bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved (1s)2 variational model for helium
Authors: Reed B. 
Published: August 2006

Abstract
The ground-state energy of neutral helium is estimated variationally with a trial wavefunction of the form ϕ≈e
−γ(rA/a
o)ne−γ(rB/a
o)n. This model represents a modification of traditional textbook examinations of this problem via inclusion of the power “n” as a second nonlinear variational parameter in addition to the usual effective nuclear charge γ and leads to an upper-limit on the ground state energy of −2.86107 Eh (Eh=1 hartree) in comparison with the traditional (n=1) result of −2.84766 Eh. This result represents a reduction of the percentage overestimate from the true ground-state energy (−2.90373 Eh) of from 1.93 to 1.47. In comparison with the maximum accuracy obtainable from an uncorrelated trial wavefunction, −2.86168 Eh, the present trial wavefunction reduces the percentage overestimate from 0.49 (n=1) to 0.021. The optimum values of (n, γ) are determined to be ≈(0.897, 1.825).
Characterization of electrical charge separation at the interface of two aqueous solutions in the presence of concentration gradients and cation/anion mobility ratio asymmetry
Authors: Cernescu Adrian , Luchian Tudor 
Published: August 2006

Abstract
Physical consequences of ionic diffusion processes play a major role on the outcome of electrophysiology experiments due to both their contribution to the ionic transmembrane transport and phenomena taking place at the measuring instruments interface. As most of the time heterogenities in biological media with respect to ionic diffusion constants are disregarded, we intended to look upon the general case of ionic diffusion at the interface of two liquids on which gradients of these diffusion constants no longer can be neglected. We developed a theoretical model for the diffusion potential which emerges at an aqueous interface under gradients of concentration and diffusion constants. The experimental validation of our model was achieved through potential difference measurements of the diffusion potential between two solutions containing sodium chloride (NaCl) and glycerine solutions of various concentrations. Within the studied domain of the electrical charge mobility ratio, we noticed that experimental results are in agreement with the theoretically inferred diffusion potential values. This demonstrates that the resulting relationship for the diffusion potential inferred from our model could be applied for other cases, as well. When the ionic solutions contains an indefinite quantity of glycerine or an unknown substance able to modify diffusion constants of sodium and chloride, it was shown that through measurements of the diffusion potential one can infer the unknown concentration of glycerine and the modified ionic mobility ratio. This, in turn, builds up the foundation for a novel yet simple and efficient analitycal sensing device for quantitative determination in the field.
Phase transitions in the adsorbed molecular chains
Authors: Lykah Victor , Syrkin Evgen 
Published: August 2006

Abstract
Rotational excitations of molecular adsorbed layers are studied theoretically. Nonlinear dynamical equations are obtained with accounting of quadrupolar interactions between molecules and freezing of translational degrees of freedom. The equilibrium positions of the molecules are found to be experimentally observed structures with alternating rotational ordering of planar rotors along the direction to the nearest neighbor (for linear or square structures) under low temperature. Dynamical analysis gives an integral of motion (energy) of the chain that in the long-wave limit leads consequently to the existence of four phases. The first one corresponds to oscillations near equilibrium ordered states. The second phase corresponds to low-energy rotational excitations along ‘valleys’ (easy directions in the effective potential) that do not destroy strong correlations between molecules while structural data can show rotational disorder (melting). The third phase corresponds to an energy that is enough to travel between ‘valleys’; only some ‘islands’ in the angle space are forbidden. Complete destruction of correlation when the energy is over the peaks of the effective potential corresponds to the fourth phase. Therefore rotational melting is a complex phenomenon that has several stages.
Superconducting states of the cylinder with a single vortex in magnetic field according to the Ginzburg-Landau theory
Authors: Zharkov Gely 
Published: August 2006

