Optimal parameter space for stabilizing the ferroelectric phase of Hf_(0.5)Zr_(0.5)O_(2) thin films under strain and electric fields

Hafnia-based ferroelectric materials, like Hf_(0.5)Zr_(0.5)O_(2)(HZO), have received tremendous attention owing to their potentials for building ultra-thin ferroelectric devices. The orthorhombic(O)-phase of HZO is ferroelectric but metastable in its bulk form under ambient conditions, which poses a considerable challenge to maintaining the operation performance of HZO-based ferroelectric devices. Here, we theoretically addressed this issue that provides parameter spaces for stabilizing the O-phase of HZO thin-films under various conditions. Three mechanisms were found to be capable of lowering the relative energy of the O-phase, namely, more significant surface-bulk portion of(111) surfaces, compressive c-axis strain,and positive electric fields. Considering these mechanisms, we plotted two ternary phase diagrams for HZO thin-films where the strain was applied along the in-plane uniaxial and biaxial, respectively. These diagrams indicate the O-phase could be stabilized by solely shrinking the film-thickness below 12.26 nm, ascribed to its lower surface energies. All these results shed considerable light on designing more robust and higher-performance ferroelectric devices.

Combined blasting for protection of gob-side roadway with thick and hard roof

The deformation control of surrounding rock in gobside roadway with thick and hard roof poses a significant challenge to the safety and efficiency of coal mining.To address this issue,a novel approach combining directional and non-directional blasting techniques,known as combined blasting,was proposed.This study focuses on the experimental investigation of the proposed method in the 122108 working face in Caojiatan Coal Mine as the engineering background.The initial phase of the study involves physical model experiments to reveal the underlying mechanisms of combined blasting for protecting gob-side roadway with thick and hard roof.The results demonstrate that this approach effectively accelerates the collapse of thick and hard roofs,enhances the fragmentation and expansion coefficient of gangue,facilitates the filling of the goaf with gangue,and provides support to the overlying strata,thus reducing the subsidence of the overlying strata above the goaf.Additionally,the method involves cutting the main roof into shorter beams to decrease the stress and disrupt stress transmission pathways.Subsequent numerical simulations were conducted to corroborate the findings of the physical model experiments,thus validating the accuracy of the experimental results.Furthermore,field engineering experiments were performed,affirming the efficacy of the combined blasting method in mitigating the deformation of surrounding rock and achieving the desired protection of the gob-side roadway.

Estimation of surface water content at the Tianwen-1 Zhurong landing site

China’s first Mars rover,Zhurong,successfully landed in the south of Utopia Planitia.The surface water content at the landing area can provide constraints on mineral formation conditions and help us better understand the evolution of the Martian aqueous and geological environment.In this work,the surface kinetic temperature of the Zhurong landing area was derived by analyzing data from the Mars Express Observatoire pour la Minéralogie,l’Eau,les Glaces et l’Activité(OMEGA)spectrometer.Using the Discrete Ordinate Radiative Transfer(DISORT)model,we performed atmospheric correction and thermal correction for the OMEGA data to obtain the surface effective single-particle absorption thickness(ESPAT)parameter to evaluate the surface water content.The surface water content distribution at the landing area was relatively uniform at a lateral scale of~10 km.At the Zhurong landing site,the surface water content in the topmost layer(a few hundred micrometers)of the regolith was 5−8 weight percent water(wt%H_(2)O),assuming surface particle sizes of<45μm,or 1.6−2.5 wt%H_(2)O,assuming surface particle sizes in the range of 125−250μm.The Mars Surface Composition Detector(MarSCoDe)onboard Zhurong also observed significant H_(2)O/OH signals in the landing area.Our results provide an important regional context for the hydration state of the area and can be further verified by the H content derived from the Laser-Induced Breakdown Spectrometer(LIBS)data of MarSCoDe.

