bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of Spheron as a matrix for affinity chromatography of NAD-dependent dehydrogenases
Authors: Kovář Jan , Škodová Alena , Turánek Jaroslav
Published: September 2010

The paper compares several methods of coupling common ligands of dehydrogenases, viz. N6-[(6-aminohexyl)carbamoylmethyl]-AMP and N6-[(6-aminohexyl)carbamoylmethyl]-NAD, to a hydrophilic macroporous glycolmethacrylate gel, Spheron. The affinants coupled best to a CNBr-activated gel and to a gel with hydrazine groups (after activation with nitrous acid). The affinity properties of gels based on Spheron and on Sepharose 4B were similar ( the stability and separation efficiency were almost identical, the binding capacity and the recovery of dehydrogenase activity were somewhat better with the Sepharose). The materials based on Spheron were used in several separation experiments, viz. separation of lactate dehydrogenase form albumin, separation of lactate dehydrogenase from alcohol dehydrogenase under different conditions and separation of isoenzymes of lactate dehydrogenase. Spheron 300 with a coupled affinant was also employed in an attempt to purify a crude alcohol dehydrogenase.
Hydrolysis of manganese carbides Mn5C2 and Mn23C6
Authors: Karen Pavel , Hájek Bohumil
Published: September 2010

Diffractographically pure manganese carbides Mn5C2 and Mn23C6 were hydrolyzed with water at 25 and 60 °C. Based on the model of contracting spherical particles in the carbide powder particulate system, the corrosion rates were calculated from the course of gas evolution during the hydrolysis; the values obtained were as follows in μm/h: Mn5C2: 1.2 ± 0.4 at 25 °C and 10 ± 3 at 60 °C, and Mn23C6: 0.15 ± 0.01 at 25 °C and 2.2 ± 0.2 at 60 °C. The hydrolysis gives rise to hydrogen and a concentration-decreasing sequence of predominantly saturated hydrocarbons, the fraction of C2 and higher hydrocarbons being about 6 times lower for Mn23C6 than for Mn5C2. The hydrogen and hydrocarbon contents of the mixture after hydrolysis are consistent with the assumed reaction course, where the adsorbed active hydrogen, formed during the hydrolysis reaction due to the metallic nature of the carbide, partly reacts with the methane arising from the hydrolysis of the C1 groups in the carbide and partly combines to molecular hydrogen.
Determination of the Mark-Houwink constants by gel permeation chromatography with correction for longitudinal spreading
Authors: Kubín Miroslav
Published: September 2010

The determination of the Mark-Houwink constants using gel permeation chromatography data, based on a known universal calibration dependence and the recorded chromatograms of one or several characterized polydisperse polymer samples, has been modifies by including correction factors for the longitudinal spreading. Verification by means of artificial, computer generated chromatograms shows that the new procedure considerably raises the accuracy and reliability of the results obtained.
Mechanism and kinetics of grafting of polypropylene by water-soluble monomers in emulsion
Authors: Citovický Pavol , Mikulášová Darina , Štaudner Emil , Chrástová Viera , Beniska Jozef
Published: September 2010

Oxidized isotactic polypropylene powder was grafted at 30 °C in aqueous emulsion with water-soluble monomers such as acrylic acid and acrylamide. The decomposition of the polypropylene -O-O- groups, initiating the graft polymerization, proceeds due mainly to the effect of the activator used, viz. a chelate of iron(II), and is favoured by the monomer and the necessarily present water-insoluble liquid phase. The grafting reaction order with respect to the concentration of the water-soluble monomer is 2 and higher. A mechanism and kinetics are suggested for the polypropylene grafting by these water-soluble monomers, involving the concept of presence of long-living radicals bonded to the solid polypropylene phase.
The crystal and electron structure of 3-benzylbenzothiazolium bromide
Authors: Kellö Eleonóra , Kettman Viktor , Miertuš Stanislav , Vrábel Viktor , Konečný Václav
Published: September 2010

3-Benzylbenzothiazolium bromide forms colourless needle-like crystals of monoclinic system, space group P21/c, with cell parameters a = 8.315(6), b = 12.323(9), c = 13.140(11) . 10-10 m, β = 103.79(6)0, and Z = 4. The phase problem was solved by heavy atom method and structure was refined by full matrix least-squares method with anisotropic thermal parameters to final R = 0.105 and wR = 0.113. The crystal structure is formed by monomer non-centrosymmetric units, among them weak non-bonding interactions of type Br...S, Br...N and also intermolecular interactions of van der Waals type C...S, C...N, C...C, and C...H-C are observed. Values of angles C6N1C8 122.2(6)°, C7N1C8 122.5(7)°, and C6N1C7 115.4(7)° correspond to sp2 type of nitrogen hybridization and they support its trigonal planar configuration. The CNDO/2 quantum chemistry method for electron structure calculation was used. Calculations were concentrated to partial optimization of two dihedral angles and to evaluation of indices describing the electron density distribution in the molecule of the title compound. The torsion angles for the most stable conformation are in a good agreement with the X-ray structure analysis results.
Vapour-liquid equilibrium in the water(1)-morpholine(2) system at the pressures of 50 and 75 kPa
Authors: Sovová Miroslava , Boublík Tomáš
Published: September 2010

Vapour-liquid equilibrium in the water(1)-morpholine(2) system was determined experimentally at the pressures of 50 and 75 kPa. The data were correlated by the Redlich-Kister equation. The dependence od the excess Gibbs free energy on temperature was expressed by a linear dependence of the first parameter of the two-parameter equation on the reciprocal absolute temperature.
A study of the medium effect of mixed solvents; The cyclohexane-nitrobenzene system
Authors: Nevěčná Taťjana , Bekárek Vojtěch
Published: September 2010

