系统药理学法研究“上火”与氧化应激之间的关系

运用中药系统药理学来分析黄连解毒汤,进而研究"上火"与氧化应激之间的关系.运用系统药理学中的靶点预测和网络药理学部分用来研究黄连解毒汤的抗氧化机制.具体来说,对黄连解毒汤的22个活性组分做靶点预测,发现有38个靶点与之相互作用,其中10个靶点与其抗氧化机制有关.且黄连解毒汤的抗氧化机制在组分水平、靶点水平、靶点对细胞因子水平上都有体现.从药理学角度,黄连解毒汤的抗氧化作用显著,与其在中药中强大的"清火"功能相对照后,就可以看出"上火"与氧化应激密切相关.将系统药理学应用于中药的方法,为"上火"的研究提供了一条新的思路.     

奶粉中三聚氰胺等伪蛋白的危害和新检测方法

2008年9月,中国爆发了“三鹿”婴幼儿奶粉受污染事件,导致不少食用受污染奶粉的婴幼儿产生肾结石病症,甚至引发了危及生命的严重并发症。国家质检总局对此事进行了系统的调查,结果表明,事件的主要原因在于奶粉中含有三聚氰胺,长期食用这些高含量三聚氰胺的奶粉危害了婴幼儿的健康,这就是震惊中外的“三聚氰胺事件”。     

使用"空白对比法"测量吸光度原理的一种简单解释

在分析化学、仪器分析及吸收光谱法专著中,关于吸光度测量都讲到,为了校正测量中溶剂的吸收、容器的吸收、光的散射和界面反射等因素的影响,必须采用“空白对比法”.但为什么采用“空白对比法”就能校正上述因素的影响,却未讲清楚,故有作探讨的必要. 按吸光度定义的要求,通过试液光强的减弱应该只与被测物(吸光物)有关,即     

高效液相色谱-串联质谱法对奶粉、酸奶中全氟化合物的分析

建立了液相色谱-质谱检测奶粉和酸奶中11种全氟化合物(PFCs)的分析方法.分别考察了溶液离子强度和酸碱度对固相萃取效率的影响,结果表明,0.5 ～12.5 mmol/L NaCl溶液的影响很小,且中性和微酸性条件下回收率较好.通过优化和比较,选用等体积的甲醇和0.01 mol/L盐酸的甲醇溶液依次对奶粉中的PFCs进行萃取,对于酸奶则使用甲醇直接萃取,并用WAX柱对萃取液净化.以甲醇(A)和50 mmol/L 醋酸铵(B)为流动相进行梯度洗脱,洗脱时间为10 min(或15 min),流速1 mL/min.内标法定量,奶粉和酸奶中11种PFCs的加标回收率分别为81% ～111%和80% ～118%,方法检出限为2 ～29 ng/L.用该方法对市售国产和进口奶粉及酸奶样品中的PFCs进行了分析.     

摩擦化学过程及其模型

本文介绍了与工程技术特别是高技术关系密切的摩擦化学过程.对比了力学激励和热激励所导致的化学反应的差别.介绍了摩擦化学这一学科的形成和定义,研究对象及常用方法.对目前比较流行的“热点”模型和“变形”模型的根据和物理实质及各自的缺点做了阐述和分析.     

具有核酸分子"光开关"特性钌(Ⅱ)配合物的研究进展

钌（Ⅱ）配合物类核酸分子“光开关”探针性质稳定、无毒环保,可用于痕量核酸检测、基因序列分析及三链DNA检测、DNA图像研究及DNA动力学过程分析、基因损伤研究、基因转染材料研究、量子点生物效应研究及用作电化学探针。随着核酸及其相关分析研究的不断深入和适配子技术的迅猛发展,基于核酸和核酸分子“光开关”还可进行药物筛选、生命活性分子如ATP及蛋白质等的分析检测,具有简便、快速、灵敏、抗光漂白等特性。对生命科学基础研究、食品安全及医学诊断具有重要的理论意义。作者对近10年来核酸分子“光开关”探针研究进展进行了评述,引用文献55篇。     

"你眼中的化学课"教育调查报告

1　问卷调查清华附中实习期间 ,在与学生广泛接触的同时 ,我们体察到了学生学习化学的种种态度和情况。为进一步深入了解 ,我们进行了一次题为“你眼中的化学课”(问卷见附页 )的问卷调查 ,旨在考察目前学生学习化学的兴趣和具体感受 ,争取能对化学课程的编排和教学活动提供一定参考。问卷调查在清华附中高一、高二 2个年级共 8个班以无记名的方式进行 ,发放问卷 170份 ,学生当场答卷 ,共回收问卷 15 4份。2　调查结果及分析2 .1　问卷前 3题数据统计及分析1.你认为相对其他理科基础课程 (如 :数学、物理等 ) ,化学的重要性如何 (　　 )Ａ .…     

反相高效液相色谱法测定强化奶粉中β-胡萝卜素含量

采用碱皂化石油醚提取,Kromasil C18柱分离,以甲醇∶氯仿=75∶25等度淋洗,二极管阵列检测器检测,测定了强化奶粉中β-胡萝卜素含量.对最佳皂化用碱量、皂化时间、α、β-胡罗卜素及β-胡罗卜素异构体分离条件进行了探索.该方法回收率为91.6%~96.3%,其标准偏差、变异系数分别为1.64%及1.76%.方法简便、快速,精密度及准确度在允许范围内,适用于奶粉中β-胡罗卜素的测定.     