脑脊液~1H-MRS对线粒体脑病的诊断价值研究

目的探讨脑脊液~1H-MRS对线粒体脑病的诊断价值,为临床诊断提供新的线索和思路。材料与方法选取经线粒体脑肌病标准评分系统确诊的13例线粒体脑病(mitochondrial disorders,ME)患者及17例临床上疑似线粒体脑病但最终确诊非线粒体病的患者为对照组,所有患者行常规MRI和~1H-MRS检查,选取MRI异常信号区(脑内无明显病变者,选取左侧基底节区为感兴趣区)、正常脑组织区及脑脊液区为感兴趣区,分别比较两组患者相应区域乳酸(Lac)峰的差异。结果脑脊液区~1H-MRS显示,10例(10/13)ME脑脊液区可见Lac峰;3例(3/17)对照组脑脊液区见Lac峰。脑内病变区~1H-MRS显示,5例(5/12)线粒体脑病患者病变区可见Lac峰,7例(7/12)病变区未见Lac峰,无病变者左侧基底节区未见Lac峰;6例(6/16)对照组病变区可见异常升高的Lac峰。脑脊液区~1H-MRS出现Lac峰诊断线粒体脑病的灵敏度、正确指数、阳性似然比、阴性似然比、符合率均优于病灶区。联合脑脊液区与病灶区~1H-MRS诊断线粒体脑病分析,相比于单独脑脊液区~1H-MRS结果,串联试验的灵敏度降低,特异度升高;并联试验灵敏度不变,特异度降低。串联、并联试验的正确指数及符合率均低于脑脊液区。结论线粒体脑病NAA峰降低、Cho峰升高无特异性,与其它非线粒体脑病难以鉴别;脑脊液区~1H-MRS出现Lac峰对线粒体脑病的诊断价值优于脑内病变区,有助于对脑脊液乳酸水平的检测。

加强感染科规范化培训学员的影像医学教学

目的提高感染科住培学员(住院医师规范化培训学员)医学影像知识的运用能力。方法(1)住培学员在进入感染科临床工作初期就如何选择正确的影像检查方式进行培训;(2)邀请影像科老师按照不同组织、器官正常影像表现,常见典型疾病影像表现,常见感染性疾病的影像表现进行分层次专题讲座;(3)安排感染科住培学员在影像科轮转,参与影像科的临床实践;(4)将"影像实战"教学方法应用于住培学员的临床实际工作中。结果感染科住培学员在完成规范化培训时都能正确选择医学影像检查方法,正确解读影像检查报告。结论医学影像知识运用能力的系统培训能提高感染科住培学员的综合临床水平。

高年级医学生医院感染防控知识及意识调查

目的了解刚刚进入临床实习的医学生医院感染防控意识的强弱及对医院感染防治知识的掌握程度。方法选取2018年3月—2019年1月期间首次进入感染科见习的165名医学生为研究对象,调查他们第一次接触感染科患者前后的手卫生消毒情况,随后进行医院感染预防与控制基础知识测试,测试内容涵盖医院感染的基本概念、消毒隔离的基本知识、一次性使用医疗用品及医疗废物的管理、职业暴露与标准预防及手卫生规范等相关知识点。结果仅有15.76%的医学生在接触患者前后都进行了规范手卫生消毒,医院感染防控知识测试优良率为53.33%。结论高年级医学生的医院感染预防与控制意识比较薄弱,相关知识掌握不牢靠。

机器视觉识别袜品纹理与精准定位的测控装置

袜品生产属于劳动密集型行业,袜品的裁剪是非常重要的工序之一,目前主要依靠人工裁剪实现,存在工作强度大、效率低、人工成本高等问题,已经制约织袜行业的良性发展。设计和实现一种机器视觉识别袜品纹理与精准定位的测控装置,该装置利用光学成像技术和快速图像采集技术实时获取袜品纹理的动态数字图像,通过提出的Gabor能量积分算法和动态延时定位指令输出方法处理后,实现对袜品特定位置裁剪的精准快速识别定位。经过实际使用验证,该装置裁剪定位精度为±2mm,高于人工裁剪精度,可完全取代人工裁剪方式。一套装置可完成相当于3个工人的工作量,在大幅度提高生产效率的同时降低企业运营成本。

