bluuebunny/crossref_metadata_2025 huggingface dataset:
Gluconobacter
as Well as
Asaia
Species, Newly Emerging Opportunistic Human Pathogens among Acetic Acid Bacteria
Authors: Alauzet Corentine , Teyssier Corinne , Jumas-Bilak Estelle , Gouby Anne , Chiron Raphael , Rabaud Christian , Counil François , Lozniewski Alain , Marchandin Hélène
Published: September 2010

Acetic acid bacteria (AAB) are broadly used in industrial food processing. Among them, members of the genera
Asaia
,
Acetobacter
, and
Granulibacter
were recently reported to be human opportunistic pathogens. We isolated AAB from clinical samples from three patients and describe here the clinical and bacteriological features of these cases. We report for the first time (i) the isolation of a
Gluconobacter
sp. from human clinical samples; (ii) the successive isolation of different AAB, i.e., an
Asaia
sp. and two unrelated
Gluconobacter
spp., from a cystic fibrosis patient; and (iii) persistent colonization of the respiratory tract by a
Gluconobacter
sp. in this patient. We reviewed the main clinical features associated with AAB isolation identified in the 10 documented reports currently available in the literature. Albeit rare, infections as well as colonization with AAB are increasingly reported in patients with underlying chronic diseases and/or indwelling devices. Clinicians as well as medical microbiologists should be aware of these unusual opportunistic pathogens, which are difficult to detect during standard medical microbiological investigations and which are multiresistant to antimicrobial agents. Molecular methods are required for identification of genera of AAB, but the results may remain inconclusive for identification to the species level.
Molecular Evidence of Cholera Outbreak Caused by a Toxigenic
Vibrio cholerae
O1 El Tor Variant Strain in Kelantan, Malaysia
Authors: Ang Geik Yong , Yu Choo Yee , Balqis Kamarudin , Elina Husni Tan , Azura Hussin , Hani Mat Hussin , Yean Chan Yean
Published: September 2010

A total of 20
Vibrio cholerae
isolates were recovered for investigation from a cholera outbreak in Kelantan, Malaysia, that occurred between November and December 2009. All isolates were biochemically characterized as
V. cholerae
serogroup O1 Ogawa of the El Tor biotype. They were found to be resistant to multiple antibiotics, including tetracycline, erythromycin, sulfamethoxazole-trimethoprim, streptomycin, penicillin G, and polymyxin B, with 35% of the isolates being resistant to ampicillin. All isolates were sensitive to ciprofloxacin, norfloxacin, chloramphenicol, gentamicin, and kanamycin. Multiplex PCR analysis confirmed the biochemical identification and revealed the presence of virulence genes,
viz
.,
ace
,
zot
, and
ctxA
, in all of the isolates. Interestingly, the sequencing of the
ctxB
gene showed that the outbreak strain harbored the classical cholera toxin gene and therefore belongs to the newly assigned El Tor variant biotype. Clonal analysis by pulsed-field gel electrophoresis demonstrated that a single clone of a
V. cholerae
strain was responsible for this outbreak. Thus, we present the first molecular evidence that the toxigenic
V. cholerae
O1 El Tor variant has invaded Malaysia, highlighting the need for continuous monitoring to facilitate early interventions against any potential epidemic by this biotype.
Bacterial 16S Sequence Analysis of Severe Caries in Young Permanent Teeth
Authors: Gross Erin L. , Leys Eugene J. , Gasparovich Stephen R. , Firestone Noah D. , Schwartzbaum Judith A. , Janies Daniel A. , Asnani Kashmira , Griffen Ann L.
Published: September 2010

Previous studies have confirmed the association of the acid producers
Streptococcus mutans
and
Lactobacillus
spp. with childhood caries, but they also suggested these microorganisms are not sufficient to explain all cases of caries. In addition, health-associated bacterial community profiles are not well understood, including the importance of base production and acid catabolism in pH homeostasis. The bacterial community composition in health and in severe caries of the young permanent dentition was compared using Sanger sequencing of the ribosomal 16S rRNA genes.
Lactobacillus
species were dominant in severe caries, and levels rose significantly as caries progressed from initial to deep lesions.
S. mutans
was often observed at high levels in the early stages of caries but also in some healthy subjects and was not statistically significantly associated with caries progression in the overall model.
Lactobacillus
or
S. mutans
was found either at low levels or not present in several samples. Other potential acid producers observed at high levels in these subjects included strains of
Selenomonas
,
Neisseria
, and
Streptococcus mitis. Propionibacterium
FMA5 was significantly associated with caries progression but was not found at high levels. An overall loss of community diversity occurred as caries progressed, and species that significantly decreased included the
Streptococcus mitis
-
S. pneumoniae-S. infantis
group,
Corynebacterium matruchotii
,
Streptococcus gordonii
,
Streptococcus cristatus
,
Capnocytophaga gingivalis
,
Eubacterium
IR009,
Campylobacter rectus
, and
Lachnospiraceae
sp. C1. The relationship of acid-base metabolism to 16S rRNA gene-based species assignments appears to be complex, and metagenomic approaches that would allow functional profiling of entire genomes will be helpful in elucidating the microbial pathogenesis of caries.
Pseudo-Outbreak of Adenovirus Infection in a Neonatal Intensive Care Unit Due to a False-Positive Antigen Detection Test
Authors: Faden Howard , Ramani Rama , Lamson Daryl , St. George Kirsten
Published: September 2010

