bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of introducing low-frequency harmonics in the perception of vocoded telephone speech
Authors: Hu Yi , Loizou Philipos C.
Published: September 2010

Several studies have demonstrated that telephone use presents a challenge for most cochlear implant (CI) users, and this is attributed mainly to the narrow bandwidth (300–3400 Hz) introduced by the telephone network. The present study focuses on answering the question whether telephone speech recognition in noise can be improved by introducing, prior to vocoder processing, low-frequency harmonic information encompassing the missing (due to the telephone network) information residing in the 0–300 Hz band. Experiment 1 regenerates the main harmonics and adjacent partials within the 0–600 Hz range in corrupted (by steady noise) telephone speech which has been vocoded to simulate electric-acoustic stimulation (EAS). Results indicated that introducing the main harmonics alone did not produce any benefits in intelligibility. Substantial benefit (20%) was observed, however, when both main harmonics and adjacent partials were regenerated in the acoustic portion of EAS-vocoded telephone speech. A similar benefit was noted in Experiment 2 when low-frequency harmonic information was introduced prior to processing noise-corrupted telephone speech using an eight-channel vocoder. The gain in telephone speech intelligibility in noise obtained when low-frequency harmonic information was introduced can be attributed to the listeners having more reliable access to a combination of F0, glimpsing and lexical segmentation cues.
Beyond arousal: Valence and potency/control cues in the vocal expression of emotion
Authors: Goudbeek Martijn , Scherer Klaus
Published: September 2010

The important role of arousal in determining vocal parameters in the expression of emotion is well established. There is less evidence for the contribution of emotion dimensions such as valence and potency/control to vocal emotion expression. Here, an acoustic analysis of the newly developed Geneva Multimodal Emotional Portrayals corpus, is presented to examine the role of dimensions other than arousal. This corpus contains twelve emotions that systematically vary with respect to valence, arousal, and potency/control. The emotions were portrayed by professional actors coached by a stage director. The extracted acoustic parameters were first compared with those obtained from a similar corpus [Banse and Scherer (1996). J. Pers. Soc. Psychol. 70, 614–636] and shown to largely replicate the earlier findings. Based on a principal component analysis, seven composite scores were calculated and were used to determine the relative contribution of the respective vocal parameters to the emotional dimensions arousal, valence, and potency/control. The results show that although arousal dominates for many vocal parameters, it is possible to identify parameters, in particular spectral balance and spectral noise, that are specifically related to valence and potency/control.
Analytical modeling of sound transmission across finite aeroelastic panels in convected fluids
Authors: Xin F. X. , Lu T. J.
Published: September 2010

An analytical approach is formulated to account for the effects of mean flow on sound transmission across a simply supported rectangular aeroelastic panel. The application of the convected wave equation and the displacement continuity condition at the fluid-panel interfaces ensures the exact handling of the complex aeroelastic coupling between panel vibration and fluid disturbances. To explore the mean flow effects on sound transmission, three different cases (i.e., mean flow on incident side only, on radiating side only, and on both sides) are separately considered in terms of refraction angular relations and sound transmission loss (STL) plots. Obtained results show that the influence of the incident side mean flow upon sound penetration is significantly different from that of the transmitted side mean flow. The contour plot of refraction angle versus incident angle for the case when the mean flow is on the transmitted side is just a reverse of that when the mean flow is on the incident side. The aerodynamic damping effects on the transmission of sound are well captured by plotting the STL as a function of frequency for varying Mach numbers. However, as the Mach number is increased, the coincidence dip frequency increases when the flow is on the incident side but remains unchanged when in the flow is on the radiating side. In the most general case when the fluids on both sides of the panel are convecting, the refraction angular relations are significantly different from those when the fluid on one side of the panel is moving and that on the other side is at rest.
A hybrid scheme for bore design optimization of a brass instrument
Authors: Noreland J. O. Daniel , Udawalpola M. Rajitha , Berggren O. Martin
Published: September 2010

This paper presents how the shape of a brass instrument can be optimized with respect to its intonation properties. The instrument is modeled using a hybrid method between a lossy one-dimensional transmission line analogy for the slowly flaring part of the instrument, and a two-dimensional finite element model for the rapidly flaring part. The optimization employs gradient-based algorithms, and allows for a large number of design variables. Through the use of an appropriate choice of design variables, the algorithm is capable of rapidly finding horn profiles that are optimal subject to various geometric constraints, such as increasing or convex bell flares. It is found that under a convexity constraint, brass wind bells that are optimal with respect to an intonation condition can be constructed of piecewise conical sections.
Accounting quantitatively for sensitivity to envelope-based interaural temporal disparities at high frequencies
Authors: Bernstein Leslie R. , Trahiotis Constantine
Published: September 2010

Bernstein and Trahiotis [(2009). J. Acoust. Soc. Am. 125, 3234–3242] reported threshold interaural temporal disparities (ITDs) conveyed by the envelopes of 4-kHz-centered “raised-sine” stimuli. A raised-sine stimulus consists of a carrier modulated by a sinusoid raised to an exponent. Such stimuli permitted Bernstein and Trahiotis to vary, independently, stimulus modulation frequency, modulation depth, and “relative peakedness/deadtime.” An interaural correlation-based model that included stages mimicking peripheral auditory processing captured most of the data save for an overestimation of threshold ITDs obtained when the depth of modulation was 25% and the raised-sine exponent was 8.0. The purpose of the present study was: (1) to present a quantitative evaluation of how well other measures, including normalized envelope fourth moment, envelope peakwidth, and envelope “deadtime” might also account for the data reported by Bernstein and Trahiotis and (2) to present new threshold ITDs measured while varying, factorially, depth of modulation, raised-sine exponent, and modulation frequency. Quantitative analyses of both the prior and the new data showed that the normalized interaural correlation, computed subsequent to peripheral auditory processing, provided the most accurate predictions. Importantly, the overestimation of threshold ITDs did not occur when it was assumed that listeners can employ information within “off-frequency” auditory filters.
Objective evaluation of the sweet spot size in spatial sound reproduction using elevated loudspeakers
Authors: Parodi Yesenia Lacouture , Rubak Per
Published: September 2010

