Emergence of the resistance-nodulation-division efflux pump tmexCD3-toprJ3 gene confers resistance to tigecycline in Pseudomonas juntendi and Proteus terrae isolated from a pig farm in China.

BACKGROUND: Tigecycline is regarded as a last-resort antimicrobial agent against multidrug resistance (MDR). However, resistance-nodulation-division efflux pump resistance genes, such as tmexCD3-toprJ3, that confer resistance to tigecycline have emerged. OBJECTIVES: This study aimed to characterise the tmexCD3-toprJ3 gene cluster in Pseudomonas juntendi and Proteus terrae isolated from a pig farm. METHODS: Samples were obtained from a Chinese piggery and included 92 pig faecal samples, 56 wastewater samples, 23 drinking water samples, 28 sow vagina samples and nine sow uterus swabs. The presence of tmexCD3-toprJ3 was detected using a polymerase chain reaction assay, and the antimicrobial susceptibility profile of the tmexCD3-toprJ3-positive isolates was determined using the broth dilution method. Genomic locations were identified using whole-genome sequencing and bioinformatics. RESULTS: We identified two tmexCD3-toprJ3-positive isolates, and both isolates were highly resistant to antibiotics such as tigecycline. In addition, we identified several mobile elements (ISPa7, ISCfr1, ISVsa3) and insertion sequences (TnAs2, TnAs3) in tmexCD3-toprJ3-positive isolates that could increase the potential for the spread of MDR. CONCLUSIONS: To the best of our knowledge, this study is the first to report the detection of tmexCD3-toprJ3 in P. juntendi and P. terrae isolated from a pig farm.

Prevalence and Characteristics of mcr-1-Producing Escherichia coli in Three Kinds of Poultry in Changsha, China.

Colistin is one of the last-line drugs against difficult to treat and multidrug-resistant Gram-negative bacteria. The emergence of mobile colistin resistance gene mcr-1 increased worldwide attention on colistin resistance. mcr-1 is the dominant gene that caused resistance to colistin in chicken-derived Escherichia coli (E. coli) in China; it has a broad resistance spectrum and causes multiple drug resistance problems. There are only few studies on mcr-positive E. coli (MCRPEC) from laying ducks and quails in China. Here, the molecular and epidemiological characteristics of MCRPEC from three kinds of poultry farms (laying duck, quail, and broiler) were investigated in Changsha, China. A total of 17 mcr-positive E. coli (MCRPEC) strains were screened in 690 samples from the three kinds of poultry farms. This is the first report on MCRPEC, to our best knowledge, derived from quail. All the MCRPEC strains were resistant to colistin, sulfamethoxazole-trimethoprim, florfenicol, tetracycline, and ciprofloxacin, and mildly resistant to tigecycline, gentamicin, piperacillin/tazobactam, cefotaxime, and ceftiofur. All the strains were sensitive to meropenem and amikacin. By bioinformatics analysis, 17 MCRPEC strains belonging to 11 MLST types were distributed in phylogroups A (58.8%), B1 (23.5%), and phylogroup D (17.6%). mcr-1 was located in IncI2 plasmid with typical plasmid conjugation transfer part, type IV secretory system, and tellurium-resistant protein, increasing transmission capacity to other bacteria. Monitoring of colistin-resistant bacteria in poultry farms should be strengthened.

Prevalence and antimicrobial susceptibility of CTX-M-type-producing Escherichia coli from a wildlife zoo in China.

BACKGROUND: Wildlife zoos provide the opportunity for children and adults to interact with animals, However, it's unknown that the risk of contact with animals, which carried zoonotic pathogens and antimicrobial resistant bacteria. OBJECTIVES: This study aimed to investigate the prevalence and antimicrobial susceptibility of extended-spectrum ß-lactamases Escherichia coli (ESBLs-EC) from a wildlife zoo in China. METHODS: A total of 93 wildlife faecal samples were collected from a wildlife zoo. Agar dilution method was used to determine the resistant phenotype. Whole genomes sequencing and bioinformatic analysis were employed to evaluate the molecular typing and genetic relationships of ESBLs-EC. RESULTS: A total of 23 CTX-M-positive ESBLs-EC were isolated from swan (n = 14), squirrel monkey (n = 5), black hat hanging monkey (n = 2), gibbon monkey (n = 1) and phoenicopteridae (n = 1) respectively. All ESBLs-EC strains were resistant to cefotaxime, tetracycline, ciprofloxacin and trimethoprim-sulfamethoxazole, but susceptible to colistin, tigecycline, meropenem and amikacin. By screening whole genome sequences, ESBLs-EC strains main carried blaCTX-M-55 (34.8%, 8/23) and blaCTX-M-14 (26.0%, 6/23), following by blaCTX-M-27 (21.7%, 5/23), blaCTX-M-15 (13.0%, 3/23) and blaCTX-M-121 (4.3%, 1/23). ESBLs-EC strains mainly belonged to phylogroup A (60.9%, 14/23), and ST48, ST746 and ST616 (3 strains respectively, 13.0%) were major ST types. Core genome-based single nucleotide polymorphism (SNP) analysis suggested that strains from the swan, over the phylogenetic tree, have a closer genetic relationship with strains from other animals (black hat hanging monkey, gibbon monkey, phoenicopteridae and squirrel monkey). CONCLUSIONS: CTX-M type ESBLs-EC can transmit between animals in wildlife zoos, which may be a risk of spread to animal keepers, veterinarians and visitors when contact with animals. Our study provides that the importance of hygiene measures to minimise the risk of transmission of ESBLs-EC to visitors in wildlife zoos.

