bluuebunny/crossref_metadata_2025 huggingface dataset:
5-Methyl-1,3,4-thiadiazolyl-(2-azo-6)-3,4-dimethylphenol as new analytical reagent
Authors: Cacho Juan , Nerin Cristina , Ruberte Laura
Published: March 2011

A synthesis of the new reagent 5-methyl-1,3,4-thiadiazolyl-(2-azo-6)-3,4-dimethylphenol (MTDADF) is described. The dissociation constant of the OH group is determined by spectrophotometry (pKa = 7.88 ± 0.05). the reaction of MTDADF with Ni(II) is quantitatively studied. Beer's law is obeyed of 0-2.4 ppm of Ni(II), the optimum range being 0.4 to 2.0 ppm, as deduced from a Ringbom graph. The stoichiometry of the complex corresponds to the ML2 type. Many other ions interfere seriously in the determination of Ni(II).
Semi-empirical MO study of refractions modelling biochemical oxidation of ethanol
Authors: Krechl Jiří , Kuthan Josef
Published: March 2011

The EHT, CNDO/2 and INDO methods have been used to find the energetically most favourable arrangement of the supermolecules 1-methylnicotiniumamide cation (I - ethanol (II),I - ethoxide anion (III) and 1-methyl-1,4-dihydronicotinamide (IV) - protonated acetaldehyde (V). An attempt has been made to define with more precision these geometries with the use of the gradient optimization based on CNDO/2 wave functions. Quantum-chemical characteristics of the studied systems are discussed with respect to possible course of biochemical reactions.
MO study of molecular association of local anaesthetics of carbamate type
Authors: Remko Milan , Frecer Vladimír , Čižmárik Jozef
Published: March 2011

The quantum-chemical PCILO method has been used to study of molecular association of piperidinoethyl alkoxyphenylcarbamates. The self-association of this type of compounds has been studied with methyl phenylcarbamate as a simple model. The PCILO calculations indicate the open dimer with N-H...O=C hydrogen bond to be the most stable complex. Moreover, the PCILO method has been used fro study of intermolecular hydrogen bonds formed between oxygen and nitrogen atoms of -NH-COO- group of the title compounds and N-methylacetamide, N,N-dimethylacetamide, and phenol. The calculations have shown that the most stable hydrogen bonds are formed by carbonyl oxygen atom. Somewhat weaker hydrogen bonds are formed by N-H group. The weakest hydrogen bonds are formed by methoxyl oxygen atom of the -NH-COO- part of the drug.
Adsorption phenomena in solutions of some anthraquinonesulfonic acids: Factors responsible for postwaves
Authors: Savenko Eugeniya , Tedoradze Gurami
Published: March 2011

The comparison of the adsorption of anthraquinone-1,5-disulfonic, anthraquinone-1-sulfonic acids and respective reduced compounds shows that the appearance of polarographic adsorption waves is connected with partial (in the case of postwave) and complete (in the case of prewave) inhibition of the reduction process by the reduction products. The number of electrons involved in the reaction has been determined (n = 2 and 4 for di- and monoacid, respectively). Using rotating disc electrode the order of the electrode reaction equal to one has been found.
Thermal denaturation of complexes of DNA with sequential and random lysine containing polypeptides
Authors: Hausenblasová Zuzana , Votavová Hana , Bláha Karel , Šponar Jaroslav
Published: March 2011

Complexes of DNA with lysine containing sequential polypeptides and random amino-acid copolymers were studied using the method of thermal melting. The effect of lysine content, lysine distribution along the polypeptide chain and of the lysine/nucleotide input ratio on the melting pattern was determined. Polypeptide redistribution on DNA and reversibility of the DNA melting in individual transition were also tested. It was shown that the behavior of DNA complexes of polypeptides with relatively low density of lysine differed from that of lysine rich polypeptides due to a low degree of charge neutralization and to the possibility of polypeptide redistribution during melting in the former case. In the later case the binding was found to be essentially irreversible. Higher thermal stability and lower redistribution rate were obtained using complexes prepared by gradient dialysis as compared with those prepared by direct mixing.
Oxidation of acrolein to acrylic acid on vanadium molybdenum oxide catalyst; The reaction kinetics
Authors: Tichý Josef , Kůstka Jiří , Machek Jaroslav
Published: March 2011

The oxidation kinetics of acrolein have been studied in gas phase in the presence of vanadium molybdenum oxide catalyst. Using a through-flow apparatus with integral reactor, the effect has been studied of concentration of individual reaction components, i.e. acrolein, oxygen, steam and acrylic acid, on conversion degree of acrolein. The measurements have been carried out at atmospheric pressure. For evaluation of the kinetic data measured an equation has been suggested expressing dependence of the oxidation rate on the mentioned parameters.
The reactivity of amines in deamination reaction on alumina
Authors: Sedláček Jiří , Koubek Josef
Published: March 2011

The rates of deamination of a series of primary, secondary and tertiary amines on alumina were determined by the method of initial reaction rates. In addition quantum chemical calculations for the same series of amines were performed by semiempirical CNDO/2 method, the interaction of molecule with surface acid centre of the catalyst being modelled by protonation of the amino group. It was found that experimental reactivities correlate well with calculated properties of the C-N bond. This shows that the cleavage of this bond takes place in the rate determining step of the reaction, giving evidence for E1 elimination mechanism. The good correlation of the experimental with calculated data confirms the correctness of the concept of the molecular adsorption of the amine on the acid catalytic centre as the first phase of heterogeneously catalysed deamination reaction.
2-Arylfluoro[3,2-b]pyrroles
Authors: Krutošíková Alžbeta , Kováč Jaroslav , Kraľovičová Eva
Published: March 2011

