Superconductivity and Fermi Surface Anisotropy in Transition Metal Dichalcogenide NbTe_2

Transition metal dichalcogenides, featuring layered structures, have aroused enormous interest as a platform for novel physical phenomena and a wide range of potential applications. Among them, special interest has been placed upon WTe_2 and MoTe_2, which exhibit non-trivial topology both in single layer and bulk as well as pressure induced or enhanced superconductivity. We study another distorted IT material NbTe_2 through systematic electrical transport measurements. Intrinsic superconductivity with onset transition temperature(T_c^(onset)) up to 0.72 K is detected where the upper critical field(H_c) shows unconventional quasi-linear behavior,indicating spin-orbit coupling induced p-wave paring. Furthermore, a general model is proposed to fit the angledependent magnetoresistance, which reveals the Fermi surface anisotropy of NbTe_2. Finally, non-saturating linear magnetoresistance up to 50 T is observed and attributed to the quantum limit transport.

Generation of Hepatitis B virus PreS2-S antigen in Hansenula polymorpha

Despite the long availability of a traditional prophylactic vaccine containing the HBV surface antigen(HBsA g) and aluminum adjuvant, nearly 10% of the population remains unable to generate an effective immune response. Previous studies have indicated that hepatitis B virus(HBV) PreS 2-S is abundant in T/B cell epitopes, which induces a stronger immune response than HBsA g, particularly in terms of cytotoxic T lymphocyte(CTL) reaction. In the current study, the HBV PreS 2-S gene encoding an extra26 amino acids(PreS 2 C-terminus) located at the N-terminus of HBsA g was cloned into the pV CH1300 expression vector. Pre S2-S expressed in the methylotrophic yeast, Hansenula polymorpha, was produced at a yield of up to 250 mg/L. Subsequent purification steps involved hydrophobic adsorption to colloidal silica, ion-exchange chromatography and density ultracentrifugation. The final product was obtained with a total yield of ~15% and purity of ~99%. In keeping with previous studies, ~22 nm viruslike particles were detected using electron microscopy. The generated PreS 2-S antigen will be further studied for efficacy and safty in animals.

基于多源资料的高原低涡源地研究

高原低涡是活跃于青藏高原近地面层的中尺度天气系统,是高原最重要的降水天气系统,少部分的低涡移出高原后在下游地区常带来灾害性的强降水天气。“青藏高原低涡切变线年鉴”(简称年鉴)是高原低涡研究的主要参考资料之一,但受到高原西部地区探空观测站点分布不足的影响,年鉴难以监测发源于高原西部的低涡。为了进一步提高对高原低涡源地的科学认识,本研究首先分析了影响高原低涡发生发展的环流在高原东西部地区的差异,结果表明高原西部地区的环流背景更有利于高原低涡形成。再利用2005~2019年暖季(5~9月)风云-2地球静止卫星观测的云迹风和黑体亮温资料对年鉴低涡进行重分析,表明年鉴中大部分的高原低涡可以溯源至高原西部地区。最后分析了在高原西部的3个新探空站(狮泉河、改则和申扎)建立前后年鉴中高原低涡源地的差异,发现增加的探空资料使位于高原西部的低涡源地大幅度增加。综合多源资料的结果,我们认为大多数高原低涡起源于高原西部,年鉴的结论可能源于高原西部的探空站不足的影响。本研究确认了再分析资料在高原低涡研究中的可用性和有效性,强调了卫星观测资料在高原天气系统研究中的重要性和进一步增强高原地区气象观测的迫切性。

