Influence of the Native Oxide Layer on the Silicon Surface During Initial Stages of Nitridation

 Thin SiO₂ layers were produced by thermal oxidation of Si wafer material. To study the effect of nitridation on the oxide layers, the specimens were nitrided in a furnace at high temperature. Non-destructive ion beam analysis was performed to determine changes in the elemental concentrations and depth profiles of the major components. In particular, N and O concentrations were measured using the non-resonant nuclear reactions ¹⁴N(d, α)¹²C and ¹⁶O(d, p)¹⁷O, respectively. To obtain depth profiles of the as-prepared and nitrided specimens, the samples were measured with RBS and heavy ion elastic recoil detection analysis. The ion beam analyses revealed an increase in thickness of the SiO₂ layers with temperature. The specimens nitrided at 1200 °C were almost free of N. Surface topology investigations with scanning electron microscopy revealed concentric annular artificial patterns at the surfaces. In the centre of the pattern, only silicon was measured. Additionally, a band consisting of Si, O, and N surrounding the pattern was discovered. The findings are in agreement with specimens prepared at higher temperatures. Received June 19, 2000. Revision December 9, 2000.     

An efficient Fe(III)-catalyzed 1,6-conjugate addition of para-quinone methides with fluorinated silyl enol ethers toward β,β-diaryl α-fluorinated ketones

Reported here is a highly efficient 1,6-conjugate addition of fluorinated silyl enol ethers to para-quinone methides, allowing facile access to a range of β,β-diaryl α-fluorinated ketones with good to high yields. Fe(OTf)₃ was identified as the optimal catalyst, with the loading of 3?mol%. Notably, this represent the first 1,6-conjugate addition with fluorinated silyl enol ethers. The synthetic potential of the resulting adducts is also demonstrated.     

Application of pathways activity profiling to urine metabolomics for screening Qi‐tonifying biomarkers and metabolic pathways of honey‐processed Astragalus

Honey‐processed Astragalus, a widely used Qi‐tonifying and immunomodulating herb in traditional Chinese medicine, has strengthened the tonic effects and achieved fewer side effects compared with astragali radix in clinical application. Here, we focus on Qi‐tonifying biomarkers and pathways of honey‐processed Astragalus using urine metabolomics that provide the basis for building the linkage between metabolites in rat urine and its symptoms. The spleen Qi deficiency model group, normal group, astragali radix group, and honey‐processed Astragalus group were implemented to evaluate Qi‐tonifying effects. Twelve potential biomarkers were screened by multivariate statistical analysis by using ultra high performance liquid chromatography with quadrupole time‐of‐flight mass spectrometry. Furthermore, pathways activity profiling showed unique pathways that are primarily involved in tryptophan metabolism, tricarboxylic acids cycle, and methionine metabolism. The results demonstrated that metabolomics coupled with pathway activity profiling were promising tools. It might serve as a novel methodological clue to systematically dissect the underlying Qi‐tonifying mechanism of honey‐processed Astragalus.     

电感耦合等离子体发射光谱法(ICP-AES)测定高铼酸钾中的19种杂质元素

建立了一种用稀盐酸溶解样品,标准工作溶液中匹配钾,ICP-AES测定高铼酸钾中19种杂质元素的方法。在选定的仪器工作条件下,样品加标回收率(%)分别为：钠94.4～101、钙98.8～102、铝98.1～102、镁95.8～99.1、钴98.4～101、钼97.3～103、钛97.6～102、钒96.6～106、锆96.2～97.7、铬97.8～101、铜98.1～108、铁92.9～104、锰95.5～98.4、镍93.6～101、钯93.3～101、铅96.5～103、锌95.2～103、铂95.9～99.9、铑94.5～96.3;方法精密度RSD%(n=7)分别为：钠2.0～5.5、镁1.1～3.5、铝0.9～2.5、钙1.5～7.3、钴1.1～3.1、钼0.9～4.5、钛1.0～2.8、钒1.6～4.0、锆1.4～3.6、铬0.77～4.6、铜0.74～1.8、铁1.3～3.8、锰1.1～2.0、镍0.99～5.0、钯1.1～2.4、铅1.3～9.1、锌0.80～6.7、铂1.2～10、铑0.78～8.6。方法简便、快速、准确, 满足生产分析要求。     

