野油菜黄单孢菌的诱变育种及发酵培养基的确定

利用紫外线和氯化锂对野油菜黄单孢菌进行诱变,从诱变菌株中筛选出了1株具有较高粘度和产胶率的菌株ZG 1.同时,利用此菌株通过正交试验,确定了发酵培养基配方:淀粉2%,蔗糖2%,蛋白胨0 3%,豆饼粉0 2%,CaCO3,0 3%,柠檬酸0 1%.试验结果表明:菌株的最终发酵液粘度和产胶率由初始的4 5Pa·s和1 99%提高到12 28Pa·s和3 45%.     

杜仲胶/天然橡胶并用硫化胶的力学性能

采用常规硫化方法,将杜仲胶(EUG)与天然橡胶(NR)共混硫化,研究不同EUG含量对并用硫化胶的力学性能、应力软化效应及动态力学性能的影响;并通过差示扫描量热法(DSC)对内部结晶进行表征,通过扫描电子显微镜(SEM)对硫化胶拉伸断面进行观察。实验结果表明,加入EUG使得并用硫化胶的断裂伸长率和拉伸强度都有所下降、应力和应变也逐渐降低;100%定伸应力和300%定伸应力增加;应力软化现象提高;玻璃化转变温度(T_g)向低温移动,储能模量降低。通过SEM的观察和DSC测试可知硫化胶内部含有部分结晶。     

The depression behavior and mechanism of tragacanth gum on chalcopyrite during Cu-Mo flotation separation

In this work, tragacanth gum (TG), a nontoxic and environmental friendly organic polymer, was used to replace the traditional inorganic depressants of chalcopyrite during the flotation separation of copper-molybdenum sulfides. The single mineral flotation and artificial mixed minerals flotation experiments were conducted to investigate the effect of TG on flotation separation behaviour of molybdenite and chalcopyrite. The TG’s adsorption mechanism on molybdenite and chalcopyrite was investigated by X-ray photoelectron spectroscopy (XPS) and Time-of-flight secondary ion mass spectrometry (ToF-SIMS). The flotation experiment results showed that at pH 3–8, TG had a significant selective depressive effect on chalcopyrite flotation and it was enhanced with increasing TG concentration, but hardly affected the molybdenite flotation. XPS analysis showed that TG was chemically adsorbed on both molybdenite and chalcopyrite surfaces and ToF-SIMS results demonstrated that the interaction of TG and chalcopyrite was stronger than that of TG and molybdenite. Further, XPS narrow scanning analysis suggested that TG might chemisorb onto chalcopyrite via chemical bond between the carboxyl groups and Fe sites on bulk chalcopyrite surface as well as the hydrogen bond between the hydroxyl groups and surface Fe oxides/hydroxides. The strong TG adsorption on chalcopyrite hindered the subsequent adsorption of PBX on chalcopyrite surface, thus chalcopyrite was significantly depressed and Cu-Mo flotation separation was achieved.     

The Effect of Formulation on Radioiodide Thyroid Uptake in the Hyperthyroid Cat

This investigation was designed to compare in vitro dissolution profiles from sodium iodide capsules with radioiodide thyroid uptake in hyperthyroid cats using sodium iodide capsules prepared with a formulation exhibiting a complete release of radioiodide (I-123) in vitro and a formulation with an incomplete release of radioiodide. In vitro dissolution profiles for I-123 sodium iodide capsules with two different formulations were determined using the USP XXIII dissolution test. The two formulations studied in vitro were sodium phosphate dibasic powder with 1% magnesium stearate and calcium phosphate dibasic powder with 3% magnesium stearate. By 20 min after initiation of the dissolution test, over 95% of the I-123 was released from capsules of sodium phosphate dibasic powder. The capsules of calcium phosphate dibasic powder reached 75% at 65 min, with no further release occurring thereafter. There was a statistically significant difference in the dissolution profiles of the two formulations. The thyroid uptake of I-123 from capsules exhibiting complete release and incomplete release of radioiodide was determined in hyperthyroid cats. At 4 hr, the mean percentage thyroid uptake value for sodium phosphate dibasic powder with 1% magnesium stearate (complete release formulation) was 12.0% compared to 9.4% for calcium phosphate dibasic powder with 3% magnesium stearate (incomplete release formulation); at 24 hr, the values were 34.4% compared to 23.7%. The data suggest that the incomplete dissolution profile observed in vitro may correlate with a reduction in the bioavailability of the radioiodide in vivo. However, using the Wilcoxon signed rank test, statistically significant differences did not occur between the complete release formulation and incomplete release formulation at either 4 hr or 24 hr (p >. 05). The results of the in vivo study with five hyperthyroid cats were not conclusive due to the variability in response between individual cats.     