Twenty-eight of 56 infants in a neonatal intensive care unit had stools positive for adenovirus by the Sure-Vue adenovirus test. Virus cultures of conventionally processed and chloroform-extracted stool samples, as well as conventional and real-time PCR tests, were negative for adenovirus. The cause for the 50% false-positive rate with the antigen test was not determined.
Novel Use of Tryptose Sulfite Cycloserine Egg Yolk Agar for Isolation of
Clostridium perfringens
during an Outbreak of Necrotizing Enterocolitis in a Neonatal Unit
Authors: Kotsanas Despina , Carson Jolene A. , Awad Milena M. , Lyras Dena , Rood Julian I. , Jenkin Grant A. , Stuart Rhonda L. , Korman Tony M.
Published: September 2010

Clostridium perfringens
has been associated with necrotizing enterocolitis (NEC), which is a serious disease of neonates. Our study describes the novel use of selective tryptose sulfite cycloserine with egg yolk agar (TSC-EYA) during a nursery outbreak. This medium provides a rapid, sensitive, and accurate presumptive identification of
C. perfringens
.
Rhesus Rhadinovirus Infection of Rhesus Fibroblasts Occurs through Clathrin-Mediated Endocytosis
Authors: Zhang Wei , Zhou Fuchun , Greene Whitney , Gao Shou-Jiang
Published: September 2010

Rhesus rhadinovirus (RRV) is a gammaherpesvirus closely related to Kaposi's sarcoma-associated herpesvirus (KSHV), an oncogenic virus linked to the development of Kaposi's sarcoma and several other lymphoproliferative diseases, including primary effusion lymphoma and multicentric Castleman's disease. RRV naturally infects rhesus macaques and induces lymphoproliferative diseases under experimental conditions, making it an excellent model for the study of KSHV. Unlike KSHV, which grows poorly in cell culture, RRV replicates efficiently in rhesus fibroblasts (RFs). In this study, we have characterized the entry pathway of RRV in RFs. Using a luciferase-expressing recombinant RRV (RRV-luciferase), we show that the infectivity of RRV is reduced by inhibitors of endosomal acidification. RRV infectivity is also reduced by inhibitors of clathrin-mediated but not caveola-mediated endocytosis, indicating that RRV enters into RFs via clathrin-mediated endocytosis. Using a red fluorescent protein (RFP)-expressing recombinant RRV (RRV-RFP), we show that RRV particles are colocalized with markers of endocytosis (early endosome antigen 1) and clathrin-mediated endocytosis (clathrin heavy chain) during entry into RFs. RRV particles are also colocalized with transferrin, which enters cells by clathrin-mediated endocytosis, but not with cholera toxin B, which enters cells by caveola-mediated endocytosis. Inhibition of clathrin-mediated endocytosis with a dominant-negative construct of EPS15, an essential component of clathrin-coated pits, blocked the entry of RRV into RFs. Together, these results indicate that RRV entry into RFs is mediated by clathrin-mediated endocytosis.
Herpes Simplex Virus Glycoprotein D Interferes with Binding of Herpesvirus Entry Mediator to Its Ligands through Downregulation and Direct Competition
Authors: Stiles Katie M. , Whitbeck J. Charles , Lou Huan , Cohen Gary H. , Eisenberg Roselyn J. , Krummenacher Claude
Published: September 2010

To initiate membrane fusion and virus entry, herpes simplex virus (HSV) gD binds to a cellular receptor such as herpesvirus entry mediator (HVEM). HVEM is a tumor necrosis factor (TNF) receptor family member with four natural ligands that either stimulate (LIGHT and LTα) or inhibit (BTLA and CD160) T cell function. We hypothesized that the interaction of gD with HVEM affects the binding of natural ligands, thereby modulating the immune response during infection. Here, we investigated the effect that gD has on the interaction of HVEM with its natural ligands. First, HSV gD on virions or cells downregulates HVEM from the cell surface. Similarly,trans-interaction with BTLA or LIGHT also downregulates HVEM from the cell surface, suggesting that HSV may subvert a natural mechanism for regulating HVEM activity. Second, we showed that wild-type gD had the lowest affinity for HVEM compared with the four natural ligands. Moreover, gD directly competed for binding to HVEM with BTLA but not LTα or LIGHT, indicating the possibility that gD selectively controls HVEM signals. On the other hand, natural ligands influence the use of HVEM by HSV. For instance, soluble BTLA, LTα, and LIGHT inhibited the binding of wild-type gD to HVEM, and soluble BTLA and LTα blocked HSV infection of HVEM-expressing cells. Thus, gD is at the center of the interplay between HVEM and its ligands. It can interfere with HVEM function in two ways, by competing with the natural ligands and by downregulating HVEM from the cell surface.
Pseudorevertants of a Semliki Forest Virus Fusion-Blocking Mutation Reveal a Critical Interchain Interaction in the Core Trimer
Authors: Liu Catherine Y. , Besanceney Christen , Song Yifan , Kielian Margaret
Published: September 2010

Semliki Forest virus (SFV) is an enveloped alphavirus that infects cells by a low-pH-triggered membrane fusion reaction mediated by the viral E1 protein. E1 inserts into target membranes and refolds to a hairpin-like homotrimer containing a central core trimer and an outer layer composed of domain III and the juxtamembrane stem region. The key residues involved in mediating E1 trimerization are not well understood. We recently showed that aspartate 188 in the interface of the core trimer plays a critical role. Substitution with lysine (D188K) blocks formation of the core trimer and E1 trimerization and strongly inhibits virus fusion and infection. Here, we have isolated and characterized revertants that rescued the fusion and growth defects of D188K. These revertants included pseudorevertants containing acidic or polar neutral residues at E1 position 188 and a second-site revertant containing an E1 K176T mutation. Computational analysis using multiconformation continuum electrostatics revealed an important interaction bridging D188 of one chain with K176 of the adjacent chain in the core trimer. E1 K176 is completely conserved among the alphaviruses, and mutations of K176 to threonine (K176T) or isoleucine (K176I) produced similar fusion phenotypes as D188 mutants. Together, our data support a model in which a ring of three salt bridges formed by D188 and K176 stabilize the core trimer, a key intermediate of the alphavirus fusion protein.
The DAN method for calculation of vapour-liquid equilibria using an equation of state; Flash calculation
Authors: Novák Josef P. , Růžička Vlastimil , Malijevský Anatol , Matouš Jaroslav , Linek Jan
Published: September 2010