AUTOSIM:Automated Urban Traffic Operation Simulation via Meta-Learning

Online traffic simulation that feeds from online information to simulate vehicle movement in real-time has recently seen substantial advancement in the development of intelligent transportation systems and urban traffic management.It has been a challenging problem due to three aspects:1)The diversity of traffic patterns due to heterogeneous layouts of urban intersections;2)The nature of complex spatiotemporal correlations;3)The requirement of dynamically adjusting the parameters of traffic models in a real-time system.To cater to these challenges,this paper proposes an online traffic simulation framework called automated urban traffic operation simulation via meta-learning(AUTOSIM).In particular,simulation models with various intersection layouts are automatically generated using an open-source simulation tool based on static traffic geometry attributes.Through a meta-learning technique,AUTOSIM enables an automated learning process for dynamic model settings of traffic scenarios featured with different spatiotemporal correlations.Besides,AUTOSIM is capable of adapting traffic model parameters according to dynamic traffic information in real-time by using a meta-learner.Through computational experiments,we demonstrate the effectiveness of the meta-learningbased framework that is capable of providing reliable supports to real-time traffic simulation and dynamic traffic operations.

Knockout of a rice K5.2 gene increases Ca accumulation in the grain

Rice is a staple food for half of the world’s population,but it is a poor dietary source of calcium(Ca)due to the low concentration.It is an important issue to boost Ca concentration in this grain to improve Ca deficiency risk,but the mechanisms underlying Ca accumulation are poorly understood.Here,we obtained a rice(Oryza sativa)mutant with high shoot Ca accumulation.The mutant exhibited 26%-53% higher Ca in shoots than did wild-type rice(WT)at different Ca supplies.Ca concentration in the xylem sap was 36% higher in the mutant than in the WT.There was no difference in agronomic traits between the WT and mutant,but the mutant showed 25% higher Ca in the polished grain compared with the WT.Map-based cloning combined with a complementation test revealed that the mutant phenotype was caused by an 18-bp deletion of a gene,OsK5.2,belonging to the Shaker-like K+channel family.OsK5.2 was highly expressed in the mature region of the roots and its expression in the roots was not affected by Ca levels,but upregulated by low K.Immunostaining showed that OsK5.2 was mainly expressed in the pericycle of the roots.Taken together,our results revealed a novel role for OsK5.2 in Ca translocation in rice,and will be a good target for Ca biofortification in rice.

Pd单原子/团簇高效催化铃木偶联反应

铃木偶联反应是合成聚烯烃、苯乙烯和联苯衍生物等功能性有机化合物的有力工具,广泛应用于精细化工、制药和生化工业领域.钯(Pd)基催化剂是目前性能最好的铃木偶联反应催化剂,但钯的低丰度和高成本限制了其大规模应用.因此,提高Pd原子的利用效率,降低Pd用量至关重要.减小金属纳米粒子的尺寸,使其成为小团簇甚至孤立的金属原子是实现金属原子高利用率的有效方法之一.此外,与纳米晶体相比,高度分散的Pd原子和具有低配位和不饱和构型的亚纳米团簇可能会导致催化活性位点数量增加,进而提升Pd基催化剂的性能.然而,高表面自由能使得合成高度分散的Pd单原子和亚纳米团簇变得困难,因此,如何制备具有优异铃木偶联反应催化性能的Pd单原子/团簇催化剂是一个极具挑战性的课题.本文开发了一种溶液快速退火(SRA)工艺来稳定氮掺杂介孔碳负载的Pd单原子/团簇(Pd/NMC),制得的催化剂表现出较好的催化铃木偶联反应性能.透射电子显微镜结果表明,所制Pd/NMC催化剂中Pd以单原子和小金属团簇(粒径为0.3-1.1 nm)的形式高度分散在氮掺杂介孔碳载体的表面;X射线衍射结果表明,该催化剂没有与Pd相关的衍射峰,进一步证明了Pd以单原子和小金属团簇,而非纳米晶的形式存在.这得益于SRA工艺创造的不平衡热条件,抑制了Pd原子的团聚,提高了Pd原子在载体表面的分散性.与商业Pd/C催化剂相比,Pd/NMC催化剂对氯苯的铃木偶联反应表现出更好的催化性能(100%的选择性和95%的产率)和稳定性(循环使用10次后活性几乎没有衰减),此外对其他衍生物底物同样表现出较好的催化性能.第一性原理计算表明,在Pd(111)上联苯解吸的吉布斯自由能为3.24 eV,显著高于Pd_(1)/NMC(0.72 eV)和Pd_(13)/NMC(1.31 eV),在理论上同样证明了与Pd纳米颗粒相比,Pd单原子/团簇催化剂更有利于反应物的转化.此外,本文新开发的前驱体SRA工艺可被用作稳定金属团簇(例如Pd、Pt、Ru)的通用方法,为构建高效、高度分散的金属原子和亚纳米团簇催化剂提供了新的可能性.

