bluuebunny/crossref_metadata_2025 huggingface dataset:
Some 2-nitromethyl-, 2,6-bis(nitromethyl)-, 2-cyano-, and 2,6-dicyano-substituted derivatives of polyalkylated 3,5-dicyano-1,4-dihydropyridines
Authors: Kurfürst Antonín , Schwarz Marián
Published: May 2010

Nitration of polyalkyated 3,5-dicyano-1,4-dihydropyridines Ia-Id to the first and second degrees has been studied leading to compounds II and III, and conversion of nitromethyl groups of these compounds into nitrile groups with formation of tricyano derivatives IV and tetracyano derivatives V has been followed. Also given is the fragmentation of the synthesized compounds II-V by an electron impact in mass spectrometer and further spectral characteristics.
Reactions of N-substituted 2-aminopyridines with chloroacetyl chloride; Formation of a new series of heterocyclic betaines: 1-Substituted 4-chloromethyl-2-oxopyrido[1,2-a]pyrimidin-5-ium-3-olates
Authors: Hulinská Hana , Buděšínský Miloš , Holubek Jiří , Matoušová Oluše , Frycová Hana , Protiva Miroslav
Published: May 2010

N-(2-Pyridyl)-2-chloroacetamide reacted with 1-methylpiperazine and gave the expected compound III. Attempts at preparing the N-substituted N-(2-pyridyl)-2-chloroacetamides by reactions of N-substituted 2-aminopyridines with chloroacetyl chloride in benzene in the presence of N,N-dimethylacetamide were negative and took an unexpected course. 2-Anilinopyridine and 2-(cyclohexylamino)pyridine afforded compounds which were identified by 1H and 13C NMR spectra as the heterocyclic betaines IVa and IVb. 2-(1-Butylamino)pyridine, 2-(benzylamino)pyridine and 2-(2-phenylethylamino)pyridine gave similarly compounds IVc-IVe. The chloromethyl compounds IVa-IVe underwent normal substitution reactions with 1-methylpiperazine and gave the methylpiperazino compounds Va-Ve. Attempts to reduce the betaines with sodium borohydride in aqueous ethanol proceeded in one case as the hydrogenolytic displacement of the chlorine atom with hydrogen (product VIa), in another case as ethanolysis (product VIIb). Formation of VIb by treatment of IVb with hydrogen bromide in boiling acetic acid is probably the result of a disproportionation reaction. Compound III (dimaleate VÚFB-17 103) was practically equipotent with pirenzepine (I) as an anti-ulcer agent in the test of indomethacine-induced gastric lesions in rats but was much weaker in tests for antocholinergic and antisecretory activity.
Calculation of energies of excited states with MNDO CI method
Authors: Ertl Peter
Published: May 2010

The energies of the lowest singlet excited states of eighteen molecules have been calculated by the MNDO half-electron method with configuration interaction. The method overall overestimates the stability of excited states, but the actual values depend on the character of the particular chromophore. The best agreement with experiment was obtained for the conjugated systems.
Extension of a lattice model of electrolytes to a ternary system of a salt and two solvents. The system CH3OH-H2O-LiCl
Authors: Horsák Ivan
Published: May 2010

A lattice model proposed to describe the thermodynamic properties of binary electrolyte solutions over the whole concentration range has been extended to ternary systems involving two solvents. The relationships derived for the excess Gibbs energy and the activity coefficients of all the components have been tested with published experimental data on vapour pressures of methanol and water in the system CH3OH-H2O-LiCl at 60 °C. Examination of the ability of the model to predict the behaviour of the ternary system on the basis of binary data has shown that the expression for the excess Gibbs energy must be extended to include a ternary contribution.
Structural and catalytic properties of MoO3-NiO mixed oxides system
Authors: Said Abd El Aziz A. , Hassan Ehsan A. , El-Awad Ahmed M. , Abd El-Salaam Khalf-Alla M.
Published: May 2010

The unsupported MoO3-NiO catalysts were investigated. The addition process of NiO was followed by electrical conductivity measurements, IR, XRD, surface area and finally catalytic activity measurements. The conductivity measurements revealed an increase in σ values when 2-propanol vapour was admitted in the gas feed. IR and XRD analysis detected a solid state reaction at about 500 °C and its maximum was shown around 70 mole % Ni2+ where NiMoO4 lattice diffraction type was detected. Parallel with these measurements, the catalytic activity was determined for the catalysts calcined at 500 °C using the decomposition of 2-propanol. The conversion and the selectivity increased as Ni2+ was added to a concentration of 70 mole % Ni2+ ions. The results were discussed in respect to the creation of holes associated to Ni2+ addition.
Retention of some heterocyclic amines on mixed stationary phases containing nickel(II) Schiff base chelates
Authors: Masłowska Joanna , Bazylak Grzegorz
Published: May 2010

Stationary phases composed of squalane and some nickel(II)-β-keto amine complexes were prepared and used for the separation of complex mixtures of pyridines. The resolution achieved on short classical columns was comparable with that obtained on capillary columns.
The polarographic and voltammetric determination of semitrypane blue
Authors: Barek Jiří , Ghosh Ashutosh , Zima Jiří
Published: May 2010

The polarographic reduction of the azodye semitrypane blue has been studied, a mechanism has been proposed and optimal conditions have been found for the determination of this substance by TAST polarography (to 2.10-6 mol l-1) and differential pulse polarography (to 1.10-7 mol l-1) at a classical dropping mercury electrode and by fast scan differential pulse voltammetry (to 1.10-8 mol l-1) and linear scan voltammetry (to 1.10-8 mol l-1) at a hanging mercury drop electrode. The detection limit was decreased to 1.10-9 mol l-1 for fast scan differential pulse voltammetry and 1.10-10 mol l-1 for linear scan voltammetry by using adsorptive accumulation of the determined substance at the hanging mercury drop electrode.
Reduction of oxygen to peroxide in a trickle electrode
Authors: Špalek Otomar , Balogh Karel
Published: May 2010

