bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the extraction equilibrium of ion-association complexes of molybdenum (VI) with some polyphenols and thiazolyl blue. extraction-spectrophotometric determination of molybdenum
Authors: Dimitrov Atanas , Lekova Vania , Gavazov Kiril , Boyanov Boyan 
Published: August 2006

Abstract
The extraction process of ternary ion-association complexes of molybdenum (VI) with some polyphenols (4-nitrocatechol, 2,3-dihydroxy naphthalene) and thiazolyl blue has been investigated by using an extraction-spectrophotometric method. The optimum conditions for their quantitative preparation in aqueous medium and subsequent extraction into an organic solvent have been found. The extraction, distribution and association constants, and the recovery factors have been calculated. The composition of the complexes has been determined. A precise, sensitive and simple extraction-spectrophotometric method for determination of molybdenum in products from ferrous metallurgy has been developed.
Preparation of a set of selectively protected disaccharides for modular synthesis of heparan sulfate fragments: toward the synthesis of several O-sulfonated [β-D-GlcUA-(1→4)-β-D-GlcNAc]OPr types
Authors: Hassan Hammed 
Published: August 2006

Abstract
A concise method for a stereocontrolled synthesis of a set of selectively protected disaccharides is reported. Coupling of the donor 11 onto acceptors 23 and 24, promoted by trimethylsilyl triflate-N-iodosuccinimide (TMSOTf-NIS), generated the disaccharides 25 and 26. Under typical conditions, condensation of the fully protected donor 12 onto acceptors 23 and 24 produced the disaccharides 27 and 28. The building blocks 25–28 were prepared in moderate yields having exclusive β-stereoselectivity. A unique pattern of protecting groups distinguished clearly between positions to be sulfated and functional groups remaining as free hydroxyl groups. Acetyl and/or levulinoyl esters temporarily protected the positions to be sulfated, while benzyl ethers were used for permanent protection. The anomeric positions were protected as allyl ethers, whereas the 4′-positions were masked as p-methoxybenzyl (PMB) ethers. The orthogonality of the PMB and allyl groups can then be used for further elongation of the chain by recurrent deprotection and activation steps. The hydroxyl group, OH-6, of glucosamine moieties was protected as a TBDPS ether to avoid oxidation. A five-step deprotection/sulfonation sequence was applied to the disaccharide 27 to generate the corresponding sulfated [β-D-GlcUA-2-OSO3Na-(1→4)-β-D-Glc pNAc]-(1→O-Pro) 34.
The effect of flame coal oxidation on the solid and soluble products of its extraction
Authors: Pietrzak Robert , Wachowska Helena , Nowicki Piotr 
Published: August 2006

Abstract
Solid and soluble products of THF and CH2Cl2 extraction of flame coal oxidised by four different oxidising agents (peroxyacetic acid (PAA), 5% HNO3, O2/Na2CO3, air/125 °C) were studied by elemental analysis and FTIR. The extraction yield with THF was much higher than that with CH2Cl2 for all samples. The greatest changes in elemental composition were in the extracts from coal oxidised by nitric acid. The sulphur content was lowest in extracts from coal oxidised with 5% HNO3 and PAA. FTIR confirmed that coal treatment with nitric acid incorporates nitrogen into the coal structure.
Nonadaptive search problem with sets of equal sum
Authors: Kolev Emil 
Published: August 2006

Abstract
Consider the set A={1,2,3,…,2n}, n≥3 and let x∈ A be unknown element. For given natural number S we are allowed to ask whether x belongs to a subset B of A such that the sum of the elements of B equals S. We investigate for which S it is possible to find x using a nonadaptive search.
Smooth approximations without critical points
Authors: Hájek Petr , Johanis Michal 
Published: August 2006

Abstract
In any separable Banach space containing c
0 which admits a C
k-smooth bump, every continuous function can be approximated by a C
k-smooth function whose range of derivative is of the first category. Moreover, the approximation can be constructed in such a way that its derivative avoids a prescribed countable set (in particular the approximation can have no critical points). On the other hand, in a Banach space with the RNP, the range of the derivative of every smooth bounded bump contains a set residual in some neighbourhood of zero.
Decompositions of the category of noncommutative sets and Hochschild and cyclic homology
Authors: Słomińska Jolanta 
Published: August 2006