A modification of the computational technique for flash calculations using an equation of state has been developed. The procedure consists in the double application of the Newton-Raphson method (DAN) to the set of equilibrium conditions. The algorithm is designed to minimize the number of iterations. It is, therefore, especially useful in successive calculations, where a family of solutions at slightly changing conditions is desired.
Adsorptive stripping voltammetric determination of butanthiol and cyclohexanthiol
Authors: Stará Věra , Kopanica Miloslav
Published: September 2010

1-Butanthiol and cyclohexanthiol is determined by cathodic stripping voltammetry with adsorptive accumulation of the formed mercury salts of the thiols on the surface of the hanging mercury drop electrode. Butanthiol can be determined in the concentration range from 9.0 μg l-1 to 1.8 mg l-1, cyclohexanthiol in the range from 90 μg l-1 to 2.5 mg l-1. The method can be applied for the analysis of poluted air, after trapping the thiol in ammonium hydroxide-methyl alcohol mixture. Sulphides do not interfere with the determination.
Competitive hydrogenation of unsaturated hydrocarbons on palladium catalysts modified with lead and thallium
Authors: Červený Libor , Paseka Ivo , Surma Karel , Thanh Nguyen Thi , Růžička Vlastimil
Published: September 2010

The competitive catalytic hydrogenations of pairs of 2,5-dimethyl-2,4-hexadiene with 1-heptene and 2-octyne with 1-heptene were studied on palladium black modified with lead or thallium to various degrees of coverage. The dissolved and adsorbed hydrogen was determined electrochemically and the selectivities of the competitive hydrogenations were established. The effect of the lead or thallium ad-atoms on the hydrogenation kinetics is discussed.
Constituents of the liverwort Bazzania trilobata of Czech origin
Authors: Konečný Karel , Streibl Milan , Vašíčková Soňa , Buděšínský Miloš , Šaman David , Ubik Karel , Herout Vlastimil
Published: September 2010

From Bazzania trilobata of Czech origin a series of sesquiterpenoids were obtained as products identical with those described in a recent paper from the same species of Japanese origin, namely α- and β-barbatene, bazzanene, cuparene, calamenene, 5-hydroxy- and 7-hydroxycalamenene, and drimenol. Furthermore we obtained ledene, gymnomitrol, gymnomitrone and viridiflorol as new components for this plant. A detailed study of the wax components was performed, too. A study of seasonal variations of the essential oil content and of its composition is presented.
Synthesis of new branched polypeptides with poly(lysine)back bone
Authors: Hudecz Ferenc , Szekerke Mária
Published: September 2010

New analogues of branched polypeptides were synthesised for a further, more detailed study of the influence of the side chain terminating amino acids, particularly the hydrophobic character, configuration and the number of these amino acids, on the conformation and biological properties of the polymers. The following amino acids were coupled to poly(L-Lys-(DL-Alam)) in suitably protected and activated forms to study the above mentioned aspects: L-Nlc, L-Ile, L-Val, L-Phe, D-Phe, D-Leu, D-Tyr, D-His, L-Glu, D-Glu, L-Lys, D-Lys and additionally the L-Glu-L-Glu, D-Glu-D-Glu, L-Lys-L-Lys and D-Lys-D-Lys dipeptides. The deprotected and purified end products were freezedried and characterized by various methods.
Liquid-liquid equilibrium of ternary systems water-glycol-aromatic hydrocarbon
Authors: Lešek František , Eichler Josef , Balcar Miroslav
Published: September 2010

By using the method of determining cloud point, the liquid-liquid equilibria of the systems water-1,2-propanediol-toluene, water-1,2-propanediol-xylene, water-1,3-butanediol-toluene and water-1,3-butanediol-xylene were measured within the range of 40 °C up to azeotropic points at atmospheric pressure. The solubility of the hydrocarbons w3 in the glycols has increased with temperature t according to the relation w3 = (A-Bt)-1, where A and B have been functions of water content in the glycols. The solubility of the water(l)-glycol(2) binary system in the hydrocarbons has increased with temperature according to the relation (w1 + w2) = C exp (Dt). The decrease of mutual solubilities of toluene or xylene in aqueous 1,2-propanediol or 1,3-butanediol was found experimentally to be proportional to the increasing content of water in glycols.
A kinetic study of oxidation of 1,2-diols with periodic acid by means of currentless E-t curves
Authors: Dlask Vladimír
Published: September 2010

The oxidations of ethanediol, 1,2-propanediol, and 1,2-cyclohexanediol with periodic acid have been followed on various electrodes by means of the currentless potential-time curves, and the rate constant values found have been compared with the results obtained by the polarographical method.
The crystal structure of potassium ΛΔ-rac-2,3-butanediamine-N,N,N',N'-tetraacetatecobaltate hemihydrate
Authors: Kalina Marián , Kettmann Viktor , Pavelčík František , Majer Jaroslav
Published: September 2010

