Trace element profiles in the hair of Nasopharyngeal carcinoma (NPC) patients

The trace element profiles of the scalp hair of NPC patients, aged between 30 and 69, were measured using neutron activation analysis and compared with those of normal healthy people within the same age bracket. The washing method of using detergent and washing powder was found to be comparable to that of using ether. Difference in the mean concentration of each element in the two groups was tested by Student's t-test. A significantly lower value of strontium (Sr) and significantly higher values of arsenic (As), iron (Fe) and vanadium (V) were found in the hair of NPC patients. The relative values of As and Fe found were consistent with the results of other findings on NPC patients, using different measuring methods. The V content in the hair of NPC patients was three times that of healthy people.     

Synthesis of novel apio carbocyclic nucleoside analogues as selective a(3) adenosine receptor agonists

On the basis of the biological activity of neplanocin A and apio-dideoxyadenosine (apio-ddA), novel apio-neplanocin A analogues 5a-d, combining the properties of two nucleosides, were stereoselectively synthesized. The apio moiety of the target nucleosides 5a-d was stereoselectively introduced by treating lactol 10 with 37% formaldehyde in the presence of potassium carbonate. The carbasugar moiety of neplanocin A was successively built by exposing diene 12 on a Grubbs catalyst in methylene chloride. The final nucleosides 5a-d were synthesized from the condensation of the glycosyl donor 14 with nucleic bases under the standard Mitsunobu conditions. Similarly, apio-aristeromycin 6 and (N)-apio-methanocarbaadenosine 7 were derived from the common intermediate 13 using catalytic hydrogenation and Simmons-Smith cyclopropanation as key steps. All of the final nucleosides 5a-d, 6, and 7 did not show significant inhibitory activity against S-adenosylhomocysteine hydrolase (SAH) up to 100 muM, maybe due to the absence of the secondary hydroxyl group at the C3'-position, which should be oxidized by cofactor-bound NAD(+). However, apio-neplanocin A (5a) showed potent and highly selective binding affinity (K(i) = 628 +/- 69 nM) at the A(3) adenosine receptor without any binding affinity at the A(1) and A(2A) adenosine receptors. In conclusion, we have first developed novel carbocyclic nucleosides with unnatural apio-carbasugars using stereoselective hydroxymethylation and RCM reaction and also discovered a new template of human A(3) adenosine receptor agonist, which play a great role in developing new A(3) adenosine receptor agonist as well as in identifying the binding site of the receptor.     

Engineering Pt in ceria for a maximum metal-support interaction in catalysis

Conventional supported metal catalysts are metal nanoparticles deposited on high surface area oxide supports with a poorly defined metal-support interface. Typically, the traditionally prepared Pt/ceria catalyzes both methanation (H2/CO to CH4) and water-gas shift (CO/H2O to CO2/H2) reactions. By using simple nanochemistry techniques, we show for the first time that Pt or PtAu metal can be created inside each CeO2 particle with tailored dimensions. The encapsulated metal is shown to interact with the thin CeO2 overlayer in each single particle in an optimum geometry to create a unique interface, giving high activity and excellent selectivity for the water-gas shift reaction, but is totally inert for methanation. Thus, this work clearly demonstrates the significance of nanoengineering of a single catalyst particle by a bottom-up construction approach in modern catalyst design which could enable exploitation of catalyst site differentiation, leading to new catalytic properties.     

Deposition of Titania Nanoparticles on Spherical Silica

Titania coated silica nanoparticles were prepared through a sol-gel process using peptized TiO₂ nano-sols. The TiO₂ sols were obtained by peptization, the process of redispersing a coagulated colloid, and were coated on SiO₂ particles by the control of the weight ratio of TiO₂/SiO₂ and the pH of the mixture in aqueous solution. At pH 4.5 the difference of zeta-potential between SiO₂ and TiO₂ maximized and then the TiO₂-coated SiO₂ particles with highest TiO₂ contents (20%) were obtained without the self-aggregation of TiO₂ sols. The morphologies of particles were characterized with field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) and the isoelectric points (IEP) of particles were measured by zeta potential. The nature of exposed titanium ions on the surface of titania-coated silica nanoparticles was elucidated by X-ray photoelectron spectroscopy (XPS).     

Determination of non-steroidal estrogens in breast milk,plasma, urine and hair by gas chromatography/mass spectrometry