Abstract
In this note we show that the main results of the paper [PR] can be obtained as consequences of more general results concerning categories whose morphisms can be uniquely presented as compositions of morphisms of their two subcategories with the same objects. First we will prove these general results and then we will apply it to the case of finite noncommutative sets.
A pathwise solution for nonlinear parabolic equations with stochastic perturbations
Authors: Iftimie Bogdan , Varsan Constantin 
Published: August 2006

Abstract
We analyse here a semilinear stochastic partial differential equation of parabolic type where the diffusion vector fields are depending on both the unknown function and its gradient ∂
xu with respect to the state variable, ∈ ℝn. A local solution is constructed by reducing the original equation to a nonlinear parabolic one without stochastic perturbations and it is based on a finite dimensional Lie algebra generated by the given diffusion vector fields.
The prime and maximal spectra and the reticulation of BL-algebras
Authors: Leuštean Laurenťiu 
Published: August 2006

Abstract
In this paper we study the prime and maximal spectra of a BL-algebra, proving that the prime spectrum is a compact T
0 topological space and that the maximal spectrum is a compact Hausdorff topological space. We also define and study the reticulation of a BL-algebra.
Combined polymerization catalysis of nickel complex and zirconocene for branched polyethylene
Authors: Cui Yong , Shao Changxing , Sun Wen-Hua 
Published: August 2006

AbstractThe polymerization behavior of 2-(2′-pyridyl) quinoxaline nickel dibromide/Cp2ZrCl2/MAO system was investigated in three ways: the Ni catalyst was added first, followed by addition of Zr catalyst (method I); the Ni and Zr catalysts were added simultaneously (method II); and the Zr catalyst was added first, followed by addition of Ni catalyst (method III). Results of GC-MS, GPC,13C NMR and DSC investigations indicated that the properties of resulting polyethylene were greatly varied by changing feeding orders of the two catalysts. Decreasing Ni/Zr molar ratio or increasing polymerization temperature gave corresponding polyethylenes with less branches and higher melting point. Compared to the procedure using Cp2ZrCl2 catalyst only, the activity of Zr catalyst in those combined system decreased because of the competition of ethylene between the [Ni−C] and [Zr−C] active centers. In addition, other zirconocenes were also employed as copolymerization catalysts in the combined system with nickel complex. compared to Cp2ZrCl2 case, the ethyl-bridged Zr catalyst performed better for polymerization of ethylene while the Si-bridged Zr catalyst showed better copolymerization ability.
Thermal and kinetic characteristics in non-isothermal conditions of some aromatic copolyethers containing an octomethylenic spacer
Authors: Prajinaru Mihaela , Hurduc Natalia , Alazaroaie Silvia , Catanescu Otilia , Hurduc Nicolae 
Published: August 2006

AbstractThe paper presents a study of the thermal properties of some aromatic polyethers obtained by phase trasfer catalysis technique. The polymes were synthesized starting from 1,8-dichloro-octane and various bisphenols: 4,4′-dihydroxyazobenzene, 4,4′-dihydroxydiphenyl, bisphenol A and 2,7-dihydroxynaphthalene. Molecular simulations were performed in order to obtain supplementary information concerning the chain conformation and inter-chain interactions. The presence of azobenzenic moieties induces high phase transition values, situated near the thermal stability limit. Therefore, the thermogravimetrical study of these polymers is very important for establishing the temperature limits for DSC and optical microscopy studies. All the polymers present a good thermal stability situated above the isotropization values. In these circumstances no special precautions are necessary for the characterization methods of the liquid crystalline behavior. The kinetic characteristics suggest a similar degradation mechanism by successive reactions. The inter-chain interactions do not influence the thermostability of the samples if the polar surface of the polymer is situated below a certain value.
Methods for the calculation of occupied volumes in glassy polymers: The lattice integration and the monte carlo methods
Authors: Rozhkov E. , Schukin B. , Ronova I. 
Published: August 2006

AbstractA new model for characterizing the free volume of a glassy polymer—gas systems is proposed. An improved method for the calculation of occupied volume per monomer unit was developed within the limits of this model. The model assumptions, error estimates and algorithm efficiencies are described. Using the example of polyvinyltrimethylsilane, it is shown that linear dependences of logarithms of the diffusion and the permeability coefficients on specific accessible volume for inert gases exist.
Thermally induced oxidative trimerization of benzimidazole by copper(II) chloride in the solid state
Authors: Bhattacharya Rahul , Ray Sibdas , Ray Jayanta , Ghosh Ashutosh 
Published: August 2006

