The higher grading structure of the WKI hierarchy and the two-component short pulse equation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influence of N-Terminus Modifications on the Biological Activity, Membrane Interaction, and Secondary Structure of the Antimicrobial Peptide Hylin-a1

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

Carbon sources and trophic position of the main species of fishes of Baía River, Paraná River floodplain, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Electrolocation-communication discharges of the fish Gymnotus carapo L. (Gymnotidae: Gymnotiformes) during behavioral sleep

Technical problems have hampered the study of sleep in teleosts. The electrical discharges of Gymnotus carapo L. (Gymnotidae: Gymnotiformes) were monitored to evaluate their ease and reliability as parameters to study sleep. The discharges were detected by electrodes immersed in a glass aquarium and were recorded on a conventional polygraph. G. carapo showed conspicuous signs of behavioral sleep. During these periods, opercular beat rates were counted, electric discharges recorded, and the sharp discharge increase (SDI) of the orienting reflex was investigated. All 20 animals monitored maintained electrical discharges during behavioral sleep. The discharge frequencies during sleep (50.3 ± 10.4 Hz) were not significantly different from those observed when the fish was awake and inactive (57.2 ± 12.1 Hz) (Wilcoxon matched-pairs signed-ranks test, P>0.05). However, the SDI, which was prevalent in the awake fish, was not observed during periods of behavioral sleep. Additional observations showed that the species had cannibalistic habits. When presented with electrical discharges from a conspecific, the sleeping fish showed an initial decrease or pause in discharge frequency, while the awake fish did not have this response. We conclude that the electrical discharges of G. carapo were not conspicuous indicators of behavioral sleep. Discharges may have been maintained during sleep for sensory purposes, i.e., conspecific detection and avoidance of cannibalistic attacks.

The Gerasimov-Drell-Hearn Sum Rule and the Spin Structure of the Proton

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

STRUCTURE OF THE RETE TESTIS OF THE CAT (FELIS-DOMESTICA, L)

The rete testis of the cat consists of 3 parts: a septal or interlobular part; a mediastinal part and a tunical part. The septal part contains the septal or transitory tubuli recti and the tubuli recti. The transitory tubules are formed as a confluence of the seminiferous tubules at the apex of the testicular lobules and the tubuli recti. The mediastinal rete is formed of long, straight channels which increase in size and become more irregular and anastomotic below the tunica albuginea at the cranial extremity of the testis. The end is characterized as the tunical part of the rete testis and communicates with the extratesticular rete testis. The channels all parts of the rete are lined by simple cuboidal or columnar epithelium. These epithelial channels are supported by a connective tissue containing smooth muscle cells. The framework tissue of the rete is more conspicuous at the cranial extremity of the testis, with a mio-connective matrix organization.

A theoretical analysis on electronic structure of the (110) surface of TiO2-SnO2 mixed oxide

Mixed oxide compounds, such as TiO2-SnO2 system are widely used as gas sensors and should also provide varistor properties modifying the TiO2 surface. Therefore, a theoretical investigation has been carried out characterizing the effect of SnO2 on TiO2 addition on the electronic structure by means of ab initio SCF-LCAO calculations using all electrons. In order to take into account the finite size of the cluster, we have used the point charge model for the (TiO2)(15) cluster to study the effect on electronic structure of doping the TiO2 (110) Surface. The contracted basis set for titanium (4322/42/3), oxygen (33/3) and tin (43333/4333/43) atoms were used. The charge distributions, dipole moments, and density of states of doping TiO2 and vacancy formation are reported and analysed. (C) 2003 Elsevier B.V. All rights reserved.

