bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phenol degradation by a Graphium sp. FIB4 isolated from industrial effluents
Authors: Santos Vera L. , Heilbuth Nádia M. , Braga Danúbia T. , Monteiro Andrea S. , Linardi Valter R. 
Published: May 2003

AbstractIn this work, we show that the fungal strain Graphium sp. FIB4 was able to use phenol as the sole carbon source. Higher degradation of phenol was accomplished by alginate‐immobilized mycelial mass than by mycelial suspensions of Graphium sp. FIB4. Free mycelium exhibited higher degradation rates when compared with the alginate‐immobilized mycelium in the presence of 14 mM of phenol or less. Above this concentration, degradation rates by free mycelium decreased and the immobilized mycelium showed higher values. The maximum degradation rate for 8 mM phenol was found to be 20.13 mg/l × h by free mycelia and 16.24 mg/l × h by immobilized mycelial mass in the presence of 18 mM phenol. When the fungus was grown on medium without phenol, catechol 1,2‐dioxygenase activity was not detected. This enzyme activity was induced at phenol concentrations as low as 0.05 mM and up to 6 mM at 24 h incubation at 30 °C, suggesting that catechol was oxidized by the ortho type of ring fission. Addition of glucose reduced phenol consumption rate, and both substrates were used simultaneously. Glucose concentrations higher than 0.075% repressed the induction of phenol oxidation by Graphium sp. FIB4 grown on glucose. But glucose did not fully repress utilization of phenol by phenol‐pre‐induced cells. Immobilization and addition of calcium and barium ions were detrimental to the stability of catechol 1,2‐dioxygenase activity and phenol degradation by Graphium sp. FIB4.
Nucleotide sequence of MPB63 gene in Mycobacterium bovis BCG Tokyo
Authors: Kobayashi Kohmei , Kamiie Katsuyoshi , Kobayashi Akihiro , Matsuda Satoru 
Published: May 2003

AbstractMycobacterium bovis BCG has been used for the prevention of tuberculosis and as therapy for bladder tumor. MPB63 in M. bovis BCG is one of the immunogenic proteins and is secreted in large quantities. Therefore, it is of interest that the MPB63 gene be examined for the determination of its nucleotide sequence. A fragment of 820 base pairs (bp) including the MPB63 gene was prepared by amplification using polymerase chain reaction (PCR) employing M. bovis BCG Tokyo chromosomal DNA as a template and its nucleotide sequence was determined. The nucleotide sequence of mpb63 in M. bovis BCG was then compared with that of mpt63 in M. tuberculosis. The result indicated that the nucleotide sequences between two protein genes were quite agreeable in the genes' structural and upstream regions, except that one base change from C in mpt63 to G in mpb63 was detected in the downstream trailer sequence. This suggests that the genetic information of M. bovis BCG is not entirely identical to that of M. tuberculosis, although the characteristics of both microorganism are very similar to each other.
Chemical Modification of Chitosan, 17
Authors: Sashiwa Hitoshi , Yamamori Naoki , Ichinose Yoshifumi , Sunamoto Junzo , Aiba Sei‐ichi 
Published: May 2003

AbstractThe Michael reaction of chitosan with acrylic acid was carried out successfully, even in water alone as the reaction medium. As a consequence of its good solubility in water, the reaction product, N‐carboxyethylchitosan, showed excellent biodegradable properties with standard activated sludge.
magnified image
Laccase‐Catalyzed Oxidative Polymerization of Phenols
Authors: Mita Naruyoshi , Tawaki Shin‐ichiro , Uyama Hiroshi , Kobayashi Shiro 
Published: May 2003

AbstractLaccase‐catalyzed oxidative polymerization of phenol and its derivatives has been performed in aqueous organic solvents at room temperature in air. Laccase derived from Pycnoporus coccineus efficiently induced the polymerization to produce polyphenols consisting of a mixture of phenylene and oxyphenylene units. The unit ratio of the polymer could be precisely controlled by selection of the solvent and the monomer substituent.magnified image
Synthesis of Graft Bacterial Polyesters for Nanoparticles Preparation
Authors: Renard Estelle , Ternat Céline , Langlois Valérie , Guerin Philippe 
Published: May 2003