Preparation of ethyl 2-(4-tolyl)-4H-furo[3,2-b]pyrrole-5-carboxylate, alkylation and hydrolysis of ethyl 2-phenyl- and 2-(tolyl)furo[3,2-b]pyrrole-5-carboxylate are described. Also the synthesis of 2-phenyl- and 2-(4-tolyl)-4H-furo[3,2-b]pyrroles and their N-methylated derivatives is presented.
Simple algorithm of decomposition of equational models of global simulation of complex systems
Authors: Vrba Josef
Published: March 2011

Simple algorithm is described for decomposition of equational sets forming mathematical models of complex chemical-process systems at their global simulation in unsteady state. The algorithm does not require calculation of powers of adjacent matrix as is usual with the currently used methods based on the theory of graphs. The needed numerical operations are performed on the given matrix of occurrence of variables in individual equation of the system only.
Antioxidant activity of N-phenyl-1,4-phenylenediamine and its derivatives in tetralin
Authors: Prusíková Miluše , Holčík Jan , Pospíšil Jan
Published: March 2011

Using data on the uptake of oxygen in the oxidation of tetralin (60 °C, initiated with 2,2'-azobis-(isobutyronitrile)), structural effects of N-(4-subst.phenyl)-1,4-phenylenediamines (I) and N-(4-subst.phenyl)-N'-isopropyl-1,4-phenylenediamines (II) influencing the inhibition of the oxidation were determined. In both types of the antidegradants the antioxidant activity is unfavourably affected by the presence of the methoxy group in position 4 of N-phenyl. N-(4-Alkylphenyl) derivatives possess efficiency comparable to, or lower than, that of 4-phenyl derivatives. Compared with II, the antioxidant properties of diamines I are generally better.
Theoretical study of the conformational arrangement of 3-benzylidene-2,4-pentanedione and its substructures
Authors: Zahradník Pavol , Hrnčiar Pavol
Published: March 2011

The quantum chemical PCILO method was employed for calculation of conformational maps of 3-benzylidene-2,4-pentanedione. The analogous conformational maps of simpler substructures were also investigated to enable investigating the respective interactions. Steric interactions of the acetyl group with the phenyl group and of both acetyl groups were found to play a dominant role. One acetyl group is turned by 60° from the s-cis position, the other is in an s-trans conformation when being in the energetically more favourable sterical arrangement. The obtained data were compared with the experimental results.
Reaction of 5-nitrofurfuryltrichloromethyl sulfone with aliphatic aldehydes. Synthesis of butadienes and cyclobutenes related to 5-nitrofuran
Authors: Jurášek Adolf , Geisbacher Daniel , Kováč Jaroslav
Published: March 2011

5-Nitrofurfuryltrichloromethyl sulfone (I) reacts with piperidine or morpholine to give 1-(5-nitro-2-furfuryl)-2-piperidyl-2-piperidinosulfonylethylene (II) or 5-nitro-2-furoylmorpholinosulfonylmethane (III). α,β-Unsaturated sulfones, obtained by condensation of the sulfone I with aliphatic aldehydes, containing an acidic hydrogen at α-carbon (RCH2CHO, R = CH2, C2H5, C6H5), undergo an allylic rearrangement by the action of pyridine, triethylamine or tributylamine to yield butadienes or cyclobutenes derived from 5-nitrofuran. The mechanism of formation of the respective products is proposed and the spectral data (1H NMR, IR, UV and mass spectra) are interpreted.
On hydroboration of 2-allyl-1,2,3,4-tetrahydroisoquinoline
Authors: Ferles Miloslav , Kafka Stanislav
Published: March 2011

Heating of 2-allyl-1,2,3,4-tetrahydroisoquinoline (I) with triethylamine-borane afforded 7,8-benzo-5-aza-1-boraspiro[4,5]decane (II) which was hydrolyzed with hydrochloric acid to 3-(1,2,3,4-tetrahydro-2-isoquinolyl)propylboronic acid hydrochloride (III). Ethanolysis of II led to the diethyl ester IV. Compounds II and III were oxidizes to give 3-(1,2,3,4-tetrahydro-2-isoquinolyl)-1-propanol (V).
Oxidative transformations of some pyrimidine derivatives into oxazolidine derivatives
Authors: Křepelka Jiří , Pouzar Vladimír , Schlanger Jiří , Holubek Jiří , Körbl Jiří , Jančik Fedir , Kotva Rudolf
Published: March 2011

The action of dilute hydrogen peroxide in aqueous alkaline solutions on compounds I-VI and XX produced derivatives of 2-iminooxazolidine-4-one, VII-XI and XXI. Their structures were demonstrated by spectral comparison with hydantoin derivatives XXII, XXIV and XXV, which were prepared from 2-aminoalkanedioic acids XXVIII, XXX and XXXI by reaction with potassium cyanate, followed by ring closure induced by a mineral acid. The structure of compound X was revealed by basic hydrolysis to 2-hydroxy-1,7-heptanedioic acid (XXVII) and by conversion of the latter, in an acid medium, into a derivative of oxazolidine-2,4-dione, XXIX. To elucidate the probable mechanism of the oxidative transformation, compound IV was converted by oxidation in an acid medium into the 5-hydroxy derivative XXXII. Exposure of the latter to an alkaline medium gave compound X. Bromination of acid IV with bromine, or with a mixture of potassium bromide and bromate in an acid solution, afforded the 5-bromo derivative XXXIV. Analogously, reaction of the acid IV with a mixture of hydrogen peroxide and hydrochloric acid gave the 5-chloro derivative XXXV. Boiling the compound XXXIV in aqueous sodium hydroxide led to the acid IV and a smaller amount of compound X. Reaction of the compound X with morpholine yielded the morpholine analogue XXXVI. In the screening for antineoplastic activity, compounds XXXII and XXXVI showed weak antitumors effects with some types of experimental tumors. Compound X was quite ineffective in the general pharmacological screening.
The application of microprocessors in electrochemistry
Authors: Pospíšil Lubomír , Štefl Miroslav
Published: March 2011