The effects of the electrode material particle size, electrode thickness, diaphragm properties and gas and electrolyte flow rates on the pressure loss and liquid holdup in the electrode and on the current efficiency of peroxide formation by oxygen reduction were studied in a trickle electrode. The results are discussed using trickle-bed electrode calculations.
The photochemical stabilization of block copolymer micelles
Authors: Procházka Karel , Kupková Kateřina , Burda Jaroslav , Tuzar Zdeněk , Bednář Bohumil
Published: May 2010

Conditions of the polymolecular micellization of a linear three-block copolymer-polystyrene-block-polybutadiene-block-polystyrene in a binary solvent tetrahydrofuran-ethanol were determined. Photochemical stabilization of micelles by the crosslinking of polybutadiene chains in the cores induced by intense UV radiation was carried out in a tetrahydrofuran-ethanol mixture (34.5 vol. %), in which compact micelles with the polybutadiene core are formed and, at 25 °C, the micellization equilibrium is markedly shifted in favour of micelles containing a large number of associated copolymer chains. The kinetics of crosslinking of the micellar cores and the behaviour of stabilized micelles in solution were investigated.
QELSS diffusion data for moderately broad molar mass distribution polymer samples compared with data from classical gradient techniques
Authors: Porsch Bedřich , King Simon , Sundelöf Lars-Olof
Published: May 2010

The differences between the QELSS and classical diffusion coefficient of a polydisperse polymer resulting from distinct definitions of experimentally accessible average values are calculated for two assumed specific forms of molar mass distributions. Predicted deviations are compared with the experiment using NBS 706 standard polystyrene. QELSS Dz of this sample relates within 2-4% to the classical diffusion coefficient, if the Schulz-Zimm molar mass distribution is assumed to be valid. In general, differences between the height-area and QELSS diffusion coefficient of about 20% may be found for Mw/Mn ~ 2, and this value may increase above 35%, if strongly tailing molar mass distribution pertains to the sample.
Sesquiterpene lactones from Venidium hirsutum BEROL. species
Authors: Buděšínský Miloš , Grabarczyk Halina , Daniewski Włodzimierz M. , Wawrzuń Andrzej , Gulumka Maria , Šaman David , Drożdż Bohdan , Holub Miroslav
Published: May 2010

Nine sesquiterpene lactones were identified in the species Venidium hirsutum BEROL. Five of them (I-III, VII and IX) were hitherto undescribed and their structure was determined.
Conformation of ring A in triterpenoid ketones. Carbon-13 chemical shifts and spin-lattice relaxation times of lupane and 18α-oleanane derivatives
Authors: Buděšínský Miloš , Klinot Jiří
Published: May 2010

13C NMR spectra of sixteen lupane and 19β,28-epoxy-18α-oleanane triterpenoids I-XVI were measured and a complete structural assignment of chemical shifts was made. For most compounds also the carbon spin-lattice relaxation times T1 were obtained. Characteristic differences in chemical shifts of some carbon atom signals were found between 2α-methyl-3-oxo and 2α-methyl-1-oxo derivatives II, V and VIII with chair conformation of the ring A on the one hand and their 2β-isomers III, VI and IX (boat form) on the other. Using these 2-methyl ketones as models, the chair-boat population in allobetulone (I), 3-oxo-28-lupanenitrile (IV) and 1-oxo derivative VII was determined. The results agree well with the data obtained by other physical methods.
Potential antidepressants: 10-Amino-2-chloro-10,11-dihydrodibenzo[b,f]thiepins
Authors: Valenta Vladimír , Vlková Marie , Holubek Jiří , Metyšová Jiřina , Protiva Miroslav
Published: May 2010

Reduction of N-(2-chloro-10,11-dihydrodibenzo[b,f]thiepin-10-yl)formamide with lithium aluminium hydride resulted in the methylamino compound IV. The dimethylamino compound V was obtained by methylation of 10-amino-2-chloro-10,11-dihydrodibenzo[b,f]thiepin with formic acid and aqueous formaldehyde. Substitution reactions of 2,10-dichloro-10,11-dihydrodibenzo[b,f]thiepin with a series of primary and secondary amines afforded the title compounds VI to XXVIII. The bases were transformed to salts and pharmacologically tested. Only the pyrrolidino compound IX (hydrogen succinate VÚFB-15 551) showed a clear pharmacological profile of a potential antidepressant.
Selectivity changes of acetone transformation over ZSM-5 zeolites with different acido-basic properties
Authors: Čejka Jiří , Kubelková Ludmila , Jírů Pavel
Published: May 2010

Acetone transformation catalyzed by HZSM-5 and NaZSM-5 zeolites and by zeolites modified with basic oxides was studied in an integral reactor at a temperature of 350 °C. Modification of acido-basic properties of ZSM-5 zeolites resulted both in the total conversion changes and in the essential changes in the product composition. Isobutene was found to be the main product over HZSM-5 zeolites exhibiting low activity, while aromatics prevailed when high conversion level was attained. Classical condensation of acetone yielding mesityloxide and phorones was observed over NaZSM-5 zeolites impregnated with CaO and ZnO.
Isolation and partial characterization of a peptidase with trypsin-like activity from bovine adenohypophysis
Authors: Dash Tsezengijn , Barth Tomislav , Slaninová Jiřina , Barthová Jana , Mašková Hana P. , Hauzer Karel , Kasafírek Evžen
Published: May 2010