适用于新能源并网变压器匝间故障识别的新判据

为增加功率输送能力,新能源并网变压器采用两电压等级三绕组、接线形式为星角角的变压器。变压器在低压侧发生匝间故障时,差动保护灵敏度不足,同时变压器空载合闸于匝间故障时,涌流闭锁判据会闭锁差动保护,延长故障切除时间。基于星角角接线型式的新能源并网变压器零序等值回路,文中通过建立零序节点电压方程,利用区外故障及匝间故障节点电压方程特征构建匝间故障识别判据,该判据与差动保护原理相比,不受励磁涌流的影响,具有较高的可靠性及速动性。文中利用实时数字仿真系统(RTDS)进行故障仿真,验证新判据的有效性及可靠性,发现采用新判据能够可靠灵敏地识别变压器匝间故障,弥补差动保护的不足。

CD24 genetic variants contribute to overall survival inpatients with gastric cancer

AIM: To investigate the role of single nucleotide polymorphisms(SNPs) in CD24 gene in susceptibility and overall survival of gastric cancer(GC).METHODS: We genotyped 3 tagging SNPs of CD24-P-534 in the promoter region, P170 in the coding region of exon 2 and P1527 in the 3′ untranslated region- using polymerase chain reaction-restriction fragment length polymorphism in specimens from 679 histologically-confirmed GC cases, 111 gastric atrophy(GA) cases and 976 tumor-free controls. Serumimmunoglobulin G antibodies to Helicobacter pylori(H. pylori) of all subjects were detected by enzyme-linked immunosorbent assay. CD24 expression was evaluated by immunohistochemistry in 131 GC specimens. Correlations between SNPs and risk of GC or GA were shown by P values and odd ratios(ORs) with 95% confidence intervals(95%CI) compared with the most common genotype of each SNP using the unconditional logistic regression model after adjusting for age, sex and H. pylori infection. Survival within each SNP group was plotted by Kaplan-Meier method and compared by log-rank test(recessive model). Hazard ratios with 95%CIs were computed by Cox regression model after adjusting for age, sex, histological type, tumor differentiation, clinical stage and post-operational chemotherapy.RESULTS: All of the three loci were in Hardy-Weinberg equilibrium in the control group. Median followup time for the 600 GC patients included in the survival analysis was 36.2 mo(range, 2.1-66.7 mo; 95%CI: 34.3-36.5 mo). Patients with the P-534 A/A genotype had significantly shorter survival(HR = 1.38, 95%CI: 1.01-1.88, P = 0.042) than did the C/C or C/A genotype carriers after adjusting for age, sex, histological type, tumor differentiation, clinical stage and post-operational chemotherapy. This trend was more evident in patients who lived longer than 2.5 years(HR = 7.55, 95%CI: 2.16-26.32, P = 0.001). The P170 T/T genotype was associated with a shorter lifespan than the non-T/T genotypes, but not significantly so. None of the three genetic variants was found to be associated with risk of GC(including tumor stage, grade and distant metastasis) or with risk of gastric atrophy. Furthermore, no difference of CD24 expression was found among the genotypes.CONCLUSION: The P-534 site in CD24 gene affects the overall survival of gastric cancer and may serve as a prognostic marker for gastric cancer.

Substrates and interlayer coupling effects on Mo1-xWxSe2 alloys

Two-dimensional(2D) transition metal dichalcogenides alloys are potential materials in the application of photodetectors over a wide spectral range due to their composition-dependent bandgaps. The study of bandgap engineering is important for the application of 2D materials in devices. Here, we grow the Mo1-xWxSe2 alloys on mica, sapphire and SiO2/Si substrates by chemical vapor deposition(CVD) method. Mo1-x Wx Se2 alloys are grown on the mica substrates by CVD method for the first time. Photoluminescence(PL) spectroscopy is used to investigate the effects of substrates and interlayer coupling force on the optical bandgaps of as-grown Mo1-xWxSe2 alloys. We find that the substrates used in this work have an ignorable effect on the optical bandgaps of as-grown Mo1-xWxSe2. The interlayer coupling effect on the optical bandgaps of as-grown Mo1-xWxSe2 is larger than the substrates effect. These findings provide a new way for the future study of the growth and physical properties of 2D alloy materials.