Two Photon-Pumped Whispering-Gallery Mode Lasing and Dynamic Regulation.

Realizing the dynamic regulation of nonlinear optical signals has a great scientific significance for the development of new-type nonlinear optoelectronic devices and expands its application in the field of laser technology, spectroscopy, material structure analysis, etc. Here, two photon absorption-induced whispering-gallery mode lasing from a single ZnO microresonator with a relatively low lasing threshold (15 µW) and high quality factor (Q ≈ 3200) under ambient conditions is demonstrated. Furthermore, success is achieved in obtaining the dynamic regulation of two photon-pumped lasing mode in the UV gain region. The corresponding resonant wavelength can be tuned dynamically from 388.99 and 391.12 to 390.01 and 392.12 nm for TE33 and TE32 modes, respectively. This work provides a new strategy for building high-performance mode-adjustable frequency upconversion lasers.

Historical changes in the major and trace elements in the sedimentary records of Lake Qinghai, Qinghai-Tibet Plateau: implications for anthropogenic activities.

Sediment sequences in Lake Qinghai spanning the past 100 years were explored to assess the effects of changes in local land desertification, dust input and agriculture on sediment deposition in different parts of Lake Qinghai. Three short sediment cores (QH01, QH02, QH07) were collected from the main lake and one sediment core (Z04) from a sublake (Lake Gahai) of Lake Qinghai, China, during 2012 and 2013. The concentrations of Fe, Mn, Al, Rb, Ti, Ca, and Sr were analysed to determine the effects of historical and regional anthropogenic activities in the Lake Qinghai catchment from 1910 to 2010. The elemental concentrations in the sediment cores ranged from 1.85 to 2.79% for Fe, 397 to 608 µg/g for Mn, 3.04 to 5.64% for Al, 13.5 to 19.7 µg/g for Rb, 0.171 to 0.268% for Ti, 9.43 to 13.9% for Ca, 652 to 1020 µg/g for Sr, and 0.049 to 0.075% for P. Good correlations were found between the concentrations of Fe, Mn, Al, and Rb, and the Ti/Al ratios in the sediments suggest that these elements share a similar source. The enrichment factors (EFs) of Ti [EF(Ti)] and P [EF(P)] in each core were utilized to reflect variations in anthropogenic activities from 1950 to 2010. EF(Ti) ranged from 1 to 1.17 in QH01 and QH02, reflecting the variation of land desertification areas in the Buha River catchment from 1950 to 2010. The EF(Ti) showed positive linear correlations with the variation in cropland area in Gangcha County, suggesting that agricultural activity in the Quanji River and Shaliu River catchments was enhanced from 1950 to 2010. The sediment records showed similar biogeochemical changes in most lakes and bays in China, indicating that the intensity of changes in anthropogenic activities was caused by national policy enforcement from the 1950s to 2010. EF(Ti) can serve as a tracer for anthropogenic activities in Lake Qinghai, with the anthropogenic activities in different parts of the Lake Qinghai catchment represented in the homologous sediments from parts of Lake Qinghai over the past 100 years. The variation of EF(P) increased from 1 to 1.55 from deep layer to upper layer in all sediment cores, reflecting the increased fertilizer input and tourism activity from 1980 to 2010, a period during which the lake was evolved into a eutrophic lake.

Controllable Growth of Aligned Monocrystalline CsPbBr3 Microwire Arrays for Piezoelectric-Induced Dynamic Modulation of Single-Mode Lasing.

