bluuebunny/crossref_metadata_2025 huggingface dataset:
Some New Analogues of Verapamil and Mepamil. Synthesis and Basic Pharmacological Properties
Authors: Butora Gabriel , Bláha Ludvík , Rajšner Miroslav , Helfert Ivan
Published: June 2004

Some new analogues of verapamil (Ia) and mepamil (Ib), calcium antagonists of arylalkylamine type, were synthesized and screened for cardiovascular activities. The basic structure was modified a) on the phenyl ring, attached to the quaternary carbon, b) on the alkyl group, attached to the quaternary carbon and c) on the alkylamino group, attached in position 3 to the n-propyl fragment. Except of 2-(2-chlorophenyl)-2-isopropyl-5-(N-methylhomoveratrylamino)valeronitrile (VIa), all the synthesized compounds exhibited lower hypotensive activity, than the mother compound, verapamil.
Nitriles in Organic Synthesis: Synthesis of New Polyfunctionally Substituted Aromatic Hydrocarbons and Aromatic Heterocycles
Authors: Zayed Salem E. , Harb Abdel-Fattah A. , Elnagdi Mohammed H.
Published: June 2004

Part of our research program is directed to developing new polyfunctionally substituted aromatics as potential agrochemicals. Recently, samples of certain biphenyl, substituted aryls and heterocycles were required.
Activity Coefficients of Tetraalkylammonium Reineckates in Water and Water-Methanol Solutions
Authors: Holba Vladislav
Published: June 2004

The solubilities of tetraalkylammonium diaminetetraisothiocyanatochromates(III) in water and water-methanol solutions were measured at 25 °C as function of ionic strength. The results have been used to evaluate the activity coefficients of the saturating salts. For tetra-1-butylammonium salt the Gibbs free energy of transfer has been determined, and with the use of known ionic transfer function of tetrabutylammonium ion, based on TATB assumption, the Gibbs free energy of transfer of Reineckate anion has been obtained.
Effect of Calcination Temperature on Nickel/Alumina Catalysts
Authors: Ahmed Khaliq , Mistry Pronab
Published: June 2004

Alumina-supported nickel catalysts prepared by the methods of impregnation and coprecipitation and heated at four different temperatures showed that the optimal calcination temperature for both types of catalysts lies in the region of 623-673 K. Crystallite size measurements by XRD revealed that coprecipitated samples have larger crystallites than the impregnated samples. The total surface areas measured by nitrogen adsorption and the results of metal area measurements made by hydrogen adsorption are in agreement with the crystallite size results.
Computer Assisted 13C NMR Identification of Components of Complex Organic Mixtures: Byproducts in the Manufacture of Cyclohexanone
Authors: Střešinková Dagmar , Halmo František , Liptaj Tibor
Published: June 2004

Carbon-13 nuclear magnetic resonance is used to identify components of the distillation residue from the manufacture of cyclohexanone. 13C NMR spectra of rectification fractions provide the data utilized in an algorithm to extract subspectrum resonances specific to each component of the mixture. The subspectra are then subjected to search in 13C NMR library of potential components. A number of components were unambiguously identified in original sample even if moderate peak overlaps occurred. Generated subspectra made also possible identification of substances which are not present in 13C NMR libraries.
Stochastic Modelling of Particle Segregation in a Horizontal Drum Mixer
Authors: Kudrna Vladimír , Hasal Pavel , Rochowiecki Andrzej
Published: June 2004

A process of segregation of two distinct fractions of solid particles in a rotating horizontal drum mixer was described by stochastic model assuming the segregation to be a diffusion process with varying diffusion coefficient. The model is based on description of motion of particles inside the mixer by means of a stochastic differential equation. Results of stochastic modelling were compared to the solution of the corresponding Kolmogorov equation and to results of earlier carried out experiments.
The Mathematical Model of Naphtha Steam Cracking
Authors: Bělohlav Zdeněk , Horák Josef
Published: June 2004

The mathematical model of naphtha steam cracking has been developed to predict products yields. The feedstock composition, feedstock rate, steam-oil ration, inlet temperature, outlet temperature and outlet pressure are introduced as inputs. The reaction model consists of two parts: the radical reactions of higher alkanes, higher alkenes, naphthenes and alkylaromatics and the formal molecular reactions of lower alkanes and lower alkenes. The model was identified using a series of large-scale experiments including four naphtha raw materials. Eight experiments were carried out for each naphtha kind at two levels of the temperature profile, feed rate and steam-oil ratio.
Electrochemical Behaviour of Polyelectrolyte Complex Membranes
Authors: Kůdela Vlastimil , Richau Klaus , Schwarz Hans-Hartmut , Paul Dieter
Published: June 2004

Oriented concentration potentials and DC resistances of Symplex polyelectrolyte membranes made of cellulose sulfate (CS) as a polyanion and of poly(dimethyldiallylammonium chloride) (PDMDAAC) or benzyl-[2-(dodecylcarbamoyl)ethyl]dimethylammonium chloride (Quartolan) as counter-cations were measured and correlated to dialysis permeability coefficients. Concentration potentials showed that the preparation method used leads to membranes with an excess of the charge of one component. Cationic symmetrical PDMDAAC/CS membranes, anionic asymmetrical Quartolan/CS membranes and anionic asymmetrical combination of both types have the fixed ion molarity 0.05, 0.005 and 0.001 mol per litre of imbibed liquid, respectively. Specific resistances are 104 Ω cm in 0.005M and 0.01M-KCl, 103 Ω cm in 0.05M-KCl and even higher in combined membranes. Areal resistances are low due to small membrane thickness. A linear correlation between DC conductivity and permeability has been found. Thus, also Symplex polyelectrolyte membranes can be tested by electrochemical methods.
Preparation and Properties of Chalcones of the Furan Series
Authors: Špirková Katarína , Bobáľ Pavel , Dandárová Miloslava , Alföldi Juraj
Published: June 2004

