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Hidden spin polarization in the 1T-phase layered transition-metal dichalcogenides MX_2(M = Zr, Hf; X = S, Se, Te)

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Science Bulletin 2018年第2期63卷 85-91页

作者： Cai Cheng Jia-Tao Sun Xiang-Rong Chen sheng meng Institute of Atomic and Molecular Physics College of Physical Science and Technology Sichuan University Institute of Physics Chinese Academy of Sciences

The recent discovery of hidden spin polarization emerging in layered materials of specific nonmagnetic crystal is a fascinating phenomenon, though hardly explored yet. Here, we have studied hidden spin tex- tures in layered nonmagnetic 1 T-phase transition-metal dichalcogenides MX2 （M = Zr, Hf; X = S, Se, Te） by using first-principles calculations. Spin-layer locking effect, namely, energy-degenerate opposite spins spatially separated in the top and bottom layer respectively, has been identified. In particular, the hidden spin polarization of 13-band can be easily probed, which is strongly affected by the strength of spin-orbit coupling. The hidden spin polarization of k-band locating at high symmetry M point （conduction band minimum） has a strong anisotropy. In the bilayer, the hidden spin polarization is preserved at the upmost Se layer, while being suppressed if the ZrSe2 layer is taken as the symmetry partner. Our results on hidden spin polarization in 1 T-phase dichalcogenides, verifiable by spin-resolved and angle-resolved photoemis- sion spectroscopy （ARPES）, enrich our understanding of spin physics and provide important clues to search for specific spin polarization in two dimensional materials for spintronic and quantum informa- tion applications.

关键词： Hidden spin polarizationTransition-metal dichalcogenides 1T-phaseHelical spin textureCentrosymmetric

Strong quartic anharmonicity,ultralow thermal conductivity,high band degeneracy and good thermoelectric performance in Na_(2)TlSb

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npj Computational Materials 2023年第1期9卷 2167-2175页

作者： Tongcai Yue Yinchang Zhao Jun Ni sheng meng Zhenhong Dai Department of Physics Yantai UniversityYantai 264005P.R.China Department of Physics Tsinghua UniversityBeijing 100084P.R.China Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190P.R.China Collaborative Innovation Center of Quantum Matter Beijing 100084P.R.China

We employ first-principles calculations combined with self-consistent phonon theory and Boltzmann transport equations to investigate the thermal transport and thermoelectric properties of full-Heusler compound Na_(2)*** findings exhibit that the strong quartic anharmonicity and temperature dependence of the Tl atom with rattling behavior plays an important role in the lattice stability of Na_(2)*** find that soft Tl-Sb bonding and resonant bonding in the pseudocage composed of the Na and Sb atoms interaction is responsible for ultralowκ***,the multi-valley band structure increases the band degeneracy,results in a high power factor in p-type Na_(2)*** coexistence of ultralowκL and high power factor presents that Na_(2)TlSb is a potential candidate for thermoelectric ***,these findings help to understand the origin of ultralowκL of full-Heusler compounds with strong quartic anharmonicity,leading to the rational design of full-Heusler compounds with high thermoelectric performance.

关键词： harmonic bonding thermal

Effect of Nb Content on the Hot Deformation Behavior of S460ML Steel

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Acta Metallurgica Sinica(English Letters) 2019年第4期32卷 526-534页

作者： Yu-Cheng Zhang Zhen-sheng meng Yang meng Xin-Hua Ju Zhong-Hang Jiang Ze-Jun Ma Research Institute of Technology of Shougang Group Co.Ltd.

The hot deformation behavior of S460 ML steel with different Nb contents was investigated by single-pass compression experiment on the Gleeble-1500 thermo-machine simulator at deformation temperatures ranging from 900 to 1200 ℃ and strain rates from 0.1 to 5.0 s^(-1). The critical strain of dynamic recrystallization(DRC) under different conditions was determined by using working hardening rate-strain curves. The relationship between critical strain and peak strain of DRC was discussed. By means of regression analysis method, the hot deformation activation energy of steels and the mathematical model for predicting DRC critical strain were calculated and established, respectively. The results showed that DRC occurred during hot deformation. As the deformation temperature increased and strain rate decreased, the critical strain of DRC decreased. The critical strain(εc) showed linear relationship with peak strain(εp). As Nb content increased,the needed deformation temperature for occurring DRC increased, while the needed strain rate for it decreased. The activation energy for hot deformation of S460 ML steel increased with increasing Nb content.

