Log-periodic quantum magneto-oscillations and discrete-scale invariance in topological material HfTe5

Discrete-scale invariance (DSI) is a phenomenon featuring intriguing log-periodicity that can be rarely observed in quantum systems. Here, we report the log-periodic quantum oscillations in the longitudinal magnetoresistivity (ρ_xx) and the Hall traces (ρ_yx) of HfTe₅ crystals, which reveal the DSI in the transport-coefficients matrix. The oscillations in ρ_xx and ρ_yx show the consistent logB-periodicity with a phase shift. The finding of the logB oscillations in the Hall resistance supports the physical mechanism as a general quantum effect originating from the resonant scattering. Combined with theoretical simulations, we further clarify the origin of the log-periodic oscillations and the DSI in the topological materials. This work evidences the universality of the DSI in the Dirac materials and provides indispensable information for a full understanding of this novel phenomenon.     

热电偶测温误差

热电偶在温度测量中产生测量误差的主要因素是热电偶插入深度、响应时间、热辐射及热阻抗。     

沿晶界疲劳开裂机理

采用扫描电镜电子通道衬度 (SEM ECC)技术 ,系统地研究了铜晶体中各种不同晶界的疲劳开裂行为 .直接的观察证据表明 :各种随机大角度晶界的疲劳开裂归因于驻留滑移带对晶界的撞击作用及随后的位错塞积 ;而当驻留滑移带能够连续穿过小角度晶界时 ,则不产生位错塞积和萌生沿晶界疲劳裂纹 .沿晶界疲劳开裂与否与驻留滑移带和晶界的交互作用方式密切相关 ,而与晶界结构本身无关 .     

Study of Association of Leptin and Insulin Resistance Markers in Patients of PCOS

Polycystic ovary syndrome (PCOS) is a common endocrinological disorder among women of the reproductive age group with long term sequelae which include diabetes mellitus, hypertension and CAD. The present study was conducted to evaluate the association of leptin—an adipokine playing an important role in carbohydrate metabolism and markers of insulin resistance among women with PCOS. Sixty diagnosed cases of PCOS as per Rotterdam criteria were enrolled in this study after informed written consent. Insulin resistance was estimated using the homeostatic model assessment-insulin resistance (HOMA-IR). HOMA-IR was calculated as the product of the fasting plasma insulin value (mU/ml) and the fasting plasma glucose value (mg/dl), divided by 405 and HOMA β was calculated as 360 × [insulin]/([glucose] − 63) % (glucose in mg/dl). Estimation of serum leptin levels was done by ELISA using leptin ELISA kit from (DRG). A positive correlation of serum leptin levels was observed with markers of insulin resistance. Multiple regression analysis with HOMA-IR as dependent variable demonstrated a statistically significant contribution of fasting insulin levels. This study highlights the role of leptin in alterations in carbohydrate metabolism in patients with PCOS.     

Teaching resistant novice educators to be critically reflective

Drawing upon our experience as university faculty in teaching novice educators, we explore the issue of resistance from students around learning that entails critical reflection. By novice educators, we refer to pre-service teacher candidates and graduate students in Education faculties, particularly graduate students in adult education/lifelong learning programs, who often do not have prior Education degrees or extensive experience as educators. We believe novice educators should be taught to be critically reflective, regardless of whether they teach in schools, government, the not-for-profit sector, or business sector.     

应用型本科人才培养改革的教师阻抗研究

当前,培养应用型本科人才的重要性已经得到上自国家政策层面下至地方本科院校的认可。然而,应用型本科人才的培养受到了教师阻抗的影响,减少或消除教师阻抗的对策是:派遣教师外出学习、建立良性运作机制等。     

单相流体阻力实验中压差测定对比研究

在化工原理实验单相流体阻力测定实验中,压差的测定方法一般有两种.实验对比研究结果表明在小流量条件下采用空气-水倒置U型管法较好,而在大流量条件下采用压力传感器-数字表系统测定较好.     

An Inorganic Magnesium-based Consolidant for the Consolidation of Silica Sand (A Substitute for Weathered Sandstone): A Preliminary Exploration

ABSTRACT

Sandstone is a common sedimentary rock that is easily carved due to its weakly cemented fine grains and relatively low strength. Therefore, numerous large-scale grottoes in China are made of sandstone. However, these sandstone cultural heritage structures are often seriously damaged due to temperature and humidity changes, air pollution, biodeterioration, and repeated dissolution and crystallization of soluble salts. In general, it is imperative that a consolidant capable of providing cohesion by infilling pores between the stone grains is synthesized. In recent years, it has been reported that using organic consolidation materials for sandstone protection comes with various negative effects, such as a short lifetime, poor compatibility, and preservation damage. Using inorganic consolidation materials to protect sandstone seems to be one of the research trends for the future. Herein, this paper introduces a permeable, inorganic magnesium-based material (MMH solution) for silica sand consolidation. To assess this consolidant, the paper investigates the influence of varying molar ratios of MgO:MgCl₂·6H₂O:H₂O on properties such as penetration depth, consolidation weight, colour variation, and compressive strength. The results demonstrate that the molar ratios of MgO:MgCl₂·6H₂O:H₂O can significantly affect the consolidation performance. Additionally, it is believed that the MMH solution of MgO:MgCl₂·6H₂O:H₂O?=?5:1:16 can be successfully used for the consolidation of silica sand, as the cubic specimens’ surface micrographs show good compatibility between the consolidation product and sand grains. Experiments (i.e. weight loss rate and mineralogical compositions analysis) are performed to evaluate the cubic specimens’ water resistance properties after being immersed in water. Furthermore, the consolidation material’s failure mechanism as a self-sacrificing material is preliminarily analyzed. Results indicate that MMH solution is a promising conservation material that shows great potential for consolidating severely weathered sandstone.     

构造复势函数求解含裂纹载流薄板电流密度分布

构造出一种适用于求解带有圆形孔洞的载流薄板电流密度分布的势函数，利用这种势函数以及保角映射方法，求解了带有裂纹的载流薄板的电流密度分布。计算结果显示裂纹尖端附近有很强的电流集中现象，从而为研究裂纹尖端电热效应提供了一种简单有效的新方法。     

含竖直裂纹弹性材料与梯度材料粘接的接触问题

从功能梯度材料的弹性理论出发,首先推导出梯度材料在不同边界条件下的状态方程,进而使用Fourier变换技术将含裂纹弹性材料与梯度材料粘接的接触问题转化为边值问题,建立起该数学模型。构造带技巧性的积分变换方法将混合边值问题化为奇异积分方程,并利用Gauss—Chebyshev积分公式将奇异积分方程离散为计算机可实现的代数方程组,编制计算机程序并上机调试,得出数值模拟结果。