Preparation and reactions of 1-(5-X-2-furyl)-2-methylsulfonyl-2-furoyl or -2-thienylethylenes with nucleophilic reagents are described. Stereochemistry of selected compounds was studied by NMR spectroscopy.
Substrate Specificity of Carboxylesterase from Vicia faba Roots
Authors: Barthová Jana , Löfellmannová Hana , Beneš Karel
Published: June 2004

Michaelis constants values and limiting rates of the reaction catalyzed by carboxylesterase isolated from the root tips of Vicia faba were determined. 1-Naphthyl acetate, 1-naphthyl butyrate, 1-naphthyl ester of N-acetylglycine, 1-naphthyl ester of L-leucine and 1-naphthyl ester of N-acetyl-L-leucine were used as substrates. The values for the enzyme from control plants were compared with the data for carboxylesterase from plants exposed to the effect of 2,4-dichlorophenoxyacetic acid. An electrophoretic analysis of enzymes from control plants and the tested plants was carried out.
A Spectrophotometric Study of Reversibility of Human Mercaptoalbumin Denaturation by Urea
Authors: Chmelík Josef , Kálal Petr , Kalous Vítěz
Published: June 2004

The renaturation of the human mercaptoalbumin denaturated by urea has been studied spectrophotometrically. The denaturation is reversible up to 15 min treatment with 8 mol dm-3 urea, whereas a longer treatment brings about irreversible changes of the mercaptoalbumin molecule. Samples have been prepared of the renatured mercaptoalbumin pre-denatured by 8 mol dm-3 urea for a period of either 1 min or 200 min. The temperature perturbation differential and derivation spectrophotometries were used to investigate the localization of tyrosyl residues in native mercaptoalbumin and in the renatured forms. From the results it follows that the localization of tyrosyls in the renatured mercaptoalbumin after 1 min denaturation by 8 mol dm-3 urea is the same as that in native protein. On the other hand, the renaturated mercaptoalbumin after 200 min denaturation contains a great number of exposed tyrosyls than is the number in the native protein.
New Substituted Difurylchalcones
Authors: Špirková Katarína , Stankovský Štefan
Published: June 2004

Preparation of 1-(5-substituted-2-furyl)-2-phenylsulfonyl-2-furoyl ethylenes (IIa-IId) using the Lehnert modification of Knoevenagel condensation, as well as substitution nucleophilic reactions of the 1-(5-bromo-2-furoyl)-2-phenylsulfonyl-2-furoyl derivative (IIa) with the corresponding phenolate, thiophenolate and secondary amines are described. IR, UV and 1H NMR spectra of final products are presented.
Preparation of Strong Acid Catalysts by Sulfate Treatment of Calcined Boehmite
Authors: Hochmann Tomáš , Setínek Karel
Published: June 2004

Solid acid catalysts with acid strength of -14.52 < H0 < -8.2 were prepared by sulfate treatment of the samples of boehmite calcined at 105-800 °C. Two preparation methods were used: impregnation of the calcined boehmite with 3.5 M H2SO4 or mixing of the boehmite samples with anhydrous aluminum sulfate, in both cases followed by calcination in nitrogen at 650 °C. The catalysts were characterized by measurements of surface area, adsorption of pyridine and benzene, acid strength measurements by the indicator method and by catalytic activity tests in the isomerization of cyclohexene, p-xylene and n-hexane. Properties of the catalysts prepared by both methods were comparable.
Study of the Conditions for Extraction of Toxic Organic Basis and Methods of Determination I. Extraction of Strychnine with Chlorinated Hydrocarbons
Authors: Belický Ladislav , Souček Jan , Halámek Emil , Havel Josef
Published: June 2004

The conditions for the extraction of strychnine with 1,2,2-tetrachloroethane, chloroform, 1,2-dichloroethane and carbon tetrachloride were studied and described. The distribution and extraction constants were calculated for strychnine in selected solvents from the dependence of the extraction yield on the pH at various ionic strengths. In addition, a study was carried out of the extraction properties of the ion associates of strychnine with selected groups of azodyes with identical basic skeleton but different numbers of sulfo groups.
Investigation of Conditions for the Determination of Pesticides in Water Using Solid Phase Extraction
Authors: Tatarkovičová Věra , Machač Radek
Published: June 2004

The conditions for the preconcentration of carbamate, phenylurea and triazine pesticides from water samples were investigated, and optimized methods were developed for the determination of the pesticide groups. Bakerbond spe C18 cartridges were used for the preconcentration. The preconcentrated carbamate and phenylurea pesticides were eluted from the cartridges with acetone, whereas the triazine herbicides were eluted with chloroform. After additional concentration by evaporation, the eluates were analyzed by RC-HPLC on an AQUAPORE RP-300 column using a methanol-water mixture as the mobile phase.
Structure of Sodium Hydrogen Selenite-Selenious Acid Adduct (1:3), NaHSeO3.3H2SeO3
Authors: Loub Josef , Mička Zdeněk , Podlahová Jana , Malý Karel , Kopf Jürgen
Published: June 2004

