丙烯酸酯/SBS共聚物的合成及性能研究

在SBS上引入极性基团进行原位改性,可以提高与极性材料的相容性及粘接性能.以120号溶剂油和甲苯为混合溶剂,以MMA、BA和MA为单体对SBS进行共聚改性.研究了反应条件、原料配比、用量以及混合溶剂的配比对产物性能的影响.用IR、GPC等对产物进行了表征.研究结果表明,其最佳配比为:m(BA):m(MMA)=1:1.2;m(BA):m(MMA):m(SBS)=9:10.8:50;m(甲苯):m(120号溶剂油):1:3;引发剂BPO的用量为0.9～1.2g/100g单体;反应温度为80～83℃;反应时间为7.5～8h.所得到的丙烯酸酯/SBS共聚物有着良好的粘接性能及储存稳定性.比未改性的SBS有着更广泛的应用范围.     

对甲基苯胺改性双氰胺环氧固化剂的合成及性能

用对甲基苯胺对双氰胺进行改性,制备了一种新型的改性双氰胺固化剂,对合成条件进行了优化,并对其固化环氧树脂条件进行了研究。结果表明,对甲基苯胺改性双氰胺的较佳工艺条件为对甲苯胺和水的物质的量比定为1∶1.5,双氰胺和苯胺的物质的量比为1∶1,转速为一档,于90℃,反应3h,收率85%。通过测试涂层硬度来考察固化工艺与性能。作为环氧树脂固化剂单独使用时,固化温度为110℃,比双氰胺体系固化温度160℃降低了近50℃,对甲基苯胺改性双氰胺固化温度高于120℃时,涂膜硬度大于双氰胺固化温度为160℃时涂膜硬度。     

基于Copula函数的多变量水文不确定性处理器

传统的水文不确定性处理器(HUP)属于单变量结构类型,只能独立地给出各预见期实际流量的贝叶斯后验概率密度,没有考虑它们之间的内在相关性。本文利用Copula函数推导了贝叶斯转移预报(BTF)方法中后验转移密度的解析表达式,提出了基于Copula函数的贝叶斯转移预报(CBTF)方法和基于Copula函数的多变量水文不确定性处理器(CMHUP),进而发展了基于Copula函数的贝叶斯极值预报(CBEF)方法,并应用于三峡水库入库洪水预报中。结果表明:所提方法实用有效,CBTF方法和CMHUP可以定量地评估三峡水库入库流量转移预报的不确定性,准确揭示了水文预报不确定性在时间上的演变特征,CBEF方法则提供了预见期时段内最大入库流量预报的不确定性信息。所提方法不需要进行线性-正态假设,能够很好地捕捉流量过程的非线性和非正态特征,适用范围更加广泛,对于支撑防洪减灾和水库运行调度具有重要的参考价值。     

基于海温多极指标的长期降水预报方法

准确的长期定量降水预报对水库防洪兴利综合调度具有重要的理论价值和现实意义。本文提出基于海温多极指标的长期定量降水预报方法,并以长江上游区间为例进行应用和检验。结果表明:海温多极指标能有效预报长江上游1961—2017年汛期(5—10月)的月降水量。相比于传统的单元、多元线性回归和典型相关分析方法,该方法更为稳健、预报精度较高,特别在初汛及后汛期月降水量预报上,具有显著的优越性。研究成果可以为三峡水库防洪兴利调度决策提供科技支撑。     

Relationship between solid fraction and distribution of Pb in Al-Pb ingot

ＩＮＴＲＯＤＵＣＴＩＯＮＡｌ Ｐｂｈｙｐｅｒｍｏｎｏｔｅｃｔｉｃａｌｌｏｙｉｓａｎｅｗｔｙｐｅｂｅａｒ ｉｎｇｍａｔｅｒｉａｌ[1] .Ｇｒｅａｔｅｍｐｈａｓｉｓｈａｓｂｅｅｎｐｕｔｏｎｉｔｅｓ ｐｅｃｉａｌｌｙｓｉｎｃｅ 1990ｓ[2～ 4 ] .ＰｂｈａｓｅｘｃｅｌｌｅｎｔｌｕｂｒｉｃａｔｉｎｇｐｒｏｐｅｒｔｙｗｈｉｃｈｃａｎｍａｔｃｈｔｈａｔｏｆＳｎ ,ｂｕｔｉｔｓｃｏｓｔｉｓｍｕｃｈｌｏｗｅｒｔｈａｎｔｈａｔｏｆＳｎ ,ｓｏＡｌ ＳｎａｌｌｏｙｉｓｒｅｐｌａｃｅｄｂｙＡｌ Ｐｂａｌｌｏｙｉｎｔｈｅｆｉｅｌｄｏ…     

