‘红叶’杜仲叶色转变过程中叶片生理指标变化

【目的】研究‘红叶’杜仲不同时期叶片生理指标变化规律,为揭示其特殊叶色转变机理提供理论依据。【方法】以‘红叶’杜仲和‘小叶’杜仲为材料,选择5个时期进行叶片色素含量测定。分别测定叶绿素a、叶绿素b、总叶绿素、类胡萝卜素、类黄酮和花色苷含量。使用CR2500型色差计(日本MINOLTA公司)测定L(明度值)、a^*(变红度值)及b^*(变黄度值),利用a^*和b^*计算出色泽饱和度(Chroma,C^*)和色调角(hur angle,h),并进一步计算叶片颜色指数(color index)。对叶色转变过程及花色苷合成代谢途径中的关键酶苯丙氨酸裂解氨酶(PAL)和查尔酮异构酶(CHI)进行提取和酶活性测定,研究各时期差异显著性并通过相关分析研究各指标间的关联程度。【结果】① ‘小叶’杜仲虽与‘红叶’杜仲变化规律相似,但两品种各指标的初始值及变化幅度均存在显著差异。‘小叶’杜仲颜色指数始终属于黄绿级,而‘红叶’杜仲第1、2阶段属于黄绿级,第3、4阶段属于粉红级,第5阶段达到深红级。② 两个品种各种色素含量均为逐步上升,但在C_a(叶绿素a含量)、C_b(叶绿素b含量)、C_T(总叶绿素含量)、C_Car(类胡萝卜素含量)、C_f(类黄酮含量)和C_A(花色苷含量)这几种物质含量变化中,叶片颜色变红过程中最关键的是花色苷含量。分别比较两品种第5时期(38 d)相对于第1时期(6 d)各色素含量的增幅,得到‘红叶’杜仲的C_A增幅是‘小叶’杜仲的553.96%。③ 无论‘小叶’杜仲还是‘红叶’杜仲,不同时期的PAL酶活性无显著差异,且各时期两品种的酶活性值大小相近。而‘红叶’杜仲CHI酶活性随着叶色的转变直线上升,第5时期(38 d)为第1时期(6 d)的306.14%,不同阶段间差异达到极显著水平;‘小叶’杜仲CHI酶活性随着叶色转变也有逐步升高的趋势,但是增幅较小,不同时期的酶活性无显著差异。④ L、a ^*及b^*与类胡萝卜素含量、花色苷含量及类黄酮含量呈极显著相关,而与叶绿素a含量、叶绿素b含量、总叶绿素含量及叶绿素a与叶绿素b含量比无显著相关关系。CHI酶活性和杜仲叶片L、a^*、b^*、类胡萝卜素含量、花色苷含量及类黄酮含量间均存在显著或者极显著的相关关系,而PAL与叶片色差值间则无显著相关性。【结论】在‘红叶’杜仲叶片颜色转变过程中,花色苷含量变化幅度远大于叶绿素含量变化幅度,是其呈色的直接原因;‘红叶’杜仲CHI酶活性高在‘红叶’杜仲典型叶色转变过程中具有关键作用。     

低伤害小分子瓜尔胶压裂液性能研究

华北油田致密储层属于低孔低渗储层,需要压裂改造才能投产,但储层厚度小,孔吼半径小,在压裂过程中应特别关注入井流体对储层的伤害问题。提出采用分子量为常规瓜尔胶一半的小分子瓜尔胶作为压裂液的稠化剂的方法,以降低压裂液高分子稠化剂对储层孔吼的堵塞的伤害,提高改造效果。优选了与小分子瓜尔胶匹配的分散剂、助排剂、黏土稳定剂,形成了适应华北油田致密储层的低伤害小分子瓜尔胶压裂液体系。该压裂液体系可以在5 min内完全溶胀;该压裂液体系在130℃温度下剪切2 h后,黏度保持在80 m Pa·s以上,满足携砂的要求;压裂液体系在90℃可在90 min内完全破胶,破胶液粒径小于10μm;对华北油田致密岩心伤害率小于16%,残渣含量小于10%,对支撑剂导流带的伤害小于15%。可满足华北油田致密储层的压裂要求。     

Mechanical Reinforcement of Continuous Flow Spun Polyelectrolyte Complex Fibers

A simple continuous flow wet‐spinning method to achieve mechanical reinforcement of the two oppositely charged biopolymers chitosan and gellan gum is described. The mechanical properties of these biopolymers are influenced by the order of addition. Using a facile method for mechanical reinforcement of gellan gum/chitosan fibers resulted in increases in Young's modulus, tensile strength, and toughness. Spinning gellan gum into chitosan resulted in the strongest fibers. We show that our fibers can provide a mechanical alternative for bio‐fibers without the need of cross‐linking. It is demonstrated that the fibers become ionically conducting in the presence of water vapor.

