Solar energy broadband capturing by metamaterial absorber based on titanium metal.

In recent years, the exploration of solar absorbers has grown in favor due to the scarcity of energy. Here, we propose an absorber with an array of a circular ring surrounding disk (RSD) for solar energy capture. The novel structure keeps above 93.5% absorption with an average absorption of 96.95% in wavelengths from 300 to 4000 nm. Meanwhile, the proposed absorber is advantageous in that the structure is generalizable to other metals and dielectric materials. Furthermore, the data results show that the absorber has polarization-independent properties as well as maintaining >90% absorption in the considered wavelength range up to an incidence angle of 52° and >95% absorption at large process tolerances. Finally, the excellent absorption under the AM1.5 solar spectrum demonstrates the RSD absorber's ability to capture solar energy. These results show the potential of the absorber for applications in electromagnetic invisibility cloaking, thermal emitters, and solar energy capture and conversion.

Evaluation of Organic Hydride/Acid Pairs as a Type of Thermodynamic-Potential-Regulated Multisite Proton-Coupled Electron Transfer Reagents.

Organic hydride/acid pairs have been reported as multisite proton-coupled electron transfer (MS-PCET) reagents in reductive MS-PCET reactions recently. Since the key step for an organic hydride/acid pair acting as an MS-PCET reagent is a chemical process of the organic hydride/acid pair releasing a formal hydrogen atom, the bond dissociation free energy of the organic hydride/acid pair releasing a formal hydrogen atom is a valuable thermodynamic parameter for objectively evaluating the thermodynamic potential for an organic hydride/acid pair to act as an MS-PCET reagent. Now, organic hydride/acid pairs of 216 organic hydrides have been demonstrated to be a potential type of thermodynamically potential-regulated MS-PCET reagent. Without a doubt, organic hydride/acid pairs reflect the change of N-substituted organic hydrides from simple hydride reductants to thermodynamically-regulated MS-PCET reagents, which could significantly expand the availability of novel MS-PCET reagents.

Effects of 6-month customized home-based exercise on motor development, bone strength, and parental stress in children with simple congenital heart disease: a single-blinded randomized clinical trial.

BACKGROUND: New "noncardiac" problems in children with congenital heart disease (CHD), such as developmental delay or long-term neurodevelopmental impairments, have attracted considerable attention in recent years. It is hypothesized that exercise might attenuate CHD-associated neurodevelopmental impairments; however, this has not been thoroughly investigated. The objective of this prospective, single-blinded, randomized controlled experiment was to evaluate the impact of customized home-based exercise for children with CHD. METHODS: Children aged 0-5 years with echocardiography-confirmed simple CHD subtypes who were scheduled to undergo cardiac catheterization were screened for enrolment. Among 420 screened CHD children, 192 were enrolled and randomly assigned at a 1:1 ratio to receive a 6-month intervention (30 min daily customized home-based exercise program with supervision for no less than 5 days per week, combined with home-based exercise education) or control treatment (home-based education). The primary outcome was motor development (gross motor quotient (GMQ), fine motor quotient (FMQ), and total motor quotient (TMQ)). The secondary outcomes were cardiac function and structure, bone quality, physical development, parental anxiety, caregiver burden, and quality of life. Children and their families were assessed before and 1, 3, and 6 months after catheterization; 183 (95.3%) children were included in the primary analysis. RESULTS: After 6-month treatment, the intervention group significantly increased their motor quotient, which was consistently higher than that of the control group (GMQ p < 0.0001, FMQ p = 0.02, TMQ p < 0.001). The physical developments in height, weight, and circumferences of the upper-arm, chest, and head were also significantly improved by exercise (all p < 0.017). No significant improvements in the bone strength or the cardiac structure and function were found among patients in the intervention group (all p > 0.017). For parents, higher quality of life level (total score p = 0.016) was observed in the intervention group; while effects of exercise on the anxiety (rude score p = 0.159, standard score p = 0.159) or the Zarit caregiver burden scale score (p = 0.404) were non-significant. No adverse events occurred during the study period. CONCLUSIONS: Customized home-based exercise improved motor development in children with CHD. While the long-term effects of parent training in home-based exercise are unknown, the study results suggest positive outcomes. TRIAL REGISTRATION: A home-based exercise program in congenital heart disease children with cardiac catheterization: a randomized controlled trial. ( http://www.chictr.org.cn/ , ChiCTR-IOR-16007762, January 14, 2016).