关键词： Dynamic recrystallization Critical strain Nb content Deformation temperature Strain rate Hot deformation

Water on surfaces from first-principles molecular dynamics

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Chinese Physics B 2020年第11期29卷 37-43页

作者： Peiwei You Jiyu Xu Cui Zhang sheng meng Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Collaborative Innovation Center of Quantum Matter Beijing 100190China

Water is ubiquitous and so is its presence in the proximity of *** determine and control the properties of interfacial water molecules at nanoscale is essential for its successful applications in environmental and energy-related *** is very challenging to explore the atomic structure and electronic properties of water under various conditions,especially at the *** we review recent progress and open challenges in describing physicochemical properties of water on surfaces for solar water splitting,water corrosion,and desalination using first-principles approaches,and highlight the key role of these methods in understanding the complex electronic and dynamic interplay between water and *** aim at showing the importance of unraveling fundamental mechanisms and providing physical insights into the behavior of water on surfaces,in order to pave the way to water-related material design.

关键词： first-principles molecular dynamics water at surfaces reaction mechanism

Two-dimensional silicon-carbon hybrids with a honeycomb lattice: New family for two-dimensional photovoltaic materials

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Science China(Physics,Mechanics & Astronomy) 2015年第10期58卷 81-88页

作者： ZHANG Jin REN Jun FU HuiXia DING ZiJing LI Hui meng sheng Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Department of Physics Tsinghua University Collaborative Innovation Center of Quantum Matter

We predict a series of new two-dimensional(2D) inorganic materials made of silicon and carbon elements(2D SixC1?x) based on density functional theory. Our calculations on optimized structure, phonon dispersion, and finite temperature molecular dynamics confirm the stability of 2D SixC1?x sheets in a two-dimensional, graphene-like, honeycomb lattice. The electronic band gaps vary from zero to 2.5 e V as the ratio x changes in 2D SixC1?x changes, suggesting a versatile electronic structure in these sheets. Interestingly, among these structures Si0.25C0.75 and Si0.75C0.25 with graphene-like superlattices are semimetals with zero band gap as their ? and ?* bands cross linearly at the Fermi level. Atomic structural searches based on particle-swarm optimization show that the ordered 2D SixC1?x structures are energetically favorable. Optical absorption calculations demonstrate that the 2D silicon-carbon hybrid materials have strong photoabsorption in visible light region, which hold promising potential in photovoltaic applications. Such unique electronic and optical properties in 2D SixC1?x have profound implications in nanoelectronic and photovoltaic device applications.

关键词： 2D Si-C hybrids electronic structure photovoltaic materials first-principles calculations

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复杂结构井旋转下套管数学模型建立与分析

科学技术与工程 2024年第5期24卷 1870-1877页

作者：杨谋王鑫宇蒲欢李郑涛吴双胥猛生西南石油大学油气藏地质及开发工程全国重点实验室成都610500 中国石油西南油气田公司工程技术研究院成都618300 中国石油川渝页岩气前线指挥部成都610056 塔里木油田英买采油气管理区巴音郭楞841599

随着复杂结构井钻井技术发展,井斜角和方位角随着井深复杂变化引起常规套管下入方式难度大,旋转下套管技术可有效解决套管下入的难题,但该方面的理论模拟分析报道较少,增加了旋转下套管技术应用的盲目性和低效性。综合运用软杆和刚杆模... 详细信息

随着复杂结构井钻井技术发展,井斜角和方位角随着井深复杂变化引起常规套管下入方式难度大,旋转下套管技术可有效解决套管下入的难题,但该方面的理论模拟分析报道较少,增加了旋转下套管技术应用的盲目性和低效性。综合运用软杆和刚杆模型的优点并考虑井眼轨迹对模型计算条件影响,建立了旋转下套管数学模型;结合实例井对比了大钩载荷和模拟的轴向应力,验证了模型的正确性;在此基础上,探讨了常规和不同旋转速度下套管的摩阻,并分析了不同摩阻系数条件下的摩阻分布特征。实例分析表明:相同井深下,旋转下套管摩阻小于常规下套管摩阻,并且旋转速度越快,下套管摩阻越小;当旋转速度分别为15 r/min和20 r/min时,井底处摩阻降低幅度分别为12.13%和19.17%;造斜率越大,摩阻越高,导致套管下入到指定深度难度加大;钻井液摩阻系数越大,套管下入难度越高;在井深1 401.5 m,裸眼段摩阻系数分别为0.21和0.29,常规下套管摩阻分别为46.51 kN和57.49 kN。该模型能准确预测下套管摩阻,对复杂结构井的套管下入具有指导意义。

