Stability of isoflavone daidzein and genistein in riboflavin, chlorophyll b, or methylene blue photosensitization

ABSTRACT:  Effects of photosensitizers including riboflavin, chlorophyll b , or methylene blue on the stability of daidzein and genistein were studied in model systems by high-performance liquid chromatography (HPLC). Concentration of daidzein and genistein in 80% methanol with riboflavin under light for 7 h was significantly decreased with the apparent 1st-order rate constants of 0.234 and 0.193/h, respectively, ( P < 0.05), while those without riboflavin under light did not change significantly ( P > 0.05). The stability of isoflavone aglycones in the dark did not change significantly irrespective of the presence of riboflavin ( P > 0.05). The concentrations of daidzein and genistein in chlorophyll b or methylene blue model systems under light were not significantly different from those in the dark for 7 h ( P > 0.05). Addition of sodium azide increased the stability of daidzein and genistein in riboflavin photosensitization with concentration dependent manner. However, the protective effects of β-carotene addition on the photodegradation of isoflavones were not high. The stability difference of daidzein and genistein in riboflavin photosensitization may be due to the high reactivity of riboflavin through type I pathway, although singlet oxygen may be involved in part.     

Textural properties of gelling system of low-methoxy pectins produced by demethoxylating reaction of pectin methyl esterase

ABSTRACT:  After deesterification of commercial pectins with a pectin methyl esterase (PME), their gelling properties were characterized using instrumental texture analysis. The final degree of esterification (DE) of the high- and low-methoxy pectins reached approximately 6% after the PME treatment, while deesterification of low-methoxy amidated pectin stopped at 18% DE. Furthermore, DE of high-methoxy pectin was tailored to be 40%, which is equivalent to the DE of commercial low-methoxy pectin. As a result, significant changes in molecular weight (Mw) distribution were observed in the PME-treated pectins. The texture profile analysis showed that PME modification drastically increased hardness, gumminess, and chewiness, while decreasing cohesiveness and adhesiveness of the pectin gels ( P < 0.05). The pectin gel with relatively high peak molecular weight (Mp, 3.5 × 10⁵) and low DE (6), which was produced from high-methoxy pectin, exhibited the greatest hardness, gumminess, chewiness, and resilience. The hardness of low-methoxy amidated pectin increased over 300% after PME deesterification, suggesting that the effects of amide substitution could be reinforced when DE is even lower. The partial least square regression analysis indicated that the Mw and DE of the pectin molecule are the most crucial factors for hardness, chewiness, gumminess, and resilience of gel matrix.     

LiFe[Fe（CN）6]作锂离子电池材料的研究

普鲁士蓝锂铁衍生物具有完美的立方晶体结构,在晶体结构中存在空隙,为锂离子的嵌脱提供了可能。测试了该材料的电导率和锂离子在其中的嵌入／脱嵌能力,并对以其作为正极材料的锂离子电池样品进行了充放电测试。结果表明,该材料适合作为锂离子电池正极材料。     

基于可视化环介导等温扩增技术快速检测金黄色葡萄球菌

应用环介导等温扩增技术（loop-mediated isothermal amplification,LAMP）建立基于颜色判定的快速、灵敏的金黄色葡萄球菌检测方法。根据金黄色葡萄球菌特异性靶基因SAR0395设计LAMP引物,建立可视化LAMP检测方法。优化的反应体系为：1.6 μmol/L内引物（FIP和BIP）,0.2 μmol/L外引物（F3和B3）,4.0 mmol/L MgSO4,1.0 mmol/L dNTPs,0.4 U/μL Bst 2.0 WarmStart? DNA聚合酶,120 μmol/L羟基萘酚蓝,扩增温度60 ℃,扩增时间60 min。在可视化LAMP体系中添加两条环引物（LF和LB）反应时间可缩短至20 min。该可视化LAMP反应60 min,其基因组灵敏度可以达到0.010 3 fg/μL,菌落灵敏度可以达到1.9 CFU/mL;利用46 株金黄色葡萄球菌和24 株非金黄色葡萄球菌证实该可视化LAMP具有良好的特异性和可靠性。本研究中建立的可视化LAMP可为金黄色葡萄球菌的快速检测提供一种新的技术。     

兰炭尾气经济高效发电技术方案分析

结合某兰炭生产公司的具体情况,分析了兰炭尾气高温超高压锅炉发电、内燃机发电、燃气-蒸汽联合循环发电的技术经济特点,并对各发电方案的适用性进行了简单阐述,为类似节能改造项目提供参考。     

