An enhanced,acoustic emission-based,single-fiber-composite test

In the single-fiber-composite (SFC) test, a fiber imbedded in a matrix is loaded in tension, resulting in a fragmentation of the fiber. In the conventional version of this test, the final fiber fragmentation length distribution is used with a micro-mechanical model to determine the average fiber/matrix interfacial shear stress. In the enhanced version of this test, one also determines the applied stress at each fiber fracture, and from this, one can evaluate the strength of the fiber at short gage lengths. In our measurement system, we utilize an acoustic emission (AE) technique to detect the fiber fractures and to locate the fiber breaks and so determine both the fiber failure stresses as well as the fiber fragmentation lengths while the test is in progress. Critical to the success of this test is a broadband AE system that utilizes point-like AE sensors, procedures for evaluatingin situ, the wavespeed of the first wave arrival and signal processing techniques for determining the arrival time of this signal as precisely as possible for a broad range of wave shapes. Here we describe the application of such an enhanced SFC test procedure to investigate the failure of a Nicalon fiber in an epoxy matrix.     

使用Dreamweaver结合ASP技术构建企业科技与节能管理系统

节能减排和科技创新是我国保持可持续发展的重要保障,国家高度重视这两项工作,十一五以来陆续出台了鼓励节能减排和科技创新的相关鼓励政策。节能与科技管理系统是企业展示自身节能减排和科技创新成果和经验的窗口,在节能减排和科技创新工作中发挥着重要作用。本文介绍了作者利用Dreamweaver和ASP技术构建企业节能与科技管理系统的一些认识和经验。     

Evaluation of the Effects of Developmental Trauma on Neurotransmitter Systems Using Functional Molecular Imaging

Early life stress (ELS) is strongly associated with psychiatric disorders such as anxiety, depression, and schizophrenia in adulthood. To date, biological, behavioral, and structural aspects of ELS have been studied extensively, but their functional effects remain unclear. Here, we examined NeuroPET studies of dopaminergic, glutamatergic, and serotonergic systems in ELS animal models. Maternal separation and restraint stress were used to generate single or complex developmental trauma. Body weights of animals exposed to single trauma were similar to those of control animals; however, animals exposed to complex trauma exhibited loss of body weight when compared to controls. In behavioral tests, the complex developmental trauma group exhibited a decrease in time spent in the open arm of the elevated plus-maze and an increase in immobility time in the forced swim test when compared to control animals. In NeuroPET studies, the complex trauma group displayed a reduction in brain uptake values when compared to single trauma and control groups. Of neurotransmitter systems analyzed, the rate of decrease in brain uptake was the highest in the serotonergic group. Collectively, our results indicate that developmental trauma events induce behavioral deficits, including anxiety- and depressive-like phenotypes and dysfunction in neurotransmitter systems.     

大气生物气溶胶的源排放与源解析研究进展

2019年新冠肺炎(COVID-19)的全球爆发引起了公众对生物气溶胶的广泛关注。生物气溶胶是大气气溶胶的重要组成部分。生物气溶胶由于具有普通气溶胶的理化性质和本身特有的生物学特性,在全球生态系统、气候变化、空气质量和公共卫生等领域均扮演十分重要的角色。然而,目前学术界对生物气溶胶的研究主要集中在采样监测、消杀防护以及其环境与健康效应等方面,关于源特性研究相对滞后。基于此,聚焦大气中微生物的来源现状,综述了最近20年来生物气溶胶的自然源和人为源排放特性研究进展,并阐述了影响源排放和输送过程的主要因素(如生物地理区域、土地利用类型和环境因素等),探讨了当前生物气溶胶的各种源解析方法。最后,给出了生物气溶胶来源下一步的研究展望,以期为深入理解生物气溶胶的来源、输送与变化机理,更好地评估大气微生物污染水平与监控病原体的气溶胶传播提供参考。     

阳极溶解促进位错发射和运动的TEM原位观察

用自制的恒位移加载台在ＴＥＭ中原位观察了３１０不锈钢在水中阳极溶解前后加载裂尖前方位错形貌的变化．在排除室温蠕变影响后发现，阳极溶解能明显促进位错发射、增殖和运动．３１０不锈钢薄膜试样在室温水中能产生应力腐蚀．     

声发射源定位不确定度的计算

针对声发射检测中的声发射源定位的不确定性问题，就其影响因素，在常用的16MnR钢制板件上进行了检测实验，并开展了实验数据的计算、分析与讨论。     

Luminescent Amphiphilic Aminoglycoside Probes to Study Transfection

We report the characterization of amphiphilic aminoglycoside conjugates containing luminophores with aggregation-induced emission properties as transfection reagents. These inherently luminescent transfection vectors are capable of binding plasmid DNA through electrostatic interactions; this binding results in an emission “on” signal due to restriction of intramolecular motion of the luminophore core. The luminescent cationic amphiphiles effectively transferred plasmid DNA into mammalian cells (HeLa, HEK 293T), as proven by expression of a red fluorescent protein marker. The morphologies of the aggregates were investigated by microscopy as well as ζ-potential and dynamic light-scattering measurements. The transfection efficiencies using luminescent cationic amphiphiles were similar to that of the gold-standard transfection reagent Lipofectamine® 2000.     

静磁场对ZK60镁合金组织的影响

试验发现在镁合金的凝固过程中施加静态磁场能有效细化晶粒，减小晶界化合物的厚度，同时，出现了大量细小块状化合物，这有利于提高镁合金的成形性能。     

高温熔融-电感耦合等离子体原子发射光谱法测定含铁尘泥中5种有害元素

准确、快速地测定含铁尘泥中有害元素,对含铁尘泥节能降废项目研究及综合利用有着重要的指导意义。实验针对含铁尘泥试样因含碳量高,导致常规酸溶解方法如果不增加除碳步骤则很难完全分解试样的问题,采用高温熔融法将试样制成熔融液后倾倒于稀酸中溶解的方法,解决了碳含量高难溶解的问题。采用四硼酸锂-碳酸锂混合熔剂在高温下将试样熔融,熔融液高温倾倒于稀酸中制成澄清溶液,由于骤冷,试样炸裂成微小玻璃珠,无迸溅,操作简单,使得后续溶解过程快速完成,从而建立了电感耦合等离子体原子发射光谱(ICP-AES)测定P、Pb、K、Na、Zn共5种有害元素的方法。按照实验方法测定含铁尘泥中P、Pb、K、Na、Zn,测定值的相对标准偏差(RSD,n=9)在1.4%～5.7%之间,加标回收率在96%～110%之间。研究结果表明方法能够满足含铁尘泥样品中5种元素的定量分析要求。     

Passivation of Fe-Cr alloys studied with ICP-AES and EQCM

The response of sputter deposited Fe-15Cr and Fe-25Cr alloys to a rapid potential increase in the passive region was studied using two in situ methods: electrochemical quartz crystal microbalance and inductive coupled plasma-atomic emission spectroscopy (ICP-AES). Both methods indicated an increase in the dissolution rate of iron following the potential change; the total amount of material dissolved being higher for the Fe-15Cr alloy. For both alloys, about 10% of the total dissolved material was Cr. This result compared well with experiments on a 430 stainless steel. ICP-AES is shown to be useful for the in situ determination of partial currents of metal dissolution using solution analysis in a flow cell.