A microcomputer based on Intel SDK 80 and an arithmetic microprocessor is described. The design and interfacing was made in such a way in order to fulfill most of the electrochemical measurements. The application to the staircase voltammetry and FFT admittance measurements is described.
Quantitative description of the changes in the acid-base properties of bromocresol green in the presence of submicelle and micelle concentrations of cationic tenside-Septonex
Authors: Havel Josef , Burešová-jančářová Irena , Kubáň Vlastimil
Published: March 2011

The effect of cationic surface-active substances - tensides - on the acid-base and optical properties of anionic organic analytical reagents was studied by spectrophotometric methods on the example of bromocresol green with Septonex in the submicelle and micelle tenside concentration regions. The acid-base properties of bromocresol green under the given experimental conditions depend on the concentrations of the tenside and reagent and on the type and concentration of the inert electrolyte. Changes in the conditional dissociation constant of the reagent were quantitatively described by equations that were derived from the relationships for the dissociation constant of the acid-base transition of the reagent LH/L-, the equilibrium constant for formation of the stoichiometric ion-associates between the tenside T+ and the anionic acid-base form of the reagent L- or the anion of the inert electrolyte X- and the equilibrium constant for formation of the polymeric micelle aggregates (T+)n. The experimental values of the conditional dissociation constants for bromocresol green for various tenside or inert electrolyte concentrations are in good agreement with these theoretically derived relationships.
Substituent effect in addition of cyanide ion to p-substituted 1-benzyl-3-carbamoylpyridinium chlorides
Authors: Pavlíková-Raclová Františka , Kuthan Josef
Published: March 2011

The rate constants k2 and equilibrium constants K = k2/k-2 of the title process (A) have been measured in aqueous solutions of eight quaternary salts of nicotinamide I (R = p-XC6H4CH2) at 298 K. The substituent effects of X = CH3O, CH3, H, F, Cl, COOCH3, CN, and NO2 exhibiting the Hammett dependence have been correlated with half-wave potentials of reduction of the depolarizers I, and the correlation results have been discussed with respect to mechanism of the reaction (A).
Chiroptical properties of pyrrolidine derivatives
Authors: Červinka Otakar , Sedlák Ilja , Strejček František
Published: March 2011

CD spectra of (S)-(-)-2-phenyl-1-methylpyrrolidine (I) and (S)-(-)-1-methyl-2-(2-tolyl)pyrrolidine (II) were calculated. Rotational strengths were calculated by direct procedure based on the CNDO/S-CI wave function. The most stable conformations were determined by total gradient optimization of molecular geometry and their molar fractions were calculated. CD spectra, constructed from the molar fractions and rotational strengths, agreed well with the experimental ones. Absolute configuration of compound II was established by the chemical correlation with (S)-(-)-hygrinic acid.
Study of chiroptical properties of some piperidine derivatives
Authors: Červinka Otakar , Fábryová Anna , Šňupárek Vladimír , Strejček František
Published: March 2011

Chiroptical properties of (S)-(-)-1-methyl-2-phenylpiperidine and (S)-(-)-1-methyl-2-(2-tolyl)piperidine have been studied. The preferred conformations have been calculated in gradient way on the basis of the CNDO/2 method, and the rotational forces have been calculated for them by direct procedure using the CNDO/S-CI wave function. For comparison of theory and experiment, molar fractions of the individual conformers have been calculated and used together with the rotational forces for construction of the CD spectrum which has been compared with the experimental CD spectrum. Absolute configurations of the mentioned compounds have been determined by chemical correlation.
Heat transfer in turbulent flow at very low Prandtl numbers
Authors: Vašák František , Kolář Václav , Brož Zdeněk
Published: March 2011

An analysis is performed of available experimental data on heat transfer in the region of very low Prandtl numbers 0.005 ⪬ Pr ⪬ 3. None of the verified models on heat transfer mechanism agrees with experimental data in the whole studied region. With regard to a small number of experimental data it is not possible to make a final decision whether the disagreement is due to inacuracies in experiments or on the side of theory.
Preparation of unsaturated nitriles
Authors: Procházka Miloš , Široký Miroslav
Published: March 2011

The yield and the rate of formation of nitriles X-CH=CH-CN and 3- and 4-substituted nitriles X-C6H5CN (X = CH3; OR; SR; COOCH3) were investigated in the reaction of vinyl and aryl bromides with CN(-), under catalysis with Pd0 and macrocyclic polyethers, and in the reaction with CuCN in dipolar aprotic solvents. Individual procedures were compared from the point of view of the possibility of a preparative utilization.
The mechanism of formation of 2,7-dimethyl-2,6-octadiene in the synthesis of 3-methylene-7-methyl-1,6-octadiene
Authors: Bartoň Jan , Kmínek Ivan
Published: March 2011

2,7-Dimethyl-2,6-octadiene is formed in the catalytic solution for the dimerization of 2-methyl-1,3-butadiene to β-myrcene (3-methylene-7-methyl-1,6-octadiene), as revealed by mass spectrometry and 13C NMR spectroscopy. Visual observations together with the results of gas chromatographic analysis of the catalytic solution suggest that the formation of 2,7-dimethyl-2,6-octadiene is associated with the transition of the alkali metal (sodium) from the solid phase into the solution. A reaction pathway is suggested accounting for the formation of 2,7-dimethyl-2,6-octadiene in the system.
Verification of the calculation of the constant-volume heat capacity difference of substances in the liquid and gas phases from the temperature dependence of heat of vaporization
Authors: Uchytilová Věra , Svoboda Václav
Published: March 2011