内镜下结直肠息肉切除术后复发的危险因素分析

目的探讨内镜下结直肠息肉切除术后复发的危险因素,以提出最佳的防治措施。方法回顾性分析2016年1月-2017年8月该院行内镜下结直肠息肉切除术163例患者的临床资料,术后随访1年,根据是否复发分为复发组与未复发组。比较两组患者临床资料引起术后复发的差异,包括:性别、年龄、肠息肉数目、肠息肉直径、肠息肉生长位置及组织病理类型等,并对筛选出的差异有统计学意义的危险因素进行多因素回归分析。结果男性、年龄≥60岁、肠息肉≥3个、肠息肉直径≥2 cm和腺瘤性肠息肉是影响术后复发的独立危险因素(P<0.05)。结论操作时应充分考虑引起内镜下结直肠息肉切除术后复发的危险因素,术后针对危险因素的分级及患者实际状况制定个性化的随访方案,有利于降低复发的风险。

Subsidy Policy System for Agricultural Natural Disasters in China

From theories and cases,this paper analyzed current situation of subsidy policy system for agricultural natural disasters in China.Improvement and perfection of subsidy policies for agricultural natural disasters need clear classification and additional special subsidy plan.It is recommended to improve and perfect subsidy policy system for agricultural natural disasters through attaching importance to scientific studies on reduction and prevention of agricultural disasters and gradually supplementing agricultural disaster reduction and prevention system.

Missed diagnosis of femoral deep artery rupture after femoral shaft fracture: A case report

BACKGROUND Vascular injury is a rare complication of femoral shaft fractures,and rupture of the deep femoral artery is more difficult to diagnose because of its anatomical location and symptoms.Despite its low incidence,deep femoral artery rupture can lead to life-threatening outcomes,such as compartment syndrome,making early identification and diagnosis critical.CASE SUMMARY A 45-year-old male patient was admitted to our hospital due to right lower limb trauma in a car accident,with complaints of severe pain and swelling on his right thigh.X-ray demonstrated a right femoral shaft fracture.During preparation for emergency surgery,his blood pressure and blood oxygen saturation dropped,and sensorimotor function was lost.Computed tomography angiography was performed immediately to confirm the diagnosis of rupture of the deep femoral artery and compartment syndrome,so fasciotomy and vacuum-assisted closure were performed.Rhabdomyolysis took place after the operation and the patient was treated with appropriate electrolyte correction and diuretic therapy.Twenty days after the fasciotomy,treatment with the Hoffman Type II External Fixation System was planned,but it was unable to be immobilized internally based on a new esophageal cancer diagnosis.We kept the external fixation for 1 year,and 3 years of follow-up showed improvement of the patient’s overall conditions and muscle strength.CONCLUSION For patients with thigh swelling,pain,anemia,and unstable vital signs,anterior femoral artery injury should be highly suspected.Once diagnosed,surgical treatment should be performed immediately and complications of artery rupture must be suspected and addressed in time.

Preface tovirtual special issue of biocatalysis

Catalysis plays an important role in human civilization and economic development.Every breakthrough related to the field of catalysis has great impact on our everyday lives.To achieve harmonious development between human and nature through developing chemical processes with environmental friendliness and atom economy,the improvement and innovation of catalytic systems have drawn great attention.Biocatalysis is the engine of life from the very beginning,which is the example that we always learn from,mimic,and aim to surpass in scientific research and industrial development.The goal of the development of biocatalysis technology is tomake our industrial manufacturing go undermild conditions as nature does.However,the current situation of biocatalysis application is still far from the ultimate aim,providing countless opportunities for further development.

