bluuebunny/crossref_metadata_2025 huggingface dataset:
Certain Problems with the Application of Stochastic Diffusion Processes for the Description of Chemical Engineering Phenomena. Diffusional Change of Solid Particle Size
Authors: Kudrna Vladimír , Hasal Pavel
Published: July 2002

To the description of changes of solid particle size in population, the application was proposed of stochastic differential equations and diffusion equations adequate to them making it possible to express the development of these populations in time. Particular relations were derived for some particle size distributions in flow and batch equipments. It was shown that it is expedient to complement the population balances often used for the description of granular systems by a "diffusion" term making it possible to express the effects of random influences in the growth process and/or particle diminution.
Activity Coefficients of Aqueous Solutions of NaOH and KOH in Wide Concentration and Temperature Ranges
Authors: Balej Jan
Published: July 2002

Up to now, there exist a quite wide temperature interval between 70 or 80 and 150 °C with no sufficiently reliable experimental data of mean activity coefficients for aqueous NaOH as well as KOH solutions. In order to fill this gap, it was tried to derive suitable correlation equations for this quantity in dependence on the molality (for NaOH in the range mNaOH = 2-25 mol kg-1, for KOH in the range mKOH = 2-18 mol kg-1) and temperature (in the range 0-200 °C for both kinds of solutions) on the basis of the available data of this quantity and with the use of the previously derived correlation equations for the water activity in aqueous solutions of NaOH and KOH under the same conditions. The comparison between the calculated and experimental data was discussed.
The Thermodynamics of Solid Solutions of Ni(II)/Ni(IV) Oxo Compounds
Authors: Balej Jan , Divisek Jiri
Published: July 2002

The measured data of equilibrium and rest potentials of higher nickel oxo compounds, E' (converted for 25 °C and aH2O = aKOH = aH2 = 1.0) selected in the range of the overall oxidation number of 2.0 < zNi ≤ 3.6, were newly evaluated with the aid of a simplified model of the quasi-binary solid solutions Ni(OH)2/Ni(OH)4 assuming unlimited miscibility. It was found that the dependence of E' on the composition of the redox system can be described by a Nernst equation in the entire range of zNi investigated, where the activity coefficients of individual components are expressed by relations for regular solutions. The so calculated activities of considered components showed positive deviations from the ideal behaviour of the solid solutions. All results obtained were discussed in more detail assuming the non-existence of Ni(III) oxo compounds in such solid solutions.
Effectiveness Factor for a Non-Isothermal Simple Catalytic Reaction with Combined Transport Processes: Maxwell-Stefan Approach
Authors: Schneider Petr
Published: July 2002

A two-step procedure is developed and tested for the prediction of effectiveness factors for stoichiometrically simple catalytic reactions. In the first step the dependences of state variables (concentrations, temperature, pressure) on the concentration of the key reaction component is obtained. The knowledge of these dependences allows then all the dependent variables in the catalyst pellet mass and heat balances to be expressed by this concentration. In the second step, a single balance differential equation is solved and the effectiveness factor is obtained. In addition, a deeper insight into the concentration and temperature conditions inside the pores is gained. Information of this kind can cast light on some features of the catalytic reactor behaviour. The analysis of ammonia synthesis illustrates this point.
Macroscopic-Microscopic Paradox in Dynamic Equilibrium Focusing
Authors: Janča Josef
Published: July 2002

Recent theoretical and experimental findings concerning equilibrium focusing in density gradient (isopycnic focusing) indicate that the density gradient forming liquid should not necessarily behave as a continuum regarding the focused species. The size of the focused species can be commensurate with the size of the density gradient forming species. Consequently, the microscopic interactions among the gradient forming and focused species must be taken into account while the macroscopic density gradient loses its physical meaning with regard to the mechanism of the focusing. As a result, a paradox appears as concerns the macroscopic and microscopic approaches to explain the focusing phenomenon.
Ionic Processes in Saturated Solutions of MgCl2·6H2O in Solutions of Other Divalent Metals
Authors: Eysseltová Jitka
Published: July 2002

Solubility isotherms of MgCl2·6H2O at 25 °C in solutions of chlorides of bivalent beryllium, calcium, manganese, iron, cobalt, zinc and mercury were treated by the hydration analysis. In addition to the usual procedure, the recently developed modified transfer energy Ξ was used to characterize the situation in saturated solutions. As a result, the following ionic processes were established in the saturated solutions under consideration: competition for water in solutions of MgCl2·6H2O containing beryllium and calcium chloride, complex formation in solutions of MgCl2·6H2O containing manganese, cobalt, zinc and mercury ions and formation of ions with heterogeneous coordination sphere in solutions of MgCl2·6H2O containing iron or copper ions. In the last case, the ability of the formed ions to crystallize from solution was found to be reduced in comparison with the other cases. Activity coefficients of MgCl2 were calculated along the solubility curves under consideration.
Electrosynthesis of Electroactive Metal-Metal Bonded Polymers [Ru(CO)2L]n (L = 2,2'-Bipyridine Derivatives), Their Characterization and Catalytic Activity. A Review
Authors: Chardon-Noblat Sylvie , Deronzier Alain , Ziessel Raymond
Published: July 2002