Rate constants of the reaction of triethylamine with ethyl iodide (at 293.15, 313.15, 323.15, and 333.45 K) and wavenumbers of the longest wavelength band maxima of 4-nitroso-N,N-dimethylaniline and 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenoxide were measured in nitrobenzene and thirteen mixtures of nitrobenzene with cyclohexane. The activation characteristics of the reaction of triethylamine with ethyl iodide in these media were calculated, and the correlations of rate constants and spectral data were carried out with functions of relative permittivity and refractive index of the media used and mutually with each other.
Oxidation of cumene by molecular oxygen on heterogenized cobalt catalysts
Authors: Setínek Karel , Drapáková Stanislava , Prokop Zdeněk
Published: September 2010

In the oxidation of cumene to cumene hydroperoxide by molecular oxygen in the liquid phase, the cobalt(II) catalysts heterogenized on organic cation exchangers are active only if acid functional groups of the exchanger which bind cobalt ions show medium or weak acidity. The catalysts based on strongly acidic ion exchangers are inactive and, contrary to the above catalysts, they catalyze decomposition of the cumene hydroperoxide present in the reaction mixture to phenol and acetone.
Electrochemical reactions with participation of stable nitrosyl radicals of piperidine line
Authors: Fiošin M. Ya. , Avruckaya I. A. , Bogdanova N. P. , Surov I. I.
Published: September 2010

Article in Russian
New method of preparation of cardioglycoside hemisuccinates
Authors: Pouzar Vladimír , Černý Ivan , Drašar Pavel , Havel Miroslav
Published: September 2010

An indirect method for preparation of hemisuccinates (hydrogen butanedioates) is described, consisting in reaction of hydroxy derivatives with 2-(trimethylsilyl)ethyl hemisuccinate (I) followed by removal of the 2-(trimethylsilyl)ethyl group from the mixed succinate with tetrabutylammonium fluoride. It has been applied to the synthesis of hemisuccinates derived from cholesterol (II), (20E)-21-methoxycarbonylpregna-5,20-dien-3β-ol (V), digitoxigenin (XII), digitoxin (XV) and digoxin (XVIII). The method, however, is not suitable for the preparation of estrone hemisuccinate X which is cleaved with tetrabutylammonium fluoride to give estrone(VIII).
Polarographic and voltammetric determination of N,N-dimethyl-4-aminoazobenzene
Authors: Barek Jiří , Hrnčíř Roman
Published: September 2010

Conditions were found for the determination of chemical carcinogen N,N-dimethyl-4-aminoazobenzene by TAST and differential pulse polarography, fast scan differential pulse voltammetry and linear sweep voltammetry at a hanging mercury drop electrode in a mixed aqueous-methanolic medium. The detection limit of the last two methods, approximately 10-8 mol l-1, can be further lowered by preliminary accumulation of the substance to be determined by adsorption at a working electrode. The applicability of these methods to the analysis of biological materials, directly or combined with an extraction, was demonstrated.
Reaction of 2-butenolide and 4-bromo-2-butenolide with 5-aryl-2-furaldehydes and thiolates
Authors: Kaklyugina Tatyana Ya. , Badovskaya Larisa A. , Sorotskaya Ludmila N. , Kozhina Nadezhda D. , Jurášek Adolf , Kada Rudolf , Kováč Jaroslav , Kulnevich Vladimír G.
Published: September 2010

Condensation of 2-butenolide with 5-(4-X-phenyl)-2-furaldehydes (X = H, CH3, OCH3, Br, Cl, NO2) in methanol in the presence of piperidine as catalyst afforded the corresponding 4-[5-(4-X-phenyl-2-furfurylidene)]-2-butenolides. As shown by 1H NMR spectra, the reaction afforded mixtures of Z- and E-isomers which on crystallization were isomerized to the stable Z-isomers (except when X = NO2). 4-Bromo-2-butenolide reacted with sodium salts of 2-mercaptobenzoxazole and 2-mercaptobenzimidazole to give the corresponding 4-(benzazoyl-2-thio)-2-butenolides, probably by an anion-radical mechanism. With arene thiolates, no substitution of the bromo atom took place and the reaction afforded only the corresponding disulfides. The IR and 1H NMR spectra of the synthesized compounds are discussed.
Synthesis and properties of 4-alkylaminomethyl and 4-alkoxymethyl derivatives of 5-methyl-2-furancarboxylic acid
Authors: Štetinová Jarmila , Jurášek Adolf , Kováč Jaroslav , Dandárová Miloslava , Rajniaková Oľga
Published: September 2010

New β-substituted amines and ethers of the furan series (II-V) were prepared by reaction of methyl 4-bromomethyl-5-methyl-2-furancarboxylate (I) with nucleophiles such as pyrrolidine, piperidine, morpholine, N-phenylpiperazine, cyclohexylamine, 2-methylcyclohexylamine, N-ethylaniline, p-toluidine, ethanol, butanol and salicylaldehyde. The structure of the products was confirmed by their analytical and spectral data. Kovats indices I for the products were determined using gas-liquid chromatography.
Addition of C- and S-nucleophiles to acryloylferrocene and cinnamoylferrocene catalysed by KF/Al2O3
Authors: Kaluz Štefan , Toma Štefan
Published: September 2010

Michael addition of a series of C- and S-nucleophiles to acryloyl- and cinnamoylferrocene catalysed by KF/Al2O3 has been studied. In general, the reaction proceeded quantitatively and in shorter reaction time compared to the common procedure. The synthesis of acryloylferrocene has been improved.
Direct esterification of α-methoxy-α-(trifluoromethyl)phenylacetic acid
Authors: Streinz Ludvík , Valterová Irena , Wimmer Zdeněk , Buděšínský Miloš , Šaman David , Kohoutová Jitka , Romaňuk Miroslav , Vrkoč Jan
Published: September 2010

