bluuebunny/crossref_metadata_2025_split huggingface dataset:
Propagation of Ultra-High Energy Cosmic Rays in Extragalactic Magnetic Fields
Authors: Wibig Tadeusz 
Published: August 2006

AbstractIn this paper we will discuss the problem of Ultra High Energy Cosmic Rays (UHECR) and show that the idea of a Single Source Model established by Erlykin and Wolfendale (1997) to explain the features seen in cosmic ray energy spectra around the 1015 eV region can be successfully applied also for the much higher energies. The propagation of UHECR (of energies higher than 1019 eV) in extragalactic magnetic fields can no longer be described as a random walk (diffusion) process and the transition to rectilinear propagation gives a possible explanation for the so-called Greisen-Zatzepin-Kuzmin (GZK) cut-off which still remains an open question after almost 40 years. A transient “single source” located at a particular distance and producing UHECR for a finite time is the proposed solution.
Multi-mode ground state interaction terms in C60-based electron donor-acceptor complexes
Authors: Sheka Elena 
Published: August 2006

AbstractQuantum-chemical testing of donor-acceptor properties of binary molecular complexes, related to the singlet state, is suggested as QCh calculations of studied systems and their constituents by using both spin-nondependent (RHF) and spindependent (UHF) versions of the exploited computational tool. The avoided crossing of intermolecular interaction terms of neutral moleculesE int(A 0 B 0) and molecular ionsE int(A + B −) causes a multi-mode character of the ground state term. The dependence of D-A complex properties on the type of the term, space positions of the term minimum, and the interrelation of the corresponding energies are discussed. The suggested approach has been applied to binary complexes C60+X (X=TAE, TDAE, DMMA, COANP, 2Li, Mg).
Polarons in axial transport in single-layer high-Tc superconductors
Authors: Andreev Alexander , Tsintsarska Stefka , Dimitrova-Ivanovich Maria , Polyanski Ivaylo , Georgiev Mladen , Gochev Alexander 
Published: August 2006

AbstractThe temperatureT dependencies ρ(T) of normal state electric resistivitiesρ c (axial) andρ ab (in plane) of single-layer high-T c superconductors show common trends: AsT is raised, the resistivity first drops steeply before it starts rising αT above an apparent semiconductor-to-metal crossoverT cross. To analyze ρ(T) we plottT/ρ againstT at various dopingsx for bothρ c andρ ab.T/ρ is inversely proportional to the traversal time across a potential barrier as an ionic particle drifts in an electric field. We findT/ρ in good agreement with theT dependence of the quantum rate of migrating particles: AsT is raised, a zero-point rate at the lowestT is extended to a nearly flat plateau before a thermally activated branch sets in. We also find evidence for the admixture of 1- & 2-phonon absorptions below the Arrhenius range. These features shape the semiconductor-like branch below Tcross. AboveT cross a metallic-like branch sets in, its αT character deriving from the field coupling of the migrating particle. Our analysis suggests that metal physics may not suffice if ionic features play a role in transport. We attribute our conclusions to the drift of strong-coupling polarons along Cu−O bonds. These “bond polarons” originate from carrier scattering by double-well potentials associated with the bonds. A bond polaron dissociates to a free hole as it passes onto a neighboring O-O link.
Electrical properties and memory effect in the field effect transistor based on organic ferroelectric insulator and pentacene
Authors: Matsuo Yasumitsu , Ijichi Takehiko , Yamada Hironori , Hatori Junko , Ikehata Seiichiro 
Published: August 2006

AbstractWe have fabricated a field effect transistor (FET) based on an organic ferroelectric insulator and molecular conductor, and investigated the electrical properties and memory effects on the PEN-FET. We have observed a drastic change in the drain current at around the coercive electric fieldE c of the organic ferroelectric insulator in not only a FET (PEN-FET) based on a pentacene (PEN) film but also a FET (IPEN-FET) based on an iodine doped PEN film. The magnitude of the change of the drain current for the IPEN-FET is 200 times larger than that for the PEN-FET. It is expected from these results that the PEN-FET (especially the IPEN-FET) is an improvement in such devices, since it operates at a low gate electric field accompanied by the appearance of the spontaneous polarization in the organic ferroelectric insulator. In addition, we have found that the drain current for the PEN-FET does not return to the initial drain current ofE G=0 V/cm for more than one week, even if the gate electric field is changed to 0 V/cm from 500 V/cm(>E c). From these results, it is suggested that the PEN-FET becomes a memory device.
Mean-field expansion and meson effects in chiral condensate of analytically regularized Nambu-Jona-Lasinio model
Authors: Jafarov Rauf , Rochev Vladimir 
Published: August 2006