It is suspected that all the natural estrogens occurring in the human body, as well as dietary and synthetic estrogens, diversely affect the endocrine system depending on their exposure patterns. More rapid, reliable and accurate measurements of these compounds in various biological matrices are thus becoming an important task. After solid-phase extraction using an Oasis HLB extraction cartridge, the estrogen concentrates were derivatized with a mixture of N-methyl-N-trifluorotrimethylsilylacetamide/ammonium iodide/dithioerythritol (1000:4:5, v/w/w) for analysis by gas chromatography/mass spectrometry in the selected ion-monitoring (SIM) mode. The qualitative identification of estrogens detected in SIM mode was further confirmed by tandem mass spectrometry using low-energy collision-induced dissociation (CID) mode. The method for the assay of the 20 estrogens was linear over the ranges of 1-1000 micro g/L for biological fluids and 1-200 micro g/kg for hair with high correlation coefficient (>0.99). The limits of quantitation (LOQ) ranged from 1.0-10 micro g/L (or micro g/kg) and the limit of detection ranged from 0.2-3 micro g/L (or micro g/kg). The average precision (% CV) and accuracy (% bias) of the method determined at the LOQ, low, and medium concentrations were in the ranges 2.6-9.2 and -4.1-7.7, respectively. The average extraction recovery of the estrogens from plasma and hair at the three concentration levels varied in the ranges 77-103% (1.9-14.3% CV) and 73-104% (3.1-14%), respectively. The distribution patterns of the estrogens were characteristic of each biosample. Five estrogens in the range 1.5-44.9 micro g/L were measured in breast milk, 8 estrogens in the range 3.5-322 micro g/L in plasma, 12 estrogens at 1.2-442 micro g/L in urine, and biochanin-A at 13.2-39.1 micro g/kg in hair. Because of its high sensitivity, good precision and specificity, the present method was found suitable for the trace analysis of dietary and synthetic estrogens in complex biosamples such as breast milk, plasma, urine and hair.     

A symmetric derivative of the trimetallic nitride endohedral metallofullerene, Sc3N@C80.

The reaction of Sc3N@C80 with 6,7-dimethoxyisochroman-3-one (13C labeled) provides the first functionalized derivative of the trimetallic nitride template (TNT) endohedral metallofullerene family. The reaction mixture is dominated by a single 13C labeled monoadduct product that was purified by HPLC. The 13C labeled monoadduct was characterized by 1H NMR, 13C NMR, and MALDI-TOF mass spectrometry. The proposed structure for this novel symmetric monoadduct is consistent with derivatization at the [5,6] ring juncture on the Sc3N@C80 cage.     

Radical Copolymerization of Fluoroalkyl Methacrylates with Methyl Methacrylate

Lauryl peroxide initiated radical copolymerization of 1,1,3-trihydroperfluoropropyl methacrylate and 1,1,5-trihydroperfluoroamyl methacrylate with methyl methacrylate was studied. The kinetic parameters of copolymerization for these systems were determined at low degrees of conversion. Optically transparent copolymers with glass transition points within 50–80°C were synthesized.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 818–821.Original Russian Text Copyright © 2005 by Man’ko, Mel’nichenko, Bovkunenko, Shendrik, Fedoseeva, Goncharov.     

分形表面粗糙度与光散射关系的研究

用Weielstxass－Mandelbrot函数产生了一维的分形表面，在几何光学适用的范围内研究了这些表面的光散射特性．发现分形线数D越大，通常被认为越粗糙的表面，其光散射的角分布反而比D小的表面更集中．文章最后解释了这种现象的成因．     

基于多层电介质光栅光谱合成的光束质量

基于电介质光栅的光谱合成是实现高功率高光束质量激光的重要途径. 在电介质光栅的光谱合成系统中, 光栅色散效应是影响合成激光光束质量的重要因素. 本文推导了单光栅和双光栅光谱合成系统中由于光栅色散引起M²因子的变化公式; 详细讨论了这两种合成系统中单路激光线宽、单路激光光斑半径、相邻两路激光波长差、相邻两路激光间距以及光栅周期对光束质量的影响. 研究表明对于单光栅合成系统, 在合成过程中若保持光束质量M²因子的大小不变, 则单路激光带宽随光斑半径的增加而减小; 在双光栅光谱合成系统中, 在保持光束质量的前提下, 单路激光带宽可随光斑半径的增大而相应增加. 数值计算表明, 若要满足合成光束的光束质量M² ≤1.2的要求, 在单光栅系统中激光线宽需窄于亚纳米量级, 在双光栅系统中激光带宽可为亚纳米. 本文为高功率、高光束质量的光纤激光光谱合成系统的搭建提供了理论指导.     

铁和镧共掺杂纳米二氧化钛光催化剂的制备、表征及其光催化活性

以葡聚糖为模板,钛酸四正丁酯、硝酸铁和硝酸镧为前驱体采用模板法制备了一系列铁、镧单掺杂及共掺杂纳米TiO₂光催化剂. 利用SEM、XRD、BET比表面积测定和UV-Vis等技术对其形貌、晶体结构及表面结构、光吸收特性等进行了表征. 以甲基橙溶液的光催化降解为模型反应,考察了不同掺杂的样品在紫外和可见光下的光催化性能. TiO₂材料具有较大的比表面积(约150 m²/g),铁和镧共掺杂纳米TiO₂在可见光区域有较强的吸收,在紫外和可见光条件下较纯TiO₂和单掺杂TiO₂对甲基橙溶液具有更好的光催化降解效果,且铁和镧的掺杂量显著影响该材料的催化性能. 当铁掺杂量为0.5mol%、镧掺杂量为0.3mol%,在500 ℃焙烧2 h所得光催化材料的催化性能最佳,焙烧4 h即可使甲基橙的降解率达98.8%,且该复合材料有较高的循环回收利用率,重复使用4次仍可使甲基橙的降解率保持在88%以上.