The crystal structure of ΛΔ-K [Co(rac-bdta)] . 1/2 H2O was solved by the X-ray diffraction method and refined by the least squares method to R = 0.047 on the basis of 3 847 diffraction values. The substance crystallizes in a space group with symmetry P 1 with the following lattice parameters: a = 0.9412(5), b = 1.2166(6), c = l.5370(9)nm, α = 70.68(4), β = 73.45(4), γ = 83.24(4)°. The crystal structure consists of two symmetrically independent enantiomer pairs Δ-[Co(R,R)-bdta] and Λ-[Co(S,S)-bdta]- K+ ions and molecules of water of crystallization. The Co(III) atom is octahedrally coordinated by rac(bdta)4- forming four glycine and one ethylenediamine chelate ring. The stereospecific coordination of rac(bdta)4- is based on an energy preference for equatorially located methyl groups on the central ethylenediamine ring. Two types of strain in the [Co(rac-bdta)]- complex are derived from the three five-membered rings in the equatorial plane of the complex and repulsion between the methyl and methylene hydrogen atoms.
Principle of additivity of dipole moments: 1,3- and 1,3,5-derivatives of benzene
Authors: Koudelka Juraj , Exner Otto
Published: September 2010

Dipole moments of fourteen 1,3-derivatives and thirteen 1,3,5-derivatives of benzene, with axially symmetrical substituents only, were measured in two solvents. After excluding the compounds forming the donor-acceptor complexes with benzene, the experimental values are well reproduced by the vector addition of group moments, i.e. the accuracy achieved is sufficient for practical purposes. Nevertheless, small systematic deviations were observed: the experimental moments were as a rule less than additive in the case of 1,3-derivatives but greater in the case of 1,3,5-derivatives. These deviations cannot be accounted for by deformation of bond angles from the hexagonal geometry but they can be semiquantitatively interpreted by mutual inductive interaction of dipoles. The latter interpretation was supported by CNDO/2 calculations.
Principle of additivity of dipole moments: Halogen derivatives of adamantane
Authors: Exner Otto , Koudelka Juraj
Published: September 2010

Dipole moments of halogenated adamantanes II-IV were measured in two solvents using the Guggenheim-Smith method. The reliability of the method was checked on non-polar symmetrical compounds I, V. The dipole moments of 1,3-dihalogen and 1,3,5-trihalogen derivatives reveal small but real deviations from the additive behaviour: the experimental values are less than those calculated by vector addition from the moments of monoderivatives, assuming tetrahedral geometry. This fact can be explained by mutual induction of dipole rather than by angle deformation, although both effects can contribute. The deviations from the additive behaviour are qualitatively represented by CNDO/2 calculations with fixed geometry. However, even the greatest deviations observed amount only several percent in relative values and do not impair the general applicability of the bond moment approach.
Laser driven pyrolysis of n-alkanes
Authors: Pola Josef , Chvalovský Václav
Published: September 2010

CW CO2 laser photosensitized (SF6) homogeneous pyrolysis of n-alkanes (C5-C7) affords almost twice higher yield of important ethylene compared to conventional pyrolysis in tubular reactors. No production of heavy pyrolytic oils, resins or coke and very small alteration of the pyrolytic distribution with the conversion are other advantages of the laser process that can be ascribed to the absence of in conventional reactors important surface reactions.
Parity of Kekulé structures revisited
Authors: Křivka Pavel , Trinajstić Nenad
Published: September 2010

A generalized definition of the parity of Kekulé structures is proposed.
Formation of salts of heteropolyacids in nitrate melts
Authors: Drátovský Milan , Havlíček David
Published: September 2010

The acid-base reaction between Na2MoO4 + Na4As2O7 as Lux bases dissolved in an NaNO3 + KNO3 melt and an NO2 + O2 gas mixture as a Lux acid gave a novel heteropolyacid salt whose composition is approximately (Na, K)18As2Mo17O65, (Na, K)16As2Mo18O56, (Na, K)16As2Mo17O64. This compound can also be obtained by direct fusion of the components (Na4As2O7, Na2MoO4 and MoO3) over the temperature region of 420-600 °C. Based on the study of the arsenate and diarsenate ions in a nitrate melt and the molecular spectra of the compound obtained it is suggested that the basic unit of the heteropolyanion structure is the diarsenate anion. The formation of analogous compounds can generally be expected for X/Z combinations with X = P(V), As(V), V(V) and Z = Mo(VI), W(VI).
α-Trichloromethylsulfonyl-5-nitro-2-furaldehydes, a new type of SH-group uncouplers and intermediates in the synthesis of 5-nitro-2-furylarylnitrilimines
Authors: Jurášek Adolf , Kováč Jaroslav , Palovčík Radoslav , Mazag Ľuboš
Published: September 2010

Trichloromethylsulfonyl-5-nitro-2-furaldehyde 4-X-phenylhydrazones I (X = H, CH3, Cl, CN, NO2, COOC2H5) were obtained by reacting 4-X-phenyldiazonium salts with 5-nitrofurfuryltrichloromethyl sulfone. These compounds react with diazomethane and trimethylamine to give the corresponding N-methylated derivatives and nitrilimines, respectively, the latter under elimination of trichlorosulfinic acid. The hydrazone-diaziridine tautomerism was studied by 1H, 15N, and 13C NMR methods; also the IR and UV spectra of the compounds synthesized are discussed. All hydrazones showed a very strong effect on the stimulation of mitochondria respiration and constitute a new type of SH-group uncouplers acting already in a 10-8 mol l-1 concentration.
Mechanism of acetoacetylation of substituted anilines
Authors: Knížek Jiří , Lejdar Erhard , Vetešník Pavel
Published: September 2010

Kinetics have been studied of the reaction of diketene with substituted anilines, and the reaction rate has been found to depend on relative permittivity of the system. The rate and equilibrium constants have been calculated by combination of rate and equilibrium relations with the relation by Amis; the constants correlate with the Hammett substituent constants. The reaction does not proceed as a simple bimolecular process. A reaction mechanism has been suggested.
Structure characterization of reaction products from phenylhydrazonopropanedinitrile and thiols
Authors: Sulo Pavol , Šturdík Ernest , Liptaj Tibor , Jakubík Tibor , Antalík Marián
Published: September 2010