A review of in situ transmission electron microscopy study on the switching mechanism and packaging reliability in non-volatile memory

Non-volatile memory(NVM)devices with non-volatility and low power consumption properties are important in the data storage field.The switching mechanism and packaging reliability issues in NVMs are of great research interest.The switching process in NVM devices accompanied by the evolution of microstructure and composition is fast and subtle.Transmission electron microscopy(TEM)with high spatial resolution and versatile external fields is widely used in analyzing the evolution of morphology,structures and chemical compositions at atomic scale.The various external stimuli,such as thermal,electrical,mechanical,optical and magnetic fields,provide a platform to probe and engineer NVM devices inside TEM in real-time.Such advanced technologies make it possible for an in situ and interactive manipulation of NVM devices without sacrificing the resolution.This technology facilitates the exploration of the intrinsic structure-switching mechanism of NVMs and the reliability issues in the memory package.In this review,the evolution of the functional layers in NVM devices characterized by the advanced in situ TEM technology is introduced,with intermetallic compounds forming and degradation process investigated.The principles and challenges of TEM technology on NVM device study are also discussed.

基于端羟基聚丁二烯聚氨酯型UV减粘胶的合成与性能

先以端羟基聚丁二烯与异佛尔酮二异氰酸酯反应,然后以1,4-丁二醇或1,4-丁烯二醇为扩链剂进行扩链,控制主链中C=C含量,并添加二官能度或三官能度的丙烯酸酯交联单体,制备了聚氨酯型紫外(UV)减粘胶。采用傅里叶变换红外光谱表征了减粘胶的分子结构;考察了交联程度对减粘效果的影响。结果表明,随着减粘胶交联密度、凝胶率的增加,减粘胶的体积收缩率增大,进而表面粗糙度增加,减粘效果明显。当以1,4-丁烯二醇为扩链剂、三羟甲基丙烷三丙烯酸酯(TMPTA)为可交联单体所得的减粘胶UV照射前的剥离力达19 N/25 mm,UV照射后的剥离力降低至0.2N/25 mm,满足使用要求。

Prolonged propagation of rat neural stem cells relies on inhibiting autocrine/paracrine bone morphogenetic protein and platelet derived growth factor signals

Continuous expansion of rat neural stem cell lines has not been achieved due to proliferation arrest and spontaneous differentiation in vitro. In the current study, neural precursor cells derived from the subventricular zone of adult rats spontaneously underwent astroglial and oligodendroglial differentiation after limited propagation. This differentiation was largely induced by autocrine or paracrine bone morphogenetic protein and platelet derived growth factor signals. The results showed that, by inhibiting bone morphogenetic protein and platelet derived growth factor signals, adult rat neural precursor cells could be extensively cultured in vitro as tripotent stem cell lines. In addition to adult rat neural stem cells, we found that bone morphogenetic protein antagonists can promote the proliferation of human neural stem cells. Therefore, the present findings illustrated the role of autocrine or paracrine bone morphogenetic protein and platelet derived growth factor signaling in determining neural stem cell self-renewal and differentiation. By antagonizing both signals, the long-term propagation of rat neural stem cell lines can be achieved.

Raman spectroscopy characterization of two-dimensional materials

Two-dimensional （2D） materials have become a hot study topic in recent years due to their outstanding electronic, optical, and thermal properties. The unique band structures of strong in-plane chemical bonds and weak out-of-plane van der Waals （vdW） interactions make 2D materials promising for nanodevices and various other applications. Raman spectroscopy is a powerful and non-destructive characterization tool to study the properties of 2D materials. In this work, we review the research on the characterization of 2D materials with Raman spectroscopy. In addition, we discuss the application of the Raman spectroscopy technique to semiconductors, superconductivity, photoelectricity, and thermoelectricity.

