氟化梯度折射率塑料光纤带宽特性计算

基于氟化聚合物梯度折射率圆对称塑料光纤(PF-GIPOF)的传输参量计算,分析其传输特性,推导出频域基带功率传输函数,得到一种参数完整的色散计算模型.理论分析了光源特性、模式时延和模式损耗对带宽的影响并对色散进行拟合和计算.在波长和激光斑半径相异的光源激励下,对不同长度、不同折射率指数的PF-GIPOF的频率响应进行仿真验证.理论计算和实验结果表明,200 m长的PF-GIPOF在1 300 nm工作波长下,半径11.76μm的激光斑激励出的传导模最少,由于差分模式损耗作用,系统带宽提升了3.56 GHz,在α=2.16的折射率下可以得到最大的带宽优化.该计算模型可有效地用于PF-GIPOF通信系统的参量选取和带宽预测.     

高温季节碾压混凝土坝强约束区温控防裂方案研究

我国西南地区高温季节持续较长,碾压混凝土坝面临施工期温度裂缝的威胁．基于碾压混凝土坝施工期开裂机理,结合某大型碾压混凝土重力坝强约束区高温季节的施工,采用有限元仿真算法模拟了不同昼夜温差条件下的混凝土温度场和应力场发展过程,根据计算结果对表面保温和水管冷却过程中的具体参数进行优化,成果对同类工程具有参考价值．     

Hotspots of the sensitivity of the land surface hydrological cycle to climate change

Due to the shortage of the global observational data of the terrestrial hydrological variables,the understanding of how surface hydrological processes respond to climate change is still limited.In this study,the Community Land Model(CLM4.0)with high resolution atmospheric forcing data is selected to simulate the global surface hydrological quantities during the period 1948–2006and to investigate the spatial features of these quantities in response to climate change at the regional scales.The sensitivities of evaporation and runoff with respect to the dominant climate change factors(e.g.temperature and precipitation)derived from the concept of climate elasticity are introduced.Results show that evaporation has a declining trend with a rate of 0.7 mm per decade,while runoff shows a weak increasing trend of 0.15 mm per decade over the global land surface.Analyses of the hotspots in the hydrological cycle indicate that the spatial distributions for evaporation and runoff are similar over many areas in central Asia,Australia,and southern South America,but differ largely in high latitudes.It is also found that,the evaporation hotspots in arid regions are mainly associated with the changes in precipitation.Our sensitive analysis suggests that the hydrological quantities show a rather complicated spatial dependency of response of the water cycle to the different climate factors(temperature and precipitation).     

ATHK1 acts downstream of hydrogen peroxide to mediate ABA signaling through regulation of calcium channel activity in Arabidopsis guard cells

Plants gradually develop their ability to tolerate environmental water deficit as part of the evolutionary process.Abscisic acid(ABA) plays a critical role during drought and osmotic stress.Several histidine protein kinases are regarded as osmotic sensors or regulators in the adaptive response of plants to water deficit.In this study,we report that ATHK1,which was previously shown to function as an osmotic regulator,is involved in ABA-induced stomatal signaling in Arabidopsis.Mutants null for ATHK1 expression were unable to transmit normal ABA responses in guard cells,including inducing stomatal closure,producing hydrogen peroxide and activating calcium influx.Moreover,patch clamp and confocal analysis demonstrated that ATHK1 may function downstream of hydrogen peroxide in ABA-induced stomatal closure,by regulating calcium channel activity and calcium oscillation in Arabidopsis guard cells.     

Cu/TiO2光催化还原硝酸根

以TiCl3为原料,通过喷雾干燥法一步合成锐钛矿Cu/TiO2,并用于紫外光下还原硝酸根.利用XRD,SEM,TEM,紫外可见漫反射等研究样品的性质.该方法合成的锐钛矿Cu/TiO2,铜以Cu＋的形式存在.制备的2％ Cu/TiO2催化剂活性最佳,反应240 min后,硝酸盐转化率为31％,氮气的选择性为56％.     