In a previous study, three crosstalk cancellation techniques were evaluated and compared under different conditions. Least-squares approximations in the frequency and time domain were evaluated along with a method based on minimum-phase decomposition and a frequency independent delay. In general, the least-squares methods outperformed the method based on the minimum-phase decomposition. However, the evaluation was only done for the best-case scenario, where the transfer functions used to design the filters correspond to the listener’s transfer functions and his/her location and orientation relative to the loudspeakers. This paper presents a follow-up evaluation of the performance of the three inversion techniques when the above mentioned conditions are relaxed. A setup to measure the sweet spot of different loudspeaker arrangements is described. The sweet spot was measured for 21 different loudspeaker configurations, including two- and four-channel setups. Lateral and frontal displacement were measured along with head rotations. The setups were evaluated at different elevation angles. The results suggest that when the loudspeakers are placed at elevated positions, a wider effective area is obtained. Additionally, the two-channel configurations showed to be more robust to head misalignments than the four-channel configurations.
Acoustic fidelity of internet bandwidths for measures used in speech and voice disorders
Authors: Xue Steve An , Lower Amy
Published: September 2010

The purpose of this study was to explore the impact of different bandwidths on acoustic measures when using low-cost internet technology of teletherapy in the field of speech and language rehabilitation. Normal speech and voice samples were collected at a clinic and a remote place by connecting the computers to Skype and VoiceEmotion software, while the disordered speech samples were collected through teaching CD samples from a quality voice textbook. Pure tones at 200 and 1000 Hz were also collected. The acoustic parameters: average fundamental frequency (F0), jitter percent, shimmer percent and noise-to-harmonic ratio (NHR) were used for fidelity analysis. The average F0 increased across all samples and bandwidths. There was greater increase and variability on the disordered voice samples. Speaking F0 was shown to both increase and decrease in no identifiable pattern with the different bandwidths. Jitter, shimmer and NHR were significantly different on pre- and post-transmission trials. The study provided preliminary pilot data on the fidelity effect of internet transmission on acoustic variables for voice and speech. Cautious suggestions were also provided to speech and language therapists who would consider using teletherapy for speech and voice diagnosis and treatment.
A generalized approach for efficient finite element modeling of elastodynamic scattering in two and three dimensions
Authors: Velichko Alexander , Wilcox Paul D.
Published: September 2010

A robust and efficient technique for predicting the far-field scattering behavior for an arbitrarily-shaped defect in a generally anisotropic medium is presented that can be implemented in a commercial FE package. The spatial size of the modeling domain around the defect is as small as possible to minimize computational expense and a minimum number of models are executed. The method is based on an integral representation of a wave field in a homogeneous anisotropic medium. A plane incident mode is excited by applying suitable forces at nodes on a surface that encloses the scatterer. The scattered wave field is measured at monitoring nodes on a concentric surface and then decomposed into far-field scattering amplitudes of different modes in different directions. Example results for 2D and 3D bulk wave scattering in isotropic material and guided wave scattering are presented. Modeling accuracy is examined in various ways, including a comparison with the analytical solutions and calculation of the energy balance.
A method to enable a bottlenose dolphin (Tursiops truncatus) to echolocate while out of water
Authors: Finneran James J. , Houser Dorian S. , Moore Patrick W. , Branstetter Brian K. , Trickey Jennifer S. , Ridgway Sam H.
Published: September 2010

The study of site-specific brain activity associated with dolphin echolocation has been hampered by the difficulties inherent in administering radiolabels and performing medical imaging while a dolphin echolocates in an aquatic environment. To overcome these limitations, a system has been developed to allow a bottlenose dolphin to echolocate while out of the water. The system relies on a “phantom echo generator” (PEG) consisting of a Texas Instruments C6713 digital signal processor with an analog input/output daughtercard. Echolocation clicks produced by the dolphin are detected with a hydrophone embedded in a suction cup on the melon, then digitized within the PEG. Clicks exceeding a user-defined threshold are convolved with a target impulse response, delayed, and scaled before being converted to analog and transmitted through a sound projector embedded in a suction cup attached to the dolphin’s lower jaw. Dolphin in-air echolocation behavior, inter-click intervals, and overall performance were analogous to those observed during comparable underwater testing with physical targets, demonstrating that the dolphin was indeed performing an echolocation task while out of water.
Chaperoning mTORC1 Activity
Authors: Adler Elizabeth M.
Published: September 2010

Chaperone availability regulates mTORC1 signaling, providing a link between protein quality control and translation.
NF-κB: Much Learned, Much to Learn
Authors: Razani Bahram , Cheng Genhong
Published: September 2010

The book
NF-κB: A Network Hub Controlling Immunity, Inflammation, and Cancer
provides an overview of various aspects of NF-κB signaling.
Optimization of mobile phase composition in liquid chromatography
Authors: Vláčil František , Hamplová Věra
Published: September 2010

A simple method is suggested for the optimization of the mobile phase composition in isocratic reversed-phase liquid chromatography. The function f = Σ(Rs,i -Rso)2, where Rs,i is the attained resolution for two successive peaks and Rso is the desired resolution for the chosen time of analysis (hence, a chosen capacity ratio of the last component eluted), was used as the chromatographic response function. The minimum of this function, corresponding to the optimum state, can be found rapidly by the statistical simplex method. This approach was applied to the separation of Cu, Co, Ni, Pb, and Hg diethyldithiocarbamates in a reversed-phase system with silica gel-C18.
The course of consecutive reactions inside a nonisotropic catalyst particle, affected by internal difusion
Authors: Hanyka Jiří , Fialová Alena
Published: September 2010