Esters of α-methoxy-α-(trifluoromethyl)phenylacetic acid (Mosher acid, MTPA) were prepared in good yields from alcohols and the free acid Ia using 2-chloro-1-methylpyridinium iodide (II) as condensing agent.
A novel synthesis of thiazolyl, imidazothiadiazolyl, and thiadiazinyl-2H-1-benzopyran-2-ones
Authors: Rajeswar Rao V. , Rao M. S. , Padmanabha Rao T. V.
Published: September 2010

3-Acetylcoumarins I with arylthiourea in the presence of iodine gave substituted 3-(2-arylamino-4-thiazolyl)-2H-1-benzopyran-2-ones (IIa-IIc). The structures of these products have been confirmed and they were converted into acetyl derivatives (IId-IIf). Condensation of various 3-(2-bromoacetyl)-2H-1-benzopyran-2-ones (III) with 2-amino-6-substituted thiadiazoles IV in the presence of ethanol and dimethylformamide yielded substituted 3-(2-substituted imidazo[2,1-b]thiadiazol-6-yl)-2H-1-benzopyran-2-ones (VI). Reaction of III with 3-substituted 4-amino-5-mercapto-S-triazole VII resulted in the formation of VIII in a single step.
Alkaloids from Papaver atlanticum BALL and Papaver glaucum BOISS. et HAUSKN.
Authors: Táborská Eva , Bochořáková Hana , Věžník František , Slavík Jiří , Dolejš Ladislav
Published: September 2010

In addition to the alkaloids previously found in the aerial part of P. atlanticum BALL, viz. protopine, rhoeadine (predominant constituents), rhoeagenine, stylopine, cryptopine, sanguinarine, magnoflorine and papaverrubines A, B, E and D, we have now isolated the tertiary bases isothebaine, scoulerine, corytuberine and a new quaternary alkaloid 13β-hydroxy-N-methylstylopinium hydroxide (I). The presence of papaverrubine B and muramine was also detected (TLC). The contents of the bases in the roots of P. atlanticum were found similar to those in the aerial part. Magnoflorine was isolated from the roots in a considerable yield. The dominant alkaloids isolated from P. glaucum BOISS. et HAUSKN. were glaudine and glaucamine; they were accompanied by protopine, papaverrubine B and traces of sanguinarine, coptisine and papaverrubine C. Magnoflorine and corytuberine have been isolated from this species for the first time and the presence of allocryptopine, cryptopine, corydine, isocorydine and papaverrubines D and H has been demonstrated.
Binding of lead and copper(II) cations to hemicelluloses of rye bran
Authors: Kohn Rudolf , Hromádková Zdena , Ebringerová Anna
Published: September 2010

Several fractions of acid hemicelluloses isolated from rye bran were characterized by molar ratios of saccharides (D-Xyl, L-Ara, D-Glc, D-Gal) and 4-O-methyl-D-glucuronic acid and protein content. Binding of Pb2+ and Cu2+ ions to these acid polysaccharides was considered according to function (M)b = f([M2+]f), expressing the relationship between the amount of metal (M)b bound to 1 g of the substance and the concentration of free ions [M2+]f in the equilibrium solution and according to the association degree β of these cations with carboxyl groups of uronic acid at a stoichiometric ratio of both components in the system under investigation. Acid hemicelluloses contained only a very small portion of uronic acid ((COOH) 0.05-0.18 mmol g-1); the model polysaccharide, 4-O-methyl-D-glucurono-D-xylan of beech, was substantially richer in uronic acid content ((COOH) 0.73 mmol g-1). Consequently, the amount of lead and copper bound to acid hemicelluloses is very small ((M)b 0.017-0.025 mmol g-1) at [M2+]f = 0.10 mmol l-1. On the other hand, much greater amount of cations ((M)f 0.09-0.10 mmol g-1) was bound to the glucuronoxylan. The association degree β was like with the majority of samples (β = 0.31-0.38). The amount of lead and copper(II) bound to acid hemicelluloses from rye bran is several times lower than that bound to dietary fiber isolated from vegetables (cabbage, carrot), rich in pectic substances.
Binding of calcium ions to 2,3-dicarboxy derivatives of pectic acid
Authors: Malovíková Anna , Kohn Rudolf
Published: September 2010

Using a two-step oxidation of pectic acid (85% of D-galacturonan in the preparation) a series of 2,3-dicarboxy derivatives (Na+ form) was prepared containing 4.2 to 8.5 mmol of carboxyl groups per gram (COOH g-1). After the centrifugation of the diluted suspensions of the Ca-salts of these polyacids the activity of the calcium counterions (aCa2+) was determined using the metallochromic indicator (tetramethylmurexide) and the activity coefficient γCa2+ was calculated. Using potentiometric titrations of polyacids with potassium and calcium hydroxides the decrease in electrostatic free enthalpy, Δ(Gel/N)KCa, of the cation exchange Ca2+ → 2 K+ was determined. In the course of the oxidation, degradation of the macromolecules took place, characterized by the limit viscosity number [η]. In spite of the considerable degradation, preparations with higher oxidation degrees display a high selectivity in the exchange of cations Ca2+ → 2 K+, similar to that determined recently by us in 2,3-dicarboxy derivatives of starch and amylose. The strong binding of Ca2+ ions to the investigated substances is also documented by very low activity coefficient values, γCa2+, ranging from 0.057 to 0.037.
Comments on spectrofluorometric assay of angiotensin-converting enzyme activity in blood plasma of different species
Authors: Shisheva Assia C. , Ikonomov Ognian C. , Sirakov Luben M.
Published: September 2010