矿物掺和料对混凝土早期开裂的影响

针对高性能混凝土普遍存在的早期开裂问题,采用板式混凝土开裂架研究了掺硅灰、粉煤灰、矿渣粉对混凝土早期开裂的影响规律,同时测量了混凝土早期自收缩及在干燥条件下的总收缩。试验结果表明:掺硅灰对混凝土在干燥条件下的早期总收缩影响不大,但使混凝土早期开裂加重;掺粉煤灰使混凝土早期自收缩明显减小,而总收缩并不降低;掺矿渣粉使混凝土早期自收缩和总收缩都增大,而掺粉煤灰和矿渣粉均使混凝土早期抗裂性改善,且掺粉煤灰抗裂性优于矿渣粉。掺硅灰混凝土早期抗裂性差的主要原因是混凝土早期弹性模量增大,徐变和应力松弛能力降低;而掺矿渣粉或粉煤灰混凝土早期抗裂性改善的主要原因在于混凝土早期弹性模量减小、徐变和松弛能力提高。     

约束条件下高性能混凝土的早期开裂

早期收缩开裂是高性能混凝土，特别是大流动度混凝土施工应用中经常出现的质量通病。这种裂缝的产生主要与混凝土配合比、养护条件及混凝土所处约束条件有关。本文对掺硅灰、粉煤灰等矿物掺合料的高性能混凝土在约束条件下的早期开裂进行试验研究。结果表明：掺硅灰加剧了混凝土的早期开裂；优质磨细粉煤灰的加入对混凝土早期开裂有一定的抑制作用。     

水性聚氨酯荧光增白材料的合成及其性能研究

荧光增白剂可吸收不可见的紫外光,并且将紫外光转变为可见的蓝色或蓝紫色光发射出来;由于蓝色和黄色互为补色,消除了物质中的黄色部分,从而达到了增白效果。因此,采用荧光增白剂合成的水性聚氨酯(WPU)增白材料,用于涂料和织物上,可初步解决芳香族WPU的耐黄变问题。研究了乳液pH值、荧光增白剂的用量及其添加方式对WPU增白效果的影响,并通过透射电镜(TEM)观察增白剂在WPU中的分散情况。实验结果表明,WPU乳液及其胶膜的蓝光效果随着荧光增白剂用量的增加呈先增后降的趋势,当w(荧光增白剂)=0.008%时为最佳;当pH=7～9时,荧光增白剂在WPU中的分散稳定性和增白效果都较好;荧光增白剂的两种添加方式对其在WPU乳液及其胶膜中的分散稳定性和增白效果的影响不明显。     

Rating scales for the psychosocial evaluation of organ transplant candidates. Comparison of the PACT and TERS with bone marrow transplant patients

Two scaled formats for summarizing the results of psychosocial evaluations of transplant candidates have been published, the Psychosocial Assessment of Candidates for Transplantation (PACT) and the Transplant Evaluation Rating Scale (TERS). In this study, 40 consecutive candidates for bone marrow transplant were rated on the PACT and TERS. The PACT and TERS were comparable in interrater reliability. Similar conceptual items for each scale correlated fairly highly with one another. The PACT and TERS differ in several scale characteristics. The authors discuss the relationship between scale characteristics and clinical utility.     

Physiologic variations in lower extremity venous valvular function

We conducted this study to investigate the physiologic variations in venous valvular function and calf muscle pump function that occur in normal limbs after prolonged stationary standing. Twenty-two limbs from 11 healthy volunteers were studied after a brief period of activity and after 4 to 6 hours of stationary standing. Vein diameter, peak reflux flow velocity (PRFV), and valve closure time (VCT) were measured with duplex scanning in the standing position in the common femoral vein (CFV), superficial femoral vein (SFV), popliteal vein (POP), proximal greater saphenous vein (GSV), and greater saphenous vein at the knee (kGSV). Pneumatic rapid inflation-deflation cuffs were used to elicit reflux. Vein cross-sectional area (VA) and peak reflux volume (PRVol) were calculated. Venous volume (VV), venous filling index (VFI), ejection fraction (EF), residual volume fraction (RVF), and outflow fraction (OF) were measured with air plethysmography in all limbs. After stationary standing, there was no significant change or trend toward an increase in diameter or VA in any of the deep veins and there was no change in the PRFV or VCT. In the proximal GSV there was a significant increase in diameter (p = 0.0001) and VCT (p = 0.048) without a change in PRFV. No significant changes were noted in the kGSV. In the GSV the PRFV was significantly lower (p < 0.05) and the VCT significantly shorter (p < 0.05) compared with the SFV and POP but values were no different from those in the CFV. The PRFV was significantly higher in the SFV (p < 0.0001) and the POP (p < 0.002) compared with that in the CFV.(ABSTRACT TRUNCATED AT 250 WORDS)