AbstractScalar meson contributions in chiral quark condensate are calculated in the analytically regularized Nambu-Jona-Lasinio model using the framework of mean-field expansion in bilocal-source formalism. The sigma-meson contribution for physical values of the parameters is found to be small. Pion contribution is found to be significant and should be taken into account for the choice of the parameter values.
The ring opening and oligomerisation reactions of an epoxide and an episulfide on aluminosilicates in the liquid phase
Authors: Fási András , Pálinkó István , Gömöry Ágnes , Kiricsi Imre 
Published: August 2006

AbstractThe ring opening reactions of propylene oxide (methyloxirane) or ethylene sulfide )thiirane) were studied in the liquid phase over HZSM-5, HY-FAU or AlMCM-41 at 363 K or 423 K and under 1 or 20 bar pressure in a batch reactor. The proportion of these routes were identified: (i) single C−O scission providing non-cyclic products, (ii) double C−O cleavage leading to the loss of the heteroatom, (iii) oligomerisation resulting in cyclic dimers and the trimer of thiirane and a non-cyclic dimer of methyloxirane. The reaction pathway depended on the conditions and the solid acids used. Findings are compared to those in the gas phase over the same solid acids. Transformation mechanisms are also suggested.
Study of catalase immobilized on a silicate matrix for non-aqueous biocatalysis
Authors: Horozova Elena , Dimcheva Nina 
Published: August 2006

AbstractCatalytic activity of catalase (CAT) immobilized on a modified silicate matrix to mediate decomposition of meta-chloroperoxibenzoic acid (3-CPBA) in acetonitrile has been investigated by means of quantitative UV-spectrophotometry. Under the selected experimental conditions, the kinetic parameters: the apparent Michaelis constat (KM), the apparent maximum rate of enzymatic reaction (Vmaxapp), the first order specific rate constants (ksp), the energy of activation (Ea) and the pre-exponential factor of the Arrhenius equation (Z0) were calculated. Conclusions regarding the rate-limiting step of the overall catalytic process were drawn from the calculated values of the Gibbs energy of activation ΔG*, the enthalpy of activation ΔH*, and the entropy of activation ΔS*.
2-[3-(Trifluoromethyl)phenyl]furo[3,2-b]pyrroles: synthesis and reactions
Authors: Gajdoš Peter , Pavlíková Soňa , Bureš Filip , Krutošíková Alžbeta 
Published: August 2006

AbstractThe synthesis and reactions of methyl 2-[3-(trifluoromethyl)phenyl]-4H-furo[3,2-b]pyrrole-5-carboxylate (1a) are described. Upon reaction with methyl iodide, benzyl chloride, or acetic anhydride, this compound gave N-substituted products 1b-d. By hydrolysis of compounds 1a-c, the corresponding acids 2a-c were formed, or by reaction with hydrazine-hydrate, the corresponding carbohydrazides 3a-c were formed. By heating 2-[3-(trifluoromethyl)phenly]-4H-furo[3,2-b]pyrrole-5-carboxylic acid (2a) in acetic anhydride, 4-acetyl-2-[3-(trifluoromethyl)phenyl]furo[3,2-b]pyrrole (4) was formed. By hydrolysis of 4, 2-[3-(trifluoromethyl)phenyl]-4H-furo[3,2-b]pyrrole (5a) was formed, and reactions with methyl iodide or benzyl chloride gave N-substituted products 5b-c. The reaction of 4 with dimethyl butynedioate gave substituted benzo[b]furan 6. Compound 3a reacted with triethyl orthoesters giving 7a-c, which afforded with phosphorus (V) sulphide the corresponding thiones 8a-c. The thiones 8a-c reacted with hydrazine hydrate to form hydrazine derivatives 9a-c. The reaction of triethyl orthoformiate with compounds 9a-c led to furo[2′,3′: 4,5]pyrrolo[1,2-d][1,2,4]triazolo[3,4-f][1,2,4]triazines 10a-c. Hydrazones 11a-c were formed from 3a-c and 5-[3-(trifluoromethyl)phenyl]furan-2-carboxaldehyde. The effect of microwave irradiation on some condensation reactions was compared with “classical” conditions. The results showed that microwave irradiation shortens the reaction time while affording comparable yields.
Oxidation of some catecholamines by sodium N-chloro-p-toluenesulfonamide in acid medium: A kinetic and mechanistic approach
Authors:   Puttaswamy, Jagadeesh R. , Vaz Nirmala 
Published: August 2006