A reproducible method has been developed for the isolation of the adenohypophyseal enzyme with a trypsin-like activity. The enzyme is able to hydrolyze Nα-benzoyl-L-arginine-p-nitroanilide, a fluorogenic substrate CBzl-Arg-Arg-β-naphthyl amide and some peptides with one or two accumulated basic amino acids in the chain. The optimum pH for hydrolysis of the chromogenic substrate was within the range 6.0-7.0 (Km = 0.66 mmol l-1), in the case of the fluorogenic substrate the range was between 7.0 and 7.5 (Km = 1.2 μmol l-1). The enzyme is activated by cysteine and dithiothreitol and inhibited by SH-poisons. The molecular weight of the enzyme, determined by means of two independent methods, was approximately 25 kDA.
Application of a model of regular solutions to ionic melts
Authors: Leško Juraj , Kalousek Jaroslav , Kupčák Jaroslav , Bochňák Radim
Published: May 2010

The paper presents a review of applications of the model of regular solutions to ionic melts with regard to metallurgical slags. Various theoretical approaches to systems with a single common ion are discussed. A survey of experimentally determined interaction coefficients for basic metallurgical systems is given. Data for the model of regular solutions for arbitrary numbers of cations and anions are briefly discussed.
Insect juvenile hormones and their bioanalogues
Authors: Wimmer Zdeněk , Romaňuk Miroslav
Published: May 2010

This survey supplements and up-dates review articles of other authors published in the field of substances affecting the development of the insect, juvenoids. Attention has been paid primarily to such structures as deserved more detailed investigation in the given field owing to their biological properties, further to less known structures and facts, and lastly to the most recent information from literature, mainly paying attention to the present trend in searching for structural types of substances affecting insect development. The synthetic juvenoids discussed are divided into chapters, on the basis of the skeleton of the molecule, on aliphatic juvenoids, juvenoids with one aromatic ring in the molecule and finally juvenoids with two and more cycles (aromatic as well as non-aromatic) in the molecule. Certain attention has also been paid to optically active juvenoids. Finally the role is mentioned of complex hormonogen compounds, juvenogens, in the protection of cultured plants against economically important insect pests.
Analysis of chemical reaction systems by means of network thermodynamics
Authors: Horno José , González-Fernández Carlos F.
Published: May 2010

The simple network thermodynamics approach is applied to chemical reaction systems, whereby chemical reactions can be studied avoiding complex mathematical treatment. Steady state reaction rates are obtained for two chemical reaction systems, viz. the decomposition of ozone and the reaction of hydrogen with bromine. The rate equations so obtained agree with those derived from the chemical kinetics concept.
Energetic efficiency of two impellers on the same shaft in a cylindrical baffled vessel of high height/diameter ratio
Authors: Fořt Ivan , Hájek Jiří , Machoň Václav
Published: May 2010

The paper deals with the experimental study of the indicating particle circulation and the impeller power input in a liquid mechanically agitated with two high-speed impellers (combination of the standard turbine impeller and the six inclined (at 45°) plane blades impeller) on the same shaft in a slender vessel (its height is equal double of the vessel diameter) equipped with four radial baffles at its walls under the turbulent regime of agitated charge flow. By the visual method of the indicating particle it is examined its circulation in the lower part of the system pumping effect of the lower impeller), its circulation in the upper part of the system (pumping effect of the upper impeller), and the exchangeable circulation between the upper and lower part of the system and vice versa. The impeller power input is ascertained from the measured current electricity in the anchor of the direct current driving motor. It follows from the calculated energetic efficiency (the ratio of the cube of the sum of the impeller flow rate numbers and the sum of the impeller power numbers) of the investigated combinations of impellers that the highest value of this quantity is exhibited for two standard turbine impellers on the same shaft and for a combination of the lower standard turbine impeller and the upper impeller with inclined plane blades pumping upwards; slightly less value of the impeller energetic efficiency appears for the combination of two impellers with six inclined plane blades, the upper one pumps liquid upwards and the lower one downwards. For all the configurations the vertical distance of impellers on the same shaft has to be longer than the vessel diameter.
Partition mechanism of adsorption and the absence of displacement phenomena in the zonal analytical chromatography of proteins on bead 2-hydroxy-3-phenoxypropyl-cellulose
Authors: Gemeiner Peter , Hrabárová Eva , Zacharová Magdaléna , Breier Albert , Beneš Milan J.
Published: May 2010

Hydrophobization of bead cellulose is described, carried out by its alkylation with 1,2-epoxy-3-phenoxypropane under the conditions of acid (perchloric acid, borontrifluoride diethyl etherate) and basic (sodium hydroxide) catalysis. Reaction conditions (temperature, reaction time, molar ratio of reactants) have been determined, allowing the hydrophobization of bead cellulose to be carried out to the largest possible extent while maintaining its spherical shape. The nonstoichiometric mechanism suggested for the adsorption of amphiphilic adsorptives on bead 2-hydroxy-3-phenoxypropyl-cellulose (HPP-C) was checked by means of adsorption of six proteins. It was found that the surface of the hydrophobic segment of the adsorbent must be sufficiently large to be able to come in touch with the hydrophobic region of the protein through its multiple residues. In such cases the partitioning of the protein between the hydrophobic segment present as a liquid-like film and the surrounding solution becomes the predominant step of the adsorption. This adsorption mechanism is also reflected in zonal chromatography on bead HPP-C, as no displacement phenomena could be observed in any of the six proteins used. Retention of these proteins has been affected to a decisive extent by the degree of hydrophobization of HPP-C.
119Sn, 13C and 1H NMR studies of aryloxy- and arylthio(1-butyl)stannanes
Authors: Lyčka Antonín , Holeček Jaroslav , Handlíř Karel
Published: May 2010