An Efficient Bio-inspired Oxygen Reduction Reaction Catalyst:MnO_(x)Nanosheets Incorporated Iron Phthalocyanine Functionalized Graphene

Oxygen reduction reaction(ORR)catalysts play a critical role in energy storage and conversion devices and have been attracted enormous interests,and however,it remains challenging to develop highly active cheap catalysts in a simple and green route.Inspired by the heme-copper oxidases(HOCs),in which the ORR active center is originated from the incorporation of Fe-N_(4)with copper atom,we here developed a fine manganese oxide nanosheets(MnO_(x)NSs)integrated with iron phthalocyanine(FePc)anchored on highly conductive graphene(MnO_(x)/FePc-G)through a green route only involve ethanol as the reagent.The bio-inspired catalyst MnO_(x)/Fe Pc-G demonstrated high ORR activity with a half-wave potential(E_(1/2))of 0.887 V,about 57 mV more positive than that of Pt/C.And the current density(j)at 0.9 V is about 1.9 m A cm^(-2),which is three times of Pt/C and FePc-G.More importantly,the bio-inspired systems show superior stability in comparison to commercial Pt/C,showing a potential of 0.863 V to deliver a j of 3 mA cm^(-2)after 18000 s polarization,about 80 mV higher than that of 0.783 V for Pt/C.The high activity is contributed by the integration of the Fe Pc and MnO_(x)NSs that plays the role to assist the cleavage of the O_(2)bond.Our approach provides a new evidence to develop highly efficient ORR catalysts through imitate the naturally involved systems through a simple route.

变压器过励磁五次谐波特征及机制的研究

现代大型变压器正常运行时磁感应强度取值较大,在短时过电压(过励磁)时,变压器励磁电流将激增,很容易造成差动保护误动,在过电压倍数不大的情况下很有必要利用励磁电流的谐波含量对差动保护进行闭锁。利用两条不同斜率的折线对变压器磁化特性曲线进行拟合,在此基础上推导了励磁电流五次谐波与变压器过电压值的关系表达式,并在电磁暂态仿真软件PSCAD/EMTDC中搭建变压器过励磁模型,对比了理论推导与仿真波形,验证了理论公式的正确性,并对过电压条件下变压器保护五次谐波闭锁定值进行了探讨。

Outcomes of chronic angle-closure glaucoma treated by phacoemulsification and endocyclophotocoagulation with or without endoscopically goniosynechialysis

AIM:To investigate the surgical outcomes of patients with chronic angle-closure glaucoma(CACG)treated with phacoemulsification(phaco)/endocyclophotocoagulation(ECP)with and without endoscopic goniosynechialysis(E-GSL).METHODS:A retrospective,nonrandomized,comparative case series was conducted.Patients with CACG who underwent phaco in combination with either ECP alone(ECP group)or GSL with ECP(E-GSL group)from 2018 to 2019 were followed for 12mo and reviewed.Clinical features and outcomes were identified and analyzed.The ECP and E-GSL groups were matched in age and baseline intraocular pressure(IOP).Changes in IOP,mean of visual acuity(VA),peripheral anterior synechiae(PAS)formation,and the number of glaucoma medications was examined.RESULTS:The ECP group included 32 eyes of 27 patients,and the E-GSL group included 32 eyes of 26 patients.The preoperative baseline IOP was 22.18±6.48 mm Hg in the ECP group and 22.95±6.71 mm Hg in the E-GSL group(P=0.644).The mean IOP reduction was 26.2%in the ECP group and 41.6%in the E-GSL group at 12mo.The mean postoperative VA(log MAR units)at 12mo was 0.47 in the ECP group and 0.36 in the E-GSL group.The reduction in PAS formation and the number of glaucoma medications was also higher in the ECP group than E-GSL group at 12mo.CONCLUSION:The phaco/ECP and phaco/E-GSL groups both achieve a significant reduction in IOP without complications associated with traditional glaucoma filtration surgeries.