临汾段汾河水环境质量评价

运用主成分分析法对临汾段汾河水质的分析结果显示,临汾段汾河在1993年至2008年的16年间水质呈不断下降的趋势:四项指标中BOD5增加了2.417,COD增加了2.379,DO增加了2.703,NH3N增加了1.108,从一定程度上反映了临汾段汾河的污染程度在不断加重;临汾段汾河水质下降的主要原因是沿岸市县经济迅速发展,工业化指数增高,城市生活污水排放量增大所致.     

PVC保鲜膜在食品模拟液中邻苯二甲酸酯和己二酸酯的定量分析及迁移规律研究

文章采用气相色谱-质谱分析法（GC-MS）对PVC食品保鲜膜在四种食品模拟浸泡液中邻苯二甲酸酯和己二酸酯的含量及其迁移规律进行研究.结果表明,除水性食品模拟液外,邻苯二甲酸酯和己二酸酯较易迁移至食品模拟液中,且随着迁移时间的增加,邻苯二甲酸酯和己二酸酯的迁移量逐渐增加并趋于平衡,说明长期使用PVC保鲜膜存在安全隐患.     

尿素-双醛淀粉用作纺织浆料的可行性研究

介绍了尿素-双醛淀粉的制备工艺并测试了该产品的粘度、粘度热稳定性、粘附力,与玉米淀粉进行浆液性能对比,粘度热稳定性提高了6.7%,纯棉和涤棉粗纱的断裂伸长率分别提高6.9%和3.6%,结果表明尿素-双醛淀粉浆液性能优良,用作浆料来进行经纱上浆完全适宜;将尿素-双醛淀粉与变性淀粉JFJ以1∶1.98的比例混合后进行浆纱测试,测试结果与现今纺织厂常用的浆料配方相比,浆纱断裂强力、浆纱伸长率、上浆率、增强率和浆纱耐磨次数都基本相近,纱线毛羽降低率、减伸率更为优异,分别提高10.7%、4.8%,浆纱质量明显提高。     

大各向异性锑锰改性PbTiO3压电陶瓷制备工艺研究

实验研究了以（Ｍｎ１／３Ｓｂ２／３）＾４＋Ｂ位取代Ｔｉ＾４＋为特征的大各向异性改性ＰｂＴｉＯ３压电陶瓷制备工艺,通过详细研究工艺条件对改性ＰｂＴｉＯ３陶瓷性能的影响。确定了其较佳工艺参数,在优化的工艺条件下,该陶瓷具有高压电活性,大压电各向异性,小介电常数,低机械品质因素,在多种压电超声换能器的研制方面显出良好应用前景。     

康复新液对2,4-二硝基氯苯联合醋酸诱导大鼠溃疡性结肠炎的影响

目的:探讨中药康复新液经灌肠给药对2,4-二硝基氯苯联合醋酸诱导大鼠结肠炎的治疗作用。方法:采用灌肠给药方式对溃疡性结肠炎(UC)模型大鼠进行治疗,通过测定大鼠DAI指数、脏器指数,检测血清IL-4、IL-10的表达水平,观察结肠黏膜损伤程度及病理改变来评价康复新液对大鼠UC的影响。结果:阳性药美沙拉嗪及治疗药物康复新液均能改善UC大鼠结肠组织的病变程度,修复肠道受损黏膜,病理组织学评分明显下降并具有统计学意义(P<0.01或P<0.05),提示灌肠有明显的治疗效果;康复新液高、中、低剂量组均能不同程度的降低DAI评分、结肠指数,缓解黏膜水肿,提高IL-4(P<0.01)、IL-10(P<0.01)的表达水平。从黏膜损伤及病理组织学评分可见康复新液组促进溃疡面愈合的效果更优。结论:康复新液对DNCB联合醋酸诱导的UC大鼠有治疗作用,可有效促进UC大鼠结肠溃疡的愈合,能有效的减轻UC大鼠的腹泻症状(DAI评分降低)。