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61.
D.L. Wainstein A.I. Kovalev Cs. Ducso T. Jaszi P. Basa Zs.J. Horvath T. Lohner P. Petrik 《Physica E: Low-dimensional Systems and Nanostructures》2007,38(1-2):156
Si nanocrystals were formed in the non-stoichiometric Si-enriched SiNx low-pressure chemical vapor deposited (LPCVD) coatings on Si wafers treated by various modes. The coating structure as a function of technological conditions was investigated by ellipsometry and X-ray photoelectron spectroscopy (XPS) depth profiling. It was found that nanocomposites on base of SiNx films enriched by Si have a complex multilayered structure varying in dependence of deposition and annealing parameters. Analysis of the XPS spectra and Si 2s peaks shows the existence and quantity of four chemical structures corresponding to the Si–O, Si–N states, nanocrystalline and amorphous Si. The XPS results show evolution of the chemical structure of silicon nitride and formation of Si nanocrystals. It was found:
- • The LPCVD technology of nanocrystals formation allows to get enough high concentration of Si nanocrystals on different depths from the sample surface.
- • The volume fraction of nanocrystalline and amorphous Si is changed with depth; this relation depends from SiNx composition and annealing parameters.
- • XPS detects these two phase compositions of Si nanoparticles in SiNx and SiO2 layers. The ellipsometry, HR-TEM, and XPS results are in good agreement.
Keywords: Nano crystals; Si 相似文献
62.
Zsolt Zsótér Tibor Tímár Krisztina Kónya Tamás Patonay József Jekő 《Journal of heterocyclic chemistry》2015,52(6):1677-1683
4,4‐Dimethylchromeno[4,3‐d]selenadiazoles 8 with insecticide activities have been synthesized via oxidative ring closure of the corresponding semicarbazone derivatives 7 by treatment with selenium dioxide. Reaction of various alkoxy‐2,2‐dimethyl‐2H‐benzopyrans with phenylselenyl chloride was utilized to prepare different phenylselenyl‐ and 3‐chloro precocene analogs. 相似文献
63.
P. K��d��r K. Varga B. Baja Z. N��meth N. Vajda Zs. Stef��nka L. K?v��r I. Cserny J. T��th T. Pint��r J. Schunk 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):943-954
Within the frame of a joint project, the accumulation of the uranium and transuranium (TRU) species on some structural materials used at Soviet made VVER-type pressurized water reactors (such as heat exchanger tube of steam generators and stainless steel canister material) has been studied. The experiments were carried out in a laboratory model system. During the sorption studies, boric acid coolants provided by the Paks Nuclear Power Plant (Paks NPP) were circulated for a period of 30 h. Solution and tube samples obtained in the course of above experiments were analyzed by independent methods (??- and ??-spectrometry, ICP-MS, SEM-EDX, voltammetry and XPS). The experimental results reveal that: (i) the surface excess of the TRU nuclides studied is extremely low (less than 1% of a monolayer coverage); (ii) the surface excess of uranium species measured on the SG tube surfaces is significantly higher, after 30 h sorption period (??sample = 1.0 ??g cm?2 U ? 3.7 × 10?9 mol cm?2 UO2) exceeds a monolayer coverage; (iii) the mechanistic features of the contamination processes (specific or non-specific adsorption, deposition of colloidal and/or disperse particles) depend decisively upon the nature of the studied radionuclides and the chemical structure and composition of the oxide layer formed on stainless steel surfaces. 相似文献
64.
During the past few years, general-purpose graphics processing units (GPGPUs) have become rather popular in the high performance computing community. In this study, we present an implementation of the simulation of dynamic nuclear magnetic resonance (DNMR) spectra. The algorithm is based on the kinetic Monte Carlo method and therefore can benefit from the multithreaded architecture of the GPGPU. By careful optimization of the algorithm a 30-100-fold speed increase could be achieved. 相似文献
65.
Sz. Osváth N. Vajda Zs. Stefánka É. Széles Zs. Molnár 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):459-463
A combined radioanalytical method for determination of 93Zr and 237Np (as well as other actinoids) in radioactive wastes has been developed. Analytes were co-precipitated on iron(II)-hydroxide,
separated and purified on UTEVA columns, and detected by inductively coupled plasma mass spectrometry. According to Zr and
Np, 65 and 75% yields were achieved, respectively. 相似文献
66.
