κ-卡拉胶烷氧基化衍生物的制备及其抗氧化活性

在温和条件下将κ-卡拉胶(KC)降解成低分子量κ-卡拉胶(LMW-KC),然后与长脂链溴代烷在二甲基亚砜(DMSO)中进行烷氧基化,合成具有长脂链的LMW-KC烷氧基化衍生物.IR、~(13)C-NMR和~1H-NMR测试结果表明,κ-卡拉胶降解后其结构单元没有被破坏.抗氧化活性的测定结果表明,LMW-KC的烷氧基化衍生物抗氧化活性明显增强.     

A comparison study on the melt crystallization kinetics of long chain branched and linear isotactic polypropylenes

The isothermal and non-isothermal crystallization kinetics of LCBPP and linear-iPP was investigated by optical microscopy and differential scanning calorimetry （DSC）. The optical microscopy results in the isothermal crystallization process show that the crystals of LCBPP grow slower than the crystals of the linear-iPP. This originates from the low chain mobility, or in other words, the lower chain diffusion rate of LCBPP due to the existence of long side chains. The DSC results in the isothermal crystallization process show that the LCBPP exhibits, however, a higher overall crystallization rate with respect to the linear-iPP. This is related to the higher nucleation ability of LCBPP since the isothermal crystallization process of both LCBPP and linear-iPP are nucleation-dominated. Avrami analysis indicates that the nucleation nature and crystal growth manner of LCBPP and linear-iPP are about the same. The analyses of the non-isothermal crystallization processes indicate an increment in crystallization rate with increasing cooling rate. But at any cooling rate, the linear-iPP crystallizes more quickly than the LCBPP. This implies that the non-isothermal crystallization processes of LCBPP and linear-iPP are diffusion-dominated, in which the lower chain diffusion rate of LCBPP results in the slower crystallization of it.     

Differential gene expression profile in ischemic myocardium of Wistar rats with acute myocardial infarction

To determine the differential genes in ischemic myocardium of Wistar rats with acute myocardial infarction （AMI）, we constructed two differential gene expression profiles. AMI model was generated by Iigation of the left anterior descending coronary artery in Wistar rats. Total RNA was extracted from the normal and the ischemic heart tissues under the IigaUon point at the 8th day after the operation. Differential gene expression profiles of the two samples were constructed by using long serial analysis of gene expression （LongSAGE）. Real time fluorescence quantitative PCR （Q-PCR） was used to confirm the expression changes of partial target genes. The main results were as follows： a total of 15966 tags were screened from the normal and the ischemic LongSAGE maps, and 9646 tags in the normal tissue and 9563 tags in the ischemic tissue were obtained. Among them, 7665 novel tags were identified by NCBI BLAST search. In the ischemic tissue, 142 genes significantly changed compared to those in the normal tissue （P〈0.05）. These differentially expressed genes may play important roles in the pathways of oxidation and phosphorylation, ATP synthesis and glycolysis and so on. Partial genes identified by the LongSAGE were confirmed by Q-PCR. The results show that AMI causes a series of gene expression changes in the regulation of the pathways related to energy metabolism.     

硬聚氯乙烯三通管挤胀成型的有限元模拟及优化

采用Ansys^®通用分析软件对硬聚氯乙烯(UPVC)三通管的挤胀成型过程进行了有限元模拟和优化。通过模拟获得了三通管挤胀成型过程中的主要失效形式。采用单步循环法模拟了不同过渡圆角情况下三通管的成型过程,确定了合理的设计域,在此基础上分别采用子问题逼近法和一阶优化法获得了对于不同过渡圆角情况下三通管优化的设计参数组合。在模拟和优化的基础上,利用自行设计的实验台成功地实现了UPVC三通管的挤胀成型。实验和模拟研究结果表明,挤胀成型方法对于一些特定类型制品的成型是可行的。     

水上平台钢管桩施工技术

本文在详细介绍佛山市华阳桥水上平台钢管桩的施工技术,在钢管桩特点的基础上,提出了钢管桩垂直承载力的计算方法,并详细介绍了钢管桩承载力计算,最后提出了钢管桩施工中应注意的问题以供工程施工参考。     

直缝焊管排辊成形中预成形段的动力显式仿真

考虑到直缝焊管的排辊成形过程非常复杂,其间涉及明显的非线性,为了更好地了解板带的成形规律,针对406 mm焊管排辊成形机组的预成形段建立了弹塑性大变形有限元模型,采用动力显式算法进行了仿真计算,分别得到了预成形段管坯的等效塑性应变分布和几何变形,并通过开口度和板宽的测量验证了仿真的准确性.研究结果表明:在预成形段时最大塑性变形发生在带钢的边缘,其次是带钢中心以及带钢与粗成形轧辊端面接触的区域;弯边轧辊对带钢边缘的变形贡献最大.     

黄色到红色长余辉材料Y2O2S的制备和光谱性能研究

采用高温固相法合成了Eu~(3 )含量不同的Y_2O_2S长余辉材料,实验发现Eu~(3 )含量为0%、5%、10%、15%时样品分别呈现黄色、桔黄色、红色、深红色.采用X射线衍射(XRD)、扫描电镜(SEM)、荧光光谱(PL)对样品进行了表征.     

引进型300 MW机组凝汽器改造

针对湖北汉川电厂引进型300 MW汽轮机组凝汽器存在的真空严密性差、清洁度低等问题,通过分析原因,提出管系置换的改造方案。采用新型BD模块式排管,合理调整管板间距,并采用铜管和不锈钢管的冷却管混合方案对旧凝汽器进行改造。改造后在汽轮机功率不变的条件下,凝汽器背压降低2.4-3.2kPa,传热系数提高0.3-0.8kW/（m^2·℃）,运行良好。     

基于CDMA2000移动目标的探测方法研究

针对目前车载式移动目标探测系统复杂、受环境影响较大、灵活性差等缺点,提出了一种基于CDMA2000移动目标的手持式设备探测的实现方案,介绍了手持式探测设备的各个模块功能,给出了整个系统工作原理及流程,重点描述了手持式设备探测的实现方案,最后又提出了进一步的实施措施。     

助熔剂H_3BO_3对绿色荧光粉SrAl_2O_4∶Eu~(2+)发光性能影响研究

以H3BO3为助熔剂,在1200℃、H2还原气氛下成功制备出绿色荧光粉SrAl2O4∶Eu2+,并研究了不同H3BO3含量对SrAl2O4∶Eu2+发光性能和余辉特性的影响,结果表明随着H3BO3含量的增加,样品的发射光谱发生了"蓝移"现象,并随B3+的掺入,Sr0.96Al2O4∶0.04Eu2+呈现出了长余辉特性,同时增强了样品的发光强度和余辉时间,最佳的H3BO3含量为15%,其余辉时间可以达到6h.