This paper presents an account on the preparation, characterization and properties of conductive polymers [Ru(CO)2L]n (L = 2,2'-bipyridine derivatives). These strongly adherent and highly colored films containing Ru chains are unique examples of a new generation of organometallic polymers that possess interesting catalytic properties. The formation of these materials from mononuclear complexes like [RuCl2(CO)2L] and their properties were investigated by combined electrochemical techniques and UV-VIS, NMR, FTIR and EPR spectroscopies. The polymer is produced by electrochemically induced propagation involving the intermediate formation of dimers, tetramers and higher oligomers. The air sensitivity of this kind of Ru(0) polymers can be overcome by using polypyrrole matrix with L-attached mononuclear [RuCl2(CO)2L] precursor complexes. A following cathodic step leads, within the polypyrrole film, to the intended second polymer with Ru-Ru bonds. The morphology of this unusual hybrid polymer, investigated by scanning electron microscopy, revealed a uniform material. Regular films are formed by electrodeposition on carbon fibers. Most of these polymers possess high and selective catalytic activity in the electroreduction of carbon dioxide in aqueous media. A review with 36 references.
Coumarin 6, Hypericin, Resorufins, and Flavins: Suitable Chromophores for Fluorescence Correlation Spectroscopy of Biological Molecules
Authors: Beneš Martin , Hudeček Jiří , Anzenbacher Pavel , Hof Martin
Published: July 2002

In this work we show that the dyes coumarin 6, hypericin, 7-O-ethylresorufin and resorufin are suitable for fluorescence correlation spectroscopy (FCS) and demonstrate the use of these dyes in physiologically relevant protein studies. Since coumarins are metabolised by cytochromes P450, the binding of coumarin 6 to cytochrome P450 3A4 was investigated by FCS. Coumarin 6 appears to be a very bright non-covalent cytochrome P450 label. When titrating cytochrome P450 3A4 with coumarin 6, the diffusion time of the coumarin 6/ cytochrome P450 3A4 complex increases roughly two-fold at protein concentrations higher than 1 μmol l-1, indicating the formation of cytochrome aggregates. FCS of the flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) shows that both endogenous dyes undergo photobleaching. Moreover, FAD appears to be present to great extent, as a non-fluorescent intramolecular complex. Analysis of the FCS data of the flavoprotein NADPH-cytochrome P450 oxidoreductase (molecular weight 76 500) yielded two components. While the slow component corresponds to a globular protein with the molecular weight about 75 000, the fast component appears to be due to free diffusing FMN and FAD molecules. The amount of free FMN and FAD increases with increasing laser power. At high laser power a complete photodissociation of FMN and FAD occurs.
[(Dimethylamino)methyl]ferrocene as an Amine Ligand: Study of the Bonding and X-Ray Crystal and Molecular Structure of the Pentacarbonyl{[(dimethylamino)methyl]ferrocene}tungsten Complex
Authors: Fischer Axel , Edelmann Frank T. , Jacob Klaus , Pavlík Ivan , Pavlišta Martin
Published: July 2002

The heterodinuclear complex [W(CO)5(Me2NCH2Fc)] (Fc = ferrocenyl) (1) resulting from the reaction of [(dimethylamino)methyl]ferrocene (2) and [W(CO)6] was studied by single-crystal X-ray diffraction. Its molecular structure confirms the coordination of the amine nitrogen in 2 to tungsten (d(W-N) = 2.359(5) Å) and reveals its trans-influence in the W(CO)5 moiety. The structure is discussed in relation to several previously referred spectroscopic (IR, UV-VIS, 13C NMR) data.
Sarcoidosis 2001
Authors: James D Geraint
Published: July 2002

In every decade, sarcoidosis makes a chameleon-like change so its profile needs to be updated. It was first recognised as a dermatological curiosity which evolved into a multisystem disorder with bone cysts, uveitis, and intrathoracic involvement. New dimensions were uncovered by biochemistry and immunology, bringing it still nearer the elusive enigma, namely the cause of sarcoidosis. Aetiology includes an understanding of a genetic predisposition and environmental trigger factors. What was left undone in the 20th century will become evident in the 21st century with more sophisticated technology. Likewise, conventional treatments of the past will be superseded by cytokines and other magic bullets of the millennium.
Perméabilité in situ du béton de peau, établie à partir de la percolation d'un gaz en régime d'écoulement permanent
Authors: Perraton Daniel , Carter Alan , Vaillancourt Michel , Lavoie Bruno
Published: July 2002

In an attempt to apply the concepts developed by Carman and Klinkenberg for the measurement of permeability of a porous media using a gas, a permeameter for the in-situ measurement of intrinsic permeability of skin concrete has been developed. The established technique allows concentration of gas percolation through a well-defined zone in the superficial layer of concrete. The instrument, the measurement method, and the calculation procedure are described in details in this paper. Several series of tests have been performed in laboratory on concrete blocks (300 × 300 × 400 mm) to simulate measurements on the construction site. Three types of concrete, with different porosity, have been tested. The measurement of permeability performed on the concrete blocks have been accomplished both on shaped surfaces, which are representative of skin concrete, and on sawed surfaces, which are representative of mass concrete. Results show that the relationship between the water/cement ratio and the permeability of skin concrete varies distinctively compared with that of mass concrete. The permeameter allows quantification of what has been for a long time qualified as a determining element in terms of the durability of concrete against the corrosion of reinforcement, that is, the distinct permeability of skin concrete from that of mass concrete.Key words: skin concrete, in-situ permeability, intrinsic permeability, apparent permeability, permeameter, Klinkenberg.[Journal translation]
TWO CONP-COMPLETE SCHEDULE ANALYSIS PROBLEMS
Authors: Rhodes David L. , Wolf Wayne
Published: July 2002