精准温控技术对蟠桃冷藏和常温货架品质的影响

目的 将精准温控技术应用于蟠桃冷藏和常温货架中,以研究其保鲜效果.方法 以北京平谷蟠桃为材料,设立对照组和3个精准温控组,将蟠桃装入普通泡沫箱,记为CK(Control Kheck)组,普通泡沫箱+蓄冷剂记为冰温1组,精准温控保鲜箱记为冰温2组,精准温控保鲜箱+蓄冷剂记为相温组.每10 d测量1次,并进行3 d常温货架实验,分析其呼吸强度、乙烯生成速率、果肉色泽、营养物质(Vc、可滴定酸、可溶性固形物)、相对电导率的变化.结果 精准温控技术可使温度波动范围更小,其中相温组的温度波动最小,在整个冷藏期间,CK组、冰温1组、冰温2组和相温组的箱内温度分别为(0.06±0.30),-(0.14±0.16),-(0.09±0.14),-(0.21±0.06)℃,在冷藏期和常温货架期内,腐烂指数和褐变指数呈上升趋势,CK组最先出现腐烂和褐变现象,且腐烂指数和褐变指数均大于冰温组和相温组,相温组感官品质最优,与CK组相比较,其他3组处理均可以降低果实呼吸强度,抑制乙烯生成速率,维持果实营养物质在较高水平,通过SPSS分析,综合得分依次为CK组<冰温1组<冰温2组<相温组,其中相温组的保鲜效果最好.结论 精准温控技术有利于蟠桃的冷藏和常温货架保鲜,其中相温组的贮藏效果更好.     

不同处理方式下膨化玉米粉的冲调性能分析

该研究以膨化玉米粉为原料,分析磷酸化、酶处理、食用胶干热和复合处理对膨化粉吸水性指数、水溶性指数、分散时间、结块率、黏度、粒径和色度的影响。结果表明,磷酸化热处理对膨化粉黏度无显著影响;食用胶干热处理黏度增加;酶处理及其与磷酸化、食用胶干热复合处理吸水性指数和黏度显著降低,水溶性指数大于磷酸化和食用胶干热处理。α-淀粉酶处理粉的水溶性指数从30.4%增至80.98%,吸水性指数从4.96降至1.21。黄原胶α-淀粉酶、α-淀粉酶正磷酸钠复合处理膨化粉结块率分别为1.63%、1.46%,低于正磷酸钠、α-淀粉酶、中性蛋白酶、黄原胶干热处理粉结块率,分别为5.57%、5.60%、6.16%、5.58%,两种复合处理方式下黏度较稀,分别为83.33 mPa·s、100 mPa·s;正磷酸钠、黄原胶干热处理黏度分别为2243.33 mPa·s、306.33 mPa·s,正磷酸钠联合中性蛋白酶处理黏度、结块率分别为546.67 mPa·s、4.89%,黏度适中,结块率低于单一处理,此时分散时间、粒径分别为4.81 s、131.14μm,呈淡黄色。综合分析,正磷酸钠中性蛋白酶复合处理下膨化米粉冲调...     

超高压处理对桃汁挥发性化学成分的影响

利用超高压装置(400 MPa,25℃,20 min)处理桃汁,采用顶空固相微萃取与毛细管气相色谱-质谱联用技术检测桃汁中的挥发性成分,并用面积归一化法测定了各种成分的相对质量分数。经与超高压处理前桃子原汁的41种主要香气成分分析比较发现,超高压处理后桃汁中主要特征香气成分的质量分数明显增加,其中γ-己内酯、cis-2-己烯醇、γ-癸内酯、叶醇和己醇等物质的质量分数分别增长了41.7%、52.0%、109.5%、288%、313.1%,并且新增加了乙酸己酯(0.29%)、cis-2-己烯醇乙酸酯(0.13%)、cis-3-己烯醇乙酸酯(0.47%)和十八醛(0.41%)等香气成分;感官评定表明,桃汁的青鲜香气更加突出,说明超高压处理增强了桃汁的特征香气。     

羧甲基香豆胶的制备与表征

通过加入NaOH与一氯乙酸钠(SMCA)固体进行香豆胶(FG)的碱化和醚化,制备了不同取代度的羧甲基香豆胶(CMFG)。研究了不同分散介质、反应温度与时间、NaOH与SMCA用量等因素对取代度与反应效率的影响。以异丙醇/水为分散介质,产物取代度与反应效率最大,优化的反应温度为50℃、反应时间5h、醇水体积比52.5∶7.5。醇水体积比为50∶10、n(SMCA)∶n(NaOH)∶n(FG)=1∶1∶1时取代度为0.75,反应效率达75%。NaOH对取代度的影响大于SMCA。采用一步羧甲基化反应制备取代度1.05的CMFG,反应效率可达到70%。CMFG溶液黏度随取代度增大而增大,w(CMFG)=2%时,取代度为0.78,溶液黏度为116mPa.s。CMFG水溶液黏度4d降低8.6%～28.0%,黏度稳定性高于在w(NaCl)=1%的盐水溶液中的稳定性。     

浩伦松碱合剂防治柑桔蚧壳虫的田间应用

通过在3个省份的田间试验充分表明,浩伦松碱合剂是防治柑桔蚧壳虫的良好药剂。推荐使用45％浩伦松碱合剂4500—5625mg／kg的剂量较好,在药后15d对柑桔蚧壳虫的防效为86．95％～89．11％。     

利用桃汛洪水降低潼关高程原型试验效果分析

介绍了2006年利用并优化桃汛洪水降低潼关高程原型试验的过程,指出其试验效果主要有：①使潼关高程冲刷下降0．2m;②减少了万家寨水库的淤积,改善了水库的淤积形态;③实现了天桥水库的冲刷;④基本实现了小北干流河段全程冲刷;⑤改善了三门峡水库淤积部位。