Mapping the Wigner distribution function of the Morse oscillator onto a semiclassical distribution function

The mapping of the Wigner distribution function (WDF) for a given bound state onto a semiclassical distribution function (SDF) satisfying the Liouville equation introduced previously by us is applied to the ground state of the Morse oscillator. The purpose of the present work is to obtain values of the potential parameters represented by the number of levels in the case of the Morse oscillator, for which the SDF becomes a faithful approximation of the corresponding WDF. We find that for a Morse oscillator with one level only, the agreement between the WDF and the mapped SDF is very poor but for a Morse oscillator of ten levels it becomes satisfactory. We also discuss the limit h --> 0 for fixed potential parameters.

Low-energy muon-transfer reaction from hydrogen isotopes to helium isotopes

Direct muon transfer in low-energy collisions of the muonic hydrogen H-mu and helium (He++) is considered in a three-body quantum-mechanical framework of coordinate-space integro-differential Faddeev-Hahn-type equations within two- and six-state close coupling approximations. The final-state Coulomb interaction is treated without any approximation employing appropriate Coulomb waves in the final state. This procedure of treating Coulomb interaction leads to much improved results for low-energy transfer rates. The present results agree reasonably well with previous semiclassical calculations. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Synthesis, characterization and catalytic properties of nanocrystaline Y2O3-coated TiO2 in the ethanol dehydration reaction

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Classes of exact Klein-Gordon equations with spatially dependent masses: Regularizing the one-dimensional inversely linear potential

In this work we consider the effect of a spatially dependent mass over the solution of the Klein-Gordon equation in 1 + 1 dimensions, particularly the case of inversely linear scalar potential, which usually presents problems of divergence of the ground-state wave function at the origin, and possible nonexistence of the even-parity wave functions. Here we study this problem, showing that for a certain dependence of the mass with respect to the coordinate, this problem disappears. (c) 2006 Elsevier B.V. All rights reserved.

Detection and differentiation of Leptospira spp. serovars in bovine semen by polymerase chain reaction and restriction fragment length polymorphism

In view of the importance of venereal transmission of bovine leptospirosis, the objective of the present study was to apply the polymerase chain reaction (PCR) to 26 serovars of Leptospira interrogans, L. borgpetersenii, L. santarosai, L. noguchii and L. biflexa, to determine the detection threshold in semen samples and to evaluate the possibility of differentiation among serovars using 19 restriction endonucleases. The results showed that all serovars were amplified and the detection threshold in semen samples of a bull was 100 bacteria/ml. Using endonucleases we could classify the 26 serovars into eight groups. The present results show that PCR is a method of great potential for the detection of Leptospira spp, at bovine artificial insemination centers. (C) 2000 Elsevier B.V. B.V. All rights reserved.

Mechanistic insights into the reaction between VO2+ and propene based on a DFT study

Calculations based on density functional theory have been carried out to investigate the free energy profiles at singlet and triplet electronic states associated with the gas-phase ion/molecule reactions of VO2++ ((1)A(1)/(3)A) with propene. The complex potential energy Surfaces, including Six reaction pathways (three dehydrogenation and three oxygen transfer processes), have been explored and analyzed. Along dehydrogenation reactive channels, three final products can be obtained: V(OH)(2)(+) ((1)Sigma(+)/(3)Sigma(-)) and allene (path Dehl), being the most kinetically and thermodynamically favorable reaction pathway, V(OH)(2)(+) ((1)Sigma(+)/(3)Sigma(-)) and propyne (path Deh2),and VO2+ ((1)A(1)/(3)A) and H-2 plus allene (path Deh3). The oxyoenation processes can yield its final products Vo(+) ((1)Delta/(3)Sigma) and acetone (path Ox1), VO+ ((1)Delta/(3)Sigma 2) and propanaldehyde (path Ox2), and VO+ ((1)Delta/(3)Sigma) and H-2 and propenaldehyde (path Ox3). Both paths Deh1 and Deh2 are associated with two consecutive hydrogen transfer processes from carbon atoms of the propene fragment to vanadyl oxygen atoms, while in path Deh3 the second hydrogen migration takes place to the vanadiurn atorn followed by the formation ola hydrogen molecule. Both paths Ox1 and Ox2 comprise an intramolecular hydrogen transfer between the ethylenic moiety of the propene fragment, while two consecutive hydrogen transfer processes take place from the propene fragment to oxygen and vanadium atoms of the vanadyl moiety along path Ox3. Three crossing points between both electronic states take place along path Deh1 (CP-Deh1) and path Deh2 (CP-Deh2) and in the entrance channel of oxidation processes (CP-Ox). A comparison with previous works on related reactions VO2+ + C2H4, VO2 + C2H6, and VO2+ + C3H8 allows us to rationalize the different reactivity patterns.