While many forms of schedule decision problems are known to be NP-complete, two forms of schedule analysis problems are shown to be coNP-complete in the strong sense. Each of these involve guaranteeing that all deadlines are met for a set of task-graphs in statically-mapped, priority-based, multiprocessor schedules given particular variabilities. Specifically, the first of these allows run-times which axe bracketed, where the actual run-time of some tasks can take on any value within a given range. The second deals with task-graphs which arrive asynchronously, that is where the release-time for each task-graphs may take either any or a bracketed value. These variations correspond to task-graphs with either release-time or run-time jitter. The results are robust in the sense that they apply when schedules are either preemptive or non-preemptive as well as for several other problem variations.
JAUCH–PIRON STATES AND σ-ADDITIVITY
Authors: BUNCE L. J. , HAMHALTER JAN
Published: July 2002

We study σ-additivity of the physically plausible Jauch–Piron states on a von Neumann algebra M. Amongst other consequences we extend our earlier results [5] by showing that geometric conditions much weaker than pureness imply σ-additivity for a Jauch–Piron state and, further, that if M is properly infinite and the continuum hypothesis is assumed to be true then all Jauch–Piron factor states are σ-additive.
EXACT SOLUTIONS OF CONFORMAL FIELD THEORY IN TWO DIMENSIONS AND CRITICAL PHENOMENA
Authors: ZAMOLODCHIKOV A. B.
Published: July 2002

Modern development of conformal field theory in two dimensions and its applications to critical phenomena are briefly reviewed. The specific properties of the renormalization group in two dimensions and the fundamentals of 2-dimensional conformal field theory are presented. The properties of degenerate representations of the Virasoro algebra and other infinite dimensional algebras, "minimal" models of conformal and superconformal field theory, "parafermionic" and other symmetries are discussed. We also investigate a perturbation theory around conformal solutions of field theory.
ZERO-TEMPERATURE SKEWED CHIRAL POTTS MODEL
Authors: BAXTER R. J.
Published: July 2002

Functional relations have previously been obtained for the eigenvalues of the transfer matrices of the chiral Potts model. Introducing skewed boundary conditions is equivalent to merely modifying the quantum number of the spin shift operator in the relations (which accounts for at least some of the previously noted "spurious solutions"). As a first step towards calculating the general interfacial tension, we consider the model in a zero-temperature limit. It is still non-trivial, there being near-vertical free interfaces separating domains of different spin value. These interfaces behave like the "lines of down arrows" in the ice model, so one may hope to follow Lieb and use the Bethe ansatz to evaluate the partition function. It turns out that this can indeed be done. There is no wetting of an interface by intermediate phases.
CROSSED PRODUCT C*-ALGEBRAS AND ALGEBRAIC TOPOLOGY
Authors: PACKER JUDITH A.
Published: July 2002

We discuss some recent developments that illustrate the interplay between the theory of crossed products of continuous trace C*-algebras and algebraic topology, summarizing results relating topological invariants coming from the theory of fiber bundles to continuous trace C*-algebras and their automorphism groups and the structure of the associated crossed product C*-algebras. This survey article starts from the classical theory of Dixmier, Douady, and Fell, and discusses the more recent work of Echterhoff, Phillips, Raeburn, Rosenberg, and Williams, among others. The topological invariants involved are Čech cohomology, the cohomology of locally compact groups with Borel cochains of C. Moore, and the recently introduced equivariant cohomology theory of Crocker, Kumjian, Raeburn and Williams.
QUANTUM STOCHASTIC DYNAMICS II
Authors: MAJEWSKI ADAM W. , ZEGARLINSKI BOGUSLAW
Published: July 2002

We shortly review the progress in the domain of stochastic dynamics for quantum spin systems on a lattice. We also present some new results obtained in the framework of noncommutative [Formula: see text] spaces. In particular, using noncommutative Radon-Nikodym theorem of A. Connes we construct Markov generators of stochastic dynamics of spin flip type for systems at high temperatures or on one-dimensional lattice and with interactions of finite range at arbitrary temperatures.
QUANTUM FIELD THEORIES ON NULL SURFACES
Authors: GUPTA KUMAR S. , YDRI BADIS
Published: July 2002

We study the behavior of quantum field theories defined on a surface S as it tends to a null surface Sn. In the case of a real, free scalar field theory the above limiting procedure reduces the system to one with a finite number of degrees of freedom. This system is shown to admit a one parameter family of inequivalent quantizations. A duality symmetry present in the model can be used to remove the quantum ambiguity at the self-dual point. In the case of the nonlinear σ-model with the Wess–Zumino–Witten term a similar limiting behavior is obtained. The quantization ambiguity in this case however cannot be removed by any means.
CASIMIR FORCE UNDER THE INFLUENCE OF REAL CONDITIONS
Authors: GEYER B. , KLIMCHITSKAYA G. L. , MOSTEPANENKO V. M.
Published: July 2002

The Casimir force is calculated analytically for configurations of two parallel plates and a spherical lens (sphere) above a plate with an account of nonzero temperature, finite conductivity of the boundary metal and surface roughness. The permittivity of the metal is described by the plasma model. It is proved that in case of the plasma model the scattering formalism of quantum field theory in Matsubara formulation underlying Lifshitz formula is well defined and no modifications are needed concerning the zero-frequency contribution. The temperature correction to the Casimir force is found completely with respect to temperature and perturbatively (up to the second order in the relative penetration depth of electromagnetic zero-point oscillations into the metal) with respect to finite conductivity. The asymptotics of low and high temperatures are presented and contributions of longitudinal and perpendicular modes are determined separately. Serving as an example, aluminium test bodies are considered, showing good agreement between the obtained analytical results and previously performed numerical computations. The roughness correction is formally included and formulas are given permitting us to calculate the Casimir force under the influence of all relevant factors.
VACUUM RESPONSE TO ELECTROMAGNETIC BACKGROUNDS
Authors: ACTOR A. A.
Published: July 2002

We investigate the vacuum state of a charged scalar field [Formula: see text] coupled to two different electromagnetic (EM) backgrounds on two different spaces.