Structure of sodium hydrogen selenite-selenious acid (1:3) was solved by heavy-atom method and refined anisotropically to R = 0.098 for 1223 unique observed reflections. The title compound crystallizes in the Pc space group with a = 5.756(2), b = 4.911(2), c = 20.010(5) Å, β = 100.48(3)°, V = 556(1) Å3, T = 293 K, (a = 5.763(2), b = 4.878(1), c = 20.03(1) Å, β = 100.48(3)°, V = 554(1) Å3, T = 173 K), Z = 2. The structure consist of HSeO3- anions, molecules of selenious acid and Na+ cations which are octahedrally coordinated with oxygen atoms. The structure is stabilized by a system of hydrogen bonds.
Conformation Dependent Cyclizations of 1,3,3,5-Tetraphenylpentane-1,5-dione
Authors: Šebek Pavel , Novotný Jiří , Kratochvíl Bohumil , Schwarz Marián , Kuthan Josef
Published: June 2004

The molecular and crystal structure of 1,3,3,5-tetraphenylpentane-1,5-dione (I) obtained from direct methods and anisotropically refined by the least-squares method shows that the two 3,3-phenyl groups force the molecule into a conformation suitable for formation of cyclic products and intermediates. Compound I crystallizes in P1 group with lattice parameters a = 8.444(1), b = 10.195(2), c = 14.618(2) Å, α = 75.52(2)°, β = 73.22(1)°, γ = 65.47(1)°. Photochemically and thermally found was the system I ↔ II. The reaction of 1,5-dione I with phenylmagnesium bromide gives the 2,3-dihydropyran derivative III, whereas complex hydrides give a mixture of IV and VI. On treatment with magnesium, the diketone I gives diol VIII. Chlorine (Cl2) reacts with compound I to give the mono-, di-, and tetrachloro derivatives XII, XIII, and XIV, respectively. Bromine (Br2) produces 3,5-dibromo-4H-pyran derivative XVIII, whereas I2 only catalyzes the formation of 4H-pyran V. The formylation of dione I with dimethylformamide and POCl3 gives the 4H-pyran-3-carbaldehyde XX. Probable mechanisms of the reactions investigated and the stereochemistry of compounds VI, VIII, XIII, and XIV are discussed.
Synthesis of Oximes in the Microwave Oven
Authors: Puciová Monika , Toma Štefan
Published: June 2004

The synthesis of a broad range of oximes has been studied. It was found that the application of microwave heating enhanced dramatically the reaction rate, and practically quantitative yields of oximes were isolated after less than 1-min heating in the most cases. The effect of solvents on the course of the reaction was also studied.
Some Problems of Reaction Kinetics and Mechanisms over Decaying Catalysts
Authors: Kumbilieva Krasimira E. , Kiperman Savelii L. , Petrov Lachezar A.
Published: June 2004

In this review, recent investigations by the authors of certain aspects of the kinetics of processes accompanied by catalyst deactivation are summarized. Correlation of the data with reaction mechanism is discussed.
A Contribution to the Structure Characteristics and Phase Composition of Vanadium-Phosphorus Catalysts Prepared from the VOPO4.xH2O.yH3PO4 Precursor
Authors: Brutovský Milan , Gerej Štefan , Novák Ján , Ferdinandyová Lucia
Published: June 2004

Catalysts were prepared from VOPO4.xH2O.yH3PO4 (x = 0.3-2, y = 0.2-0.85) by reduction with SO2 up to a final temperature of 750-800 °C, and activated in a reaction mixture of 1.0-1.4% butane in air up to 500 °C. The structure characteristics and phase composition of the catalysts were found to be affected by the preparation procedure and heat treatment regime. Their diffraction lines and IR spectra revealed that the catalysts from larger and less defective crystals than catalysts which were obtained from the VOHPO4.xH2O.yH3PO4 precursor and activated in the reaction mixture at temperatures up to 500 °C. In the catalysts prepared by the above procedure, the tendency to the formation of phases of higher-condensed phosphates, in particular VO(PO3)2 or even V(PO3)3, increases with increasing n(P):n(V) ratio and is then more pronounced than with vanadium-phosphorus catalysts prepared by other procedures. The tendency to the formation of the catalytically less active condensed phosphates is partly suppressed by the embedding of modifying metal cations (Fe or Cu in this case).
Surface Properties and Catalytic Behaviour in Thiophene Hydrodesulfurization on Mo- and NiMo-Modified HZSM-5 Zeolites
Authors: Spojakina Alla A. , Kostova Nina G.
Published: June 2004

Zeolite HZSM-5 containing 1 wt.% Ni and 10 wt.% Mo has been investigated using IR spectroscopy and thiophene hydrodesulfurization (HDS). The IR spectra indicate the strong interaction of molybdenum and nickel with zeolite lattice, forming polymolybdates of different composition. The acidity of the samples is influenced by the composition and reduction treatment. The zeolite is found to exhibit shape selectivity during thiophene conversion.
Comparison of Selectivity of Ni, Mo, and Ni-Mo Sulfide Catalysts in Parallel Hydrodenitrogenation and Hydrodesulfurization
Authors: Drahorádová Alexandra , Zdražil Miroslav
Published: June 2004

Selectivity of hydrodenitrogenation/hydrodesulfurization (HDN/HDS) using carbon supported Ni, Mo, and Ni-Mo sulfide catalysts was studied at a pressure of 2 MPa and over a temperature range of 280-350 °C. A commercial alumina supported Ni-Mo sample was also included as reference catalyst. Model compounds used were pyridine and thiophene. Selectivity (HDN/HDS) increased with decreasing temperature and decreased in the order Ni, Mo, Ni-Mo. Ni/C catalyst exhibited unusually high HDN/HDS selectivity at low temperature, where HDN of pyridine was faster than HDS of thiophene. Selectivity was interpreted as an intensive property of a catalyst characterizing quality of active surface. The combination of Ni and Mo sulfides in Ni-Mo catalyst resulted in a strong shift in HDN/HDS selectivity to the HDS side; the selectivity of Ni-Mo sample was very low and was not an average of the selectivities of Ni and Mo catalyst. This was interpreted as the evidence of the chemical synergism in the Ni-Mo sulfide system, because structure synergism cannot cause such selectivity changes accompanying combination of Ni and Mo sulfide into the mixed catalyst.
Mn-Mo-O Catalysts for Methanol Oxidation. II. Oxidation of Methanol
Authors: Ivanov Krasimir , Litcheva Penka , Klissurski Dimitar
Published: June 2004