The possibilities were verified of the proposed method for calculating the difference between constant-volume heat capacities of liquids and gases in the ideal state from known data on the volumetric behaviour and temperature dependence of heats of vaporization of pure substances.
On the structural and magnetic properties of K3CrTe3O12, Na3CrTe3O12 and NaCrTe2O8
Authors: Danihelka Pavel
Published: March 2011

K3CrTe3O12, Na3CrTe3O12, and NaCrTe2O8 were obtained by reacting telluric acid or amorphous potassium tellurate with molten alkali dichromates, and their structural and magnetic properties were studied. The three substances are paramagnetic, with magnetic moments corresponding to the chromium oxidation state III. The sodium compounds obey the Curie-Weiss law up to the temperature of decomposition, the potassium compound follows this law up to a temperature of 800 K, above which the magnetic moment of chromium decreases probably on account of a partial reversible oxidation of chromium by the tellurium(VI) present. The three substances investigated were indexed in the tetragonal system and their lattice parameters were calculated. The two sodium salts involve the same basic structure motiv, viz. Te12O4824-.
Study of pumping effect in flow-through electrolysers
Authors: Roušar Ivo , Provazník Michal , Stuhl Pavel
Published: March 2011

In electrolysers with recirculation, where a gas is evolved, the pumping of electrolyte from a lower to a higher level can be effected by natural convection due to the difference between the densities of the inlet electrolyte and the gaseous emulsion at the outlet. An accurate balance equation for calculation of the rate of flow of the pumped liquid is derived. An equation for the calculation of the mean volume fraction of bubbles in the space between the electrodes is proposed and verified experimentally on a pilot electrolyser. Two examples of industrial applications are presented.
The effect of counterion on alkali ion-crown complex formation: A near-paradox in dissociating solvents
Authors: Závada Jiří , Pechanec Václav , Kocián Oldřich
Published: March 2011

Contrary to the widespread belief that counterion influences stability of charged complexes only in poorly solvating media, a dramatic effect of anion was discovered, ebulliometrically, in 0.6 molal M+X--C2H5OH (M = K, Na, Li; X = SCN, OC2H5) and in 0.6 molal M+X--H2O (M = K; X = SCN, OH) solution upon complexing with 18-crown-6,15-crown-5 and 12-crown-4. Out of the nine crown-MSCN combinations examined in the ethanolic solution, seven yielded 1 : 1 (18-crown-6-KSCN, 18-crown-6-NaSCN, 15-crown-5-NaSCN, 15-crown-5-LiSCN, 12-crown-4-KSCN) or 2 : 1 (15-crown-5-KSCN, 12-crown-4-NaSCN) complexes quantitatively, whereas the corresponding crown-MOC2H5 combinations did not complex at all or the complexation was very incomplete. An analogous situation was found in the aqueous solution, with KSCN complexing 18-crown-6 quantitatively or 15-crown-5 and 12-crown-4 partly, whereas KOH did not yield complexes with any of the three crowns. Evidence is presented that the observed effect of anion does not originate from ion-pairing.
A mass spectral study of O-aroylbenzohydroximoyl chlorides
Authors: Varella Evangelia A. , Alexandrou Nicholas E. , Exner Otto
Published: March 2011

Fifteen O-aroylbenzohydroximoyl chlorides IIa-IIo have been synthesized and their fragmentation pattern upon electron impact studied. Evidence has been obtained of a Lossen-Tiemann type rearrangement with aryl migration to nitrogen.
Anion radicals of beta diketonates
Authors: Staško Andrej , Malík Ľubomír , Pelikán Peter , Reguli Ján
Published: March 2011

Formation of anion radicals [RCOCHCOR']- with R ≡ R' = Me, i-Pr, t-Bu, and with R = Me, R' = Ph has been observed in reactions of beta diketonates wih Grignard reagents. The splitting constant of the methine proton is 0.26 mT, and that of the methyl protons is 1.2 mT if R ≡ R' = Me. According to INDO calculations the anion radical is stabilized with Ni2+ counterion in tetrahedral arrangement.
Degradation-insertion reactions of decaborane(14) with inorganic salts
Authors: Baše Karel
Published: March 2011

Decaborane(14) reacts with NaNO2 in tetrahydrofuran forming the [9-tetrahydrofuran-6-NO2B10H12]- salt which after protonization with concentrated H2SO4 or diluted HCl affords azaboranes 6-NB9H12 and 4-NB8H13, respectively. The 6-NB9H12 azaborane is hydrolyzed to the 4-NB8H13 azaborane and reacts with Lewis bases under the formation of the 9-L-6-NB9H12 ligand derivatives (L = (CH)S, CHCN, (CH)P). By the reduction of 9-CHCN-6-NBH with LiAlH4 in tetrahydrofuran the 6-NB9H13- anion was prepared. By an analogous reaction of decaborane(14) with KHSO3 in water and by a subsequent protonization of the formed intermediate with concentrated H2SO4 or diluted HCl the thiaboranes 6-SB9H11 and 4-SB8H12, respectively, were prepared. The reaction of decaborane(14) with Na2SeO3 in tetrahydrofuran followed by the protonization of the intermediate with diluted HCl afforded the 7,8-Se2B9H9 species. Structures of all compounds were proposed on the basis of the 11B and 1H NMR spectra; in the case of 4-NB8H13, the structure was determined by the X-ray diffraction analysis.
Detection of gross errors in chemical engineering measurements
Authors: Madron František
Published: March 2011

Detection of gross errors in chemical engineering measurements is studied, based on statistical analysis of redundant data. The error of third type has been defined as the unacceptably large error of a quantity which is the aim of measurement, while the gross error of measurement is not detected. The method of classification of directly measured quantities into disjoint subsets is described according to possible effective detection of occurence of gross errors of measurements by statistical analysis of measured data.
A contribution to the determination of 2-imidazolidinethione in mancozeb-type ethylene-bis-dithiocarbamate fungicides by high performance liquid chromatography
Authors: Bystrický Ľubor , Nátora Vojtech
Published: March 2011

