6-氯-8-烃基-9-芳基嘌呤类衍生物的合成

以4,6-二氯-5-氨基嘧啶为原料,经N-烃基化反应、缩合反应和氯化反应,合成了一系列未见文献报道的6-氯-8-烃基-9-芳基嘌呤衍生物,所有化合物均通过1H NMR、MS和元素分析确定其结构。 研究结果表明,N-烃基化反应时,芳胺使用盐酸作催化剂,芳基脂肪胺用有机碱三乙胺作催化剂,缩合反应时,多聚磷酸(PPA)用量过多会影响传质效果,影响反应的收率。 讨论了微波反应方式对氯化反应的影响。     

自蔓延高温合成法制备Ni-Al基金刚石复相材料

利用自蔓延高温合成法,以Ni粉、Al粉和金刚石为原料,制备Ni-Al基金刚石复相材料.利用XRD、SEM、DSC表征手段,分析研究自蔓延反应产物的物相、组织结构以及微观反应过程.研究表明:试样在600℃、700℃、800℃能够被引燃发生自蔓延反应;当Ni、Al摩尔比为1∶1时,NiAl为其SHS反应产物;当Ni、Al摩尔比为3∶1时,其SHS反应产物为Ni3Al、NiAl.适量的金刚石对两种配比的Ni-Al体系反应放热存在一定减缓作用,但不影响最终产物.不同配比的Ni-Al体系生成的主晶相—NiAl基体、Ni3Al基体能够与金刚石紧密结合.     

基于TG-FTIR的杨木热解过程中脲醛树脂影响机理的模型物研究

热解是废弃人造板高效回收利用的方式,人造板中所含胶黏剂是其不同于生物质的主要特征。为了有效环保地利用热解技术处理废弃人造板,解明人造板热解过程中其所含脲醛树脂胶黏剂(UF)对木材热解特性的影响,深入探索UF对人造板中木材各组分的作用机制,以杨木及木材的三种主要组分(纤维素、半纤维素、木素)为研究对象,创新性地依据杨木的化学组成,以纤维素、木聚糖和木素配制成模型物,并加入UF模拟人造板的构成。利用热重红外光谱联用(TG-FTIR)分析法,对比分析了加入UF前后模型物以及杨木各主要组分的热失重特性及气相演变规律。热重及红外结果表明,UF促进了纤维素热解过程中水和羧酸类物质的生成。UF与木素结合生成热不稳定的含氮结构,释放大量氨气,并且在200～300 ℃区间内参与了木素的热解并直接影响木素热解产物的生成。由此推测,在人造板热解过程中,木材三种主要组分中与UF作用的主要成分是木素。     

KH（X^1Σ^＋,V＇＇=14-21）高位振动态与CO2碰撞速率系数的测定

在K-H2和CO2的混合系统中,利用404 nm脉冲激光器激发K原子至K（5P）态后其与H2发生反应,产生KH（X^1Σ^＋,V=0-3）分子.采用泵浦-探测技术,利用OPO脉冲激光器作为＂泵浦＂激光,泛频激发X^1Σ^＋（V=0）至高位振动态（V=14-21）,钛宝石激光器作为探测激光激发KH（X^1Σ^＋）至激发态KH（A^1Σ^＋）,在与激光束垂直方向测量A^1Σ^＋（V）→X^1Σ^＋（V）的激光感生荧光光谱（LIF）,得到KH（V）与CO2碰撞的猝灭速率系数,得出猝灭速率系数与KH振动量子数V有关系.     

碳掺杂的二氧化钛纳米管的制备及其可见光催化性能

以尿素作为碳元素前驱体对TiO2纳米管进行掺杂,采用比表面积测定、X射线衍射、透射电子显微镜、能量色散X射线荧光光谱、X射线光电子能谱、固体漫反射紫外-可见吸收光谱和荧光光谱对产物进行了表征。 结果表明,以尿素作为前驱体可制备C掺杂的TiO2纳米管,C掺杂后,TiO2纳米管的可见光催化活性明显提高。 此外,研究了C掺杂量、煅烧温度、催化剂用量和pH值对TiO2纳米管光催化降解活性的影响,发现当C的掺杂量为5.3%、催化剂用量为1.5 g/L、溶液的pH值为5时,在其催化作用下,可见光光照3 h后罗丹明B的降解率可达到91%。     