AbstractBenzimidazolium trichlorocuprate(II) undergoes a redox reaction in the solid state at elevated temperature (∼240°C) to produce the cyclic trimer of benzimidazole and cuprous chloride. The trimer has been characterized by IR, NMR, and Mass spectroscopy. It has also been synthesized in lower yield by heating the mixtures of CuCl2 and benzimidazole in different ratios or heating other compounds of CuCl2 and benzimidazole. The absorption, emission, and excitation spectra of the trimer in two different solvents (TFA and DMSO) and a comparison of these results with those of benzimidazole are presented here.
Hydrazyl, Nitronyl-, and imino-nitroxides: Synthesis, properties and reaction with nitric oxide and nitrogen dioxide
Authors: Constantinescu Titus , Ionita Petre , Chiorescu Ion , Ionita Gabriela 
Published: August 2006

AbstractTen novel and stable free radicals of nitronyl-, imino-nitroxide and hydrazyl type compounds were synthesized and their physico-chemical properties investigated. UV-Vis and ESR spectroscopic data, as well as the lipophilicities and specific hydrophobic areas of the compounds are compiled. The reaction of these radical compounds with nitric oxide and nitrogen dioxide was also investigated. The radicals synthesized, show selectivity in their reaction with these nitric oxides, depending on their structure (nitronyl-nitroxide radicals react with NO, while hydrazyl radicals react with NO2). The processes are easily monitored by UV-Vis or ESR spectroscopy.
Synthesis and crystal structure of 1-ethyl-3-(phenyl)-1,2,3-triazolium percholorate
Authors: Doreswamy Beeranahally , Mahendra Madegowda , Anandalwar Sridhar , Prasad Javaregowda , Mantelingu Kempegowda ,   Basappa, Rangappa Kanchugarakoppal 
Published: August 2006

AbstractThe isolation of stable carbenes of the Arduengo (1a) and Wanzlick (2a) type has prompted us to look for stable nitrenium ions of the related structural type 1-ethyl-3-(phenyl)-1,2,3-triazolium perchlorate (6+). The title compound C10H14Cl N3O4 was isolated and structure was investigated by X-ray crystallography. It crystallizes in the monoclinic space group P21/c with cell parameters a=6.697(4) Å, b=9.724(9) Å, c=19.844(2) Å and Z=4. The final residual factor is R1=0.0471 for 1545 reflections with I>2σ(I). The structure exhibits intermolecular hydrogen bonds.
Transverse electron focusing as a way of studying phonon kinetics. Turbulence of phonon flow
Authors: Tsoi Valerii 
Published: August 2006

AbstractNovel techniques have been created for studying phonon kinetics. A supersonic conduction electron flux is used to produce a phonon flux. Transverse electron focusing (TEF) is applied for checking the electron gas affected by phonons. A turbulent regime of phonon flow-phonon flux step broadening-reveals itself as step broadening of non-equilibrium electron flux.
Influence of the sample orientation in Sn2P2S6 crystals on the hydrostatic piezoelectric coefficients
Authors: Panoŝ Stanislav , Panoŝová Dagmar 
Published: August 2006

AbstractThe influence of the sample orientation on the effective value of the hydrostatic piezoelectric coefficients dh(i) of Sn2P2S6 crystals has been studied. The hydrostatic piezoelectric coefficients dh(1) and d′h(3), were measured, dh(1)=(244±3) pC/N and d′h(3)=(92±1) pC/N. The hydrostatic piezoelectric coefficient d h(3) for orthogonal axis system was calculated to be dh(3)=(87±2) pC/N. The, optimal orientation of the sample has been found as (Xy l)−20°-cut. Maximal value of the effective hydrostatic piezoelectric coefficient d h(1) equals 260 pC/N. Double rotated samples were also studied. The orientation of the samples insensitive to the pressure has been found. The theoretical mean value of hydrostatic piezoelectric coefficient (d h)mean corresponding to randomly oriented Sn2P2S6 grains in a poled composite has been calculated to be (d h)mean=136 pC/N.
The scattering of light on sound waves in the hypersonic range of frequencies the directional sensitivity of Brillouin light scattering
Authors: Błachowicz Tomasz 
Published: August 2006

AbstractBrillouin spectroscopy of acoustic phonons in transparent crystals and nontransparent metallic Co/Cu superlattices is reviewed. The method presents a directional sensitivity of the experiment. This feature is useful in elastic constants measurements in crystals and analysis of in-plane anisotropies of hyper-sound and spin waves in superlattices. Results for the LiTaO3, LiNbO3, LiNbO3:Cu, SLGO, SLAO crystals are provided. Spin wave results for the Co/Cu superlattices are presented.
Simple analytic solution of fireball hydrodynamics
Authors: Csörgő Tamás 
Published: August 2006

