近红外光谱法测定茶多酚中总儿茶素含量

以高效液相色谱(HPLC)分析结果为参考值,建立了快速测量茶多酚中总儿茶素含量的近红外光谱定标模型.将48份茶多酚样品组成定标样品集,在1000～2500nm(4000～10000cm-1)的近红外漫反射光谱为定标波长范围内,光谱经一阶导数(Firstderivative)、二阶导数(Secondderivative)、标准归一化(Stan-dardnormalvariate,SNV)和多元散射校正(multiplicativesignalcorrection,MSC)处理后结合偏最小二乘回归(PLS)定标.经内部交叉验证表明,光谱经SNV处理后建模结果最佳.模型的相关系数Corr.Coeff=0.997,校正均方根RMSEC=1.71%.比较了经典最小二乘法(CLS)、偏最小二乘法(PLS)和主成分回归(PCR)等方法建模结果,以偏最小二乘回归建模效果最好.     

均匀设计方法优选活性污泥降解2，6-DNT条件的研究

以2,6-DNT做为唯一碳氮源,对活性污泥进行驯化。采用GC-ECD对降解后的2,6-DNT进行含量测定,应用U9（94）均匀设计法以降解率为指标,考察PH值、温度、需氧量（摇床转速）及底物浓度对其的影响,并进行二项式逐步回归处理,优选出最佳的试验条件。在该降解条件下,PH值7．3,温度29℃,转速129r／min,底物浓度135mg／L,验证结果与均匀设计实验预测结果接近,说明均匀设计是优化多因素多水平实验的有力工具。     

虫草粉中铅含量的测定

为了确立高效、准确的虫草粉中铅含量的测定方法,采用湿式消解法、压力罐消解法和微波消解法对样品进行消化前处理,最后用石墨炉原子吸收光谱法进行测定.对测定结果分析得出3种处理方法,所得结果均在可信区间内,其中湿式消解法回收率低于微波消解和压力罐消解法,湿式消解法和压力罐消解法耗时是微波消解法数倍,因此,微波消解法用于虫草粉...     

均匀试验设计优化金银花总黄酮的提取

本试验采用均匀试验设计法优化金银花中总黄酮提取条件,考查了回流时间、回流温度、提取溶剂乙醇水溶液的比例及提取次数4个因素对金银花中总黄酮提取的影响,以总黄酮的含量为评价指标进行U9(94)试验,确定最佳提取条件。结果表明,总黄酮提取最佳条件为提取时间1h、提取温度85℃、水醇溶剂比例70%、提取次数2次。本研究还进行了超声提取比较实验,为建立的实际工艺的提取方法提供了理论依据。     

高效液相色谱法测定茶叶中儿茶素含量的不确定度评定

建立了效液相色谱法测定测定茶叶中儿茶素质量分数的不确定度评定方法,以及HPLC法定量分析茶叶中儿茶素类物质的数学模型.根据《测量不确定度评定与表示》(JJF 1059-1999)中有关规定评估其不确定度,并推导出不确定度计算公式;通过对公式中各变量的分析,计算了各变量的不确定度,最后计算出合成标准不确定度.     

多巴胺-沙棘枝条粉/聚丙烯酸复合材料的制备及性能研究

以附有多巴胺的废弃沙棘枝条粉(PD-HBP)和丙烯酸(AA)为原料,过硫酸钾(K2S2O8)为引发剂,N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,制备了环境友好型PD-HBP/PAA(聚丙烯酸)高吸水性复合材料。采用红外光谱(FTIR)和场发射电子扫描电镜(FE-SEM)表征产物的结构。考察了盐溶液浓度、离子类型及反复使用次数对PD-HBP/PAA吸水能力的影响。结果表明,PD-HBP/PAA在去离子水、自来水和0.9%(质量分数)NaCl溶液的吸水倍率分别可达251.7g/g、172.0g/g和42.1g/g,吸水性能对盐溶液浓度、离子类型及洗水次数较为敏感。反复吸放液7次后,去离子水和0.9%(质量分数)NaCl溶液的吸水倍率分别保持了最大吸水倍率的73.3%和53.0%。     