Asymmetrical Fault Current Calculation Method and Influencing Factors Analysis of Droop-Controlled Inverters

Since the fault dynamic of droop-controlled inverter is different from synchronous generators (SGs), protection devices may become invalid, and the fault overcurrent may damage power electronic devices and threaten the safety of the microgrid. Therefore, it is imperative to conduct a comprehensive fault analysis of the inverter to guide the design of protection schemes. However, due to the complexity of droop control strategy, existing literatures have simplified asymmetric fault analysis of droop-controlled inverters to varying degrees. Therefore, accurate fault analysis of a droop-controlled inverter is needed. In this paper, by analyzing the control system, an accurate fault model is established. Based on this, a calculation method for instantaneous asymmetrical fault current is proposed. In addition, the current components and current characteristics are analyzed. It was determined that fault currents are affected by control loops, fault types, fault distance and nonlinear limiters. In particular, the influences of limiters on the fault model, fault current calculation and fault current characteristics were analyzed. Through detailed analysis, it was found that dynamics of the control loop cannot be ignored, the fault type and fault distance determine fault current level, and part of the limiters will totally change the fault current trend. Finally, calculation and experimental results verify the correctness of the proposed method.

具有涡流热效应的液态金属微球用于磁热增强的癌症栓塞-免疫联合治疗

肝细胞癌患者由于肝癌的高转移性和高复发率表现出预后差的特征.本文提出了一种通过磁热疗法(MHT)增强癌症免疫治疗联合经导管动脉栓塞(TAE)治疗肝癌肿瘤的有效策略.通过微流控技术制备的尺寸均匀液态金属微球(LM MSs),由于在交变磁场下的涡流热效应表现出显著的磁感应加热能力,可同时作为MHT和TAE两种癌症治疗策略的有效药物.一方面,LM MSs优异的涡流磁热效应表现出高效的MHT治疗疗效.另一方面,LM MSs引发的MHT可以显著增强免疫系统激活,促进免疫细胞的浸润;与免疫检查点阻断(ICB)治疗联合后可以进一步刺激强大的免疫应答,从而抑制远端肿瘤的生长.此外,LM MSs-碘油栓塞剂在兔子原位肝癌模型中表现出优异的栓塞-磁热联合治疗效果.总之,该工作不仅证明了LM MSs可以作为有效的MHT试剂实现MHT-免疫联合治疗,而且还展示了TAE与MHT联合治疗在原位大型肝肿瘤治疗中的重要应用前景.

Quantum Griffiths singularity in two-dimensional superconducting 4Ha-TaSe_(2) nanodevices

The layered transition metal dichalcogenides(TMDs)have raised considerable interest in the past decades for both fundamental physics and low-dimensional nanodevice applications.Recently,intriguing phenomena of Ising superconductivity and quantum metallic state have been reported in two-dimensional(2D)4Ha-TaSe2 nanodevices.Here,we report the magnetic field induced superconductor–metal transition(SMT)in mechanical exfoliated 4Ha-TaSe2 nanodevices with thickness down to 2.5 nm.We observe the quantum Griffiths singularity(QGS)of SMT in thin 4Ha-TaSe2 nanodevices by performing ultralow temperature transport measurements and activated scaling analysis.With increasing the thickness of TaSe2 nanodevice to 10.6 nm,the signature of magnetoresistance crossing region can hardly be detected,revealing the thickness dependence of SMT.In this procedure,the disorder strength plays a dominant role.This work enriches the platform for studying QGS and may stimulate further investigations on the correlation between different novel quantum phenomena in the same 2D superconducting system.

The combination of eddy thermal effect of biodegradable magnesium with immune checkpoint blockade shows enhanced efficacy against osteosarcoma