The catalytic properties of MnMoO4-based catalysts toward methanol oxidation are investigated. The effect of temperature, flow rate and gas mixture composition on the catalytic activity is established. The highest activity and selectivity (comparable with those of industrial catalysts) of the samples obtained by precipitation in the presence of a small excess of MoO3 was found. The oxidation of methanol on MnMoO4-based catalyst is proposed to be a two-step process. The first step includes methanol interaction with Mo(VI) and reduction of Mo(VI) to Mo(V) (Mo(IV)). The second step consists in direct oxidation of the reduced molybdenum by oxygen from the alcohol-air mixture.
Methanol Carbonylation Catalyzed by Rhodium Complexes Immobilized to Silica via Pyridine Group
Authors: Čapka Martin , Schubert Ulrich , Heinrich Bernd , Hjortkjaer Jes
Published: June 2004

2-(2-Trimethoxysilylethyl)pyridine (I) was used to prepare a series of rhodium carbonyl complexes bound to silica via pyridine group. The rhodium complex Rh2(CO)4Cl2 (Rh2) was used as a starting compound, and the immobilized complexes were prepared by the following routes: (i) by the reaction of untreated silica with a Rh complex formed from Rh2 and I, (ii) by reaction of Rh2 with a silica functionalized with I, (iii) by treatment of Rh2 with a polycondensate prepared by hydrolysis and condensation of a mixture of I and tetraethoxysilane, and (iv) by sol-gel processing of tetraethoxysilane with a Rh complex formed from Rh2 and I. These complexes were found to be efficient catalysts for the liquid phase methanol carbonylation. Their activity and stability in relation to their synthesis and structure is discussed, along with Rh leaching process.
Addition of Tetrachloromethane to Styrene Catalyzed by Copper-Chiral Amine Complexes
Authors: Kotora Martin , Hájek Milan , Döbler Christian
Published: June 2004

Copper(I)-chiral amine complexes were found to be very efficient catalysts for addition reaction of tetrachloro- and bromotrichloromethane with styrene (yields over 90%). However, both monodentate and bidentate chiral amine ligands (I-VIII) gave a low asymmetric induction (up to 2.3% ee).
In,out-Isomerism of Phosphorus Bridgehead Cage Compounds. A Review
Authors: Bauer Ingmar , Habicher Wolf D.
Published: June 2004

The chemistry and stereochemical peculiarities, especially the phenomenon of in,out-isomerism of bi- and polycyclic compounds with one or more phosphorus bridgehead atoms, are reviewed in the present paper. The appearance of in,out-isomers depends on the ring size of the bi- and polycycles. In general graphic in,out-isomerism becomes only possible in medium sized ring systems and in particular in macrocyclic compounds. However even bicyclic systems containing small rings can be trans-configured if the third chain is long and flexible enough hence giving rise to pseudo-in,out-isomerism. In-phosphorus atoms exhibit a low reactivity in comparison to their out-counterparts. Nevertheless some few examples of reactions at in-positioned phosphorus atoms have been presented. This will potentially open the way to a specific modification of the cavity of such macrobi- and polycyclic compounds. A review with 53 references.
Remediation and Liquid-Liquid Phase Transfer Extraction of Chromium(VI). A Review
Authors: Memon Shahabuddin , Roundhill D. Max , Yilmaz Mustafa
Published: June 2004

Chromium(VI) is a widely used industrial chemical, and is generally considered to pose a greatest human health risk because it is more toxic, more soluble, and more mobile than chromium(III). Workers in industries that use chromium, in particular stainless steel welding, chromate production, chromium plating, and chrome pigment industries, where exposure via inhalation of aerosols is primarily to hexavalent chromium, are at increased risk of chromium effects. In this article we demonstrate various studies regarding remediation methods in particular liquid-liquid extraction of chromate and dichromate anions with various functionalized calixarenes. This review article briefly discusses various molecular designs of calixarene-type macrocycles for chromium(VI) oxoanion recognition, and gives examples on the relationship between structure and selectivity. The article does not, however, attempt to cover all of the different approaches to chromium(VI) extraction. A review with 73 references.
X-ray Crystallographic Study of Alkylammonium Anthracene-9-carboxylates as a Model for Fibrous Structure of Binary Anthracene Salt Gels
Authors: Tani Tahahiro , Sada Kazuki , Ayabe Masatsugu , Iwashita Yuya , Kishida Takanori , Shirakawa Michihiro , Fujita Norifumi , Shinkai Seiji
Published: June 2004

Crystal structure of hexylammonium anthracene-9-carboxylate was investigated. The salt was arranged by a one-dimensional hydrogen bond network to form a columnar structure in the crystalline state. This columnar structure should be the model of fibrous assemblies in the organogels of anthracene-9-carboxylate alkylammonium salts having a long alkyl chain.
Patterns of distribution of microfungi in decomposing bog and fen plants
Authors: Thormann Markus N , Currah Randolph S , Bayley Suzanne E
Published: June 2004