The relationship between triglyceride-glucose index and prospective key clinical outcomes in patients hospitalised for coronary artery disease.

BACKGROUND: The triglyceride-glucose (TyG) index is regarded as a dependable alternative for assessing insulin resistance (IR), given its simplicity, cost-effectiveness, and strong correlation with IR. The relationship between the TyG index and adverse outcomes in patients with coronary heart disease (CHD) is not well established. This study examines the association of the TyG index with long-term adverse outcomes in hospitalized CHD patients. METHODS: In this single-center prospective cohort study, 3321 patients hospitalized with CHD were included. Multivariate Cox regression models were employed to assess the associations between the TyG index and the incidence of all-cause mortality and major adverse cardiovascular events (MACEs). To examine potential nonlinear associations, restricted cubic splines and threshold analysis were utilized. RESULTS: During a follow-up period of 9.4 years, 759 patients (22.9%) succumbed to mortality, while 1291 (38.9%) experienced MACEs. Threshold analysis demonstrated a significant "U"-shaped nonlinear relationship with MACEs, with different hazard ratios observed below and above a TyG index of 8.62 (below: HR 0.71, 95% CI 0.50-0.99; above: HR 1.28, 95% CI 1.10-1.48). Notably, an increased risk of all-cause mortality was observed only when the TyG index exceeded 8.77 (HR 1.53, 95% CI 1.19-1.96). CONCLUSIONS: This study reveals a nonlinear association between the TyG index and both all-cause mortality and MACEs in hospitalized CHD patients with CHD. Assessing the TyG index, particularly focusing on individuals with extremely low or high TyG index values, may enhance risk stratification for adverse outcomes in this patient population.

Predicting potential distribution of the Rhinoncus sibiricus under climatic in China using MaxEnt.

In recent years, buckwheat (Fagopyrum spp.) is being increasingly damaged by the Siberian tortoise beetle (Rhinoncus sibiricus Faust). Adults and nymphs feed on leaf tissues and caulicles, thus damaging its stems and leaves. In this study, we investigated the habits, distribution, and environmental impact of R. sibiricus using MaxEnt, an ecological niche model. Geographic information about the infestation site from previous field surveys and climatic data from 2013 to 2018 were organized and optimized using R. The impact factors were calculated using MaxEnt software. The results indicate that population fluctuations in R. sibiricus are related to changes in temperature, humidity, and their spatial distribution. Under current climatic conditions, R. sibiricus is mainly distributed in northern China, with sporadic distribution in south-western China. The values for a survival probability threshold > 0.3 were: precipitation during the wettest month (bio13), 70.31-137.56 mm; mean temperature of the coldest quarter (bio11), -15.00-0.85°C; mean temperature of the warmest quarter (bio10), 11.88-23.16°C; precipitation during the coldest quarter (biol9), 0-24.39 mm. The main factors contributing > 70% to the models were precipitation during the wettest month and coldest quarter, and mean temperature during the warmest and coldest quarters. Under both future climate models, the center of the fitness zone moves northward. Our results will be useful in guiding administrative decisions and support farmers interested in establishing control and management strategies for R. sibiricus. This study could also serve as a reference for future research on other invasive pests.

CX3CR1 is a potential biomarker of immune microenvironment and prognosis in epithelial ovarian cancer.