氧化镥中杂质对铈掺杂硅酸镥多晶粉体光谱性质影响

氧化镥中杂质元素对其分离制备工艺、生产成本及镥基硅酸盐闪烁晶体的性能有很大影响,但杂质元素对晶体的性质影响研究较为有限,有待进一步完善。 本文采用高温固相法制备了Lu₂O₃分离过程中关键杂质元素Yb³⁺和Ca²⁺共掺杂Lu₂SiO₅∶Ce多晶粉体,研究了Yb³⁺或Ca²⁺含量对多晶粉体光谱性质的影响,结果表明:Yb³⁺或Ca²⁺共掺并未改变发射光谱的形状和位置,随着杂质元素摩尔分数的增加,光谱强度和荧光寿命逐渐降低。     

Synthesis and characterizations of various polyvinyl pyrrolidon/hydroxyl ethyl methacrylate nanocomposite hydrogels as drug delivery systems

Using polymer hydrogels and nanocomposites hydrogels still promising materials for many applications. Polyvinyl pyrrolidone (PVP) has been used with various polymers synthetic and natural for different applications. In this study PVP and hydroxyl ethyl methacrylate (HEMA) copolymer hydrogels were prepared by the aid of gamma radiation and the PVP/HEMA nanocomposite hydrogels were obtained by in situ adsorption and reduction method of iron salts and silver nitrates (AgNO₃) to form PVP/HEMA-Fe₃O₄ and PVP/HEMA-Ag nanocomposites. The prepared hydrogels and the formed nanoparticles were studied by various techniques; FTIR, TEM, SEM and also the gel content and swelling behavior were evaluated. The prepared hydrogels and nanocomposites hydrogels were examined as drug delivery systems for Ciprofloxacin HCl as model drug. The PVP/HEMA-Fe₃O₄ nanocomposite gave the suitable load and release behavior towards Ciprofloxacin HCl.     

Synthesis and Characterization of Chitosan-Albumin Conjugates as pH-Sensitive Biodegradable Hydrogels

A new kind of biodegradable pH-sensitive drug delivery system was developed via chitosan-albumin conjugate hydrogel. Through changing the feeding modes of reactants, two types of hydrogels(comb-type and reticular-type) were synthesized by amidation reactions between 6-O-succinoylated N-phthaloyl chitosan and albumin. The structures and morphologies of the hydrogels were characterized by SEM. And their water swelling capacity, drug loading and releasing properties at different pH values were also investigate...     

低结晶度聚ε-己内酯电纺膜的制备及其药物控释行为

以芳氧基稀土三(2,6-二叔丁基-4-甲基苯氧基)镧(La(OAr)3)为催化剂,通过加入少量(8.5 mol%)碳酸2,2-二甲基三亚甲基酯(DTC)与ε-己内酯(CL)进行无规共聚合,成功制备了低结晶度的脂肪族内酯-碳酸酯无规共聚酯(PCD)材料,并用1H-NMR、SEC、DSC和WAXS证明了产物的结构和性能.以...     

The profiling and identification of chemical components,prototypes and metabolites of Run‐zao‐zhi‐yang capsule in rat plasma,urine and bile by an UPLC‐Q‐TOF/MSE‐based high‐throughput strategy

Run‐zao‐zhi‐yang (RZZY) capsule, a traditional Chinese medicine formula, is popularly used for the treatment of dermatitis and eczema. However, few studies have been carried out on RZZY and its metabolites. In this study, we developed a three‐step strategy to rapidly characterize the chemical constituents and metabolites of RZZY using ultra‐high‐performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry. A total of 41 chemical components were characterized from RZZY. Among these, there are 11 flavonoids, six alkaloids, six stilbene glycosides, five anthraquinones and 13 other compounds. In addition, 18 prototypes and 35 metabolites were detected in rat plasma, urine and bile. This study offers an applicable approach for high‐throughput profiling and identification of chemical components and metabolites derived from traditional Chinese medicine formula in vivo, and also provides essential data for exploring bioactive ingredients and action mechanisms of RZZY.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定锡精矿中8种杂质元素

应用电感耦合等离子体原子发射光谱(ICP-AES)法同时测定锡精矿中钙、镁、铜、铅、锌、砷、锑、铋8种杂质元素。对锡精矿样品的分解方法进行了合理选择,并对测定时的元素分析谱线、基体及各测定元素间干扰情况等进行了讨论。采用硝酸、盐酸、氢氟酸、高氯酸溶样,盐酸浸取。基体效应较小,各待测元素之间基本无干扰。测定结果与国家标准方法比对结果基本一致,相对标准偏差为1.3%~3.3%(n=11),方法加标回收率为96.0%~105%,能满足实际工作中准确、高效地分析锡精矿中杂质元素的需要。