The microfungal assemblages from the litter of the dominant vegetation of a forested bog and a riverine, sedge-dominated fen in southern boreal Alberta, Canada, were investigated over a 2-year period. Canonical correspondence analyses showed distinctly different fungal communities associated with litter of the dominant plant species of this bog (Sphagnum fuscum (Schimp.) Klinggr.) and fen (Carex aquatilis Wahlenb. leaves and rhizomes and Salix planifolia Pursh leaves and roots). Plant tissue quality variables, including total phosphorus and total nitrogen tissue concentrations, correlated most strongly with the fungal communities. In contrast, site-specific environmental (surface water chemical variables) and physical (peat and water temperatures, water level) variables were not correlated with the fungal communities of these five decomposing fen and bog plant litters. Of 93 identified fungal taxa, 25% occurred exclusively in the bog and 56% occurred exclusively in the fen. Eighteen species (19%) were common to the materials examined from both peatlands. Several species of (i) Aspergillus, Mortierella, and Oidiodendron were restricted to the Sphagnum litter in the bog, and species of (ii) Phialophora, Phialocephala, Fusarium, Dimorphospora foliicola, Monocillium constrictum, and several basidiomycetes were restricted to the Carex and Salix plant litters in the fen. These taxa constitute components of the bog and fen fungal communities, respectively.Key words: fungal communities, decomposition, bog, fen, canonical correspondence analysis (CCA).
Reassessment of the pits and antipits in soybean seeds
Authors: Ma Fengshan , Peterson Carol A , Gijzen Mark
Published: June 2004

A soybean (Glycine max (L.) Merr.) cotyledon has a concave region on its abaxial center called a pit, and the seed coat has a corresponding convex region on its inner surface called an antipit. While it is clear that the pit is lined with large epidermal cells, the anatomical identity of the antipit has been a subject of confusion. The inner surface of the seed coat consists of a compressed endosperm tissue that is subtended by an aleurone layer. In the antipit region of the seed coat, additional endosperm cells are situated between the aleurone layer and the compressed endosperm tissue. These endosperm cells, called cone cells, are similar to ordinary aleurone cells in basic structure. In the present study, it is demonstrated that the surface ornamentations of the antipit are a print of the pit on the compressed endosperm tissue. The functional aspects of the antipitpit complex are not known. It was previously postulated that the antipitpit region has an enhanced capability of nutrient translocation to the growing embryo, but there is little evidence to support this hypothesis. Alternatively, the antipitpit association may provide a structural feature that anchors the embryo within the seed coat while contributing to an overall spherical shape of the seed.Key words: antipit, endosperm, Glycine max, pit, seed coat, soybean.
The effect of two arbuscular mycorrhizal inocula of contrasting richness and the same mycorrhizal potential on the growth and survival of wild plant species from La Gran Sabana, Venezuela.
Authors: Cuenca Gisela , Andrade Zita De , Lovera Milagros , Fajardo Laurie , Meneses Erasmo
Published: June 2004

Diversity of arbuscular mycorrhizal fungi (AMF) is potentially important for the productivity and functioning of plant communities. However, from results published to date, it is unclear whether the increase in productivity and plant diversity obtained with increased AMF richness is a consequence of higher richness in itself or whether it is caused simply by an uncontrolled, higher mycorrhizal potential in the more diverse AMF inocula used. The aim of the present work was to evaluate the effect of AMF richness on the biomass and survival of several wild plant species from La Gran Sabana, Venezuela, comparing AMF inocula of varying richness but with similar mycorrhizal potential. We studied the effect of two inocula (containing two and five AMF species respectively, each with 600 propagules/100 g of soil) on growth and survival in a community composed of three woody species indigenous to La Gran Sabana. No differences were found in dry mass production or plant survival when the two inocula of contrasting richness were compared. Reasons for such results include the life history strategies of the AMF used in the present work.Key words: arbuscular mycorrhizal fungi, arbuscular mycorrhizal fungal diversity, microcosm, species richness, biodiversity, tropical species.
A morphological examination of Frustulia (Bacillariophyceae) from the Ocala National Forest, Florida, USA
Authors: Siver Peter A , Baskette George
Published: June 2004

The genus Frustulia was found to be an abundant and important component of the attached algal community in a suite of dilute, poorly buffered, and acidic ponds situated in the Ocala National Forest in north-central Florida. Six species were found in the study, including Frustulia krammeri Lange-Bertalot & Metzeltin, Frustulia saxonica Raben horst, Frustulia crassinervia (Brébisson) Lange-Bertalot & Krammer, Frustulia pseudomagaliesmontana Camburn & Charles, Frustulia bahlsii Edlund & Brant, and a newly described taxon, Frustulia trochus Siver & Baskette sp. nov. In addition, an emended description is provided for F. pseudomagaliesmontana. Each species was studied in detail with both light and scanning electron microscopy, and the importance of specific morphological characters was also examined with principal components analysis. In addition to valve shape and size, striae density and areolae density, the structure of the helictoglossae, raphe fissures, and areolae were all found to be useful and important characters in distinguishing among species. Three distinct types of helictoglossae, referred to as linear, rolled tongue, and hoop shaped, are discussed. Taxa with linear or rolled-tongue-shaped helictoglossae also had T-shaped raphe fissures and circular hymen coverings. Taxa with hoop-shaped helictoglossae had teardrop-shaped raphe fissures and rectangular hymen coverings. K-cluster analysis was used to examine the distinction between F. krammeri and F. saxonica relative to the historical separation of F. rhomboides from F. saxonica.Key words: acidic ponds, Florida, Frustulia, Frustulia trochus, new species, Ocala National Forest.
Resilience of mycorrhizal fungi on defoliated and fertilized hybrid poplars
Authors: Kosola K R , Durall D M , Robertson G P , Dickmann D I , Parry D , Russell C A , Paul E A
Published: June 2004

