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961.
Electron spin resonance (ESR) study was done on calcite encrustation on Fili neotectonic fault surface, Greece. Normally such
calcite encrustations on fault surfaces are not observed. Significantly, the ESR study has detected the presence of nitrate
NO32− radical in this calcite encrustation, havingg
⊥=2.0063±0.0001 and hyperfine coupling constantA
⊥=3.44 mT, the second such detection of nitrate NO32− radical following a sample from Scott Glacier, Antarctica. From isochronal thermal annealing measurement the NO32− radical was found to be quite stable, only fully annealed at 475°C. This study also shows that the ESR, as a tool, can be
suitably applied to date the age of formation of the calcite encrustation with SO3− as an ESR dating signal by additive γ-ray irradiation. A preliminary estimation indicates the age of formation of calcite
precipitation at Fili fault, Greece to be about 5600 years. 相似文献
962.
E. Rodriguez E. Jimenez G.J. Jacob A.A.R. Neves C.L. Cesar L.C. Barbosa 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):361
Multilayer PbTe quantum dots (QDs) and SiO2 were grown by pulsed laser deposition (PLD) and Plasma enhanced chemical vapor deposition (PECVD) techniques. The crystalline structure, QD size and size dispersion were observed by high-resolution transmission electron microscopy (HRTEM) measurements. This technique allows one to grow PbTe QDs as small as 1.8 nm diameter and 0.6 nm size dispersion. The whole structure can be used in a Fabry–Perot cavity for an optical device operating at the mid-infrared region. 相似文献
963.
A switching of the S-type in the 20–200 μm thick polycrystalline n-CdTe:In layers with resistance of 103–106 Ω·cm is studied. The electric instability in the layers is found to be due to the electron-thermal breakdown mechanism. The
dependence of the switching threshold parameters on the intensity of exposure can be used for fabrication of infrared-radiation
controlled electric switches on the basis of n-CdTe:In layers.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 28–30, June, 2005. 相似文献
964.
S. V. Semikolenov K. A. Dubkov E. V. Starokon' D. E. Babushkin G. I. Panov 《Russian Chemical Bulletin》2005,54(4):948-956
The kinetics and mechanism of noncatalytic liquid-phase oxidation of but-1-ene and but-2-ene with nitrous oxide in a benzene
solution in the temperature range from 180 to 240°C were studied. Oxidation proceeds via the 1,3-dipolar cycloaddition mechanism to form carbonyl compounds. Both of these reactions occur with close rates and activation
energies and have the first orders with respect to the alkene and N2O. A considerable fraction (39%) of but-1-ene involved in oxidation undergoes cleavage at the double bond yielding propanal
and an equivalent amount of methylene, the latter producing ethylcyclopropane and cycloheptatriene. The oxidation of but-2-ene
proceeds with a minimum bond cleavage and affords methyl ethyl ketone with 84% selectivity. Regularities of the oxidation
of terminal and internal alkenes C2—C8 with nitrous oxide were analyzed using the previously published data.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 925–933, April, 2005. 相似文献
965.
966.
A method for preparing sulfate-oxalate chromium-plating solutions by reducing Cr(VI) from industrial chromium-plating electrolytes to Cr(III) with a Na2SO3 solution is proposed. 相似文献
967.
We consider the differential operators Ψ
k
, defined by Ψ1(y) =y and Ψ
k+1(y)=yΨ
k
y+d/dz(Ψ
k
(y)) fork ∈ ℕ fork∈ ℕ. We show that ifF is meromorphic in ℂ and Ψ
k
F has no zeros for somek≥3, and if the residues at the simple poles ofF are not positive integers, thenF has the formF(z)=((k-1)z+a)/(z
2+β
z+γ) orF(z)=1/(az+β) where α, β, γ ∈ ℂ. If the residues at the simple poles ofF are bounded away from zero, then this also holds fork=2. We further show that, under suitable additional conditions, a family of meromorphic functionsF is normal if each Ψ
k
(F) has no zeros. These conditions are satisfied, in particular, if there exists δ>0 such that Re (Res(F, a)) <−δ for all polea of eachF in the family. Using the fact that Ψ
k
(f
′/f) =f
(k)/f, we deduce in particular that iff andf
(k) have no zeros for allf in some familyF of meromorphic functions, wherek≥2, then {f
′/f :f ∈F} is normal.
The first author is supported by the German-Israeli Foundation for Scientific Research and Development G.I.F., G-643-117.6/1999,
and INTAS-99-00089. The second author thanks the DAAD for supporting a visit to Kiel in June–July 2002. Both authors thank
Günter Frank for helpful discussions. 相似文献
968.
U.S. NaziaA.K.M.A. Islam 《Solid State Communications》2003,125(1):37-40
The Eliashberg spectral density function is constructed for the superconducting compound BaxK1−xBiO3 with x=0.5, 0.6, 0.7. The functions, besides yielding some prominent structures, show widely spreading spectra that inhibit lattice instability by yielding not too large values of λ(<1.32). The resulting spectral functions show similar shape as other results, where available, and also successfully reproduce the observed critical temperature, isotope exponent, gap ratio and several other parameters. 相似文献
969.
970.
Results of studying electro-optic size effects and nonlinear electro-optic effects in ferroelectric PLZT ceramics are presented. It is established that the presence of electro-optic size effects makes microvolume samples of PLZT ceramics promising for designing efficient modulating devices. 相似文献