content of single-site Ni up to 9.5 wt %. The enhanced electron density at each single Ni-N4 site promotes a highly efficient hydrogen transfer, which is exemplified by the coupling of benzyl alcohol and aniline into N-benzylaniline with a turnover frequency (TOF) value of 7.0 molN-benzylaniline molmetal-1 h-1 ; this TOF outpaces that of reported stable non-noble-metal-based catalysts by a factor of 2.

Background: Klebsiella pneumoniae carbapenemase (KPC) has spread across the world. The present study focuses on explore sequence and evolution pathway of two potentially epidemic KPC-harbouring plasmids in Klebsiella pneumonia isolated from Southern China.Methods: Eighteen carbapenemases-producing Klebsiella pneumonia isolates were collected in a tertiary teaching hospital in 2014 in Southern China. The KPC production, antimicrobial susceptibility and MLST were tested for all isolates. Plasmids were purified for all isolates. Plasmids of six isolates were randomly selected to perform Single-molecule real-time sequencing, annotation and bioinformatics analysis. Conjugation and transformation experiment were also performed for the six selected plasmid samples. Furthermore, PCR screening based on the plasmid sequences information were performed for other twelve isolates, to identify the prevalence of the identified plasmids.Results: Two new KPC plasmids, pF5 and pF77, were identified and detected to be highly epidemic in the collected isolates with the rate of 77.8% (14/18), and 92.9% of the plasmid-harbouring isolates were identified in sequence type (ST) 11 group. pF5 belongs to the incompatibility group IncR and IncFIIk, and pF77 belongs to IncFIIk. The two plasmids were non-conjugative. By sequencing and comparing the plasmids sequences in detail, we found these plasmids carrying bla KPC-2 , bla CTX-M-65 , bla SHV-12 , catA2 and fosA3 antimicrobial genes. Additionally, the two plasmids both showed a close relationship with the other two reported KPC-harbouring plasmids pKP1034 and pCT-KPC, which have highly similar backbones and have been considered to evolve from some recombination events of other closely related plasmids pHN7A8, pKPC-LK30 and pKPHS2. We noticed that these previous reported plasmids and our plasmids all have been detected in the period of 2013-2014 in Southern China, share similar backbone and carried by the clonal ST11 K. pneumonia strains.Conclusions: The plasmids were identified and detected to be highly epidemic in the collected isolates. A potential evolutionary pathway from pHN7A8-, pKPC-LK30 and pKPHS2-derived plasmids in Klebsiella pneumoniae strains in China was hypothesised.

Ba(Co1/3(Nb1-xW5x/6)2/3)O3 (06+. The Ba(Co1/3(Nb1-xW5x/6)2/3)O3 solid solution is formed with the small substitution of W6+ (x≤0.01). With the increase of x, the impurity phase BaWO4 occurrs and the grains become less homogeneous. Combined with the analysis of X-Ray Diffraction, the cation ordering degree on B-site increases in the sample of x=0.01, which leads to the decrease of the dielectric loss. However, the second phase BaWO4 inhibits the formation of the ordered structure with the reduction of sinterability. Due to the formation of BaWO4, the values of εr and τf of all samples decrease subsequently. The optimized microwave dielectric properties of Ba(Co1/3(Nb1-xW5x/6)2/3)O3 ceramics were obtained in the samples of x=0.01: εr=33.8, Q×f =110761 GHz, τf = -17 ppm/°C.

The current investigation explores whether extended-spectrum β-lactamase (ESBL) genes exist in clinical non-ESBL-producing Klebsiella pneumoniae isolates.A total of 202 clinical isolates with non-ESBL-producing K. pneumoniae were collected from southern and middle of China. Thirteen β-lactamase genes (blaA total of 8.9% (18/202) isolates carried ESBL genes. All of them harbored only one ESBL gene, including 33.3% (6/18) blaClinical non-ESBL-producing K. pneumoniae isolates could carry ESBL genes with intact promoter, but without the correlated phenotype. Specific silencing mechanisms may play an important role in regulating ESBL gene expression. This kind of isolates has the potential to transfer their ESBL genes to other bacteria with effective promoters, resulting in ESBL phenotype.

