大学新生焦虑、抑郁状况与生活行为方式的调查研究

目的了解中国大学新生焦虑、抑郁的患病率及其与多种生活行为方式之间的相关关系.方法横断面研究的数据来自2019年9-10月采集于"居民e健康"App的健康生活方式行为调查.采用自我报告的方式评估焦虑、抑郁、规律饮食、餐间零食量、水果、甜点和含糖饮料量、吸烟和二手烟暴露、饮酒、体育活动、久坐时间.社会人口统计数据包括年龄、性别、教育程度、家庭收入、宗教信仰和健康状况.采用logistic回归分析我国大学新生多种生活方式行为与焦虑、抑郁之间的关系.结果本研究共纳入1017名大学新生.大学新生的焦虑和抑郁发生率分别为40.3%和45.3%.多因素分析结果显示,宗教信仰(信仰佛教:OR=2.438,95%CI:1.097~5.421;信仰基督教:OR=5.886,95%CI:1.604~21.597)、性别(女性:OR=1.405,95%CI:1.001~1.971)、二手烟暴露(OR=1.089,95%CI:1.001~1.184)、规律饮食情况(OR=0.513,95%CI:0.346~0.759)与大学新生焦虑的发生有关.家庭收入(OR=0.732,95%CI:0.596~0.898)、规律饮食(OR=0.641,95%CI:0.415~0.990)、早餐频次(OR=0.813,95%CI:0.690~0.959)、有慢性疾病(OR=1.902,95%CI:1.335~2.712)、夜间零食量(OR=1.337,95%CI:1.108~1.612)与大学新生抑郁的发生有关.结论对大学新生的生活行为方式进行早期干预具有必要性.需要考虑大学新生的宗教信仰、健康状况和社会经济状况,改善其膳食模式,促进大学新生的健康生活行为,提高大学新生的心理健康水平.

Evolution from the Parent Mott Insulator to a Superconductor in Lightly Hole-Doped Bi2Sr2CaCu2O8+δ

High temperature superconductivity in cuprates is realized by doping the Mott insulator with charge carriers.A central issue is how such an insulating state can evolve into a conducting or superconducting state when charge carriers are introduced.Here,by in situ vacuum annealing and Rb deposition on the Bi2Sr2Ca0.6Dy0.4Cu2O8+δ(Bi2212)sample surface to push its doping level continuously from deeply underdoped(Tc=25K,doping level p^0.066)to the near-zero doping parent Mott insulator,angle-resolved photoemission spectroscopy measurements are carried out to observe the detailed electronic structure evolution in the lightly hole-doped region for the first time.Our results indicate that the chemical potential lies at about l eV above the charge transfer band for the parent state at zero doping,which is quite close to the upper Hubbard band.With increasing hole doping,the chemical potential moves continuously towards the charge transfer band and the band structure evolution exhibits a rigid band shift-like behavior.When the chemical potential approaches the charge transfer band at a doping level of^0.05,the nodal spectral weight near the Fermi level increases,followed by the emergence of the coherent quasiparticle peak and the insulator-superconductor transition.Our observations provide key insights in understanding the insulator-superconductor transition in doping the parent cuprate compound and for establishing related theories.

Unusual electronic structure of Dirac material BaMnSb_(2) revealed by angle-resolved photoemission spectroscopy

High resolution angle resolved photoemission measurements and band structure calculations are carried out to study the electronic structure of BaMnSb_(2). All the observed bands are nearly linear that extend to a wide energy range. The measured Fermi surface mainly consists of one hole pocket around Γ and a strong spot at Y which are formed from the crossing points of the linear bands. The measured electronic structure of BaMnSb_(2) is unusual and deviates strongly from the band structure calculations. These results will stimulate further efforts to theoretically understand the electronic structure of BaMnSb_(2) and search for novel properties in this Dirac material.