AbstractGraft copolymers of bacterial polyesters were prepared by direct condensation of poly(3‐hydroxyoctanoate‐co‐9‐carboxy‐3‐hydroxydecanoate) (PHOD) and poly(ethylene glycol) (PEG) or poly(lactic acid) (PLA). Nanoparticles from PHO, PHOD, PHOD‐g‐PEG, and PHOD‐g‐PLA were obtained by solvent displacement without stabilizer, and their stability in different aqueous media with different salt concentrations were studied. The results showed that the presence of hydrophilic PEG on the particle surface prevents the aggregation promotion by salts in aqueous solution. PHOD‐g‐PEG appears to be a promising candidate for site‐specific drug delivery systems.1H NMR spectrum of PHOD‐g‐PLA in CDCl3.magnified image1H NMR spectrum of PHOD‐g‐PLA in CDCl3.
Effect of Light Exposure on UV‐Vis Spectrum of [(nBuCp)2ZrCl2] Based Catalyst
Authors: Mäkelä‐Vaarne Nora I. , Kallio Kalle , Reichert Karl‐Heinz , Leskelä Markku A. 
Published: May 2003

AbstractUV‐vis spectroscopic study revealed that vinylcyclohexane interaction with zirconocene catalyst is enhanced on light exposure. If oxygen is present it interacts with the catalyst, hindering vinylcyclohexane interaction and consequently lowering the catalyst activity. The catalyst activity can be recovered with light exposure if low O2 concentrations are used since in light the zirconocene‐vinylcyclohexane interaction is favoured over the zirconocene‐O2 interaction. Moreover, 1H NMR studies of the reaction products showed that the structures of the vinylcyclohexane‐based species produced with light irradiation were identical to the species produced in dark. This indicates that light exposure of the catalytic system does not change the reaction mechanism.Absorption spectrum of [(nBuCp)2ZrCl2]/MAO/VCH. (a) reaction in dark, (b) reaction with irradiation, (c) reaction with O2 treatment in dark and (d) reaction with O2 treatment with irradiation.magnified imageAbsorption spectrum of [(nBuCp)2ZrCl2]/MAO/VCH. (a) reaction in dark, (b) reaction with irradiation, (c) reaction with O2 treatment in dark and (d) reaction with O2 treatment with irradiation.
Water‐Soluble Building Blocks for Terpyridine‐Containing Supramolecular Polymers: Synthesis, Complexation, and pH Stability Studies of Poly(ethylene oxide) Moieties
Authors: Lohmeijer Bas G. G. , Schubert Ulrich S. 
Published: May 2003

AbstractPoly(ethylene oxide) of various molecular weights (Mn = 3 000, 5 200, 10 000, 16 500 g · mol−1) has been modified with terpyridine end groups as building blocks for water‐soluble metallo‐supramolecular polymers. Metallo‐supramolecular A–A homopolymers have been prepared and characterized by complexing the terpyridine units of one selected poly(ethylene oxide) (Mn = 3 000 g · mol−1) with the following transition metal ions in their 2+ oxidation state: Fe, Ru, Co, Ni, Cu, Zn, and Cd. In addition, the stability of the supramolecular connection with respect to pH variations has been investigated.Schematic representation of the product of poly(ethylene oxide) modification with terpyridine end groups and the metal complexation.magnified imageSchematic representation of the product of poly(ethylene oxide) modification with terpyridine end groups and the metal complexation.
1H and 13C NMR Study of the Intermediates Formed by (Cp‐R)2ZrCl2 Activation with MAO and AlMe3/[CPh3][B(C6F5)4]. Correlation of Spectroscopic and Ethene Polymerization Data
Authors: Bryliakov Konstantin P. , Semikolenova Nina V. , Yudaev Dmitrii V. , Ystenes Martin , Rytter Erling , Zakharov Vladimir A. , Talsi Evgenii P. 
Published: May 2003