Effects of Combinatorial Expression of selA,selB and selC Genes on the Efficiency of Selenocysteine Incorporation in Escherichia coli

In Escherichia coli, four gene products(selA, selB, selC and selD) and a selenocysteine(Sec) insertion sequence(SECIS) are required for the correct translation of UGA codons encoding Sec. Previous studies have shown that the stoichiometry of selenoproteine mRNA and elongation factor SelB affect the efficiency of Sec incorporation. Herein lies a detailed analysis of the effects of co-expressing selA, selB and selC genes under inducible promoters on the incorporation efficiency of Sec. Over-expression of either selA or selB reduced the efficiency of Sec incorporation by 61.1% or 11.6%, respectively, compared to the over-expression of the reporter vector alone did. Concomitant over-expression of selC with selA or selB completely reversed the reduce of the efficiency of Sec but still reduced the efficiency of the incorporation relative to that observed for expression of selC alone. Over-expression of selC gene alone under L-arabinose induction reduced the efficiency of the incorporation relative to that observed for co-expressing selC with selA and selB under the control of its endogenous promoter in the absence of L-arabinose. Co-expression of selA, selB and selC with selA or selB under the control of inducible promoters increased the efficiency of Sec incorporation by 69.7%. Moreover, inducing selenoprotein-related gene expression during the late exponential phase increased the efficiency of Sec incorporation by a factor of 5.4 relative to that observed for the reporter vector alone. These results suggest that the co-expression of selA, selB and selC in Escherichia coli under the control of inducible promoters is a viable and promising strategy for increasing the yields of selenoproteins.     

Determination of Sex Hormones in Antler Velvet by High Performance Liquid Chromatography Tandem Mass Spectrometry

Eighteen sex hormones in antler velvet were determined by high performance liquid chromatography tandem mass spectrometry.The solid phase extraction was applied to eliminating the matrix effect.The exp...     

Evaluation of Stabilization Performances of Antioxidants in Poly(ether ether ketone)

Two types of antioxidants(a primary antioxidant and a secondary antioxidant) were used to improve the stability of poly(ether ether ketone)(PEEK). The effects of the antioxidants on the properties of PEEK and the stabilization mechanism were investigated by some characterization methods, such as rheometer, thermogravimetric ana- lysis(TGA), universal tester and electron spin resonance(ESR). The results indicate that the efficiency of the phosphorous antioxidant(DS) in improving the stability of PEEK was better than that of the phenolic antioxidant(DN) in both melting stability and thermal stability, and the thermal stability of PEEK sample containing 0.07%(mass fraction) DS was the best among all the samples due to the decrease of the free radicals density, as proven by ESR measurement. Additionally, no obvious changes could be observed in mechanical properties of PEEK containing antioxidants compared to those of virgin PEEK.     

无溶剂超声辐射下硝酸镱高效催化合成 1,4-二氢吡啶衍生物

在Yb(NO₃)₃催化下, 芳香醛、 5,5-二甲基-1,3-环己二酮、 乙酰乙酸乙酯和醋酸铵在室温无溶剂条件下经超声辐射一锅法合成了一系列1,4-二氢吡啶衍生物, 反应时间为15~35 min, 产率为86%~97%. 该方法具有条件温和、 反应时间短且产率高的优点. 催化剂Yb(NO₃)₃对环境友好且可循环使用, 为此类化合物的合成提供了一种有效的新方法.     

2[(N-乙基)-1-吩噻嗪基]腙的合成及聚集荧光增强性能

以氮-氮单键连接2个吩噻嗪环构成共轭结构, 合成了2[(N-乙基)-1-吩噻嗪基]腙, 并对其进行了结构表征. 该化合物在四氢呋喃溶剂中呈分散态时无荧光; 在四氢呋喃/水混合溶剂中呈现聚集荧光增强. 荧光增强是由于聚集态中分子内单键旋转受分子堆积效应的阻碍, 氮-氮单键连接的2个吩噻嗪环趋于平面化以及J-聚集体形成的协同作用使非辐射跃迁减少所致. 同时, 利用这种聚集荧光增强性质考察了该化合物对血红蛋白的探针识别性能.