Immunotherapy is less efficient for epithelial ovarian cancer and lacks ideal biomarkers to select the best beneficiaries for immunotherapy. CX3CR1 as chemokine receptor mainly expressed on immune cell membranes, and combined with its unique ligand CX3CL1, mediates tissue chemotaxis and adhesion of immune cells. However, the immune functional and prognostic value of CX3CR1 in epithelial ovarian cancer has not been clarified. A comprehensive retrospective analysis was performed by using the online database to identify the underlying immunological mechanisms and prognostic value of CX3CR1. The Human Protein Atlas, gene expression profiling interactive analysis, and TISIDB (an integrated repository portal for tumor-immune system interactions) database showed that CX3CR1 expressed higher in epithelial ovarian cancer than that in normal ovarian tissue. Four hundred twenty-two cases from Gene Expression Profiling Interactive Analysis and 1656 cases from Kaplan-Meier plotter database showed higher expression of CX3CR1 (above median) was associated with unfavorable overall survival. TIMER, UALCAN, and TISIDB database were applied to validate CX3CR1 negative impact on overall survival. In addition, correlation analysis showed that the expression level of CX3CR1 was positive association with infiltrating levels of B cells (R = 0.31, P = 3.10e-12), CD8+ T cells (R = 0.26, P = 7.93e-09), CD4+ T cells (R = 0.11, P = 1.41e-02), macrophages (R = 0.32, P = 4.29e-13), dendritic cells (R = 0.27, P = 2.98e-09), and neutrophil (R = 0.25, P = 3.25e-08) in epithelial ovarian cancer. Therefore, CX3CR1 involved in reshaping the immune microenvironment for epithelial ovarian cancer and maybe a potential immunotherapy target and prognostic marker for ovarian cancer.

Thermodynamic evaluations of the acceptorless dehydrogenation and hydrogenation of pre-aromatic and aromatic N-heterocycles in acetonitrile.

N-heterocycles are important chemical hydrogen-storage materials, and the acceptorless dehydrogenation and hydrogenation of N-heterocycles as organic hydrogen carriers have been widely studied, with the main focus on the catalyst synthesis and design, investigation of the redox mechanisms, and extension of substrate scope. In this work, the Gibbs free energies of the dehydrogenation of pre-aromatic N-heterocycles (YH2) and the hydrogenation of aromatic N-heterocycles (Y), i.e., ΔGH2R(YH2) and ΔGH2A(Y), were derived by constructing thermodynamic cycles using Hess' law. The thermodynamic abilities for the acceptorless dehydrogenation and hydrogenation of 78 pre-aromatic N-heterocycles (YH2) and related 78 aromatic N-heterocycles (Y) were well evaluated and discussed in acetonitrile. Moreover, the applications of the two thermodynamic parameters in identifying pre-aromatic N-heterocycles possessing reversible dehydrogenation and hydrogenation properties and the selection of the pre-aromatic N-heterocyclic hydrogen reductants in catalytic hydrogenation were considered and are discussed in detail. Undoubtedly, this work focuses on two new thermodynamic parameters of pre-aromatic and aromatic N-heterocycles, namely ΔGH2R(YH2) and ΔGH2A(Y), which are important supplements to our previous work to offer precise insights into the chemical hydrogen storage and hydrogenation reactions of pre-aromatic and aromatic N-heterocycles.

Essential Rule Derived from Thermodynamics and Kinetics Studies of Benzopyran Compounds.

Compounds with benzopyran as the core structure play an important role in the total synthesis of antioxidants, drugs, and natural products. Herein, the thermodynamic data of benzopyran compounds and their intermediates were measured and calculated by combining thermodynamics with kinetics. The mechanism of reactions between four benzopyran compounds and organic hydride acceptors was proven to be a one-step hydride transfer. The thermodynamic properties of these compounds and their corresponding intermediates were elucidated. The rationality and accuracy of the electrochemical measurement method were proved. Furthermore, the essential rule of unique structures being present between the C-H bond and para-substituent constants on the benzene ring, as shown in previous studies, was investigated. A simultaneous correlation between thermodynamics and kinetics was found for the hydride transfer reaction, in which the reaction site is connected with the substituent through the benzene ring, a double bond, or a N atom. The likely reason for the correlation between thermodynamic and kinetic is that the benzene ring, double bond, or N atom have the role of transferring the electronic effect. This finding can be applied to the calculation of the activation energy of hydride self-exchange reactions, the prediction of kinetic isotope effects, and explorations of selective reduction processes of hydride transfer in such organic hydride compounds.

Albumin-to-fibrinogen ratio is an independent prognostic parameter in de novo non-M3 acute myeloid leukemia.