Two series of compounds have been prepared and studied by means of 119Sn, 13C, and 1H NMR spectroscopy, viz. aryloxy- and N-heteroaryloxytris(1-butyl)stannanes and their thio analogues Bu3SnER, and diaryloxy- and di(N-heteroaryloxy)bis(1-butyl)stannanes and their thio analogues Bu2Sn(ER)2, where E means oxygen or sulfur, Bu is 1-butyl, R = phenyl, 1-naphthyl, or 8-quinolyl. On the basis of mutual comparison of NMR spectral parameters of both series of organotin compounds and their comparison with NMR spectral parameters of analogous, purely organic compounds CH3ER it is possible to discuss the consequences of the presence of tin atoms in the organotin substituents and of nitrogen heteroatoms in the aromatic systems, and the therefrom following structure of the organotin compounds studied.
Preparation of unsymmetrically substituted Stenhouse salts
Authors: Šafář Peter , Kováč Jaroslav
Published: May 2010

Unsymmetrically substituted Stenhouse salts IVa-IVj (iminium salts of 1-phenylmethylamino-5-(4-X-phenylamino)-2-hydroxy-2,4-pentadienal) arise by reaction of N-2-furfurylidene-N-phenylmethyliminium perchlorate (V) with substituted anilines. Primary and secondary aliphatic amines do not react in this way. Unsymmetrically substituted Stenhouse salts are also formed from iminium salt of 1,5-di(phenylmethylamino)-2-acetoxy-2,4-pentadienal (IV) by nucleophilic substitution with aromatic and aliphatic amines.
Laser optoacoustic detection of trace concentration levels of ethylene, vinylchloride, and styrene in the atmosphere
Authors: Steiner Vojtěch , Engst Pavel , Zelinger Zdeněk , Horák Milan
Published: May 2010

The optoacoustic analyzer with a tunable CO2 laser source employed in the present work permits a selective determination of ethylene in trace concentrations higher than 5 ppb (=detection limit for the 10P(14) emission line of the CO2 laser, ν = 949.5 cm-1) and of vinylchloride higher than 42 ppb (= detection limit for the 10P(22) CO2 laser line, ν= 942.4 cm-1). this method covers for both compounds the concentration range corresponding to the hygienic standard. It can be also used for the determination of styrene vapour with concentrations higher than 1.5 ppm.
The FIA determination of lead with 4-(2-pyridylazo)resorcinol after preconcentration on a microcolumn of a chelating sorbent
Authors: Kubáň Vlastimil , Bulawa Radim
Published: May 2010

Lead can be determined conveniently by the classical or reversed FIA technique using photometric detection with 4-(2-pyridylazo)resorcinol ( cPAR = 0.1 mol l-1) in 0.1M borate buffer (λ 518 nm). For injected volumes of 50 μl, the lead concentrations can lie in the regions of 1-20 and 0.4=18 μmol l-1, respectively. The selectivity of determination can be increased one to two orders of magnitude by masking with a mixture of EDTA ( 5 μmol l-1), tartaric acid (20 μmol 1-1) and KCN (2 mmol 1-1). When combining the analysis with preconcentration on a 3 x 30 mm microcolumn of Spheron Oxin 1 000 chelating sorbent from 0.01M ammonium acetate solutions at pH 6.5 followed by elution with 0.1M-HCl, lead can be determined in concentrations of 0.1–1.2, 0.02–0.85 or 0.01–0.60 μmol 1-1 for sample volumes of 5, 10 or 20 ml, respectively. The repeatability of determination for ten independent measurements on 5, 10 and 20 ml sample volumes at cPb = 0.2, 0.05 μmol 1-1, respectively, was better than 4.7, 2.8 and 6.2%, respectively. The methodi of preconcentration on a chelating sorbent was applied to the analysis of clean industrial wastewaters. The relative deviation of the lead concentration did not exceed 6.5% in comparison with data obtained by AAS.
Affinity chromatography of arginase with continuous detection of enzyme using urease membrane electrode
Authors: Macholán Lumír , Hlavatá Bohdana
Published: May 2010

A rapid method is described of potentiometric measurement of liver arginase during its purification on a column of affinity adsorbent prepared by the derivatization of Spheron E-1000. The detection of the enzyme in the flow-through system is effected by an ammonia electrode coated by the reaction layer of glutaraldehyde-crosslinked urease on a polyamide mesh. The method is time- and urease-saving and permits arginase to be obtained for analytical purposes purified 212 times from a liver extract in a 68% yield. By combining the membrane made of crosslinked arginase and urease on a polyamide mesh with a pNH3 electrode we developed a two-enzyme sequence electrode sensitive to L-arginine (10-3 -10-4 mol l-1) showing a response time of 1-3 min and a stability of about 3 weeks.
Elimination of dead-volume contributions to moments of chromatographic peaks
Authors: Davidová Helena , Schneider Petr
Published: May 2010

two methods for correction of moments of peaks from packed columns were applied to experimental responses of columns packed with porous γ-aluminia in the shape of Rasching rings: 1. substraction of moments for columns of two lengths and 2. application of dead volume corrections obtained by independent measurements. It appears that both methods give identical results. An advantage of the second methods lies in increased accuracy and decreased amount of necessary measurements.
Kinetics of 1-butanol, di-(1-butyl) ether and 1-butene reactions on aluminas partially deactivated by sodium
Authors: Krampera František , Beránek Ludvík
Published: May 2010

