bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial registration of temporally separated whole breast 3D ultrasound images
Authors: Narayanasamy Ganesh , LeCarpentier Gerald L. , Roubidoux Marilyn , Fowlkes J. Brian , Schott Anne F. , Carson Paul L.
Published: August 2009

The purpose of this study was to evaluate the potential for use of image volume based registration (IVBaR) to aid in measurement of changes in the tumor during chemotherapy of breast cancer. Successful IVBaR could aid in the detection of such changes in response to neoadjuvant chemotherapy and potentially be useful for routine breast cancer screening and diagnosis. IVBaR was employed in a new method of automated estimation of tumor volume in studies following the radiologist identification of the tumor region in the prechemotherapy scan. The authors have also introduced a new semiautomated method for validation of registration based on Doppler ultrasound (U.S.) signals that are independent of the grayscale signals used for registration. This Institutional Review Board approved study was conducted on 10 patients undergoing chemotherapy and 14 patients with a suspicious/unknown mass scheduled to undergo biopsy. Reasonably reproducible mammographic positioning and nearly whole breast U.S. imaging were achieved. The image volume was registered offline with a mutual information cost function and global interpolation based on a thin‐plate spline using MIAMI FUSE© software developed at the University of Michigan. The success and accuracy of registration of the three dimensional (3D) U.S. image volume were measured by means of mean registration error (MRE). IVBaR was successful with MRE of in 9 out of 10 reproducibility automated breast ultrasound (ABU) studies and in 12 out of 17 ABU image pairs collected before, during, or after of chemotherapy. Semiautomated tumor volume estimation was performed on registered image volumes giving mean accuracy compared to the radiologist hand‐segmented tumor volume on seven cases. Doppler studies yielded fractional volume of color pixels in the region surrounding the lesion and its change with changing breast compression. The Doppler study of patients with detectable blood flow included five patients with suspicious masses and three undergoing chemotherapy. Spatial alignment of the 3D blood vessel data from the Doppler studies provided independent measures for the validation of registration. In 15 Doppler image volume pairs scanned with differing breast compression, the mean centerline separation value was , while MRE based on a few identifiable structural points common to the two grayscale image volumes was . Another measure, the overlap ratio of blood vessels, was shown to increase from 0.32 to 0.59 with IVBaR for pairs at various compression levels. These results show that successful registration of ABU scans may be accomplished for comparison and integration of information.
Monte Carlo model for a prototype CT‐compatible, anatomically adaptive, shielded intracavitary brachytherapy applicator for the treatment of cervical cancer
Authors: Price Michael J. , Gifford Kent A. , Horton John L. , Eifel Patricia J. , Gillin Michael T. , Lawyer Ann A. , Mourtada Firas
Published: August 2009

Purpose:

Current, clinically applicable intracavitary brachytherapy applicators that utilize shielded ovoids contain a pair of tungsten‐alloy shields which serve to reduce dose delivered to the rectum and bladder during source afterloading. After applicator insertion, these fixed shields are not necessarily positioned to provide optimal shielding of these critical structures due to variations in patient anatomies. The authors present a dosimetric evaluation of a novel prototype intracavitary brachytherapy ovoid [anatomically adaptive applicator], featuring a single shield whose position can be adjusted with two degrees of freedom: Rotation about and translation along the long axis of the ovoid.

Methods:

The dosimetry of the device for a HDR was characterized using radiochromic film measurements for various shield orientations. A MCNPX Monte Carlo model was developed of the prototype ovoid and integrated with a previously validated model of a v2 mHDR source (Nucletron Co.). The model was validated for three distinct shield orientations using film measurements.

Results:

For the most complex case, 91% of the absolute simulated and measured dose points agreed within 2% or and 96% agreed within 10% or .

Conclusions:

Validation of the Monte Carlo model facilitates future investigations into any dosimetric advantages the use of the may have over the current state of art with respect to optimization and customization of dose delivery as a function of patient anatomical geometries.
Evaluation of high‐energy brachytherapy source electronic disequilibrium and dose from emitted electrons
Authors: Ballester Facundo , Granero Domingo , Pérez‐Calatayud José , Melhus Christopher S. , Rivard Mark J.
Published: August 2009

Purpose:

The region of electronic disequilibrium near photon‐emitting brachytherapy sources of high‐energy radionuclides (, , , and ) and contributions to total dose from emitted electrons were studied using the GEANT4 and PENELOPE Monte Carlo codes.

Methods:

Hypothetical sources with active and capsule materials mimicking those of actual sources but with spherical shape were examined. Dose contributions due to source photons, x rays, and bremsstrahlung; source , Auger electrons, and internal conversion electrons; and water collisional kerma were scored. To determine if conclusions obtained for electronic equilibrium conditions and electron dose contribution to total dose for the representative spherical sources could be applied to actual sources, the mHDR‐v2 source model (Nucletron B.V., Veenendaal, The Netherlands) was simulated for comparison to spherical source results and to published data.

Results:

Electronic equilibrium within 1% is reached for, , , and at distances greater than 7, 3.5, 2, and 1 mm from the source center, respectively, in agreement with other published studies. At 1 mm from the source center, the electron contributions to total dose are 1.9% and 9.4% for and , respectively. Electron emissions become important (i.e., ) within 3.3 mm of and 1.7 mm of sources, yet are negligible over all distances for and . Electronic equilibrium conditions along the transversal source axis for the mHDR‐v2 source are comparable to those of the spherical sources while electron dose to total dose contribution are quite different.

Conclusions:

Electronic equilibrium conditions obtained for spherical sources could be generalized to actual sources while electron contribution to total dose depends strongly on source dimensions, material composition, and electron spectra.
Monte Carlo simulation and patient dosimetry for a kilovoltage cone‐beam CT unit
Authors: Downes P. , Jarvis R. , Radu E. , Kawrakow I. , Spezi E.
Published: August 2009

Purpose:The purpose of this work is to characterize the x‐ray volume imager (XVI), the cone‐beam computed tomography (CBCT) unit mounted on the Elekta Synergy linac, with F1 bowtie filter and to calculate the three‐dimensional dose delivered to patients using volumetric acquisition.