牡蛎粉中砷、铅、汞、镉有害金属含量的测定研究

采用微波消解法处理的样品,用原子荧光法来分析测定样品中的痕量Hg,用等离子原子发射光谱法来分析测定样品中As、Pb、Cd的含量。研究了测定不同金属元素的最佳仪器的工作条件,并对方法的准确度和精密度进行考察。结果表明,牡蛎粉中的砷、铅、镉、汞含量分别为9.65μg/g,1.00μg/g,11.1μg/g,0.0511μg/g,加标回收率为89.0%~106.9%,相对标准差为0.50%~4.76%。测定方法简单易行,方便快捷。     

牡蛎粉中砷、铅、汞、镉有害金属含量的测定研究

采用微波消解法处理的样品,用原子荧光法来分析测定样品中的痕量Hg,用等离子原子发射光谱法来分析测定样品中As、Pb、Cd的含量。研究了测定不同金属元素的最佳仪器的工作条件,并对方法的准确度和精密度进行考察。结果表明,牡蛎粉中的砷、铅、镉、汞含量分别为9．65μg／g,1．00μg/g,11．1μg/g,0．0511μg/g,加标回收率为89．0％～106．9％,相对标准差为0．50％～4．76％。测定方法简单易行,方便快捷。     

沙棘籽中原花青素的提取工艺研究

本文以提取沙棘油后的沙棘籽渣作为原料,乙醇为提取液,采用大孔吸附树脂精制法提取沙棘籽原花青素。结果表明采用D3520型大孔树脂,用50％乙醇洗脱提取,温度30℃,料液比1：8（w／v）,连续提取12h（60mkq／次）,原花青素的提取率可达9．84％（以脱脂沙棘千重计）,纯度达39．18％。该方法对沙棘籽渣中原花青素具有良好的精制效果。     

基于均匀设计的MEMS陀螺温度标定试验设计

针对传统的温度试验方案存在试验量大、耗费时间长的问题,提出基于均匀设计法的三轴微电子机械系统(micro-electromechanical systems,MEMS)陀螺温度标定误差补偿试验方案。设计基于均匀设计的四因素(测试温度点、温变速率、MEMS陀螺转速及转动方向)试验方案。首先,构造试验所需的均匀设计表;其次,根据LP-偏差确定MEMS陀螺温度标定误差补偿实验的最佳试验方案;最后,搭建出MEMS陀螺温度标定的实验装置进行测试。试验结果表明:与将每一个因素的不同水平组合的全面设计方案相比,该试验方案不仅节省12.5%的试验时间,还进一步减少MEMS陀螺温度标定误差试验量,缩短研究周期,节约试验成本。     

绿茶胶囊对黑巧克力中表儿茶素和儿茶素在人体内生物利用率的影响

以志愿者体内实验方式考察绿茶胶囊对黑巧克力中表儿茶素和儿茶素在人体内生物利用率的影响.六位志愿者在实验前一天严格执行低黄酮类饮食,空腹过夜并留下尿样作为空白样本.试验第一阶段:志愿者摄入50g黑巧克力(含表儿茶素152mg,儿茶素33mg).一周之后的第二阶段,志愿者摄入50g黑巧克力和一片绿茶胶囊(绿茶胶囊含表儿茶素207mg,儿茶素39mg).服用后每间隔一定时间,收集志愿者尿样,测定表儿茶素和儿茶素的生物利用率.结果显示,虽然第二阶段的表儿茶素和儿茶素摄入总量均高于第一阶段,但两者在第一阶段人体中的生物利用率均高于第二阶段.因此和单独摄入黑巧克力相比,绿茶胶囊和黑巧克力同时服用可能会导致减少或者延迟人体对表儿茶素和儿茶素的吸收.     