Inflammation and nutrition related proteins participate in the development of acute myeloid leukemia (AML). It has been reported that the albumin-to-fibrinogen ratio (AFR) could serve as a prognostic indicator in patients with malignancy, but the precise relevance of AML is unclear. This study aimed to evaluate the effect of AFR on survival prognosis in patients with AML. We analyzed 227 patients newly diagnosed with non-M3 AML. AFR was calculated as albumin divided by fibrinogen. Based on the cutoff point from X-tile program, patients were divided into AFR-high (38.8%) and AFR-low (61.2%) groups. AFR-low group showed a poorer complete remission rate (P < 0.001) and median time to relapse (P = 0.026), while the mortality was higher (P = 0.009) than AFR-high ones. According to the log-rank test, AFR-low group had shorter OS (P < 0.001) and DFS (P = 0.034). Multivariate analysis identified AFR, ELN risk, bone marrow transplant, and hemoglobin as independent prognostic variables associated with OS. A visualized nomogram for predicting OS was performed. The C-index (0.75), calibration plots, and decision curve analyses of new model showed better discrimination, calibration, and net benefits than the ELN risk model. The time-dependent receiver operating characteristic (ROC) curve of 1-, 2-, and 3-year also functioned well (AUC, 0.81, 0.93 and 0.90, respectively). Our study provided a comprehensive view of AFR which could be an independent prognostic indicator in AML patients. The prognostic model utilized readily available information from ordinary clinical practice to improve predictive performance, identify risks, and assist in therapeutic decision-making.

Thermodynamic Evaluations of Amines as Hydrides or Two Hydrogen Ions Reductants and Imines as Protons or Two Hydrogen Ions Acceptors, as Well as Their Application in Hydrogenation Reactions.

Since the hydrogenation of imines (X) and the dehydrogenation of amines (XH2) generally involve the two hydrogen ions (H- + H+) transfer, the thermodynamic abilities of various amines releasing hydrides or two hydrogen ions as well as various imines accepting protons or two hydrogen ions are important and characteristic physical parameters. In this work, the pKa values of 84 protonated imines (XH+) in acetonitrile were predicted. Combining Gibbs free energy changes of amines releasing hydrides in acetonitrile from our previous work with the pKa(XH+) values, the Gibbs free energy changes of amines releasing two hydrogen ions and imines accepting two hydrogen ions were derived using Hess's law by constructing thermochemical cycles, and the thermodynamic evaluations of amines as hydrides or two hydrogen ions reductants and imines as protons or two hydrogen ions acceptors are well compared and discussed. Eventually, the practical application of thermodynamic data for amines and imines on hydrogenation feasibility, mechanism, and possible elementary steps was shown and discussed in this paper from the point of thermodynamics.

The Oriental spittlebug genus Paracercopis Schmidt (Hemiptera: Cercopoidea: Cercopidae) revisited, with description of one new species from Hubei, China.

The generic diagnostic characters of Paracercopis (Hemiptera: Cercopoidea: Cercopidae) are redefined and the autapomorphies are proposed to support the monophyly of the genus. Scanning electron micrographs of antennal sensilla and sensilla on rostral apex of P. seminigra (Melichar, 1902) are provided for the first time. A checklist together with new distribution records and key to the species of the genus are provided. Host plant associations of Paracercopis species are reported for the first time. Paracercopis unicolor Liang, Zhang & Xiao, sp. nov., representing the seventh and largest species of the genus is described from Hubei Province in south central China.

Characteristic Activity Parameters of Electron Donors and Electron Acceptors.