A system of differential equations for consecutive reactions inside a nonisotropic catalyst particle under conditions of internal diffusion is solved. The system of diffusion equations for the spherical geometry of the catalyst grain is numerically solved by using the collocation method. The solution is sought for various radial activity profiles across the catalyst particle and for various values of Thiele's modulus for the two consecutive reactions. The effect of the reaction orders with respect to the reactants on the degree of utilization of the internal catalyst surface and on the reaction selectivity is examined.
Experimental study of the velocity of the flow of highly viscous Newtonian liquid in a curved rectangular duct
Authors: Seichter Pavel
Published: September 2010

Thermistor anemometer measurements in a curved rectangular duct and a straight circular cross section tube permitted verification of the theoretical values of tangential velocities computed on the basis of the solution of the Navier-Stokes equation for the drag isothermal and creeping flow of a Newtonian liquid. From comparison of the theoretical and experimental values there follows that the achieved agreement is acceptable.
Synthesis and reactions of 1,2-dicarba-closo-dodecarborane-1-yl tetrahydroborate(1-)
Authors: Plešek Jaromír , Jelínek Tomáš , Heřmánek Stanislav , Štíbr Bohumil
Published: September 2010

Preparation of the [1-H3B-1,2-C2B10H11]- anion in various ways is reported. The species is a substituted derivative of the [BH4]- anion and can be employed for obtaining a family of the 1-L-H2B-1,2-C2B10H11 (L = (CH3)2S, C5H5N, (CH3)3N, and (C2H5)3N base adducts. Constitution of all compounds isolated was established primarily on the basis of their 1H, 11B, and 13C NMR spectra.
Reactions of triterpenoid ketones with sulfur and morpholine under the conditions of Willgerodt-Kindler reaction
Authors: Sejbal Jan , Klinot Jiří , Protiva Jiří , Vystrčil Alois
Published: September 2010

19β,28-Epoxy-18α-oleanan-3-one (I) when heated with sulfur in morpholine gives rise to 2-oxo derivative II, accompanied by a small amount of the starting ketone I. The reaction can be controlled to that 2-oxo derivative II is formed almost exclusively. Derivatives III-VII with a keto group and a further functional group in the position 2 and 3 also give 2-oxo derivative II. In the same manner 3-oxo-18α-oleanan-28→19β-olide (XVIII) was converted to 2-oxo derivative XIX. 1-Oxo derivative VIII and A-nor-ketone IX do not react under these conditions. An addition of vicinal diamine into the reaction mixture leads to the formation of compounds XIII, XV - XVII, XX with pyrazine cycle condensed with the ring A.
Steroids with the β-crotonate (2-butenoate) side chain
Authors: Černý Ivan , Pouzar Vladimír , Drašar Pavel , Tureček František , Havel Miroslav
Published: September 2010

Ethyl (20E)-3β-methoxymethoxy-24-nor-5,20(22)-choladien-23-oate (Va) and analogous derivatives with 5α,5β and Δ5,14 steroid moiety (Vb,Vc and Vd, respectively) were prepared by Wittig-Horner reaction of the corresponding ketones IIa-IId with diethyl ethoxycarbonylmethylphosphonate. In this case the reaction affords exclusively the (E)-isomers, in contrast with the Peterson reaction with lithium salt of ethyl 2-(trimethylsilyl)acetate which gives a mixture of (E)- and (Z)-isomers at the Δ20(22) double bond. The structure of the products was confirmed by 1H NMR and 13C NMR spectroscopy. The crotonates Va-Vd were further converted into the 3-O-succinyl derivatives VIIIa-VIIId.
Liquid-liquid equilibrium in the system methanol-water-tert-amyl methyl ether
Authors: Linek Jan , Bernatová Svatoslava
Published: September 2010

Liquid-liquid equilibrium was measured in the system methanol (MEOH)-water(W)-tert-amyl methyl ether (TAME) at 20 °C. Nine tie-lines and the binary solubilities were correlated by the Rod method. A comparison is presented of the representation of experimental data in terms of the Rod method and the NRTL and UNIQUAC equation.
Vapour-liquid equilibrium in strongly associated systems. The systems acetic acid-propionic acid and acetic acid-trifluoroacetic acid
Authors: Malijevská Ivona , Sýsová Marie , Vlčková Dagmar
Published: September 2010

Vapour-liquid equilibrium was measured in the systems acetic acid-propionic acid and acetic acid-trifluoroacetic acid at normal pressure. Special emphasis has been laid on the correct expression of the P-V-T behaviour in the vapour phase and the analysis of the data obtained.
Post-proline endopeptidase. Interaction of the enzyme with substrates containing disulfide and thioether bond
Authors: Hauzer Karel , Barth Tomislav , Hauzerová Linda , Barthová Jana , Hrbas Pavel , Slaninová Jiřina , Jošt Karel
Published: September 2010