Abstract
Self-consistent solutions of the nonlinear Ginzburg-Landau (GL) equations are investigated numerically for a superconducting (SC) cylinder, placed in an axial magnetic field, with a single vortex on the axis (m=1). Two modes, which show the original state of the cylinder, SC or normal (s
0 andn
0), are studied. The field increase (FI) and the field decrease (FD) regimes are studied. The critical fields destroying the SC state withm=1 are found in both regimes. It is shown that in a cylinder of radiusR and GL-parameter ϰ, there exist a number of solutions depending only on the radial co-ordinater corresponding to different states such as M,e, d, p,i, n,
$$\bar n$$
,n
*, and the state diagram on the plane of the variables (ϰ,R) is described. The critical fields corresponding to intrastate transitions and the onset of hysteresis are obtained. The critical fieldH
0(R) dividing the paramagnetic and diamagnetic states of the cylinder withm=1 is determined. The limiting fields of supercooling or superheating of the normal state at which the restoration of the SC state occurs are established. It is shown, that (in both casesm=1,0) there exist two critical parameters,
$$\kappa _0 = {1 \mathord{\left/ {\vphantom {1 {\sqrt 2 = 0.707}}} \right. \kern-\nulldelimiterspace} {\sqrt 2 = 0.707}}$$
and
$$\kappa _0 = 0.93$$
, which divide bulk SC into three groups (with
$$\kappa< \kappa _0 ,\kappa _0 \leqslant \kappa \leqslant \kappa _c $$
and
$$\kappa > \kappa _c $$
), in accordance with the behavior in a magnetic field. The parameters
$$\kappa _0 $$
and
$$\kappa _c $$
mark the boundary for the existence of a supercooled normal
$$\bar n$$
-state in FD-regime and a superheated SC M-state in FI-regime respectively. It is shown, that the value
$$\kappa _* = 0.417$$
, which was claimed in a number of papers as related to type-I superconductors, is illusory.
Specific solutions of the generalized Korteweg-de Vries equation with possible physical applications
Authors: Bracken Paul 
Published: August 2006

Abstract
Solutions for a type of generalized Korteweg-de Vries equation which should have physical impact will be determined here. These types of solutions should have applications in the study of intrinsic localized modes optical waveguide arrays and fluid dynamics. It is shown that trigonometric and hyperbolic solutions can be obtained by matching powers and coefficients of the independent terms in the equation after the assumed solution has been substituted. As well, solutions to the equation in terms of more complicated Jacobe elliptic functions are determined.
Study of relaxation processes in monomolecular films by the step compression experiment
Authors: Vajda Ján , Weis Martin , Baranĉok Drahoslav , Cirák Július , Tomćík Pavol 
Published: August 2006

Abstract
Maxwell's displacement current flowing through a metal electrode/air gap/Langmuir monolayer was detected. MDC experimental results obtained during a step compression mode are presented and contrasted with the Debye-Brown rotational model. As an alternative approach a theoretical model based on an analogy with a nonideal gas of polar molecules is derived from Lagrange's equation of motion.
Pseudo-MV algebra of fractions and maximal pseudo-MV algebra of quotients
Authors: Piciu Dana 
Published: August 2006

Abstract
The aim of this paper is to define the notions of pseudo-MV algebra of fractions and maximal pseudo-MV algebra of quotients for a pseudo-MV algebra (taking as a guide-line the elegant construction of complete ring of quotients by partial morphisms introduced by G. Findlay and J. Lambek-see [14], p.36). For some informal explanations of the notion of fraction see [14], p. 37. In the last part of this paper the existence of the maximal pseudo-MV algebra of quotients for a pseudo-MV algebra (Theorem 4.5) is proven and I give explicit descriptions of this MV-algebra for some classes of pseudo MV-algebras.
Representation of finite groups and the first Betti number of branched coverings of a universal Borromean orbifold
Authors: Toda Masahito 
Published: August 2006

Abstract
The paper studies the first homology of finite regular branched coverings of a universal Borromean orbifold called B
4,4,4ℍ3. We investigate the irreducible components of the first homology as a representation space of the finite covering transformation group G. This gives information on the first betti number of finite coverings of general 3-manifolds by the universality of B
4,4,4. The main result of the paper is a criterion in terms of the irreducible character whether a given irreducible representation of G is an irreducible component of the first homology when G admits certain symmetries. As a special case of the motivating argument the criterion is applied to principal congruence subgroups of B
4,4,4. The group theoretic computation shows that most of the, possibly nonprincipal, congruence subgroups are of positive first Betti number.
Affinely equivalent complete flat manifolds
Authors: Sadowski Michal 
Published: August 2006

Abstract
Let E
Aff(Γ,G, m) be the set of affine equivalence classes of m-dimensional complete flat manifolds with a fixed fundamental group Γ and a fixed holonomy group G. Let n be the dimension of a closed flat manifold whose fundamental group is isomorphic to Γ. We describe E
Aff(Γ,G, m) in terms of equivalence classes of pairs (ε, ρ), consisting of epimorphisms of Γ onto G and representations of G in ℝm-n. As an application we give some estimates of card E
Aff(Γ,G, m).
Hyperpolarizability of 6-vertex carboranes quantum chemical study
Authors: Suponitsky Kyrill , Timofeeva Tatiana 
Published: August 2006