It is well-known that for an electron transfer reaction, the electron-donating ability of electron donors and the electron-accepting ability of electron acceptors can be quantitatively described by the oxidation potential of electron donors and the reduction potential of electron acceptors. However, for an electron transfer reaction, the electron-donating activity of electron donors and the electron-accepting activity of electron acceptors cannot be quantitatively described by a characteristic parameter of electron donors and a characteristic parameter of electron acceptors till now. In this paper, a characteristic activity parameter of electron donors and electron acceptors named as their thermo-kinetic parameter is proposed to quantify the electron-donating activity of electron donors and the electron-accepting activity of electron acceptors in electron transfer reactions. At the same time, the thermo-kinetic parameter values of 70 well-known electron donors and the corresponding 70 conjugated electron acceptors in acetonitrile at 298 K are determined. The activation free energies of 4900 typical electron transfer reactions in acetonitrile at 298 K are estimated according to the thermo-kinetic parameter values of 70 electron donors and 70 conjugated electron acceptors, and the estimated results have received good verification of the corresponding independent experimental measurements. The physical meaning of the thermo-kinetic parameter is examined. The relationship of the thermo-kinetic parameter with the corresponding redox potential as well as the relationship of the activation free energy with the corresponding thermodynamic driving force of electron transfer reactions is examined. The results show that the observed relationships between the thermo-kinetic parameters and the redox potentials as well as the observed relationships between the activation free energy and the thermodynamic driving force depend on the choice of electron donors and electron acceptors as well as the electron transfer reactions. The greatest contribution of this paper is to realize the symmetry and unification of kinetic equations and the corresponding thermodynamic equations of electron transfer reactions.

Square-package arrays for efficient trapping of terahertz waves.

In this paper, a broadband metamaterial absorber consisting of the doped silicon substrate and the square array of doped silicon covered by a SU-8 layer is presented. The target structure achieves an average absorption of 94.42% in the studied frequency range (0.5-8 THz). In particular, the structure exceeds 90% absorption in the frequency range of 1.44-8 THz, which is a significant increase in bandwidth relative to reported devices of the same type. Next, the near-perfect absorption of the target structure is verified by the impedance matching principle. Furthermore, through the analysis of the electric field distribution inside the structure, the physical mechanism of its broadband absorption is investigated and explained. Finally, the impact of fluctuations in the incident angle, polarization angle, and structural parameters on the absorption efficiency is examined at length. The analysis shows that the structure has characteristics, such as polarization insensitivity, wide-angle absorption, and good process tolerance. The proposed structure is advantageous for applications in THz shielding, cloaking, sensing, and energy harvesting.

Dissecting peri-implantation development using cultured human embryos and embryo-like assembloids.

Studies of cultured embryos have provided insights into human peri-implantation development. However, detailed knowledge of peri-implantation lineage development as well as underlying mechanisms remains obscure. Using 3D-cultured human embryos, herein we report a complete cell atlas of the early post-implantation lineages and decipher cellular composition and gene signatures of the epiblast and hypoblast derivatives. In addition, we develop an embryo-like assembloid (E-assembloid) by assembling naive hESCs and extraembryonic cells. Using human embryos and E-assembloids, we reveal that WNT, BMP and Nodal signaling pathways synergistically, but functionally differently, orchestrate human peri-implantation lineage development. Specially, we dissect mechanisms underlying extraembryonic mesoderm and extraembryonic endoderm specifications. Finally, an improved E-assembloid is developed to recapitulate the epiblast and hypoblast development and tissue architectures in the pre-gastrulation human embryo. Our findings provide insights into human peri-implantation development, and the E-assembloid offers a useful model to disentangle cellular behaviors and signaling interactions that drive human embryogenesis.

A Mechanism Study of Redox Reactions of the Ruthenium-oxo-polypyridyl Complex.

Over the years, RuIV(bpy)2(py)(O)2+([RuIVO]2+) has garnered considerable interest owing to its extensive use as a polypyridine mono-oxygen complex. However, as the active-site Ru=O bond changes during the oxidation process, [RuIVO]2+ can be used to simulate the reactions of various high-priced metallic oxides. In order to elucidate the hydrogen element transfer process between the Ruthenium-oxo-polypyridyl complex and organic hydride donor, the current study reports on the synthesis of [RuIVO]2+, a polypyridine mono-oxygen complex, in addition to 1H and 3H (organic hydride compounds) and 1H derivative: 2. Through 1H-NMR analysis and thermodynamics- and kinetics-based assessments, we collected data on [RuIVO]2+ and two organic hydride donors and their corresponding intermediates and established a thermodynamic platform. It was confirmed that a one-step hydride transfer reaction between [RuIVO]2+ and these organic hydride donors occurs, and here, the advantages and nature of the new mechanism approach are revealed. Accordingly, these findings can considerably contribute to the better application of the compound in theoretical research and organic synthesis.