The free thiol group of post-proline endopeptidase (EC 3.4.21.26) can interact with the disulfide bridge contained in some of the substrates of this enzyme (neurohypophysial hormones and some of their analogues). The influence of these interactions on the activity of this enzyme was studied using several substances modelling individual types of interactions: thiol-disulfide exchange, catalytic interaction and a complex interaction including the two preceding types. Deamino-1-carba-oxytocin is catalytically hydrolysed in the concentration range up to 10-3mol/l, oxytocin and arginine-vasopressin are catalytically hydrolysed in concentrations of 10-5 to 10-8 mol/l. A reaction leading to inactivation of the enzyme prevails at concentrations of 10-3 to 10-4 mol/l. When inactivated by lower concentrations of arginine-vasopressin (up to a molar ratio of 1 : 1), the enzyme can be reactivated by incubation with dithiothreitol, higher concentrations of arginine-vasopresson cause irreversible enzyme inactivation.
Crystal and molecular structure of heptacain hydrochloride
Authors: Pavelčík František , Remko Milan , Čižmárik Jozef , Majer Jaroslav
Published: September 2010

The crystal and molecular structure of heptacain hydrochloride was determined from three-dimensional diffractometric data. The carbamate group was found to be rotated out of the benzene ring plane by 15.5°, whilst the piperidine ring is in a more stable chair conformation. The heptyloxy side chain is in a stable all-trans conformation. The structure was refined by the full matrix least-squares method to a final R value 0.1127 for the observed reflections.
Theory of polarography with elimination of some currents
Authors: Dračka Oldřich
Published: September 2010

A method for the elimination of various components of the polarographic current is proposed, based on its differentiation and/or integration with respect to time forming a linear combination of the results with the original current. A linear combination of n different functions can be used to eliminate n - 1 current components. Examples for the elimination of the charging, diffusion, and kinetic current are given, and the possibilities of realization and utilization of the new method are discussed.
The effect of surface active agents on the mass transfer coefficient in vertical film flow of liquid over the surface of expanded metal sheet packing
Authors: Brož Zdeněk , Endršt Mirko
Published: September 2010

Experimental data have been used on absorption of poorly soluble gases, helium, carbon dioxide, and propane, to study the mechanism of interfacial mass transfer in vertical gravitational film flow down the surface of the expanded metal sheet. It has been found that upon addition of surface active agents into water, the original almost freely moving liquid-gas interfacial surface behaves similarly as a liquid-solid surface. Two adjustable hydrodynamic parameters have been evaluated on the basis of the film penetration theory with the physical meaning of the dimensionless thickness of an unmixed region near the interface ϑ+ = 0.4 and the characteristic length < scale of the disturbance λ+ = 26.4.
The synthesis and stereochemistry of the ternary cobalt(III) complex with a stereospecific ligand derived from (S)-leucine
Authors: Strašák Milan , Novomeský Pavol
Published: September 2010

A new stereospecific ligand, ethylenediamine-N,N'-di(S)-α-isocapronic acid, was synthesized by condensation of (S)-leucine with 1,2-dibromoethane in alkaline aqueous medium. It follows from the 1H and 13C NMR spectra that the terminal methyl groups are chemically and magnetically nonequivalent. Of the four theoretically possible isomers of the ternary cobalt (III) complex with ethylenediamine, separation on catex yielded only one, whose absolute configuration was determined by a combination of 1H and 13C NMR, electron absorption spectroscopy and CD and IR spectroscopy.
Rhodium-diphosphine tosylate complexes as hydrogenation catalysts
Authors: Reiss Jiří , Hetflejš Jiří
Published: September 2010

Novel rhodium-diphosphine tosylate complexes of the type [Rh(COD)L2]+ (O3SC6H4CH3-p)- (L2 = diphos, prophos, buphos, (-)-DIOP) have been prepared in high yields (87-92%) by the displacement of acac ligand from Rh(COD)(acac)by p-toluenesulphonic acid in the presence of L2. The complexes were found to be efficient hydrogenation catalysts comparable in activity to know cationic rhodium complexes. Some differences in the catalytic behaviour of both systems are reported, using hydrogenation of 1-octene and Z-α-acetamidocinnamic acid as model reactions.
Base catalyzed cyclization of substituted esters of hydantoic and thiohydantoic acids
Authors: Kaválek Jaromír , Macháček Vladimír , Svobodová Gabriela , Štěrba Vojeslav
Published: September 2010

Base catalyzed cyclization rates have been measured of 22 derivatives of hydantoic and thiohydantoic acid esters in water and methanol. The cyclization of methyl and ethyl esters of hydantoic and 5-methylhydantoic acids is accompanied by hydrolysis of the ester group, whereas with the other derivatives the hydrolysis does not take place. Hydrolysis of the cyclization products (hydantoin and thiohydantoin derivatives) is not significant under the kinetic conditions. The cyclization of methyl ester of 5-phenylhydantoic acid in methanol is reversible; the equilibrium mixture contains 30% of the starting ester. In all the cases the cyclization is subject to specific base catalysis; exceptions are esters of 5-phenylthiohydantoic and 5-phenyl-2-methylthiohydantoic acids whose cyclizations are subject to general base catalysis. Substituents always accelerate the cyclization. The 3-substituents have the greatest effects, the cyclization rate being considerably increased with bulk of the substituents; similarly large effect of 5-phenyl group consists mainly in its polar effects on the pre-equilibrium. The cyclization are slower in methanol at the same concentration of the lyate ion: the greatest difference (up to 3 orders of magnitude) is observed with the 5-phenyl derivatives.
Europium and cerium extraction by the nitrobenzene solution of dicarbolide in the presence of polyethylene glycols
Authors: Makrlík Emanuel , Vaňura Petr
Published: September 2010