CsPbBr3 shows great potential in laser applications due to its superior optoelectronic characteristics. The growth of CsPbBr3 wire arrays with well-controlled sizes and locations is beneficial for cost-effective and largely scalable integration into on-chip devices. Besides, dynamic modulation of perovskite lasers is vital for practical applications. Here, monocrystalline CsPbBr3 microwire (MW) arrays with tunable widths, lengths, and locations are successfully synthesized. These MWs could serve as high-quality whispering-gallery-mode lasers with high quality factors (>1500), low thresholds (<3 µJ cm-2 ), and long stability (>2 h). An increase of the width results in an increase of the laser quality and the resonant mode number. The dynamic modulation of lasing modes is achieved by a piezoelectric polarization-induced refractive index change. Single-mode lasing can be obtained by applying strain to CsPbBr3 MWs with widths between 2.3 and 3.5 µm, and the mode positions can be modulated dynamically up to ≈9 nm by changing the applied strain. Piezoelectric-induced dynamic modulation of single-mode lasing is convenient and repeatable. This method opens new horizons in understanding and utilizing the piezoelectric properties of lead halide perovskites in lasing applications and shows potential in other applications, such as on-chip strain sensing.

Flexible Photodetector Arrays Based on Patterned CH3 NH3 PbI3- x Clx Perovskite Film for Real-Time Photosensing and Imaging.

The quest for novel deformable image sensors with outstanding optoelectronic properties and large-scale integration becomes a great impetus to exploit more advanced flexible photodetector (PD) arrays. Here, 10 × 10 flexible PD arrays with a resolution of 63.5 dpi are demonstrated based on as-prepared perovskite arrays for photosensing and imaging. Large-scale growth controllable CH3 NH3 PbI3- x Clx arrays are synthesized on a poly(ethylene terephthalate) substrate by using a two-step sequential deposition method with the developed Al2 O3 -assisted hydrophilic-hydrophobic surface treatment process. The flexible PD arrays with high detectivity (9.4 × 1011 Jones), large on/off current ratio (up to 1.2 × 103 ), and broad spectral response exhibit excellent electrical stability under large bending angle (θ = 150°) and superior folding endurance after hundreds of bending cycles. In addition, the device can execute the functions of capturing a real-time light trajectory and detecting a multipoint light distribution, indicating that it has widespread potential in photosensing and imaging for optical communication, digital display, and artificial electronic skin applications.

A Highly Symmetric Ionic Crystal Constructed by Polyoxoniobates and Cobalt Complexes for Preferential Water Uptake over Alcohols.

An ionic crystal assembled by PNb12O40(VO)6 and tris(1,2-diaminopropane)cobalt complexes was hydrothermally isolated and structurally characterized by routine methods. The compound exhibits three-dimensional channels with a pore size of 3.68 Å × 2.30 Å and composed of hydrophilic oxygen atoms of polyanions and hydrophobic -CH3 groups of 1,2-diaminopropane ligands. With increasing vapor pressure, the compound shows preferable adsorption toward water over alcohols, and a gate-opening behavior was deduced from the water adsorption isotherm.

Immobilization of Keggin polyoxovanadoniobate in crystalline solids to produce effective heterogeneous catalysts towards selective oxidation of benzyl-alkanes.

Two ionic organic-inorganic hybrid compounds, [CuII(C2N2H8)2]4[CuII(C2N2H8)2(H2O)2]2[PNb12O40VVVIVO2]·(OH)2·11H2O (1) and [CoIII(C2N2H8)3]2[CoIII(C2N2H8)2(H2O)2]0.5[H2.5PNb12O40 VVVIVO2]·20H2O (2), based on P-centered dicapped polyoxoniobates and organometallic cations were isolated and structurally characterized by routine techniques. The trivalent cobalt complex-containing compound exhibits a looser arrangement compared with its divalent copper complex-containing counterpart, with a space volume of 34.9% for the former and 17.0% for the latter. The two compounds were proved to be effective in facilitating the oxidation of benzyl-alkanes to ketone products in a heterogeneous manner, evidencing the feasiblity of the strategy of self-immobilization of catalytically active, readily soluble PNb12O40(VO)2 species in crystalline solids.

Regional environmental change and human activity over the past hundred years recorded in the sedimentary record of Lake Qinghai, China.