SURFACE EFFECTS IN THE HYDROGEN EVOLUTION REACTION ON NI-ZN ALLOY ELECTRODES IN ALKALINE-SOLUTIONS

Hydrogen evolution reaction was studied on Ni-Zn (25% of Ni before leaching) in 1 M NaOH at 25 degrees C. These electrodes were characterized by very low Tafel slopes of 67 mV dec(-1). Other techniques used included potential and current pulse, potential relaxation in an open circuit, and ac impedance spectroscopy. Analysis of the experimental results led to the conclusion that hydrogen adsorption in the surface layers was responsible for the observed behavior. Influence of the oxidation of the electrode surface and the addition of poisons, thiourea and cyanides, were also studied. These processes inhibit the hydrogen absorption and restore ''normal'' Tafel slopes. Kinetic parameters of the hydrogen evolution reaction were determined.

DFT study of the reaction between VO2+ and C2H6

The molecular mechanisms of the reaction VO2+ ((1)A(1)/(3)A'') + C2H6 ((1)A(g)) to yield V(OH)(2)(+) ((1)Sigma(+)/(3)Sigma(-)) + C2H4 ((1)A(g)) and/or VO+ ((1)Delta/(3)Sigma) + H2O ((1)A(1)) + C2H4 (Ag-1) have been investigated with density functional theory (DFT) at the B3LYP/6-311G(2d,p) level. Calculations including geometry optimization, vibrational analysis, and Gibbs free energy for the stationary points on the reactive potential energy surfaces at both the singlet (s) and first excited triplet (t) electronic states have been carried out. The most thermodynamically and kinetically favorable pathway is the formation of t-V(OH)(2)(+) + C2H4 along a four-step molecular mechanism (insertion, two consecutive hydrogen transfers, and elimination). A crossing point between s and t electronic states has been characterized. A comparison with previous works on VO2+ + C2H4 (Gracia et al. J. Phys. Chem. A 2003, 107, 3107-3120) and VO2+ + C3H8 (Engeser et al. Organometallics 2003, 22, 3933-3943) reactions allows us a rationalization of the different reactivity patterns. The catalytic role of water molecules in the tautomerization process between hydrated oxide cation, VO(H2O)(+,) and dihydroxide cation, V(OH)(2)(+), is achieved by a water-assisted mechanism.

Purine nucleoside phosphorylase: A potential target for the development of drugs to treat T-cell- and apicomplexan parasite-mediated diseases

Purine nucleoside phosphorylase (PNP) catalyzes the reversible phosphorolysis of nucleosides and deoxynucleosides, generating ribose 1-phosphate and the purine base, which is an important step of purine catabolism pathway. The lack of such an activity in humans, owing to a genetic disorder, causes T-cell impairment, and thus drugs that inhibit human PNP activity have the potential of being utilized as modulators of the immunological system to treat leukemia, autoimmune diseases, and rejection in organ transplantation. Besides, the purine salvage pathway is the only possible way for apicomplexan parasites to obtain the building blocks for RNA and DNA synthesis, which makes PNP from these parasites an attractive target for drug development against diseases such as malaria. Hence, a number of research groups have made efforts to elucidate the mechanism of action of PNP based on structural and kinetic studies. It is conceivable that the mechanism may be different for PNPs from diverse sources, and influenced by the oligomeric state of the enzyme in solution. Furthermore, distinct transition state structures can make possible the rational design of specific inhibitors for human and apicomplexan enzymes. Here, we review the current status of these research efforts to elucidate the mechanism of PNP-catalyzed chemical reaction, focusing on the mammalian and Plamodium falciparum enzymes, targets for drug development against, respectively, T-Cell and Apicomplexan parasites-mediated diseases.

Platinum surface modification with cerium species and the effect against the methanol anodic reaction

Spontaneous deposition and electrochemical deposition by potential perturbation programs were used to place cerium-containing species on platinum surfaces in acid solution. Cyclic voltammetric profiles of cerium-modified platinum surfaces obtained after potentiostatic or potentiodynamic procedures (applied in the true hydrogen evolution region) differ from those recorded after spontaneous methods. However, the catalytic effects are nearly the same on these cerium-modified platinum surfaces for methanol electrooxidation, i.e. lower onset potential values for the anodic reaction. Besides, a different electrocatalytic effect was observed at large positive potentials on methanol oxidation due to the cerium oxide capability of oxygen storage. This effect is observed on platinum modified by a drastic potentiostatic procedure (by applying -2.0 V) in cerium(IV) acid solution. (C) 2008 Elsevier B.V. All rights reserved.