Phenylhydrazonopropanedinitriles react with thiols (benzyl mercaptan, cysteine, 2-mercaptoethanol, mercaptoacetic acid, glutathione, and alcohol dehydrogenase) to give addition products in which thiolate anion is attached to electrophilic carbon atom of cyano group. The reaction ability and way of reaction of phenylhydrazonopropanedinitriles are discussed in the context of mechanism of biological activity of these compounds, particularly that of their uncoupling effect on oxidative phosphorylation.
Identification of gross errors in balance measurements
Authors: Madron František
Published: September 2010

Methods so far proposed for identifying gross error sources in making a one-component mass balance are compared for their effectiveness and the work load involved. Causes of failure of some of the methods are discussed. An approach in which arrangement of normalized adjustments is coupled with successive elimination of measured quantities is recommended as the preferred method.
A study of reactions of 5-substituted furfurylidene derivatives with secondary amines
Authors: Špirková Katarína , Kada Rudolf , Kováč Jaroslav , Knoppová Viera , Dzuroška Miroslav , Margušová Margita
Published: September 2010

The paper describes preparation of 5-bromo-, 5-nitro-, 5-phenylsulphonyl-, and 5-phenylthio-2-furfurylidene derivatives and investigation of their reactions with N-phenylpiperazine, morpholine, piperidine, and pyrrolidine. Kinetics of the reactions have been followed, and UV, IR, and 1H NMR spectra of the compounds produced are interpreted.
Synthesis of spiro(piperidine-4,6'-dibenz[b,e]-1,4-oxathiepin) and its 1-methyl derivative as potential antidepressant agents
Authors: Šindelář Karel , Holubek Jiří , Schlanger Jiří , Dlabač Antonín , Valchář Martin , Protiva Miroslav
Published: September 2010

Starting from 2-chloronitrobenzene and 2-fluorothiophenol, the synthesis of 2-bromo-2'-fluorodiphenyl sulfide (X) was carried out in three steps. The product was converted to the Grignard reagent which reacted with 1-ethoxycarbonyl-4-piperidone and gave the alcohol XIII. Cyclization of this compound with sodium hydride in dimethylformamide afforded 1-ethoxycarbonylspiro(piperidine-4,6'-dibenz[b,e]-1,4-oxathiepin) (V) which was hydrolyzed to the title compound IV. Reduction of compound V with sodium dihydridobis(2-methoxyethoxy)aluminate afforded the 1-methyl derivative III which exhibited antireserpine activity and showed the pharmacological profile of a potential antidepressant.
Synthesis of several 4-hydroxy-3,5-dimethoxybenzamides, their O-substituted derivatives and some related compounds as potential neurotropic agents
Authors: Valenta Vladimír , Protiva Miroslav
Published: September 2010

Reactions of 4-benzyloxy-3,5-dimethoxybenzoyl chloride with pyrrolidine, piperidine, morpholine and 1-methylpiperazine gave the amides IIIa-IIId which were debenzylated by catalytic hydrogenation on palladium. The 4-hydroxy-3,5-dimethoxybenzamides IVa-IVc were then treated with sodium hydride and 2-dimethylaminoethyl chloride to give the O-(2-dimethylaminoethyl)amides Va-Vc. The 3,4,5-trimethoxybenzamide IX was prepared as a homologue of the antiemetic agent "trimethobenzamide" (II) and reduced to the benzylaniline derivative X. The substituted nicotinamide XI was obtained from nicotinoyl chloride and 4-(2-diethylaminoethoxy)aniline. Out of the compounds prepared the amides IIId and Vc had some anticonvulsant activity, the piperazide IVd revealed a significant α-adrenolytic effect and the amino ether X reduced the blood pressure of normotensive rats.
Kinetics of pH equilibration in solutions of hydrogen carbonate during bubbling with a gas containing carbon dioxide
Authors: Lívanský Karel
Published: September 2010

The kinetics of the title process is approximated by differential equations based on kinetic and equilibrium data for carbon dioxide. The course of pH after a sudden change of the concentration of CO2 in the gas is calculated by numerical integration. The course of pH during absorption of CO2 is different from that during desorption. The course of pH during desorption calculated on the assumption that the rate of the noncatalysed hydration of CO2 is sufficient to ensure chemical equilibrium is in good agreement with experimental data from the literature. During absorption of CO2 in a solution of hydrogen carbonate, the chemical reaction rate is sometimes insufficient to ensure chemical equilibrium prior to pH measurement.
Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes
Authors: Vaňura Petr , Makrlík Emanuel
Published: September 2010

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.
Mass transfer accompanied by an irreversible and a consecutive equilibrium reaction
Authors: Hudec Petr , Rod Vladimír
Published: September 2010

Based on the film theory and by means of linearization of the principal differential balance equation an approximate expression has been derived for the enhancement of transfer of species A from the interface by the following reaction with the components B and C: A + mB → nC + pP and A + C ⇄ D. The former of these reactions is irreversible while the second is an equilibrium one. The asymptotic behaviour of the derived relationships has been verified and an error has been estimated of the prediction of the enhancement factor due to the linearization.
The role of aprotic centres on modified aluminas in 1-butanol dehydration
Authors: Paukshtis E. A. , Jirátová Květa , Soltanov R. I. , Yurchenko E. N. , Beránek Ludvík
Published: September 2010