辨别猪肉是否有“瘦肉精”方法

不久前,教育部组织专家对中国农业大学完成的“乳品真蛋白检测技术研究与方法筛选”项目进行了成果鉴定。2008年“三鹿肾结石奶粉事件”被曝光后,课题组及时推出了可以对乳品中真实的蛋白质含量进行测定的标准：NY／T1678—2008。该标准是迄今国内外与“蛋白质”相关的标准中,唯一不会将三聚氰胺误判为“蛋白质”的标准。     

基于模型建构促进学生“化学反应速率”认识发展的教学研究

基于对“化学反应速率”已有教学研究和对“化学反应速率”概念本体的分析,提出了基于模型建构的“化学反应速率”的教学策略,构建了“化学反应速率”的认识模型及不同教学阶段的层级发展模型,并深入分析了“化学反应速率”对促进学生认识发展的功能价值.在理论分析和探讨的基础上,运用设计性研究和对比性教学实验进行了教学设计及实施研究,通过问卷调查、学生访谈等方法对教学效果进行了检验,总结出本研究的结论和启示.     

"Early" protein synthesis of Lactobacillus delbrueckii ssp. bulgaricus in milk revealed by [35S] methionine labeling and two-dimensional gel electrophoresis

The proteomes of exponentially growing and stationary cells of Lactobacillus delbrueckii ssp. bulgaricus grown in rich medium (MRS) were separated by two-dimensional polyacrylamide gel electrophoresis (2-DE) and quantified after Coomassie staining. Stationary cells grown in MRS were inoculated in reconstituted skim milk, and "early" protein synthesis during the first 30 min of fermentation in milk was monitored by [35S]methionine labeling and 2-DE. In contrast to exponentially growing or stationary cells, the predominant "early" proteins were small (< 15 kDa) and of low pI (< 5.3). Quantification of the proteome of the "early" lag phase based on 47 "spots" revealed that only three "early" proteins accounted for more than 80% of the total label. They were identified as pI 4.7 and 4.9 isoforms of the heat-stable phosphoryl carrier protein (HPr) with 45.2 and 9.4% of total label, respectively, and an unknown protein called EPr1 ("early" protein 1) with 26.6% of total label. Although an N-terminal sequence of 19 amino acids was obtained, no homologs to EPr1 could be found. De novo synthesis of the 10 and 60 kDa heat shock proteins (GroES and GroEL) was considerably lower (0.04 and 0.9% of total label, respectively), indicating only low levels of stress. Synthesis of triosephosphate isomerase (Tpi) as marker for glycolytic enzymes reached only 0.08% of total label. Our results demonstrate that inoculation in milk, resulting in a change from glucose to lactose as carbon source, imposes only little need for synthesis of stress or glycolytic enzymes, as sufficient proteins are present in the stationary, MRS-grown cells. The high level of expression of the pI 4.7 isoform of HPr suggests a regulatory function of the presumed Ser-46 phosphorylated form of HPr.     

Death kinetics of <Emphasis Type="Italic">Escherichia coli</Emphasis> in goat milk and <Emphasis Type="Italic">Bacillus licheniformis</Emphasis> in cloudberry jam treated by ohmic heating

The influence of ohmic heating on the death kinetic parameters of Escherichia coli ATCC® 25922 in goat milk and spores of Bacillus licheniformis ATCC® 14580 in cloudberry jam was investigated and compared with that of conventional heating. Ohmic treatment of goat milk shortened the decimal reduction time D in comparison with the D values obtained at conventional treatment. Similarly, the z value, increase of temperature required for a ten-fold reduction of D, was also lower at ohmic treatment. The death kinetics of Bacillus licheniformis ATCC® 14580 spores in cloudberry jam was also studied employing both types of heat treatment. Similar conclusions were obtained for the D values as in the case of goat milk. However, the differences between the z values obtained for ohmic and conventional heating were not significant.     