To fully identify the formation and source characteristics of aerosol nitrate during winter which accompanied by frequent haze in Northeast China, the nitrate concentrations, δ15N–NO3- and δ18O–NO3- characteristics of PM2.5 samples from four sites of different types including the (a) urban area, (b) suburban area, (c) suburban-rural transition area and (d) rural area in Northeast China were analyzed in this work. δ15N isotope fractionation (eN) during the conversion of atmospheric NOX (δ15N-NOX) to nitrate (δ15N–NO3-) was discussed on the basis of the estimated contributions of the gas phase oxidation pathway of OH radical (·OH) (γOH) and the heterogeneous hydrolysis pathway of N2O5 (γN2O5) to nitrate formation. Besides, the contribution of biological soil, coal combustion, biomass burning and motor vehicles to NOX emissions had also been analyzed using Bayesian isotope mixing model. Results showed that different types of sites had inconsistent source contributions. Obviously, coal combustion plays an absolutely indispensable role in the production of NOX in all the sites, especially in rural areas (d), where coal combustion contributed up to 89.8%. In addition, biomass burning still has a great effect on NOX emissions in the Northeast, showing a contribution of 5.2%–35.8%. It is worth noting that in urban site (a) where the tropospheric O3 concentration (34±9 μg m−3) was significantly lower than the other regions ((b): 54 ± 16 μg m−3, (c): 101 ± 21 μg m−3, (d): 98 ± 17 μg m−3), the contribution of the ·OH pathway to nitrate was as high as 69.4%, which was very different from the other three sites. The different formation mechanisms of nitrate in urban and non-urban may be due to different O3. Haze not only affects the sources of nitrate, but also changes the contribution of nitrate formation. Except for rural site (d), the contribution of the heterogeneous reaction (N2O5 pathway) of the other three sites during the haze period was greater (a: 35.1%, b: 60.0%, c: 59.0%, d: 60.8%) than in the non-haze period (a: 22.5%, b: 44.7%, c: 41.9%, d: 64.2%).

To provide supplemental cooling to air cooled condenser (ACC) based thermo-electric power plants, radiative cooling is one of the options to ensure comparable efficiency as water cooled power plants. However, radiative cooling has relatively low energy intensity, about 100 W/m 2 cooling power on daily average. To work with power plants generally at few hundreds of megawatts, an intermediate system is needed to bridge this huge energy intensity mismatching at low energy cost. A low-pump-power demand pipe network is proposed to collect cold energy generated by the radiative cooling surfaces using water as the heat transfer fluid and the cold water is thus stored in intermediate storage devices. In this work, head loss and heat loss analysis models have been developed for the proposed constructal T-shaped network design, which provides convenience to integrate and scale up the radiative cooling modules to a large system to meet megawatt power plant’s supplemental cooling demand. A large radiative cooling system may consist of hundreds to thousand radiative cooled-cold (RadiCold) storage subsystems at a size of about 200-kW th each. Design of the 200-kW th RadiCold subsystem with constructal T-shaped network shows 11 kWh/day for pump electricity consumption and delivers cold energy of 4096 kW th /day.