Methods:The XVI is modeled in detail using a new Monte Carlo (MC) code,BEAMPP, under development at the National Research Council Canada. In this investigation, a new component module is developed to accurately model the unit's bowtie filter used in conjunction with the available beam collimators at the clinical energy of. The modeling is compared against percentage depth dose (PDD) and profile measurements. Kilovoltage radiation beams’ phase space files are also analyzed. The authors also describe a method for the absolute dose calibration of the MC model of the CBCT unit when used in a clinical volumetric acquisition mode. Finally, they calculate three‐dimensional patient dose from CBCT image acquisition in three clinical cases of interest: Pelvis, lung, and head and neck.

Results:The agreement between measurement and MC is shown to be very good: Withinfor the PDD and withininside the radiation field for all the collimators with the F1 bowtie filter. A full account of the absolute calibration method is given and dose calculation is validated against ion chamber measurements in different locations of a plastic phantom. Calculations and experiments agree withinor better in both at the center and the periphery of the phantom, with worst agreement of 4.5% at the surface of the phantom and for one specific combination of collimator and filter. Patient dose from CBCT scan reveals that dose to tissue is between 2 andfor a pelvis or a lung full acquisition. For H&N dose to tissue is, with the unit presets used in this work. Dose to bony structures can be two to three times higher than dose to tissue.

Conclusions:The XVI CBCT unit has been fully modeled including the F1 bowtie filter. Absolute dose distribution from the unit has been successfully validated. Full MC patient dose calculation has shown that the three‐dimensional dose distribution from CBCT is complex. Patient dose from CBCT exposure cannot be completely accounted for by using a numerical factor as an estimate of the dose at the center of the body. Furthermore, additional dose to bone should be taken into account when adopting any IGRT strategy and weighed vs the unquestionable benefits of the technique in order to optimize treatment. Full three‐dimensional dose calculation is recommended if patient dose from CBCT is to be integrated in any adaptive planning strategy.
Complete Resequencing of 40 Genomes Reveals Domestication Events and Genes in Silkworm (
Bombyx
)
Authors: Xia Qingyou , Guo Yiran , Zhang Ze , Li Dong , Xuan Zhaoling , Li Zhuo , Dai Fangyin , Li Yingrui , Cheng Daojun , Li Ruiqiang , Cheng Tingcai , Jiang Tao , Becquet Celine , Xu Xun , Liu Chun , Zha Xingfu , Fan Wei , Lin Ying , Shen Yihong , Jiang Lan , Jensen Jeffrey , Hellmann Ines , Tang Si , Zhao Ping , Xu Hanfu , Yu Chang , Zhang Guojie , Li Jun , Cao Jianjun , Liu Shiping , He Ningjia , Zhou Yan , Liu Hui , Zhao Jing , Ye Chen , Du Zhouhe , Pan Guoqing , Zhao Aichun , Shao Haojing , Zeng Wei , Wu Ping , Li Chunfeng , Pan Minhui , Li Jingjing , Yin Xuyang , Li Dawei , Wang Juan , Zheng Huisong , Wang Wen , Zhang Xiuqing , Li Songgang , Yang Huanming , Lu Cheng , Nielsen Rasmus , Zhou Zeyang , Wang Jian , Xiang Zhonghuai , Wang Jun
Published: August 2009

The Taming of the Silkworm

Silkworms,
Bombyx mori
, represent one of the few domesticated insects, having been domesticated over 10,000 years ago.

Xia
et al.

(p.
433
, published online 27 August) sequenced 29 domestic and 11 wild silkworm lines and identified genes that were most likely to be selected during domestication. These genes represent those that enhance silk production, reproduction, and growth. Furthermore, silkworms were probably only domesticated once from a large progenitor population, rather than on multiple occasions, as has been observed for other domesticated animals.
Starvation Protects Germline Stem Cells and Extends Reproductive Longevity in
C. elegans
Authors: Angelo Giana , Van Gilst Marc R.
Published: August 2009

Life Histories to Suit

Nematode worms can profoundly manipulate their life histories in several ways. For example,
Caenorhabditis elegans
has two genders: males and hermaphrodites. Some clues for the evolution of this peculiar mating system have been revealed by

Baldi
et al.

(p.
1002
), who turned females of a related species,
Caenorhabditis remanei
, into hermaphrodites by modifying a gene involved in making sperm and another gene required for activating the spermatids. In most animals, the germ line is fully established during adulthood and a reproductive period is determined, at least in part, by aging of the germ line and the viability of oocytes. The reproductive longevity of hermaphrodite
C. elegans
can be increased at least 15-fold by starvation.
Angelo and Van Gilst
(p.
954
, published online 27 August; see the Perspective by

Ogawa and Sommer

) found that in starved worms, the germline component of the reproductive system is actively killed, with the exception of a small set of preserved stem cells. When the worms are able to feed again, these cells regenerate into an entirely new and functional germ line. But this is not all.

Kim
et al.