Correlations of the initial rates of butene and dibutyl ether formation from 1-butanol at 300 °C with strength and concentration of aprotic sites on aluminium oxides modified with various ions were examined. It was found that in the formation of dibutyl ether, weak aprotic acidic sites were active. Their specific activity increases with increasing strength of the sites, defined as the heat of adsorption of carbon monooxide, up to the value of 40 kJ/mol. The strongest aprotic sites do not take any important part in the reaction. In butene formation, both types of aprotic acidic sites, weak and strong, are active. It was found that the selectivity in 1-butanol dehydration depended on the concentration of stronger basic sites.
Reaction of vinamidinium salts of furan with aldehydes
Authors: Gracza Tibor , Arnold Zdeněk , Kováč Jaroslav
Published: September 2010

5-(N,N-dimethylamino)-2-furfurylidene-N,N-dimethylimmonium bromide(I) reacts with aromatic aldehydes and its vinylogues to give condensation products II. Addition of alkoxides, sulfinates or thiolates to II renews the furan ring what can be utilized for preparation of new 4-(Ar-, R-methyl)-5-(N,N-dimethylamino)-2-furancarbaldehydes IV.
1H NMR spectra of some juvabione analogues
Authors: Mahajan R. K. , Gupta Neelam , Uppal Satinder K.
Published: September 2010

A number of aromatic aza-analogues of juvabione and dehydrojuvabione have been synthetized by treatment of substituted benzylamine with 3-methylbutanoyl chloride and 3-methyl-2-butenoyl chloride. Reaction of substituted phenoxyacetyl chlorides with isopropylamine and 2-propanol gives other series of aromatic juvabione analogues. The 1H NMR spectra of some analogues are discussed.
Polarography of N,N-dimethyl-4-amino-4'-hydroxyazobenzene in water-methanol mixtures
Authors: Barek Jiří , Kelnar Lubomír
Published: September 2010

The polarographic reduction of N,N-dimethyl-4-amino-4'-hydroxyazobenzene in water-methanol medium was investigated. Evidence is presented for adsorption of the depolarizer on the electrode, and a reduction mechanism is proposed. Conditions are indicated for the determination of this compound in the concentration range 10-4-10-6 mol/l by d.c. polarography, 10-5 to 3 . 10-7 mol/l by Tast polarography, and 10-5-3 . 10-8 mol/l by differential pulse polarography.
Extraction of nitric acid by TBP solutions in kerosene
Authors: Sovilj Milan , Lukešová Svatava , Rod Vladimír
Published: September 2010

Extraction of nitric acid from aqueous solutions to tributyl phosphate-kerosene solvents has been studied in the concentration regions 2-6 kmol m-3 of nitric acid and 0.5-2 kmol m-3 of tributyl phosphate. At these concentration levels, the transfer process is greatly enhanced by interfacial turbulence. This effect was taken into account by the model suggested for the mathematical description of the extraction kinetics.
Kinetics and mechanism of rearrangement and methanolysis of acylphenylthioureas
Authors: Kaválek Jaromír , Jirman Josef , Štěrba Vojeslav
Published: September 2010

S-Acyl-1-phenylthioureas and their 3-methyl derivatives are rearranged to 1-acyl derivatives of thiourea in methanolic solution. The rearrangement of the 1-acyl-1-phenyl derivative to the thermodynamically more stable 3-acyl derivative is subject to specific base catalysis. The rearrangement of acetyl group is about 2 orders of magnitude slower than that of benzoyl group. 1-Acetyl-l-phenylthiourea undergoes base-catalyzed methanolysis (giving phenylthiourea and methyl acetate) instead of the rearrangement. The methanolysis rates of l-acyl-3-phenylthioureas and their N-methyl derivatives have been measured. The acetylthioureas react at most 3x faster than the benzoyl derivatives. The methyl group at the nitrogen adjacent to acyl group accelerates the solvolysis by almost 2 orders of magnitude; the methyl group at the other nitrogen atom retards the solvolysis by almost 1 order of magnitude. Replacement of hydrogen atom by methyl group at the phenyl-substituted nitrogen increases acidity of the phenylacetylthiourea by 2 orders of magnitude. The same replacement at the benzoyl-substituted nitrogen increases the acidity by 3 orders of magnitude, the increase in the case of the acetyl derivative being as large as 4 orders of magnitude.
Preparation of ribosyl derivatives of 1,2,4-triazol-3(2H)-one and 5-methyl-1,2,4-triazol-3(2H)-one
Authors: Hřebabecký Hubert , Beránek Jiří
Published: September 2010

Reaction of the silylated triazolone I with 2,3,5-tri-O-benzoyl-D-ribofuranosyl bromide afforded a mixture of the 4-ribosyltriazolone IXa and 2,3-diribosyltriazolone Xa. Under the same conditions the silylated 5-methyltriazolone II gives the 4-ribosyl derivative XIa and 2-ribosyl derivative XIIa. The 4-phenyl and 4-ribosyltriazoles VII, VIII, IXa and XIa were prepared by an alternative synthesis: cyclisation of l-ethoxymethylene-, l-(l-ethoxyethylidene)-4-phenyl- and 4-ribosylsemicarbazides XIII, XIV, XVa,b and XVIa,b in boiling hexamethyldisilazane in the presence of ammonium sulfate. The semicarbazides XIII, XIV, XVa,b and XVIa,b were obtained by reaction of 4-phenyl- or 4-ribosylsemicarbazide with triethyl orthoformate or diethyl orthoacetate. Compounds XIII and XIV were obtained as the (E)-isomers whereas compounds XV and XVI as mixtures of (Z)- and (E)-isomers XVa,b and XVIa,b, respectively. The benzylation of the triazolones I and II was also studied.
The effect of polymeric and model imidazolium halides on the rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid
Authors: Šorm Miloslav , Procházka Miloslav , Kálal Jaroslav
Published: September 2010

