不同结晶度高岭石的带电性研究

本文采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)和热分析(TG-DSC)等三种表征手段,对四个不同地区高岭石样品的结构特征进行了研究.结果表明,高岭石结晶度高低顺序为:淮北>大同>龙岩>清远,Hinckley结晶度指数与脱羟基温度具有较好的相关性.利用电泳仪测定了高岭石颗粒在不同pH条件下的表面电位,并且通过线性拟合pH值-电位图得到了不同结晶度高岭石的零电荷点(PZC).进一步研究得出4种高岭石具有相近的PZC,其范围为3.2～4.3.在pH=7条件下,高岭石的表面电位与Hinckley结晶度指数呈现正相关,而PZC受结晶度指数的影响不强烈.     

分子印迹技术在黄曲霉毒素检测中的最新研究进展EI北大核心CSCD

黄曲霉毒素(AFT)是由黄曲霉和寄生曲霉等某些菌株产生的一类真菌毒素,主要包括B1,B2,G1,G2,M1,M2,GM,P1,Q1,毒醇等,其中B1的毒性最大,致癌性最强,其广泛存在土壤、动植物、各种坚果、谷物,奶,食用油及其制品中,因此,食品中超痕量及痕量的黄曲霉毒素的检测方法受到高度关注。由于农产品样品基质复杂,而黄曲霉毒素含量和限量极低,高效特异性样品前处理技术是高灵敏精准检测黄曲霉毒素的关键之重。近年来分子印迹技术在样品前处理和核心识别元件等方面发展迅猛,在黄曲霉毒素痕量检测方面凸显出一定优势。综述了近几年来分子印迹技术在黄曲霉毒素前处理及快速检测等方面最新研究进展,并展望了分子印迹技术在黄曲霉检测应用的发展前景。     

气相色谱－三重四极杆质谱法测定动物源性食品中砜吡草唑残留量

建立了动物源性食品中砜吡草唑残留量的气相色谱－三重四极杆质谱检测方法。猪肉、猪肝、鸡肉、鸡肝、牛奶和鸡蛋中的砜吡草唑用乙腈提取,经乙二胺-N-丙基硅烷化硅胶、十八烷基键合硅胶和无水硫酸镁去除杂质,离心后取上清液氮吹至干,加入丙酮复溶、过滤后经气相色谱－三重四极杆质谱检测,外标法定量。通过对仪器条件、提取溶剂和净化方式等进行优化,确定最合适的前处理方法和仪器条件。对样品的基质效应进行考察,发现6种基质中砜吡草唑的基质效应均小于20%,为弱基质效应,无需采取补偿措施。在优化实验条件下,砜吡草唑在0.5 ~ 100 μg/L范围内线性关系良好,相关系数为0.999 5。空白样品在4个加标水平下的平均回收率为85.8% ~ 106%,相对标准偏差（n = 6）为3.1% ~ 6.8%,方法定量下限为0.001 mg/kg。采用该方法对50个动物源性食品进行测定,在1个牛肉样品和1个羊肉样品中检出砜吡草唑。该方法操作简单、灵敏度高、准确性好,适用于动物源性食品中砜吡草唑的检测,可为砜吡草唑在动物源性食品中的风险监控提供技术支撑。     

A high-precision multi-channel TAC and QAC module for the neutron detection wall

A single width NIM module that includes eight channels of the time-to-amplitude converter(TAC) and the charge-to-amplitude converter(QAC) is introduced in the paper, which is designed for the large neutron wall detector to measure charge(energy) and time interval simultaneously. The module adopts a high precision gated integration circuit to realize TAC and QAC. The input range of TAC is from 30 ns to 1 μs, and the input range of QAC is from 40 p C to 600 p C. The linearity error of TAC is lower than 1.28%, and the time resolution of TAC is less than 0.871%. The linearity error of QAC is lower than 0.81%, and the resolution of QAC is better than 0.936%.     

药对白术-茅苍术及其单味药中挥发油成分的比较分析

采用水蒸气蒸馏法提取单味药白术、茅苍术及其药对中挥发油成分,通过气-质联用技术(GC-MS)对其分离检测,利用直观推导式演进特征投影法(HELP)分辨解析重叠色谱峰,并结合程序升温保留指数辅助定性.从白术、茅苍术及其药对中依次鉴定出29,50,62个组分,分别占各自挥发油总量的95.93%, 97 44%, 97.47%;其中20种挥发油成分共存于单味药与药对中,主要是2-(2-甲氧基)苯甲氧基苯酚、γ-芹子烯、雅槛蓝树油烯、大根香叶烯B等.组成药对后,白术减少8种组分,茅苍术减少12种组分,而药对新增22种组分,主要是单萜烯类的低沸点化合物,新增组分在药对中的作用不容忽视.     