Abstract
Structure and molecular first hyperpolarizability (β) of nitro-amino-substituted 6-vertex 1,6-carboranes are investigated by means of DFT calculations. The results obtained have revealed that the relative orientation of substituents with respect to the carborane cage influences bond lengths distribution in the cage, which leads to significant changes in the values of hyperpolarizabilities. Calculations with different basis sets have demonstrated that the value of β is not significantly affected by the choice of basis set. The calculated data shows that hyperpolarizability of carborane molecules substituted for carbon atoms is lower than when substituted for boron atoms. For latter molecule, the value of β is of the same order as that of para-nitroaniline molecule.
Epicatechin-copper 9II) complexes: Damage of small intestinal epithelium
Authors: Stavrescu Ruxandra , Kimura Takahide , Hayakawa Fumiko , Ando Takashi 
Published: August 2006

Abstract
Four epicatechins [(−)-epicatechin (EC), (−)-epicatechin gallate (ECg), (−)-epigallocatechin (EGC), (−)-epigallocatechin gallate (EGCg)] and their corresponding copper complexes were compared with regard to their effect on the viability of Caco-2 colon cancer cells in vitro, measured by 3-(4,5-dimethylthyazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay. The viability of Caco-2 cells exposed to EC (1 mM), ECg (1 mM) or EGC (1mM) respectively, for 30 min, was comparable to that of the saline control group, while EGCg (1 mM) apparently enhanced cellular activity. in contrast, the cells treated with epicatechin-copper complexes were killed. Bivalent copper 91 mM), in similar conditions, did not affect the cells. No cell leakage or other histological differences were observed, implying a rapid cell death. The suggested mechanism of killing is by OH radical attack, produced in the presence of epicatechin-copper complexes, but not in the presence of either of the epicatechins or copper alone. The reaction sites are discussed.
1,3-bis(2,4,6-trinitrophenylaminooxy)propane and its 4-cyano-2,6-dinitrophenyl congener: Synthesis and properties
Authors: Covaci Irina , Ionita Petre , Caproiu Miron , Socoteanu Radu , Constantinescu Titus , Balaban Alexandru 
Published: August 2006

Abstract
Starting from N-hydroxyphthalimide (5) and 1,3-dibromopropane (6) we obtained 1,3-bis(phthalimidooxy)propane (7) which led to 1,3-bis(aminooxy)propane dihydrochloride (8). From its reaction with picryl chloride or 4-cyano-2,6-dinitrochlorobenzene, the two title compounds (4b, 4a) were obtained.
1H-NMR and 13C-NMR spectra are presented. For comparison with the analogous N-methoxy-2,6-dinitro-4-R-anilines 1a, 1b (R=CN or R=NO2), wer report the hydrophobic characteristics (by RPTLC), electronic spectra for the neutral compounds and their anions, pKa values, and the behavior towards oxidizers (DPPH, PbO2, Pb(CH3COO)4, KMnO4 and Ag2O); DPPH converts compounds 1a, 1b and 4a, 4b into betainic structures 2a, 2b respectively.
Synthesis of vinca alkaloids and related compounds 991. A new heterocyclic system
Authors: Csókási Pál , Gács-Baitz Eszter , Szántay Csaba 
Published: August 2006

Abstract
Utilising our earlier intermediate obtained by the umpolung reactivity of quinolizidine enamines, a new heterocyclic system: (11bSR, 15aSR)-1,2,3,6,11,14,15,15a-Octahydro-5H-indolo [2′,3′:3,4]pyrido[2,1-j]-1,6-naphthyridin-13(12H)-one was synthesised and its biological effects evaluated. Although modest, significant and selective effects were detected.
Determination of imazalil by on-line coupled capillary isotachophoresis with capillary zone electrophoresis
Authors: Kvasnička František , Dobiáš Jaroslav , Klaudisová-Chudáčková Kamila 
Published: August 2006

Abstract
A simple, rapid and reproducible capillary isotachophoretic on-line coupled with capillary zone electrophoresis (CITP-CZE) method for the determination of IMz in food packaging extracts and its residues in apples is described. A good separation of the IMZ from other sample constituents was achieved within 15 minutes without any sample clean up. Method characteristics (linearity, accuracy, intra-assay and detection limit) were determined. Less amount of time involved, sufficient sensitivity and low running cost are the important attributes of CITP-CZE method.
Ab initio and infrared spectral study of 4′-substituted phenylthiolbenzoates
Authors: Ivanova Bojidarka , Arnaudov Michail 
Published: August 2006