关键词：复杂结构井套管摩阻旋转下套管摩阻计算模型摩阻分布特征

谷子SiPHYA和SiPHYB基因对光质、光周期和非生物胁迫的响应

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农业生物技术学报 2024年第5期32卷 983-994页

作者：杜晓芬沈蒙蒙王智兰韩康妮李颜方成锴李禹欣连世超王军山西农业大学谷子研究所/山西省后稷实验室山西农业大学农学院

光敏色素是一类红光/远红光受体，调控植物种子萌发、株高、开花和避荫性。为探究谷子(Setaria italica)光敏色素A (phytochromes A, PHYA)和光敏色素B (PHYB)基因对光质、光周期和非生物胁迫的响应模式，本研究采用RT-PCR克隆得到SiPHY... 详细信息

光敏色素是一类红光/远红光受体，调控植物种子萌发、株高、开花和避荫性。为探究谷子(Setaria italica)光敏色素A (phytochromes A, PHYA)和光敏色素B (PHYB)基因对光质、光周期和非生物胁迫的响应模式，本研究采用RT-PCR克隆得到SiPHYA (Seita.9G113600)和SiPHYB (Seita.9G427800)的c DNA序列，SiPHYA编码区长度为3 396 bp，编码1 131个氨基酸；SiPHYB编码区长度为3 507 bp，编码1 169个氨基酸。利用MEGA-X软件构建多物种进化树，谷子SiPHYA和SiPHYB分别与玉米(Zea mays)ZmPHYA和ZmPHYB亲缘关系最近。通过在线网站植物转录调控图谱(plant transcriptional regulatory map, PlantRegMap, http://***/***)预测SiPHYA和SiPHYB启动子区结合转录因子情况，结果显示，29个家族共计109个转录因子可结合到SiPHYA启动子区，27个家族共计93个转录因子可结合到SiPHYB启动子区。最后利用qRT-PCR研究其在谷子不同组织器官及不同光质、光周期和逆境处理下的表达模式。结果表明，SiPHYA和SiPHYB在谷子的根、茎、叶和幼穗中均有表达，且都在旗叶中表达量最高；不同光质处理下，SiPHYA和SiPHYB在'衡谷12号'和'长农35号'中响应模式有所不同。其中，'衡谷12号'中SiPHYA在黑暗下表达量最高，而'长农35号'中SiPHYA在远红光下表达量最高，SiPHYB在'衡谷12号'和'长农35号'中均表现为白光下表达量最高，红光下表达量最低；长日照条件下，SiPHYA在'衡谷12号'和'长农35号'中均表现出相似的昼夜节律变化，SiPHYB在'长农35号'中表现出昼夜节律变化，但在'衡谷12号'中无昼夜节律变化；短日照条件下，SiPHYA和SiPHYB在'衡谷12号'和'长农35号'中均无昼夜节律变化；SiPHYA和SiPHYB对高盐、高热、低温和干旱均有响应，但响应模式有所不同。本研究为深入挖掘SiPHYA和SiPHYB在谷子生长发育和非生物胁迫中的功能机制提供线索，并为其在谷子分子遗传改良中的应用提供依据。

关键词：谷子光敏色素光质光周期逆境胁迫表达分析

Basic science of water： Challenges and current status towards a molecular picture

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Nano Research 2015年第10期8卷 3085-3085,3086-3110页

作者： sheng meng Lauren F. Greenlee Yuen Ron Shen Enge Wang BeijingNationalLabforCondensedMatterPhysics InstituteofPhysicsChineseAcademyofSciencesBeijing100190China AppliedChemicalsandMaterialsDivision NationalInstituteofStandardsandTechnology325BroadwayMS647BoulderCO80305USA DepartmentofPhysics UniversityofCaliforniaBerkeleyCA94720USA InternationalCenterforQuantumMaterials SchoolofPhysicsPekingUniversityBeijing100871China

