Resistive-Switching Behavior in Polycrystalline CaCu3Ti4O12 Nanorods

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

Nonlinear electrical behaviour of the Cr2O3, ZnO, CoO and Ta2O5-doped SnO2 varistors

The effects of Cr2O3 on the properties of (Zn, Co, Ta)-doped SnO2 varistors were investigated in this study. The samples with different Cr2O3 concentrations were sintered at 1400 degrees C for 2 h. The properties of (Zn, Co, Ta, Cr)-doped SnO2 varistors were evaluated by XRD. dilatornetry, SEM, I-V and impedance spectroscopy. DC electrical characterization showed a dramatic increase ill the breakdown electrical field and in the nonlinear coefficient with the increase in Cr2O3 concentration. The grain size was found to decrease from 13 to 5 mu m with increasing the Cr2O3 content. The impedance data, represented by means of Nyquist diagrams, show two time constants, one at low frequencies and the other at high frequencies. (c) 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Dependence of La2O3 content on the nonlinear electrical behaviour of ZnO, CoO and Ta2O5 doped SnO2 varistors

The effects of La2O3 on the properties of (Zn, Co, Ta) doped SnO2 varistors were investigated in this study. The samples with different La2O3 concentrations were sintered at 1400 degrees C for 2 h and their properties were characterized by XRD, SEM, I-V and impedance spectroscopy. The grain size was found to decrease from 13 pm to 9 gm with increasing La2O3 content. The addition of rare earth element leads to increase the nonlinear coefficient and the breakdown voltage. The enhancement was expected to arise from the possible segregation of lanthanide ion due to its larger ionic radius to the grain boundaries, thereby modifying its electrical characteristics. Furthermore, the dopants such as La may help in the adsorption of O' to O '' at the grain boundaries characteristics. (c) 2006 Elsevier B.V. All rights reserved.

Relaxation-chaos phenomena in celestial mechanics. I. On wisdom's model for the 3/1 kirkwood gap

Sudden eccentricity increases of asteroidal motion in 3/1 resonance with Jupiter were discovered and explained by J. Wisdom through the occurrence of jumps in the action corresponding to the critical angle (resonant combination of the mean motions). We pursue some aspects of this mechanism, which could be termed relaxation-chaos: that is, an unconventional form of homoclinic behavior arising in perturbed integrable Hamiltonian systems for which the KAM theorem hypothesis do not hold. © 1987.

Effects of Spider Venom Toxin PWTX-I (6-Hydroxytrypargine) on the Central Nervous System of Rats

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

Arrays of gold microelectrodes made from split integrated circuit chips

A simple and inexpensive way to fabricate arrays of gold microelectrodes is proposed. Integrated circuit chips are sawed through their middle, normal to the longest axis, leading to destruction of the silicon circuit and rupture of the gold wires that interconnect it with the external terminals. Polishing the resulting rough surface converts the tips of the wires embedded in the chip halves into arrays of gold microdisks of about 25 mu m diameter. The number of active microelectrodes (MEs), of an array depends on the number of pins in the chip, n, being typically (n/2)-4. These MEs can be used individually or externally interconnected in any combination. X-ray images of the chips and micrographs of the resulting surface of the polished arrays have revealed variable distances between neighbor MEs, which are, however, larger than 10 times the radius of the disks. This feature of the MEs prevents diffusional cross-talk between electrodes. The use of these microdisk electrodes for analytical purposes exhibits sigmoidal voltammograms, and chronoamperometric experiments confirm the nonlinear i vs. t(1/2) plots, typical for processes where radial diffusion prevails. Satisfactory uniformity was observed for the response of each electrode of an array, indicating similarity of geometry and disk areas. The potentialities of these MEs were demonstrated by the determination of cadmium at ppb levels using square wave voltammetry with preconcentration. Due to the relative ease with which these MEs can be manufactured and their good performance in (chemical) analysis, wide applications in electrochemistry and electroanalysis is envisioned.

