高强硼钢热拉伸性能试验研究

运用G1eeb1e1500D热模拟试验机对柱状硼铜（USIBOR1500P）进行热拉伸试验,研究高温下热成形硼钢的变形抗力。首先将试件加热到奥氏体化温度,再以40℃／s冷却速率降到950～550℃,分别以应变速率为0．01、0．1、1／s进行热拉伸试验,获得应力一应变曲线。通过实验结果,分析成形温度、变形程度和应变速率对高温成形件的影响,并利用最小二乘法进行多元线性回归,建立高温下的本构模型。试验结果表明：成形温度和应变速率对变形抗力的影响较为敏感,变形抗力随着成形温度的升高而减小,变形抗力随着变形程度、应变速率的增加而增大。     

高钼奥氏体不锈钢高温软化行为与流变应力模型

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亚硒酸钠对高温胁迫下梨苗部分酶活性的影响

用1．0mg．L~(-1)亚硒酸钠预先处理梨叶片,4d后用高温胁迫,5h后开始测定各种指标．结果表明,经亚硒酸钠处理的梨叶片愈创木酚过氧化物酶(GPX)、谷胱甘肽还原酶(GR)和过氧化物酶(POD)活性提高,脂氧合酶(LOX)活性下降．     

基于平均皮肤温度的个体热舒适评价模型

在环境温度为21,24,26,29℃的条件下测量了22个受试者的局部皮肤温度,并基于10个皮肤温度测试点对受试者的平均皮肤温度进行了计算.然后,对受试者的热舒适程度和热感觉进行了问卷调查.采用马氏距离判别法建立了基于平均皮肤温度的个体热舒适评价模型.实验结果表明,受试者在热舒适与热不舒适时的平均皮肤温度有显著差异.根据评价模型可知：人体感到热舒适时的平均皮肤温度范围为32.6～33.7℃;该模型对72%的受试者的热舒适程度进行了正确判断;考虑性别差异对平均皮肤温度和热舒适程度的影响有助于提高模型的精确度.因此,平均皮肤温度可作为一个有效评价稳态热环境下个体热舒适的生理指标.     

活性炭/二氧化锰复合材料的制备及性能研究

采用水热法,以果壳活性炭为载体,制备活性炭（AC）/二氧化锰（MnO2）纳米线复合材料。采用X射线衍射仪（XRD）、场发射扫描电子显微镜（SEM）、比表面及孔径分析仪、同步热分析仪（TG）以及紫外可见吸收光谱（UV/Vis）对所得材料的组成、形貌和结构进行表征,并对其光催化性能进行研究。结果表明:采用水热法可实现活性炭与MnO2的有效复合。在复合材料中,MnO2纳米线多以无定形态的形式存在且尺寸均一,将活性炭有效胶结在一起,从而使得活性炭比表面积和孔隙率降低,但其孔径大小保持不变。光催化实验结果表明,AC/MnO2复合材料对于有机染料具有明显、高效的降解效果,对亚甲基蓝的降解主要是吸附和光催化两者协同效应的结果。该结果拓展了活性炭在光催化领域的应用。     

Electrochemical behavior of insulin on pretreated carbon black electrode enhanced with silicon carbide nanostructure

We previously reported the direct electrochemical detection of insulin at bare carbon electrodes. Here a novel modified acetylene carbon black paste electrode(SiC/CB-CPE), based on the outstanding characteristics of silicon carbide nanostructure,was developed for the electrooxidation of insulin in alkaline solution and it was characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) in 5 mmol/L Fe(CN)63-/4- solution. It is found that silicon carbide nanostructure doped into the CB-CPE greatly facilitates the redox electrochemistry of Fe(CN)63-/4- probe and the electrochemical oxidation of insulin. The electrooxidation of insulin is a one-electron and one-proton reaction and an irreversible adsorption-controlled electrode process. The anodic oxidation current increases linearly with the concentration of insulin from 1×10-7mol/L to1.2×10-6mol/L in 0.1 mol/L Na2CO3-NaHCO3 buffer solution(pH 10.0) and the detection limit was 50 nmol/L. In addition, the SiC/CB-CPE shows good sensitivity, reproducibility, renewability and capacity of resisting disturbance.     