基于均匀设计方法研究不锈钢焊条的脱渣性

为了定量地分析药皮辅料对焊条工艺性能的影响,利用中国数学会均匀设计分会推荐的UST4.0软件安排配方试验并处理数据,研究了不锈钢焊条的脱渣性.试验中,将10种辅料怍为自变量,焊缝的脱渣性作为目标函数.通过数理统计给出了每种药皮辅料影响焊缝脱渣性的趋势图,并建立了10种药皮辅料及其交互作用对应干脱渣性的数学模型.研究表明:金红石、钛白粉、电解锰、钛铁和白泥对焊缝脱渣性的影响都为正相关;冰晶石和萤石对焊缝脱渣性的影响为负相关;绝大多数药皮辅料对焊缝脱渣性的影响呈交互作用的形式.     

基于均匀设计及非线性偏最小二乘法的非闭合电极ECT传感器参数优化设计

提出了一种非闭合电极电容层析成像(ECT)传感器结构参数的优化方法.采用均匀设计结合非线性偏最小二乘(NPLS)回归,提取传感器结构参数(电极极板的宽度 L、绝缘外壳的壁厚δ1.、屏蔽罩与绝缘外壳间距δ2及绝缘外壳材料的相对介电常数ε)与待优化指标(敏感场的均匀度及灵敏度指标p1、最大与最小电容的比值 K)间的函数关系,建立相应的优化目标泛函,通过对优化目标泛函的求解,最终获得传感器结构参数的最优值.并以 10 电极非闭合电极 ECT 传感器为研究对象,进行了结构参数的优化设计,根据优化结果设计制作了非闭合电极 ECT 传感器,对其成像进行了仿真与实测.结果表明,参数优化后的传感器图像重建质量优于未优化的传感器.     

Response surface method based on uniform design and weighted least squares for non-probabilistic reliability analysis

The non-probabilistic reliability theory is a promising methodology for implementing structural reliability analysis in case of scarce statistical data. One of the main obstacles to implement non-probabilistic reliability analysis is the implication of the limit state function (LSF) for complex structures. This paper aims to establish a surrogate model of the LSF with higher simulation precision, and whereby proposes a response surface method based on the combination of uniform design (UD) and weighted least squares (WLS). At first, the UD method is selected as the sampling method of interval variables to realize the uniform space-filling of the initial samples, and the sample set is updated by gradually adding the approximate optimal points to increase the sampling density of critical domain. Then, the WLS method is applied to improve the precision of the response surface by adjusting the importance of samples to the function fitting. Finally, a method of constructing sample weights is developed. Two examples are applied to validate the feasibility and efficiency of the proposed method. Results show that the proposed method is effective for non-probabilistic reliability analysis of complex structures owning to high computational precision and low computational cost in both numerical and case study.     

婴幼儿配方食品和乳粉中维生素B2的测定

采用高效液相-二极管阵列检测器检测婴幼儿配方食品和乳粉中核黄素(维生素B2),样品在稀盐酸环境中高温水解、酶解,经C18反相色谱柱分离,流动相为乙酸钠(pH=4.5)-甲醇(体积比为65∶35),检测波长为450nm。本方法中维生素B2线性范围为0~26.5μg/mL,检出限为0.02μg/mL。维生素B2平均加标回收率为94.0%,维生素B2相对标准偏差为0.44%,合成标准不确定度为4.917×10-3。该方法简单、快速、测定干扰小,结果与国家标准测定方法比较无显著性差异。     

Prediction of mechanical properties of polypropylene/waste ground rubber tire powder treated by bitumen composites via uniform design and artificial neural networks

Polypropylene (PP)/waste ground rubber tire powder (WGRT) composites were studied with respect to the effect of bitumen and maleic anhydride-grafted styrene–ethylene–butylene–styrene (SEBS-g-MA) content by using the design of experiments (DOE) approach, whereby the effect of the four polymers content on the final mechanical properties were predicted. Uniform design method was especially adopted for its advantages. Optimization was done using hybrid artificial neural network–genetic algorithm (ANN–GA) technique. The results indicated that the composites showed fairly good ductibility provided that it had a relatively higher concentration of bitumen and SEBS-g-MA under the studied condition. A quantitative relationship was presented between the material concentration and the mechanical properties as a set of contour plots, which were confirmed experimentally by testing the optimum ratio.     