Study of stayability in Nellore cows using a threshold model

The objectives of the current study were to assess the feasibility of using stayability traits to improve fertility of Nellore cows and to examine the genetic relationship among the stayabilities at different ages. Stayability was defined as whether a cow calved every year up to the age of 5 (Stay5), 6 (Stay6), or 7 (Stay7) yr of age or more, given that she was provided the opportunity to breed. Data were analyzed based on a maximum a posteriori probit threshold model to predict breeding values on the liability scale, whereas the Gibbs sampler was used to estimate variance components. The EBV were obtained using all animals included in the pedigree or bulls with at least 10 daughters with stayability observations, and average genetic trends were obtained in the liability and transformed to the probability scale. Additional analyses were performed to study the genetic relationship among stayability traits, which were compared by contrasting results in terms of EBV and the average genetic superiority as a function of the selected proportion of sires. Heritability estimates and SD were 0.25 +/- 0.02, 0.22 +/- 0.03, and 0.28 +/- 0.03 for Stay5, Stay6, and Stay7, respectively. Average genetic trends, by year, were 0.51 +/- 0.34, and 0.38% for Stay5, Stay6, and Stay7, respectively. Estimates of EBV SD, in the probability scale, for all animals included in the pedigree and for bulls with at least 10 daughters with stayability observations were 7.98 and 12.95, 6.93 and 11.38, and 8.24 and 14.30% for Stay5, Stay6, and Stay7, respectively. A reduction in the average genetic superiorities in Stay7 would be expected if the selection were based on Stay5 or Stay6. Nonetheless, the reduction in EPD, depending on selection intensity, is on average 0.74 and 1.55%, respectively. Regressions of the sires' EBV for Stay5 and Stay6 on the sires' EBV for Stay7 confirmed these results. The heritability and genetic trend estimates for all stayability traits indicate that it is possible to improve fertility with selection based on a threshold analysis of stayability. The SD of EBV for stayability traits show that there is adequate genetic variability among animals to justify inclusion of stayability as a selection criterion. The potential linear relationship among stayability traits indicates that selection for improved female traits would be more effective by having predictions on the Stay5 trait.

Effect of mechanical loading on the I-c degradation behavior of Bi-2223 tapes

During the winding process of HTS coils the tapes of Bi-2223 are subjected to the influence of bending strain, axial strain, compressive force and torsional deformation resulting in I-c degradation. In the literature the effects of the individual strain components are separately analyzed in spite of during coil winding and energizing the strain-stress effects are combined. In this work using commercial tapes of Bi-2223 Ag/AgMg with and without stainless steel reinforcement several samples were wound on cylindrical FRP G-10 holder in which different combined strains are applied. Measurements of I - V characteristic curves are done to determine the degree of critical current degradation and the operational limits. The results are compared with the I, values of short samples and other specimens subjected to deformation generated by loading types such as tensile and bending strain.

Molecular epidemiology of virulent Rhodococcus equi from foals in Brazil: virulence plasmids of 85-kb type I, 87-kb type I, and a new variant, 87-kb type III

We investigated the prevalence of virulent Rhodococcus equi in clinical isolates from 41 foals (19 sporadic and seven endemic cases) in Brazil between 1991 and 2003. of the 41 virulent isolates, six contained an 85-kb type I plasmid, 33 contained an 87-kb type I plasmid, both of which have been found in isolates from the Americas, and the remaining two contained a new variant, which did not display the EcoRI, EcoT221 and BamHI digestion patterns of the 11 representative plasmids already reported (85-kb types I-IV; 87-kb types I and II; 90-kb types I-V). We tentatively designated the new variant as the '87-kb type III' plasmid, because its BamHI digestion pattern is similar to that of the 87-kb type I plasmid. This is the first report of the molecular epidemiology surveillance of virulent R. equi in clinical isolates from Brazilian foals. (C) 2004 Elsevier Ltd. All rights reserved.

Effect of atmosphere on the electrical properties of TiO2-SnO2 varistor systems

This work illustrates the advancement of research on TiO2-based electroceramics. In this work will be presented that the addition of different dopants, as well as thermal treatments at oxidizing and inert atmosphere, influences of the densification, the mean grain size and the electrical properties of the TiO2-based varistor ceramics. Dopants like Ta2O5, Nb2O5, and Cr2O3 have an especial role in the barrier formation at the grain boundary in the TiO2 varistors, increasing the nonlinear coefficient and decreasing the breakdown electric field. The influence of Cr'(Ti) is to increase the O' and O'(2) adsorption at the grain boundary interface and to promote a decrease in the conductivity by donating electrons to O-2 adsorbed at the grain boundary. In this paper, TiO2 and (Sn,Ti)O-2-based studies of polycrystalline ceramics, which show a non-linear I-V electrical response typical of low voltage varistor systems are also presented. All these systems are potentially promising for varistor applications. (C) 2004 Kluwer Academic Publishers.