Osteosarcoma(OS)patients have a poor prognosis due to its high degree of heterogeneity and high rate of metastasis.Magnetic hyperthermia therapy(MHT)combined with immunotherapy is an effective strategy to treat solid and metastatic tumors.Here,we combined biodegradable magnesium(Mg)macroscale rods,which acted as an eddy thermo-magnetic agent under a low external alternating magnetic field,and immunotherapy to achieve a radical cure for OS.The eddy thermal effect(ETE)of the Mg rods(MgR)showed outstanding cytotoxic effects and enhanced the maturation of dendritic cells(DCs),and the mild MHT induced the immunogenic cell death(ICD)in the OS cells.Combined with immune checkpoint blockade(ICB)therapy,we obtained an excellent curative effect against OS,and a further evaluation demonstrated that the local MHT induced by the MgR increased T cells infiltration and the polarization of M1 macrophages.Interestingly,the biodegradable MgR also promoted bone osteogenesis.Our work highlighted the uneven ETE mediated by the biodegradable MgR induced a comprehensive immunologic activation in the OS tumor microenvironment(TME),which would inspire the application of MHT for the effective treatment of OS.

Enzymes immobilized in wood-derived cellulose scaffold for constructing a novel modular bioreactor

Modular bioreactors can provide a flexible platform for constructing complex multi-step pathways,which may be a solution for maximizing reactions and overcoming the complexity of multi-enzyme systems.Here,we selected wood-derived cellulose scaffold as a support for enzyme immobilization and constructed the modular bioreactor.Cellulose scaffold was prepared after removing lignin from wood,followed by citric acid functionalization and the addition of glutaraldehyde finally allowed the cross-linking of enzymes.Three enzymes,horseradish peroxidase(HRP),glucose oxidase(GOD),and catalase(CAT),were separately immobilized,resulting in the immobilized enzyme amount to over 40 mg/g.The introduction of carboxyl groups from citric acid facilitated the rapid enzyme adsorption on the support surface and immobilized enzymes possess~65%expressed activity.Modular bioreactors were constructed by using the immobilized enzymes.With the immobilized HRP module,reactor showed desired catalytic performance with the phenol degradation rate of>90%.Also,a pH regulation can occur in the bioreactors for preserving enzyme activities and neutralizing acid products.In the GOD/CAT modular bioreactor,the cascade reaction with adjusting pH values can achieve a 95%yield of sodium gluconate and exhibit a favorable reusability of 5 operation cycles.

O-glycosyltransferases from Homo sapiens contributes to the biosynthesis of Glycyrrhetic Acid 3-O-mono-β-D-glucuronide and Glycyrrhizin in Saccharomyces cerevisiae

Glycyrrhizin(GL)and Glycyrrhetic Acid 3-O-mono-β-D-glucuronide(GAMG)are the typical triterpenoid glycosides found in the root of licorice,a popular medicinal plant that exhibits diverse physiological effects and pharmacological manifestations.However,only few reports are available on the glycosylation enzymes involved in the biosynthesis of these valuable compounds with low conversion yield so far.In mammals,glycosyltransferases are involved in the phase II metabolism and may provide new solutions for us to engineer microbial strains to produce high valued compounds due to the substrate promiscuity of these glycosyltransferases.In this study,we mined the genomic databases of mammals and evaluated 22 candidate genes of O-glycosyltransferases by analyzing their catalytic potential for O-glycosylation of the native substrate,glycyrrhetinic acid(GA)for its glycodiversification.Out of 22 selected glycosyltransferases,only UGT1A1 exhibited high catalytic performance for biosynthesis of the key licorice compounds GL and GAMG.Molecular docking results proposed that the enzymatic activity of UGT1A1 was likely owing to the stable hydrogen bonding interactions and favorite conformations between the amino acid residues around substrate channels(P82~R85)and substrates.Furthermore,the complete biosynthesis pathway of GL was reconstructed in Saccharomyces cerevisiae for the first time,resulting in the production of 5.98±0.47 mg/L and 2.31±0.21 mg/L of GL and GAMG,respectively.

A flexible conductive hybrid elastomer for high-precision stress/strain and humidity detection

Flexible and environment-responsive materials are essential for a large number of applications from artificial skin to wearable devices. The present study develops a flexible, ultra-low cost conductive hybrid elastomer(CHE), which possesses high responsive capabilities to stress/strain and humidity. CHE was composed of polydimethylsiloxane(PDMS) and starch hydrogel(SH), enabling great elasticity(56 kPa),high conductivity(10^(-2)S/m) and high sensitivity to external stimuli(gauge factor of CHE under stress and strain are 0.71 and 2.22, respectively, and sensitivity to humidity is 1.2 × 10^(-6)S/m per RH%). These properties render CHE a promising candidate for artificial skin and wearable electronics applications of continuously monitoring environmental information.