The effect of conditions on the extraction-chromatographic determination of 2-imidazolidinethione (ETU) in mancozeb was investigated. The effect of the extraction time and presence of Na2SO4 is not critical if the samples are analyzed immediately after the extraction with methanol, but marked changes in the content of ETU and composition of the matrix appear if the samples are allowed to stand for a long period before the chromatographic treatment. The combined effects of heat, moisture and pH of medium leading to enhanced contents of ETU were also examined.
Similarity problems of the theory of unsteady concentration boundary layer
Authors: Wein Ondřej , Kovalevskaya N. D.
Published: March 2011

Using a new approximate method, transient course of the local and mean diffusion fluxes following a step concentration change on the wall has been obtained for a broad class of steady flow problems.
CNDO/S MO study of the fuchsone derivatives with sterically crowded exocyclic double bond
Authors: Musil Lubomír , Koutek Bohumír , Velek Jiří , Krupička Josef , Souček Milan
Published: March 2011

The electronic absorption spectra of 2-methyl-, 3-methyl-, 2,6-dimethyl-, 3,5-dimethyl- and 2,3,5,6-tetramethylfuchsone were investigated. The interpretation was carried out by comparing the spectra with those of the suitable model compounds and by quantum chemical (CNDO/S) analysis of the chromophoric systems of 4-benzhydrylidene-, 4-benzylidene- and 4-(9-fluorenylidene)-2,5-cyclohexadien-1-one. Within this approach also the effects were investigated of torsion and distortion of the double bond on spectral parameters of ethylenic chromophore. The knowledge thus obtained allowed us to suggest a plausible mechanism of the response of fuchsone derivatives to steric crowding of the exocyclic double bond region and to explain in a reasonable way the anomalous bathochromic shift and hypochromic effect exhibited by the long wavelength UV absorption band of 3,5-dimethyl- and 2,3,5,6-tetramethylfuchsone. The suggested interpretation corresponds well also with trends of half-wave potentials of these compounds.
A contribution to mechanism of addition of hydrogen bromide to the α,β-unsaturated system of 3-phenyl-2-propenoic acid
Authors: Červinka Otakar , Kříž Otomar
Published: March 2011

Rate of addition of hydrogen bromide to meta- and para-substituted 3-phenyl-2-propenoic acids I was followed by polarography and UV spectroscopy. Rate of protonation either is the overall rate determining step or is at least comparable with the rate of the subsequent nucleophile attack.
Oxidative elimination of phenyl group from α position of quaternary quinolinium salts
Authors: Nesvadba Petr , Kuthan Josef
Published: March 2011

Action of alkaline solution of potassium ferricyanide on the quaternary quinolinium salts IIIa to IIIc results in splitting off of 2-phenyl substituent and formation of the quinolones IVa-IVc. A possible mechanism of this transformation is discussed.
Depression of DNA synthesis in the thymus of zinc-treated adult mice
Authors: Čihák Alois , Mesa Milagros Carcia , Inoue Hideo
Published: March 2011

Zn-ions in a high dose affect the uptake of thymidine into thymus DNA. The depression of DNA synthesis in the thymus of zinc-treated mice is dose-dependent and is more pronounced in adult than in young animals.
Electrostatic effects on conformational equilibria: Alkyl 2-cyanobenzoates and 3-cyanopropenoates
Authors: Exner Otto , Friedl Zdeněk , Fiedler Pavel
Published: March 2011

The conformational equilibrium ap ⇌ sp of the title compounds was investigated by two methods: dipole moment measurement in benzene solution and IR spectroscopy of the carbonyl band in decahydronaphthalene solution. Approximately 71% of the ap rotamers were found for 2-cyanobenzoates (II, III), and between 60 to 80% for (Z)-3-cyanopropenoates (V, VI). This result does not reveal any special attractive interaction between the carbonyl oxygen and cyano carbon atoms; on the other hand, it is in fair agreement with electrostatic calculations based on point charges calculated from bond moments. Any attractive interaction was not detected even on aliphatic cyano esters VII-IX. Comparison of several model compounds and several kinds of approximative calculations leads us to conclude that the electrostatic model works generally better for conformational equilibria than for ionization equilibria.
Work function and UPS studies of propylene and cyclopropane adsorption on palladium surfaces
Authors: Bastl Zdeněk
Published: March 2011

The Kelvin vibrating capacitor method was used to measure the work function changes of vacuum deposited thin palladium layers in propylene adsorption. The work function change found for the propylene-saturated surface is, within the experimental error, identical with the change observed in the adsorption of cyclopropane and equal -1.085 ± 0.07 eV. Propylene and cyclopropane adsorption leads in the region of higher surface coverages to similar difference UV photoelectron spectra, exhibiting emission bands located at 6.7, 8.2 and 9.3 eV below the Fermi level. It is obvious from the results that at T ≈ 300 K, the adsorption of propylene and cyclopropane leads at higher coverages with high probability to similar surface complexes.
Bromination of 19-acetoxy-4β,5-cyclopropano-5β-cholestan-3-one
Authors: Joska Jiří , Fajkoš Jan , Zajíček Jaroslav
Published: March 2011

Bromination of the ketone II with Jacques' reagent afforded the dibromo ketone IV and the monobromo ketone V. On metal hydride reduction both bromo ketones gave the isomeric bromohydrins VIII, X, and XII the structures of which were established by standard reactions and by spectral evidence. Dehydrohalogenation of the bromo ketone V yielded the unsaturated ketone VII.
Hock burn: an indicator of broiler flock health
Authors: Hepworth P. J. , Nefedov A. V. , Muchnik I. B. , Morgan K. L.
Published: March 2011