A single-phase thermosiphon is developed for cold collection and storage of radiative cooling. Compared to the conventional nocturnal radiative cooling systems that use an electric pump to drive the heat transfer fluid, the proposed single-phase thermosiphon uses the buoyancy force to drive heat transfer fluid. This solution does not require electricity, therefore improving the net gain of the radiative cooling system. A single-phase thermosiphon was built, which consists of a flat panel, a cold collection tank, a water return tube, and a water distribution tank. Considering that outdoor radiative cooling flux is constantly changing (i.e. uncontrollable), an indoor testing facility was developed to provide a controllable cooling flux (comparable to a radiative cooling flux of 100 W/m2) for the evaluation of thermosiphon performance. The testing apparatus is a chilled aluminum flat plate that has a controlled air gap separation relative to the flat panel surface of the thermosiphon to emulate radiative cooling. With an average of 105 W/m2 cooling flux, the 18 liters of water in the thermosiphon was cooled to an average temperature of 12.5 °C from an initial temperature of 22.2 °C in 2 h, with a cold collection efficiency of 96.8%. The results obtained have demonstrated the feasibility of using a single-phase thermosiphon for cold collection and storage of radiative cooling. Additionally, the effects of the thermosiphon operation conditions, such as tilt angle of the flat panel, initial water temperature, and cooling energy flux, on the performance have been experimentally investigated. Modular design of the single-phase thermosiphon gives flexibility for its scalability. A radiative cooling system with multiple thermosiphon modules is expected to play an important role in cooling buildings and power plant condensers.

We developed superconducting nanowire single-photon detectors based on tungsten silicide, which show saturated internal detection efficiency up to a wavelength of 10 μm. These detectors are promising for applications in the mid-infrared requiring sub-nanosecond timing, ultra-high gain stability, low dark counts, and high efficiency, such as chemical sensing, LIDAR, dark matter searches, and exoplanet spectroscopy.

Designing functional and reusable electrode materials to replace homogeneous versions of scarifying additives or mediators in electrochemical organic synthesis is of great importance for both the fundamental academics and practical production of various useful compounds. Herein, we rediscover the function of nitrogen-doped carbon monoliths (NxC) as de novo anode materials to trigger a new reaction path for the synthesis of acetals from the direct coupling of alcohols without the assistance of any mediator, oxidant, acid, or organic ligand. The lowered valence bands of carbon monoliths induced by doping nitrogen are of key importance for polarizing and activating the pre-adsorbed O–H groups of benzyl alcohol molecules to boost the high Faradaic efficiency (71% at 1.8 V versus Ag/AgCl) and reusability of NxC anodes, meeting the requirements of green chemistry.

The lazy way to keep cool in the sun Passive radiative cooling requires a material that radiates heat away while allowing solar radiation to pass through. Zhai et al. solve this riddle by constructing a metamaterial composed of a polymer layer embedded with microspheres, backed with a thin layer of silver (see the Perspective by Zhang). The result is an easy-to-manufacture material near the theoretical limit for daytime radiative cooling. The translucent and flexible film can be made in large quantities for a variety of energy technology applications. Science , this issue p. 1062 ; see also p. 1023

Aims: This work investigated the relative strengths of different blaSHV promoter-associated sequences and their regulation function in blaSHV expression and β-lactam resistance. Methods: Recombinant plasmids with the promoter-associated sequences (P-W, P-S, P-IS, and P-WPD), tac promoter, and combined fragments of promoter and blaSHV were separately constructed and transformed into Escherichia coli DH5α. The relative strengths of the promoters indicated by the intensities of green fluorescent protein and the mRNA expression levels of blaSHV were compared. The minimum inhibitory concentration and extended spectrum β-lactamase phenotypes were evaluated. Results: The relative strengths were ranked as P-tac > P-WPD > P-IS > P-S > P-W. The mRNA expression and β-lactam resistance levels of the different promoter-associated sequence groups were generally consistent with the strength rank, but the extent of gfp and blaSHV mRNA levels varied significantly in each group. The β-lactam resistance levels were inconsistent with the strength rank in certain blaSHV groups. In relation to the different promoter-associated sequences, blaSHV-ESBLs displayed significantly different change modes of β-lactam resistance compared with blaSHV-non-ESBLs. Conclusion: The mRNA expression and β-lactam resistance of the blaSHV showed consistencies and inconsistencies with the strengths of the promoter-associated sequences. The mechanisms accounting for these discrepancies need further investigation.

