Direct determination of Cu, Cd, Ni and Pb in aquatic humic substances by graphite furnace atomic absorption spectrometry

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

Use of direct and iterative solvers for estimation of SNP effects in genome-wide selection

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Direct observation of oxidative stress on the cell wall of Saccharomyces cerevisiae strains with atomic force microscopy

We imaged pores on the surface of the cell wall of three different industrial strains of Saccharomyces cerevisiae using atomic force microscopy. The pores could be enlarged using 10 mM diamide, an SH residue oxidant that attacks surface proteins. We found that two strains showed signs of oxidative damage via changes in density and diameter of the surface pores. We found that the German strain was resistant to diamide induced oxidative damage, even when the concentration of the oxidant was increased to 50 mM. The normal pore size found on the cell walls of American strains had diameters of about 200nm. Under conditions of oxidative stress the diameters changed to 400nm.This method may prove to be a useful rapid screening process (45-60 min) to determine which strains are oxidative resistant, as well as being able to screen for groups of yeast that are sensitive to oxidative stress. This rapid screening tool may have direct applications in molecular biology (transference of the genes to inside of living cells) and biotechnology (biotransformations reactions to produce chiral synthons in organic chemistry.

Stability analysis of power systems described with detailed models by automatic method

The power system stability analysis is approached taking into explicit account the dynamic performance of generators internal voltages and control devices. The proposed method is not a direct method in the usual sense since conclusion for stability or instability is not exclusively based on energy function considerations but it is automatic since the conclusion is achieved without an analyst intervention. The stability test accounts for the nonconservative nature of the system with control devices such as the automatic voltage regulator (AVR) and automatic generation control (AGC) in contrast with the well-known direct methods. An energy function is derived for the system with machines forth-order model, AVR and AGC and it is used to start the analysis procedure and to point out criticalities. The conclusive analysis itself is made by means of a method based on the definition of a region surrounding the equilibrium point where the system net torque is equilibrium restorative. This region is named positive synchronization region (PSR). Since the definition of the PSR boundaries have no dependence on modelling approximation, the PSR test conduces to reliable results. (C) 2008 Elsevier Ltd. All rights reserved.

Dynamic stationary response of reinforced plates by the boundary element method

A direct version of the boundary element method (BEM) is developed to model the stationary dynamic response of reinforced plate structures, such as reinforced panels in buildings, automobiles, and airplanes. The dynamic stationary fundamental solutions of thin plates and plane stress state are used to transform the governing partial differential equations into boundary integral equations (BIEs). Two sets of uncoupled BIEs are formulated, respectively, for the in-plane state ( membrane) and for the out-of-plane state ( bending). These uncoupled systems are joined to formamacro-element, in which membrane and bending effects are present. The association of these macro-elements is able to simulate thin-walled structures, including reinforced plate structures. In the present formulation, the BIE is discretized by continuous and/or discontinuous linear elements. Four displacement integral equations are written for every boundary node. Modal data, that is, natural frequencies and the corresponding mode shapes of reinforced plates, are obtained from information contained in the frequency response functions (FRFs). A specific example is presented to illustrate the versatility of the proposed methodology. Different configurations of the reinforcements are used to simulate simply supported and clamped boundary conditions for the plate structures. The procedure is validated by comparison with results determined by the finite element method (FEM).

Direct Detection of Mycobacterium bovis in Bovine Lymph Nodes by PCR

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Alternative genotyping method for the single nucleotide polymorphism A2959G (AF159246) of the bovine CAST gene

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

A novel in situ Polymerase chain reaction hybridisation assay for the direct detection of bovine herpesvirus type 5 in formalin-fixed, paraffin-embedded tissues

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

Direct detection of infectious bursal disease virus from clinical samples by in situ reverse transcriptase-linked polymerase chain reaction