Quality evaluation of Ganoderma through simultaneous determination of nine triterpenes and sterols using pressurized liquid extraction and high performance liquid chromatography

A method combining HPLC and pressurized liquid extraction was developed for simultaneous quantification of nine components, including eight triterpenes (ganoderic acid A, ganoderic acid Y, ganoderic acid DM, ganoderol A, ganoderol B, ganoderal A, methyl ganoderate D and ganoderate G) and a sterol (ergosterol), in Ganoderma. The determination was achieved by using a Zorbax ODS C18 analytical column (4.6 x 250 mm id, 5 microm) and gradient elution with diode-array detection. All calibration curves showed good linearity (r2 > 0.9997) within the test ranges. The developed method showed good repeatability for the quantification of the nine investigated components in Ganoderma with intra- and inter-day variations of less than 2.4% and 4.1%, respectively. The validated method was successfully applied to quantify the nine components in two species of Ganoderma, i.e. G. lucidum and G. sinense, used as Lingzhi in China. Furthermore, hierarchical clustering analysis based on the nine components in HPLC profiles from the tested 11 samples showed that chemical characteristics were significantly different between G. lucidum and G. sinense, which suggested that clinical investigation should be performed so as to ensure the safety and efficacy of medication.     

New-generation biomedical materials:Peptide dendrimers and their application in biomedicine

Peptide dendrimers are attractive synthetic polymers and have been widely used as a new generation of biomaterials in recent years.Peptide dendrimers,as well as general dendrimers,may be synthesized to reach nano sizes,and display well-defined architectures,highly-branched structures,high density of functional terminal groups,and controllable molecular weights.On the other hand,peptide dendrimers have properties similar to proteins and some special characteristics,such as good biocompatibility,water solubil...     

新型生物医用材料: 肽类树枝状大分子及其生物医学应用

肽类树枝状大分子是近年来发展起来的一类新型生物医用高分子材料, 它在具有普通树枝状大分子的特征如规整性、高度支化、表面呈现高密度功能团、尺度为纳米级、通过可控制备可得到单一分子量等之外, 同时还具有类似蛋白一样的球状结构、好的生物相容性、水溶性、耐蛋白酶水解、生物降解等独特的性能. 肽类树枝状大分子的上述特点, 使其在生物医学应用中显示出诱人的前景. 本综述从肽类树枝状大分子的制备出发、详尽介绍了肽类树枝状大分子的功能化及其在疾病诊断和治疗中的应用等方面的研究进展, 籍此推动肽类树枝状大分子在生物医学领域的研究与开发.     

QuEChERS-液相色谱串联质谱法快速检测果蔬中的农药多残留

建立了果蔬样品中氨基甲酸酯类、有机磷类、苯并咪唑类、苯甲酰脲类等各类29种农药多残留的液相色谱-串联质谱检测方法。采用QuEChERS方法进行前处理,样品经1%冰醋酸乙腈提取、醋酸钠和无水硫酸镁盐析后,上清液加入伯仲胺粉、C18粉及石墨化碳黑粉进行分散固相萃取净化。提取液经Waters SunFire C18(5μm,4.6×150 mm)色谱柱分离后,进行LC-MS/MS多反应监测模式下的定性及定量分析。29种农药的检出限在0.005~0.352μg/kg之间,定量限在0.015~1.176μg/kg之间。在1~10μg/kg的3个添加水平范围上,平均回收率在70%~119%之间,RSD小于16%。本方法可用于果蔬样品中农药多残留的确证检测。     

药对青蒿-桂枝中挥发油成分的GC-MS分析与化学计量学解析

采用水蒸气蒸馏法从青蒿、桂枝及其药对中提取挥发油成分,利用气相色谱-质谱(GC-MS)联用技术进行分离检测,通过化学计量学解析法(CRM)对重叠色谱峰解析,并结合程序升温保留指数辅助定性.从药对及其单味药青蒿、桂枝中分别鉴定出69、66、68种挥发油;组成药对后,单味药成分减少,新成分增加,药对与单味药挥发油共存17种组分,它们是cis-细辛醚、丁子香烯、丁子香烯环氧化物等成分,占药对挥发油总含量的35.82%;而药对中挥发油的主要成分是(E)-桂皮醛(18.32%)和cis-细辛醚(10.20%)等,其含量并非单味药含量的简单相加,相关作用机理有待进一步研究.