The activity of the angiotension -converting enzyme (ACE) in human, dog, rabbit, and rat blood plasma was assayed by spectrofluorometric determination of the product liberated by enzymatic cleavage (L-His-L-Leu). In parallel experiments the hydrolysis of L-His-L-Leu by blood plasma was examined. The hydrolytic activity of rat blood plasma was high and therefore lower values of ACE activity were obtained; the use of the spectrofluorometric assay with rat blood plasma is therefore problematic. By contrast, L-His-L-Leu was not degraded by human, dog, and rabbit blood plasma and the spectrofluorometric determination of this peptide can thus be used to advantage to assay the ACE activity of blood plasma samples of these species.
Polarographic and voltammetric determination of 6-mercaptopurine and 6-thioguanine
Authors: Barek Jiří , Berka Antonín , Dempírová Ludmila , Zima Jiří
Published: September 2010

Conditions were found for the determination of 6-mercaptopurine (I) and 6-thioguanine (II) by TAST polarography, differential pulse polarography and fast-scan differential pulse voltammetry at a hanging mercury drop electrode. The detection limits were 10-6, 8 . 10-8, and 6 . 10-8 mol l-1, respectively. A further lowering of the detection limit to 2 . 10-8 mol l-1 was attained by preliminary accumulation of the determined substances at the surface of a hanging mercury drop.
Mathematical modelling of salt purification by recrystallization. Estimation of the recrystallization factor for countercurrent arrangement
Authors: Mayrhofer Benitto , Mayrhoferová Jana , Neužil Lubomír
Published: September 2010

In a previous paper a simple model was developed for salt purification by countercurrent recrystallization. Analysis of mass balances for a microcomponent provided a relation for the composition (purity) of the product as a function of the number of recrystallization stages and of recrystallization conditions reduced to a single parameter called the recrystallization factor. The problem can be readily solved if the dependence of the product purity on the number of recrystallization stages is to be established for a given recrystallization factor. Some difficulties arise when the product purity and maximum number of stages are fixed. For this variant, relations are derived from which the upper and lower limits for the recrystallization factor can be estimated. For recrystallization factors K > 2, this method is more accurate than the use of diagrams published previously. An example is given to illustrate the proposed method.
Vapour-liquid equilibrium in the benzene(1)-propionic acid(2)-acetic acid(3) ternary system
Authors: Malijevská Ivona , Perničková Helena , Ledvinka Karel , Doležal Bohuslav
Published: September 2010

Results of measurement of vapour-liquid equilibria in the benzene-propionic acid-acetic acid ternary system at normal pressure are presented. The activity coefficients were, within the framework of inaccuracies determined on the basis of the law of error propagation, subjected to a test of consistency and correlated by the Wilson equation. The experimental values of activity coefficients are compared with the values calculated on the basis of the Wilson equation with its constants obtained both from the ternary and from the binary data and with the values estimated by the UNIFAC method.
Mass spectrometric and electron spin resonance study of allylic peroxyl radicals in the gas-phase reaction between allylic radicals and dioxygen
Authors: Mach Karel , Nováková Jana , Hanuš Vladimír , Dolejšek Zdeněk
Published: September 2010

Mass spectrometric measurement of the pyrolyzed (790-1 030 K) mixture of 1,5-hexadiene or 2,5-dimethyl-1,5-hexadiene with dioxygen afforded no evidence for the presence of allylic peroxyl radicals or aldehydes in the gas phase though the allylic radicals were readily detected at low ionization potentials. On the other side, the electron spin resonance measurement revealed that the allylic radicals were converted quantitatively to allylic peroxyl radicals during condensation of pyrolytic mixtures at 77 K, and acrolein and methacrolein were found mass spectrometrically after thawing of the condensed pyrolytic material as stable products of the allylperoxyl and 2-methylallylperoxyl radical, respectively. These results are compatible with the temperature dependent dissociation equilibrium of the allylic peroxyl radicals. The allylic peroxyl radicals were trapped at 77 K using co-condensation with adamantane from the gas phase in yields as high as 30-50% of the radicals produced in pyrolysis. The electron spin resonance spectra showed partial motional freedom of the peroxyl radicals when they were trapped in the low-contaminated adamantane matrix at 77 K, but in matrices highly contaminated with the biallyl hydrocarbon and products of pyrolysis the ESR spectra indicated rigidly trapped peroxyl radicals. Free rotation of the allylic peroxyl radicals in both types of matrices occurred at 110 K.
Analysis of the oscillatory behaviour of an industrial reactor for oxonation of propene: The CSTR model
Authors: Horák Josef , Bělohlav Zdeněk , Rosol Petr , Madron František
Published: September 2010

The paper analyses the oscillatory states of an industrial reactor observed in the process aimed at enhancing its productivity. The model of a perfectly stirred continuous reactor was used for the analysis. Both the stable and the oscillatory states were found to have the same character while their stability depended on the ratio of the heat and mass capacities of the system. The model of the perfectly stirred reactor did not help us explain the observed instability unless a high value of the activation energy was used.
Deactivation of arenetitanium(II) bromoalane complexes in the cyclotrimerization of butadiene
Authors: Poláček Jindřich , Antropiusová Helena , Petrusová Lidmila , Mach Karel
Published: September 2010