The initial rates of six reactions taking place in 1-butanol dehydration at 260 °C in vapour phase were measured on aluminia samples differing in sodium content. The reactants were 1-butanol, di-(1-butyl) ether and 1-butene, resp. The parameters of the best fitting rate equation for each reaction were evaluated. The reaction rates as well as the rate constants and adsorption coefficients of the individual reactions show different sensitivity to datalyst acidity. Therefore, the selectivity of product formation can be influenced by sodium content of the catalyst. The selectivities (with the exception of 1-butene izomerization) strongly depend also on the partial pressure of the starting reactants. Thus, these two factors can be used to control the selectivity for preparative purposes. The results of this paper clearly demonstrate the nonseparability of the deactivation kinetics in 1-butanol dehydration on sodium poisoned aluminas.
The information-theoretical and system basis of quantitative analysis
Authors: Eckschlager Karel
Published: May 2010

It is shown that the individual subsystems of a stochastic analytical system affect the a posteriori uncertainty and thereby, the information gain of the analytical result. The effects of sampling, separation procedures and calibration on the information gain of quantitative analysis, expressed in terms of the extended divergence measure, are discussed, and rules that can be utilized in the optimization of analytical procedures are given.
Mass transfer rate from gas bubbles into liquid in presence of solid particles with strong adsorbing properties
Authors: Kratochvíl Jan , Kaštánek František
Published: May 2010

The presence of small particles with adsorbing activity (carbon soot, active carbon etc.) in the bubble bed augments the gas-liquid mass transfer coefficient kLa about approximately 20% in comparison with pure liquid. This fact can be explained by penetrating and disturbance effect of particles into the boundary layer of liquid near the interface. This activity is however reduced to small concentrations of particles (0.07% mass in the case of carbon soot, 0.5%-1.0% mass for active carbon particles). Addition of small amount of particles with adsorbing activity to the liquids containing superficial active agents (tensides) can partially overcome the negative effect of tensides on kLa value. The positive effect of particles of active carbon on kLa in bubble beds is less pronounced than that published for the case of mechanically agitated vessels.
Continuous wave CO2 laser driven oxidation of 2-butene and 2-octafluorobutene
Authors: Pola Josef , Vítek Josef
Published: May 2010

CW CO2 laser induced reactions of 2-butene and 2-octafluorobutene with molecular ground state 3O2 oxygen in the presence of sulfur hexafluoride afford products that can be rationalized by means of the earlier proposed mechanism involving transient dioxetane and its cleavage into carbonyl compounds.
Electropolymerization of aniline and some of its derivatives
Authors: Dempírová Ludmila , Adamcová Zdena
Published: May 2010

The effect of substitution on the aromatic ring of aniline and in its amino group on the potential of polymerization in aqueous medium and on the charge passed during polymerization was studied. The formation of polymer films on the working electrode and their electrochromic changes were also examined. From the electro-oxidation of aniline, the number of reversible and irreversible steps, the number of electrons exchanged and the type of oxidation mechanism were found. Thickness of a single layer of polyaniline, formed by cycling the potential in the range –0.2 V, +1.4 V(vs SCE) at a polarization rate of 5 mV/s, was estimated considering the oxidation mechanism of aniline. The electrochemical behaviour of aniline in anhydrous acetonitrile medium was also studied. It was found by blocking the m- and p-positions in aniline by a methyl substituent that polymerization of aniline occurs through the p-position. The porosity of the polymer films was estimated from the diffusion coefficient values for 1.10-3M K3[Fe(CN)]6 in 0.1M-KCl calculated from the Randles-Sevcik equation for measurements on Pt electrodes with a polymer film, compared with the tabulated values for a bare Pt electrode.
Configuration on the C=N double bond of monosubstituted amidines and amidoximes
Authors: Tinant Bernard , Dupont-Fenfau Janine , Declercq Jean-Paul , Podlaha Jaroslav , Exner Otto
Published: May 2010

Configuration on the C=N double bond of amidines and amidoximes is controlled by steric effects on the second nitrogen atom but there is a difference in the case of N’-monosubstituted derivatives: amidines prefer E configuration (conformation around the C-N bond sp) and amidoximes Z configuration (conformation ap). This was confirmed by the X-ray structures of two analogous model compounds N,N’-dimethyl-4-nitrobenzamidine (monoclinic, P21c, a = 10.855(3), b = 11.043(3), c = 8.593(3) Å, β = 105.69(2)°, V = 991.8(5) Å3, Z = 4, Dx = 1.29 g cm-3, CuKα, λ = 1.5418 Å, μ = 7.91 cm-1, F(000) = 408, T = 291 K, R = 0.065 for 1 265 observed reflections) and N’-methyl-4-nitrobenzamidoxime (monoclinic, P21/a, a = 6.699(2), b = 24.178(9), c = 6.075(2) Å, β = 106.20(3)°, V = 944.9(6) Å3, Z = 4, Dx = 1.37 g cm-3, CuKα, λ = 1.5418 Å, μ =9.22 cm-1, F(000) = 408, T = 291 K, R = 0.079 for 1 278 observed reflections).
Synthesis and in vitro antimetabolic evaluation of some steroidal thiazoles
Authors: Drašar Pavel , Pouzar Vladimír , Černý Ivan , Pettit George R. , Havel Miroslav
Published: May 2010