Dry powder inhaler of colistimethate sodium for lung infections in cystic fibrosis: optimization of powder construction

Abstract

Colistimethate sodium (CMS) for treatment of lung infections in cystic fibrosis patient was transformed into a dry powder for inhalation by spray drying. Design of Experiment was applied for understanding the role of the spray-drying process parameters on the critical quality attributes of the CMS spray-dried (SD) powders and agglomerates thereof. Eleven experimental SD microparticle powders were constructed under different process conditions according to a central composite design. The SD microparticles were then agglomerated in soft pellets. Eleven physico-chemical characteristics of SD CMS microparticle powders or agglomerates thereof were selected as critical quality attributes. The yield of SD process was higher than 75%. The emitted fraction of agglomerates from RS01 inhaler was 75–84%, and the fine particle fraction (particles <5?µm) was between 58% and 62%. The quality attributes of CMS SD powders and respective agglomerates that were significantly influenced by spray-drying process parameters were residual solvent and drug content of the SD microparticles as well as bulk density and respirable dose of the agglomerates. These attributes were also affected by the combination of the process variables. The air aspiration rate was found as the most positively influential on drug and solvent content and respirable dose. The residual solvent content significantly influenced the powder bulk properties and aerodynamic behavior of the agglomerates, i.e. quality attributes that govern drug metering in the device and the particles lungs deposition. Agglomerates of CMS SD microparticles, in combination with RS01?DPI, showed satisfactory results in terms of dose emitted and fine particle fraction.     

配方奶粉中核苷酸含量高效液相色谱测定

研究建立了定量测定配方奶粉中5种核苷一磷酸(钠盐)的高效液相色谱方法。通过添加适量乙酸、离心浓缩、调节pH等技术方法,快捷有效地去除奶粉中影响核苷酸含量定量测量的蛋白质、脂肪及其他杂质成分,使用核苷酸国家级标准物质,采用外标法对样品中的核苷酸含量进行了定量测量。结果表明:该方法检出限低,准确度在90.8%～99.3%之间,方法的重复性限为1.43,再现性限为2.44。该方法准确度高,重复性好,可行性强,易于掌握,并且快捷、成本低,为奶粉中核苷酸含量的定量测量及相关产品的质量技术监督检验提供了方法学依据。     

Improved mechanical properties of epoxy reinforced by low content nanodiamond powder

Nanodiamond powder (NDP) was dispersed in epoxy resin with low content by means of a high powerful ultrasonic liquid processor and then mixed with curing agent using a high-speed mechanical agitator. The good dispersion of NDP in epoxy could be observed. The mechanical properties of the NDP/epoxy nanocomposites were investigated. It was found that with a NDP content of only 0.3 wt%, the Vicker's hardness, tensile strength and tensile modulus of the NDP/epoxy nanocomposites were 24.7%, 52.7% and 54.2% higher than that of pure epoxy, respectively. The significant improvement of the mechanical properties of the NDP/epoxy nanocomposites could be attributed to the good dispersion of the NDP in the epoxy matrix and grafting of epoxy to NDP by an esterification reaction.     

石墨炉原子吸收法测定螺旋藻粉中的铅和镉

采用微波消解石墨炉原子吸收法测定螺旋藻粉中Pb、Cd。方法的检出限Pb：0．93μg／L,Cd：0．015μg／L,回收率96—108％,RSD小于7．3％。结果表明该方法准确、快速、令人满意。