(i) [Formula: see text] is first defined on cylindrical space E2 × S1 with compact direction z ∈ S1 having circumference L3. This spatial compactification enables (but does not compel) an EM vacuum density j3 to flow around the spatial cylinder, parallel to z. However, a nonzero gauge potential A3 prefers one direction around z over the other, causing j3 to become nonzero. We analyze this situation for A3 = A3 (y) an arbitrary function of coordinate y, with A0,1,2 = 0.

(ii) [Formula: see text] is next defined on Minkowski spacetime in the presence of a background EM plane wave of arbitrary shape and amplitude. As the plane wave sweeps through the charged virtual particle sea at the speed of light it locally excites or churns the sea, making the vacuum nonstationary (without producing vacuum pairs). This nonstationary excitation of the vacuum is nondissipative. A summary of recent calculations is presented.

These two examples clearly display that, in gauge theory, potentials are more fundamental then fields.
PHASE STABILITY OF BCC TRANSITION METALS: ROLE OF d-ELECTRONS
Authors: HUSSEIN ABDULLAH M. , RAHMAN S. M. MUJIBUR
Published: July 2002

The role of d-electrons in the structural phase stability of bcc transition metals viz. V, Fe, Cr and Mn are investigated. The underlying theory expresses the relevant structural part of the free energy in terms of the repulsion of the d-electron muffin-tin orbitals assigned to atomic sites and the attractive contribution arising from the band broadening effects of the d-bands in the total energy. The magnetic contribution arising from the population of magnetic moments in the systems is also included in the theory. The d-electronic contribution to entropy is written in terms of the density-of-electronic states at the respective Fermi level. The phase stability of the bcc transition metals is explained in terms of the population of atoms on the local and extended sites. It is observed that the d-electron energetics can precisely and correctly predict the crystal structure of the bcc transition metals.
POLARON ORDERING IN FERROMAGNETIC COLOSSAL MAGNETORESISTIVE OXIDES
Authors: VASILIU-DOLOC L. , OSBORN R. , ROSENKRANZ S. , MESOT J. , MITCHELL J. F. , SINHA S. K. , SEECK O. H. , LYNN J. W. , ISLAM Z.
Published: July 2002

We review our recent x-ray and neutron scattering studies that reveal static diffuse scattering due to polarons in the paramagnetic phase of the colossal magnetoresistive manganites La 2-2x Sr 1+2x Mn 2 O 7, with x=0.40 and 0.44. We show that the polarons exhibit short-range incommensurate correlations that grow with decreasing temperature, but disappear abruptly at the combined ferromagnetic and metal-insulator transition in the x=0.40 system because of the sudden charge delocalization, while persisting at low temperature in the antiferromagnetic x=0.44 system. The "melting" of the polaron ordering as we cool through TC occurs with the collapse of the polaron scattering itself in the x=0.40 system. The polaron order is characterized by an ordering wave vector q=(0.3,0,1) that is almost independent of x for x≥0.40, and is consistent with a model of disordered stripes.
QUASI-CLOSURE AND SCALING OF TURBULENCE
Authors: QIAN J.
Published: July 2002

A statistically stationary isotropic turbulence is of quasi-closure, i.e. its high-order statistical moments can be derived from its low-order moments. A workable quasi-closure scheme is developed for the structure functions of incompressible homogeneous isotropic turbulence based upon a non-Gaussian statistical model. The second order structure function is obtained by solving the spectral dynamic equation or by using an empirical formula such as the Batchelor fit, and then the high-order structure functions is calculated by the quasi-closure scheme. We study the absolute and relative scaling of the structure functions of isotropic turbulence in connection with Kolmogorovs' 1941 theory (K41) and his 1962 theory (K62). In contrast to K62 and various intermittency models, our results suggest a different picture of scaling of isotropic turbulence: the anomalous scaling of structure functions observed in experiments and numerical simulations is a finite Reynolds number effect, and the K41 normal scaling is valid in the real Kolmogorov inertial range corresponding to an infinite Reynolds number.
RENORMALIZATION GROUP APPROACHES TO STRONGLY CORRELATED ELECTRON SYSTEMS
Authors: HEWSON A. C. , BRADLEY S. C. , BULLA R. , ŌNO Y.
Published: July 2002

In recent years the numerical renormalization group (NRG) method has been extended to the calculation of dynamic response functions and transport properties of magnetic impurity models. The approach can now be applied more widely to lattice models of strongly correlated electron systems by the use of dynamical mean field theory (DMFT), in which the lattice problem is transformed into one for an effective impurity with an additional self-consistency constraint. We review these developments and assess the potential for further applications of this approach. We also discuss an alternative approach to renormalization, renormalized perturbation theory, in which the leading asymptotically exact results for the low temperature regime for a number of magnetic impurity models can be obtained within finite order perturbation theory.
RESONANT RAMAN SCATTERING OF INTERACTING TWO-CHANNEL QUANTUM WIRES
Authors: LEE HYUN C.
Published: July 2002