AbstractUsing 1H and 13C NMR spectroscopy, cationic intermediates formed by activation of (Cp‐R)2ZrCl2 (R = nBu, tBu and 1,2,3‐Me3) with MAO in toluene were monitored at Al/Zr ratios from 50 to 1 000. The catalysts (Cp‐R)2ZrCl2/AlMe3/CPh3+B(C6F5)4− (nBu, tBu and 1,2,3‐Me3) were also studied for comparison of spectroscopic and polymerization data with MAO based systems. Complexes of type (Cp‐R)2ZrMe+ ← Me−‐AlMAO (IV) with different Me‐MAO− counter anions have been identified in the (Cp‐R)2ZrCl2/MAO systems at low Al/Zr ratios. At Al/Zr ratios of 200–1 000, the complex [(Cp‐R)2Zr(μ‐Me)2AlMe2]+ Me‐MAO− (III) dominates in all MAO‐based reaction systems. Ethene polymerization activity strongly depends on the Al/Zr ratio (Al/Zr = 200–1 000) for the systems (Cp‐nBu)2ZrCl2/MAO and (Cp‐tBu)2ZrCl2/MAO, while it is virtually constant in the same range of Al/Zr ratios for the catalytic system (Cp‐1,2,3‐Me3)2ZrCl2/MAO. The data obtained are interpreted on the assumption that complex III is the actual precursor of active centers of polymerization in MAO based systems.Formation of cationic intermediates by activation with MAO.magnified imageFormation of cationic intermediates by activation with MAO.
Functionalization of LDPE by Melt Grafting with Glycidyl Methacrylate and Reactive Blending with Polyamide‐6
Authors: Wei Qian , Chionna Donatella , Galoppini Elena , Pracella Mariano 
Published: May 2003

AbstractLow‐density polyethylene (LDPE) was functionalized by melt radical grafting with glycidyl methacrylate (GMA) and employed for reactive blending with polyamide‐6 (PA6). The effect of the reaction procedure on the grafting degree of LDPE‐g‐GMA samples (0.5–12.5 wt.‐% GMA) was analyzed as a function of the concentration of GMA monomer, radical initiator (BTP), and addition of styrene as co‐monomer. Optimized grafting conditions were obtained when the amount of the monomer is below 10 wt.‐% and that of peroxide in the range 0.2–0.4 wt.‐%. Binary blends of PA6 with LDPE‐g‐GMA (3.5 wt.‐% GMA) and with LDPE at various compositions (80/20, 67/33, 50/50 wt.‐%) were prepared in an internal mixer and their properties were evaluated by torque, SEM and DSC analyses. Morphological examination by SEM showed a large improvement of phase dispersion and interfacial adhesion in PA6/LDPE‐g‐GMA blends as compared with PA6/LDPE blends. The average diameter of dispersed polyolefin particles was about 0.4 μm for LDPE‐g‐GMA contents < 50 wt.‐%. A marked increase of melt viscosity was observed for the compatibilized blends depending on the concentration of grafted polyolefin, and it was accounted for by the reaction between the epoxy groups of GMA and the carboxyl/amine end‐groups of PA6. The variation of torque was thus related to the molar ratio of reactive group concentration. The analysis of crystallization and melting behavior pointed out marked differences in the phase structure of the blends due to the presence of the functionalized polyolefin. Finally, the in situ formation of a graft copolymer between LDPE‐g‐GMA and PA6 was investigated by means of a selective dissolution method (Molau test) and by FT‐IR and DSC analyses.SEM micrograph of fracture surface of PA6/LDPE‐g‐GMA 50/50 blend.magnified imageSEM micrograph of fracture surface of PA6/LDPE‐g‐GMA 50/50 blend.
A splitting theorem for the Medvedev and Muchnik lattices
Authors: Binns Stephen 
Published: May 2003

AbstractThis is a contribution to the study of the Muchnik and Medvedev lattices of non‐empty Π01 subsets of 2ω. In both these lattices, any non‐minimum element can be split, i. e. it is the non‐trivial join of two other elements. In fact, in the Medvedev case, ifP > M Q, then P can be split above Q. Both of these facts are then generalised to the embedding of arbitrary finite distributive lattices. A consequence of this is that both lattices have decidible ∃‐theories.
Negation and BCK‐algebras
Authors: García Olmedo Francisco M. , Rodríguez Salas Antonio J. 
Published: May 2003

AbstractIn this paper we consider twelve classical laws of negation and study their relations in the context of BCK‐algebras. A classification of the laws of negation is established and some characterizations are obtained. For example, using the concept of translation we obtain some characterizations of Hilbert algebras and commutative BCK‐algebras with minimum. As a consequence we obtain a theorem relating those algebras to Boolean algebras.
Categorical abstract algebraic logic: The criterion for deductive equivalence
Authors: Voutsadakis George 
Published: May 2003