The C6H6.Ti(II)(AlBr4)2 (Ib) catalyst deactivates during the butadiene cyclotrimerization to give a solid containing all titanium (mostly as TiBr3) and a mixture of AlBr3 and RAlBr2 compounds dissolved in benzene. The residual cationic catalytic activity of the deactivated Ib system is due to presence of AlBr3. In contrast to TiCl3, the deactivated Ib system and the model system TiBr3 + AlBr3 are not activated by the addition of EtAlCl2 in the presence of butadiene: the highly active benzenetitanium(II) system is re-constituted only after reduction of TiBr3 with Et3Al followed by the addition of EtAlCl2. The addition of Et2AlBr to Ib accelerates the deactivation of the system. Deactivation products of this system contain mainly Ti(II) species which forms benzenetitanium(II) catalytic system after addition of EtAlCl2. All the EtAlCl2 reactivated systems produce (Z, E, E)-1,5,9-cyclododecatriene with high catalytic stability and considerable selectivity (>90%). This behaviour points to the catalysis by benzenetitanium(II) chloroalane complexes containing only low amount of bromine atoms and ethyl groups.
Hydrogenation-dehydrogenation and cleavage functions of hydrorefining catalysts studied by the reaction of tetrahydrothiophene
Authors: Drahorádová Alexandra , Zdražil Miroslav
Published: September 2010

The reaction of tetrahydrothiophene in a stream of nitrogen was used to study the relations between dehydrogenation and C-S cleavage reactions on sulphided Co-Mo/Al2O3 catalysts. The course of the reaction was compared for Co-Mo catalysts supported on alumina and activated carbon, for alumina alone as well as for a Pt/C catalyst. The effect of substitution of nitrogen for hydrogen, of the addition of water to the feed, of pre-sulphidation of catalysts and their deactivation by coking on the rate and selectivity of the reaction were also investigated. The results showed that hydrogenation-dehydrogenation and dehydrosulphurization activity of the sulphide catalysts have the same origin. Hydrogen accelerates dehydrosulphurization on the sulphide catalysts by removing sulphur and unsaturated hydrocarbons formed on catalyst surface by C-S bond cleavage reactions.
Reactions of methyl ester of 5-amino-2-furancarboxylic acid with ethyl esters of orthoacids
Authors: Štibrányi Ladislav , Peeva Milena , Kozempelová Zdena , Leško Ján , Kováč Jaroslav
Published: September 2010

By the reaction of the title compound with ethyl esters of orthoformic, orthoacetic, orthocarbonic, and pyrocarbonic acids, respectively, formimidate II, acetimidate III, imidocarbonate IV and carbamides V were prepared. IR, UV spectra were measured and 1H NMR and mass spectra were interpreted.
Mass spectral studies of aromatic aza analogues of juvabione
Authors: Mahajan R. K. , Gupta Neelam , Uppal Satinder K.
Published: September 2010

Mass spectra of title compounds I-VI have been studied with a view to comparing the fragmentation pattern of secondary amides in different structural environments.
Constituents of frontal gland secretion of peruvian termites Nasutitermes ephratae
Authors: Valterová Irena , Vašíčková Soňa , Buděšínský Miloš , Vrkoč Jan
Published: September 2010

The defense secretion of Nasutitermes ephratae soldiers was analyzed and its constituents were identified. The volatile fraction contains monoterpenic hydrocarbons α-pinene, camphene, sabinene, β-pinene, myrcene, 4-carene, 3-carene, α-terpinene, limonene, γ-terpinene, β-phellandrene, and terpinolene. From the non-volatile fraction four alcohols derived from trinervitane skeleton were isolated: 1(15),8(19)-trinervitadien-3α-ol (I), 1(15),8(19)-trinervitadien-2β,3α-diol (II) and its 2α,3α- (III) and 2α,3β- (IV) isomers. 3α-Hydroxy-1(15),8(19)-trinervitadien-2-one (V), which was also isolated, is probably an artefact formed during the work-up of the extract. The structure of 3β-hydroxy-1(15),8(19)-trinervitadien-2-one (VI) was determined on the basis of mass, IR and 1H NMR spectra, comparison with model compounds and analogy with the literature. The absolute configuration of the trinervitane skeleton was studied by CD spectra of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)praseodymium complexes of the 2,3-diols II-IV and by the 1H NMR spectra of esters of the alcohol I with (R)- and (S)-α-methoxy-α-(trifluoromethyl)phenylacetic acid. The results obtained by both methods are identical and confirm the earlier suggested absolute configuration of the trinervitane skeleton.
Are there risk factors for snowboard injuries? A case-control multicentre study of 559 snowboarders
Authors: Hasler Rebecca M , Berov Simeon , Benneker Lorin , Dubler Simon , Spycher Jonathan , Heim Dominik , Zimmermann Heinz , Exadaktylos Aristomenis K
Published: September 2010

Objective

To analyse risk factors leading to injuries during snowboarding.

Design

A case–control multicentre survey of injured and non-injured snowboarders.

Setting

One tertiary and two secondary trauma centres in Bern, Switzerland.

Methods

All snowboard injuries admitted to our tertiary and two affiliated secondary trauma centres from 1 November 2007 to 15 April 2008 were analysed on the basis of a completed questionnaire incorporating 15 variables. The same questionnaire was applied in non-injured controls at valley stations after a snowboarding day during the same period. A multiple logistic regression was performed (dichotomous variables). Patterns of combined risk factors were calculated by inference trees.

Results

306 patients and 253 controls were interviewed. The following variables were statistically significant for the injured patients: low readiness for speed (OR 0.20, 95% CI 0.06 to 0.64, p=0.0037), bad weather/visibility (OR 19.06, 95% CI 2.70 to 134.73, p=0.0031) and old snow (OR 0.11, 95% CI 0.02 to 0.68, p=0.0323). Not wearing a helmet and riding on icy slopes emerged as a combination of risk factors associated with injury.