This study aimed to identify risk factors for the prevalence of hock burn, a common disease of broiler chickens that influences the welfare and profitability of affected flocks, using hierarchical logistic regression analysis of routine flock management data. The study identified an association between hock burn and other diseases detected at slaughter and found that the management of flocks around the slaughter period was of particular importance for the control of hock burn, providing a rational basis for intervention.
TRIBIMAXIMAL MIXING IN NEUTRINO MASS MATRICES WITH TEXTURE ZEROS OR VANISHING MINORS
Authors: DEV S. , GUPTA SHIVANI , GAUTAM RADHA RAMAN
Published: March 2011

We study the existence of one/two texture zeros or one/two vanishing minors in the neutrino mass matrix with μτ symmetry. In the basis where the charged lepton mass matrix and the Dirac neutrino mass matrix are diagonal, the one/two zeros or one/two vanishing minors on the right-handed Majorana mass matrix having μτ symmetry will propagate via seesaw mechanism as one/two vanishing minors or one/two texture zeros in the neutrino mass matrix with μτ symmetry respectively. It is found that only five such texture structures of the neutrino mass matrix are phenomenologically viable. For tribimaximal mixing, these texture structures reduce the number of free parameters to one. Interesting predictions are obtained for the effective Majorana mass Mee, the absolute mass scale and the Majorana-type CP violating phases.
BOSE–EINSTEIN CONDENSATES IN A HOMOGENEOUS GRAVITATIONAL FIELD
Authors: RIVAS J. I. , CAMACHO A.
Published: March 2011

The behavior of a Bose–Einstein condensate in a homogeneous gravitational field is analyzed. We consider two different trapping potentials. Firstly, the gas is inside a finite container. The effects of the finiteness of the height of the container in connection with the presence of a homogeneous gravitational field are mathematically analyzed and the resulting energy eigenvalues are deduced and used to obtain the corresponding partition function and ensuing thermodynamical properties. Secondly, the trapping potential is an anisotropic harmonic oscillator and the effects of the gravitational field and of the zero-point energy on the condensation temperature are also considered. These results are employed in order to put forward an experiment which could test the so-called Einstein Equivalence Principle.
GRIBOV PROPAGATOR AND SYMMETRY BREAKING: A TOY MODEL
Authors: CHIFARELLI Y. E. , LEMES V. E. R.
Published: March 2011

The aim of this paper is to present a connection between the Gribov–Zwanziger condition for the mass gap and spontaneous symmetry breaking. In order to clarify these relationship, a toy model is presented and some quantum aspects are discussed.
PHOTO-CATALYTIC ACTIVITY AND PHOTO-ABSORPTION OF PLASMA-SPRAYED NANO-STRUCTURED TiO2 COATINGS
Authors: BOZORGTABAR MARYAMOSSADAT , SALEHI MEHDI , RAHIMIPOUR MOHAMMADREZA , JAFARPOUR MOHAMMADREZA
Published: March 2011

Titanium dioxide coatings were deposited by utilizing atmospheric plasma-spraying system. The agglomerated P25/20 nano-powder and different spraying parameters (e.g., Argon flow rate and spray distance) were used to determine their influences on the microstructure, crystalline structure, photo-absorption, and photo-catalytic performance of the coatings. The microstructure and phases of as-sprayed TiO 2 coatings were characterized by scanning electron microscope SEM and X-ray diffraction, respectively. Surface characteristics were investigated by Fourier Transform Infrared. Photo-catalytic efficiency of the elaborated samples was also determined in an environmental test chamber set-up and evaluated from the conversion rate of ethanol. The photo-absorption was determined by UV–Vis spectrophotometer. The as-sprayed TiO2 coating was photo-catalytically reactive for the degradation of ethanol. The photo-catalytic activity was influenced by spray conditions. It is found that the photo-catalytic activity is significantly influenced by anatase content, surface area, and surface state. The results showed that the argon flow rate has an influence on the microstructure, anatase content, and photo-catalytic activity of the TiO 2 coatings.
FIRST-PRINCIPLES STUDY OF NANODIAMOND DOPED WITH B AND N
Authors: WANG JIANGUANG , MA LI , ZHAO JIJUN
Published: March 2011

Nanodiamonds of different sizes doped with B and N impurities are studied by density functional theory. We find that the most stable sites for the B and N dopants are different. The substitutional B tends to stay in the middle region of a nanodiamond, while the energetically preferable site for N is on the surface of the nanodiamond. The chemical bonding and electronic properties of the B- and N-doped nanodiamonds are also discussed.
LAG FULL STATE HYBRID PROJECTIVE SYNCHRONIZATION IN DIFFERENT FRACTIONAL-ORDER CHAOTIC SYSTEMS
Authors: TANG YANG , FANG JIAN-AN , CHEN LIANG
Published: March 2011

In this paper, lag full state hybrid projective synchronization (LFSHPS) in fractional-order chaotic systems is first studied. We show that LFSHPS does exist in fractional-order chaotic systems. Based on active control theory, synchronization schemes for LFSHPS of the fractional-order chaotic systems are given. Numerical simulations are provided to illustrate and verify the effectiveness of the proposed methods.
SYNTHESIS OF CURRENT DIFFERENCING TRANSCONDUCTANCE AMPLIFIER-BASED CURRENT LIMITERS AND ITS APPLICATIONS
Authors: TANGSRIRAT WORAPONG , PUKKALANUN TATTAYA , SURAKAMPONTORN WANLOP
Published: March 2011