Extraction of Eu3+ and Ce3+ microamounts from 0.1-0.4M perchloric acid by the nitrobenzene solution of dicarbolide H+[Co(C2B9H11)2]- in the presence of polyethylene glycols (Mr = 200, 300, 400) has been studied. The equilibrium data and the typical maxima on the dependence of the metal distribution ratio on the total analytical concentration of polyethylene glycol in the system can be explained assuming that the species ML3+org, ML3+2org, ML3+3org, MLH2+-1org, and HL+org (where M3+ = Eu3+, Ce3+; L = polyethylene glycol) are extracted into the organic phase. The values of extraction and equilibrium constants in the organic phase were determined and the effect of the polyethylene glycol molecular weight on the equilibrium constants and on the abundances of individual species in the organic phase is discussed. It has been found that the addition of polyethylene glycol to the acid - nitrobezene - dicarbolide system increases the values of the separation factors αCe/Eu.
Effect of the membrane potential on the performance of ultrafiltration membranes
Authors: Schwarz Hans-Hartmut , Kůdela Vlastimil , Lukáš Jaromír , Vacík Jiří , Gröbe Volker
Published: September 2010

In the pressure driven process the performance of membranes for ultrafiltration can be changed by incorporating charged groups into the membranes. sulfonation of polysulfone membranes the membrane potential is varied. On interaction of the negatively charged membrane with positively or negatively charged protein molecules the formation of a concentration polarization gel layer proceeds at different rate. Thus, the performance of the membrane can be controlled by the membrane potential. The dependence of the performance on the potential is discussed and procedures for membrane cleaning are suggested.
Kinetics of acid catalyzed decomposition of substituted 1,3-diphenyl-3-methyltriazenes
Authors: Svoboda Petr , Pytela Oldřich , Večeřa Miroslav
Published: September 2010

Kinetics of the acid catalyzed decomposition of fifteen 1-substituted-1,3-diphenyl-3-methyltriazenes have been studied in 40% aqueous ethanolic buffers at 25 °C. The slope found for the dependence log kobsvs pH of the buffer is not equal to unity, and a method of treating such experimental data is suggested. The reaction constant found (ρ = -3.70) indicates that substituents have similar effects on both protonation and decomposition of the triazene chain.
Isomeric oximes of 30-norlupan-20-one and its derivatives
Authors: Vystrčil Alois , Křeček Václav , Buděšínský Miloš , Protiva Jiří
Published: September 2010

30-Norlupan-20-one (Ib) and its derivatives IIb-Vb were converted into 5 : 1-10 :1 mixtures of relatively stable E and Z oximes Ic,d-Vc,d. Beckmann rearrangement of the oxime mixtures (as obtained from the oximation) afforded isomeric amides VIII-XII and XIII-XVI in the ratios 3.5 : 1 to 5 : 1. Oximes Vc,d with the E-ring bridged by a lactone grouping, react with difficulty and the rearrangement was proved only for the Z-isomer Vd.
Effect of the way of fixing 8-hydroxyquinoline to glycidyl methacrylate gel on the properties of the resulting chelating ion exchanger
Authors: Janák Karel , Janák Jaroslav
Published: September 2010

The practical sorption capacity, rate of establishment of the sorption equilibrium, pH-dependence of the distribution coefficient of Cu2+ ions, sorption isotherm, and stability of the ion exchanger were determined and mutually compared for two different ways of fixation of 8-hydroxyquinoline to glycidyl methacrylate gel (G-gel). The effect of the ion exchanger particle size on some of its properties was also investigated. In the ion exchanger obtained by direct fixation of copper(II) 5-(4-hydroxyphenylazo)-8-quinolinate, the modified reagent retains a steric arrangement suitable for chelation.
Preparation and properties of a styrene-ethylene dimethacrylate copolymer-based chelating ion exchanger with bonded 8-hydroxyquinoline
Authors: Janák Karel , Janák Jaroslav
Published: September 2010

An optimum procedure was sought for the fixation of 8-hydroxyquinoline to styrene-ethylene dimethacrylate copolymer (SE-gel) with respect to the capacity of the resulting ion exchanger. The time of establishment of the sorption equilibrium, pH-dependence of the distribution coefficient of Cu2+ ions, sorption isotherm of Cu2+ ions, and the ion exchanger stability were determined.
The composition of complexes in the organic phase during the extraction of Eu(III) and Am(III) by benzyldibutylamine and benzyltrialkylammonium nitrates
Authors: Kuča Libor , Jedináková Věra , Daňo Lubomír
Published: September 2010

The extraction of americium and europium from acid nitrate solutions by benzene solutions of benzyldibutylamine nitrate (I) and quaternary ammonium salts benzyllauryldimethylammonium nitrate (II) and benzyltrioctylammonium nitrate (III) has been studied. During extraction with I, {(R3NH+)2, Me(NO3)2-5} is formed in the organic phase, extraction with II yields {(R4N+), Me(NO3)-4} and {(R4N+)2, Me(NO3)2-5} is formed during extraction with III. The concentration of nitrate ions does not have an unambiguous effect on the stoichiometry of the extraction. In addition to favouring the formation of the nitrate complexes of Am3+ and Eu3+, which are extracted by amines, nitrate ions also have a nonspecific salting out effect. The changes in the water content in the organic phase in dependence on the concentration of the metal complex suggests that the complex of Eu with II is not hydrated in the organic phase.
Preparation of diamantanedicarboxylic acids with carboxyl groups on one secondary and one tertiary carbon atom
Authors: Vodička Luděk , Burkhard Jiří , Janků Josef
Published: September 2010

Bromination of 3-diamantanecarboxylic acid leads to a mixture of bromodiamantanecarboxylic acids which on Koch-Haaf carboxylation at high dilution affords a mixture of diamantanedicarboxylic acids with one carboxyl on the secondary and the other on the tertiary carbon atom of the diamantane skeleton. At low dilution, the Koch-Haaf carboxylation gives predominantly 3,9-diamantanedicarboxylic acid.
Photosensitized [2 + 2]-cycloaddition of 3-acetyl-2[3H]-oxazolone to maleic anhydride, dimethylmaleic anhydride, and 1,6-anhydro-4-O-benzyl-2,3-dideoxy-β-D-erythro-2-hexenopyranose
Authors: Sekretár Stanislav , Kopecký Jan , Černý Miloslav
Published: September 2010