(p.
994
, published online 1 October; see the Perspective by

Ogawa and Sommer

) show that subsets of the complex mixture of structurally related molecules in dauer pheromone act via distinct G protein–coupled receptors either to initiate longterm effects on development and physiology by modulating the neuroendocrine axis, or to trigger short-term acute effects on behavior by altering neuronal responses.
Accuracy contours in (nT, λ) space in electrochemical digital simulations
Authors: Britz Dieter , Nielsen Merete F.
Published: August 2009

In finite difference simulations of electrochemical transport problems, it is usually tacitly assumed that λ, the stability factor Dδt/δx2, should be set as high as possible. Here, accuracy contours are shown in (nT, λ) space, where nT is he number of finite difference steps per unit (dimensionless) time. Examples are the Cottrell experiment, simple chronopotentiometry and linear sweep voltammetry (LSV) on a reversible system. The simulation techniques examined include the standard explicit (point- and box-) methods as well as Runge-Kutta, Crank-Nicolson, hopscotch and Saul’yev. For the box method, the two-point current approximation appears to be the most appropriate. A rational algorithm for boundary concentrations with explicit LSV simulations is discussed. In general, the practice of choosing as high a λ value when using the explicit techniques, is confirmed; there are practical limits in all cases.
Effects of Langmuirian adsorption on the potentiostatic response at spherical and planar electrodes
Authors: Alcaraz María-Luisa , Gálvez Jesús
Published: August 2009

Equations for a potentiostatic reaction with an adsorption process following Langmuir’s isotherm have been derived for the expanding sphere with any power law electrode model. This model is very general and includes, among others, the following ones: (a) stationary plane; (b) stationary sphere; (c) expanding plane; and (d) expanding sphere. Characteristics of these solutions and the behavior of the corresponding asymptotic solutions are discussed. A comparison of the results obtained for plane and spherical electrodes has also been performed.
Electrode kinetics of the system V(III)/V(II) in aqueous dimethylsulphoxide
Authors: Kišová Libuše , Reichstädter Libor , Komenda Jaro
Published: August 2009

The rate constants for the reduction of V(III) and oxidation of V(II) were measured on a mercury electrode in water and water-dimethylsulphoxide mixtures. Their dependance on the concentration of DMSO differs from that in mixtures of water with an organic solvent of lower basicity. This can be attributed to the existence of different solvates of vanadium in solutions and to different values of the rate constant for these solvates on the electrode surface at different coverages with the organic component. The influence of DMSO both in the primary solvation sphere and in the electrode double layer on the electrode reaction rate is discussed.
Kinetics and mechanism of the phenylacetylene metathesis polymerization catalyzed with WOCl4/Ph4Sn in benzene
Authors: Vohlídal Jiří , Holländer Andreas , Jančálková Markéta , Sedláček Jan , Sargánková Irena
Published: August 2009

Tungsten oxychloride alone and in combination with Ph4Sn were found to induce a polymerization of phenylacetylene (PhA) totrans-rich poly(phenylacetylene) (PPhA). The binary catalyst has a narrow maximum of the activity at the molar ratio [Ph4Sn]o =y = 2, so that two molecules of Ph4Sn are necessary for a conversion of one molecule of WOCl4 to the most active precursor specie. An identical excess of Ph4Sn acts as a noncompetitive inhibitor (retarder) of the overall polymerization. The order of reaction with respect to catalyst (for y = 2) varies with a concentration of the catalyst. It has value 1 for [WOCl4]o from 0.1 to ca 4 mmol.dm-3 and gradually increases over this concentration limit. Mutual interactions of partially associated growing species, eliminating inhibitive effects of monomer and organotin compounds, are supposed as a reason of this uncommon behaviour. The self inhibitive effect of polymerizing PhA was deduced from the dependence of the initial rate of polymerization on the concentration of PhA. This inhibition takes part most probably in both, the initiation and the propagation. The attempts to determine molecular weights of PPhA by VPO method failed because of a rapid degradation of polymer in diluted solution exposed to atmospheric oxygen.
Cw CO2 laser driven oxidation of some perhalogenocycloalkenes
Authors: Pola Josef , Včelák Jaroslav , Chvátal Zdeněk
Published: August 2009

The title reaction of hexafluorocyclobutene, 1,2-dichloro-3,3,4,4-tetrafluorocyclobutene and decafluorocyclohexene studied at total pressure 13.3 and 16 kPa yield oxalyl halides COX.COX (X = F, Cl) and C2F4 that undergo consecutive reactions to COF2, CO and X2. The oxidation of decafluorocyclohexene is preceded by retro-Diels-Alder decomposition affording hexafluorocyclobutene and C2F4. Two alternative mechanisms for the oxidation of the cyclobutenes are presented, one involving a novel cleavage of intermediary bicyclic dioxetanes. The decomposition of oxalyl fluoride into COF2 and CO is favored over its oxidation.
Polarization and apparent dipole moments of some symmetrical molecules
Authors: Exner Otto , Mach Ivan
Published: August 2009

Polarization and apparent dipole moments of a series of symmetrical molecules were determined by the standard method in three solvents: benzene, p-xylene, and mesitylene. Their explanation by complex formation with solvent applies only in the case of 1,4-dicyanobenzene and 4,4’-dicyanobiphenyl since the apparent orientation polarizations (PO.app) are large and depend strongly on solvent. On the other hand, 1,4-dihalogenbenzenes do not form any complexes and PO.appis virtually zero. 1,4-Dihalogenbicyclo[2,2,2]octanes reveal also considerable PO.app which is attributed mainly to enhanced atomic polarization but – in the case of heavier halogens – also partly to complexes of unknown structure.
Application of the MNDO method in planning the synthesis of Δ2-1,2,3-triazoles
Authors: Juranić Ivan , Husinec Suren , Savić Vladimir , Porter Alexander E. A.
Published: August 2009

A study on the reactivity of several azides and dipolarophiles in [3 + 2]cycloaddition reaction has been carried out and the results analyzed by MNDO calculations. In all cases it can be demonstrated that the reactivity is dependent not on the energy difference between the HOMO of one reactant and LUMO of the other but on the energy difference of corresponding chemically significant Mos.
3-(5-X-2-furyl)-2-cyanoacrylonitriles on reaction with 2-cyanomethylbenzothiazole
Authors: Kada Rudolf , Ilavský Dušan , Goljer Igor , Gahér Peter
Published: August 2009