Conclusions

Several risk factors and combinations exist, and different risk profiles were identified. Future research should be aimed at more precise identification of groups at risk and developing specific recommendations for each group—for example, a snow-weather conditions index at valley stations.
INVARIANT MANIFOLDS FOR COMPETITIVE DISCRETE SYSTEMS IN THE PLANE
Authors: KULENOVIĆ M. R. S. , MERINO ORLANDO
Published: September 2010

Let T be a competitive map on a rectangular region [Formula: see text], and assume T is C1 in a neighborhood of a fixed point [Formula: see text]. The main results of this paper give conditions on T that guarantee the existence of an invariant curve emanating from [Formula: see text] when both eigenvalues of the Jacobian of T at [Formula: see text] are nonzero and at least one of them has absolute value less than one, and establish that [Formula: see text] is an increasing curve that separates [Formula: see text] into invariant regions. The results apply to many hyperbolic and nonhyperbolic cases, and can be effectively used to determine basins of attraction of fixed points of competitive maps, or equivalently, of equilibria of competitive systems of difference equations. These results, known in hyperbolic case, have been used to determine the basins of attraction of hyperbolic equilibrium points and to establish certain global bifurcation results when switching from competitive coexistence to competitive exclusion. The emphasis in applications in this paper is on planar systems of difference equations with nonhyperbolic equilibria, where we establish a precise description of the basins of attraction of finite or infinite number of equilibrium points.
CONTROLLED HENON SYSTEM AND ITS CRYPTOGRAPHIC APPLICATIONS
Authors: KANSO ALI
Published: September 2010

This paper proposes a modification of the controlled chaotic Henon system suggested in [Li et al., 2004]. The dynamics of the proposed and existing 2-D systems are analyzed and new chaotic attractors are found in them. We show that these systems exhibit chaotic behavior for a wide range of control parameters. We also construct a chaotic modulation scheme with feedback based on a single controlled chaotic Henon system for use in cryptographic applications. The efficiency of this communication scheme is analyzed and is shown to provide a high level of security, resulting from the proper use of controllers. Furthermore, we propose a technique for generating random-like binary digits from the suggested controlled chaotic Henon systems. Unlike binary digits generated by chaotic Henon systems which usually do not possess random-like properties, the digits generated here are shown (numerically using the NIST statistical test suite) to possess excellent random-like properties. Furthermore, the generated bit sequences are demonstrated to have a large period, which may have useful applications in cryptography.
BRAID SOLUTIONS TO THE ACTION OF THE GIN ENZYME
Authors: CABRERA-IBARRA HUGO , LIZÁRRAGA-NAVARRO DAVID A.
Published: September 2010

The topological analysis of enzymes, an active research topic, has allowed the application of the tangle model of Ernst and Sumners to deduce the action mechanism of several enzymes, modeled as 2-string tangles. By first deriving some results in the theory of 3-braids, in this paper we analyze knotted and linked products of site-specific recombination mediated by the Gin DNA invertase, an enzyme that involves 3-string tangles. Provided that the 3-tangles involved are 3-braids, we determine four families of solutions to its action, two families for each of the directly and inversely repeated site cases. For each case, one of the given solutions had not previously been reported in the related literature. These solutions were found using a computer algorithm, based on our theoretical results, which allows one to solve tangle equations under the assumption that the product of two or more rounds of recombinations is known.
ADVANCING A TYPOLOGY OF OPEN INNOVATION
Authors: GIANIODIS PETER T. , ELLIS S. C. , SECCHI E.
Published: September 2010

Interest in the concept of open innovation (OI) has increased during recent years; yet, this line of inquiry remains limited due to the lack of a more comprehensive conceptual framework. As a first step toward a unifying framework, we provide a critical review of previous research on the conceptualization, antecedents, and consequences of OI. We then offer a typology describing four OI strategies: (i) innovation seeker, (ii) innovation provider, (iii) intermediary, and (iv) open innovator, which emerge through unique combinations of sources of innovation, firm attributes, and mechanisms of inter-organizational exchange, and produce varying outcomes. Finally, we discuss our typology's implications for theory and practice, and advance potential research avenues.
PROCUREMENT PROCEDURES FOR SUPPLIER INTEGRATION AND OPEN INNOVATION IN MATURE INDUSTRIES
Authors: SJÖDIN DAVID RÖNNBERG , ERIKSSON P. E.
Published: September 2010

The development and installation of new process equipment in production plants typically require strong collaborative efforts by a process firm and its equipment suppliers. However, existing knowledge about how such supplier integration and open innovation practices should be organized and managed is scarce. The purpose of this investigation is therefore to explore how process firms can organize and manage supplier integration and open innovation practices when developing and installing new process technology. By means of a literature review and a case study of two process firms, a lifecycle perspective on procurement is adopted. Our results show that the process firms utilize different interconnected cooperative procurement procedures in different stages of the equipment's lifecycle, in order to enhance integration both in buyer-supplier dyads and among the suppliers in the project network. The contributions of the paper are summarized and illustrated in a developed lifecycle-based procurement model that guides practitioners in organizing and managing supplier integration and open innovation practices.
Oceansense
Authors: Liu Kebin , Yang Zheng , Li Mo , Guo Zhongwen , Guo Ying , Hong Feng , Yang Xiaohui , He Yuan , Feng Yuan , Liu Yunhao
Published: September 2010