Acetone-sensitized [2 + 2] photocycloaddition of 2[3H]-oxazolones (I-II) to maleic anhydride and dimethylmaleic anhydride has been used to prepare the corresponding cyclobutane derivatives (III-IV) and (VIII).
Heterocyclic nitrogen-containing compounds from the extract of the springtail Tetrodontophora bielanensis (WAGA)
Authors: Buděšínský Miloš , Trka Antonín , Stránský Karel , Streibl Milan
Published: September 2010

Two pyrido[2,3-b]pyrazines were isolated from the extract of the springtail Tetrodontophora bielanensis (WAGA). Their structure were determined by mass and NMR spectroscopy: 2,3-dimethoxypyrido[2,3-b]pyrazine (I) and 2-methoxy-3-isopropylpyrido[2,3-b]pyrazine (II).
A versatile expert system Seneca in chemical and system engineering
Authors: Dohnal Mirko
Published: September 2010

Mathematical model (statistical, analytical, fuzzy) is certain integration of primary data into a form ensuring simple use and solving the problem under consideration. Any processing of information is an irreversible process. In order that this loss of information may be minimized, an expert system SENECA has been developed. With the aid of algorithms of artificial intelligence this system utilizes directly the primary data in order to solve the given problem. The system has been based on the fuzzy similarity. The versatility of the proposed expert system rests in the fact that in a very simple manner an expert base can be implemented into this system. This base represents a fuzzy description of the primary data, concerning the problem under consideration. The primary data may be represented by laboratory measurements, by results of passive observation of a real equipment, literature data, experience, analogies, etc. The data are therefore very diverse. The approach is demonstrated on a two-dimensional model of a fermentor.
Reactivity of [m]ferrocenophanones: The aldol condensation
Authors: Elečko Pavol , Toma Štefan , Vrúbel Miroslav , Solčániová Eva
Published: September 2010

Investigation of the reaction of [m]ferrocenophanones with p-chlorobenzaldehyde in basic medium showed that these cyclic ketones are much more reactive than their acyclic counterparts. The size of the bridge and the position of the carbonyl group influenced the reaction. Thus, [m]ferrocenophan-1-ones (m =3,4 afforded β-hydroxyketones only, [5]ferrocenophan-1-one gave in addition an α,β-unsaturated ketone, and [4]ferrocenophane-2-one yielded only α,β-unsaturated ketones. Oxidation of [m]ferrocenophanes with MnO2 furnished the expected monoketones and [4]ferrocenophane-1,4-dione and [5[ferrocenophane-1,2-dione. The preparation of [5]ferrocenophane-1,5-dione was also improved.
Reactions of 3-butine-2-methyl-2-ol with isothiocyanates
Authors: Kutschy Peter , Dzurilla Milan , Kniežo Ladislav , Bernát Juraj , Imrich Ján , Kristian Pavol , Nádaskay Róbert
Published: September 2010

3-Butine-2-methyl-2-ol reacts with isothiocyanates in the presence of sodium hydride in dimethylformamide to give various products depending on structure of the isothiocyanate residue. Isothiocyanates with the NCS group bound to sp2 carbon atom (phenyl, 4-bromophenyl, and styryl isothiocyanates) give the respective 1,3-oxazolidine derivatives. If the NCS group is bound to an sp3-hybridized carbon atom (ethyl and benzyl isothiocyanates), derivatives of 1,3-oxathiolane are formed. Acyl isothiocyanates (benzoyl and 3-phenylpropenoyl isothiocyanates) give products of substitution of the NCS group, viz. 1-butine-3-methyl-3-yl benzoate and 3-phenylpropenoic anhydride.
The synthesis of substituted 2H-1,2-benzothiazines 1,1-dioxides
Authors: Svoboda Jiří , Paleček Jaroslav , Dědek Václav
Published: September 2010

The base-catalyzed rearrangement of the esters of 2H-1,2-benzothiazolin-3-one-2-acetate 1,1-dioxide (IIa - IIc) afforded substituted 2H-1,2-benzothiazine-3-carboxylate 1,1-dioxides IIIa -IIIc. After N-alkylation and aminolysis the antiinflammatory drugs piroxicam and isoxicam were obtained.
Binding of calcium, lead, and copper(II) cations to galactaric and 2,5-furandicarboxylic acids and to D-galacturonic acid and its derivatives
Authors: Kohn Rudolf , Hirsch Ján
Published: September 2010

The binding of Ca2+, Pb2+, and Cu2+ ions to galactaric and 2,5-furandicarboxylic acids and of Pb2+ and Cu2+ ions to D-galacturonic acid, its α-methylglycoside, and (methyl-4-deoxy-α-D-galactopyranosid)uronic acid was evaluated in terms of the activity coefficients of the counter-ions and the degrees of their association with the carboxylate groups of the acids. The activity of Ca2+ ions was determined by the metallochromic indicator method with tetramethylmurexide, that of Pb2+ and Cu2+ ions, with ion specific electrodes. Galactaric acid bids 89.5% Ca2+ ions, practically all (99.9%) Pb2+ ions and nearly all (98.6% Cu2+ ions, mostly with the formation of insoluble salts. As little as 7.6% Ca2+, 34.0% Pb2+, and 23.9% Cu2+ were bound to 2,5-furandicarboxylic acid in the form of soluble complexes, and slightly more, 4.1% Ca2+, 43.9% Pb2+, and 38.0% Cu2+, to D-galacturonic acid. The difference in the degrees of binding to galactaric acid and 2,5-furandicarboxylic acid is due to the different flexibility of their molecular skeletons. The activities of Pb2+ and Cu2+ ions in solutions of salts of D-galacturonic acid and its derivatives indicate that the OH group at C(4) of D-galacturonic acid takes part in the complexation. For the Pb2+ complex, the OH group at C(1) of the unsubstituted acid in the β-anomeric form also seems to participate in the complexation; this is not the case with the similar Cu complex.
Alkaline hydrolysis of methyl hydrogen malonate in water-organic solvents
Authors: Grančičová Oľga , Holba Vladislav , Beluská Ľudmila
Published: September 2010