AbstractThe geometry of the 4′-cyano-(4′-CNPTB) and the 4′-methoxy-(4′-MePTB) phenylthiolbenzoates were obtained by ab initio calculations employing 6–31G basis set at Hartee-Fock level of theory. The results predict an extended form of the molecules and torsional angle between the phenyl rings at 90.85(6)0 and 90.87(3)0, respectively. On the basis of vibrational analysis the frequency assignment was carried out. The calculated frequencies were compared with the experimental IR spectral data in carbon tetrachloride, carbon disulfide solutions and in solid state.
A study of background emissions enhancements in nitrogen afterglows, due to addition of discharged O2, in connection with the reactions {N2 (A3Σu+, υ) + O(3P)}, {O2 (a1Δg) + N(4S)} and {O2 (a1Δg) + N2 (A3Σu+)}
Authors: Kamaratos Efstathios 
Published: August 2006

Abstract
Intensity enhancement due to the addition of discharged O2 is examined for background N2 (B Πg → A3Σu+) emissions in various flowing nitrogen afterglows. Possible implications are reported for the experimentally determined rate constants for the reactions {N2 (A3Σu+, υ) + O(3P)}, and {O2 (a1Δg) + N(4S)}, as a result of the present study. The present, as well as previously reported, N2 (B Πg → A3Σu+) emissions intensity enhancements suggest complementary conclusions. Previous differences in experimental results reported for the {O2 (a1Δg) + N(4S)} reaction [based on studies observing the decay of either O2 (a1Δg) molecules or N(4S) atoms alone] are reconciled by a unifying additional interpretation. This interpretation leads to a rate constant estimate for the energy transfer reaction, {O2 (a1Δg) + N(2(A3Σu+)}, deduced to account for the above N2 (B3Πg → A3Σu+) emissions intensity enhancements.
Mechanistic investigations of oxidation of isatins by sodium N-chlorobenzenesulfonamide in alkaline medium: A kinetic study
Authors: Puttaswamy  , Jagadeesh R. 
Published: August 2006

Abstract
Oxidation of isatins (isatin, 5-methylisatin, 5-bromoisatin and 5-nitroisatin) to their anthranilic acids was performed efficiently with sodium N-chlorobenzenesulfonamide or chloramine-B (CAB) in alkaline medium at 35±0.1°C. The reactions follow identical kinetics for all the isatins, being first-order dependence each in [CAB]o and [Isatin]o and inverse fractional-order on [NaOH]. Addition of halide ions and benzenesulfonamide, reduction product of CAB, do not significantly affect the rate. Variation of ionic strength of the medium had no effect on the rate, while the dielectric effect is negative. The solvent isotope effect was studied using D2O. Activation parameters for the overall reaction have been computed. The rates satisfactorily correlate with the Hammett σ relationship and the reaction constant ρ is −0.31 signifies that electron releasing groups accelerate the reaction while the electron withdrawing groups retard the rate. Values of ΔH≠ and ΔS≠ are linearly related and an isokinetic relationship is observed with β=376 K, indicating the reaction is controlled by enthalpy. The stoichiometry of the title reaction is found to be 1∶1. Oxidation products of isatins were identified as their corresponding anthranilic acids and the yields were found to be around 90 %. The observed results have been explained by a plausible mechanism and the related rate law deduced. This method offers several advantages including high yield of the products, short reaction times, easier isolation of products, and stable, cost effective and relatively non-toxic reagents, which make the reaction process simple and smooth.
Determination of p-nitrobenzene-azo-naphthol by an oscillating chemical reaction using the analyte pulse perturbation technique
Authors: Gao Jinzhang , Sun Kanjun , Yang Wu , Zhou Huixian 
Published: August 2006

Abstract
A simple analytical method for the determination of p-nitrobenzene-azo-naphthol was proposed by a sequential perturbation with different amounts of p-nitrobenzene-azo-naphthol on an oscillating chemical system. The method involves a Cu(II)-catalysed oscillating reaction between hydrogen peroxide and sodium thiocyanate in alkaline medium with the aid of continuous-flow stirred tank reactor (CSTR). A good linear relationship between the changes, oscillation amplitude or/and period, and the concentration of p-nitrobenzene-azo-naphthol was obtained. The use of analyte pulse perturbation technique provides a possibility of sequential determination in a same oscillating system, due to a new steady state that reappeared rapidly after each perturbation. The calibration curve fits a linear equation very well when the concentration of p-nitrobenzene-azo-naphthol ranging from 5.2×10−7 to 3.3×10−3M. Influence of temperature, injection point, flow rate and reactants variables on this system were investigated in detail.
Synthesis, spectral characterization, redox and antimicrobial activity of Schiff base transition metal(II) complexes derived from 4-aminoantipyrine and 3-salicylideneacetylacetone
Authors: Raman Natarajan , Thangaraja Chinnathangavel , Johnsonraja Samuelraj 
Published: August 2006