Measurement of the t-channel single-top-quark production cross section and of the |V (tb)| CKM matrix element in pp collisions at root s=8 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for pair production of third-generation scalar leptoquarks and top squarks in proton-proton collisions at v root s=8 TeV

A search for pair production of third-generation scalar leptoquarks and supersymmetric top quark partners, top squarks, in final states involving tau leptons and bottom quarks is presented. The search uses events from a data sample of proton-proton collisions corresponding to an integrated luminosity of 19.7 fb(-1), collected with the CMS detector at the LHC with root s = 8 TeV. The number of observed events is found to be in agreement with the expected standard model background. Third-generation scalar leptoquarks with masses below 740 GeV are excluded at 95% confidence level, assuming a 100% branching fraction for the leptoquark decay to a tau lepton and a bottom quark. In addition, this mass limit applies directly to top squarks decaying via an R-parity violating coupling. lambda(') (333). The search also considers a similar signature from top squarks undergoing a chargino-mediated decay involving the Rparity violating coupling. lambda(')(3jk). Each top squark decays to a tau lepton, a bottom quark, and two light quarks. Top squarks in this model with masses below 580 GeV are excluded at 95% confidence level. The constraint on the leptoquark mass is the most stringent to date, and this is the first search for top squarks decaying via. lambda(')(3jk). (C) 2014 The Authors. Published by Elsevier B. V.

Contribution of electrical parameters on the dynamical behaviour of a nonlinear electromagnetic damper

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

Determination of the highest no-effect dose (HNED) and of the elimination pattern for cocaine in horses

Cocaine is one of the most widespread illegal stimulants utilized by the human population throughout the world. The aim of this study was to establish the highest no-effect dose (HNED) of cocaine on the spontaneous locomotor activity (SLA) of horses in a behavior chamber, and thereby to determine the maximal acceptable threshold of the urinary drug concentration in horses. Twelve English thoroughbred mares received 0.02, 0.03, 0.04, 0.08 or 0.12 mg kg(-1) cocaine i.v. or saline solution (control). It was noted that doses above 0.04 mg kg(-1) induced a significant increase in SLA (P < 0.05, Tukey's test). No significant increase in SLA was seen in the mares that received 0.03 mg kg(-1), but the animals showed important behavioral changes that did not occur after the 0.02 mg kg(-1) dose. It was concluded that the HNED of cocaine for horses in a behavior chamber is 0.02 mg kg(-1). After injection of this dose in five horses, urine samples were collected at predetermined intervals through vesical catheterization. The concentrations of cocaine, norcocaine, benzoylecgonine and ecgonine methyl ester were quantified by liquid chromatography/electrospray ionization tandem mass spectrometry. Cocaine and norcocaine concentrations remained consistently below the level of detection. Benzoylecgonine reached a mean (+/- SEM) maximum concentration of 531.9 +/- 168.7 ng ml(-1) after 4 h, whereas ecgonine methyl ester peaked 2 h after injection at a concentration of 97.2 +/- 26.5 ng ml(-1). The maximum admissible concentration for cocaine and/or metabolites in the urine of horses is difficult to establish unequivocally because of the substantial individual variation in the drug elimination pattern observed in horses, which can be inferred by the large standard error of the means obtained. Copyright (C) 2002 John Wiley Sons, Ltd.

Avaliação da função renal de cães sob dois protocolos para administração da cisplatina

OBJETIVO: Avaliar a função renal de cães sadios, sob dois protocolos para administração de cisplatina. MÉTODOS: Todos os animais foram submetidos a três sessões de quimioterapia com cisplatina (60mg/m², iv) a intervalos de 21 dias. Foi realizada fluidoterapia com solução de cloreto de sódio a 0,9%, (25mL/kg/hora,iv), durante duas horas e, após administração de cisplatina, por mais uma hora. Os animais do grupo 2 receberam furosemida (2mg/kg, iv) 20 minutos antes da administração da cisplatina. A avaliação da função renal foi feita por exame clinico, urinálise, concentrações séricas de uréia e creatinina, clearance de creatinina, excreção fracionada de sódio e de potássio e razão proteína: creatinina urinária. As avaliações foram feitas imediatamente antes e 1, 2, 5, e 21 dias após cada uma das três sessões de quimioterapia. RESULTADOS: Mantiveram-se dentro da normalidade, não sendo detectados sinais de lesões ou insuficiência renal. Os animais que não receberam furosemida sofreram aumento gradativo nas concentrações séricas de creatinina e diminuição no clearance da mesma. CONCLUSÃO: O regime de fluidoterapia empregado mostra ser efetivo em minimizar a ação nefrotóxica da cisplatina e benefício adicional importante é obtido pela administração de furosemida.