The presence of the very virulent (vv) Brazilian strain of infectious bursal disease virus (IBDV) was determined in the bursa of Fabricius, thymus and liver of 2-week-old broilers from a flock with a higher than expected mortality. For this purpose, a direct in situ reverse transcriptase (RT)-linked polymerase chain reaction (PCR) method was developed using specific primers for vvIBDV. Unlabelled forward and reverse biotinylated oligonucleotides were used for RT-PCR in a one-step method and the respective products were revealed by a direct enzymatic reaction. The results were compared with those obtained by standard RT-PCR using general primers for IBDV and virus isolation. The virus isolation, RT-PCR and in situ RT-PCR revealed positive results on the bursa of Fabricius in 86%, 80% and 100%, respectively. The in situ RT-PCR detected vvIBDV in all tested thymus and liver samples, whereas the standard RT-PCR detected virus in 80% and 90% of the samples, respectively. After three consecutive passages on chicken embryonated eggs, IBDV was isolated from 64% of the thymus samples and 30% of the liver samples. In the present study, no classical or antigenic variants of IBDV were detected. The developed in situ RT-PCR assay was able to detect the very virulent strain of IBDV with a higher sensitivity than the conventional RT-PCR and virus isolation.

Direct and transdentinal antibacterial activity of chlorhexidine

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A simple method for estimating global DNA methylation using bisulfite PCR of repetitive DNA elements

We report a method for studying global DNA methylation based on using bisulfite treatment of DNA and simultaneous PCR of multiple DNA repetitive elements, such as Alu elements and long interspersed nucleotide elements (LINE). The PCR product, which represents a pool of approximately 15000 genomic loci, could be used for direct sequencing, selective restriction digestion or pyrosequencing, in order to quantitate DNA methylation. By restriction digestion or pyrosequencing, the assay was reproducible with a standard deviation of only 2% between assays. Using this method we found that almost two-thirds of the CpG methylation sites in Alu elements are mutated, but of the remaining methylation target sites, 87% were methylated. Due to the heavy methylation of repetitive elements, this assay was especially useful in detecting decreases in DNA methylation, and this assay was validated by examining cell lines treated with the methylation inhibitor 5-aza-2'deoxycytidine (DAC), where we found a 1-16% decrease in Alu element and 18-60% LINE methylation within 3 days of treatment. This method can be used as a surrogate marker of genome-wide methylation changes. In addition, it is less labor intensive and requires less DNA than previous methods of assessing global DNA methylation.

Direct limits on the B-s(0) oscillation frequency

We report results of a study of the B-s(0) oscillation frequency using a large sample of B-s(0) semileptonic decays corresponding to approximately 1 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider in 2002-2006. The amplitude method gives a lower limit on the B-s(0) oscillation frequency at 14.8 ps(-1) at the 95% C.L. At Delta m(s)=19 ps(-1), the amplitude deviates from the hypothesis A=0 (1) by 2.5 (1.6) standard deviations, corresponding to a two-sided C.L. of 1% (10%). A likelihood scan over the oscillation frequency, Delta m(s), gives a most probable value of 19 ps(-1) and a range of 17

Direct Measurement of the W Boson Width

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Direct measurement of the mass difference between top and antitop quarks

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of particle size on the properties of Pt-Ru/C catalysts prepared by a microemulsion method

Pt-Ru/C nanocatalysts were prepared by a microemulsion method using different values of water/surfactant molar ratio in order to get different particle sizes. Crystallite sizes and structural properties were determined by X-ray diffraction. Particle size and distribution were characterized by transmission electron microscopy and average composition was determined by energy-dispersive X-ray analysis. Thermogravimetric analysis was used to estimate the amount of supported metals. Differential scanning calorimetry measurements indicated the presence of hydrous ruthenium oxides in the as-prepared catalysts. Results for the oxidation of adsorbed CO as well as for methanol oxidation revealed significant differences in the behavior of the prepared catalysts. All together, the results demonstrate that the variation of particle size produces changes in other properties of the Pt-Ru/C catalysts and that to establish direct correlations between electrocatalytic activity and particle size is not possible because the effects of the different parameters cannot be separated. (c) 2007 the Electrochemical Society.