We examined the effects of fertilization and gypsy moth defoliation of hybrid poplar (Populus ×canadensis Moench 'Eugenei') on ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) fungal colonization, ECM richness, and ECM composition in the summers of 1997 and 1998. The factorial experiment included two levels of defoliation (defoliated and control) and fertilization (100 kg N·ha1and control). Gypsy moth (Lymantria dispar L.) populations were manipulated to obtain defoliation in the summer of 1996, 1997, and 1998; fertilization subplots were fertilized with NH4NO3(100 kg N·ha1) in the spring of these years. There were no significant effects of defoliation on ECM or AM colonization in either year; there was a significant (p ≤ 0.05) decline in AM colonization in fertilized plots in 1997 and a significant interaction between defoliation and fertilization effects on ECM colonization in 1997. In the nondefoliated plots, ECM fungal colonization increased, whereas AM colonization decreased because of fertilization. In the defoliated plots, neither ECM nor AM colonization was affected by fertilization. ECM community composition and richness were unchanged by any treatment. The small and transient effects of defoliation and fertilization on poplar AMs and ECMs demonstrate the tolerance of these early-successional trees to defoliation and their ability to rapidly use high levels of available nitrogen.Key words: Populus, nitrogen, ectomycorrhizas, arbuscular mycorrhizas, ectomycorrhizas, Lymantria dispar (gypsy moth), defoliation.
BAROTROPIC FRW COSMOLOGIES WITH A DIRAC-LIKE PARAMETER
Authors: ROSU H. C. , LÓPEZ-SANDOVAL R.
Published: June 2004

Using the known connection between Schrödinger-like equations and Dirac-like equations in the supersymmetric context, we discuss an extension of FRW barotropic cosmologies in which a Dirac mass-like parameter is introduced. New Hubble cosmological parameters HK(η) depending on the Dirac-like parameter are plotted and compared with the standard Hubble case H0(η). The new HK(η) are complex quantities. The imaginary part is a supersymmetric way of introducing dissipation and instabilities in the barotropic FRW hydrodynamics.
STUDY OF SINGLE-PARTICLE RESONANT STATES
Authors: ZHANG SHISHENG
Published: June 2004

Energies and widths for single-particle resonant states in the continuum in 120 Sn , as the necessary input quantities of relativistic random phase approximation for the investigation of isoscalar giant octupole resonance, are determined by analytic continuation in the coupling constant (ACCC) method within the framework of self-consistent relativistic mean field (RMF) theory for the first time. For the effective interaction NL3, the results in this scheme agree well with those of scattering phase shift method on the basis of RMF. Similar calculations are carried out in neutron-rich nucleus 84 Ni .
DUALISM BETWEEN PHYSICAL FRAMES AND TIME IN QUANTUM GRAVITY
Authors: MERCURI SIMONE , MONTANI GIOVANNI
Published: June 2004

In this work we present a discussion of the existing links between the procedures of endowing the quantum gravity with a real time and of including in the theory a physical reference frame.

More precisely, as a first step, we develop the canonical quantum dynamics, starting from the Einstein equations in presence of a dust fluid and arrive at a Schrödinger evolution. Then, by fixing the lapse function in the path-integral of gravity, we get a Schrödinger quantum dynamics, of which eigenvalues problem provides the appearance of a dust fluid in the classical limit.

The main issue of our analysis is to claim that a theory, in which the time displacement invariance, on a quantum level, is broken, is indistinguishable from a theory for which this symmetry holds, but a real reference fluid is included.
DYNAMICS OF MOLECULAR MAGNET Fe8 INTERACTING WITH AN INJECTING SPIN-POLARIZED ELECTRON
Authors: ZHANG GUO-FENG , WEN YIN , GAO YING-FANG , LIANG JIU-QING , YAN QI-WEI
Published: June 2004

Quantum dynamics time evolution of a molecular magnet Fe 8 interacting with an electron nuclear spin is studied by solving the time-dependent Schrödinger equations. It is found that the variation of Fe 8 magnetization and the nuclear spin crucially depends on the interaction strength. The time evolution of the entanglement between the injecting electron and Fe 8 is evaluated. It is observed that the entanglement oscillates in time and is tightly related to the spin variation of the injecting electron. From these characteristics, the technique for the reversing and read-out of Fe 8 spin states is suggested.
NON-EXTENSIVE STUDY OF RIGID AND NON-RIGID ROTATORS
Authors: BAĞCI GŎKHAN B. , SEVER RAMAZAN , TEZCAN CEVDET
Published: June 2004

The isotropic rigid and non-rigid rotators in the framework of Tsallis statistics are studied in the high and low temperature limits. The generalized partition functions, internal energies and heat capacities are calculated. Classical results of the Boltzmann–Gibbs statistics have been recovered as non-extensivity parameter approaches to 1. It has also been observed that non-extensivity parameter q behaves like a scale parameter in the low temperature regime of the rigid rotator model.
ON ISOMORPHISM OF LIE ALGEBRAS WITH ONE DEFINING RELATION
Authors: MIKHALEV ALEXANDER A. , SHPILRAIN VLADIMIR , UMIRBAEV UALBAI U.
Published: June 2004

Let L be a finitely generated free Lie algebra. We construct an example of two elements u and v of L such that the factor algebras L/(u) and L/(v) are isomorphic, where (u) and (v) are ideals of L generated by u and v, respectively, but there is no automorphism φ of L such that φ(u)=v.
INVOLUTED SEMILATTICES AND UNCERTAINTY IN TERNARY ALGEBRAS
Authors: BRZOZOWSKI J. A.
Published: June 2004