AbstractThe kinetics of the oxidation of five catecholamines viz., dopamine (A), L-dopa (B), methyldopa (C), epinephrine (D) and norepinephrine (E) by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in presence of HClO4 was studied at 30±0.1 °C. The five reactions followed identical kinetics with a first-order dependence on [CAT]o, fractional-order in [substrate]o, and inverse fractional-order in [H+]. Under comparable experimental conditions, the rate of oxidation of catecholamines increases in the order D>E>A>B>C. The variation of ionic strength of the medium and the addition of p-toluenesulfonamide or halide ions had no significant effect on the reaction rate. The rate increased with decreasing dielectric constant of the medium. The solvent isotope effect was studied using D2O. A Michaelis-Menten type mechanism has been suggested to explain the results. Equilibrium and decomposition constants for CAT-catecholamine complexes have been evaluated. CH3C6H4SO2NHCl of the oxidant has been postulated as the reactive oxidizing species and oxidation products were identified. An isokinetic relationship is observed with β=361 K, indicating that enthalpy factors control the reaction rate. The mechanism proposed and the derived rate law are consistent with the observed kinetics.
Kinetic study of adsorption of some biocompounds at the oil/water interface
Authors: Tomoaia Gheorghe , Tomoaia-Cotisel Andrada , Tomoaia-Cotisel Maria , Mocanu Aurora 
Published: August 2006

AbstractThe adsorption kinetics of some local anesthetics, like dibucaine and tetracaine, and of stearic acid from bulk solutions at the oil/water interface was studied by using the pendent drop and ring methods. The anesthetics were dissolved in aqueous solutions (pH 2), and the fatty acid was dissolved in benzene, each biocompound at several different concentrations in bulk solutions. Kinetic equations for Langmuir mechanism of adsorption at oil/water interface were tested. The kinetic analysis shows that Langmuir kinetic approach describes the dynamic interfacial pressures within the limits of the experimental errors over a wide range of time and for different surfactant concentrations in bulk solutions. It is also concluded that this approach allows the calculation of the ratio of the adsorption and desorption rate constants of these biocompounds at the oil/water interface. Obtained results are in substantial agreement with earlier reported data for the surfactant adsorption as, well as with their molecular structure.
Density functional studies of the dipole polarizabilities of the linear polyacenes benzene through nonacene
Authors: Hinchliffe Alan , Nikolaidi Beatrice , Soscún Machado Humberto 
Published: August 2006

AbstractWe report Ab Initio studies of the electric dipole polarizability of the linear polyacene series benzene through nonacene. A number of Ab Initio studies were done at different levels of theory for benzene, with all remaining Ab Initio calculations being at the B3LYP/6-311G(2d, 1p)//B3LYP/6-311+G(2d, 1p) level of theory. We find that the NN tensor component shows a constant increment of 20 atomic units per ring. AM1 and QSAR-quality empirical calculations show poor absolute agreement with the Ab Initio results but given excellent statistical correlation coefficients with the Ab Initio values. This implies that the results of such cheaper calculations can be suitably scaled for predictive purposes.
Indirect spectrophotometric determination of gentamicin and vancomycin antibiotics based on their oxidation by potassium permanganate
Authors: El-Didamony Akram , Amin Alaa , Ghoneim Ahmed , Telebany Ayman 
Published: August 2006

Abstract
Four simple, accurate, sensitive and economical procedures (A–D) for the estimation of gentamicin sulphate and vancomycin hydrochloride, both in pure form and in pharmaceutical formulations have been developed. The methods are based on the oxidation of the studied drugs by a known excess of potassium permanganate in sulphuric acid medium and subsequent determination of unreacted oxidant by reacting it with amaranth dye (method A), acid orange II (method B), indigocarmine (method C) and methylene blue (method D), in the same acid medium at a suitable λmax=521, 485, 610 and 664 nm, respectively. The reacted oxidant corresponds to the drug content. Regression analysis of Beer-Lambert plots showed good correlations in the concentration ranges 4–8, 3–8, 4–9 and 5–9 µg ml−1 with gentamicin and 4–8, 1.5–4, 1.5–4 and 3.5–5.5 µg ml−1 with vancomycin for methods A, B, C, and D, respectively. The molar absorptivity, sandell sensitivity, detection and quantification limits were calculated. The stoichiometric ratios for the cited drugs were studied. The optimum reaction conditions and other analytical parameters were evaluated. The influence of the substance commonly employed as excipients with these drugs were studied. The proposed methods were applied to the determination of these drugs in pharmaceutical formulations. The results have demonstrated that the methods are equally accurate and reproducible as the official methods.
Synthesis and electronic properties of pentacene derivatives as promising n-type semiconductor candidates
Authors: Liu Chengbin , Tang Yanhong , Nie Shuming 
Published: August 2006