Kinetics of alkaline hydrolysis of methyl hydrogen malonate in water-methanol, water-dioxane, water-tert-butyl alcohol and water-ethylene glycol mixtures was examined. The valuse of the transfer functions of the activated complex δmμ≠ from water to the first two mixed media were calculated from the measured solubilities of tetrabutylammonium hydrogen malonate, the activation Gibbs energies and the known values of transfer functions for tetrabutylammonium and hydroxide ions. Some conclusions concerning the effect of a nonaqueous component of the solvent on solvation of the reactants and the activated complex have been drawn from the experimental data obtained.
Photochemical hydrolysis of some nitrophenyl acetates
Authors: Kuzmič Petr , Pavlíčková Libuše , Souček Milan
Published: September 2010

Nitro substituent exhibits a meta-activating effect on the course of photochemical hydrolysis of phenyl acetates since UV photolysis of isomeric 4- and 3-nitrophenyl acetates in neutral aqueous solution leads to the formation of the corresponding phenols with quantum yields 0.002 and 0.006, respectively; 2-methoxy-4-nitro- and 2-methoxy-5-nitrophenyl acetates showed still greater difference in their photochemical reactivity (Φr 0.002 and 0.129, respectively). Quenching of the photohydrolysis of the latter compound with 2,4-hexadienoic acid indicates the participation of a triplet state with the effective lifetime of 0.15 μs. The photoreaction is accelerated in acidic media which means that one of the early photochemical steps is the protonation of the excited state. No incorporation of 18O into the product molecule was observed after the photolysis of 2-methoxy-5-nitrophenyl acetate in H218O, which is an unambiguous evidence that the photoreaction proceeds as a light-induced hydrolysis of the ester bond.
Preparation of N-methyl-5-nitro-2-pyrrolylvinyl bromide
Authors: Hrabovský Ján , Kováč Jaroslav , Vagáčová Katarína
Published: September 2010

N-Methyl-5-nitro-2-pyrrolylvinyl bromide, an activated vinyl halide, was prepared by bromination of potassium 3-(N-methyl-5-nitro-2-pyrrolyl)-2-propenoate.
Minor sesquiterpenic lactones of Laser trilobum (L) BORKH. species
Authors: Smítalová Zdenka , Buděšínský Miloš , Šaman David , Holub Miroslav
Published: September 2010

Six further sesquiterpenic lactones (V - X) and one phenylpropane derivative (XI) were isolated from the underground parts of Laser trilobum species. The structure, including the relative and absolute configuration, of five hithero undescribed lactones has been elucidated and described by formulae VI - X.
Binding of calcium and lead ions to carboxystarch prepared by action of nitrogen dioxide on native starch and its 2,3-dialdehyde derivatives
Authors: Kohn Rudolf , Tihlárik Karol
Published: September 2010

The binding of calcium and lead ions to carboxy derivatives of starch prepared by allowing nitrogen dioxide to act on native maize starch (procedure A) and on starch 2,3-dialdehyde derivatives of degrees of oxidation DO(d.a.) ≥ 0.94 (procedure B) was studied. The carboxy group content of the samples in the H+ form was 4.6 - 12.1 mmol g-1. The effect of alkaline medium on the stability of the carboxy derivatives and on their ability to bind and exchange cations was examined. The Ca2+ → 2K+ exchange was evaluated in terms of the decrease in the electrostatic free enthalpy Δ(Gel/N)KCa, determined by alkalimetric potentiometric titrations, and the binding of Pb2+ ions was evaluated in terms of the activity of the Pb2+ counter-ions determined in suspensions of Pb salts of the carboxy derivatives by means of an ion specific electrode. The IR and CD spectra revealed that the carboxystarch preparations obtained by procedure A contained, in addition to free carboxy groups, a considerable amount of carbonyl groups. During the conversion of the latter groups to the former, even in a weakly alkaline medium, the carboxy derivatives undergo an appreciable degradation and lose, to a great extent, their ability to bind and exchange cations. Procedure B, on the other hand, leads to highly selective starch and amylose carboxy derivatives, exhibiting a small amount of carbonyl groups and featuring a relative stability towards alkaline medium; their binding capacity is as high as 12 milliequivalents of cations per g of sample.
Production of L-malic acid by immobilized bacterial cells of the genus Brevibacterium
Authors: Černý Jaroslav , Škoda Jan
Published: September 2010

A HPLC procedure was developed permitting an exact and rapid determination of L-malate, fumarate, succinate, and other dicarboxylis acids. The method was used to assay the products of fumarate metabolism in two Brevibacterium strains, obtained by screening, and showing a high fumarate conversion both in the cell suspension and in the immobilized system. Polyacrylamide and Ca-alginate were employed as polymeric matrices. The conditions were determined (pH, temperature, ion concentration, effect of inhibitors and detergents) under which L-malate is predominantly formed from fumarate and the conversion degree is the highest (8.60 mmol of L-malate h/g cells). The dependence of the conversion of various types of the polymeric matrix and the stability of the system in a continuous experimental arrangement were also examined. The results of these experiments will be utilized in L-malate technology.
Prediction of higher inversion energy levels for isocyanamide H2NNC
Authors: Jensen Per , Winnewisser Manfred
Published: September 2010