Steroidal thiazoles VI-XII have been synthesized. The starting bromoketones XVII and XX were prepared by bromination of pregnan-20-ones in position 21 with copper(II) bromide, and used for synthesis of the thiazole derivatives employing the Hantzch reaction. Preliminary biological evaluation of thiazoles I-XII against the P388 lymphocytic leukemia cell line showed growth inhibition values of ED50 2.9 and 7 μg/ml for thiazoles II and VII, respectively.
Syntheis of brassino steroids with a five carbon atom ester functionality in position 17
Authors: Kohout Ladislav
Published: May 2010

Androstane analogues of brassinolide with a five carbon atom ester functionality in position 17 have been prepared. 2α,3α-Dihydroxy-17β-(3-methylbutyryloxy)-7-oxa-B-homo-5α-androstan-6-one (XVIII) exhibited a suprisingly high brassinolide activity.
Kinetics analysis of the decay of phenylhydrazonopropanedinitrile addition products with thiols in aqueous solutions
Authors: Antalík Marián , Šturdík Ernest , Podhradský Dušan , Poleková Ingrid , Drobnica Ľudovít
Published: May 2010

The reactions of phenylhydrazonopropanedinitriles with thiols are reversible and with increasing pH-values of aqueous solutions the equilibrium is shifted them to the side of the reactants. A mechanism of the decay of corresponding addition products was proposed and the kinetic description based on this mechanism is in good agreement with the obtained experimental data. From the viewpoint of the decay, the pH-dependent dissociation of the proton of the imino group formed by addition of thiol to the nitrile carbon atom plays a decisive role. The obtained knowledge is useful with respect to the use of phenylhydrazonopropanedinitriles as affinants for selective and reversible sorption of low-molecular thiols and thiol-proteins in affinity chromatography as well as for the study of the mechanism of the effect of these substances in oxidative and photosynthetic phosphorylation and biological systems in general.
Design of a protocol for large-scale epidemiological studies in individual sports: the Swedish Athletics injury study
Authors: Jacobsson Jenny , Timpka Toomas , Ekberg Joakim , Kowalski Jan , Nilsson Sverker , Renström Per
Published: May 2010

Background

Epidemiological studies have mainly been performed on team sports. The authors set out to develop a protocol for large-scale epidemiological studies of injuries among elite athletics athletes.

Methods

An argument-based method for investigation of complex design problems was used to structure the collection and analysis of data. Specification of the protocol was preceded by an examination of requirements on injury surveillance in individual sports and iterated drafting of protocol specifications, and followed by formative evaluations.

Results

The requirements analysis shows that the central demand on the protocol is to allow for detailed epidemiological analyses of overuse injuries, which subsequently requires regular collection of self-reported data from athletes. The resulting study protocol is centred on a web-based weekly athlete e-diary enabling continual collection of individual-level data on exposure and injuries. To be able to interpret the self-reported data on injury events, collection of a wide range of personal baseline data from the athlete, including a psychological profile, is included in the protocol.

Conclusions

The resulting protocol can be employed in intervention programmes that can prevent suffering among both adult elite and youth talent athletes who have made considerable life investments in their sport.
Differential effects of xanthine oxidase inhibition and exercise on albumin concentration in rat tissues
Authors: Veskoukis Aristidis S. , Kyparos Antonios , Stagos Dimitrios , Kouretas Dimitrios
Published: May 2010

Albumin is a protein present in almost all kinds of mammalian cells. It has binding sites for several molecules, and possesses antioxidant and other important properties. The aim of this study was to examine the effects of 2 different oxidative stress stimuli — exercise and allopurinol administration — and their combination on albumin concentration in several rat tissues. Samples of soleus, extensor digitorum longus (EDL), and gastrocnemius muscles, and the liver and heart were collected before, immediately after, and 5 h after exercise, and collected at the respective time points after allopurinol administration. Albumin dimmers, markers of oxidative stress, were also assessed in EDL muscle. Albumin concentration increased in the skeletal muscles examined, whereas it decreased in the heart and remained unaffected in the liver after exercise. Allopurinol alone did not affect albumin concentration in any of the tissues. Albumin concentration increased in soleus and EDL muscles, decreased in gastrocnemius muscle and the liver, and remained unaffected in the heart after exercise and allopurinol combination. Albumin dimmers also increased postexercise in EDL muscle. Our findings suggest that the increase in albumin concentration in skeletal muscles may be an antioxidant mechanism response, but may depend on the type of oxidative stress and be stimulation- and tissue-specific.
The effect of acute fish-oil supplementation on endothelial function and arterial stiffness following a high-fat meal
Authors: Fahs Christopher A. , Yan Huimin , Ranadive Sushant , Rossow Lindy M. , Agiovlasitis Stamatis , Wilund Kenneth R. , Fernhall Bo
Published: May 2010

This study examined whether a commercially available fish-oil supplement offers protection from the acute effects of a high-fat meal (HFM) on endothelial function and arterial stiffness. An HFM causes acute impairments in endothelial function, whereas the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have a variety of cardioprotective effects. However, little is known about the efficacy of moderate fish-oil supplementation on the endothelial dysfunction induced by an HFM. Endothelial function (brachial artery flow-mediated dilation (FMD)), forearm blood flow (FBF), total hyperemia, central and peripheral blood pressure, and central artery stiffness were assessed in 20 healthy men (n = 10) and women (n = 10) at rest and 4 h after an HFM supplemented with either placebo or ∼1 g EPA and DHA. Brachial artery FMD normalized for shear rate was significantly impaired (p = 0.033) following the HFM with placebo but remained unchanged compared with baseline following the HFM with the fish-oil supplement (p = 0.039; condition × time interaction). Resting FBF (p = 0.020) and total hyperemia (p = 0.014) were elevated following the HFM. All other vascular and hemodynamic measurements were unchanged in both trials. Commercially available fish-oil supplements taken with an HFM appear to preserve endothelial function following an HFM.
Effects of high-density lipoprotein on endothelium-dependent vasorelaxation
Authors: McAllister Richard M. , Morris David M. , Weimer Cory M. , Laughlin M. Harold
Published: May 2010