Theoretical study on the reaction mechanism of VO2+ with propyne in gas phase

Possible molecular mechanisms of the gas-phase ion/molecule reaction of VO2+ in its lowest singlet and triplet states ((1)A(1)/(3)A '') with propyne have been investigated theoretically by density functional theory (DFT) methods. The geometries, energetic values, and bonding features of all stationary and intersystem crossing points involved in the five different reaction pathways (paths 1-5), in both high-spin (triplet) and low-spin (singlet) surfaces, are reported and analyzed. The oxidation reaction starts by a hydrogen transfer from propyne molecule to the vanadyl complex, followed by oxygen migration to the hydrocarbon moiety. A hydride transfer process to the vanadium atom opens four different reaction courses, paths 1-4, while path 5 arises from a hydrogen transfer process to the hydroxyl group. Five crossing points between high- and low-spin states are found: one of them takes place before the first branching point, while the others occur along path 1. Four different exit channels are found: elimination of hydrogen molecule to yield propynaldehyde and VO+ ((1)Sigma/(3)Sigma); formation of propynaldehyde and the moiety V-(OH2)(+); and two elimination processes of water molecule to yield cationic products, Prod-fc(+) and Prod-dc(+) where the vanadium atom adopts a four- and di-coordinate structure, respectively.

Detection of leptospires in bovine semen by polymerase chain reaction

Objective: In view of the considerable importance of venereal transmission of bovine leptospirosis, the objective of the present study was to compare the polymerase chain reaction (PCR), culture/isolation and serology to detect leptospire infection in bovine semen. Design: Blood for serologic examination and semen for bacterial culture and PCR were collected from 20 bulls at artificial insemination centres in Brazil. Each animal was sampled twice for serology. Result: Forty-five percent (9/20) of the serum samples collected showed agglutinin titers to serovar hardjo in the first sample and 25% (5/20) had agglutinin titers to serovar hardjo in the second sample. Eighty percent (16/20) of semen samples were positive by PCR. Leptospires could not be isolated from any of the semen samples examined. Conclusion: Polymerase chain reaction can be a method of great potential for the detection of leptospires at artificial insemination centres.

Voltammetric Study of a Cubic Silsesquioxane Organically Modified with Imidazole and their Subsequent Reaction with Cadmium and Hexacyanoferrate (III)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

An Integrative Genomic and Transcriptomic Analysis Reveals Potential Targets Associated with Cell Proliferation in Uterine Leiomyomas

Background: Uterine Leiomyomas (ULs) are the most common benign tumours affecting women of reproductive age. ULs represent a major problem in public health, as they are the main indication for hysterectomy. Approximately 40-50% of ULs have non-random cytogenetic abnormalities, and half of ULs may have copy number alterations (CNAs). Gene expression microarrays studies have demonstrated that cell proliferation genes act in response to growth factors and steroids. However, only a few genes mapping to CNAs regions were found to be associated with ULs. Methodology: We applied an integrative analysis using genomic and transcriptomic data to identify the pathways and molecular markers associated with ULs. Fifty-one fresh frozen specimens were evaluated by array CGH (JISTIC) and gene expression microarrays (SAM). The CONEXIC algorithm was applied to integrate the data. Principal Findings: The integrated analysis identified the top 30 significant genes (P<0.01), which comprised genes associated with cancer, whereas the protein-protein interaction analysis indicated a strong association between FANCA and BRCA1. Functional in silico analysis revealed target molecules for drugs involved in cell proliferation, including FGFR1 and IGFBP5. Transcriptional and protein analyses showed that FGFR1 (P = 0.006 and P<0.01, respectively) and IGFBP5 (P = 0.0002 and P = 0.006, respectively) were up-regulated in the tumours when compared with the adjacent normal myometrium. Conclusions: The integrative genomic and transcriptomic approach indicated that FGFR1 and IGFBP5 amplification, as well as the consequent up-regulation of the protein products, plays an important role in the aetiology of ULs and thus provides data for potential drug therapies development to target genes associated with cellular proliferation in ULs. © 2013 Cirilo et al.

Identification of blood meal sources of Lutzomyia longipalpis using polymerase chain reaction-restriction fragment length polymorphism analysis of the cytochrome B gene

An analysis of the dietary content of haematophagous insects can provide important information about the transmission networks of certain zoonoses. The present study evaluated the potential of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the mitochondrial cytochrome B (cytb)gene to differentiate between vertebrate species that were identified as possible sources of sandfly meals. The complete cytb gene sequences of 11 vertebrate species available in the National Center for Biotechnology Information database were digested with Aci I, Alu I, Hae III and Rsa I restriction enzymes in silico using Restriction Mapper software. The cytb gene fragment (358 bp) was amplified from tissue samples of vertebrate species and the dietary contents of sandflies and digested with restriction enzymes. Vertebrate species presented a restriction fragment profile that differed from that of other species, with the exception of Canis familiaris and Cerdocyon thous. The 358 bp fragment was identified in 76 sandflies. Of these, 10 were evaluated using the restriction enzymes and the food sources were predicted for four: Homo sapiens (1), Bos taurus (1) and Equus caballus (2). Thus, the PCR-RFLP technique could be a potential method for identifying the food sources of arthropods. However, some points must be clarified regarding the applicability of the method, such as the extent of DNA degradation through intestinal digestion, the potential for multiple sources of blood meals and the need for greater knowledge regarding intraspecific variations in mtDNA.