Abstract
A novel tetradentate N2O2 type Schiff base, synthesized from 1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one(4-aminoantipyrine) and 3-salicylidene-acetylacetone, forms stable complexes with transition metal ions such as CuII, NiII, CoII and ZnII in ethanol. Microanalytical data, magnetic susceptibility, IR, UV-Vis.,1H-NMR, ESR and Mass spectral techniques were used to confirm the structures. Electronic absorption spectra of the complexes suggest a square-planar geometry around the central metal ion. These complexes show higher conductance values, supporting their electrolytic nature. The monomeric nature of the complexes was confirmed from their magnetic susceptibility values. Cyclic voltammogram of the copper(II) and nickel(II) complexes in DMSO solution at 300 K were recorded and the results are discussed. The X-band ESR spectra of the copper complex were recorded and the molecular orbital coefficient values were calculated from the spectra. The in vitro antimicrobial activities of the investigated compounds were tested against bacteria such as Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis and Escherichia coli and fungi like Aspergillus niger and Rhizoctonia bataicola. Most of the metal chelates show higher antimicrobial activity for the above microorganisms than that of the free ligand.
Bioaccumulation study of acrylates in algae (Chlorella kessleri) by Py-GC and Py-GC/MS
Authors: Halás Ladislav , Oriňák Andrej , Sharif Abubaker , Ádámová Monika , Ladomerský Juraj 
Published: August 2006

Abstract
Acrylate monomers methylmethacrylate (MMA) and cyclohexylmethacrylate (CHMA) bioaccumulation has been determined in aquatic organism, algae (Chlorella kessleri). Algae were collected in amount of 0.4 mg and directly injected to the pyrolytical cell. In algae bodies accumulated monomers were analysed by pyrolysis gas chromatography (Py-GC) and pyrolysis gas chromatography coupled with mass spectrometry (Py-GC/MS). Traces of the accumulated monomers in algae body can be determined after 1-, 2-, 3-weeks of incubation. Maximum content of MMA was determined after 3-week of experiment, contrariwise in the case of CHMA after 2-week exposition. Relationship with pyrolysis temperature has also been studied.
Redundant wavelet processing on the half‐axis with applications to signal denoising with small delays: theory and experiments
Authors: Chaplais François , Tsiotras Panagiotis , Jung Dongwon 
Published: August 2006

AbstractA wavelet transform on the negative half real axis is developed using an average‐interpolation scheme. This transform is redundant and can be used to perform causal wavelet processing, such as on‐line signal denoising, without delay. Nonetheless, in practice some boundary effects occur and thus a small amount of delay is required to reduce them. The effect of this delay is studied using a numerical example of a signal with large noise and sharp transients. It is shown that the delay required to obtain acceptable denoising levels is decreased by using the proposed redundant transform instead of a non‐redundant one. We also present results from the experimental implementation of the proposed algorithm for the denoising of a feedback signal during the control of a three‐phase permanent‐magnet synchronous brushless DC motor. Copyright © 2006 John Wiley & Sons, Ltd.
How do simple programs behave
Authors: Wolfram Stephen 
Published: August 2006

AbstractWhereas once the world view of the ancient world was shifted by Pythagorean mathematics, scientific knowledge and human perception has been contested in the 21st century by developments in computation. In his ground‐breaking book Stephen Wolfram, the British physicist and creator of the Mathematica program, asserted that the complexity of the universe could be clearly understood in terms of simple programs. Here in an exclusive extract, Wolfram describes how one of the most straightforward programs, cellular automata, despite adhering to simple rules, yields some surprisingly complex results. Copyright © 2006 John Wiley & Sons, Ltd.
Metaphysics of genetic architecture and computation
Authors: Chu Karl 
Published: August 2006

AbstractKarl Chu ruminates on the far‐reaching impact that the convergence of computation and biogenetics will have on the unfolding history of man and nature. Could the world be ‘moving into the so‐called Post‐Human Era, which will bring forth a new kind of biomachinic mutation of organic and inorganic substances’? How can architects reconfigure the practice of their discipline in order to meet the demands of this computational and biogenetic revolution? Copyright © 2006 John Wiley & Sons, Ltd.