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81.
The influence of the magnetic structures in thulium with the residual resistance ratio (RRR) of 140 on the electrical resistivity was determined from 4·2 K up to 70 K. The measurements indicated the Néel temperatureT
N = 57.5 K and the Curie temperature TC = 32 K. Furthermore, a new transition was found at TH = 49 K which did not appear in the neutron diffraction measurements.Dedicated to Dr. Svatopluk Krupika on the occasion of his 65th birthday.We would like to express our thanks to V. Sojeková and H. Bobulská for their assistance in the measurements. 相似文献
82.
A recently proposed simple qualitative theory of instability and reconstruction of surfaces of solids exhibiting a certain covalent component of bonding is applied to (2 x 1) Si (001) and (111) surfaces with a possible extension to analogous surfaces of germanium and GaAs (001)., Shockley surface states from the vicinity of the Fermi energy are supposed to play a crucial role in the electron-phonon coupling. For the Si (001) surface the interaction between bridge and dangling bonds causes the dimerization (primary effect) and the buckling distortions to couple. If the latter effect is pronounced, the asymmetric dimer might exist as a stable or metastable surface phase. For the Si (111) surface the Pandey -bonded chain model seems to be a natural candidate for reconstruction from the present simple point of view. 相似文献
83.
Methods of monitoring low plutonium concentration in the inner and outer atmosphere are analyzed and compared. It is shown that monitors based on the gross alpha counting of air filters are not sensitive enough to measure reliably plutonium activities below 1 MPC. A spectrometric discontinuously operating monitor using a gridded ionization chamber and a membrane filter having 70 cm2 active area is described. Plutonium activities of the order of 0.01 MPC /1 mBq.m–3/ can be measured by the spectrometer at 1 h sampling and 1 h counting time. 相似文献
84.
Š. Palágyi 《Journal of Radioanalytical and Nuclear Chemistry》1976,30(1):299-310
The separation of radioiodine from water by multistage isotope exchange between iodide and molecular iodine in a heterogeneous
liquid system under both static and dynamic conditions has been studied in two model arrangements. Equations were derived
which enable the calculation of the theoretical separation efficiency in dependence on both the volume concentration and concentration
of the carrier of radioiodide in water. It was found that under the same conditions, the calculated values are in a satisfactory
agreement with experimentally determined values of the separation efficiency. 相似文献
85.
The effect of cigarette smoke in air on the increase of the measured equivalent volume activity of222Rn is demonstrated. After introduction of the smoke from one cigarette into 1 m3 of air, this value increased up to ten times as shown by the method of sucking air through a filter. 相似文献
86.
Jesenák K. Kubinec R. Kuchta Ľ. Fajnor V. Š. 《Journal of Thermal Analysis and Calorimetry》2002,67(1):207-211
Thermal treatment of SiO2-aerogel in inert atmosphere, in contrary to oxidizing atmosphere, yields a series of gas products with great range of mole masses (12–154 g mol–1) and every product has specific way of evolving. These substances are represented by CO, CO2, CH4, CH3OH, C2H6, C2H4 and aromates. Part of evolving products, which are formed during catalytic condensation, is trapped under the surface and after carbonisation it causes opacity of surface layer of aerogel.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
87.
Š. Lányi 《Journal of Non》1982,47(3):403-416
The electrical properties of V2O5P2O5 glass-electrode interfaces have been investigated. Gold, graphite and aluminium, in that order, form contacts of increasing resistance. The dependence of barrier height on the work function of the electrode material is not consistent with the concept of Schottky barriers at the interfaces. The phenomenon may be explained by the downward bending and filling of a narrow band normally situated in the vicinity of the Fermi level, caused by injection of electrons from the less noble metals. This gives rise to a surface layer, which can, in principle, be insulating. However, alternative mechanisms, in the case of the investigated glasses most probably a Poole-Frenkel type field enhanced conduction via separated traps, lead to finite interface resistance. 相似文献
88.
We present a study of the temperature dependence of the critical currentJ
c of several dc magnetron sputtered thin Y-Ba-Cu-O films on single crystalline SrTiO3, ZrO2 and Al2O3 substrates. Near the critical temperature Tc it is found thatJ
c(1–T/Tc)n withn=3 for the SrTiO3 and ZrO2 substrates, whilen=1·3 for the Al2O3 substrate. The temperature dependence in our samples approximately agrees with standard theories for weak links or with the Ambegaokar-Baratoff equation. 相似文献
89.
Š. Palágyi 《Journal of Radioanalytical and Nuclear Chemistry》1989,131(2):271-279
Theoretical possibilities of the preconcentration of solutes in multistage static liquid-liquid extraction have been investigated. It was found that the preconcentration increases with increasing distribution ratio of the solutes between two phases as well as with the number of stages (n) and reaches its maximum value for n approaching infinity, i.e., in dynamic extraction. Comparison of the preconcentration in multistage (Pns) and one-stage (p1s) static operations shows that the relative preconcentration (qns=pns/p1s) increases to infinity as the separation efficiency approaches 100%. Some of these theoretical considerations have been confirmed in extraction of radioiodine from aqueous solutions.Presented at the 2nd International Conference on the Separation of Ionic Solutes, SIS'87, Smolenice, Czechoslovakia, October 12–15, 1987. 相似文献
90.
Š. Palágyi 《Journal of Radioanalytical and Nuclear Chemistry》1976,29(2):271-285
A rapid and specific method for the determination of131I in environmental water samples in the presence of some of the most important fission products is described. Radioiodine
is separated from acidified water using tri-n-octylamine solution in toluene with dissolved iodine by one-stage static procedure
with about 90% separation efficiency and 200-fold volume concentration. After the decolorization of the organic phase with
NaOH in methanol, radioactivity of131I is counted by a toluene base liquid scintillator with a counting efficiency of 70%. The method is simple and enables to
determine low radioactivity131I with a detection limit less than 5 pCi/1 in about 1.5 hrs. 相似文献