Environmental change and human activity can be recorded in sediment cores in aquatic systems such as lakes. Information from such records may be useful for environmental governance in the future. Six sediment cores were collected from Lake Qinghai, China and its sublakes during 2012 and 2013. Measurements of sediment grain-size fractions indicate that sedimentation in the north and southwest of Lake Qinghai is dominated by river input, whereas that in Lake Gahai and Lake Erhai is dominated by dunes. The sedimentation rates in Lake Qinghai were calculated to be 0.101-0.159 cm/y, similar to the rates in other lakes on the Qinghai-Tibetan Plateau. Using these data and sedimentation rates from the literature, we compiled the spatial distribution of sedimentation rates. Higher values were obtained in the three main areas of Lake Qinghai: two in river estuaries and one close to sand dunes. Lower values were measured in the center and south of the lake. Measurements of total organic carbon (TOC), total nitrogen (TN), phosphorus concentrations, and TOC/TN ratios in three cores (QH01, QH02, and Z04) revealed four horizons corresponding to times of increased human activity. These anthropogenic events were (1) the development of large areas of cropland in the Lake Qinghai watershed in 1960, (2) the beginning of nationwide fertilizer use and increases in cropland area in the lake watershed after 1970, (3) the implementation of the national program "Grain to Green," and (4) the rapid increase in the tourism industry from 2000. Profiles of Rb, Sr concentrations, the Rb/Sr ratio, and grain-size fraction in core Z04 indicate that the climate has become drier over the past 100 years. Therefore, we suggest that lake sediments such as those in Lake Qinghai are useful media for high-resolution studies of regional environmental change and human activity.

A Polyoxoniobate-Polyoxovanadate Double-Anion Catalyst for Simultaneous Oxidative and Hydrolytic Decontamination of Chemical Warfare Agent Simulants.

A novel double-anion complex, H13 [(CH3 )4 N]12 [PNb12 O40 (VV O)2 ⋅(VIV4 O12 )2 ]⋅22 H2 O (1), based on bicapped polyoxoniobate and tetranuclear polyoxovanadate was synthesized, characterized by routine techniques and used in the catalytic decontamination of chemical warfare agents. Under mild conditions, 1 catalyzes both hydrolysis of the nerve agent simulant, diethyl cyanophosphonate (DECP) and selective oxidation of the sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES). In the oxidative decontamination system 100 % CEES was transformed selectively to nontoxic 2-chloroethyl ethyl sulfoxide and vinyl ethyl sulfoxide using nearly stoichiometric 3 % aqueous H2 O2 with a turnover frequency (TOF) of 16 000 h-1 . Importantly, the catalytic activity is maintained even after ten recycles and CEES is completely decontaminated in 3 mins without formation of the highly toxic sulfone by-product. A three-step oxidative mechanism is proposed.

Sulfur-centred polyoxoniobate-based 3D organic-inorganic hybrid compound and its magnetic behavior.

The first sulfur-centered polyanion {SNb8V9.25O45.25} was isolated, which is covalently extended by cobalt complexes into a three-dimensional (3D) architecture. Moreover, the resulting 3D organic-inorganic hybrid compound orders as a weak ferromagnet at low temperature.

Controllable Assembly of Vanadium-Containing Polyoxoniobate-Based Three-Dimensional Organic-Inorganic Hybrid Compounds and Their Photocatalytic Properties.

The controllable synthesis of two vanadium-containing polyoxoniobate-based three-dimensional organic-inorganic hybrid compounds, [Co(pn)2]4[HPNb10V(IV)2O40(V(IV)O)4]·17H2O (1) and [Co(pn)2]5[PNb12O40(V(IV)O)6](OH)7·15H2O (2), where pn = 1,2-diaminopropane, is realized by changing the hydrothermal temperature or adding N-(aminoethyl)piperazine as an additive. Both compounds 1 and 2 are structurally characterized by single-crystal/powder X-ray diffraction and IR and X-ray photoelectron spectroscopy. Compound 1 features a new divanadium-substituted Keggin polyoxoniobate capped by four vanadyl groups, and the polyanion in 2 exhibits the highest coordination number (10-connected) in polyoxoniobate chemistry. Moreover, the photocatalytic activities of 1 and 2 for hydrogen evolution are preliminarily assessed.

Three new imidazole-functionalized hexanuclear oxidovanadium clusters with exceptional catalytic oxidation properties for alcohols.

Cluster cat: Three new imidazole-functionalized neutral hexanuclear vanadium clusters have been prepared, one of which shows exceptional catalytic activity in the selective aerobic oxidation of alcohols (see scheme). Furthermore, these new polyoxovanadium clusters can be readily recycled and reused with unchanged catalytic activity. A plausible catalytic cycle is also proposed.