Abstract
Two pentacene derivatives 1 and 2 were synthesized from the Diels-Alder reactions of furan derivatives with 1,4-benzoquinone. They were characterized by the methods of 1H — nuclear magnetic resonance spectroscopy (1H-NMR), matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS), ultraviolet and visible spectrophotometry (UV-VIS), photoluminescence (PL) spectrometry and cyclic voltammetry (CV). The energy gaps of 1 and 2, taken directly from spectroscopic measurements, are broad as 2.72 and 2.46 eV, leading to blue and greenish blue photoluminescence, respectively. The LUMO and HOMO energy levels are −2.77 and −5.49 eV for 1, and −2.91 and −5.37 eV for 2, respectively. The low energy levels make both 1 and 2 good air-stabilities and promising n-type semiconductor candidates for use in organic electronics.
Hydrogen-bonded assembly and binding affinity of the multi-point acceptor and isophthalic acid
Authors: Xu Lingjia , Zhu Liangliang , Wu Shi , Chen Xiaopeng , Teng Qiwen 
Published: August 2006

Abstract
Supermolecular complexes formed by oligophenyleneethynylene derivatives and isophthalic acid were studied using AM1 method to obtain binding energy. Electronic spectra and IR spectra of the complexes were calculated by INDO/CIS and AM1 methods based on AM1 geometries. Results indicated that the dimer could be formed by the monomers via hydrogen bonding because of the negative binding energy. Binding energy of the complexes was affected by electronegativity and steric effects of the substituents. The first UV absorptions and IR frequencies of N-H bonds of the complexes were both red-shifted compared with those of the monomers. The complexes could bind small molecules via hydrogen bonds, resulting in the change in UV absorptions and an increase in IR frequencies of N-H bonds.
Towards relativistic ECP / DFT description of chemical bonding in E112 compounds: spin-orbit and correlation effects in E112X versus HgX (X=H, Au)
Authors: Zaitsevskii Andréi , Rykova Elena , Mosyagin Nikolai , Titov Anatoly 
Published: August 2006

Abstract
The relativistic effective core potential (RECP) approach combined with the spin-orbit DFT electron correlation treatment was applied to the study of the bonding of eka-mercury (E112) and mercury with hydrogen and gold atoms. Highly accurate small-core shape-consistent RECPs derived from Hartree-Fock-Dirac-Breit atomic calculations with Fermi nuclear model were employed. The accuracy of the DFT correlation treatment was checked by comparing the results in the scalar-relativistic (spin-orbit-free) limit with those of high level scalar-relativistic correlation calculations within the same RECP model. E112H was predicted to be slightly more stable than its lighter homologue (HgH). The E112-Au bond energy is expected to be ca. 25–30 % weaker than that of Hg-Au. The role of correlations and magnetic (spin-dependent) interactions in E112-X and Hg-X (X=H, Au) bonding is discussed. The present computational procedure can be readily applied to much larger systems and seems to be a promising tool for simulating E112 adsorption on metal surfaces.
Phenotypic characterisation of extreme growth-selected mouse lines: An important prerequisite for future QTL analysis
Authors: Renne Ulla , Dietl Gerhard , Langhammer Martina , Rehfeldt Charlotte , Nürnberg Karin , Kuhla Siegfried , Bünger Lutz 
Published: August 2006