2-Cyanomethylbenzothiazole reacts with 3-(5-X-2-furyl)-, 3-(2-thienyl)- or 3-(2-pyrrolyl)-2-cyanoacrylonitrile in tetrahydrofuran under catalysis of triethylamine to give 1-(2-benzothiazolyl)-1-cyano-2-heteroarylethylenes as a result of replacement of malonodinitrile by 2-cyanomethylbenzothiazole.
An account of regioselectivity in [2 + 3] cycloaddition of benzonitrile N-oxides with nitroethene by PMO theory
Authors: Barański Andrzej , Bánki Gyula
Published: August 2009

The application of PMO treatment to [2 + 3] cycloaddition of nitroethene to benzonitrile N-oxides is described. It was found that the reaction is under charge transfer control and PMO considerations based on MNDO calculations allow for the elucidation of the observed regioselectivity.
Argon and nitrogen adsorption on graphite at high temperatures
Authors: Bottani Eduardo Jorge , Llanos Jorge Luis , Cascarini de Torre Lydia Ethel
Published: August 2009

Nitrogen and argon adsorption on two graphites differing in their surface homogeneity was studied in a wide range of temperatures (77.5 K up to 183.2 K). The experimentally determined entropy of the adsorbed phase and isoteric heat of adsorption were analyzed. The Hill-de Boer adsorption isotherm was employed to calculate the apparent two-dimensional critical temperature. The behaviour of the adsorbed film was analyzed to explain the influence exerted upon it by temperature and surface homogenity.
Gas flooding of an inclined blade impeller
Authors: Machoň Václav , Fořt Ivan , Antošová Eva , Španihel Bohumil , Kudrna Vladimír
Published: August 2009

The conditions are studied in the paper of flooding the six plane blade impeller with blades inclined at the angle of 45° of relative size d/D = 1/3 and relative distance from the bottom of cylindrical vessel H2/D = 1/3 equipped at the wall with four radial baffles of width b/D = 0.1 at the relative vessel filling H/D = 1. The flooding conditions are determined experimentally from the course of dependence of the power input ratio of gassed and ungassed impeller on the flow rate number of air blown into the liquid phase (water) in the vessel. Theoretically, the conditions of the impeller flooding, when it is no more able to disperse air blown into the charge, are determined from balance of forces in the liquid flow leaving the region of rotating impeller acting on the bubbles of rising gas under the turbulent regime of charge flow. The results of the blade impeller frequency of revolutions determined theoretically at its flooding were found to be in good agreement with the experimentally determined values of the frequency of revolutions investigated obtained in the model equipment with vessel diameter D = 290 mm.
Trypsin entrapped within liposomes. Partition of a low-molecular-mass substrate as the main factor in kinetic control of hydrolysis
Authors: Formelová Jana , Breier Albert , Gemeiner Peter , Kurillová Lubica
Published: August 2009

Trypsin has been entrapped within liposomes prepared from egg yolk phospholipides by the method of controlled dialysis, and the hydrolysis kinetics of Nα-benzoyl-DL-arginine p-nitroaniline catalyzed by the liposome-entrapped trypsin has been studied by monitoring the flux of substrate and product across the liposomal membrane. The partitioning of the substrate and product between liposomal and extraliposomal environment has been found to represent the main factor in the kinetic control of the hydrolysis.
Contribution to the research and development of radiation chambers in steam reforming. Method for projecting primary reformer radiation chamber based on reactor modelling
Authors: Stehlík Petr
Published: August 2009

A method for projecting radiation chamber representing an up-to-date method for projecting reaction furnaces based on modelling is described. The project is divided into a preliminary balance calculation, a method for projecting radiation chamber tube system and a simulation calculation of thermal chemical processes. The applicability of the model is illustrated by means of an example. Also principles for projecting radiation chambers of reforming furnaces as well as application spheres of the model to projecting practice are referred to.
Novel carrier molecules: lipophilic ammonium ylides for membrane transport of metal picrates
Authors: Král Vladimír , Koudelka Juraj , Mohylová Helena , Šaman David
Published: August 2009

The novel artificial carriers have been synthesized by introduction of lipophilic group of pyrrolidinomalonaldehyde and N-imidazolylmalonaldehyde.. These stable dipolar synthetic carriers were used for transport of metal picrates through a liquid membranes. The cation specificity of the transport was determined by the means of atomic absorption spectroscopy. Carrier properties of ylides were compared with N,N-dimethyldodecylamine N-oxide and DB18C6. The formation of complexes of ylides with some inorganic salts by the means of NMR spectroscopy, X-ray and potentiometric measurements of KS have been studied.
Synthesis of some new heterocyclic compounds containing chromene
Authors: Atalla Ahmed A. , Kamal El-Dean Adel M. , Harb Abd El-Fattah A.
Published: August 2009

2-amino-3-cyano-4H-phenyl-benzo[f]chromene (I) was reacted with formamide, acetic anhydride, and ethyl cyanoacetate to produce compounds (II-IV), respectively. Compound IV reacted with HCONH2, POCl3 and P2S5 to produce corresponding pyrimidobenzochromene (V), chloropyridobenzochromene (VI) and mercaptopyridobenzochromene (VII). Compound VII reacted with α-halocompounds to produce corresponding S-alkylated derivatives (VIIIa to VIIIc), and compound (VI) reacted with different amines to produce corresponding alkyl amino-, or aryl aminopyridobenzochromene (IXa-IXc) but in using hydrazine hydrate, pyrazolopyridobenzochromene (X) was obtained.
Substituted 1,2-diaza-7-oxaspiro[4,4]nonen-6-ones; Preparation, NMR spectra, and crystal structure
Authors: Jonas Jaroslav , Głowiak Tadeusz , Žák Zdirad , Trška Petr , Mazal Ctibor
Published: August 2009