Quantitative evaluation of H-donating abilities of C(sp3)-H bonds of nitrogen-containing heterocycles in hydrogen atom transfer reaction.

Nitrogen-containing heterocycles are an important class of antioxidants, and their reactivity and selectivity in hydrogen atom reactions have attracted significant interest from chemists. In this work, the kinetics of hydrogen atom transfer reactions from C(sp3)-H bonds of 28 nitrogen-containing heterocycles, oxygen-containing heterocycles, alicyclic amines and cycloalkanes, which were denoted as XH, to the CumO˙ radical, were investigated. The characteristic physical parameter of the substrate, i.e., the thermo-kinetic parameter ΔG≠o(XH), was determined using the kinetic equation [ΔG≠XH/Y = ΔG≠o(XH) + ΔG≠o(Y)] to quantitatively evaluate the H-donating ability of XH. The effects of the substrate structure, substituent attached to the nitrogen atom, and ring size on the H-donating ability were discussed carefully. By comparing the H-donating abilities of cycloalkanes, alicyclic amines and nitrogen/oxygen-containing heterocycles, the influence of the introduction of N, O, or carbonyl groups in the carbon ring on the H-donating ability of C(sp3)-H bond was determined. The electronic, steric and stereo-electronic effects of the groups were also discussed. Herein, we not only quantitatively determined the H-donating ability of the substrate, but also provided ideas for the synthesis of new antioxidants.

Impact of Accessory Corpus Luteum Induced by Gonadotropin-Releasing Hormone or Human Chorionic Gonadotropin on Pregnancy Rates of Dairy Cattle following Embryo Transfer: A META-Analysis.

The circulation of progesterone (P4) concentrations of recipients has positive correlations with embryo survival and pregnancy success of embryo transfer (ET) in dairy cows. One strategy to improve P4 concentration is the administration of gonadotropin-releasing hormone (GnRH) or human chorionic gonadotropin (hCG), thereby inducing the formation of accessory corpus luteum (CL). This study aimed at determining the efficacy of GnRH or hCG treatment regarding embryo transfer (ET) and providing a better clinical veterinary practice guidance. A meta-analysis was conducted on the data from 2048 treated recipient cows and 1546 untreated cows. By inducing the formation of accessory CL with GnRH (100 µg), GnRH analogue Buserelin (8-10 µg), or hCG (≥1500 IU) 5-11 days after synchronized ovulation, hCG alone achieved an improvement (RR = 1.39, p < 0.05), while GnRH and GnRH analogue did not result in significant changes (RR = 1.04, p = 0.26). Treatment with GnRH or hCG 5-7 days after synchronized ovulation was associated with increased chances of pregnancy compared with later treatment (11-14 days). Owing to the treatment, the pregnancy rate of cows with very poor fertility (<40%) was improved, while that of cows with good fertility (≥40%) was not affected. Treatment with GnRH or hCG greatly improved pregnancy rates of parous lactating cows (RR = 1.32, p < 0.05) compared with heifers (RR = 1.02, p > 0.05). Additionally, as indicated by pregnancy loss analysis, the treatment had no benefit on late embryo/early fetus survival at days 28-81. In conclusion, the induction of accessory CL with GnRH or hCG may benefit fertility and have important implications for the management of reproductive performance in the dairy industry.

Circ-USP9X interacts with EIF4A3 to promote endothelial cell pyroptosis by regulating GSDMD stability in atherosclerosis.

Endothelial pyroptosis is a pathological mechanism of atherosclerosis (AS). Circular RNAs (circRNAs) are vital in AS progression by regulating endothelial cell functions. The study aimed to explore whether circ-USP9× regulated pyroptosis of endothelial cell to involve in AS development and the molecular mechanism. Pyroptosis was determined using lactate dehydrogenase (LDH) assay, enzyme linked immunosorbent assay (ELISA), flow cytometry, propidium iodide (PI) staining assay, and western blot. The mechanism of circ-USP9× was determined using RNA pull-down and RNA binding protein immunoprecipitation (RIP) assays. Results showed that circ-USP9× was upregulated in AS and oxidized low-density lipoprotein (ox-LDL)-treated human umbilical vein endothelial cells (HUVECs). Knockdown of circ-USP9× suppressed ox-LDL induced pyroptosis of HUVECs. Mechanically, circ-USP9× could bind to EIF4A3 in the cytoplasm. Moreover, EIF4A3 was bound to GSDMD and further affects GSDMD stability. Overexpression of EIF4A3 rescued cell pyroptosis induced by circ-USP9× depletion. In short, circ-USP9× interacted with EIF4A3 to enhance GSDMD stability, thus further promoting ox-LDL-induced pyroptosis of HUVECs. These findings suggested that circ-USP9× participates in AS progression and may be a potential therapeutic target for AS.