Modeling of growth stress gradient effect on the oxidation rate at high temperature

A new oxidation kinetics model is established for high-temperature oxidation. We assume that the interface reaction is fast enough and the oxidation rate is controlled by diffusion process at high temperature. By introducing the growth stress gradient we modify the classical oxidation parabolic law. The modified factor of the oxidation rate constant is a function of growth strain, environment oxygen concentration, and temperature. The modeling results show that the stress gradient effect on the oxidation rate cannot be ignored. Growth strain will dominate whether the stress gradient effect promotes or slows down the oxidation process. The stress gradient effect becomes weaker at higher temperature. This effect is amplified at higher concentrations of environmental oxygen. Applied mechanical loads do not affect the oxidation rate. This model is available for high temperature oxidation of metals and alloys.     

Effect of al on behavior of AB5-type metal hydride anodes at elevated temperature

AB₅-type hydrogen storage alloys are the most promising materials used as the anode in commercial Ni-MH secondary battery. It is very important for electrode materials to have a wider operation temperature range. The component Al is the dominant element to control the electrochemical behavior of the AB₅-type alloys at elevated temperature. With the increase of the amount of Al the discharge capacity decreases and the retention of discharge capacity increases with increasing temperature. It is mainly due to the formation of stable and dense surface oxide film Al₂O₃, which inhibits the electrode corrosion and the further oxidation underneath the surface films.     

盐胁迫下野大豆无机离子分布的研究

用不同浓度的NaCl溶液处理野大豆幼苗后,测定并比较根及地上部的Na 、Cl-、K 含量.地上部及根部的Na 、Cl-含量随盐度的增加而升高,且累积趋势相似.盐胁迫下根部的Na 、Cl-含量明显高于地上部,说明盐生野大豆在盐胁迫下以根部优先积累盐离子为其适应特征.地上部及根部的K 含量随盐度的增加而降低.     

弯曲共振法测量金属材料高温弹性模量探讨

对弯曲共振法测量金属材料高温弹性模量的相关问题进行了探讨。结合铝合金高温弹性模量的测量,分析了弯曲共振法测量高温弹性模量中的各种影响因素对结果的影响;总结了弯曲共振法测量中的难点,列出了多种判别虚假共振峰的方法;采用频谱分析对动态法中判定共振频率的方法进行了改进并结合软件采用扫频技术将弹性模量测量自动化。成功应用于国产6061-T6系列铝合金高温弹性模量的测量。     

经高效熔体处理的易拉罐用铝材的高温流变应力行为

采用动态热模拟试验技术探讨了经高效熔体综合处理和均匀化退火后的易拉罐用铝材在高温压缩变形过程中，变形温度和应变速率对其稳态流变应力行为的影响规律。结果表明，该材料在高温变形时的稳态流变应力与应变速率、变形温度均满足Arrhenius方程，其中更满足双曲正弦函数关系；该材料的热变形是受热激活控制的塑性变形过程。     

The influence of test‐based accountability policies on early elementary teachers: School climate,environmental stress,and teacher stress

This study examined the potential influence of test‐based accountability policies on school environment and teacher stress among early elementary teachers. Structural equation modeling of data from 541 kindergarten through second grade teachers across three states found that use of student performance on high‐stakes tests to evaluate teachers indirectly was related to teachers’ professional investment via test stress in the environment. Although students in kindergarten through second grade do not take high‐stakes assessments, early elementary teachers reported high levels of stress associated with test‐based accountability policies. This study provides data across multiple states that test‐based accountability policies may have negative influences on school environment and teacher stress among early elementary teachers. Implications for practice and research are discussed.     

LD端面泵浦的Nd:YVO4晶体内部温度与热应力的理论表达式

推导了LD端面泵浦Nd：YVO4激光器的工作物质(Nd：YVO4晶体)内部的温度和热应力的理论表达式，为进一步消除高功率泵浦情况下Nd：YVO4晶体的热效应提供了新的理论依据。     

镉胁迫对水稻颖果充实和生理活性的影响

通过盆栽试验探讨Cd^2＋胁迫对扬稻6号和粳稻941颖果充实和生理活性的影响,结果表明：Cd^2＋胁迫降低颖果呼吸速率、光合速率以及ATP含量;降低颖壳和果皮叶绿素含量;使颖果灌浆速率减慢,鲜干重增加的速率减缓,灌浆的天数变短,最终成熟颖果干重降低。说明Cd^2＋胁迫降低颖果呼吸活性、能量物质以及其它生理活性,从而降低颖果的代谢活性和发育时间,最终导致贮藏物质的合成和积累量降低。     