Rapid developments in both fundamental science and modern technology that target water-related problems, including the physical nature of our planet and environment, the origin of life, energy production via water splitting, and water purification, all call for a molecular-level understanding of water. This invokes relentless efforts to further our understanding of the basic science of water. Current challenges to achieve a molecular picture of the peculiar properties and behavior of water are discussed herein, with a particular focus on the structure and dynamics of bulk and surface water, the molecular mechanisms of water wetting and splitting, application-oriented research on water decontamination and desalination, and the development of complementary techniques for probing water at the nanoscale.

关键词： water molecular structure surface water water treatment nanotechnology water properties

肺炎患儿血清炎症指标水平与心肌损害程度的相关性分析

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医药论坛杂志 2024年第12期45卷 1267-1271页

作者：孟永胜刘亚娜石宏开封市中心医院儿科二病区河南开封475000

目的探讨肺炎患儿降钙素原(PCT)、白介素-6(IL-6)、超敏C-反应蛋白(hs-CRP)与心肌损害程度的相关性。方法选取2020年4月至2023年4月开封市中心医院收治的153例肺炎患儿,按其住院期间是否发生心肌损害分为MD组(93例)与非MD组(60),其中MD... 详细信息

目的探讨肺炎患儿降钙素原(PCT)、白介素-6(IL-6)、超敏C-反应蛋白(hs-CRP)与心肌损害程度的相关性。方法选取2020年4月至2023年4月开封市中心医院收治的153例肺炎患儿,按其住院期间是否发生心肌损害分为MD组(93例)与非MD组(60),其中MD组患儿美国纽约心脏病学会(NYHA)心功能分级Ⅱ级37例,Ⅲ级31例,IV级25例。比较两组一般资料及PCT、IL-6、hs-CRP水平;分析PCT、IL-6、hs-CRP不同NYHA分级、肌钙蛋白或肌酸激酶同工酶的相关性;采用ROC分析各变量预测心肌损害的效能。结果MD组肌钙蛋白(156.92±43.95)pg/mL、肌酸激酶同工酶(56.92±13.47)U/L高于非MD组(73.27±14.94)pg/mL、(18.47±3.59)U/L,住院时间(13.48±3.35)d长于非MD组(9.36±2.57)d(P<0.05);MD组PCT(10.58±1.48)pg/L、IL-6(293.27±78.28)pg/mL、hs-CRP(16.37±3.22)mg/mL高于非MD组(7.13±1.26)pg/L、(215.28±56.93)pg/mL、(9.74±1.47)mg/mL(P<0.05);NYHA IV组患儿PCT(16.27±1.37)pg/L、IL-6(336.83±57.84)pg/mL、hs-CRP(21.97±4.95)mg/mL高于Ⅲ级患儿(12.39±1.64)pg/L、(289.37±66.82)pg/mL、(17.94±2.69)mg/mL,Ⅲ级患儿高于Ⅱ级患儿(7.67±1.39)pg/L、(243.34±59.47)pg/mL、(12.34±3.59)mg/mL(P<0.05);相关分析显示,PCT、IL-6、hs-CRP与肌钙蛋白呈正相关(r=0.572、0.482、0.588,P<0.05)、与肌酸激酶同工酶呈正相关(r=0.536、0.513、0.567,P<0.05);ROC分析显示,PCT预测肺炎患儿心肌损害的AUC值为0.875、最佳截断值为9.72 pg/L、灵敏度为82.85%、特异度为86.79;IL-6 AUC值为0.819,最佳截断值为258.64 pg/mL,灵敏度为76.59%,特异度为82.54%;hs-CRP AUC值为0.853,最佳截断值为14.27 mg/mL,灵敏度为81.73%,特异度为84.67%;三者联合AUC值为0.943,灵敏度为93.73%,特异度为94.73%。结论PCT、IL-6、hs-CRP与肺炎患儿心肌损害程度存在相关性,可作为预测心肌损害的参考指标。

关键词：肺炎儿科心肌损害心功能炎症指标 ROC分析