Numerical solution of moisture,salinity, and heat transport problem in the aeration zone

A numerical example of the salinity regime of soils in a two-dimensional region is considered with allowance for the effect of temperature fields. The mathematical model is based on solving a system of nonlinear partial differential equations.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 60, pp. 59–65, 1986.     

Effects of neutron skin on the excitation of isovector modes of neutron-rich nuclei

The existence of a neutron skin in neutron-rich nuclei is discussed in connection with the excitation of isovector dipole and quadrupole giant modes via isoscalar nuclear probes. In the case of large neutron excess, important contributions are obtained from the nuclear excitation, which may even become predominant according to proper kinematical conditions. At variance with the usual situation encountered in inelastic processes, constructive interference can be found between nuclear and Coulomb contributions.     

The application of the Mössbauer spectroscopy for the study of the contaminants in the double circuit water heat-carrier nuclear power plant

The iron containing corrosion products from water heat-carrier and deposits of the second circuit of the nuclear power plant were investigated by means of absorption Mössbauer spectroscopy. The nonstoichiometric magnetite and paramagnetic (superparamagnetic) iron oxide particles were found to be the main corrosion products. The fraction of the magnetically ordered phase varied in the range 0–100% depending on the location in the second circuit.     

μSR studies of heavy fermion systems

We have performed both zero field and high transverse field measurements at dilution refrigerator temperatures on a number of heavy electron systems, examining the superconducting and magnetic properties of these interesting materials. Among the materials studied to date are UBe₁₃, URu₂Si₂ and U₆Fe. The magnetic field penetration depth in the superconducting state of UBe₁₃ is greater than 10000 Å, as no increase in the transverse field relaxation rate is observed belowT _c . A sharp increase in the precession frequency is seen, starting atT _c . This frequency shift shows little temperature dependence at low temperature; we found no clear evidence for unconventional superconductivity in this material. Zero field measurements in URu₂Si₂ show the weak antiferromagnetic transition at 17.5 K. Finally, we we found no clear evidence for unconventional superconductivity in this material. Zero field measurements in URu₂Si₂ show the weak antiferromagnetic transition at 17.5 K. Finally, we have observed relaxation in high transverse field due to the formation of a flux lattice in U₆Fe, a material where the electron effective mass is rather lighter than in other heavy fermion systems. The relaxation exhibits a sharp onset atT _c=3.9 K, and is flat at low temperatures as expected for a conventional superconductor.     

An automated laboratory EXAFS spectrometer of Johansson type: indigenous development and testing

An automated linear laboratory EXAFS spectrometer of the Johansson type has been indigenously developed. Only two translational motions are required to achieve the necessary Rowland circle configuration for the (fixed) X-ray source, the dispersing and focusing bent crystal and the receiving slit. With the available crystals the spectral region from 5 to 25 keV can be scanned. The linear motions of the crystal and receiving slit including the detector assembly are achieved by employing software-controlled DC motors and utilizing optical encoders for position sensing. The appropriate rotation of the crystal is achieved by the geometry of the instrument. There is a facility to place the sample alternately in the path of the X-ray beam and out of the path to record both the incident X-ray intensityI ₀ and the transmitted intensityI employing the scintillation detector. An arrangement with a two-window proportional detector before the sample to measureI ₀ and the scintillation detector to recordI is also developed; in this case it is not necessary to oscillate the sample. Fast electronic circuits are employed to minimize counting errors. The instrument is user-friendly and it is operated through a menu-driven IBM compatible PC. EXAFS spectra of high resolution have been recorded using the spectrometer and employing the Si(111) reflecting planes; the X-ray source being a Rigaku 12 kW rotating anode with Cu target. We describe the spectrometer and discuss its performance with a few representative spectra.     

Radiation heterogeneous processes of14C-acetic acid adsorbed in Na-Montmorillonite

This research addresses itself to the study of the mechanism of the acetic acid decarboxylation in Na-Montmorillonite exposed to ionizing radiation. The results obtained indicated that the decarboxylation reaction is enhanced several times by the irradiation. This behavior is probably due to an oxidation reaction at the edges of the clay. Also it is by energy transfer from the clay to adsorbed molecules by an interaction of non-equilibrium charge carriers with the adsorbed molecules.     

Deformations of complex structures on Γ/SL 2(C)

LetG be a connected complex semisimple Lie group. Let Γ be a cocompact lattice inG. In this paper, we show that whenG isSL ₂(C), nontrivial deformations of the canonical complex structure onX exist if and only if the first Betti number of the lattice Γ is non-zero. It may be remarked that for a wide class of arithmetic groups Γ, one can find a subgroup Γ′ of finite index in Γ, such that Γ′/[Γ′,Γ′] is finite (it is a conjecture of Thurston that this is true for all cocompact lattices inSL(2, C)). We also show thatG acts trivially on the coherent cohomology groupsH ⁱ(Γ/G, O) for anyi≥0.