A synthesis of analog current limiter (CL) building blocks based on a current differencing transconductance amplifier (CDTA) is proposed. The breakpoint and the slope of the resulting transfer characteristic obtained from the proposed CDTA-based CL are electronically programmable through the external bias currents. To demonstrate versatility of the proposed electronically tunable CLs, some nonlinear applications to programmable current-mode precision full-wave rectifiers and piecewise-linear function approximation generators are also presented. PSPICE simulation and experimental results confirm the effectiveness of the proposed circuits.
COMPUTING NICE PROJECTIONS OF CONVEX POLYHEDRA
Authors: ASHRAFUL ALAM MD. , HASAN MASUD
Published: March 2011

In an orthogonal projection of a convex polyhedron P, the visibility ratio of a face f (of an edge e) is the ratio of orthogonally projected area of f (length of e) and its actual area (length). In this paper, we give algorithms for nice projections of P such that the minimum visibility ratio among all visible faces (among all visible edges) is maximized.
A PRACTICAL SYSTEM FOR ACOUSTIC SURVEILLANCE OF HAZARDOUS SITUATIONS
Authors: NTALAMPIRAS STAVROS , POTAMITIS ILYAS , FAKOTAKIS NIKOS
Published: March 2011

The present study describes a practical methodology for automatic space monitoring based solely on the perceived acoustic information. Our approach is based on a two stage recognition schema that detects and classifies sound events related to hazardous situations. The main objective is to identify on time abnormal events that may lead to life-threatening situations or property damage and forward detected sound events to an authorized officer for further evaluation of the cases. We consider the case where the atypical situations of screams, explosions or gunshots take place in a metro station environment. For describing the audio signals we constructed a feature vector which includes the Mel-frequency cepstral coefficients and three MPEG-7 low level descriptors. These are subsequently fed to hidden Markov models towards representing each sound category. The accuracy of the proposed method is tested under several SNR conditions.
A DYNAMIC POLYNOMIAL MUTATION FOR EVOLUTIONARY MULTI-OBJECTIVE OPTIMIZATION ALGORITHMS
Authors: HAMDAN MOHAMMAD
Published: March 2011

Polynomial mutation is widely used in evolutionary optimization algorithms as a variation operator. In previous work on the use of evolutionary algorithms for solving multi-objective problems, two versions of polynomial mutations were introduced. The first is non-highly disruptive that is not prone to local optima and the second is highly disruptive polynomial mutation. This paper looks at the two variants and proposes a dynamic version of polynomial mutation. The experimental results show that the proposed adaptive algorithm is doing well for three evolutionary multiobjective algorithms on well known multiobjective optimization problems in terms of convergence speed, generational distance and hypervolume performance metrics.
FRACTAL APPROACH TO IDENTIFY THE GRADE OF CERVICAL CANCER
Authors: JAYALALITHA G. , UTHAYAKUMAR R.
Published: March 2011

This paper presents the method of grading of cervical cancer images according to cell formation in the tissue. The variation of intensity and texture complexity of cancer cell images are calculated by fractal dimension methods. Box Counting Method ( D B) and HarFA Programme software are used to find out the dimension of the cells. Contact model and Epidemic Model are the two different models used here. The contact model shows the contact of the cells and the formation of the cancer in the part of the organ. The Epidemic model shows the growth of cancer. Lacunarity is formed between the cells. If the Lacunarity increases the dimension also increases. On seeing the growth of the cancer cell the pathologist can determine the grade of the cancer which in turn will help him to diagnose the cervical cancer and recommend appropriate treatment.
ON THE VISUALIZATION OF STRINGS AND FRACTALS OF SOME FORBIDDEN WORDS
Authors: HUANG CHENGXING , LI JIANPING , PENG SHOULI
Published: March 2011

By using the frame representation method proposed by B. L. Hao et al. in 20001,2 and a method provided by P. Tino,3,4 we will devise the generalized graphical representation for the strings defined on an alphabet Σ = {0, 1, …, n - 1} with cardinal n but all these graphs are still shown in a unit square, and generate its corresponding struture tables automatically. In particular, the words defined on Σ are mapped into n-adic numbers so that the index set Ind(B) can be computed. Thus, the fractals of the forbidden words can be naturally constructed. It has already been known that for biological sequences, the circular codes can be applied to some special bacteria and their forbidden words are the 5-necklaces. In this paper, we notice that the fractals of the forbidden words are particularly useful to represent the circular codes for some biological sequences.
THE NEWTON–RAPHSON METHOD AND ADAPTIVE ODE SOLVERS
Authors: SCHNEEBELI HANS RUDOLF , WIHLER THOMAS P.
Published: March 2011

The Newton–Raphson method for solving nonlinear equations f(x) = 0 in ℝn is discussed within the context of ordinary differential equations. This framework makes it possible to reformulate the scheme by means of an adaptive step size control procedure that aims at reducing the chaotic behavior of the original method without losing the quadratic convergence close to the roots. The performance of the modified scheme is illustrated with a few low-dimensional examples.
TANGENT MODELS AS A MATHEMATICAL FRAMEWORK FOR DYNAMIC CALIBRATION
Authors: CARMONA RENÉ , NADTOCHIY SERGEY
Published: March 2011

Motivated by the desire to integrate repeated calibration procedures into a single dynamic market model, we introduce the notion of a "tangent model" in an abstract set up, and we show that this new mathematical paradigm accommodates all the recent attempts to study consistency and absence of arbitrage in market models. For the sake of illustration, we concentrate on the case when market quotes provide the prices of European call options for a specific set of strikes and maturities. While reviewing our recent results on dynamic local volatility and tangent Lévy models, we present a theory of tangent models unifying these two approaches and construct a new class of tangent Lévy models, which allows the underlying to have both continuous and pure jump components.
MESHFREE COLLOCATION METHOD FOR IMPLICIT TIME INTEGRATION OF ODES
Authors: NETUZHYLOV HENNADIY , ZILIAN ANDREAS
Published: March 2011

