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161.
The elements Mn and V were determined by INAA in about 5 mg and 100 mg aliquots of NIST SRM 1648 to elucidate discrepancies between our previous results for the 0.5 mg to 15 mg aliquots and the NIST certified and/or information values. Simultaneously, other NIST SRMs 1633a, 2704, and BCR CRMs 038, 101 and 143 were also analyzed. Special attention was given to evaluating and minimizing uncertainties of all steps of analysis. Our results compared very well with the respective certified and/or information values (if available) of all SRMs and CRMs studied, except for NIST SRM 1648. For this SRM we have found significantly lower results than the NIST values which suggests that the NIST values are positively biased by about 10%. A new value for V in BCR CRM 143 was also obtained. 相似文献
162.
Doz. Dr. Miroslav Ebert Ladislav Kavan 《Monatshefte für Chemie / Chemical Monthly》1975,106(6):1499-1512
Iron(III) phosphites, vic. Fe2(HPO3)3·9 H2O, FeH3P2O6·3 H2O, FeH6P3O9·H2O and Fe4H33P15O45·6 H2O were studied by means of powder X-ray, thermographic, IR and UV spectroscopy methods and by measurement of magnetic susceptibility. From the results obtained, and from analogy with phosphites studied earlier, the following structural model can be proposed: in the compounds studied, every iron atom is surrounded by six oxygen atoms of the water molecules and phosphite or, polyorthophosphite anions which form a weak ligand field of approximately octahedral symmetry. In Fe2(HPO3)3·9 H2O, symmetry of the anion is decreased from the point group C3v to the Cs group. This anion is characterised by two bonding distances between phosphorus and oxygen atoms,r PO=1,46 Å andr PO 2=1,50 Å, the respective force constants beingK PO=8.7 mdyn/Å andK PO2=7.1 mdyn/Å. Three types of hydrogen bonds occur in the crystal lattices of the compounds studied. The weakest bond (bond lengthr=2.86–2.88 Å, bond energyE=4.6–5.0 kcal/bond) is formed between molecules of hydrate water, its energy approaching that of the hydrogen bond in liquid water. The stronger hydrogen bond (r=2.67–2.70 Å,E=5.7 to 8.0 kcal/bond) is found between water molecules and phosphite or polyorthophosphite anions. The strongest hydrogen bond (r=2.55–2.64 Å) is formed by polyorthophosphite anions, linking hydroxyl groups to oxygen atoms bound to different phosphorus atoms. 相似文献
163.
Jana Bludská Ivo Jakubec Dušan Nohavica Ladislav Pekárek 《Czechoslovak Journal of Physics》1999,49(5):775-781
We report on preparation of p-In1−x
Ga
x
P polycrystalline, p-In0.5 Ga0.5P/p-GaAs, and p-In0.5 Ga0.5P/n-GaAs/n-InP tandem-type cathodes. The photovoltaic efficiency of InGaP tandem type epitaxial electrodes is two times higher
than that of polycrystalline photocathodes. The most significant advantage of epitaxial electrodes is in their markedly better
corrosion resistance in comparison with polycrystalline photocatodes.
Presented at the 1st Czech-Chinese Workshop “Advanced Materials for Optoelectronics”, Prague, Czech Republic, June 13–17,
1998. 相似文献
164.
Simon Cousy Nataliia Gorodylova Ladislav Svoboda Jiri Zelenka 《Chemical Papers》2017,71(12):2325-2334
Simonkolleite is a zinc-layered hydroxide salt with the formula Zn5(OH)8Cl2·H2O. It has a platelet morphology and can be used for many applications, owing to both its layered structure and its nature as a hydroxide salt. It can be prepared via a simple precipitation from ZnCl2 and NaOH in water thermostated at 50 °C. Depending on the synthesis conditions, we could obtain different sizes and a hybrid containing parts of ZnO. We studied the influence of the OH:Zn molar ratio, the addition order, and the maturation time after the reaction was completed. With the support of pH profiles, kinetic studies, and thermodynamic equilibrium data, we were able to propose a global synthesis mechanism explaining the influence of those three parameters and identify the range of conditions in which simonkolleite can be formed. Depending on the desired application, we were able to synthesize bigger or smaller layered crystals of simonkolleite, in the presence of absence of ZnO. 相似文献
165.