Predicting tropospheric cloud formation and subsequent nutrient deposition relies on understanding the sources and processes affecting aerosol constituents of the atmosphere that are preserved in cloud water. However, this challenge is difficult to address quantitatively based on the sole use of bulk chemical properties. Nitrogenous aerosols, mainly ammonium (NH4+) and nitrate (NO3-), play a particularly important role in tropospheric cloud formation. While dry and wet (mainly rainfall) deposition of NH4+ and NO3- are regularly assessed, cloud water deposition is often underappreciated. Here we collected cloud water samples at the summit of Mt. Tai (1545 m above sea level) in eastern China during a long-lasting biomass burning (BB) event and simultaneously measured for the first time the isotopic compositions (mean ±1σ) of cloud water nitrogen species (δ15N-NH4+ = −6.53 ‰ ± 4.96 ‰, δ15N-NO3- = −2.35 ‰ ± 2.00 ‰, δ18O-NO3- = 57.80 ‰ ± 4.23 ‰), allowing insights into their sources and potential transformation mechanism within the clouds. Large contributions of BB to the cloud water NH4+ (32.9 % ± 4.6 %) and NO3- (28.2 % ± 2.7 %) inventories were confirmed through a Bayesian isotopic mixing model, coupled with our newly developed computational quantum chemistry module. Despite an overall reduction in total anthropogenic NOx emission due to effective emission control actions and stricter emission standards for vehicles, the observed cloud δ15N-NO3- values suggest that NOx emissions from transportation may have exceeded emissions from coal combustion. δ18O-NO3- values imply that the reaction of OH with NO2 is the dominant pathway of NO3- formation (57 % ± 11 %), yet the contribution of heterogeneous hydrolysis of dinitrogen pentoxide was almost as important (43 % ± 11 %). Although the limited sample set used here results in a relatively large uncertainty with regards to the origin of cloud-associated nitrogen deposition, the high concentrations of inorganic nitrogen imply that clouds represent an important source of nitrogen, especially for nitrogen-limited ecosystems in remote areas. Further simultaneous and long-term sampling of aerosol, rainfall, and cloud water is vital for understanding the anthropogenic influence on nitrogen deposition in the study region.

Production of ammonia is currently realized by the Haber–Bosch process, while electrochemical N2 fixation under ambient conditions is recognized as a promising green substitution in the near future. A lack of efficient electrocatalysts remains the primary hurdle for the initiation of potential electrocatalytic synthesis of ammonia. For cheaper metals, such as copper, limited progress has been made to date. In this work, we boost the N2 reduction reaction catalytic activity of Cu nanoparticles, which originally exhibited negligible N2 reduction reaction activity, via a local electron depletion effect. The electron-deficient Cu nanoparticles are brought in a Schottky rectifying contact with a polyimide support which retards the hydrogen evolution reaction process in basic electrolytes and facilitates the electrochemical N2 reduction reaction process under ambient aqueous conditions. This strategy of inducing electron deficiency provides new insight into the rational design of inexpensive N2 reduction reaction catalysts with high selectivity and activity., Electrocatalytic nitrogen reduction is promising for ammonia production, but electrocatalysts are limited by low efficiency and high cost. Here, the authors report electron-deficient copper nanoparticles, induced by rectifying contact with polyimide, for selective reduction of nitrogen to ammonia.

The traditional NH

A nitrogen-thermal approach via the reaction between transition metal species and N dopants affords us the ability to optimize the tradeoff between the number of exposed transition metal/carbon (exemplified by cobalt in this work) boundaries and the most pronounced interfacial rectifying contact to achieve the highly efficient and selective hydrogenation and dehydrogenation of N-heterocycle compounds in a reversible manner.