In this project, we explore the possibility of deploying networked sensors on the Ocean's surface, to monitor depth and temperature, as well as other valuable environmental parameters. Sea depth monitoring is a critical task to ensure the safe operation of harbors. Traditional schemes largely rely on labor-intensive work and expensive hardware. We present a new solution for measuring the sea depth with Restricted Floating Sensors. To address the problem of node localization on the changeable sea environment, we propose Perpendicular Intersection (PI), a novel mobile-assisted localization scheme. In the OceanSense project, we propose the concept of passive diagnosis as well as the PAD approach which is both lightweight and adaptive to network dynamics. The OceanSense system has been working for over 16 months and provides large amounts of valuable data about the sea.
DNIS
Authors: Saeed Ahmed , Habak Karim , Fouad Mahmoud , Youssef Moustafa
Published: September 2010

Wireless Intelligent Networks Center, Nile University, Smart Village, Egypt Many of today's mobile devices are equipped with multiple network interfaces that can be used to connect to the Internet, including Ethernet, WiFi, 3G, and Bluetooth. However, current operating systems, such as Windows and Linux, typically choose only one of the available network interfaces and assign all the traffic to it, even if more than one is connected to the Internet. This results in an obvious under utilization of the available bandwidth. Different bandwidth aggregation techniques suggested altering different layers of the TCP/IP stack which requires applying modifications on the client's stack and/or the cloud, which cannot be widely deployed easily. In this work, we present DNIS, a networking middleware that achieves bandwidth aggregation using per-TCP connection scheduling on different interfaces in a way that is transparent to both the user and the applications. DNIS is composed of two main components: (1) a parameter estimator that estimates the applications' characteristics and requirements as well as interfaces' properties; (2) a scheduler that uses the estimated parameters to assign different TCP connections to network interfaces. We present an implementation for DNIS for the Windows OS and show its performance for different scheduling algorithms. Our initial results show significant enhancement of the overall device's throughput, up to 54%, increasing resource utilization and enhancing the user's experience.
Real Options in Resource Economics
Authors: Mezey Esther W. , Conrad Jon M.
Published: September 2010

In the real options approach to capital budgeting, plans that allow for flexibility in the design or timing of an investment or economic action are valuable. Real options naturally arise in decisions to develop, extract, or harvest natural resources. We (a) review the existing literature in the economics of forestry, fishery, water, and nonrenewable resources; (b) illustrate the real options approach in resource economics through a series of simple models; and (c) suggest open questions and new areas of application when taking a real options approach to the development and management of natural resources.
What Have We Learned from 20 Years of Stated Preference Research in Less-Developed Countries?
Authors: Whittington Dale
Published: September 2010

Over the past two decades, hundreds of stated preference studies have been conducted in less-developed countries. This article examines what has been learned on the methodological front from stated preference research, and it summarizes the empirical evidence from stated preference studies about household preferences in less-developed countries. The main conclusion is that households' willingness to pay for a wide range of goods and services offered to respondents in stated preference scenarios is low, in both relative and absolute terms and in comparison to the costs of service provision. This article discusses why this finding is important for development professionals. The article also identifies what is missing from the literature on stated preference studies in less-developed countries.
Providing Safe Water: Evidence from Randomized Evaluations
Authors: Ahuja Amrita , Kremer Michael , Zwane Alix Peterson
Published: September 2010

This paper uses a public economics framework to review evidence from randomized trials on domestic water access and quality in developing countries and to assess the case for subsidies. Water treatment can cost-effectively reduce reported diarrhea. However, many consumers have low willingness to pay for cleaner water; few households purchase household water treatment under retail models. Free point-of-collection water treatment systems designed to make water treatment convenient and salient can generate take-up of approximately 60% at a projected cost as low as $20 per year of life saved, comparable to vaccine costs. In contrast, the limited existing evidence suggests that many consumers value better access to water, but it does not yet demonstrate that better access improves health. The randomized impact evaluations reviewed have also generated methodological insights on a range of topics, including (a) the role of survey effects in health data collection, (b) methods to test for sunk-cost effects, (c) divergence in revealed preference and stated preference valuation measures, and (d) parameter estimation for structural policy simulations.
The Benefit-Transfer Challenges
Authors: Boyle Kevin J. , Kuminoff Nicolai V. , Parmeter Christopher F. , Pope Jaren C.
Published: September 2010

Presidential Executive Order 12,866 requires federal agencies to design “cost-effective” regulations and to assess “costs and benefits” of these regulations on the basis of “the best reasonably obtainable scientific, technical, economic, and other information.” Benefit transfers are one economic approach used to estimate these benefits and costs, and the use of existing economic information to predict the effects of new policies is well established. However, advancing the practice of benefit transfers is crucial if economists are to play a role in developing federal policies. We review contributions to the benefit-transfer literature and present a unified conceptual framework to guide the design and evaluation of benefit-transfer guidelines.
Product Differentiation and Quality in Food Markets: Industrial Organization Implications
Authors: Saitone Tina L. , Sexton Richard J.
Published: September 2010

This paper summarizes and evaluates recent research on food product quality and differentiation, both key dimensions of modern food markets. We emphasize the implications for modeling of violation of the product homogeneity and perfect information axioms of perfect competition and focus on issues that are important and/or unique to agriculture. We first review modeling approaches for studying competition in differentiated-agricultural-product markets and then address research in the areas of product quality, labeling, and certification. A unique aspect of agricultural industries is the autonomy that they often have to engage in collective action and self-regulation through producer-controlled marketing organizations. We investigate the role of these organizations in influencing and certifying product quality and in creating product differentiation.
Sustained activation of renal N-methyl-d-aspartate receptors decreases vitamin D synthesis: a possible role for glutamate on the onset of secondary HPT
Authors: Parisi Eva , Bozic Milica , Ibarz Mercé , Panizo Sara , Valcheva Petya , Coll Blai , Fernández Elvira , Valdivielso José M.
Published: September 2010