Diazomethane adds to substituted 3-methylene-2-(3H)-dihydrofuranones (Ia-Ii) to give the corresponding title dihydropyrazolospirodihydrofuranones (IIa-IIf, IIi,andIIj) or (IIIa, IIIg, and IIIh). NMR spectra of the adducts are discussed in some detail and the crystal structure has been solved for (4R, 5S)-5-benzoyloxy-1,2-diaza-7-oxaspiro[4.4]non-1-en-6-one (IIa).
Lewis acid catalysis of the ene addition of dimethyl oxomalonate and butyl glyoxylate to olefins: Formation of cyclic ethers and lactones
Authors: Achmatowicz Osman , Rozwadowski Jacek , Szechner Barbara , Szymoniak Jan
Published: August 2009

The Lewis acid (SnCl4, TiCl4) catalyzed ene addition of dimethyl oxomalonate and butyl glyoxylate to pent-1-ene and 3-methylbut-1-ene has been investigated. Side reactions have been noted leading variously to the formation of δ-lactones and/or cyclic esters (tetrahydrofurans). The effect on the reaction course of the structure of the substrates has been discussed.
Synthesis of polysubstituted 2,4-dimethylquinolines as potential antimalarial drugs
Authors: Parushev Stoyan , Vlahov Yoncho , Vlahov Radoslav , Nickel Peter , Snatzke Günther
Published: August 2009

A synthetic way for obtaining 6-amino-2,4-dimethylquinoline derivatives from 2,5-dichloraniline by successive ring closure, nitration, aromatic substitution at so activated quinoline ring, followed by reduction of the nitro group to amino group and alkylation of the last is described.
Study of the coordinated system Pb(II)-alanine-alaninate ion
Authors: Rodríguez Placeres Jesús César , Castro Macias Josefa , Lemus Sánchez Mercedes , Borges Miquel Teresa María
Published: August 2009

The polarographic method has been applied to the study of the mixed-coordinated system Pb(II)-alanine-alaninate ion in aqueous medium, I = 1.0 mol l-1 (NaClO4) and 25 ± 0.1°C. The formation of the complexes [PbA]2+ (β10 = 13.2), [PbA2]2+ (β20 = 25), [PbA(A-)]+ (β11 = 1.01 . 105), [Pb(A-)]+ (β01 = 3.76 . 104) and [Pb(A-)2] (β02 = 6.74 . 107) was observed.
Axial dispersion in the liquid phase in a horizontal two-phase tube reactor
Authors: Fialová Marie , Verner Ctirad , Ebner Lothar
Published: August 2009

The characteristics of axial dispersion in the liquid phase were measured for two basic flow regimes in a horizontal two-phase tube reactor. The data obtained indicate that in some flow regions, axial dispersion can be quite significant.
Palladium catalyzed coupling reaction for the synthesis of C-5 aryl and heteroaryl substituted 2’-deoxycytidine
Authors: Hassan Mohamed E.
Published: August 2009

Cytosine nucleosides substituted at C-5 with differently substituted aryls and heteroaryls have been prepared via a palladium catalyzed reaction utilizing 5-chloromercuri or acetoxymercuri nucleosides and haloarenes or heteroarenes.
Synthesis in the group of nuphar alkaloids. VII. An easy access to (-)-nupharamine
Authors: Leniewski Andrzej , Szychowski Jerzy
Published: August 2009

A simple and effective approach to the total synthesis of (-)-nupharamine (I) is presented, which allows to control the stereochemistry at C-3 by epimerization of the ethoxycarbonyl function. The key steps are reductive amination of the respective substituted 1,5-diketone V and enantiomer resolution of piperidine VI using (1S)-(-)-camphanic acid.
Synthesis of N-[(3-substituted phenoxy)alkyl]acetohydroxamic acids, potential inhibitors of the enzyme 5-lipoxygenase
Authors: Svoboda Jiří , Paleček Jaroslav
Published: August 2009

The synthesis of the title compounds starts from methyl (3-subst. phenoxy)alkanoates II which are reduced to the corresponding aldehydes and then transformed to oximes V by reaction with hydroxylamine. Reduction with borane-pyridine complex gives the hydroxylamines VI which on diacetylation and partial deacetylation provide the hydroxamic acids VIII.
Preparation of 2,2-dimethyl-5-R-1,3-dioxane-4,6-dione derivatives
Authors: Prousek Josef
Published: August 2009

Article without abstract
Exploration of the new method for the synthesis of η6-arenetricarbonylchromium complexes. The scope and limitations
Authors: Hrnčiar Peter , Hudeček Milan , Magomedov Gusein K. I. , Toma Štefan
Published: August 2009

A systematic investigation of the recently described method for the synthesis of η6-arenetricarbonylchromium complexes has been performed. The method gives the fair to excellent yields of complexes in a broad range of benzene derivatives and of some benzenoid arenes. Very low yields of products were obtained with benzene, 2-(2-chlorophenyl)-and 2-(3-fluorophenyl)-1,3-dioxolane. The method failed in the case of benzaldehyde, benzoic acid, benzyl chloride, nitrobenzene, thiophenol and chalcone.
Use of inhibited enzyme electrode for estimation of PEA diamine oxidase inhibitors
Authors: Macholán Lumír , Slanina Jiří
Published: August 2009

A biosensor consisting of a Clark type oxygen electrode and immobilized pea diamine oxidase makes it possible amperometrically to quantify, on the basis of an inhibition effect, substrate analogues of the enzyme (aliphatic amino ketones and monoamines, aromatic diamines), some alkaloids (cinchonine, lobeline, norsedamine) and drugs (1-phenylcyclopropylamine, naphazoline). The output current signal of the inhibited bioelectrode is influenced by the thickness of the membrane and its enzyme content as well as by the sort of the substrate and oxygen concentration in the reaction medium. With most of the tested substances, the response time τ90 is 20-100 s and the linear concentration range about 10-6-10-3 mol l-1 can be observed. The inhibitor concentrations causing a change of the initial current by 50% correspond mostly to the published values of inhibition constants for soluble enzyme. The most efficient inhibitor of the pea diamine oxidase is 1,5-diamino-3-pentanone, for which the accuracy of the method was 5.6%, its reproducibility 7.2%, and detection limit 5 . 10-9 mol l-1.
Reactions of ethyl (arylazo)benzoyl acetate with amino substituted azoles
Authors: Deeb Ali
Published: August 2009