Greater Invasion and Persistence of mcr-1-Bearing Plasmids in Escherichia coli than in Klebsiella pneumoniae.

The emergence of the plasmid-borne polymyxin resistance gene mcr-1 threatens the clinical utility of last-line polymyxins. Although mcr-1 has disseminated to various Enterobacterales species, the prevalence of mcr-1 is the highest among Escherichia coli isolates while remaining low in Klebsiella pneumoniae. The reason for such a difference in prevalence has not been investigated. In this study, we examined and compared the biological characteristics of various mcr-1 plasmids in these two bacterial species. Although mcr-1-bearing plasmids were stably maintained in both E. coli and K. pneumoniae, the former presented itself to be superior by demonstrating a fitness advantage while carrying the plasmid. The inter- and intraspecies transferability efficiencies were evaluated for common mcr-1-harboring plasmids (IncX4, IncI2, IncHI2, IncP, and IncF types) with native E. coli and K. pneumoniae strains as donors. Here, we found that the conjugation frequencies of mcr-1 plasmids were significantly higher in E. coli than in K. pneumoniae, regardless of the donor species and Inc types of the mcr-1 plasmids. Plasmid invasion experiments revealed that mcr-1 plasmids displayed greater invasiveness and stability in E. coli than in K. pneumoniae. Moreover, K. pneumoniae carrying mcr-1 plasmids showed a competitive disadvantage when cocultured with E. coli. These findings indicate that mcr-1 plasmids could spread more easily among E. coli than among K. pneumoniae isolates and that mcr-1 plasmid-carrying E. coli has a competitive advantage over K. pneumoniae, leading to E. coli being the main mcr-1 reservoir. IMPORTANCE As infections caused by multidrug-resistant "superbugs" are increasing globally, polymyxins are often the only viable therapeutic option. Alarmingly, the wide spread of the plasmid-mediated polymyxin resistance gene mcr-1 is restricting the clinical utility of this last-line treatment option. With this, there is an urgent need to investigate the factors contributing to the spread and persistence of mcr-1-bearing plasmids in the bacterial community. Our research highlights that the higher prevalence of mcr-1 in E. coli than in K. pneumoniae is attributed to the greater transferability and persistence of mcr-1-bearing plasmid in the former species. By gaining these important insights into the persistence of mcr-1 in different bacterial species, we will be able to formulate effective strategies to curb the spread of mcr-1 and prolong the clinical life span of polymyxins.

Thermodynamics Evaluation of Selective Hydride Reduction for α,ß-Unsaturated Carbonyl Compounds.

The selective reduction of α,ß-unsaturated carbonyl compounds is one of the core reactions and also a difficult task for organic synthesis. We have been attempting to study the thermodynamic data of these compounds to create a theoretical basis for organic synthesis and computational chemistry. By electrochemical measurement method and titration calorimetry, in acetonitrile at 298 K, the hydride affinity of two types of unsaturated bonds in α,ß-unsaturated carbonyl compounds, their single-electron reduction potential, and the single-electron reduction potential of the corresponding radical intermediate are determined. Their hydrogen atom affinity, along with the hydrogen atom affinity and proton affinity of the corresponding radical anion, is also derived separately based on thermodynamic cycles. The above data are used to establish the corresponding "Molecule ID Card" (Molecule identity card) and analyze the reduction mechanism of unsaturated carbonyl compounds. Primarily, the mixture of any carbonyl hydride ions and Ac-tempo+ will stimulate hydride transfer process and create corresponding α,ß-unsaturated carbonyl compounds and Ac-tempoH from a thermodynamic point of view.