The Saint-Venant problem of plane bar under an axial force

I.PrefaceAsweknow,theSaint-Venanttheoryisawell-knownanduniversallyacceptedtheory.Butasoneofthegeneraltheoriesofelasticmechanics,itisnotprovedperfectely,althoughitistestedbyexperiments.Infact,onlyforthesimplestproblemofelasticity,itisnoteasytofindanalytics…     

O~6-METHYLGUANINE-DNA METHYLTRANSFERASE AND HUMAN CANCER CHEMOTHERAPY

Two kinds of human tumor cell strains having different activity of O~6-methylguanine-DNA methyltransferase (O~6-MT) were transplanted into nude mice. Then the mice were inject-ed intraperitoneally with bifunctional alkylating agent 1--(4--amino--2-methyl--5--pyrimidinyl)methy1-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU). The tumors with low O~6-MTactivity were quickly suppressed or cured. The result suggests that some tumors, if previ-sionally determined with low O~6-MT activity, might be efficiently cured by treatment withACNU. This probably opens a new way for human cancer chemotherapy.     

Interaction between 3-aminopropyltrimethoxysilane and oil palm ash in styrene butadiene rubber compounds using response surface methodology

Oil palm ash (OPA) is available in abundance and is renewable. The effects of a combination of OPA and 3-aminopropyltrimethoxysilane on the properties of styrene butadiene rubber (SBR) compounds based on their mixing ratios were studied using response surface methodology. The cure characteristics and tensile properties were selected as the responses. The significance of these factors and their interactions were analysed using ANOVA. The results showed that the presence of OPA and AMPTES had a significant effect on the properties of SBR compounds, whereby all the responses had R² of above 0.9. This indicates that the regression model is accurate in describing and predicting the pattern of significance for each factor studied. In addition, with the highest level of AMPTES (6 phr) and OPA (80 phr) in the SBR, the tensile strength of the mixture was significantly improved by 151.6% compared to that of gum SBR compound. These findings were further supported by scanning electron microscopy.     

乳腺癌的临床光谱检测

基于激光与生物组织的相互作用原理检测乳腺癌是目前国际研究热点。实验室自行开发研制的近红外乳腺检测仪, 采用780 nm的低频调制激光透照乳房,并在计算机控制下做二维扫描,对侧采用光电倍增管接收透射光信号,将其转化为电信号,实现了对乳腺癌疾病的检测。系统对光强信号采样后进行数据处理和成像,得到近红外光乳腺透照图像。该系统在中国医学科学院肿瘤医院进行了临床试验。共采集了50名患者100多个数据。其中恶性肿瘤患者34例,良性13例,其他3例。近红外诊断结果与患者同期的钼靶检测结果、超声检测结果和病理结果做了对照,正确率达到72.5%,介于超声(77.50%)和钼靶(71.88%)之间。说明近红外方法和所使用的样机对判断乳腺疾病有可行性,为近红外图像方法提供了新的研究思路。     

Parameter identification and synchronization of an uncertain Chen chaotic system via adaptive control

A systematic design process of adaptive synchronization and parameter identification of an uncertain Chen chaotic system is provided.With this new and effective method,parameter identification and synchronization of the Chen system,with all the system parameters unknown,can be achieved simultaneously.Theoretical proof and numerical simulation demonstrate the effectiveness and feasibility of the proposed method.     

分散微固相萃取/超高效液相色谱-高分辨质谱法测定茶叶中高氯酸盐

基于分散微固相萃取(DMSPE)技术,采用超高效液相色谱-高分辨质谱(UHPLC-HRMS)建立了茶叶中高氯酸盐的检测方法。样品采用乙腈提取,以PSA和PCX为吸附填料进行DMSPE净化,采用Poroshell 120 PFP色谱柱(50 mm×2.1 mm,1.9μm)为分析柱,甲醇-1.0%乙酸水溶液作为流动相进行梯度洗脱,内标法定量。采用负离子采集模式,靶向单一离子监测(TSIM)/数据依赖质谱(ddMS2)扫描模式进行定性筛查和定量分析。高氯酸盐在0.05~50μg/L范围内线性关系良好(r2=0.9997),方法检出限(LOD)为0.4μg/kg,定量下限(LOQ)为1.2μg/kg;在1.2、12、120μg/kg 3种加标水平下,高氯酸盐在茶叶中的平均回收率为87.4%~105%,日内相对标准偏差(RSD_r)为0.30%~6.1%,日间相对标准偏差(RSD_R)为4.2%~9.2%。该方法操作简单、成本低、样品净化效果好,灵敏度可满足欧盟的残留限量要求,适用于茶叶中高氯酸盐的检测,为我国茶叶中高氯酸盐的监测和风险评估提供了可靠的技术手段。     

液液萃取-高分辨气相色谱-高分辨双聚焦磁质谱法测定尿中羟基多环芳烃代谢物

建立了灵敏、准确的液液萃取-高分辨气相色谱-高分辨双聚焦磁质谱（LLC-HRGC-HRMS）同时测定人体尿样中8种多环芳烃（PAHs）代谢物的方法。将2 mL尿液与氘或¹³C标记的同位素内标物进行混合,在抗坏血酸的存在下酶解偶联目标物,再将游离化合物用甲苯-戊烷（1：4,v/v）萃取后浓缩至近干,再用甲苯复溶,衍生后经HRGC-HRMS分离和测定。1-羟基萘在0.14~41.6 μg/L、1-羟基菲在0.05~8.33 μg/L、2-羟基菲在0.04~8.33 μg/L、其他5种代谢产物在0.02~8.33 μg/L范围内线性关系良好,相关系数＞0.99,方法的检出限为0.006~0.042 μg/L,平均回收率为81.4%~127.0%,日内和日间精密度分别为2.7%~6.9%和5.1%~10.9%（n=6）。应用该方法测定330份人群尿液样本,3-羟基䓛和6-羟基䓛未检出,其他6种PAHs代谢物检出率为100%。该方法灵敏、准确、稳定,适用于人尿中8种PAHs代谢物的定量分析。     

液相色谱-三级质谱法分析尿液中β2-受体激动剂及β-受体阻断剂多组分残留

建立了SPE柱净化结合液相色谱-三级质谱测定尿液中12种β-受体激动剂和4种β-受体阻断剂的方法.尿液样品经冷冻离心,加人β-葡萄糖苷酸酶酶解后,以高氯酸沉淀蛋白,经HLB和MCX固相萃取柱净化.在Waters Atlantis(R)T3色谱柱上以甲醇和含0.1%甲酸流动相进行梯度洗脱分离,采用ESI源正离子模式进行三...