Resonant Raman scattering of degenerate interacting two-channel quantum wire is studied. All collective excitations of two-channel quantum wire are shown to give rise to peaks in the polarized Raman spectra near resonance. If there exist certain symmetries among interactions, a resonant peak can also appear in the depolarized Raman spectra, in contrast to the single-channel case studied by Sassetti and Kramer. We also calculate the explicit form of the scattering cross-section away from the peaks. The above features may be experimentally verified in armchair carbon nanotube systems.
FABRICATION OF 2- AND 3-DIMENSIONAL NANOSTRUCTURES
Authors: Jiang Hong , Borca Camelia N. , Xu Bo , Robertson Brian W.
Published: July 2002

Amongst tools for fabricating periodic and aperiodic nanostructures and nanodevices, electron beam-induced organometallic chemical vapor deposition (E-OMCVD) offers a highly flexible and controllable one-step deposition process. E-OMCVD enables maskless fabrication of nanoscale research and custom structures that have least dimensions near or below 10nm – a scale at which other methods prove difficult or costly. Using the focused electron beam in a modified HB501 field-emission scanning transmission electron microscope (STEM), pads and wires with uniform thickness and well-defined shapes have been defined and deposited. Although conditions for fabricating the smallest deposits have not yet been optimized, the edge acuity (sharpness) of the deposits is consistently as low as 4nm or less and the corresponding smallest wire width is 8nm. Under different deposition conditions, three-dimensional open structured nanonetworks have been fabricated. Results of an investigation of E-OMCVD parameters are presented for the metallocene compound, nickelocene (Ni(C5H5 )2), as source organometallic.
GIANT TWO-PHOTON ABSORPTION INTO EXCITED STATES OF BIEXCITON
Authors: DMITRUK I. , KASUYA A. , GOTO T. , YANCHUK Z.
Published: July 2002

Excited states of excitonic molecule have been observed for the first time by direct method of giant two-photon absorption in monoclinic ZnP 2 single crystal. Two excited states with binding energies 3.3 meV and 1.9 meV have been observed in absorption spectra of intense picosecond laser pulses. First one corresponds to rotational excited state. Interpretation of the second one and details of nonlinear absorption spectra are discussed.
STRUCTURAL AND OPTICAL PROPERTIES OF NANOCRYSTALLINE SILICON FILMS DEPOSITED AT 150°C
Authors: ALI ATIF MOSSAD , SAKAI YASUHIKO , ADACHI NOBORU , INOKUMA TAKAO , KURATA YOSHIHIRO , HASEGAWA SEIICHI
Published: July 2002

Nanocrystalline silicon (nc-Si) films were deposited by plasma-enhanced chemical vapor deposition from a SiH 4- H 2 gas mixture. The structural and optical properties of nc-Si films were examined by changing the flow rates of a H 2 gas or a SiF 4 gas diluted by He. The structural change from an amorphous to a nanocrystalline phase was found at H 2 flow rate ([ H 2]) higher than 3 sccm under [ SiF 4/ He ] = 0 sccm and/or by adding SiF 4/ He under [ H 2] = 0 sccm . However, under [ H 2] = 3 sccm, the maximum crystallinity (crystalline volume fraction, ρ) was observed at around [ SiF 4/ He ] = 2 sccm . The photoluminescence exhibited two peaks at around 1.7 eV and 2.2 - 2.3 eV. The first 1.7-eV-peak may be related to nanocrystallites in nc-Si films and the origin of another 2.2 - 2.3-eV-peak is not clear. Thus, hydrogen and fluorine appear to play different role in the crystallization process. In addition, under [ H 2] = 0 sccm , we found a close correlation among the increases in the ρ and the average grain size values and the SiH 2 density with increasing [ SiF 4/ He ].
EFFECTS OF CORRELATIONS AND DISORDER IN QUANTUM WIRES
Authors: NEILSON D. , THAKUR J. S.
Published: July 2002

We calculate electron-electron correlation effects in a one-dimensional electron liquid at low densities using the self-consistent scheme of Singwi, Tosi, Land and Sjölander (STLS). We determine the static structure factor S(q) and plasmon dispersion ω pl (q) for different electron densities. We also include the effects of disorder and calculate the dependence of correlation effects on the electron scattering rate off disorder. Using the scattering rate γ we determine transport properties like the mean-free path, the peak mobility and the boundary between weak and strong localisation phases. We note a relation between the peak mobility and this boundary.
STRONG COUPLING APPROACH TO ONE-DIMENSIONAL HUBBARD MODEL AND RELATED LATTICE MODELS
Authors: SHIBA H. , PENC K. , MILA F.
Published: July 2002

The strong coupling limit of one-dimensional correlated systems is nontrivial, but simple in some sense. Here we demonstrate it, discussing the wave functions for the 1D U→ +∞ Hubbard model, which are factorized as a direct product of the charge part and the spin part and determining the one-particle spectral functions explicitly.
Spatial Distribution of Superconducting Properties of High Rate Directionally Solidified YBCO Samples
Authors: Vecchione A. , Polichetti M. , Gombos M. , Pace S.
Published: July 2002

We report on spatial distribution of structural and superconducting properties in directionally solidified YBCO samples. The recrystallization process of produced YBCO bar was determined by a motion into a horizontal furnace at very high pulling rate in a fixed thermal gradient. Texturing and stoichiometry of several slices cut from the original bar have been studied by XRD and SEM with coupled EDS analysis. The magnetisation cycles of all the slices (M(H) Loops) were obtained by means a Vibrating Sample Magnetometer at 70 K using applied magnetic fields up to 2 tesla.
PHASE TRANSITION IN A FERROELECTRIC PLATE: POSITIVE SURFACE ENERGY AND SIZE EFFECT STUDY
Authors: PARK YUNG
Published: July 2002