Evidence for bosonic mode coupling in electron dynamics of LiFeAs superconductor

Super-high resolution laser-based angle-resolved photoemission measurements are carried out on LiFeAs superconductor to investigate its electron dynamics. Three energy scales at ~ 20 meV, ~ 34 meV, and ~ 55 meV are revealed for the first time in the electron self-energy both in the superconducting state and normal state. The ~ 20 meV and ~ 34 meV scales can be attributed to the coupling of electrons with sharp bosonic modes which are most likely phonons. These observations provide definitive evidence on the existence of mode coupling in iron-based superconductors.

Development and application of simulation technique for hydrokinetic hammer

The computer simulation is an important method for hydrokinetic hammer design. Various kinds of simulation measures with their technical characters and applications being taken during the computer aided design are enumerated. Computer simulation supports plenty of valuable references to the designer. Each type of simulation process is used to explore the exact aspect of the performance of hydrokinetic hammer and each type of simulation method has its own excellences and deficiencies. Thus the integrative simulation methods based on modern computational technology are brought forward to obtain the perfect capability of the whole product. Along with the development of computer hardware and software, various kinds of platforms have been provided to different simulation methods that can be carried out with distinct working flows. The jet flow element is the core part of the hydrokinetic hammer. We can build the ideal simulation model of it by means of CFD (computational fluid dynamics) technology. On the other hand, to set up the digital model of piston and hammer, the best way is to build the virtual prototype using automatic dynamic analysis of mechanical system. As a result of the argumentation, we think the technique of Virtual Prototype and CFD are the prime way to process the combined computer simulation for hydrokinetic hammer.

A Brief Review on He Ion Irradiation Research of Steel and Iron‑Based Alloys in Nuclear Power Plants

Nuclear power plays a key role as renewable energy in alleviating the worldwide energy shortage.The material degradation caused by high-temperature and high-flux neutron irradiation is the most concerning issue for nuclear reactor safety.A large number of He atoms produced through the(n,α)transmutation reaction diffuse and migrate in metals and accumulate to form He bubbles because of the extremely low solubility of He atoms in metal materials.The helium bubbles gather at the grain boundary or grain to cause swelling,hardening,embrittlement,and other damages to the in-core structural components.This paper mainly summarizes the research progress on He irradiation in steel and iron-based alloys,including the diffusion and accumulation of He atoms,the nucleation and growth of He bubbles,and the microstructure and macroscopic degradation of material performance caused by He irradiation.The mechanism of helium irradiation-induced corrosion in steel and iron-based alloys in recent years is reviewed as well.Moreover,the investigations on irradiation performance in additive manufactured stainless steels are summarized,and the mechanism of irradiation resistance is prospected.

利用Ⅲ型聚酮合酶CsyB起始单元的底物多样性体内合成csypyrone类化合物

作为新型Ⅲ型聚酮合酶,米曲霉来源的CsyB能够依次接受一个起始单元为短链脂肪酰辅酶A、一个延伸单元为丙二酰辅酶A和另一个延伸单元为乙酰乙酰辅酶A的3个底物形成短链的csypyrone B1-3。基于CsyB的晶体结构分析,显示它的活性中心存在一个长约16?的能够接受脂肪酰辅酶A结合通道,这个通道很可能能够接受多种底物。为了检测该酶的底物多样性,将CsyB基因导入到存在长链脂肪酰辅酶A前体的大肠杆菌中表达。高效液相结果显示,相比对照菌株,重组菌株产生了一系列长链的csypyrone衍生物。利用紫外可见光特征吸收值和高分辨液相色谱-质谱联用仪对这些新产物作了初步分析。对3个具有羟基的csypyrone产物的结构进行了核磁共振一维谱和二维谱的详细鉴定,确定了其羟基的位置。上述结果显示,CsyB具有广泛的底物特异性,不但可以接受多种长链饱和或不饱和脂肪酰辅酶A,还可以接受具有羟基修饰的长链脂肪酰辅酶A作为底物。