Effect of the temperature on the TMOS sono-hydrolysis and a study of the structure of the resulting aged sonogels

The effect of temperature on the oxalic acid catalyzed sono-hydrolysis of tetramethoxysilane (TMOS) was studied by means of a heat flux calorimetric method. The activation energy of the process was measured as (24.5 +/- 0.8) kJ/mol in the temperature range between 10 and 50 degreesC. The structural characteristics of the resulting sonogels, after long period of aging in saturated conditions, were studied by means of small angle X-ray scattering. The structure can be described as formed by similar to2.7 nm mean size mass fractal-like aggregates (clusters) of primary silica particles of similar to0.3 nm mean size, all imbibed in a liquid phase. The average mass fractal dimension of the clusters was found to be 2.58. The primary particle density was estimated as 2.23 g/cm(3), in good agreement with the value frequently quoted for fused silica. The volume fraction of the clusters, in the saturated sonogels was estimated as about 28%. The moment in which the meniscus of the liquid phase penetrates into the clusters under rapid evaporation process has been detected by an inflection in the first derivative of the curve of weight loss in a simple thermogravimetric test. (C) 2003 Elsevier B.V. All rights reserved.

AN INVESTIGATION OF THE ELECTRONIC-STRUCTURE OF THE ANTITUMOR DRUG ELLIPTICINE AND ITS DERIVATIVES .1. GEOMETRICAL AM1 STUDY

Ellipticine and its derivatives are a class of molecules that show antitumor and cytotoxic activity with a multimodal mechanism of action. In this paper we report a preliminary Austin Method One (AM1) study of ellipticine and some molecules derived from it. We have observed a relationship between charge density distribution and biological selectivity. A mechanism that could improve cytotoxic activity is proposed.

Synthesis and X-ray structure of the dinuclear platinum(II) complex with saccharin {K[Pt(sac)(3)(H2O)] center dot H2O}(2): Studies on its antiproliferative activity in aqueous solution

Synthesis and X-ray structure of a dinuclear platinum(II) complex with the ligand saccharin(sac) are described. The structure shows two approximately square-planar platinum centers. Each platinum atom is coordinated to one water molecule and three N-bonded saccharinate ligands. The two centers are linked through two potassium atoms. Each potassium atom interacts with six oxygen atoms from hydration and coordinated water molecules and from carbonyl and sulfonate groups of the ligands. It is suggested that, in aqueous solution, the dimeric structure of the complex is dissociated and the monomeric species K[Pt(sac)(3)(H2O)] is formed. The complex was dissolved in water and submitted to in vitro cytotoxic analyses using HeLa cells (human cervix cancer). It was shown that the monomeric complex elicited a potent cytotoxic activity when compared to the vehicle-treated cells. The IC50 value for the monomeric complex is 6.8 mu M, a little bit higher than that obtained for cisplatin. (c) 2007 Elsevier B.V. All rights reserved.

DECIPHERING THE QUARK-GLUON STRUCTURE OF THE PHOTON IN E-GAMMA COLLISIONS

We investigate the capability of an egamma collider to unravel the hadronic content of the photon. The experimental problem for probing the gluonic structure of the photon is that small-x triggers overwhelmingly select soft photons rather than soft gluons in hard photons. We show that the problem can be finessed in experiments where laser back-scattering is used to prepare a source of very hard photons. We illustrate their power for studying the parton distributions of the photon and, specifically, for separating the quark and gluon components in events where dijets, jet-gamma pairs, and heavy quark pairs are produced.

Jahn-Teller effect on the structure of the Sm-doped PbTiO3: A theoretical approach

Samarium doped PbTiO3 (PT:Sm) and pure PbTiO3 (PT) powders were obtained by polymeric precursor method. These powders were characterized by X-ray diffraction (XRD) and theoretical calculations using the CRYSTAL98 program. The effect of the samarium atom is taken into account only indirectly. The experimental models were compared with the cubic (ideal) and tetragonal theoretical models. The structure deformations existent in the experimental compounds were analyzed from the tiny structural differences that lead to perturbations in the crystal orbital splittings. This paper proposes an efficient alternative methodology for defining structural distortions. (c) 2007 Elsevier B.V. All rights reserved.