Distribution pattern of the snail intermediate host of schistosomiasis japonica in the Poyang Lake region of China

Background:With the closure of the Three Gorges Dam in 2003 the hydrology of Poyang Lake was altered dramatically leading to significant changes in the environment.In order to assess the impact on schistosomiasis this study assessed the spatial and temporal patterns of the snail intermediate host,Oncomelania hupensis in the Poyang Lake tributaries.The results of the study have important implications for future snail control strategies leading to disease elimination.Methods:The marshland area surrounding Poyang Lake was divided randomly into 200×200 m vector grids using ArcGIS software,and the surveyed grids were randomly selected by the software.The snail survey was conducted in each selected grid using a survey frame of 50×50 m with one sideline of each grid serving as the starting line.No less than ten frames were used in each surveyed grid with Global Positioning System(GPS)recordings for each.All snails in each frame were collected to determine infection status by microscopy.Altitude data for all frames were extracted from a lake bottom topographic map in order to analyze the average altitude.All snail survey data were collected and statistically analyzed with SPSS 20.0 software in order to determine the difference of the percentage of frames with living snails and mean density of living snails in different regions of Poyang Lake.The altitude of the snail-infested marshlands and snail dens were subsequently identified.Results:A total of 1159 potential snail sampling grids were surveyed,of which 15231 frames(0.1 m2/frame)were investigated.1241 frames had live Oncomelania snails corresponding to 8.15%of the total number of frames.The mean density of living snails was 0.463/0.1 m2 with a maximum of 57 snails per frame.The percent of frames with snails in the southern sector(8.13%)of Poyang Lake did not differ statistically from the north(8.21%).However,the mean density of live snails in the northern sector(0.164/0.1 m2)of the lake was statistically higher(F=6.727;P=0.010)than the south(0.141/0.1 m2).In the south of the lake,the elevation of snail-inhabited marshland ranged between 11-16 m,and could be further subdivided into two snail-concentrated belts at 12-13 m of elevation and 15-16 m of elevation respectively.In the north of the lake,the elevation of snail-inhabited marshland ranged between 9-16 m with the elevation of 12-14 m being the snail-concentrated zone.Conclusions:The elevation of snail-infested marshlands in the Poyang Lake region ranged from 9 to 16 m.The snail distribution and habitat has moved north of the lake and to a lower altitude due to changes in the water level post dam closure.Based on the current geological features of the snail habitant focused mollusciciding should occur in snail dense northern regions with frequent bovine and human traffic.Targeting these identified'hotspots'of transmission will assist in elimination efforts.

A versatile photodetector assisted by photovoltaic and bolometric effects

The advent of low-dimensional materials with peculiar structure and superb band properties provides a new canonical form for the development of photodetectors.However,the limited exploitation of basic properties makes it difficult for devices to stand out.Here,we demonstrate a hybrid heterostructure with ultrathin vanadium dioxide film and molybdenum ditelluride nanoflake.Vanadium dioxide is a classical semiconductor with a narrow bandgap,a high temperature coefficient of resistance,and phase transformation.Molybdenum ditelluride,a typical two-dimensional material,is often used to construct optoelectronic devices.The heterostructure can realize three different functional modes:(i)the p-n junction exhibits ultrasensitive detection(450 nm-2μm)with a dark current down to 0.2 pA and a response time of 17μs,(ii)the Schottky junction works stably under extreme conditions such as a high temperature of 400 K,and(iii)the bolometer shows ultrabroad spectrum detection exceeding 10μm.The flexible switching between the three modes makes the heterostructure a potential candidate for next-generation photodetectors from visible to longwave infrared radiation(LWIR).This type of photodetector combines versatile detection modes,shedding light on the hybrid application of novel and traditional materials,and is a prototype of advanced optoelectronic devices.