This paper is no longer available. Please contact "ijmpb@wspc.com"
MAGNETIC SUSCEPTIBILITY OF THE RELATIVISTIC ELECTRON GAS
Authors: HOMORODEAN LAUREAN
Published: July 2002

The magnetic susceptibilities of the degenerate and nondegenerate relativistic electron gases, and of the nondegenerate electron–positron gas are presented.
POLARONIC EFFECT IN MATERIALS WITH FERROELECTRIC PHASE TRANSITIONS
Authors: MALOZOVSKY Y. M. , FAN J. D. , BAGAYOKO D. , WANG J. T.
Published: July 2002

We studied polaron effects due to the interaction of an electron with optical phonons in ferroelectrics with a layered crystal structure. We evaluated the polaron self-energy using the effective T-matrix. We showed that transition from the large radius polaron to the small radius polaron is controlled by the interlayer interaction or interlayer spacing. We also found that the polaron interaction with the fluctuations of polarizability near the Curie temperature causes polaron localization.
PHYSICAL CHARACTERIZATION OF PURE AND SUBSTITUTED TETRAGONAL LaBaCaCu3O7-δ SUPERCONDUCTOR
Authors: AWANA V. P. S. , NARLIKAR A. V.
Published: July 2002

The high T c superconductor, forming the focus of the present review, presents an interesting situation where, despite its oxygen content close to 7.0, the system prefers to crystallize in tetragonal structure, as distinct from exhaustively studied orthorhombic RE:123 ( REBa 2 Cu 3 O 7, RE = rare earth) compounds. Its optimum T c is decided by the cation intermixing at various sites, unlike that in case of normal RE:123, where all cationic sites are fully occupied and fixed, leaving the anionic sites free for oxygen filling. In this, we review the rich crystal chemistry of this compound and discuss it in conjunction with its unusual superconducting properties. The article is divided in five parts: (1) first we discuss variously reported interesting finer structural details and superconductivity of pristine LaBaCaCu 3 O 7-δ (La:1113) superconductor. The La, Ba and Ca sites are found to be intermixed with respect to their nominal sites of the standard RE:123 structure. (2) We examine the structural aspects and superconductivity of La 1-x RE x BaCaCu 3 O 7 (RE = Nd, Dy, Sm and Pr). Unlike RE:123 and 124 compounds, the RE:1113 compounds form only with light rare earths such as La, Pr and Nd. Pr:1113 compound is found to be an insulator with Pr moments ordering magnetically at around 8 K, unlike at 17 K for Pr:123. (3) Studies of Pr substitution reveal that relative T c depression due to Pr in the (La,Nd) 1-x Pr x BaCaCu 3 O 7 system is less in comparison to that found for La or Nd site Pr substituted (La,Nd) 1-x Pr x Ba 2 Cu 3 O 7. (4) The results of superconductivity and structural details are reviewed for LaBaCaCu 3-x M x O 7 (M = Fe, Co, Ni, Ga and Zn) and finally (5) we summarize our conclusions. The results in terms of T c depression due to these impurities in the parent La:1113 system are seen as similar to those observed for RE:124 ( REBa 2 Cu 4 O 8) and Nd:214 ( Nd 2-x Ce x CuO 4), but are different from RE:123 and La:214. The results of structural details, superconductivity and magnetic ordering presented in the four parts for La 1-x RE x BaCaCu 3-y M y O 7 (RE = Nd, Dy, Sm, Pr with 1.0 ≥ x ≥ 0.0, and M = Fe, Co, Ni, Ga and Zn with 0.24 ≥ y ≥ 0.0 were obtained from X-ray and neutron diffraction and using AC and DC magnetic susceptibility, electrical resitivity and heat capacity data as a function of temperature. This review is mainly a consolidated work of the authors, including their collaboration from various laboratories and the reported data of other workers, all being duly acknowledged in the text.
ORDERED VERSUS DISORDERED InGaP LAYERS GROWN BY LIQUID PHASE EPITAXY
Authors: PRUTSKIJ TATIANA A. , ARENCIBIA PEDRO DÍAZ , MINTAIROV ALEXANDER , MERZ JAMES , KOSEL THOMAS H.
Published: July 2002

We make a comparative study of the optical and structural characteristics of two InxGa1-xP(x≈0.5 ) films nearly lattice matched to GaAs, (here referred to as disordered type 1 sample (S1) and ordered type 2 sample (S2)). The films were grown by liquid phase epitaxy (LPE). Photoluminescence (PL) measurements were performed in a wide temperature and exciting power density range for different polarization of the emitted radiation along the [110] and [1-10] directions. Observations suggest that the InxGa1-xP layer in sample 1 is disordered, as commonly obtained in LPE growth, while in sample 2 at least a partially spontaneously ordered layer was obtained. Moreover, the energy position of the 20 K PL peak is close to the predicted band gap energy for the InGaP 2 material ordered in the CuPt phase. [1].
THE COMPLETE TREATMENT OF THE TIME EVOLUTION IN THE CASE OF A DISCRETIZED ATOM-FIELD INTERACTION MODEL
Authors: SEKE J. , SOLDATOV A. V. , BOGOLUBOV N. N.
Published: July 2002