Studies using cultured endothelial cells have shown that high-density lipoprotein (HDL) positively modulates endothelial nitric oxide synthase (eNOS). The purpose of this study was to test the hypotheses that positive modulation of eNOS by HDL occurs in whole vessels and that it augments endothelium-dependent vasorelaxation. To test these hypotheses, brachial arteries were obtained from swine. Endothelium-dependent and endothelium-independent vasorelaxation were determined in vitro to assess the effects of acute administration of HDL (50 μg·mL–1; n = 8) and chronic exposure to relatively high HDL concentration on vascular function (low HDL, 0.89 ± 0.02 mmol·L–1, n = 4; high HDL, 1.16 ± 0.05 mmol·L–1, n = 4; p < 0.005). Acute administration of HDL did not augment maximal endothelium-dependent vasorelaxation to bradykinin (BK) (no HDL, 82.6% ± 2.2%; HDL, 76.7% ± 3.5%; not significant (ns)). Similarly, maximal relaxation to BK was not enhanced by chronic exposure to high HDL concentrations. NO synthase (NOS) activity was also similar between groups (low HDL, 129.0 ± 19.2 counts·h–1·μg–1 protein; high HDL, 113.9 ± 47.1 counts·h–1·μg–1; ns). Consistent with NOS activity, the extent of eNOS phosphorylation at several sites was similar between low HDL and high HDL. Both apolipoprotein A-I (ApoA-I) and scavenger receptor class B type I (SR-BI) were associated with eNOS. Similar to cultured cell studies, this study demonstrates that both ApoA-I and SR-BI associate with eNOS in the vascular wall. Binding of ApoA-I and SR-BI to eNOS does not, however, result in modulation of either NO formation or endothelial function.
On-ice sweat rate, voluntary fluid intake, and sodium balance during practice in male junior ice hockey players drinking water or a carbohydrate–electrolyte solution
Authors: Palmer Matthew S. , Logan Heather M. , Spriet Lawrence L.
Published: May 2010

This study evaluated the repeatability of hydration and sweat measurements taken during on-ice hockey practices with players drinking only water, and determined whether having only a carbohydrate–electrolyte solution (CES) to drink during practices decreased fluid intake or affected other hydration and (or) sweat measures. All testing was conducted on elite players of an Ontario Hockey League team (±SE; mean age, 17.6 ± 0.3 years; mean height, 182.9 ± 1.4 cm; mean body mass, 83.0 ± 1.7 kg). Players were studied 3 times over the course of 6 weekly on-ice practices (±SE; mean playing time, 1.58 ± 0.07 h; mean temperature, 11.4 ± 0.8 °C; mean relative humidity, 52% ± 3%). There was strong repeatability of the measured hydration and sweat parameters between 2 similar on-ice practices when players drank only water. Limiting the players to drinking only a CES (as opposed to water) did not decrease fluid intake during practice (±SE; mean CES intake, 0.72 ± 0.07 L·h–1 vs. mean water intake, 0.82 ± 0.08 L·h–1) or affect sweat rate (1.5 ± 0.1 L·h–1 vs. 1.5 ± 0.1 L·h–1), sweat sodium concentration (72.4 ± 5.6 mmol·L–1 vs. 73.0 ± 4.4 mmol·L–1), or percent body mass loss (1.1% ± 0.2% vs. 0.9% ± 0.2%). Drinking a CES also improved sodium balance (–2.1 ± 0.2 g·h–1 vs. –2.6 ± 0.3 g·h–1) and provided the players with a significant carbohydrate (43 ± 4 g·h–1 vs. 0 ± 0 g·h–1) during practice. In summary, a single field sweat test during similar on-ice hockey practices in male junior hockey players is sufficient to evaluate fluid and electrolyte balance. Also, a CES does not affect voluntary fluid intake during practice, compared with water, in these players. The CES provided some salt to offset the salt lost in sweat, and carbohydrate, which may help maintain physical and mental performance in the later stages of practice.
Environmental evaluation of Turkey’s transboundary rivers' hydropower systems
Authors: Berkun Mehmet
Published: May 2010

The Southeastern Anatolia Project (GAP), encompassing 27 dams and 19 hydroelectric power plants, is a large-scale water management program aiming at an increase in domestic electricity production and the development of vast irrigation schemes for agriculture. In spite of numerous benefits experienced in the area, there is also a multitude of impacts observed on the environment. The Coruh River is the longest river of the East Black Sea region and is of high economic importance to Turkey because of its largely exploitable hydropower potential. The Coruh project consists of 27 planned dams and hydroelectric power plants. The planned dams have the potential to cause serious environmental effects in upstream Turkey and downstream Georgia. Equitable, rational, and optimal utilization of transboundary water resources can be achieved through a scientific study, which will determine the true water needs of each riparian country. A precise assessment is needed of the economic, ecological, and social problems on the basis of the environmental impact and cumulative effect assessment reports.
Analysis of work trip timing and mode choice in the Greater Toronto Area
Authors: Day Nicholas , Habib Khandker Nurul , Miller Eric J.
Published: May 2010