Electronic structure of exfoliated millimeter-sized monolayer WSe2 on silicon wafer

The mono layer WSe2 is in teresting and important for future application in nanoelectronics,spintronics and valleytronics devices,because it has the largest spin splitting and Ion gest valley coherence time among all the known monolayer transition-metal dichalcogenides(TMDs).Toobtain the large-area monolayer TMDs'crystal is the first step to manu facture scalable and high-performance electronic devices.In this letter,we have successfully fabricated millimeter-sized mono layer WSe2 single crystals with very high quality,based on our improved mecha nicalexfoliation method.With such superior samples,using standard high resolution angle-resolved photoemission spectroscopy,we didcomprehe nsive electronic band structure measurements on our mono layer WSe2.The overall band features point it to be a 1.2 eV direct bandgap semico nductor.Its spin splitting of the valence band at K point is found as 460 meV,which is 30 meV less than the corresponding band splitting in its bulk counterpart.The effective hole masses of valence bands are determined as 2.344 me atГ,and 0.529 me as well as 0.532 meat K for the upper and lower branch of splitting ban ds,respectively.And screening effect from substrate is shown to substa ntially impact onthe electronic properties.Our results provide importa nt insights into band structure engineering in mono layer TMDs.Our mono layer WSe2 crystals may constitute a valuable device platform.

Development and prospect of near-field optical measurements and characterizations

扫描近地的光显微镜学(SNOM ) 是在 nano 光的大小和描述的一个理想的试验性的测量系统。除有在衍射限制以外的分辨率的显微镜学以外，有纳米分辨率的分光镜和有新奇表演的另外的仪器为在 nano 光学和 nanophotonics 的研究是不可缺少的。这篇论文考察发展中的历史近地光(NFO ) 测量方法并且在未来预见它的前景。NFO 大小的开发通过了四个阶段，包括有超级分辨率，近地的光谱学， nanooptical 参数的大小，和近地的相互作用的察觉的光成像。为每个阶段，研究目的，工艺的性质和应用程序，领域被讨论。

Emergence of superconductivity from fully incoherent normal state in an iron-based superconductor (Ba_(0.6)K_(0.4))Fe_2As_2

In unconventional superconductors, it is generally believed that understanding the physical properties of the normal state is a pre-requisite for understanding the superconductivity mechanism. In conventional superconductors like niobium or lead, the normal state is a Fermi liquid with a well-defined Fermi surface and well-defined quasipartcles along the Fermi surface. Superconductivity is realized in this case by the Fermi surface instability in the superconducting state and the formation and condensation of the electron pairs(Cooper pairing). The high temperature cuprate superconductors, on the other hand, represent another extreme case that superconductivity can be realized in the underdoped region where there is neither well-defined Fermi surface due to the pseudogap formation nor quasiparticles near the antinodal regions in the normal state. Here we report a novel scenario that superconductivity is realized in a system with well-defined Fermi surface but without quasiparticles along the Fermi surface in the normal state.High resolution laser-based angle-resolved photoemission measurements have been performed on an optimally-doped iron-based superconductor(Ba_(0.6)K_(0.4))Fe_2As_2. We find that, while sharp superconducting coherence peaks emerge in the superconducting state on the hole-like Fermi surface sheets, no quasiparticle peak is present in the normal state. Its electronic behaviours deviate strongly from a Fermi liquid system. The superconducting gap of such a system exhibits an unusual temperature dependence that it is nearly a constant in the superconducting state and abruptly closes at Tc. These observations have provided a new platform to study unconventional superconductivity in a non-Fermi liquid system.