AbstractEquivalent deductive systems were introduced in [4] with the goal of treating 1‐deductive systems and algebraic 2‐deductive systems in a uniform way. Results of [3], appropriately translated and strengthened, show that two deductive systems over the same language type are equivalent if and only if their lattices of theories are isomorphic via an isomorphism that commutes with substitutions. Deductive equivalence of π‐institutions [14, 15] generalizes the notion of equivalence of deductive systems. In [15, Theorem 10.26] this criterion for the equivalence of deductive systems was generalized to a criterion for the deductive equivalence of term π‐institutions, forming a subclass of all π‐institutions that contains those π‐institutions directly corresponding to deductive systems. This criterion is generalized here to cover the case of arbitrary π‐institutions.
Generic separations and leaf languages
Authors: Galota Matthias , Kosub Sven , Vollmer Heribert 
Published: May 2003

AbstractIn the early nineties of the previous century, leaf languages were introduced as a means for the uniform characterization of many complexity classes, mainly in the range between P (polynomial time) and PSPACE (polynomial space). It was shown that the separability of two complexity classes can be reduced to a combinatorial property of the corresponding defining leaf languages. In the present paper, it is shown that every separation obtained in this way holds for every generic oracle in the sense of Blum and Impagliazzo. We obtain several consequences of this result, regarding, e. g., universal oracles, simultaneous separations and type‐2 complexity.
Expanding the additive reduct of a model of Peano arithmetic
Authors: Murakami Masahiko , Tsuboi Akito 
Published: May 2003

AbstractLet M be a model of first order Peano arithmetic (PA) and I an initial segment of M that is closed under multiplication. LetM0 be the {0, 1,+}‐reduct ofM. We show that there is another model N of PA that is also an expansion of M0 such that a · M a = a · N a if and only if a ∈ I for all a ∈ M.
Some weak forms of the Baire category theorem
Authors: Kermedis Kyriakos 
Published: May 2003

AbstractWe show that the statement (K12) “separable, countably compact, regular spaces are Baire” is deducible from a strictly weaker form than AC, namely, CAC(ℝ) (the axiom of choice for countable families of non‐empty subsets of the real line ℝ). We also find some characterizations of the axiom of dependent choices.
Characterizing strong compactness via strongness
Authors: Apter Arthur W. 
Published: May 2003

AbstractWe construct a model in which the strongly compact cardinals can be non‐trivially characterized via the statement “κ is strongly compact iff κ is a measurable limit of strong cardinals”. If our ground model contains large enough cardinals, there will be supercompact cardinals in the universe containing this characterization of the strongly compact cardinals.
Arithmetical definability over finite structures
Authors: Lee Troy 
Published: May 2003

AbstractArithmetical definability has been extensively studied over the natural numbers. In this paper, we take up the study of arithmetical definability over finite structures, motivated by the correspondence between uniform AC0and FO(PLUS, TIMES). We prove finite analogs of three classic results in arithmetical definability, namely that < and TIMES can first‐order define PLUS, that < and DIVIDES can first‐order define TIMES, and that < and COPRIME can first‐order define TIMES. The first result sharpens the equivalence FO(PLUS, TIMES) =FO(BIT) to FO(<, TIMES) = FO(BIT), answering a question raised by Barrington et al. about the Crane Beach Conjecture. Together with previous results on the Crane Beach Conjecture, our results imply that FO(PLUS) is strictly less expressive than FO(<, TIMES) = FO(<, DIVIDES) = FO(<,COPRIME). In more colorful language, one could say that, for parallel computation, multiplication is harder than addition.
ω‐categorical weakly o‐minimal expansions of Boolean lattices
Authors: Leonesi Stefano , Toffalori Carlo 
Published: May 2003

AbstractWe study ω‐categorical weakly o‐minimal expansions of Boolean lattices. We show that a structure 𝒜 = (A,≤, ℐ) expanding a Boolean lattice (A,≤) by a finite sequence I of ideals of A closed under the usual Heyting algebra operations is weakly o‐minimal if and only if it is ω‐categorical, and hence if and only if A/I has only finitely many atoms for every I ∈ ℐ. We propose other related examples of weakly o‐minimal ω‐categorical models in this framework, and we examine the internal structure of these models.
On semilattice relevant logics
Authors: Kashima Ryo 
Published: May 2003