This paper focuses on examining and analyzing observed trends in work trip making in the Greater Toronto Area (GTA). Commuter trip timing and mode choice behaviour are investigated to explain the main reasons behind peak spreading observed in cordon count data from 1975 through 2004 and to better understand the relationship between modal and temporal decisions. From analysis it becomes clear that significant differences exist in the trip timing trends of individuals choosing different modes. Multinomial logit mode choice models are developed for separate occupation groups, revealing significant differences in the mode choice preferences between occupation groups. Such differences are related to the differences in occupation-specific factors, including labour rates, work hour rules, free parking availability, and the spatial distribution of work locations. Overall, the investigations of this paper indicate that a joint analysis and modelling of trip timing and mode choice has considerable merit in travel demand models.
Long-term behaviour model of skid resistance for asphalt roadway surfaces
Authors: Echaveguren Tomas , de Solminihac Hernán , Chamorro Alondra
Published: May 2010

Skid resistance (SR) is relevant to road safety. Several researchers have showed that SR diminishes its value over time depending on the traffic-aggregated interactions, and the presence of heavy vehicles in the traffic stream. The classical SR model shows that its value drops from a starting value to an equilibrium value over time. However, this behaviour in low-volume roads is not entirely true. In this paper, an SR model in a single mathematic specification is proposed, which considers the polishing effect of heavy traffic through the polishing equivalence factor. The model was calibrated by using data measured with a SCRIM device from 1100 test sections in Chile. Considering speed and temperature factors calibrated for Chile, data were processed and corrected. It was concluded that the model for long-term behaviour of SR is satisfactory, but it is necessary to include the seasonal effects for a more realistic model.
Sewage sludge treatment by a continuous microwave enhanced advanced oxidation processA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Yu Y. , Chan W.I. , Lo I.W. , Liao P.H. , Lo K.V.
Published: May 2010

A continuous flow mode of the microwave enhanced advanced oxidation process (MW/H2O2-AOP) was used for sludge treatment as opposed to a batch operation mode from past studies. The effects of pre-microwave heating, microwave irradiation and post-microwave holding on organic matter solubilization were studied. Pre-microwave heating did not improve the overall orthophosphate solubilization, but helped in organic matter solubilization. Nutrients and organic matter were found to have increased during the post-microwave holding period, indicating overall sludge solubilization can be more effective when maintained at a high temperature after treatment with the MW/H2O2-AOP. It was beneficial to operate a continuous mode of the MW/H2O2-AOP at a longer retention time for organic matter solubilization, and at a shorter retention time for orthophosphate solubilization. Sludge settleability was greatly improved with the microwave treatment, with or without the addition of H2O2. The pre-heating of sludge before treatment with the microwave process by the means of heat exchange can be beneficial for the overall organic matter solubilization in the MW/H2O2-AOP.
Apport de la microcalorimétrie dans la taxonomie de quelques groupes d'Enterobacteriaceae
Authors: Herman J. P. M. , Jakubczak E. , Izard D. , Leclerc H.
Published: May 2010

The thermogenesis of 17 strains belonging to 12 species of the Enterobacteriaceae family was measured at 30 °C with an ampoule microcalorimeter. It was analyzed qualitatively (aspect of profiles) and quantitatively (total heat evolved, thermogenesis duration, maximum thermal power). The value of these criteria is discussed with respect to their discriminating value in the classification of bacteria. The information obtained may concur with the identification of species; it gives ground to reconsider actual phenotypes and genotypes and taxonomy generally. [Journal translation]
Superoxide dismutase from nitrogen-fixing Azotobacter chroococcum: purification, characterization, and intracellular location
Authors: Buchanan Alfred G. , Lees H.
Published: May 2010

Superoxide dismutase (SOD, EC 1.15.1.1) from nitrogen-fixing Azotobacter chroococcum was purified and identified as being similar to the manganese SOD of other procaryotes. The enzyme was relatively thermostable and insensitive to cyanide. A molecular weight of approximately 33 000 was estimated. Superoxide dismutase was found to be cytoplasmic (not bound to cell membranes) in A. chroococcum, but some enzyme was released by sonication of membrane vesicles.
A survey of microorganisms for thermonuclease production
Authors: Park C. E. , Serrano A. de Melo , Landgraf M. , Huang J. C. , Stankiewicz Z. , Rayman M. K.
Published: May 2010

A total of 1204 cultures comprising 16 genera were surveyed for production of thermonuclease (TNase) in milk. Cultures other than Staphylococcus capable of TNase production were restricted to two genera, Streptococcus and Bacillus. Nineteen percent of 338 group D streptococci comprising four species (85% of which were Streptococcus faecalis) and 17% of 60 streptococci belonging to other groups produced TNase. Nine percent of 130 Bacillus cultures comprising six species produced the enzyme. On the other hand, 99% of coagulase-positive staphylococci produced TNase and only 18% of the coagulase-negative staphylococci produced the enzyme. The amount of TNase produced by streptococci and bacilli was significantly lower than that produced by coagulase-positive staphylococci. The pH profile of the streptococci and Bacillus TNases was similar to that of the staphylococcal TNase; each enzyme exhibited a minor peak at pH 7.0 and a broad major peak ranging from pH 8.5 to 10. The nuclease produced by coagulase-positive Staphylococcus was more heat stable than the nucleases produced by Streptococcus and Bacillus; there was little loss in activity of the staphylococcal enzyme after 60 min at 100 °C, whereas 50% of the activity of the streptococcal and Bacillus nucleases was destroyed in 40–60 min and 60–80 min, respectively.
A simple low cost apparatus for conditioning large volumes of water for virological analysis
Authors: Payment Pierre , Trudel Michel
Published: May 2010

A simple low cost proportioning injector can effectively add chemicals such as aluminum chloride, hydrochloric acid, and sodium thiosulfate, to condition large volumes of water to detect viruses by adsorption to selected filters.