贵溪冶炼厂周边土壤重金属污染分析与生态风险评价

采集了贵溪冶炼厂附近3类典型重金属污染土壤:未受任何修复土壤(A)、正在进行植物修复的土壤(B)和已受植物修复的土壤(C),测定和分析了土壤的理化性质和重金属总量,采用单因子污染指数法和内梅罗综合指数法对该土壤进行了评价,Hakanson潜在生态风险评价法评估了该土壤中重金属的潜在生态危害。结果表明:修复前,土壤综合污染指数P综=15.24,土壤属重度污染,具有极强的综合危害性;Zn、Cd、Cu、As、Pb、Mo 6种重金属都有不同程度的积累,其中Cd、Cu、As 3种重金属的积累程度最为严重;Cr、Ni、Mn含量低于土壤背景值,属清洁元素。修复后,各重金属含量均有所降低,土壤综合污染指数P综<3,土壤的综合潜在生态危害性大大降低,土壤为中度污染,但Cd仍具有很强的潜在生态风险,As存在中度潜在生态风险,Cu存在轻度潜在生态风险。更多还原     

拓扑半金属及磁性拓扑材料的单晶生长

拓扑材料因具有新奇物理特性受到广泛关注,这些材料一方面为基础物理研究提供了新的平台,另一方面在以拓扑物理为基础发展的器件研究方向上展现出潜在应用价值.凝聚态领域对于拓扑材料相关物理问题的研究主要通过两种方式开展:一是在已知的拓扑材料中不断挖掘新的实验现象和物理问题;二是不断预言和探索发现新型拓扑材料体系并开展合成.无论哪种方式,高质量单晶的获得都至关重要,它为角分辨光电子能谱、扫描隧道显微谱和磁场下的量子振荡等实验研究提供了前提保障.本文总结了拓扑材料的分类和发展,基于本研究组近些年开展的工作介绍了助溶剂法、气相输运法这两种拓扑材料单晶生长中常用的方法,并详细介绍了拓扑物性研究领域几类典型的拓扑材料及其生长方法,如拓扑绝缘体/拓扑半金属、高陈数手性拓扑半金属和磁性拓扑材料等.     

Tip-induced superconductivity commonly existing in the family of transition-metal dipnictides MPn_2

We report the tip-induced superconductivity on the topological semimetal NbSb₂, similar to the observation on TaAs₂ and NbAs₂. Belonging to the same family of MPn₂, all these materials possess similar band structures, indicating that the tip-induced superconductivity may be closely related to their topological nature and share a common mechanism. Further analysis suggests that a bulk band should play the dominant role in such local superconductivity most likely through interface coupling. In addition, the compatibility between the induced superconductivity and tips’ ferromagnetism gives an evidence for its unconventional nature. These results provide further clues to elucidate the mechanism of the tip-induced superconductivity observed in topological materials.     

TCLP法评估贵溪冶炼厂附近土壤重金属生态环境风险

贵溪冶炼厂附近农田长期受到该厂重金属废水的污灌,导致土壤受到严重污染,相关土壤修复措施已开展多年。为了解该地区土壤重金属污染状况及植物修复效果,采集了该厂附近3种典型重金属污染土壤:未受修复土壤(A)、正在进行修复土壤(B)及已受植物修复的土壤(C),TCLP法研究了土壤表层(0~20cm)中4种主要重金属(Cu、Pb、Cd、Zn)有效态重金属含量,并对其生态风险进行评估。结果显示,植物修复前土壤中重金属总量和有效态含量显著高于修复后土壤的含量;植物修复对4种重金属有效态及总量去除效果明显,去除率分别达Cu64.83%、61.35%;Cd 53.6%、46.67%;Zn 22.51%、8.88%和Pb 7.76%、4.84%;内梅罗综合指数法评价指出,修复前土壤处于重度污染,修复后土壤污染状况明显减轻,但依然处于中度污染,土壤中重金属Cu和Cd具有较强的生态风险,其主要原因为大气沉降所导致。更多还原     

超高性能水泥基复合材料抗多次侵彻性能研究

采用普通混凝土成形工艺和热水养护制度,制备出了抗压强度120~250 MPa的超高性能水泥基 复合材料。在获得优异静态力学性能的基础上,进行了超高性能水泥基复合材料抗多次侵彻研究,分析了侵 彻过程中的靶体破坏形态。根据获得的侵彻深度数据,在J.T.Gomez等提出的多次侵彻模型基础上,修正了 与靶体抗压强度有关的多次侵彻深度计算经验方程。     

Phase field simulation of single bubble behavior under an electric field

Based on the Cahn-Hilliard phase field model, a three-dimensional multiple-field coupling model for simulating the motion characteristics of a rising bubble in a liquid is established in a gas-liquid two-phase flow. The gas-liquid interface motion is simulated by using a phase-field method, and the effect of the electric field intensity on bubble dynamics is studied without electric field, or with vertical electric field or horizontal electric field. Through the coupling effect of electric field and flow field, the deformation of a single rising bubble and the formation of wake vortices under the action of gravity and electric field force are studied in detail. The correctness of the results is verified by mass conservation, and the influences of different electric field directions and different voltages on the movement of bubbles in liquid are considered. The results show that the ratio of the length to axis is proportional to the strength of the electric field when the air bubble is stretched into an ellipsoid along the electric field line under the action of electrostatic gravity and surface tension. In addition, the bubble rising speed is affected by the electric field, the vertical electric field accelerates the bubble rise, and the horizontal direction slows it down.     

Electronic Structure of the Weak Topological Insulator Candidate Zintl Ba3Cd2Sb4

One of the greatest triumph of condensed matter physics in the past ten years is the classification of materials by the principle of topology.The existence of topological protected dissipationless surface state makes topological insulators great potential for applications and hotly studied.However,compared with the prosperity of strong topological insulators,theoretical predicted candidate materials and experimental confirmation of weak topological insulators(WTIs) are both extremely rare.By com...