AbstractA new family of simple analytic solutions of hydrodynamics is found for slowly expanding, rotationally symmetric fireballs assuming an ideal gas equation of state. The temperature profile is position-independent only in the collisionless gas limit. The Zimányi-Bondorf-Garpman solution and the Buda-Lund parameterization of expanding hydrodynamic particle sources are recovered as special cases. The results are applied to predict new features of proton correlations and spectra for 1.93 AGeV Ni+Ni collisions.
Runaway of electrons in dense gases and mechanism of generation of high-power subnanosecond beams
Authors: Tkachev Alexey , Yakovlenko Sergei 
Published: August 2006

AbstractNew understanding of mechanism of the runaway electrons beam generation in gases is presented. It is shown that the Townsend mechanism of the avalanche electron multiplication is valid even for the strong electric fields when the electron ionization friction on gas may be neglected. A non-local criterion for a runaway electron generation is proposed. This criterion results in the universal two-valued dependence of critical voltage U cr on pd for a certain gas (p is a pressure, d is an interelectrode distance). This dependence subdivides a plane (U cr, pd) onto the area of the efficient electron multiplication and the area where the electrons leave the gas gap without multiplication. On the basis of this dependence analogs of Paschen’s curves are constructed, which contain an additional new upper branch. This brunch demarcates the area of discharge and the area of e-beam.The mechanism of the formation of the recently created atomospheric pressure subnanosecond e-beams is discussed. It is shown that the beam of the runaway electrons is formed at an instant when the plasma of the discharge gap approaches to the runaway electrons is formed at an instant when the plasma of the discharge gap approaches to the anode. In this case a basic pulse of the electron beam is formed according to the non-local criterion of the runaway electrons generation.The role of the discharge gap preionization by the fast electrons, emitted from the plasma non-uniformities on the cathode, as well as a propagation of an electron multiplication wave from cathode to anode in a dense gas are considered.
Multiscale semicontinuous thin film descriptors
Authors: Boldyš Jiří , Hrach Rudolf 
Published: August 2006

AbstractIn experimental thin film physics, there is a demand to characterize a growing thin film or the thin film resulting from an experiment. While methods for discontinuous, island-like thin films have been developed, there is a lack of results directly applicable to semicontinuous thin film description. In this contribution, a unique combination of image processing methods is collected and further developed, which results in a novel set of semicontinuous thin film descriptors. In particular, the shape of the thin film contours and the thin film image intensity profiles are analyzed in a multiscale manner. The descriptiveness of the proposed features is demonstrated on a few thin film photographs from real experiments. This work establishes a basis for further measurement, description, simulation or other processing in the physics of semicontinuous thin films, using any direct imaging modality.
Hyperfine structure operator in the tensorial form of second quantization
Authors: Gaigalas Gediminas , Rudzikas Zenonas , Scharf Oliver 
Published: August 2006

AbstractThe general tensorial form of the hyperfine interaction operator in the formalism of second quantization is presented. Both diagonal and off-diagnonal matrix elements of the above-mentioned operator are found using an approach based on a combination of second quantization in the coupled tensorial form, angular momentum theory in three spaces (orbital, spin and quasispin) and a generalised graphical technique. This methodology allows us to account for correlation effects efficiently and, therefore, to study the hyperfine interactions in complex many-electron atoms, those with openf-shells included, in a practical manner. All this will lead us to design an efficient program for large scale calculations of hyperfine structure and isotope shift.
Studies of the soluble part of oxidised coals
Authors: Pietrzak Robert , Kozłowski Mieczysław , Wachowska Helena , Yperman Jan 
Published: August 2006

Abstract
Soluble products obtained from the oxidation of four types of coal, each characterised by different degree of coalification and different degree of sulphur content, are studied. The coals are oxidised with peracetic acid (PAA) and nitric acid. Analyses are performed by Atmospheric Pressure-Temperature Programmed Reduction (AP-TPR) and Fourier Transform Infrared Spectroscopy (FTIR). The soluble products contain much more sulphur than the insoluble products of oxidation. The products obtained from the reaction with HNO3 contain higher amounts of inorganic sulphur compounds, while those obtained from the reaction with PAA are characterised by an increased content of organic sulphur species.
Photo- and thermoinduced ring opening reaction of 2[(1,3,3-trimethylindoline-2(1H)-yliden)propen-1-yl]-3,3-dimethylindolino[1,2-b]-oxazolidine in polymer films
Authors: Petkov I. , Charra F. , Nunzi J , Deligeorgiev T. 
Published: August 2006