Article without abstract
Formation of sodium disulfite in a solid-gas system
Authors: Vobiš Jiří , Mocek Karel , Erdös Emerich
Published: August 2009

The formation of sodium disulfite by the heterogeneous reaction of solid active sodium sulfite with gaseous sulfur dioxide in the presence of water vapour was investigated over the temperature range of 293 to 393 K at SO2. H2O and O2 partial pressures of 1.2-7.4, 1.2-6.4 and 0-11.3 kPa, respectively. The effect of the reaction time was also examined. Kinetic measurements were supplemented with the determination of the equilibrium dissociation pressure of SO2 in contact with sodium sulfite at 373.15 K. The major aim of the work was to establish the optimum conditions for attaining the maximum degree of conversion of the solid reactant to sodium disulfite. The conditions for the formation of virtually pure sodium disulfite were found.
Periodic structures generated by multicomponent diffusion of reactive components
Authors: Kvasnica Jozef
Published: August 2009

The conditions for the formation of periodic concentrations due to multicomponent diffusion of reactive components are found. These relations are expressed in terms of the diffusion coefficients and the parameters of the reaction kinetics.
Conductance studies of some 1:1 electrolytes in acetone + dimethylsulphoxide mixtures at 25 °C
Authors: Syal Vijay K. , Chauhan Suvarcha , Katoch Alok , Chauhan Mohinder S.
Published: August 2009

Precise molar conductances of Bu4NBPh4, Bu4NI, Bu4NNO3, AgNO3, LiNO3, NaBPh4 and KI have been measured in acetone (Ac), dimethylsulphoxide (DMSO) and Ac + DMSO mixtures over the whole solvent composition range at 25°C. The conductance data has been analysed by computer using Shedlovsky conductance equation. Limiting ionic conductances have been calculated by using Gill’s model. Evaluation of solvated radii of Li+, Na+, K+ and Ag+ ions in Ac + DMSO mixtures shows strong preferential solvation for Li+ ion by DMSO. Na+ and Ag+ ions are found to be preferentially solvated by DMSO in Ac-rich region and by Ac in DMSO rich regions. K+, NO3- and I- ions show no preferential solvation in Ac + DMSO mixtures.
Dark and photoinduced interactions between riboflavin and indole auxins
Authors: Miskoski Sandra , García Norman A.
Published: August 2009

Interactions between riboflavin (RF) and indole auxins in the darkness and under conditions of irradiation with visible light were carried out. Dark complexation takes place in buffered (pH 7) aqueous solution. The association constants determined by static fluorescence quenching range from 70 to 150 mol-1 dm3. The complexation is significant at relatively high indole auxin concentrations (above 10-3 mol dm-3). It is governed by an additive effect of charge transfer, known for flavine-indole systems, and of the hydrophobic bond formation. The latter appears in the case of auxins as the driving force of the interaction. No quenching of singlet-excited RF was detected up to indole auxin concentrations of 5 . 10-3 mol dm-3. Under irradiation with visible light a complex mechanism of competitive reactions is operative: both RF and especially the auxins are decomposed by a combination of type I and II photooxidations at indole auxins concentration of 10-4 mol dm-3. The rate constants of the order of 109 mol-1 dm3 s-1 were estimated for the quenching of triplet excited RF by the indoles. For comparative purposes Rose Bengal sensitized photooxidation of a series of indolecarboxylic acids of indole-3-acetic, -propionic and –butyric acid was examined. The rate constants of the photooxidative process, mediated by singelt molecular oxygen, were of the order of 107 mol-1 dm3 s-1 for the auxins. As a result of the interaction, RF is protected against photobleaching and the auxins decompose via a different mechanism, depending on the relative flavin-auxin concentrations.
Stereoselective synthesis of (Z)-7-octadecenyl isovalerate, a sex pheromone of Euproctis similis xanthocampa
Authors: Sharma Madan L. , Verma Sadhana
Published: August 2009

I simple stereoselective synthesis of (Z)-7-octadecen-1-yl isovalerate (I), a sex pheromone of Euproctis similis xanthocampa has been achieved trough an unambiguous route. The isovalerate type of sex pheromones was discovered in Limantxiidase for the first time.
Structural modification and new methods for preparation of ofloxacin analogs
Authors: Rádl Stanislav , Kovářová Lenka , Moural Jaroslav , Bendová Radoslava
Published: August 2009

Reaction of ethyl 2-(2,4-dichloro-5-fluoro-3-nitrobenzoyl)-3-ethoxyacrylate IIb with 2-amino-1-propanol provided corresponding compound IIIb which under alkaline conditions underwent an aromatic denitrocyclization reaction which after alkaline saponification provided 10-chloro-9-fluoro-3-methyl-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid Vd. Treatment of 8-hydroxyquinolone VIII with 3-bromopropyne in the presence of sodium hydrogen carbonate provided methylene derivative VIIb which was saponified into a appropriate acid VIIc. Compound VIIb treated with N-methylpiperazine and then saponified yielded VIIa. Hydrogenation of 3-methylene derivative VIIb provided 3-methyl derivative Va.
Synthesis of 2-(4’-arylaminosulfonylbiphenyl-4-yl)-5-phenyl-1,3,4-oxadiazole
Authors: Kurfürst Antonín , Nádeník Petr
Published: August 2009

Article without abstract
Extraction of promethium complex with 4-benzoyl-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one into Freon 113 and its mixtures with benzene
Authors: Linhart Petr
Published: August 2009