An involuted semilattice  is a semilattice  with an involution-: S→S, i.e.,  satisfies [Formula: see text], and [Formula: see text]. In this paper we study the properties of such semilattices. In particular, we characterize free involuted semilattices in terms of ordered pairs of subsets of a set. An involuted semilattice  with greatest element 1 is said to be complemented if it satisfies a∨ā=1. We also characterize free complemented semilattices. We next show that complemented semilattices are related to ternary algebras. A ternary algebra  is a de Morgan algebra with a third constant ϕ satisfying [Formula: see text], and (a+ā)+ϕ=a+ā. If we define a third binary operation ∨ on T as a∨b=a*b+(a+b)*ϕ, then  is a complemented semilattice.
Elafin-overexpressing mice have improved cardiac function after myocardial infarction
Authors: Ohta Kunio , Nakajima Takanori , Cheah Alexander Y. L. , Zaidi Syed H. E. , Kaviani Nilo , Dawood Fayez , You Xiao-Mang , Liu Peter , Husain Mansoor , Rabinovitch Marlene
Published: June 2004

Elevated serine elastase activity after myocardial infarction can contribute to remodeling associated with left ventricular dilatation and dysfunction. We therefore assessed the effects of overexpressing the selective serine elastase inhibitor elafin in transgenic mice in which a myocardial infarction was caused by ligation of the left anterior descending coronary artery (LAD). Elevated serine elastase activity was observed in nontransgenic littermates as early as 6 h after LAD ligation and persisted at 4 and 7 days but not in sham-operated or elafin-overexpressing transgenic mice. Myeloperoxidase activity (index of inflammatory cells) and matrix metalloproteinase 2 were also increased but only at 4 and 7 days and only in nontransgenic mice ( P < 0.05 for both comparisons), and this increase correlated with inflammatory cell infiltration. Echocardiographic study at 4 days revealed indexes of diastolic dysfunction in nontransgenic versus elafin-overexpressing mice ( P < 0.05). Morphometric and biochemical analyses at 28 days indicated impairment in cardiac performance, with greater scar thinning and infarct expansion in nontransgenic versus elafin transgenic littermates ( P < 0.05 for all comparisons). Thus serine elastase inhibition appears to suppress inflammation, cardiac dilatation, and dysfunction after myocardial infarct.
New insights into the pathological role of TNF-α in early cardiac dysfunction and subsequent heart failure after infarction in rats
Authors: Berthonneche C. , Sulpice T. , Boucher F. , Gouraud L. , de Leiris J. , O'Connor S. E. , Herbert J.-M. , Janiak P.
Published: June 2004

A marked increase in plasma TNF-α has been described in patients with chronic heart failure (CHF). Nevertheless, little is known about the direct role of this cytokine early after myocardial infarction (MI) and its possible effects on the subsequent development of CHF. Wistar rats were subjected to permanent in vivo coronary artery ligation. At 5, 7, and 9 days after MI, cardiac function, passive compliance of the left ventricle (LV), and cardiac geometry were evaluated. The same model was used to perform pharmacological studies 7 days and 10 wk after MI in rats treated with monomeric recombinant human soluble TNF-α receptor type II (sTNF-RII, 40 μg/kg iv) or a placebo on day 3. Maximal alterations of cardiac function and geometry occurred 7 days after MI, which correlated chronologically with a peak of cardiac and serum TNF-α, as shown by immunohistochemistry and ELISA, respectively. sTNF-RII improved LV end-diastolic pressure under basal conditions and after volume overload 7 days and 10 wk after MI. Moreover, a significant leftward shift of the pressure-volume curve in the sTNF-RII-treated group 7 days after MI indicated a preservation of LV volume. Infarct expansion index was also significantly improved by sTNF-RII 7 days after MI ( P < 0.01). Nevertheless, 10 wk after MI, geometric indexes and passive pressure-volume curves were not significantly improved by the treatment. In conclusion, TNF-α plays a major role in cardiac alterations 7 days after MI in rats and contributes to hemodynamic derangement, but not to cardiac remodeling, in subsequent CHF.
Modulation of Associative Human Motor Cortical Plasticity by Attention
Authors: Stefan Katja , Wycislo Matthias , Classen Joseph
Published: June 2004

The role of attention in generating motor memories remains controversial principally because it is difficult to separate the effects of attention from changes in kinematics of motor performance. We attempted to disentangle attention from performance effects by varying attention while plasticity was induced in human primary motor cortex by external stimulation in the absence of voluntary movement. A paired associative stimulation (PAS) protocol was employed consisting of repetitive application of single afferent electric stimuli, delivered to the right median nerve, paired with single-pulse transcranial magnetic stimulation (TMS) over the optimal site for activation of the right abductor pollicis brevis muscle (APB) to generate near-synchronous events in the left primary motor cortex. In experiment 1, the spatial location of attention was varied. PAS failed to induce plasticity when the subject's attention was directed to their left hand, away from the right target hand the cortical representation of which was being stimulated by PAS. In experiment 2, the grade of attention to the target hand was manipulated. PAS-induced plasticity was maximal when the subject viewed their target hand, and its magnitude was slightly reduced when the subject could only feel their hand. Conversely, plasticity was completely blocked when the subject's attention was diverted from the target hand by a competing cognitive task. A similar modulation by attention was observed for PAS-induced changes in the duration of the silent period evoked by TMS in voluntarily contracted muscle. Associative plasticity in the human motor cortex depends decisively on attention.
A Modified Revisited Haseman-Elston Method to Further Improve Power
Authors: Wang Tao , Elston Robert C.
Published: June 2004

The original and revisited Haseman-Elston methods are simple robust methods to detect linkage, but neither is uniformly optimal in terms of power. In this report, we propose a simple modification of the revisited Haseman-Elston method that retains the simplicity and robustness properties, but increases its power. We demonstrate theoretically that the modification can be more powerful than the optimally weighted Haseman-Elston method when the sibship mean can be correctly specified. We then examine the properties of this modification by simulation when the sibship mean is replaced by its best linear unbiased predictor. The simulation results indicate that this modification maintains good control over type I error, even in the case of larger sibships, and that the empirical power of this modification is similar to that of the optimally weighted Haseman-Elston method in most cases.
Mitochondria-Targeting Drug Oligomycin Blocked P-Glycoprotein Activity and Triggered Apoptosis in Doxorubicin-Resistant HepG2 Cells
Authors: Li Y.C. , Fung K.P. , Kwok T.T. , Lee C.Y. , Suen Y.K. , Kong S.K.
Published: June 2004