锌宝冲剂的研制、临床应用及微量元素锌的测定

以新鲜功托性保健锌蛋为原料．辅以鲜牛奶、大豆、蔗糖等配料,经不减损鸡蛋原有营养成分的科学方法加工成锌宝冲剂．经初步临床观察．本品是临床和日常饮食补充微量元素锌的保健珍品,并选用原子吸收分光光度法测定了本品微量元素锌的含量．     

Determination of total selenium and selenium distribution in the milk phases in commercial cow’s milk by HG-AAS

A procedure has been developed for determining the selenium in cows milk using hydride generation–atomic absorption spectrometry (HG-AAS) following microwave-assisted acid digestion. The selenium distributions in milk whey, fat and micellar casein phases were studied after separating the different phases by ultracentrifugation and determining the selenium in all of them. The detection limits obtained by HG-AAS for the whole milk, milk whey and micellar casein were 0.074, 0.065 and 0.075 g l^–1, respectively. The accuracy for the whole milk was checked by using a Certified Reference Material CRM 8435 whole milk powder from NIST, and the analytical recoveries for the milk whey and casein micelles were 100.9 and 96.9%, respectively. A mass balance study of the determination of selenium in the different milk phases was carried out, obtaining values of 95.5–100.8%. The total content of selenium was determined in 37 milk samples from 15 different manufacturers, 19 whole milk samples and 18 skimmed milk samples. The selenium levels found were within the 8.5–21 g l^–1 range. The selenium distributions in the different milk phases were studied in 14 whole milk samples, and the highest selenium levels were found in milk whey (47.2–73.6%), while the lowest level was found for the fat phase (4.8–16.2%). A strong correlation was found between the selenium levels in whole milk and the selenium levels in the milk components.     

Rapid analysis of aflatoxin M1 in milk using dispersive liquid–liquid microextraction coupled with ultrahigh pressure liquid chromatography tandem mass spectrometry

A simple, rapid, and sensitive method based on simultaneous protein precipitation and extraction of aflatoxin M₁ (AFM₁) followed by dispersive liquid–liquid microextraction (DLLME) and ultrahigh pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) analysis was developed for the determination of AFM₁ in milk samples. In order to precipitate the proteins and extract AFM₁ from milk, a sample pretreatment using acetonitrile and NaCl as the extraction/denaturant solvent and salting-out agent, respectively, was optimised. Subsequently, the acetonitrile (upper) phase, containing AFM₁, was used as the disperser solvent in DLLME, and extractant (chloroform) and water were added in turn to the extract to perform the DLLME process. The main parameters affecting the extraction efficiency of the whole analytical procedure, such as acetonitrile volume, amount of salt, type and volume of extractant and water volume, were carefully optimised by experimental design. Under optimum conditions, the developed method provides an enrichment factor of 33 and detection and quantification limits (0.6 and 2.0 ng kg^?1, respectively) below the maximum levels imposed by current regulations for AFM₁ in milk and infant milk formulae. Recoveries (61.3–75.3 %) and repeatability (RSD?<?10, n?=?3), tested in different types of milk at four AFM₁ levels, met the performance criteria required by EC Regulation No. 401/2006. Moreover, the matrix effect on the signal intensity of the analyte was negligible. The proposed method provides a rapid extraction and an accurate determination of AFM₁ in milk and formula milk using a simple and inexpensive sample preparation procedure.

傅里叶变换红外光谱法分析乳制品的成分

利用甲醇沉淀进口奶粉、国产奶粉和奶茶粉水溶液中的蛋白质,所得上清液用二氯甲烷萃取,再经傅里叶变换红外光谱法(FT-IR)分析沉淀物和各相中物质的成分.试验结果表明:3种样品沉淀物中均含有蛋白质和脂肪酸甘油三酯,在萃取时均有乳糖析出.三者上层(水+甲醇)均含有糊精;而下层(二氯甲烷-甲醇)进口奶粉中含有磷脂酰胆碱,国产奶粉中含有磷脂酰胆碱和长碳链伯酰胺,奶茶粉中含有咖啡因.     

石墨多壳层形成物的离壳生长现象

用高分辨透射电子显微镜(HRTEM)表征了在特定电弧放电条件下(碳阴极,钯管阳极)产生的石墨多壳层结构。看到了各种各样的,由多层石墨壳组成,大小从约2nm到20nm以上的多面体。对它们当中一些多面体所表现出来的自组装(self-assembly)"离壳生长"(out-of-shellgrowth)现象作了鉴定,并对其生长机制进行了讨论。     

Determination of Mineral Elements in Milk Products by Inductively Coupled Plasma-Optical Emission Spectrometry

The determination of mineral elements in milk products is of great importance since their excess or deficiency may affect human health. In this study, calcium, magnesium, potassium, sodium, phosphorus, and iron were determined in milk products from South Korea. The samples were wet-digested by microwave-assisted combustion using nitric acid and hydrogen peroxide, and analyzed by inductively coupled plasma-optical emission spectrometry. The method was validated by sensitivity, linearity, precision, recovery checks, and the analysis of a milk powder certified reference material. The elemental concentrations were similar in the milk products. Calcium and potassium were the most abundant, followed by phosphorus, sodium, magnesium, and iron. All concentrations were comparable to previous values and were within the limits of recommended dietary allowances and tolerable upper levels.     

笼形聚偕氨肟树脂吸附溴和碘

用酸、碱处理的笼形聚偕氨肟树脂（ACAO、BCAO）吸附溴和碘,发现它们的吸附能力无显著差别。吸附客量与溴和碘浓度关系符合Freundlich方程．从扫描电子显微镜观察到碘在树脂表面形成微晶．联系到溴和碘的超当量吸附现象,初步认为,它们是通过物理吸附在树脂表面富集。