     

Na_2S_2O_8-Fe~(2+)对田菁胶的氧化降解行为研究

考察了Na2S2O8-Fe2+对田菁胶的氧化降解行为,系统研究了Na2S2O8和Fe2+用量、温度、降解时间和pH值对田菁胶粘度的影响。结果表明,Na2S2O8和Fe2+合适的体积比为3?1。在较低的温度(40℃)和较短的时间(20 min)内Na2S2O8-Fe2+就能使田菁胶粘度下降90%以上。另外,Na2S2O8-Fe2+氧化还原体系在酸性和中性条件下对田菁胶的降解都有良好的降解性能,考虑到在实际生产中的应用,我们认为中性条件下最合适。     

陕西略阳杜仲叶中绿原酸的含量分析

测定了陕西略阳杜仲叶中绿原酸的含量,为陕西略阳杜仲产业发展提供基础研究数据和分析技术支持。采用微波提取,设置微波功率200W,压力1000kPa,温度60℃,提取5min;高效液相色谱法分析检测,设置色谱条件为Diamonsil C18柱(4.6mm×150mm,5μm),327nm检测波长,流动相为乙腈∶0.3%磷酸=15∶85,1mL/min流速,30℃柱温。采用微波提取法处理样品,绿原酸提取效率高;HPLC分析方法通过方法学考察符合分析要求;陕西略阳杜仲叶中绿原酸含量在1.85%—3.18%之间。陕西略阳杜仲叶中绿原酸的含量远高于药典要求,可单独作为药材使用,亦可作为绿原酸提取原料使用,具开发利用价值。     

浸提法提取胶母糖中铅的测定方法

通过采用硝酸过氧化氢过夜浸提改进胶母糖样品中测定铅的前处理方法,基体干扰少,三水平加标回收率在95.2%～110.3%,8次重复测定的变异系数为1.8%,与国家标准方法比较,采用t检验法分析,结果无显著性差异.     

Synthesis of Novel Nanocomposites of Silica and Guar Gum:Efficient Zinc Ion Binder

1 Results Adsorption using commercial activated carbon (CAC)[1] can remove heavy metals from wastewater[2-4].However,CAC remains an expensive material for heavy metal removal.Ion exchange techniques are also used but it generates volumetric sludge and increases the cost[5].Using naturally occurring seed polysaccharides can solve these problems but their solubility in water limits its application as an adsorbent.Guar gum is a commercially available,industrially important[6-7] polysaccharide material havi...     

Graft Copolymerization of Poly(ethyl Acrylate) onto Wool in the Presence of Ceric Ammonium Nitrate as Redox Initiator

Poly(ethyl acrylate) has been grafted onto Himachali wool in an aqueous medium by using ceric ammonium nitrate (CAN) as redox initiator. Copolymerization was studied at five different temperatures: 40, 45, 50, 55, and 60°C. Maximum grafting occurred at 45°C. Nitric acid was found to catalyze the graft copolymerization reactions. Percentage and efficiency of grafting were found to be dependent upon concentrations of CAN (initiator) and of monomer. Percentage of grafting has been determined as function of time, and from the slope of percent grafting versus time plot, the initial rate of graft copolymerization (R) has been determined.     

Reaction of Acenaphthylene with the Benzoyloxy Radical

Acenaphthylene (ACN) has been polymerized at 60° C using benzoyl peroxide labeled with carbon-14 and tritium as the Lnitiator. End-group analyses show a very high proportion of benzoate groups among the incorporated initiator fragments. It is deduced that ACN is much more reactive than most other monomers toward the benzoyloxy radical. There is evidence that transfer to benzoyl peroxide is significant during the polymerization of ACN.