Abstract
The influence of UV light and temperature on poly(methylmethacrylate) (PMMA) and poly(vinylchloride) (PVC) films, doped with 2[(1,3,3-trimethylindoline-2(1H)-yliden)propen-1-yl]-3,3-dimethylindolino[1,2-b]-oxazolidine has been investigated. The radiation-induced colour was analyzed spectrophotometrically at the maximum of the absorption peak at 560 nm. The effect of the temperature on unirradiated and irradiated films was studied. The results demonstrate a strong photochromic and a weak thermochromic behaviour of the PMMA and PVC films. The relationship of photocolouration-thermal decolouration is discussed based on the spectral results reported here.
Determination of selenium in infant foods using electrothermal atomic absorption spectrometry with direct slurry sample introduction
Authors: Baralkiewicz Danuta , El-Sayed Usama , Filipiak Marian , Gramowska Hanka , Mleczek Miroslaw 
Published: August 2006

Abstract
Slurry sampling electrothermal atomic absorption (SS ETAAS) was applied to the development of a sensitive and precise method for selenium determination in infant foods without sample pretreatment. Suspensions prepared in a medium containing 0.1% Triton X-100, 0.5 or 5% v/v concentrated HNO3 were directly introduced into the furnace. The accuracy of the procedure was confirmed by analysis of a standard reference material and comparison with hydride generation atomic absorption spectrometric (HGAAS) procedure. The characteristic mass is 44 pg and detection limit 0.43 μg·l−1.
Intermicellar material exchange in reverse micelles formed by ionic AOT and nonionic Igepal surfactants studied by means of pulse radiolysis. Influence of the temperature
Authors: Gębicki Jerzy 
Published: August 2006

Abstract
The recombination of thiocyanate anion radicals, (SCN)2−, formed pulse radiolytically within the water pools of reverse micelles stabilized with anionic AOT and nonionic Igepal surfactants, was proved as an indicator reaction to study intermicellar exchange. It was found that the exchange process is slower inIgepal than in AOT reverse micelles with the same water to surfactant ratio. The apparent activation enthalpy and entropy of the exchange process were determined in different alkanes. For the AOT and Igepal reverse micelles the activation parameters increase with the droplet size, but for the AOT systems they do not significantly change with the increase of droplet concentration. For non-percolated systems the activation parameters for Igepal reverse micelles approach those for AOT reverse micelles. This result supports existing suggestions that the mechanism of intermicellar exchange does not differ in principle between reverse micelles stabilized with ionic and nonionic surfactants.
Comparative study of structural stability in [NH4−n
(CH3)n]2HgCl4 and in related compounds
Authors: Amami M. , Salah A. 
Published: August 2006

Abstract
The structural instability of the [NH4−n
(CH3)n]2HgCl4 group has been investigated. Consideration of different crystals of this family shows that the H-bonds, obviously, hinder the appearance of incommensurate modulation. The dependence of phase transition sequence on the sizes of cation and anion may be obtained only for crystals with simple cation. The appearance of H-bonds complicates the situation and, leads to gradual disappearance of IC phase in the A2BX4 family.
Analysis of numerical limits in 2-D simulations of a ferromagnetic/antiferromagnetic interface using the random field Ising model
Authors: Błachowicz Tomasz 
Published: August 2006

Abstract
This paper explains the Random Field Ising Model simulations of a two-dimensional ferromagnetic/antiferromagnetic interface, influenced by the exchange-bias interaction. Exchange-biased shifts, coercivity fields, the number of unreversed spins as well as the numerical errors are provided. These were tested for different structure dimensions and boundary conditions in order to find limitations of the method. The algorithm developed is simple, very effective, and provides deeper insight into the nature of the exchange-bias phenomenon.
Theoretical calculations of the temperature dependence of the electrical and thermal conductivities of liquid gallium
Authors: El-Daher M. , Murphy Richard 
Published: August 2006

Abstract
The electrical and thermal resistivities of liquid gallium are calculated over a range of temperatures above the melting point using the solutions of the Boltzmann equation. The experimental x-ray structure factor of Waseda and the form factor derived using the Heine-Abarenkov model potential are used in these calculations. The ratio of the electrical and thermal conductivities is calculated and compared to experimental values and to the theoretical Lorenz number.