The course of hydrolysis of an ester, 4-acetoxy-3-nitrobenzoic acid catalyzed with poly(1-methyl-3-allylimidazolium bromide) (IIa), poly[l-methyl-3-(2-propinyl)imidazolium chloride] (IIb) and poly[l-methyl-3-(2-methacryloyloxyethyl)imidazolium bromide] (IIc) in a 28.5% aqueous ethanol was investigated as a function of pH and compared with low-molecular weight models, viz., l-methyl-3-alkylimidazolium bromides (the alkyl group being methyl, propyl, and hexyl, resp). Polymers IIb, IIc possessed a higher activity at pH above 9, while the models were more active at a lower pH with a maximum at pH 7.67. The catalytic activity at the higher pH is attributed to an attack by the OH- group, while at the lower pH it is assigned to a direct attack of water on the substrate. The rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid is proportional to the catalyst concentration [IIc] and proceeds as a first-order reaction. The hydrolysis depends on the composition of the solvent and was highest at 28.5% (vol.) of ethanol in water. The hydrolysis of a neutral ester, 4-nitrophenyl acetate, was not accelerated by IIc.
Attempts at the synthesis of 11-methoxysubstituted benzo[c]phenantridines
Authors: Šmidrkal Jan , Holubek Jiří , Šlanger Jiří , Trojánek Jan
Published: September 2010

Experiments aimed at the synthesis of so far unknown 11-methoxybenzo[c]phenanthridines (IIa,b,c) are described. In the first approach 2,3,7,8-tetramethoxybenzo[c]phenanthridine-11-carboxylic acid (IIIb) was synthesized using a procedure for the preparation of 2,3,7,8-bis-methylenedioxybenzo[c]phenanthridine-11-carboxylic acid (IIIa). Attempts to convert the carboxyl group of these acids to the methoxyl group were not successful. In the second approach 3-methoxy-6,7-methylenedioxy-l-methylaminonaphthalene (XX) was prepared from l-(3,4-rnethylenedioxyphenyl)-2-propanone (IX) by a multistep synthesis. On acylation of the product with 2,3-dimethoxy-6-nitrobenzoic acid and subsequent hydrogenation N-(3-rnethoxy-6,7-methylenedioxynaphth-l-yl)-N-methylamide of 6-amino-2,3-dimethoxybenzoic acid (XXII) was obtained. The attempts at its cyclization according to Pschorr were unsuccessful.
Simple theoretical models of elimination reactions on polar catalysts; Dehydration reactivity of secondary alcohols on acidic and basic catalysts
Authors: Sedláček Jiří
Published: September 2010

CNDO/2 calculations for simple models of adsorption and dehydration reactions of secondary aliphatic and aromatic alcohols on polar catalysts are presented. The models involve selected stages of elimination mechanisms of various types (E1, E2 and E1cB elimination). Calculated quantum chemical quantities were correlated with reported experimental data. It is shown that reactivities for the series of substituted phenylethanols correlate very well with the ease of carbonium ion formation. In the case of aliphatic alcohols, calculated quantities correlate generally with the reactivities on SiO2 and are in anticorrelation with the reactivities on Al2O3.NaOH.
Description of vortex turbulent flow of mixed liquid
Authors: Hošťálek Miloslav , Fořt Ivan
Published: September 2010

The article describes a theoretical model of two-dimensional flow of a homogeneous liquid in a cylindrical space delimited by the shell of the mixing tank with a conical bottom, radial baffles and a high-speed axial impeller rotating in a cylindrical draft-tube. By means of the analytical solution of vortex flow equation the mean time flow of turbulent liquid in the vertical cross section of the vessel may be described in the form of Stokes stream function or mean velocity components. The results of theoretical description of the flow are in a good agreement with the experimental values measured by a Pitot direction tube and a hot film anemometer.
Intercalation of uranium hexafluoride into graphite
Authors: Klouda Karel , Rak Václav , Vachuška Josef
Published: September 2010

Intercalation of UF6 into graphite, both from the gaseous phase and from the Ledon 113 solution, was studied. The amount of intercalated UF6 from the gaseous phase was found to be inversely proportional to the size of graphite particles. Intercalation increases with the increasing temperature and surface area of graphite. The contact of gaseous UF6 with graphite led to the formation of β-UF5 that is not intercalated. In the Ledon solution, β-UF5 is not formed. "Passivation" of graphite by elementary fluorine also prevents the formation of β-UF5 but the amount of intercalated UF6 decreases. The intercalation of UF6 into graphite from the gaseous phase is accompanied by the increase of the distance between the parallel carbon atom layers up to the values of about 884 pm. Ternary intercalates graphite-UF6-Ledon 113 are formed during the intercalation of UF6 from the Ledon 113 solutions and the distance between the parallel carbon atom layers is 848-875 pm. Thermogravimetry in the presence of air revealed that the binary intercalates graphite-UF6 decompose in a 3-step reaction while the ternary intercalates decompose in a 4-step reaction. In both cases uranium hexafluoride is not released but acts as a fluorination agent on the graphite carbon.
Evolution thermique de N-oxydes de dimethylamino-5 alcanols-1 substitues en 5. Competition entre rearrangements de cope et de Meisenheimer
Authors: Barbry Didier , Hasiak Bruno , Augait Jean-Michel , Couturier Daniel
Published: September 2010

The effect of the substituent R in the position was studied in the decomposition of 1,5-aminoalcohol N-oxides: Meisenheimer rearrangement takes place when R is the vinyl group but is not observed with the phenyl substituent; elimination to alkenol only affects the more acidic hydrogen atom when R is the allyl or benzyl group; with substituents inducing less important electronic effects (methyl, ethyl), the reaction yields an alkenols mixture with statistical distribution.
6,7-Secoandrostane derivatives
Authors: Velgová Helena , Kohout Ladislav
Published: September 2010