硅对马铃薯试管苗根系生长及其细胞壁组成的影响

以马铃薯大西洋品种为材料,MS为基本培养基,研究硅对马铃薯组培苗根系生长及其细胞壁组成的影响。结果表明加硅后植株地上分枝数和生根数显著增加,根系粗壮而长,根系活力得到明显改善,根系细胞壁多糖中纤维素含量显著上升,而熬合剂提取果胶含量则显著下降。     

Characteristics of fluoride emission from five clay minerals as affected by temperature, heating time and addition of calcium compounds

Characteristics of fluoride emission from five clay minerals (montmorillonite, kaolinite, vermiculite, geothite, and allophane) as affected by temperature, heating time and addition of calcium compounds were studied. Marked increase of the fluoride emission rate was noticed with increase of temperature. The fluoride release, began at 500°C–600°C, and the main bulk of the fluoride emission occurred at the temperature of about 800°C. The loss of crystalline water was primarily responsible for the increase of fluoride emission. When minerals were heated at 800°C, The fluoride emission rate from the clay minerals reached the highest after heating for 1 hour. The samples treated by CaO, CaCO₃, Ca(OH)₂, Ca₃(PO₄)₂, and CaSO₄ had 55.45%, 59.58%, 46.45%, 54.31%, 31.25% reduction in the fluoride emission from montmorillonite at the temperature of 800°C, respectively. CaCO₃ had the highest fluoride fixing capacity compared to other calcium compounds. Project supported by the Special Funds for Major State Basic Research Project 973 (G1999011809) and Natural Science Foundation of Zhejiang Province.     

植物耐热生理生化指标研究进展

本文概述了高温逆境下植物体内与耐热性相关的一些生理生化指标的变化情况。     

环境温度对某深基坑围护结构内力与变形影响分析

从热传导的基本方程出发,介绍结构瞬态温度场和应力场有限元一般格式.编制东京新丰州变电所围护结构二维温度场有限元分析程序,采用ANSYS工程分析软件,计算该围护结构在环境温度变化过程中引起的温度场、温度应力及温度变形,同时计算了在开挖土压力作用下该围护结构的内力与变形,将两种变形与实测变形值进行比较.结果显示,环境温度变化对类似工程围护结构的内力与变形有不可忽视的影响,必须加以计算.     

城市行道树对一氧化碳和总悬浮颗粒物浓度的影响

选择福州几种主种的行道树为研究对象,分析车流量和环境因素与一氧化碳（CO）、总悬浮颗粒物（TSP）浓度的关系,揭示行道树在控制CO、TSP浓度中的贡献.结果发现车流量与道路中央CO浓度呈显著的指数关系,树下的环境弱化了这种关系,表明它们关系的改变主要是由于行道树的存在引起的,其改变的幅度可能还受到行道树的生理周期及林冠结构等因素的影响.除了在小叶榕试验点,车流量与TSP浓度均表现为显著的指数相关,且道路中央高于树下环境,表明车流量与TSP浓度关系的改变主要是由于行道树的存在,其改变的幅度可能还与道路宽度、所经车辆车速等因素有关.环境的温、湿度与CO浓度表现为弱相关.除了小叶榕树试验点,其它试验点环境温度均与TSP浓度表现为显著的正相关.无论有无行道树存在,环境湿度均与TSP浓度表现为较强的负相关.     

Effect of chloride content on bond behavior between FRP and concrete

For reinforced concrete structures located along the seaside, the penetration of chloride ions into concrete may be a threat to the durability of the structures. Experimental investigations were carried out to study the effect of chloride content on the bond behavior between concrete and fiber reinforced polymer (FRP) plates. Direct shear tests were conducted on the FRP strengthened concrete members. Before testing, the specimens were immersed in NaCl solutions with concentrations ranging from 3%—15% for different time (0—120 d). Then, the specimens were dried and tested to obtain the initial and ultimate debonding loads, together with strain distributions along the FRP plates of different load values. The correlations between chloride content and debonding parameters are established. Test results show that the debonding parameters are closely related to the immersing time rather than the chloride content of the solution.