Ammonium salts, including ammonium nitrate, ammonium sulfate and ammonium hydrogen sulfate, are the main components of secondary inorganic aerosols and play an important role in the formation of haze events. The sources and transformation processes of atmospheric ammonium have received more and more attention. In this study, we modified the previous stable isotope analysis technique by improving the injection volume and adding a pH adjustment step, which gave a rapid and accurate measurement of ammonium nitrogen isotope ratio in atmospheric aerosol samples. Firstly, we added alkaline hypobromite to the extracted solution of the atmospheric aerosol filter samples (0.25 μg·mL硝酸铵、硫酸铵和硫酸氢铵等铵盐作为PM

We described an effective way to generate a Co

Biomass burning can significantly impact the chemical and optical properties of carbonaceous aerosols. Here, the impacts of biomass burning emissions on chemical and optical properties of carbonaceous aerosols were studied during wintertime in a megacity of Nanjing, East China. The high abundance of biomass burning tracers such as levoglucosan (lev), mannosan (man), galactosan (gal) and non-sea-salt potassium (nss-K+) was found during the studied period with the concentration ranges of 22.4–1476 ng m−3, 2.1–56.2 ng m−3, 1.4–32.2 ng m−3, and 0.2–3.8 μg m−3, respectively. Backward air mass origin analysis, potential emission sensitivity of element carbon (EC), and MODIS fire spot information indicated that the elevations of the carbonaceous aerosols were due to the transported biomass-burning aerosols from Southeast China. The characteristic mass ratio maps of lev/man and lev/nss-K+ suggested that the biomass fuels were mainly crop residuals. Furthermore, the strong correlation (p abs) for water soluble organic carbon (WSOC) revealed that biomass burning emissions played a significant role in the light-absorption properties of carbonaceous aerosols. The solar energy absorption due to water-soluble brown carbon (BrC) and EC was estimated by the calculation-based on measured light-absorbing parameters and the simulation-based on a radiative transfer model (RRTMG_SW). The solar energy absorption of water-soluble BrC in short wavelengths (300–400 nm) was 0.8 ± 0.4 (0.2–2.3) W m−2 from the calculation-based and 1.2 ± 0.5 (0.3–1.9) W m−2 from the RRTMG_SW model. The absorption capacity of water-soluble BrC accounted for about 20–30 % of the total absorption of EC aerosols. The solar energy absorption of WSOC due to biomass burning was estimated as 0.2 ± 0.1 (0.0–0.9) W m−2. Potential Source Contribution Function model simulations showed that the solar energy absorption induced by WSOC and EC aerosols was mostly due to the regional transported carbonaceous aerosols from the source regions such as southeast China. Our results illustrate the importance of the absorbing water-soluble brown carbon aerosols in trapping additional solar energy in the low-level atmosphere, heating the surface and inhibiting the energy from escaping the atmosphere. The regional transported biomass burning emissions may significantly impact the chemical and optical properties of carbonaceous aerosols in the polluted atmosphere.

The interpretation of tropospheric cloud formation rests on understanding the sources and processes affecting aerosol constituents of the atmosphere that are preserved in cloudwater. However, this challenge is difficult to be quantitatively addressed based on the sole use of bulk chemical properties. Nitrogenous aerosols, mainly ammonium (NH4+) and nitrate (NO3−), play an important role in tropospheric cloud formation. Here we collected cloudwater samples at the summit of Mt. Tai (1545 m above sea level) in Eastern China during a long-lasting biomass burning (BB) event, and measured for the first time the isotopic compositions (mean ± 1σ) of cloudwater nitrogen species (δ15N-NH4+ = −6.53 ± 4.96 ‰, δ15N-NO3− = −2.35 ± 2.00 ‰, δ18O-NO3− = 57.80 ± 4.23 ‰), allowing insights into their sources and potential transformation mechanism within the clouds. Large contributions of BB to the cloudwater NH4+ (32.9 ± 4.6 %) and NO3− (28.2 ± 2.7 %) inventories were confirmed through a Bayesian isotopic mixing model, coupled with our newly-developed computational quantum chemistry module. Despite an overall reduction in total anthropogenic NOx emission due to effective emission control actions and stricter emission standards for vehicles, the observed cloud δ15N-NO3− values suggest that NOx emissions from transportation may have exceeded emissions from coal combustion. δ18O-NO3− values imply that the reaction of OH with NO2 is the dominant pathway of NO3− formation (57 ± 11 %), yet the contribution of heterogeneous hydrolysis of dinitrogen pentoxide was almost as important (43 ± 11 %).