17β-Hydroxy-5-methyl-6-oxa-5β-androstan-3-one (X) and 17β-hydroxy-6,7-seco-4-androsten-3-one (XXV) were prepared as substances with potential biological activity.
Study of potential curves by UHF-type methods. Linearized coupled cluster methods with double substitution
Authors: Klimo Viliam , Tiňo Jozef
Published: September 2010

The potential energy curves have ben calculated for LiH, Li2, and N2 molecules by means of the L-CCD method (Linearized Coupled Cluster Method with Double Substitutions) based on the UHF and RHF reference functions. With each of the molecules, peculiarities are discussed of the description of the curves by the UHF-type methods on the basis of comparison with the full CI or experimental curves. The L-CCD(UHF) method gives a qualitatively correct course within the whole range of internuclear distances.
Evaluation of phase diagrams of solvate-forming binary systems: The systems dimethyl sulphoxide-lithium nitrate and dimethyl sulphoxide-calcium nitrate
Authors: Horsák Ivan , Pacák Petr , Sláma Ivo
Published: September 2010

Phase diagrams of the solidus-liquidus type for two dimethylsulphoxide-nitrate systems have been evaluated using a rigorous method proposed previously. As both the systems involve the formation of solvates, the problem solved is one of simultaneous phase and chemical equilibria. The evaluation was performed by optimization of chosen adjustable parameters, namely the equilibrium constant of solvation, interaction parameters in expression for excess free energy, and the temperature and heat of fusion of pure crystalline solvate. In addition, a suitable model had to be found for the activities of ideal mixture components for the given type of system. The paper presents the first experimental data for the phase diagram of the system dimethyl sulphoxide-lithium nitrate
Formation of the poly(L-lysine) complex with pectin of various esterification degree
Authors: Bystrický Slavomír , Kohn Rudolf , Sticzay Tibor , Bláha Karel
Published: September 2010

The circular dichroic (CD) measurement was chosen the tool to investigate the complex formation of poly(L-lysine) with potassium pectate or pectinate of various esterification degree (E). The polycation-polyanion (pectate, E 0%) 1 : 1 complex was quantitatively formed by an electrostatic interaction independently upon the excess of either component. The partial esterification of pectin resulted in a decrease of complex formation; this drop is at a 20% esterification degree low, at higher esterification degrees (46% and 64%) considerable, and at an esterification degree 86% the complex has not been formed at all. The polypeptide chain was present in the complex in an α-helical arrangement characterized by the CD spectrum; the potential spatial arrangements of the complex were proposed. The α-helical polypeptide component constitutes a core surrounded by a superstructure of D-galacturonan chains.
Topological aspects of chemical reactivity. Reorganisation of electron density in allowed and forbidden reactions
Authors: Ponec Robert
Published: September 2010

The selection rules in chemical reactivity are discussed from the point of view of the differences in the character of the electron density reorganisation in allowed and forbidden reactions. It was shown that the allowed reactions are characterized by the maximum conservation of electron pairing along the whole reaction path. On the other hand for the forbidden reactions a critical point lies on the corresponding concerted reaction coordinate in which one electron pair is completely splitted.
Roentgenographic and thermodynamic study of the existence of mixed crystals in the LaC2-YC2 system
Authors: Hájek Bohumil , Kohout Vladimír , Flemr Vratislav
Published: September 2010

The reaction heats for the mixed crystal formation in the LaC2-YC2 system were obtained from the equilibrium gas pressures measured during the carboreduction. The low positive values of the reaction heats are consistent with the X-ray diffraction study of the carbothermal reduction products of the oxides, where the formation of the (La, Y)C2 dicarbide mixed crystals was only observed in the two side regions up to 25 mol.% of each of the minority components. The composition of the gaseous hydrolysis products of the (La, Y)C2 mixed crystals corresponds to the hydrolysis products of the dicarbide. No methane was detected for samples with low yttrium contents.
Perturbation of steady-state catalytic dehydration of alcohols by pulses of water and other substances
Authors: Morávek Vladimír , Kraus Miloš
Published: September 2010

The dynamic behaviour of systems consisting of 2-propanol or tert-butanol and of a solid dehydration catalyst has been studied by means of pulses of the alcohols, water, nitrogen or carbon dioxide, respectively, introduced onto fresh catalyst surface in a stream of nitrogen, or onto the working surface. The catalysts employed were alumina, alumina modified by fluoride, sulphate or sodium ions, respectively, thoria, silica-alumina, phosphotungstic acid and a sulphonated styrene-divinylbenzene copolymer. The positions and shapes of the response curves allowed to distinguish between catalysts operating by formation of surface alkoxides or of protonated alcohols as surface intermediates in the transformation of the alcohols into alkenes.
29Si (and 13C) NMR spectra of all pertrimethylsilylated O-acetyl and O-benzoyl 1,6-anhydro-β-D-glucopyranose derivatives. A test of empirical assignment rules
Authors: Schraml Jan , Kučár Štefan , Zelený Jan , Chvalovský Václav
Published: September 2010

All O-acetyl-1,6-anhydro-β-D-glucopyranoses and O-benzoyl-1,6-anhydro-β-D-glucopyranoses were pertrimethylsilylated. 29Si and 13C NMR spectra of the pertrimethylsilyl derivatives were measured and the 29Si chemical shifts were used to test two previously described empirical assignment rules. The rule based on the shielding order must be either restricted to the order δ(Si-2) > δ(Si-4) which holds for all the studied compounds or modified for each subclass of the studied compounds with the same O-substituents. The rule based on Hammett type dependence gives correct predictions for Si-3 chemical shifts. When both rules can be applied they yield identical assignments, in other cases they complement each other.