A study of the dependence of distribution of Pm(III) between aqueous phase ( perchlorate medium) and Freon 113 (or a Freon 113-benzene mixture 2 : 1) on pH and pA has shown that the complex PmA3 is extracted into the organic phase with the extraction constant log Kex = -4.35. The stability constant βn of the complex PmA3 has been calculated by the Leden method.
Induction period of the crystallization of silver nitrate solutions in ethylene glycol
Authors: Sláma Ivo
Published: August 2009

The dependence of the induction period of crystallization on supercooling was examined for the silver nitrate-ethylene glycol system over the concentration region of silver nitrate lome fraction of 0 to 0.12. Addition of AgNO3 to ethylene glycol was found to increase considerably the critical induction period of crystallization, although to a lesser extent than Ca(NO3)2, CaCl2, ZnCl2, LiCl and LiNO3 do. The effect of these salts on the critical induction period of crystallization in dimethylsulfoxide, dimethylformamide, dimethylacetamide and methanol was compared in terms of the solvent-rich composition limit of the glass-forming ability. By using the TTT(Time-Temperature-Transformation) theory, it has been deduced that the effect of the salts on the critical induction period of crystallization of ethylene glycol is probably due to the different dependences of viscosity on their concentration in ethylene glyco in the supercooling region.
Macrocyclic Li+-selective diamides
Authors: Hruška Zdeněk , Petránek Jaromír
Published: August 2009

Several macrocyclic diamides of 4,4,5,5-tetramethyl-3,6-dioxaoctanedioic acid with various N-alkyl substituents have been prepared. Selectivity of these compounds was investigated electrochemically in polymeric (PVC) membranes of ion-selective electrodes.
Crystal structure of 1,6-anhydro-1(6)-thio-β-D-glucopyranose S-oxide
Authors: Novotný Jiří , Podlaha Jaroslav , Černý Miloslav
Published: August 2009

The crystals of the title compound are orthorhombic, space group P212121, a = 6.193(1), b = 6.3734(7), c = 38.553(6)Å, Z = 8. The structure was solved by direct methods and refined to R = 0.035 for 1 460 independent reflections. It is composed of two crystallographically independent but chemically almost identical molecules. The structure is stabilized by hydrogen bonding characterized by strong participation of the sulfoxide groups. A comparison with the structure of the thio derivative demonstrates that the exo-sulfoxide oxygen influences very little the overall conformation of the bicyclic skeleton.
Reactions of six-membered heterocyclic β-enaminonitriles with electrophilic reagents
Authors: Zayed Salem E. , Abou Elmaged Eiman I. , Metwally Saud A. , Elnagdi Mohamed H.
Published: August 2009

The nitriles I reacted with acetylacetone and with ethyl acetoacetate to afford 2-amino-3-cyano-4H-pyran derivatives. They reacted further to yield pyranopyridine derivatives. The reaction of V with acetylacetone afforded the pyridinethione VIII. This afforded, reacting with aromatic aldehydes or with cinnamonitriles quinoline derivatives XVII.
Three-dimensional structures of substituted benzylphenyl ethers
Authors: Schneider Bohdan , Huml Karel , Rejholec Václav
Published: August 2009

Forty nine three-dimensional crystal structures of a benzylphenyl ether fragment retrieved from the Cambridge Structural Database were confronted with computed conformational maps of the fragment. Due to the symmetry the number of analyzed fragments rose to 98. When an endocyclic torsion angle of a phenyl ring deviates from 0° the adjacent torsion angle is deformed in opposite direction compensating thus the deviation from planarity. The shape of the fragment is mainly controlled by torsion angles τ1 = C-C-O-CH2, τ2 = C-O-CH2-C, and τ3 = O-CH2-C-C. The attachment of both phenyl rings to the -CH2-O- moiety is not symmetrical and the deformation depends on the value of the τ3 angle. In the crystal, the fragment prefers conformation with τ1 around 0°, τ2 around 180° and with broad bimodal distribution of τ3 around 0° and ±90° despite the fact that energetically equivalent regions exist in the potential energy maps for τ2 values near 60° and 300° and that many crystal structures with τ3 around 0° lie in higher energetical regions than those with τ3 around 90°. Thus a significant difference between the crystal and simulated gas phase conformations was observed supporting the hypothesis that crystals prefer flatter and more storable molecular conformations.
On the bipyridyl formation in reactions of 2-chloropyridine derivatives with potassium amide in liquid ammonia
Authors: Streef Johannis W. , van der Plas Henk C. , Harkema Sybolt
Published: August 2009

In the reaction of 2,6-dichloropyridine and 2,6-dichloro-3-phenylpyridine with potassium amide in liquid ammonia at –70°C, formation of derivatives of 4,4’-bipyridyl and 3,4’-bipyridyl is observed. The 4,4’ coupling products are far in excess to the 3,4’ coupling products. When the reaction is carried out at –70°C in the presence of potassium permanganate, the corresponding 4-aminopyridines are the main products. 2-Chloro-6-phenoxypyridine is very unreactive with this aminating reagent at –70°C as well as –33°C, but in the presence of potassium permanganate at –33°C 4-amino-2-chloro-6-phenoxypyridine is formed in fair yield. The mechanisms of the formation of the bipyridyls and 4-aminopyridines are presented.
Preparation of 7-spiroepoxy and 7,7-disubstituted cephalosporanate 1,1-dioxide from 7-diazocephalosporanate 1,1-dioxide: Reactions of 7-diazocephalosporanate 1,1-dioxide with aldehydes
Authors: Czajkowski David , Phillips Oludotun A. , Reddy Narender A. V. , Spevak Paul , Lix Bruce , Micetich Ronald G. , Maiti Samarendra N.
Published: August 2009