The dynamics of a discretized atom-field interaction model with a physically relevant form factor is analyzed. It is shown that after some short time interval only a small fraction of eigenvalues and eigenstates (belonging to the close vicinity of the excited atomic state energy E = ω0/2) contributes to the nondecay probability amplitudes in the long-time regime, whereas the contribution of all other eigenstates and eigenvalues is negligible. Nevertheless, to describe correctly the non-Markovian dynamics in the short-time regime the contribution of all eigenstates and eigenvalues must be taken into account.
EXACT SOLUTION FOR A GENERAL SUPERSYMMETRIC QUADRATIC SYSTEM
Authors: LU HUAI-XIN , CHEN ZENG-BING , MA LEI , ZHANG YONG-DE
Published: July 2002

We construct a general supersymmetric quantum transformation for studying the supersymmetric quadratic Hamiltonian which contains the interaction of multi-mode fermions with multi-mode bosons. The Hamiltonian can be derived from that of multi-mode radiation field interacting with m two-level atoms. By using the supersymmetric quantum transformation, the diagonolized Hamiltonian is given. We also concisely derive the analytic expression of the super-partition function for the supersymmetric quadratic Hamiltonian without knowing the energy spectrum.
Multifractal Specific Heat of Disordered Mesoscopic Systems
Authors: Bershadskii A.
Published: July 2002

It is shown that multifractal data on critical behavior of wavefunctions at the Anderson metal–insulator transition obtained in numerical simulations are in good agreement with constant specific-heat multifractal approximation for three and two dimensional cases (in the last case in high magnetic field). A relation of this approximation to the parabolic multifractal approximation is also briefly discussed.
Dynamic Strain Conductivity of Compensated Silicon
Authors: Zainabidinov S. Z. , Mamatkarimov O. O. , Tursunov I. G. , Tuychiev U. A.
Published: July 2002

In this paper the strain thermal Hall effect has been investigated in initial n-Si(P) and strongly compensated n-Si(Ni) samples of different compensation degree, which have been subject to uniform hydrostatic compression (UHC) under a pulse pressure regime ranging from 0 to 7×108 Pa. An experimental investigation of the strain thermal effect in the n-Si(Ni) sample leads to an essential strain conductivity increase, which is largely controlled by density variations of majority carriers.
LOCAL FIELD FLUCTUATIONS IN THE MIXED SPINEL FERRITE, Ni1-xZnxFe2O4
Authors: TANG I. M. , VARAMIT S. , WIWATANAPATAPHEE B.
Published: July 2002

The magnetic properties of the mixed spinel ferrites Ni1-xZnxFe2O4 are studied with the framework of a mean field approach which takes into account the effects of random arrangements of the Zn and Fe ions in the A-sublattice and of the Ni and Fe ions in the B-sublattice. We are interested in the local field fluctuations which arise from these random arrangements. It is found that the predicted increase in the local field fluctuations as the Zn content in Ni1-xZnxFe2O4 decreases from x=0.9 down to 0.5 correlates with the observed increase in the broadening of the linewidth Γ A in the A-site sextets in the Mossbauer absorption spectrums accompanying the same changes in the zinc content.
COPPER TETRAMERS IN CaCuO2: AN EPR STUDY
Authors: IKRAM MOHD , SINGH R. J.
Published: July 2002

CaCuO2, one of the constituents of high-T c superconductors, has been studied by EPR. In deoxygenated phases, the study reveals the occurrence of isolated (CuO)4 units. More than one type (CuO)4 entities due to their association with disordered oxygen ions have been detected. The spin-Hamiltonian parameters for two types of (CuO)4 species have been reported.
RESONANCE PROPERTIES AND FREQUENCIES OF AN ELECTRO-RHEOLOGICAL CLUTCH AT HARMONIC LOAD
Authors: ORAVSKÝ VLADIMÍR
Published: July 2002

In this paper, a concentric electro-rheological clutch (ERC) is considered, embedded into a broader system: electro-hydro-aggregate (EHA) consisting of an induction motor as an electrodrive (ED) and a brake (B) as a loading machine. For ED, its dynamic moment characteristics and for B, a harmonic loading moment are taken into account. One starts from the corresponding nonlinear nondimensional dynamic model of EHA which is of the 5th order with 14 nondimensional parameters. The steady solution of the model can exhibit resonance which, due to complexity and extensiveness of the model, is very difficult to detect and analyze.

Therefore, an analytical solution in the frame of the first approximation is sought, based on the method of small parameter. For this, a few simplifying assumptions are adopted (undamped system, small amplitude and frequency of load and narrow gap in ERC). Then, undamped resonance frequencies are derived and analyzed. Results are compared with resonance curves of the original and unsimplified system and further solution of the problem in question is proposed.
ON RATIONAL PHASE-LOCKING OSCILLATIONS OF A SIMPLE SAWTOOTH OSCILLATOR WITH UJT
Authors: HASEGAWA YOSHITAKA , TANAKA RYUICHIRO , UEDA YOSHISUKE
Published: July 2002

There are some reports about sawtooth oscillations on various systems. The authors constructed the sawtooth oscillator circuit exploiting a Uni-Junction Transistor (UJT), and investigated various nonautonomous-like oscillations induced by an external sinusoidal input. Different from the cases of ordinary differential equation (ODE) systems driven with some periodic oscillation, this input periodically alternates only the threshold of the mode transition. Many systems in various fields of electrical circuits, biology and so on utilize threshold variation or modulation between operational modes, and our system is a very simple representative. Though our circuit behaves as a piecewise-continuous ODE system, we will suggest one-dimensional map depending on the phase of the external sinusoidal input. And we will study the background about the existence of various rational locking mode in the analytic method, numerical investigations and circuit experiments, identifying our system as a discrete dynamical system. This paper reveals not only the existing regions of the respective modes, but also reports about respective itineraries of periodic solutions geometrically. Readers will see that the mode distribution constitutes a Cantor set structure.
PLANE WAVES IN SYSTEMS HAVING AN INTRINSIC TIME LAG
Authors: INAMDAR SATISH R. , KARIMI I. A.
Published: July 2002

