Effect of the grain size on the macroscopic response of aluminum to shock loading

Shock tests of two lots of a 1420 aluminum-lithium alloy are performed. The mean grain size is 24 μm in the first lot and 1.6 μm in the second lot obtained by the method of equal-channel angular pressing. Two characteristics of dynamic strength of the material were determined in experiments on the high-velocity impact of flat samples: threshold of dynamic stability with respect to compression on the fore front of the compression pulse and spall strength of the material. The materials of both types have an identical threshold of dynamic stability with respect to compression, whereas the spall strength of the microcrystalline alloy is 20% greater than the spall strength of the polycrystalline alloy. The reason is the consumption of energy on structure formation in the coarse-grain material in passing to a larger-scale structural level (in the case with a fine-grain material, such a structure is available in the initial state). The experiments reveal the presence of a second plastic front whose amplitude is approximately 10% of the first plastic front. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 6, pp. 135–146, November–December, 2007.     

Direct analysis of anabolic steroids in urine using Leidenfrost phenomenon assisted thermal desorption-dielectric barrier discharge ionization mass spectrometry

Rapid detection of trace level anabolic steroids in urine is highly desirable to monitor the consumption of performance enhancing anabolic steroids by athletes. The present article describes a novel strategy for identifying the trace anabolic steroids in urine using Leidenfrost phenomenon assisted thermal desorption (LPTD) coupled to dielectric barrier discharge (DBD) ionization mass spectrometry. Using this method the steroid molecules are enriched within a liquid droplet during the thermal desorption process and desorbed all-together at the last moment of droplet evaporation in a short time domain. The desorbed molecules were ionized using a dielectric barrier discharge ion-source in front of the mass spectrometer inlet at open atmosphere. This process facilitates the sensitivity enhancement with several orders of magnitude compared to the thermal desorption at a lower temperature. The limits of detection (LODs) of various steroid molecules were found to be in the range of 0.05–0.1 ng mL⁻¹ for standard solutions and around two orders of magnitude higher for synthetic urine samples. The detection limits of urinary anabolic steroids could be lowered by using a simple and rapid dichloromethane extraction technique. The analytical figures of merit of this technique were evaluated at open atmosphere using suitable internal standards. The technique is simple and rapid for high sensitivity and high throughput screening of anabolic steroids in urine.     

Liquid chromatography tandem mass spectrometry determination of free and conjugated estrogens in breast cancer patients before and after exemestane treatment

We report liquid chromatographic separation with tandem mass spectrometry determination of 12 endogenous estrogens and their intact conjugates in blood and urine and its application to study effects of exemestane treatment on estrogen generation and metabolism in postmenopausal women with estrogen-dependent breast cancer. A 0.5 mL aliquot of each urine or serum sample is fractionated with solid phase extraction to a fraction of free estrogen and another fraction of their conjugates. The reversed phase LC/MS/MS determines dansylated estrogens with positive ionization and intact conjugates with negative ionization. The method provides reproducible separation and limit of detection as low as 1 pg mL⁻¹ for free estrogens and 0.03 ng mg⁻¹ creatinine for the conjugates in serum and urine samples. The method enabled us to acquire unique concentration profiles of 12 endogenous estrogens and their intact conjugates in 30 breast cancer patients before and after one month of exemestane treatment. Exemestane suppressed total serum and urinary estrogens by 11–97% (P < 0.0001) and 8.7–91% (P < 0.0001), respectively. Specifically, these data show that exemestane preferentially suppressed E1, E1-3S, E1-3G, and E2-17G more than other estrogens. Linear regression analysis of estrogen concentrations before and after treatment showed correlation coefficients of 0.8385 (n = 289, P < 0.0001) and 0.8863 (n = 360, P < 0.0001). This study provides urinary and blood estrogen concentration profiles in breast cancer patients to demonstrate the effect of exemestane on estrogen generation, supporting inhibition of aromatase activity.     

固相萃取-高效液相色谱法测定人体尿液中邻苯二甲酸酯及其代谢物

建立了同时测定人体尿液中邻苯二甲酸酯及其代谢物的分析方法.对洗脱剂种类、洗脱体积、洗脱流速等影响因素进行考察,确定了最佳洗脱剂及洗脱体积为2mL乙腈、2mL乙酸乙酯和1mL乙醚-正己烷(1:19,V/V),洗脱流速1mL/min.在最优化的固相萃取-液相色谱条件下测定5种邻苯二甲酸酯及其5种相应的单酯代谢物,线性范围为...     

