氯化钙/甲酸溶解体系下丝素纳米纤维的制备及其性能

采用氯化钙/甲酸（FA）溶解体系溶解脱胶蚕丝形成丝素溶液,再将溶液干燥、去盐,将丝素膜在甲酸溶液中二次溶解获得丝素质量分数分别为4%、6%、8%的纺丝液。采用滚筒收集装置进行静电纺丝,讨论不同质量浓度丝素溶液的纺丝性能,通过SEM、红外以及体外降解等测试手段表征丝素纳米纤维的性能。结果表明：低质量分数（4%）纺丝液的黏度较低,会出现不连续液滴,高质量分数（8%）纺丝液所纺纤维直径较粗;实验所用丝素质量分数为6%的纺丝液纺成的纤维成形效果良好,直径主要集中在150~250 nm区域内。红外分析表明：经75%乙醇处理会促进丝素分子构象由α-螺旋向β-折叠的转变。降解实验表明,纤维在PBS溶液中降解60 d后质量损失15%,纤维粗细不均匀且发生黏连;在放线菌蛋白酶溶液中降解48 h后质量损失96.9%,纤维几乎完全降解,降解程度较PBS溶液中更明显。

溶剂萃取法萃取磷酸的研究

对溶剂萃取法制取磷酸的萃取剂进行了筛选，选择出了一种较好的萃取剂ＴＢＰ。利用比浊法测定了２５℃及５０℃时ＴＢＰ—Ｈ３ＰＯ４—Ｈ２Ｏ三元体系的液－液平衡数据，同时测定了该体系在上述温度的结线数据。研究了ＣａＣｌ２对磷酸在两相中分配的影响。实验表明，该三元体系具有较大的分层区域，低温有利于磷酸的萃取，ＣａＣｌ２的存在促进了ＴＢＰ对磷酸的萃取。

诱导子对人参毛状根中皂苷含量的影响

目的 :研究诱导子水杨酸 (SA)、酵母提取物 (YE)、AgNO3和CaCl2 对人参PanaxginsengC .A .Meyer毛状根皂苷含量的影响。方法 :用紫外法测定总皂苷的含量 ,高效液相色谱法测定 4种单体皂苷的含量。结果 :SA能明显促进Rb1、Re、Rg1和Rd 4种单体皂苷的积累 ,而且能促进人参皂苷分泌到细胞外并在培养液中积累。YE和 10mmol/LAgNO3不但能促进人参毛状根中总皂苷含量和单体皂苷的积累 ,还能促进人参皂苷的外泌。CaCl2 在较低浓度下 ( 1.0mmol/L)明显促进总皂苷和单体皂苷的积累 ,但随着CaCl2 浓度的增高这种促进作用呈下降趋势。结论

几种外源物质对盐胁迫下火力楠幼苗生理特性的影响

以1年生火力楠幼苗为试材,通过甜菜碱(BT)、氯化钙(CaCl_(2))、茉莉酸甲酯(MeJA)和水杨酸(SA)4种外源物质进行处理,研究其对300 mmol·L^(-1) NaCl胁迫下火力楠幼苗相对电导率、叶绿素、可溶性糖和蛋白质量分数、过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)活性的影响。结果表明:(1)单盐胁迫下火力楠幼苗的相对电导率、SOD活性显著升高,可溶性糖质量分数和CAT活性升高,POD活性先升高后下降,叶绿素、可溶性蛋白质量分数下降。(2)喷施适宜浓度的不同外源物质后叶片相对电导率显著降低,可溶性糖和可溶性蛋白质量分数明显增多,CAT、POD、SOD活性显著增强,叶绿素质量分数变化不大。(3)利用隶属法进行综合评价结果显示4类外源物质缓解火力楠幼苗盐伤害作用效果排序由大到小为MeJA、SA、CaCl_(2)、BT。喷施外源3 mmol·L^(-1) MeJA最能减少盐胁迫对火力楠幼苗的伤害,其次为100 mg·L^(-1) SA、5 mmol·L^(-1) CaCl_(2)处理。

Effect of crude methanol leaf extract ofCombretum racemosum on histamine-stimulated gastric secretion in rats

Objective:To investigate the effect of crude methanolic extract of Combretum racemosum (C. racemosum) leaves on histamine-stimulated gastric secretion in rats. Methods: Phytochemical and acute toxicity tests were performed. Anti-secretory activity of C. racemosum extract was investigated in pyloric ligated rats administered histamine. Gastric juice was collected from all the animals and the volume, titratable acidity, pH and mucus content were measured. The effect of C. racemosum extract on calcium chloride induced contractions of the guinea-pig ileum suspended in high potassium, calcium-deficient depolarizing solution was investigated. The H2 receptor antagonistic potency was also evaluated using the isolated non-gravid rat uterus. Results:Phytochemistry revealed the presence of abundant amounts of saponins and moderate amounts of glycosides, terpenoids, proteins, reducing sugar, resins, alkaloids, flavonoids and carbohydrates. The oral LD50 of the extract was greater than 8000 mg/kg body weight in mice. Pretreatment of pyloric ligated rats with C. racemosum prior to histamine administration significantly reduced (P < 0.001) the volume of gastric juice and titratable acidity, and significantly increased (P < 0.001) gastric pH and gastric mucus when compared to the negative control. Both doses ofC. racemosum protected rats significantly (P < 0.001) from histamine-induced ulceration.C. racemosum potently inhibited contractions evoked by calcium chloride in a dose-dependent and reversible manner with an IC50 of 1132μg/mL.It also antagonized the relaxant effect of histamine on the isolated rat uterus in a manner comparable to cimetidine. Conclusions: The leaves of C. racemosum possess gastric anti-secretory and anti-ulcer effects and justify its use in traditional medicine in South-East Nigeria for the treatment of peptic ulcer disease.