Tuning the Electrochemical Property of the Ultrafine Metal-oxide Nanoclusters by Iron Phthalocyanine as Efficient Catalysts for Energy Storage and Conversion

Nanoclusters(NCs)have been demonstrated of outstanding performance in electrochemical energy storage and conversion technologies due to their strong quantum confinement effects and strong interaction with supports.Here,we developed a class of ultrafine metal-oxide(MOx,M=Fe,Co and Ni)NCs incorporated with iron phthalocyanine(FePc),MOx/FePc-G,supported on graphene as high-performance catalysts for oxygen reduction reaction(ORR),oxygen evolution reaction(OER),and carbon dioxide reduction(CO2RR).The high activities for ORR and OER are attributed to the electron donation and accepting ability of the highly redox active of FePc-G that could tune the properties of MOx.The FeOx/FePc-G exhibits an extremely positive half-wave potential(E1/2)of 0.888 and 0.610 V for ORR in alkaline and neutral conditions,respectively,which is around 60 mV more positive than that of Pt/C.And NiOx/FePc-G shows similar OER activity with the state-of-the-art catalysts,Ir/C,and better performance than NiFeO NCs supported on graphene.Remarkably,the CoOx/FePc-G and NiOx/FePc-G show high activity and selectivity to reduce CO2 into CO with a low onset potential of-0.22 V(overpotential is 0.11 V).

Research on Microgrid and its Application in China

This paper presents the state of the art research and application of microgrid in China, and then introduces the major concerns for the development of microgrid. The research related to microgrid inChinaarose around 2004, focused on the connection of distributed energy resources (DERs) to grid and its influence on distribution network, and then followed the microgrid concept of Consortium for Electric Reliability Technology Solutions (CERTS). However, the microgrid inChinahas taken a more active path with the development of DER and the encouragement of the development of smart grid and resource and energy needing. Now, nearly every province inChinahas typical researches and applications of microgrid. Besides, there are already two major patterns in the development of microgrid, the institute-domi- nating research and the enterprise-dominating application. Research institutions likeTianjinUniversity, Hefei University of Technology, Xi’an Jiaotong University,InstituteofElectrical Engineering(ChineseAcademyof Sciences), etc., are leading the research on microgrid. The companies like State Grid Corporation of China (SGCC), China Southern Power Grid (CSPG), etc., have accomplished several demonstration projects of microgrid, and give a further boost to its application. At the end of the paper, according to the present situation of the development of microgrid inChina, the facing problems and the way to deal with it are put forward.

Effect of butylphthalide soft capsule on the anti-inflammatory effect and plaque stability in patients with ischemic cerebrovascular disease and carotid atherosclerosis

Objective:To explore the effect of butylphthalide soft capsule on the serum hs-CRP, MMP-9, and TNF-α in patients with ischemic cerebrovascular disease in order to evaluate the the therapeutic effect in the treatment of carotid atherosclerosis.Methods:According to the carotid ultrasound results, the patients were divided into the stable plaque group (control group) and the vulnerable plaque group. The patients in the vulnerable plaque group were randomized into the intervention 1 group and intervention 2 group. The patients in the two subgroups were given bayaspirin and atorvastatin. On this basis, the patients in the intervention 1 group were given butylphthalide soft capsules. The serum hs-CRP, MMP-9, and TNF-αbefore treatment and 6 months after treatment in each group were detected. The color Doppler ultrasound was used to measure and evaluate IMT, Crouse score, and plaque echo change. Results: The serum hs-CRP, MMP-9, and TNF-α levels before treatment between the two subgroups were significantly higher than those in the control group, but the comparison between intervention 1 group and intervention 2 group was not statistically significant. The serum hs-CRP, MMP-9, and TNF-α levels 6 months after treatment in the two subgroups were significantly reduced when compared with before treatment. The serum hs-CRP, MMP-9, and TNF-α levels after treatment in the intervention 1 group were significantly lower than those in the intervention 2 group. IMT 6 months after treatment in the two subgroups was significantly reduced when compared with before treatment. The reduced degree of IMT after treatment in the intervention 1 group was significantly greater than that in the intervention 2 group. Crouse score after treatment in the two subgroups was significantly reduced when compared with before treatment, but the comparison between the two groups was not statistically significant. The unstable plaque number after treatment in the two subgroups was significantly reduced when compared with before treatment. The unstable plaque number after treatment in the intervention 1 group was significantly lower than that in the intervention 2 group.Conclusions:Butylphthalide soft capsule can resist the inflammation, reverse the prolieration of carotid intima, stabilize the vulnerable plaque, and remove the non-atherosclerotic plaque.