L. Bohat P. Becker H. Rhee O. Lux H.J. Eichler H. Yoneda A.A. Kaminskii 《Laser \u0026amp; Photonics Reviews》2012,6(5):690-701
For calcite (CaCO3), one of the pioneer crystals in nonlinear optics, new results of stimulated Raman scattering (SRS) spectroscopy are presented. Among them are the discovery of a new SRS‐promoting vibration mode with ωSRS2 ≈︁ 282 cm‐1 and its participation, together with the main SRS mode ωSRS1 ≈︁ 1086.5 cm‐1, in cross‐cascaded (χ(3) ↔ χ(3)) nonlinear‐lasing generation, as well as the observation of efficient self‐upconversion via cascaded parametric four‐wave processes of one‐micron Stokes and anti‐Stokes χ(3)‐lasing into the UV‐region of third harmonic generation. The investigations show that calcite is able to generate a χ(3)‐lasing comb of more than two octaves bandwidth. The article also gives a brief review on the discovery and study of the SRS‐effect in natural crystals (minerals), which have expanded our ability to study the photon‐phonon nonlinear‐laser interactions in crystalline materials. A short summary of information about χ(3)‐lasing properties of the triangular planar structure units in SRS‐active crystals is included. 相似文献
166.
Kalenda Petr Koudelka Ladislav Mošner Petr Beneš Ludvík Černošek Zdeněk 《Journal of Thermal Analysis and Calorimetry》2018,131(3):2303-2310
Journal of Thermal Analysis and Calorimetry - The thermal behavior and crystallization of barium molybdate-phosphate glasses were studied in two compositional series, namely A:... 相似文献
167.
Jaroslav Blaško Róbert Kubinec Ivan Ostrovský Eva Pavlíková Ján Krupčík Ladislav Soják 《Journal of chromatography. A》2009,1216(14):2757-2761
A generally known problem of GC separation of trans-7;cis-9; cis-9,trans-11; and trans-8,cis-10 CLA (conjugated linoleic acid) isomers was studied by GC–MS on 100 m capillary column coated with cyanopropyl silicone phase at isothermal column temperatures in a range of 140–170 °C. The resolution of these CLA isomers obtained at given conditions was not high enough for direct quantitative analysis, but it was, however, sufficient for the determination of their peak areas by commercial deconvolution software. Resolution factors of overlapped CLA isomers determined by the separation of a model CLA mixture prepared by mixing of a commercial CLA mixture and CLA isomer fraction obtained by the HPLC semi-preparative separation of milk fatty acids methyl esters were used to validate the deconvolution procedure. Developed deconvolution procedure allowed the determination of the content of studied CLA isomers in ewes’ and cows’ milk samples, where dominant isomer cis-9,trans-11 is eluted between two small isomers trans-7,cis-9 and trans-8,cis-10 (in the ratio up to 1:100). 相似文献
168.
169.
Ladislav Ceniga 《Meccanica》2015,50(9):2421-2430
170.
Ladislav Ceniga 《Acta Mechanica Sinica》2010,26(5):695-709
This paper deals with an analytical model of thermal stresses which originate during a cooling process of an anisotropic solid continuum with uniaxial or triaxial anisotropy. The anisotropic solid continuum consists of anisotropic spherical particles periodically distributed in an anisotropic infinite matrix. The particles are or are not embedded in an anisotropic spherical envelope, and the infinite matrix is imaginarily divided into identical cubic cells with central particles. The thermal stresses are thus investigated within the cubic cell. This mulfi-particle-(envelope)-matrix system based on the cell model is applicable to two- and three-component materials of precipitate-matrix and precipitate-envelope-matrix types, respectively. Finally, an analysis of the determination of the thermal stresses in the multi-par- ticle-(envelope)-matrix system which consists of isotropic as well as uniaxial- and/or triaxial-anisotropic components is presented. Additionally, the thermal-stress induced elastic energy density for the anisotropic components is also derived. These analytical models which are valid for isotropic, anisotropic and isotropic-anisotropic multi-particle- (envelope)-matrix systems represent the determination of important material characteristics. This analytical determination includes: (1) the determination of a critical particle radius which defines a limit state regarding the crack initiation in an elastic, elastic-plastic and plastic components; (2) the determination of dimensions and a shape of a crack propagated in a ceramic components; (3) the determination of an energy barrier and micro-/macro-strengthening in a component; and (4) analytical-(experimental)-computational methods of the lifetime prediction. The determination of the thermal stresses in the anisotropic components presented in this paper can be used to determine these material characteristics of real two- and three-component materials with anisotropic components or with anisotropic and isotropic components. 相似文献