AbstractA unique set of seven mouse lines, long-term selected for high growth, from different laboratories around the world has been comprehensively compared to evaluate these resources for future QTL and gene mapping for growth traits. The heaviest line (DUH) was 40% (males) to 44% (females) heavier than the smallest line (ROH) at birth, and 105% (males) to 114% (females) heavier at 98 d. Body conformation (body length and width, body areas), body composition (dry matter, fat, fatty acid composition, organ weights), and skeletal muscle cellularity also differed substantially. DUH was more than 20% longer (12.3 cm) compared to the shortest line ROH (9.7 cm). DAH (22.5%) had the highest percentage of gonadal fat and the leanest was BEH (7.7%). Line BEH (0.49 g) showed the highest weight for the left M. rectus femoris, which was 2.1 times higher, compared to ROH (0.23 g). These results suggest that different alleles, and possibly different physiological pathways, have contributed to the selection response in the different lines. Therefore these selection lines are an important tool with which to identify the genetic and physiological basis of growth as they may contain many, if not all, growth promoting alleles.
Sugar Bingeing in Rats
Authors: M. Avena Nicole , Rada Pedro , Hoebel Bartley G. 
Published: August 2006

AbstractBingeing behavior is characteristic of many eating disorders. This unit describes an animal model of sugar bingeing. This model has been used successfully to elicit behavioral and neurochemical signs of sugar dependence in rats, e.g., indices of bingeing, withdrawal, increased intake after abstinence (deprivation effect), cross‐sensitization with amphetamine, and increases in dopamine release in the nucleus accumbens due to repeated bingeing.
One‐Dimensional SDS Gel Electrophoresis of Proteins
Authors: Gallagher Sean R. 
Published: August 2006

AbstractElectrophoresis is used to separate complex mixtures of proteins (e.g., from cells, subcellular fractions, column fractions, or immunoprecipitates), to investigate subunit compositions, and to verify homogeneity of protein samples. It can also serve to purify proteins for use in further applications. In polyacrylamide gel electrophoresis, proteins migrate in response to an electrical field through pores in a polyacrylamide gel matrix; pore size decreases with increasing acrylamide concentration. The combination of pore size and protein charge, size, and shape determines the migration rate of the protein. In this unit, the standard Laemmli method is described for discontinuous gel electrophoresis under denaturing conditions, that is, in the presence of sodium dodecyl sulfate (SDS). Both full‐size and minigel formats are detailed. Several modifications are provided for specific applications. For separation of peptides and small proteins, the standard buffers are replaced with either a Tris‐tricine buffer system or a modified Tris buffer in the absence of urea. Continuous SDS‐PAGE is a simplified method in which the same buffer is used for both the gel and electrode solutions and the stacking gel is omitted. Other protocols cover the preparation and use of ultrathin gels and gradient gels, and the simultaneous preparation of multiple gels.
Collection of Blood and Plasma from the Mouse
Authors: Argmann Carmen A. , Auwerx Johan 
Published: August 2006

AbstractThere are many elements in plasma that can act as surrogate markers of the physiological well‐being of a mouse, thus making the collection of blood and plasma a general technique with many applications in mouse phenotyping. For example, the presence of certain enzymes in plasma can serve as markers of tissue toxicity (AST, ALT) and general function, and the more sophisticated lipid and lipoprotein profile tests (cholesterol, LDL) can point to dyslipidemias. As many of the tests available to measure these parameters have been adapted to automated systems in a high‐throughput fashion, they have become part of the first line of screening protocols in mouse phenotyping. In this section, general techniques associated with collection and processing of blood are described.
Internet Resources in Medical Genetics
Authors: Pagon Roberta A. 
Published: August 2006

AbstractThis unit presents an overview of the most commonly used, Web‐based information resources for (1) clinicians seeking to apply molecular genetic testing to patient care (see ) or to understand the molecular basis of inherited diseases (see ), (2) consumers seeking advocacy information (see ) or scientific and management information (see , , , , , and ), and (3) genetics professional societies.
Detecting Mutations in the APC Gene in Familial Adenomatous Polyposis (FAP)
Authors: Hegde Madhuri R. , Roa Benjamin B. 
Published: August 2006

AbstractHereditary forms of colorectal cancer (CRC) account for up to 5% of total cases. Familial adenomatous polyposis (FAP) is an autosomal dominant condition affecting nearly 1 in 5000 people and accounts for only about 1% of all CRCs. It is characterized by the progressive development of hundreds to thousands of adenomatous colon polyps. The gene associated with FAP (APC) contains 15 exons in the coding region. A scanning approach for large genes is reasonable, but some standard techniques have limited analytical sensitivity. The method described here, using DHPLC as mutation scanning approach for medium‐throughput DNA sequence analysis, is largely considered to be the gold standard for point mutation analysis, and can be optimized for high‐throughput testing. Detection of deletion and duplication mutations refractory to sequencing have been described using real‐time quantitative PCR for dosage analysis. Technical strategies for mutation detection in the APC gene are presented in this chapter.