The reactions of tert-butyl-3-acetoxymethyl-3-cephem-7-diazocephalosporanate 1,1-dioxide (I) with acetaldehyde, benzaldehyde, 2-thiophene caboxaldehyde, 3-thiophene carboxaldehyde, 2-furan carboxaldehyde, 3-furan carboxaldehyde and isobutyraldehyde have been studied. Use of boron trifluoride etherate as a catalyst for these reactions was found to accelerate the reactions markedly and to favour the formation of aldehydes rather than the ketones at C-7 position as the carbonyl product. The products obtained from these reactions and the ratios of carbonyl products to epoxides suggest that the R groups of the carbonyl component have profound influence on the reactions.
Synthesis of polymethylene chain-bridged 6-substituted 8-azapurines and related compounds
Authors: Párkányi Cyril , Yuan Hui Liang , Marín-Montes Martha C. , Essoussi Hans T.
Published: August 2009

The synthesis of a series of polymethylene chain-bridged 8-azapurines as potential DNA intercalating agents is described. N,N’-Bis(5-amino-6-chloro-4-pyrimidyl)-1,3-diaminopropane (III), N,N”-bis(5-amino-6chloro-4-pyrimidyl)-1,8-diaminooctane (IV), and N,N’-bis(5-amino-6-chloro-4-pyrimidyl)-1,12-diaminododecane (V) were synthesized from 5-amino-4,6-dichloropyrimidine (I) and 1,3-diaminopropane (II, n = 3), 1,8-diaminooctane (II, n = 8), and 1,12-diaminododecane (II, n = 12), respectively, as the starting materials. 1,3-Bis(6-chloro-9-purinyl)propane (VI), 1,8-bis(6-chloro-9-purinyl)octane (VII), and 1,12-bis(6-chloro-9-purinyl)dodecane (VIII) were prepared by acid-catalyzed reaction of the corresponding pyrimidines III-V with triethyl orthoformate in N,N-dimethylacetamide. The polymethylene chain-bridged 6-hydroxy-8-azapurines XII-XIV were obtained via diazotization of the corresponding pyrimidines. The spectral data and other physical properties of the new compounds have been determined.
Some reactions of N-propadienyl-4-quinolones
Authors: Rádl Stanislav , Kovářová Lenka
Published: August 2009

N-Alkylation of ethyl 6,7,8-trifluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate (Vg) with 3-bromopropyne followed by acidic hydrolysis provided N-propyl derivative Ic which in alkaline media yielded N-propadienyl derivative IId. Propadienyl derivatives IIa and IIb treated with primary or secondary amines provided intermediates IIIa-IIIc which were hydrolyzed to N-acetonyl derivatives IVa and IVb, respectively. N-Benzylation of ethyl 7-chloro-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate (Va) followed by hydrolysis yielded 1-benzyl-7-chloro-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (Vd) which upon a treatment with N-methylpiperazine provided Ve. Compound Ve was hydrogenated on Pd to 6-fluoro-1,4-dihydro-7-(4-methyl-1-piperazinyl)-4-oxoquinoline-3-carboxylic acid (Vf).
Synthesis of some 1-alkyl-1,4-dihydro-4-oxo-1,7-naphthyridine-3-carboxylic acids
Authors: Rádl Stanislav , Hradil Pavel
Published: August 2009

Reaction of substituted 2-aminopyridines IIIa, IIIb, IIIe, and IIIf with ethyl ethoxymethylene malonate provided corresponding pyridylaminomethylenemalonates Va-Vd, respectively. Thermal cyclization of Va, Vc, and Vd yielded substituted ethyl 4-hydroxy-1,7-naphthyridine-3-carboxylates VIa, VIc, and VId. Compounds VIc and VId treated with morpholine gave 8-morpholino derivatives VIe and VIf. These compounds were ethylated to mixtures of N-ethylated (VIIa, VIIb) and O-ethylated products (VIIIa, VIIIb). Compound VIIIb was also prepared from ethyl 4-chloro-6-fluoro-8-morpholino-1,7-naphthyridine-3-carboxylate VIIIc and sodium ethanolate. Esters VIIa and VIIb were hydrolyzed under acidic conditions to the respective acids VIIc and VIId.
Herbicidal activity of 5-haloimidazo[2,1-b]thiazoles
Authors: Andreani Aldo , Rambaldi Mirella , Locatelli Alessandra
Published: August 2009

A series of 5-haloimidazo[2,1-b]thiazoles, related to 5-bromo-6-phenylimidazo[2,1-b]thiazole XIII,was prepared and tested for their herbicidal activity against seven species of plants.
Reaction of 4-aroyl-2(3H)-dihydrofuranones with hydroxylamine hydrochloride. Synthesis and pharmacological study of a series of 3-aryl-4,5-dihydro-4-isoxazoleacetic acids
Authors: Curzu Maria M. , Pinna Gérard A. , Cignarella Giorgio , Barlocco Daniela , Demontis Maria Piera
Published: August 2009

We have synthesized and tested for their antiinflammatory activity a new series of 3-aryl-4,5-dihydro-4-isoxazoleacetic acids (IVa-IVg). Preliminary pharmacological results seem to indicate the 3-phenyl derivative IVa as the most interesting compound. In fact, when tested against carrageenin edema in Wistar rats, it shows antiinflammatory activity comparable to that of naproxene, taken as reference drug, though of shorter duration. All the substituted phenyl derivatives were less active (IVd-IVf) or inactive (IVb, IVc, IVg).
Theoretical interpretation of retention data of polychlorinated biphenyls in liquid chromatography
Authors: Jakuš Vladimír , Miertuš Stanislav
Published: August 2009

The new approach to the theoretical evaluation of Gibbs free energy of solvation is applied to the estimation of retention data in RP-HPLC. Simple models of stationary and mobile phases in RP-HPLC are used. The correlation between retention data of a series of 15 polychlorinated biphenyls (measured on chemically bonded stationary phase with C18 alkyl chains) and the contribution of the Gibbs solvation energy is investigated in order to determine the dominant factor controlling retention. The retention in RP-HPLC can be predicted on the basis of our thermodynamic retention model. This approach is suitable especially when no standards are available for some derivatives (e.g. metabolites of biologically active substances) and when the interpretation of experimental elution is not clear.