Element assessment in whole blood, serum and urine of three Italian healthy sub-populations by INAA

This research, that is a framework of a big project regarding the knowledge of human metabolism in patients affected by renal disease, is aimed to assess the levels of some selected essential (Co, Fe, K, Na, Rb, Se and Zn) and non-essential elements (Br Cr, Cs, Hg, Ni and Sb) in different biological matrices such as whole blood, serum and urine, of three Italian sub-populations.The analytical methodology involved is the Instrumental Neutron Activation Analysis (INAA), a primary analytical technique: the samples (totally 144) were irradiated in the Triga nuclear reactor at the R.C.-Casaccia ENEA for 12 h at a neutron flux of 2.6 × 10¹² n × cm^{− 2} × s^{− 1}.The results show a similar distribution for essential elements whereas quite different for non-essential elements. The statistical treatment has evidenced no differences among the samples grouping the subpopulations into unique one. In this way, the levels found can be considered “reference values” in the investigated matrices.     

电感耦合等离子质谱法测定染铅猪仔的血铅、尿铅含量

利用电感耦合等离子质谱法测定染铅猪仔的血铅、尿铅含量.铅元素校正曲线的相关系数达到0.9999,方法检出限为0.08 μg/L.用冻干牛血铅、镉成分分析标准物质和冻干人尿铅成分分析标准物质验证了方法的准确性和重复性,分析结果表明,测定值与标准值基本吻合,测定值的相对标准偏差＜3.4％.用此方法分析了染铅猪仔不同时段的血...     

高效液相色谱-质谱法测定尿液中痕量雷公藤春碱

提出了尿液中雷公藤春碱的高效液相色谱-质谱测定方法。尿液样品经Waters Oasis(MCX固相萃取小柱富集、净化后,以Zorbax Eclipse SB C18反相色谱柱(4.6 mm×250 mm,5μm)为分离柱,以乙酸盐缓冲溶液-乙腈(40+60)为流动相,采用正离子模式大气压化学电离源,在选择离子监测模式下进行检测,雷公藤春碱的定量离子质荷比(m/z)为874.4。线性范围为0.2~50.0μg·L-1,检出限(3S/N)为0.07μg·L-1,测定下限(10S/N)为0.2μg·L-1。回收率在86.0%~92.0%之间,日内(n=6)和日间(n=15)相对标准偏差分别小于7.5%和10.5%。     

Determination of diastereoisomeric alkaloids in urine by capillary electrophoresis with electrochemiluminescence detection

A new and simple capillary electrophoresis with electrochemiluminescence detection was developed for the separation and the quantification of a pair of diastereoisomenc alkaloids（ephedrine and pseudoephedrine）.The limits of detection（S/N = 3） were 4.5×10^-8 mol/L for ephedrine and 5.2×10^-8 mol/L for pseudoephedrine,respectively.The RSDs of migration time and peak area were less than 1.3 and 2.5%（n = 5）,respectively.The applicability of the propose method was illustrated in the determination of ephedrine and pseudoephedrine in human urine,ephedrine in nasal drops,and the monitoring of pharmacokinetics for pseudoephedrine.     

化学计量学-动力学分光光度法同时测定两种糖皮质类激素

在碱性介质中,高锰酸钾能将糖皮质类激素(醋酸泼尼松和地塞米松)氧化,而本身被还原成绿色的锰酸钾,基于这一反应,本文提出了同时测定醋酸泼尼松和地塞米松的化学计量学-动力学分光光度法.研究发现反应体系在610 nm处有一个吸收峰,实验以该波长为检测波长,优化实验条件.在该条件下,检测醋酸泼尼松和地塞米松的线性范围分别为0....     

A fast, comprehensive screening method for doping agents in urine by gas chromatography-triple quadrupole mass spectrometry

The use of performance enhancing drugs in sports is prohibited. For the detection of misuse of such substances gas chromatography or liquid chromatography coupled to mass spectrometry are the most frequently used detection techniques. In this work the development and validation of a fast gas chromatography tandem mass spectrometric method for the detection of a wide range of doping agents is described. The method can determine 13 endogenous steroids (the steroid profile), 19-norandrosterone, salbutamol and 11-nor-Δ9-tetrahydrocannabinol.9carboxylic acid in the applicable ranges and to detect qualitatively over 140 substances in accordance with the minimum required performance levels of the World Anti-Doping Agency in 1ml of urine. The classes of substances included in the method are anabolic steroids, β2-agonists, stimulants, narcotics, hormone antagonists and modulators and beta-blockers. Moreover, using a short capillary column and hydrogen as a carrier gas the run time of the method is less than 8min.