Background: Mitochondria are key regulators in apoptosis. This suggests that a mitochondrion can be a target for cancer treatment. To examine the feasibility of this approach, we investigated the effect of oligomycin on the induction of apoptosis in drug-resistant cells. As a mitochondrion-targeting agent, oligomycin inhibits mitochondrial F₀F1-ATPase. Of 37,000 molecules tested against the 60 human cancer cell lines of the National Cancer Institute, oligomycin is among the top 0.1% most cell line selective agents. Methods: Changes in the doxorubicin (Dox) accumulation and mitochondrial potential (Δψm) in human hepatocarcinoma HepG2 and its derivative R-HepG2 with Dox resistance were determined by flow cytometry. P-glycoprotein (Pgp) expression and release of cytochrome c from mitochondria were analyzed by Western blot. Cytotoxicity was examined by DNA fragmentation and the alamar blue assay. Results: R-HepG2 cells produced Pgp, showed drug resistance and accumulated less Dox when compared to their parent. In both cell lines, oligomycin depolarized Δψm, released cytochrome c and elicited DNA fragmentation. Moreover, oligomycin blocked Pgp activity and accumulated more Dox in R-HepG2. Combined treatment with Dox and oligomycin elicited more cell death. Conclusion: Our results suggest that oligomycin could bypass Dox resistance and trigger apoptosis in R-HepG2 cells.
Differential Efficacy of Clarithromycin in Lung versus Thigh Infection Models
Authors: Maglio Dana , Capitano Blair , Banevicius Mary Anne , Geng Qiuming , Nightingale Charles H. , Nicolau David P.
Published: June 2004

Background: Differences in clarithromycin disposition and the resulting changes in bacterial density were studied using mouse lung and thigh infection models. Methods: Clarithromycin activity was evaluated against seven Streptococcus pneumoniae isolates with efflux-mediated resistance in both murine lung and thigh infection models. Intrapulmonary disposition of clarithromycin was also studied. Results: Consistent bacterial kill was observed in the lung model, whereas no drug effect was observed in the thigh model. Conclusion: These differences in bacterial density were supported by high concentrations observed in epithelial lining fluid as compared to serum.
Therapeutic Efficacy of Moxifloxacin, a New Quinolone, in the Treatment of Experimental Intra-Abdominal Abscesses Induced by Bacteroides fragilis in Mice
Authors: Thadepalli Haragopal , Chuah See Kean , Gollapudi Sastry
Published: June 2004

Moxifloxacin, a new quinolone, is effective in vitro against several anaerobic bacteria including Bacteroides fragilis, but its in vivo activity against anaerobic infections is not known. In this study, we evaluated the in vivo activity of moxifloxacin in the treatment of experimentally induced intra-abdominal abscesses (IAA) caused by B. fragilis. For comparison, clindamycin, metronidazole, and levofloxacin were used, and saline for control. Absence of bacteria (sterile) in the abscess pus was required to call it a cure. Mice were intraperitoneally injected with B. fragilis plus sterile rat feces and barium sulfate. Animals were treated with moxifloxacin (40 mg/kg/b.i.d.), clindamycin (75 mg/kg/b.i.d.), levofloxacin (40 mg/kg/b.i.d.) or metronidazole (75 mg/kg/b.i.d.) for 10 days. The cure rate was 12% in controls on saline therapy, 57% on metronidazole, 67% on levofloxacin, 73% on moxifloxacin and 79% on clindamycin. The therapeutic efficacy of moxifloxacin in this B. fragilis infection was not significantly different from that observed with clindamycin. By virtue of its established efficacy on gram-negative aerobic bacteria and the observed in vivo efficacy on B. fragilis, moxifloxacin can be evaluated in the treatment of clinical anaerobic infections.
Addition of Teicoplanin or Vancomycin for the Treatment of Documented Bacteremia due to Gram-Positive Cocci in Neutropenic Patients with Hematological Malignancies: Microbiological, Clinical and Economic Evaluation
Authors: D’Antonio D. , Staniscia T. , Piccolomini R. , Fioritoni G. , Rotolo S. , Parruti G. , Di Bonaventura G. , Manna A. , Savini V. , Fiorilli M.P. , Di Giovanni P. , Francione A. , Schioppa F. , Romano F.
Published: June 2004

A prospective, randomized, double-blind trial was conducted on 124 febrile patients with hematological malignancies to compare teicoplanin with vancomycin as an addition to the initial empiric amikacin-ceftazidime regimen after documented bacteremia due to gram-positive cocci. At enrolment, patients in both groups were comparable with respect to age, sex, underlying hematologic disorders and duration of neutropenia. Rates of therapeutic success were 55/63 (87.3%) in the teicoplanin group and 56/61 (91.8%) in the vancomycin group (p = 0.560). The mean duration of treatment was similar, being 12.2 and 11.4 days, respectively (p = 0.216). Patients treated with teicoplanin remained febrile for slightly longer than those treated with vancomycin (4.9 vs. 4.0 days) (p = 0.013). Thirteen patients experienced an adverse drug reaction, but without any significant difference in the two arms. Isolated staphylococci showed a progressive and significant decrease in susceptibility to both glycopeptides during the 8 study years. The economic analysis performed showed that the addition of vancomycin is cost-saving.