AbstractThe semilattice relevant logics ∪R, ∪T, ∪RW, and ∪TW (slightly different from the orthodox relevant logics R, T, RW, and TW) are defined by semilattice models in which conjunction and disjunction are interpreted in a natural way. For each of them, there is a cut‐free labelled sequent calculus with plural succedents (like LK). We prove that these systems are equivalent, with respect to provable formulas, to the restricted systems with single succedents (like LJ). Moreover, using this equivalence, we give a new Hilbert‐style axiomatizations for ∪R and ∪T and prove equivalence between two semantics (commutative monoid and distributive semilattice) for the contractionless logics ∪RW and ∪TW.
A probabilistic extension of intuitionistic logic
Authors: Marković Zoran , Ognjanović Zoran , Rašković Miodrag 
Published: May 2003

AbstractWe introduce a probabilistic extension of propositional intuitionistic logic. The logic allows making statements such as P≥sα, with the intended meaning “the probability of truthfulness of α is at least s”. We describe the corresponding class of models, which are Kripke models with a naturally arising notion of probability, and give a sound and complete infinitary axiomatic system. We prove that the logic is decidable.
On two questions about feasibly constructive arithmetic
Authors: Moniri Morteza 
Published: May 2003

AbstractIPV is the intuitionistic theory axiomatized by Cook's equational theory PV plus PIND on NP‐formulas. Two extensions of IPV were introduced by Buss and by Cook and Urquhart by adding PIND for formulas of the form A(x) ∨ B, respectively ¬¬A(x), where A(x) is NP and x is not free in B. Cook and Urquhart posed the question of whether these extensions are proper. We show that in each of the two cases the extension is proper unless the polynomial hierarchy collapses.
The discrete parts of approximately decidable sets in Euclidean spaces
Authors: Hemmerling Armin 
Published: May 2003

AbstractIt is shown that the classes of discrete parts, A ∩ ℕk, of approximately resp. weakly decidable subsets of Euclidean spaces, A ⊆ ℝk, coincide and are equal to the class of ω‐r. e. sets which is well‐known as the first transfinite level in Ershov's hierarchy exhausting Δ02.
Biospecific Properties of Random Copolymers, 2
Authors: Bouzou Bérengère , Pflüger Fernando 
Published: May 2003

AbstractPrevious results obtained have shown that it was possible to create biospecific sites onto polymers through statistic modifications of polystyrene derivatives copolymer with given chemical groups or through synthesis of random methacrylate‐based copolymers. Such polymers show biological activities (anticoagulant, cell proliferation modulation …) dependent of the global composition and thus of the statistical distribution of the functional groups, and the number of biospecific sites is simply correlated to the observed biological activity. The study of the radical terpolymerization allows us to use a Monte Carlo based synthesis simulation and to determine the occurrence frequency of three to twenty monomers sequences as a function of the conversion rate and the global composition. The comparison of the sequences occurrence curves as a function of the global composition of the polymers with the experimental cell proliferation inhibition curve led us to extract a series of eight monomers sequences with similar structure properties representing a group of biospecific sites responsible for the observed biological activity.Radical terpolymerization of MMA, MA, and NaSS in DMSO initiated by AIBN.imageRadical terpolymerization of MMA, MA, and NaSS in DMSO initiated by AIBN.
Mesophase Formation in Solutions of Diblock Copolymers Simulated Using the Bond Fluctuation Model
Authors: Freire Juan J. , McBride Carl 
Published: May 2003

AbstractThe behavior of symmetric diblock copolymer chains of two different lengths at different concentrations is simulated by means of the bond fluctuation model. Two alternative sets of energies between interacting neighbors are proposed. In one of the sets, attractions between monomers of the same type are considered. In the other set, repulsions between monomers of different types are considered. The collective scattering of the simulation boxes is computed for different values of the reduced energy interaction parameter and the total polymer volume fraction. The analysis of this property is used to locate the transition associated with the formation of mesophases (lamellae) as a function of these two variables. A comparison between the results corresponding to the two different models is performed. When the significant excluded volume corrections are introduced in the model with repulsive interactions, both sets of data agree, except for the most dilute samples. The agreement with the self‐consistent field theory is only fair, and important differences are observed in the intermediate concentration regime. These differences were expected, since the theoretical treatment is only rigorously valid for very long chains.Comparison of the simulation data for the transition points with the prediction of the self‐consistent field theory (solid line).imageComparison of the simulation data for the transition points with the prediction of the self‐consistent field theory (solid line).