An implicit time integration meshfree collocation method for solving linear and nonlinear ordinary differential equations (ODEs) based on interpolating moving least squares technique, which uses singular weights for constructing ansatz functions, is presented. On an example of a system of equations for Foucault pendulum, the flexibility of the proposed approach is shown and the accuracy, convergence, and stability properties are investigated. In a nonlinear case, the method gives accurate results, which is demonstrated by the solution of Lorenz equations. The typical trajectory patterns, e.g. butterfly pattern, were observed and the properties of the method are compared to those of a higher-order time integration method.
Synthesis, structural and spectroscopic properties of encapsulated Chlorophyll-a thin film in carboxymethyl cellulose
Authors: Wei Wong Y. , Periasamy Vengadesh
Published: March 2011

We report successful retention of the spectroscopic properties of Chlorophyll-a molecules encapsulated in carboxymethyl cellulose acting as an "artificial membrane" material. Films were prepared on indium tin oxide substrates utilizing the spin-coating technique at different concentrations of carboxymethyl cellulose aqueous solution. Results show that the native state of the encapsulated Chlorophyll-a molecules were retained for extended periods of time enhanced further by the optimum concentration effect. Investigations also revealed that the molecules exist in nanocrystal forms with crystal size of 10 nm regardless of the carboxymethyl cellulose concentrations and can be further optimized by varying the spin rates. Chlorophyll-a molecules were found well dispersed in the carboxymethyl cellulose films suggesting the suitability of the gel-like polymer solution as a dispersion agent. It was therefore obvious that the encapsulation of Chlorophyll-a molecules by carboxymethyl cellulose provides prolonged retention of its photoactivity highlighting extended usage when incorporated into future device applications.
Terahertz Birefringence in Zinc Oxide
Authors: Kim Youngchan , Ahn Jaewook , Kim Bog G. , Yee Dae-Su
Published: March 2011

The birefringence of zinc oxide (ZnO) in the terahertz (THz) frequency range is measured using a parallel-polarization configuration THz time-domain spectrometer and compared with the result of an ab initio calculation. The measured birefringence of 0.180 at 1 THz shows good agreement with the calculated value of 0.170 from full phonon consideration, both of which are about 20 times larger than the birefringence in the visible range. It is found that the difference of the transverse optical and longitudinal optical (TO–LO) phonon splitting between the optical phonon branches (A
1 and E
1) predominantly contributes to the huge birefringence of ZnO in the THz frequency region.
Efficient Nonvolatile Rewritable Memories Based on Three-Dimensionally Confined Au Quantum Dots Embedded in Ultrathin Polyimide Layers
Authors: Wu Chaoxing , Li Fushan , Guo Tailiang , Qu Bo , Chen Zhijian , Gong Qihuang
Published: March 2011

The electrical properties of a nonvolatile organic bistable device (OBD) utilizing Au quantum dots (QDs) sandwiched between two thin insulating polyimide layers were investigated. Current–voltage (I–V) measurements on the device at room temperature showed a current bistability due to the existence of the Au QDs. The maximum ON/OFF ratio of the current bistability in the OBD was 1 ×108, the largest value ever reported for a stable OBD. The device has excellent endurance and retention ability in ambient conditions. The electrical properties and operating mechanisms for the device are analyzed on the basis of the I–V results.
Ohmic Cathode Electrode on the Backside of m-Plane and (2021) Bulk GaN Substrates for Optical Device Applications
Authors: Hsiung Chia-Lin , Lin You-Da , Ohta Hiroaki , DenBaars Steven P. , Nakamura Shuji
Published: March 2011

Cathode electrodes on the backside of n-type nonpolar m-plane (1100) and semipolar (2021) GaN substrates after thinning were investigated. For m-plane, Al deposition after inductively coupled plasma exposure resulted in ohmic characteristics with a specific contact resistivity of 1.6 ×10-4 Ω cm2 without annealing, where the sub-micron-order pillar-like micromasking were considered to contribute to the ohmic contact. For (2021), ohmic characteristics with a specific contact resistivity of 6.9 ×10-5 Ω cm2 was confirmed with Ti/Al electrode after annealing at 500 °C. Such electrodes could improve wall-plug efficiencies of nonpolar and semipolar GaN-based optoelectronic devices.
Metamorphic evolution of the Tethyan Himalayan flysch in SE Tibet
Authors: Dunkl I. , AntolÍn B. , Wemmer K. , Rantitsch G. , Kienast M. , Montomoli C. , Ding L. , Carosi R. , Appel E. , El Bay R. , Xu Q. , Von Eynatten H.
Published: March 2011

The metamorphic conditions and the age of thermal overprint were determined in metapelites, metaarenites and metabasites of the Tethyan Himalayan Sequence (THS) in SE Tibet using Kübler Index and vitrinite reflectance data and applying thermobarometrical (Thermocalc and PERPLEX) and geochronological methods (illite/muscovite K–Ar and zircon and apatite (U–Th)/He chronology). The multiple folded thrust pile experienced a thermal overprint reaching locally peak conditions between the diagenetic stage (
c
. 170 °C) and the amphibolite facies (
c
. 600 °C at 10 kbar). Burial diagenesis and heating due to Early Cretaceous dyke emplacement triggered the growth of illite in the metapelites. Eocene collision-related peak metamorphic conditions have been reached at
c
. 44 Ma. During collision the different tectonic blocks of the THS were tectonically buried to different structural levels so that they experienced maximum greenschist to amphibolite facies metamorphism. Later, during Oligocene to Miocene times the entire THS underwent anchi- to epizonal metamorphic conditions, probably associated to continuous deformation in the flysch fold-thrust-system. This period terminated at
c
. 24–22 Ma. Adjacent to the north Himalayan metamorphic domes, the base of the THS was metamorphosed during Miocene times (
c
. 13 Ma). Post-metamorphic cooling below
c
. 180 °C lasted until Late Miocene and took place at different times.