Memory and behavior-related problems of patients with neurocognitive disorders and the attitudes of their caregivers

Objective:The purpose of this study was to investigate the memory and behavior-related problems of patients with neurocognitive disorders and the attitudes of their caregivers so as to provide an effective basis for nursing interventions against such problems.Methods:The subjects were selected from patients who were under treatment or short-term hospitalization between April 2011 and March 2012.One hundred fifty-three patients with neurocognitive disorders and their major caregivers were selected from 9 grade 3 Class A hospitals of Hunan Province.The Revised Memory and Behavior Problems Checklist(RMBPC)was used to measure the memory and behavior-related problems of patients with neurocognitive disorders and the influence on their caregivers.The occurrence of different memory and behavior-related prob-lems and the distress on their caregivers was compared.Results:The RMBPC investigation showed that among 153 patients and their caregivers,152(99.3%)had memory-related problems,137(89.5%)had depression,and 136 patients(88.9%)had destructive behaviors.The incidence of memory-related problems was higher than depression and destructive behaviors(P<0.01).Caregivers bore more distress when encountering destructive behaviors(1.95±1.13 points)than memory-related problems and depression(0.91±0.76 points and 0.89±0.85 points;P<0.01).Curve fitting was used to analyze the relationship between the number of memory and behavior-related problems and the distress on their caregivers.A curve correlation existed between the two factors(the recorded maximum value of the Cubic equation curve was 0.278,F=229.212,P<0.05).Conclusion:Among patients with neurocognitive disorders,memory-related problems had the highest incidence,while the caregivers bore the strongest distress when encountering destructive behaviors,thus interventions should be conducted in consideration of patient memory and behavior-related problems,and caregivers’attitude to further reduce caregiver burden.

Effect of Heat Treatment on the Microstructure,Mechanical Properties and Corrosion Resistance of Selective Laser Melted 304L Stainless Steel

The influence of heat treatment holding temperatures from 600 to 1300℃ on the microstructure,mechanical properties and corrosion resistance in selective laser melted(SLMed)304L stainless steel is investigated in this work.The results reveal that there is no remarkable microstructure change after holding at 600℃ for 2 h,while recrystallization leads to a slight decrease in grain size in the temperature range of 700–900℃.The heat treatment at temperatures from 1000 to 1300℃ for 2 h obviously affects the morphology of grains in SLMed 304L stainless steel.Combining effects of grain coarsening,delta-ferrite(δ)phases reduction and residual stress release during heat treatment lead to the reduction of yield strength and an increasing elongation.The elongation of the samples heat treated at 800℃ for 2 h is,however,significantly decreased due to the increase in the amount of sigma(σ)phase.A remarkable increase in the amount ofδferrite results in an increase in yield strength but a decrease in ductility after heat treatment at 1300℃ for 2 h.The corrosion resistance of the samples heat treated at 1300℃ is significantly improved due to the substantial reduction of brittle phase(σ).There is no obvious effect of the presence ofδferrite on corrosion behavior.

Ba_(0.6)K_(0.4)Fe_(2)As_(2)的精细电子结构和超导能隙

精细的电子结构和超导能隙是理解铁基超导体超导机理的前提和基础,然而,即使对于被广泛研究的最佳掺杂的Ba_(0.6)K_(0.4)Fe_(2)As_(2),其电子结构和超导能隙仍然存在不少争议.为了解决这些争议,本文利用高分辨氦灯和激光角分辨光电子能谱对最佳掺杂的Ba_(0.6)K_(0.4)Fe_(2)As_(2)进行了详细的研究,确定了r点和M点的精细电子结构和超导能隙.超导态和正常态下在M点附近作者观测到了一个小的电子型能带。和一个M型的能带δ,直接提取的超导能隙大小是5.5 meV,远远小于之前所有的ARPES测量结果.另外,作者直接观测到了超导态下和正常态下都存在r点和M点能带的复制,确定了超导态下r点附近平带的起源,是由M点e能带复制到r点的能带和p能带的超导回弯2部分组成.这些实验结果解决了关于最佳掺杂(Ba_(0.6)Ka_(0.4))Fe_(2)As_(2)的电子结构和超导能隙的一系列争议,这对于检验并建立理论来理解铁基超导体的超导机理提供了关键的信息.