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1.
Alexandre Stojanovic 《Mathematical Physics, Analysis and Geometry》2004,7(4):347-349
The errata concern mainly the last computations for the universality of the local statistics of eigenvalues at the edge of the spectrum in parts (iii) of Theorems 2.3 and 2.4. 相似文献
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Lanthanum doped bismuth titanate thin films (Bi3.25La0.75Ti3O12 - BLT) were produced by the polymeric precursor method and crystallized in a domestic microwave oven and in conventional furnace. Using platinum coated silicon substrates configuration, ferroelectric properties of the films were determined with remanent polarization Pr and a coercive field Ec of 3.9 μC/cm2 and 70 kV/cm for the film annealed in the microwave oven and 20 μC/cm2 and 52 kV/cm for the film annealed in conventional furnace, respectively. The films annealed in conventional furnace exhibited excellent retention-free characteristics at low infant periods indicating that BLT thin films can be a promise material for use in non-volatile memories. On the other hand, the pinning of domains wall causes a strong decay at low infant periods for the films annealed in the microwave furnace which makes undesireable the application for future FeRAMS memories. 相似文献
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Simultaneous determination of copper, zinc, cadmium and mercury with high sensitivity is possible by neutron activation analysis. After irradiation, the samples are digested and an initial separation of the four elements made by means of an ion-exchange resin. The elements in the separated fractions are then treated to give radio-chemical purity, precipitated, and their activities measured. A purely instrumental technique for the analysis of zinc in samples of biological material is also described. The samples are irradiated for a week and after the activity has decayed for about three months it is measured on a gamma-spectrometer. 相似文献
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Milica Lukic Ivana Pantelic Rolf Daniels Christel Müller-Goymann Miroslav Savic Snezana Savic 《Journal of Thermal Analysis and Calorimetry》2013,111(3):2045-2057
Mesomorphic behavior of the novel long-chain alkyl polyglucoside emulsifier comprising arachidyl alcohol (C20), behenyl alcohol (C22), and arachidyl glucoside was investigated in order to determine the prevalent stabilization mechanism and moisturizing capacity of emulsion systems based on it. For this to be accomplished thermoanalytical methods (differential scanning calorimetry and thermogravimetric analysis) coupled with microscopy, rheological, X-ray diffraction methods and a short-term in vivo study of skin hydration level were performed. Obtained results have proved that C20/C22 alkyl polyglucoside mixed emulsifier is able to provide the synergism between the two main types of lamellar phases, the liquid-crystalline (Lα), and the gel crystalline (Lβ) one, building the emulsion systems of different stability and performance. Formation of lamellar structures influenced for more than one half of water within the system to be entrapped. Conducted investigation of hydration potential in real-time conditions provided valuable information on the investigated emulsion vehicles’ moisturizing potential as well as their contribution to the skin barrier improvement. Therefore, it could be expected that emulsions based on this alkyl polyglucoside emulsifier could influence the delivery of active ingredients of both the lipophilic and hydrophilic type. The employment of thermoanalytical methods in our work suggests the possibility for thermal methods to be used more frequently in the characterization of both the novel raw materials and the belonging emulsion systems. 相似文献
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Fan X Medved M Karczmar GS Yang C Foxley S Arkani S Recant W Zamora MA Abe H Newstead GM 《Magnetic resonance imaging》2007,25(5):593-603
The purpose of this study was to test whether an empirical mathematical model (EMM) of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can distinguish between benign and malignant breast lesions. A modified clinical protocol was used to improve the sampling of contrast medium uptake and washout. T(1)-weighted DCE magnetic resonance images were acquired at 1.5 T for 22 patients before and after injection of Gd-DTPA. Contrast medium concentration as a function of time was calculated over a small region of interest containing the most rapidly enhancing pixels. Then the curves were fitted with the EMM, which accurately described contrast agent uptake and washout. Results demonstrate that benign lesions had uptake (P<2.0 x 10(-5)) and washout (P<.01) rates of contrast agent significantly slower than those of malignant lesions. In addition, secondary diagnostic parameters, such as time to peak of enhancement, enhancement slope at the peak and curvature at the peak of enhancement, were derived mathematically from the EMM and expressed in terms of primary parameters. These diagnostic parameters also effectively differentiated benign from malignant lesions (P<.03). Conventional analysis of contrast medium dynamics, using a subjective classification of contrast medium kinetics in lesions as "washout," "plateau" or "persistent" (sensitivity=83%, specificity=50% and diagnostic accuracy=72%), was less effective than the EMM (sensitivity=100%, specificity=83% and diagnostic accuracy=94%) for the separation of benign and malignant lesions. In summary, the present research suggests that the EMM is a promising alternative method for evaluating DCE-MRI data with improved diagnostic accuracy. 相似文献
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Božidar Čobeljić Andrej Pevec Stepan Stepanović Milica R. Milenković Iztok Turel Maja Gruden Dušanka Radanović Katarina Anđelković 《Structural chemistry》2018,29(6):1797-1806
The isothiocyanato Zn(II) complex (1) and mixed isothiocyanato/thiocyanato Cd(II) complex (2) with the condensation product of 2-acetylpyridine and trimethylammoniumacetohydrazide chloride (Girard’s T reagent) (HLCl) were investigated both experimentally and theoretically. The crystal structures of both complexes showed tridentate N2O coordination of hydrazine ligand. In complex 1 square-pyramidal coordination surrounding of Zn(II) consists of deprotonated hydrazone ligand and two isothiocyanato ligands, while in octahedral Cd(II) complex ligand is coordinated without deprotonation as a positively charged species and coordination geometry is completed with two N-coordinated and one S-coordinated NCS? anions. NMR spectroscopy and molar conductivity results for Cd(II) and Zn(II) complexes indicated their instability in solution. DFT calculations were performed to explain coordination preference and stability of complexes 1 and 2 in solid state and in solution. The obtained Cd(II) complex is the first reported mononuclear pseudohalide/halide Cd(II) complex with quinoline-/pyridine-based hydrazone ligands possessing octahedral geometry in solid state. In this complex, H-bonding has significant impact on coordination number and supramolecular assembly in solid state. 相似文献
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We review several sufficient conditions for the positive definiteness of a tridiagonal matrix and propose a different approach
to the problem, recalling and comprising little-known results on chain sequences. 相似文献