Fe3O4/δ-MnO2纳米片的制备及其对 亚甲基蓝的吸附研究

采用拓扑氧化法制备δ-二氧化锰六边形纳米片,通过共沉淀法控制pH=10,使Fe2+与Fe3+发生共沉淀形成四氧化三铁沉积于δ-二氧化锰纳米片表面,形成Fe3O4/δ-MnO2磁性六边形纳米片。研究了铁用量对Fe3O4/δ-MnO2结构和晶相的影响。利用X射线衍射（XRD）、场发射扫描电子显微镜（FESEM）等技术手段对其进行表征分析。研究了Fe3O4/δ-MnO2磁性纳米片对亚甲基蓝溶液的吸附行为,系统分析了吸附剂用量、亚甲基蓝初始浓度和吸附时间对吸附效率的影响。Fe3O4/δ-MnO2六边形纳米片尺寸大小均一,边长约为100 nm。该材料对亚甲基蓝表现出良好的吸附性能,当吸附时间为1 h时吸附量约为2.7 mg/g,去除率约为86.3%。     

SnWO4/g-C3N4复合光催化剂降解亚甲基蓝溶液

采用溶剂热法制备SnWO_4/g-C_3N_4复合光催化剂,在可见光降解亚甲基蓝实验中研究复合催化剂的光催化性能。考察催化剂投加量、亚甲基蓝溶液初始浓度、溶液pH值、盐效应对光催化性能的影响及SnWO_4/g-C_3N_4复合光催化剂的重复利用性。实验结果表明,在催化剂投加量1.0 g·L~(-1)、亚甲基蓝溶液初始浓度15 mg·L~(-1)和溶液pH值7.08时,在可见光条件下反应3 h,亚甲基蓝溶液脱色率达到94.2%;NaCl对光催化降解亚甲基蓝具有抑制作用,加入10 mmol·L~(-1)的NaCl溶液后亚甲基蓝的脱色率降为76.0%;复合光催化剂循环使用5次后,暗吸附后光照3 h,亚甲基蓝溶液的总脱色率仍可达到78.7%,重复利用性良好。     

ZSM-5分子筛形貌及硅铝比对甲缩醛气相羰基化反应性能的影响

通过调控合成方式、改变原料比例,制备纳米棒状、纳米球状、椭球状、圆柱状及棋子状等不同形貌及硅铝比的ZSM-5分子筛,并对其催化甲缩醛气相羰基化反应性能进行详细考察。在110℃、0.6 MPa、CO与甲缩醛流速分别为100 mL·min-1和0.035 mL·min-1条件下,硅铝物质的量比为30的棋子形ZSM-5分子筛表现出最佳的催化活性,甲缩醛转化率达31.9%,目标产物甲氧基乙酸甲脂选择性为21.4%。通过XRD、SEM、XRF、Py-FTIR、NH 3-TPD以及27 Al MAS NMR等对合成的分子筛进行详细表征,发现调控分子筛形貌及硅铝物质的量比可改变ZSM-5分子筛的酸性特征,并改变分子筛骨架中活性铝物种分布。适量的中强B酸酸位及分子筛交叉孔道内较高比例的活性铝物种分布可能是硅铝物质的量比30的棋子形ZSM-5分子筛表现出较好催化活性的原因。     

Fe掺杂WO_3催化剂制备及催化降解染料性能

以钨酸钠、硝酸铁为原料,采用水热法制备WO_3和铁掺杂WO_3(Fe-WO_3)固体催化剂。通过红外光谱(FT-IR)、X射线多晶衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)及固体紫外-可见漫反射等表征催化剂。结果表明,制备的Fe-WO_3样品粒子呈片状,厚度达到纳米级。Fe掺杂WO_3的晶体结构受焙烧温度的影响,400℃焙烧得到的四方晶型样品具有较高的催化活性。固体紫外-可见漫反射表明,与WO_3相比,Fe掺杂WO_3发生红移,增强了可见光下的催化活性。以Fe-WO_3为催化剂降解亚甲基蓝,当亚甲基蓝初始浓度为10 mg·L^(-1),pH=11,催化剂用量1 g·L^(-1),质量分数30%的H_2O_2用量2.5 mL·100 mL^(-1),反应时间100 min时,亚甲基蓝降解率可达95.56%。     

甲基丙烯酸甲酯的电化学乳液聚合

采用可编程的线性直流电源电解铁阳极产生Fe2+,以此引发过硫酸铵（APS）产生自由基,催化甲基丙烯酸甲酯（MMA）单体进行乳液聚合。在优化的聚合时间和引发剂浓度条件下,重点研究了电流强度对聚合物相对分子质量及分布的调控作用。结果表明：在0.10~0.18 A的电流范围内,随着电流强度的增大,聚合物的平均相对分子质量也有所增加。通过调节电流的大小,可以对聚合物的相对分子质量分布进行调控,当电流从0.10 A增大至0.12 A时,聚甲基丙烯酸甲酯（PMMA）相对分子质量分布指数（Mw/Mn）减小为1.461。