南瓜色素紫外-可见光谱研究

本文使用不同的溶剂对南瓜果肉色素进行提取,并得到不同溶剂的色素提取溶液。运用紫外光谱法对不同溶剂的色素提取溶液进行分析,并选取甲醇提取的色素溶液,调节其pH值,进行紫外光谱分析。初步确定了不同溶剂提取的色素溶液中可能含有的一些基团,并得出南瓜色素是由多种成分组成,且不同溶剂提取的色素组成也有差别。在对甲醇提取的色素溶液在不同pH下进行光谱分析后,发现pH值对甲醇提取的色素稳定性影响不大。     

不锈钢丝刷电极电解还原硝基苯废水

研究了以石墨电极作阳极、不锈钢丝刷为阴极、Na2SO4为电解质,采用不同电解电压（20 V、5 V）对模拟硝基苯（NB）废水进行电解。测量了不同电解时间溶液的紫外光谱,结果表明：20 V电压时,硝基苯被还原为苯胺（AN）;而5 V电压时,产物除苯胺外,可能还有马来酸、对氨基苯酚、对苯二酚等。对20 V电解电压的体系,采用双波长等吸收消除干扰法求解出不同电解时间混合体系中硝基苯和苯胺各自的含量;而对5 V的电解体系,采用萘乙二胺偶氮光度法来测定电解处理后废水中苯胺和硝基苯的含量。结果显示,随着电解电压的下降,除产物成分变化外,硝基苯转化率、最大转化率需要的时间也发生变化。     

Pollen Sensitivity to Ultraviolet-B Suggests Floral Structure Evolution in Alpine Plants

<正>The diversifi cation and evolution of fl oral traits are driven by both biotic and abiotic agents.The most well-studied agent is rain,which can wash away pollen grains,reduce pollen viability and dilute nectar thus affecting the reproductive fitness directly or indirectly.Strong ultraviolet radiation(especially UV-B radiation)is also known to reduce pollen viability,and strong UV-B radiation is a typical characteristic of alpine environments;accordingly,it may exert selection pressures on fl oral traits of alpine plants as well.However,the influence of UV-B radiation on the evolution of flower structure remains relatively unexplored.According to previous research,the reflexed flower stalk of Anisodus luridus during anthesis     

分光光度法测定八角总黄酮含量的教学实验

介绍了一个具有可推广性的分析化学研究型教学实验一分光光度法测定八角中总黄酮含量。该实验涉及分析化学、有机化学、无机化学、天然药物化学领域的知识与操作,有助于巩固学生原有的知识与实验技能,培养学生分析问题、解决问题的能力。推荐该实验作为本科生的分析化学研究型教学实验。     

分光光度法测定茶叶与红枣中铁的含量

采用邻二氮菲分光光度法测定茶叶与红枣中铁的含量。结果显示,铁标准溶液在0～2μg/mL浓度范围内,标准曲线呈较好的线性关系,茶叶及红枣中铁含量均较高。研究结果可为人们合理饮用茶叶、食用红枣、补充微量铁提供参考。     

滨海地区土壤重金属Cr,Cu,Pb和Zn的状况

为研究上海市临港新城土壤生态,从临港新城主城区及周边地区31处采集土壤,测定土壤中Cr,Cu,Pb和Zn等4种重金属元素的地理分布特征,并利用单项污染指数和内梅罗污染指数评价4种金属的污染程度.研究结果表明:表层土壤中4种金属元素含量由沿海至内陆呈先增加后降低的趋势;而深层土壤中Cr和Pb含量由沿海至内陆呈增加的趋势,...     

3,5-二溴-2-吡啶偶氮重氮氨基偶氮苯固相萃取光度法测定生物样品中镉的研究

研究了用3,5-二溴-2-吡啶偶氮重氮氨基偶氮苯(3,5-DB-PDAB)固相萃取光度法测定镉,在pH=10的硼砂-氢氧化钠缓冲介质中,TritonX-100存在下,3,5-DB-PDAB与镉反应生成2:1稳定络合物,体系最大吸收波长为528nm,摩尔吸光系数ε=1.65×105L.mol-1.cm-1,样品中的镉用强阴离子交换固相萃取柱固相萃取预分离和富集后用该方法测定,结果令人满意.     

纳米氧化锌紫外光解水体中的亚甲基蓝

以商洛某铅锌尾矿库的铅锌冶金炉窑渣制得的纳米ZnO为光催化剂,研究了其对水体中亚甲基蓝(MB)的光催化降解作用,探讨了紫外降解废水中亚甲基蓝的过程与性质,并对紫外降解工艺进行优化。结果表明:当纳米ZnO光催化剂用量为1.0 g,紫外降解2.5 h时,亚甲基蓝的分解率可达99.7%。亚甲基蓝的降解历程推测可能为:ZnO紫外降解亚甲基蓝时,活性羟基自由基(·OH)起氧化作用,将发色基团的巯基(-S-)氧化为吸收波长低于180 nm的砜基,完成亚甲基蓝的脱色降解。     

Vitamin D and the athlete: Emerging insights

Abstract

Interest in Vitamin D has risen considerably recently with many athletes now advised to take daily vitamin D supplements. The reason for this interest is partly not only attributed to the resurgence of the Vitamin D-deficient disease rickets but also due to the discovery of a Vitamin D receptor in many tissues suggesting a more global role for Vitamin D than previously considered. Unlike the other vitamins that are obtained through the diet, Vitamin D is unique since endogenous synthesis following ultraviolet B (UVB) exposure is the predominant route of entry into systemic circulation. Moreover, Vitamin D could be better classed as a seco-steroid, given that its structure is similar to that of a steroid, and its production is derived from a cholesterol precursor (7-dehydrocholesteol) in the skin. The classification of Vitamin D status is currently subject to considerable debate with many authors opposing governing body recommendations. Regardless of the suggested optimal concentration, there is now growing evidence to suggest that many athletes are in fact Vitamin D deficient, especially in the winter months largely as a consequence of inadequate sun exposure, combined with poor dietary practices, although the consequences of such deficiencies are still unclear in athletic populations. Impaired muscle function and reduced regenerative capacity, impaired immune function, poor bone health and even impaired cardiovascular function have all been associated with low Vitamin D in athletes, however, to date, the majority of studies on Vitamin D have described associations and much more research is now needed examining causation.     

紫外线诱变选育高产柠檬酸黑曲霉

为了选育能利用纤维素产酸的黑曲霉,拓展柠檬酸发酵生产的原料。通过紫外线(UV)诱变选育柠檬酸产量提高的菌株,结果表明,紫外诱变获得了一株遗传性能稳定的优良菌株UV-4,产酸为26.77±0.67g/L,与出发菌株相比产酸增幅达50.39%,且UV-4利用稻草纤维素产酸达10.055±0.42 g/L,较出发菌株提高28.04%。