Polgári Z Ajtony Z Kregsamer P Streli C Mihucz VG Réti A Budai B Kralovánszky J Szoboszlai N Záray G 《Talanta》2011,85(4):1959-1965
Microanalytical methods suitable for the determination of Fe, Cu in HT-29 (human colon adenocarcinoma) cells treated with different iron compounds (Fe(II) sulfate, Fe(III) chloride, Fe(III) citrate and Fe(III) transferrin) and cultured in medium supplemented or not with 10% (v/v) fetal calf serum (FCS) by total reflection X-ray fluorescence spectrometry (TXRF) and simultaneous graphite furnace atomic absorption spectrometry (GF-AAS) were developed. The developed TXRF method was also suitable for Zn determination in the samples. The main advantage of the proposed methods is the execution of all sample preparation steps following incubation and prior to the elemental analysis in the same Eppendorf tubes. Sample preparation was performed at microscale (115 μL sample volume) with 65% nitric acid and 30% hydrogen peroxide. According to scanning electron microscopic measurements, the organic matrix of the cell samples could be eliminated to the extent that accurate results were obtained for Cu and Fe by analyzing the same samples by TXRF and GF-AAS. Concerning the iron uptake, HT-29 cells incubated in FCS-free medium contained Fe in cca. 5-50 times higher amounts compared to cells cultured in FCS supplemented medium. Pronounced differences in the iron uptake compared to the iron supply (inorganic vs. organic chelated as well as iron(II) vs. iron(III)) were observed in the case of cell lines incubated in FCS-free medium. 相似文献
67.
Summary Steroid metabolites have been measured by capillary gas chromatography in the urine of 38 children aged 3–6 years. The children
comprised three groups: those with asthma being treated with Terbutaline (13), children with asthma but not undergoing treatment
(17), and control children in hospital but free from endocrine diseases (8). There were significant (P<0.05) differences between the amounts of steroids excreted by the different groups of children. Terbutaline therapy led to
elevated levels of tetrahydrocortisone, androstenediol, 11-ketopregnanetriol and a reduced ratio of androgen to cortisol metabolites
compared with those for untreated asthmatic children. We assume that Terbutaline does not have a steroid-like mechanism of
action but acts by modification of the activity of several adrenocortical enzymes. We suggest a hypothesis whereby the antiasthmatic
effect of Terbutaline could not only be a connected with its well-known mechanism of action, but it might be explained as
a result of the modification of the production of certain glucocorticoids and androgen hormones.
Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997. 相似文献
68.
Zs. Révay T. Belgya G. L. Molnár 《Journal of Radioanalytical and Nuclear Chemistry》2005,265(2):261-265
Summary Hypermet-PC has been developed in the mid-nineties at the Institute of Isotopes and Surface Chemistry based on a successful FORTRAN code from the seventies. With additional calibration routines and other helping features it has proved to be a very useful tool in quantitative analysis performed either with NAA or with PGAA. The sophisticated built-in peak-shape function allows the fitting of asymmetric peaks from large-volume germanium detectors over a very wide energy range needed for PGAA. The experience collected when evaluating several thousands gamma-spectra acquired for routine analysis and spectroscopic research, is summarized in the paper. 相似文献
69.
F. Raiola B. Burchard Zs. Fülöp Gy. Gyürky S. Zeng J. Cruz A. Di Leva B. Limata M. Fonseca H. Luis M. Aliotta H. W. Becker C. Broggini A. D'Onofrio L. Gialanella G. Imbriani A. P. Jesus M. Junker J. P. Ribeiro V. Roca C. Rolfs M. Romano E. Somorjai F. Strieder F. Terrasi 《The European Physical Journal A - Hadrons and Nuclei》2006,27(1):79-82
70.
G. Petõ G. Molnár L. Dózsa Z.E. Horváth Zs.J. Horváth E. Zsoldos C.A. Dimitriadis L. Papadimitriou 《Applied Physics A: Materials Science & Processing》2005,81(5):975-980
Epitaxial and polycrystalline orthorhombic GdSi2 films were grown on Si(100) substrates by solid phase reaction between Si and Gd films at different thicknesses of the Gd film . The most important property of these GdSi2/Si interfaces was defect formation. This was investigated by studying the properties of the Schottky barriers by means of current voltage and capacitance–voltage characteristics, deep level transient spectroscopy by double crystal X-ray diffractometry, and transmission electron microscopy. Epitaxial growth of the silicide layer ensured a relatively low interface defect density (about 1010 cm-2), while the non-epitaxial growth induced defects of a much higher density (about 1012 cm-2). The defects generated during the silicide formation are located within a depth of about 10 nm from the GdSi2/Si interface. PACS 68.55.-a; 73.40.-c; 81.15-zThis revised version was published in March 2005. References 10-17 were added in the online version (pdf file). 相似文献