Time delays in many biochemical and ecological systems are intrinsic and can be approximately modeled as discrete. If diffusive forces are present in such systems and delayed inputs to the system also have an intrinsic space dependence, then we get a set of partial differential equations with a discrete lag. This paper presents a general, more improved and fairly complete analysis of plane waves in systems with intrinsic time lags. In this paper, we identify four types of critical points that can arise in such a system and consider simultaneous perturbations in a system parameter and the discrete time lag near such points. We develop two-parameter plane wave solutions using the reductive perturbation theory, discuss their stability and apply the results to an example predator–prey model. The presence of a time lag necessitates an iterative procedure for getting the desired solutions.
A NOVEL METHOD OF SOUND DATA DESCRIPTION BY MEANS OF CELLULAR AUTOMATA AND ITS APPLICATION TO DATA COMPRESSION
Authors: NARA SHIGETOSHI , ABE NAOYA , WADA MASATO , KUROIWA JOUSUKE
Published: July 2002

A novel method of binary data description using cellular automata is proposed. As an actual example, several trials are made to describe vocal and musical sound data digitized in a standard data format. The reproduced sounds are evaluated by "actual listening", by calculating "the signal to noise ratio" with respect to the original sound data, and by comparing "the Fourier power spectra" with those of the original sounds. The results show that this method is quite effective and provides a new means of data compression applicable in any field of digital data recording or transferring.
EDGE-TRANSITIVE GRAPH AUTOMORPHISMS AND PERIODIC SURFACE HOMEOMORPHISMS
Authors: LOS JÉRÔME E. , NITECKI ZBIGNIEW H.
Published: July 2002

An automorphism of a graph is edge-transitive if it acts transitively on the set of geometric edges (components of the complement of the vertices), or equivalently, if there is no nontrivial invariant subgraph. Every such automorphism can be embedded as the restriction to an invariant spine of some orientation-preserving periodic homeomorphism of a punctured surface. We find all the edge-transitive graph automorphisms and for each, find a complete list (up to a natural equivalence relation) of the possible ways that it can be embedded in a periodic homeomorphism.
STABILITY OF ORDER: AN EXAMPLE OF HORSESHOES "NEAR" A LINEAR MAP
Authors: BOLLT ERIK M.
Published: July 2002

We have been motivated by a question of "anticontrol" of chaos [Schiff et al., 1994], in which recent examples [Chen & Lai, 1997] of controlling nonchaotic maps to chaos have required large perturbations. Can this be done without such brute force? In this paper, we present an example in which a family of maps, Gε, numerically displays a transverse homoclinic point, and hence a horseshoe and chaos, for a fixed value of the parameter ε. We show that these maps converge pointwise to a linear map. Furthermore, a simple scaling conjugacy is shown for a family of maps which even shows geometric similarity of all relevant structures. This is in seeming contradiction to well-known structural stability results concerning horseshoes, but careful consideration reveals that these theorems require convergence in a uniform topology in function space. We show that no such convergence is possible for our family of maps, since it is impossible to find a finite radius disk which contains all of the horseshoes Λε for every ε. Thus, there is no contradiction. Our example may be considered to be a new kind of bifurcation route to chaos by horseshoes, in which rather than creating/destroying a horseshoe by creating/destroying transverse homoclinic points, the horseshoe is sent/brought to/from infinity.
TRANSLATING OODB METHOD TO RDB ROUTINE
Authors: FONG JOSEPH , CHEUNG SAN KUEN
Published: July 2002

A methodology is introduced for translating from methods in an object-oriented database to routines in a relational database. The approach consists of three steps. The first step is to translate method signature to Persistent Stored Modules signature. The second step is to translate method source language to (function/procedure) routine. The process includes Host Language, OSQL's Qualification, Query Translation, Update Transaction Translation, and Objects inside Object. The third step is to translate method invocation to routine invocation. According to this approach, object-oriented database methods can be translated to relational database routines that can be executed in the relational database environment assisted by a frame model and case statements listing all possible cases of binding conditions and actions. The significance of the finding is adding an open object-oriented interface on top of relational database system for database interoperability and in the development of an object-relational database management system.
SOFTWARE RESOURCE ARCHITECTURE
Authors: WOODSIDE C. M.
Published: July 2002

Performance is determined by a system's resources and its workload. Some of the resources are software resources which are an aspect of the software architecture; some of them are even created by the software behaviour. This paper describes software resources and resource architecture, and shows how resource architecture can be determined from software architecture and behaviour. The resource architecture is distinct from views of software architecture which describe software components, but it is related to the so-called "execution view" of architecture. The paper considers how resource architecture emerges during design, the relationship of software and hardware resources, some classes of resource architecture, and what they can tell us about system performance. Other uses of resource architecture are, to analyze deadlocks, to understand special software architectures developed for demanding situations, and to analyze how subsystems fit together when they share resources. Resource architecture can be described using description languages (ADLs) developed for software architecture.
ON SMALL CANCELLATION k-GENERATED GROUPS WITH (k-1)-GENERATED SUBGROUPS ALL FREE
Authors: BUMAGIN INNA
Published: July 2002

We give a set of effective sufficient conditions for a group G with small cancellation, generated by k elements, to have (k-1)-generated subgroups all free. We also prove that the group G has some more properties that in general do not hold in the whole class of the small cancellation groups.