The lowest inversion energies of the pyramidal molecule isocyanamide H2NNC have been predicted using the semirigid invertor model. The calculation was based on an ab initio inversion potential function which we have refined by fitting it to the experimental data available for H2NNC. It is hoped that the predicted energies will make it possible to assign further transitions of H2NNC.
Infinite-dilution activity coefficients by comparative ebulliometry: A model of ebulliometer and the experimental equipment and procedure
Authors: Dohnal Vladimír , Novotná Marcela
Published: September 2010

The ebulliometric technique for determination of infinite-dilution activity coefficients is examined. A simple mathematical model of ebulliometer is formulated to derive and analyze corrections accounting for the difference between the composition of the ebulliometer charge and that of the equilibrium liquid. Our own experimental equipment employing the comparative ebulliometric setup is described along with the measuring procedure and calibration. Error analysis is carried out identifying major factors limiting the accuracy of the determination.
Cyclovoltammetric study of the homogenous keto-enol equilibrium of dihydroxyfumaric acid in acid and neutral media
Authors: Sazou Dimitra , Karabinas Pantelis , Jannakoudakis Dimitrios
Published: September 2010

The keto-enol equilibrium of dihydroxyfumaric acid (DHF) was investigated in acid and neutral buffer solutions by cyclic voltammetry. The keto-form decreases with increasing pH, so that in neutral region (pH = 6 - 8) the equilibrium is totally shifted to the enol-form of the acid. The thermodynamic constant, Kk, of the equilibrium: enol-DHF ⇄ keto-DHF, was estimated at different pH and temperatures. The thermodynamic parameters ΔG, ΔH, and ΔS of the above equilibrium were also determined in 0.5 M-H2SO4 solution.
The synthesis and structure of silica-supported bis(h5-cyclopentadienyl)dichlorotitanium(IV) complexes
Authors: Reissová Alena , Bastl Zdeněk , Čapka Martin
Published: September 2010

The title complexes have been obtained by functionalization of silica with cyclopentadienylsilanes of the type Rx(CH3)3 - xSi(CH2)nC5H5 (x = 1-3, n = 0, 1, 3), trimethylsilylation of free surface hydroxyl groups, transformation of the bonded cyclopentadienyl group to the cyclopentadienyl anion, followed by coordination of (h5-cyclopentadienyl)trichlorotitanium. The effects of single steps of the above immobilization on texture of the support, the number of free hydroxyl groups, the coverage of the surface by cyclopentadienyl groups and the degree of their utilization in anchoring the titanium complex have been investigated. ESCA study has shown that the above anchoring leads to formation of the silica-supported bis(h5-cyclopentadienyl)dichlorotitanium(IV) complex.
Reactions of 2-aryl-4H-furo[3,2-b]pyrrole derivatives
Authors: Kraľovičová Eva , Krutošíková Alžbeta , Kováč Jaroslav , Dandárová Miloslava
Published: September 2010

Preparation of 4-acetyl-2-arylfuro[3,2-b]pyrroles is described and reactions of 2-aryl-4H-furo[3,2-b]pyrrole and its substituted analogues with dimethyl butinedioate and some further reactions inevitable for the structure determination of compounds prepared were studied.
Components of Libanotis buchtormensis (FISCH.) D.C. fruits
Authors: Očir Gončigirijn , Motl Otakar
Published: September 2010

From the light petroleum extract of Libanotis buchtormensis(Fisch.) D.C. fruits paraffins, terpenic hydrocarbons, coumarins (bergapten, imperatorin, isoimperatorin, bergaptol, osthol, isoaculeatin, mexoticin, xanthotoxin), sesquiterpenic alcohols (nerolidol, bisabolol, eudesmol) and β-sitosterol were isolated.
Ribonucleosides of 3-amino- and 3,5-diaminopyrazole-4-carboxylic acid and their open-chain analogues: Synthesis and reactions
Authors: Spassova Maria K. , Holý Antonín , Masojídková Milena
Published: September 2010

Bis(trimethylsilyl) derivative of ethyl 3-aminopyrazole-4-carboxylate (VI) and tris(trimethylsilyl) derivative of ethyl 3,5-diaminopyrazole-4-carboxylate (VII) on reaction with 2,3,5-tri-O-benzoyl-D-ribofuranolyl chloride and subsequent debenzoylation afforded the respective β-D-ribofuranosyl derivatives VIIIa and Xa. Their alkaline hydrolysis led to 1-(β-D-ribofuranosyl)-3-aminopyrazole-4-carboxylic acid (VIIIc) and 1-(β-D-ribofuranosyl)-3,5-diaminopyrazole-4-carboxylic acid (Xb). The esters VIIIa and Xa were not ammonolyzed under normal conditions. Contrary to nucleosidation of the silyl derivatives VI and VII, sodium salt of ethyl 3-aminopyrazole-4-carboxylate was alkylated with 4-chloromethyl-2,2-dimethyl-1,3-dioxolane (XI) or 5-(p-toluenesulfonyloxy)-1,3-dioxane (XVIIb) to give a mixture of the N-isomeric derivatives XIIIa, XIXa and XIIa, XVIIIa, respectively; sodium salt of the 3,5-diamino derivative V reacted with these synthons under formation of the corresponding compounds XIIIb and XXa. Subsequent alkaline and acid hydrolysis of XIIa and XIIIb gave the open-chain analogs of nucleosides XV and XVI. The N-(1,3-dioxan-5-yl) derivatives XVIIIc and XXa resisted acid hydrolysis, giving rise only to carboxylic acids XVIIIb and XXb.