N-methyl-d-aspartate (NMDA) receptors (NMDAR) are tetrameric amino acid receptors that act as membrane calcium channels. The presence of the receptor has been detected in the principal organs responsible for calcium homeostasis (kidney, bone, and parathyroid gland), pointing to a possible role in mineral metabolism. The aim of this study was to test the effect of NMDAR activation in the kidney and on 1,25(OH)2D3 synthesis. We determined the presence of NMDAR subunits in HK-2 (human kidney cells) cells and proved its functionality. NMDA treatment for 4 days induced a decrease in 1α-hydroxylase levels and 1,25(OH)2D3 synthesis through the activation of the MAPK/ERK pathway in HK-2 cells. In vivo administration of NMDA for 4 days also caused a decrease in blood 1,25(OH)2D3 levels in healthy animals and an increase in blood PTH levels. This increase in PTH induced a decrease in the urinary excretion of calcium and an increase in urinary excretion of phosphorous and sodium as well as in diuresis. Bone turnover markers also increased. Animals with 5/6 nephrectomy showed low levels of renal 1α-hydroxylase as well as high levels of renal glutamate compared with healthy animals. In conclusion, NMDAR activation in the kidney causes a decrease in 1,25(OH)2D3 synthesis, which induces an increase on PTH synthesis and release. In animals with chronic kidney disease, high renal levels of glutamate could be involved in the downregulation of 1α-hydroxylase expression.
HCBPM: An Idea toward a Social Learning Environment for Humanoid Robot
Authors: Alnajjar Fady , Hafiz Abdul Rahman , Murase Kazuyuki
Published: September 2010

To advance robotics toward real-world applications, a growing body of research has focused on the development of control systems for humanoid robots in recent years. Several approaches have been proposed to support the learning stage of such controllers, where the robot can learn new behaviors by observing and/or receiving direct guidance from a human or even another robot. These approaches require dynamic learning and memorization techniques, which the robot can use to reform and update its internal systems continuously while learning new behaviors. Against this background, this study investigates a new approach to the development of an incremental learning and memorization model. This approach was inspired by the principles of neuroscience, and the developed model was named “Hierarchical Constructive Backpropagation with Memory” (HCBPM). The validity of the model was tested by teaching a humanoid robot to recognize a group of objects through natural interaction. The experimental results indicate that the proposed model efficiently enhances real-time machine learning in general and can be used to establish an environment suitable for social learning between the robot and the user in particular.
On the Convergence of Truncated Processes of Multiserver Retrial Queues
Authors: Domenech-Benlloch M. Jose , Gimenez-Guzman Jose Manuel , Pla Vicent , Martinez-Bauset Jorge , Casares-Giner Vicente
Published: September 2010

Retrial queues can only be solved in a closed form in very few and simple cases,
so researchers must resort to approximate models. However, most of the papers that
propose approximate models assume the convergence of the proposed models to their
exact counterparts, without providing a rigorous mathematical proof. In this paper we
demonstrate the convergence of finite truncated models with two reattempt orbits.
Computing the Discrete Compactness of Orthogonal Pseudo‐Polytopes via Their nD‐EVM Representation
Authors: Pérez-Aguila Ricardo
Published: September 2010

This work is devoted to present a methodology for the computation of Discrete Compactness in n‐dimensional orthogonal pseudo‐polytopes. The proposed procedures take in account compactness′ definitions originally presented for the 2D and 3D cases and extend them directly for considering the nD case. There are introduced efficient algorithms for computing discrete compactness which are based on an orthogonal polytopes representation scheme known as the Extreme Vertices Model in the n‐Dimensional Space (nD‐EVM). It will be shown the potential of the application of Discrete Compactness in higher‐dimensional contexts by applying it, through EVM‐based algorithms, in the classification of video sequences, associated to the monitoring of a volcano′s activity, which are expressed as 4D orthogonal polytopes in the space‐color‐time geometry.
Toxicity Profile of the Aqueous Ethanol Root Extract of Corrigiola telephiifolia Pourr. (Caryophyllaceae) in Rodents
Authors: Lakmichi Hind , Bakhtaoui Fatima Zahra , Gadhi Chemseddoha A. , Ezoubeiri Aicha , El Jahiri Younes , El Mansouri Abdellah , Zrara Ibtissam , Loutfi Kenza
Published: September 2010

Corrigiola telephiifolia Pourr. (Caryophyllaceae) is a Moroccan medicinal plant. Despite its popular usage, no study has been published concerning its toxicological profile. The acute toxicity of C. telephiifolia root extract was evaluated by giving it orally to mice at single doses of 5000, 10000, and 14000 mg/kg bodyweight. The extract was also administered at doses of 5, 70, and 2000 mg/kg bodyweight per day to rats for a forty‐day toxicity study. No mortality or signs of toxicity were observed in the acute study. In the forty‐day study in rats, the extract at 5 mg/kg/day showed no toxicological effects in either sex. At 70 mg/kg/day, the treated group differed from the control only by a significant decrease in serum concentrations of sodium and chloride ions (P < .05). At the dose of 2000 mg/kg/day, the extract significantly increased the serum concentrations of creatinine, alkaline phosphatase, gamma‐glutamyltransferase and phosphorus (P < .05) all suggestive of functional nephrotoxicity and hepatotoxicity. The relative bodyweight of both sexes decreased at the dose of 2000 mg/kg/day, with a fast recovery for males. Histological examination did not reveal any treatment‐related effects. In conclusion, Corrigiola extract appears safe at the doses used ethno‐medicinally. Much higher doses pose toxicological risks.