Disulfide Biochemistry in 2-Cys Peroxiredoxin: Requirement of Glu50 and Arg146 for the Reduction of Yeast Tsa1 by Thioredoxin

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

Molecular tools and analytical approaches for the characterization of farm animal genetic diversity

Genetic studies of livestock populations focus on questions of domestication, within- and among-breed diversity, breed history and adaptive variation. In this review, we describe the use of different molecular markers and methods for data analysis used to address these questions. There is a clear trend towards the use of single nucleotide polymorphisms and whole-genome sequence information, the application of Bayesian or Approximate Bayesian analysis and the use of adaptive next to neutral diversity to support decisions on conservation.

Review of Fluconazole Properties and Analytical Methods for Its Determination

Fluconazole, -(2.4-diflurofenil)--(1H-triazol-1-methyl)-1H-1,2,4-triazol-1-ethanol, is an antifungal of triazoles class. It shows activity against species of Candida sp., and it is indicated in cases of oropharyngeal candidiasis, esophageal, vaginal, and deep infection. Fluconazole is a selective inhibitor of ergosterol, a steroid exclusive of the cell membrane of fungal cells. Fluconazole is highly absorbed by the gastrointestinal tract, and it spreads easily by body fluids. The main adverse reactions related to the use of fluconazole are nausea, vomiting, headache, rash, abdominal pain, diarrhea, and alopecia in patients undergoing prolonged treatment with a dose of 400 mg/day. In the form of raw material, pharmaceutical formulations, or biological material, fluconazole can be determined by methods such as titration, spectrophotometry, and thin-layer, gas, and liquid chromatography. This article discusses the pharmacological and physical-chemical properties of fluconazole and also the methods of analysis applied to the determination of the drug.

Analytical optimization of spread and change of exponential decay of generalized Wannier functions in one dimension

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Triplet carbonyls: from photophysics to biochemistry

Triplet carbonyls can be generated not only from the thermal cleavage of dioxetanes, but also enzymatically from appropriate substrates. The excited species can phosphoresce with an intensity depending upon the extent of shielding from deactivating oxygen collisions, react and also transfer energy, thus promoting sensitized emission and sensitized photochemistry. © 1994.

Analytical chemistry in a liquid film/droplet

The measurement of nitrogen dioxide at the parts-perbillion level is described. The experimental arrangement consists of two optical fibers placed on opposite sides of and in contact with a liquid film (14-57 μL in volume) supported on a U-shaped wire guide and two tubular conduits (one of which constitutes the means for the delivery of the liquid), light from a green (555 nm) light-emitting diode enters the liquid film, composed of Griess-Saltzman reagent. The transmitted light is measured by a referenced photodetection arrangement. Sample gas flows past the droplet at a low flow rate (typically 0.10-0.25 L/min). The response is proportional to the sampling period and the analyte concentration. The limit of detection for this nonoptimized arrangement is estimated to be <10 ppb by volume for a 5 min sample. Some unusual characteristics are observed. The initial absorbance, when most of the analyte/reaction product is still near the surface, is higher than that when the content of the droplet is fully mixed. The signal depends on the sample flow rate in a nonmonotonic fashion, first increasing and then decreasing with increasing sampling rate; the specific chemistry involved in the collection and determination of NO2 may be responsible.

Analytical expressions for the FM and AM responses of an integrated laser-modulator

The need for low-chirp and compact transmitters for high-bit-rate optical links has led to the development of integrated laser electroabsorption modulators (ILM). We have investigated feedback effects inducing frequency chirp by developing a model treating the ILM as a whole and obtained analytical expressions of the FM and AM responses. The variation of the frequency chirp with the residual facet reflectivity of the modulator section is calculated. The model predicts the unusual peak in the measured frequency responses and has been used to define design rules.

Power analysis applying the instantaneous complex power analytical expressions on a RL symmetrical three-phase system

This paper enhances some concepts of the Instantaneous Complex Power Theory by analyzing the analytical expressions for voltages, currents and powers developed on a symmetrical RL three-phase system, during the transient caused by a sinusoidal voltage excitation. The powers delivered to an ideal inductor will be interpreted, allowing a deep insight in the power phenomenon by analyzing the voltages in each element of the circuit. The results can be applied to the understanding of non-linear systems subject to sinusoidal voltage excitation and distorted currents.

Thermal behaviour and analytical study of the production of TiSnOx from the mixed 8-hydroxyquinolinates

Solubility and pH precipitation studies were carried out to obtain the binuclear complex {[TiO(C9H6NO)2][Sn(C9H6NO) 2]} involving 8-hydroxyquinoline as chelating agent. The compound, the individual mononuclear complexes and their physical mixture were evaluated by means of techniques such as TG, DTA, elemental analysis, X-ray diffraction, IR spectroscopy. The properties of the original compounds and also the thermoanalytical conditions exerted a great influence on the degree of crystallinity and on the crystalline phase of the mixed oxide obtained as final product of the thermal decomposition.

Analytical functions for the calculation of hyperspherical potential curves of atomic systems

We present angular basis functions for the Schrödinger equation of two-electron systems in hyperspherical coordinates. By using the hyperspherical adiabatic approach, the wave functions of two-electron systems are expanded in analytical functions, which generalizes the Jacobi polynomials. We show that these functions, obtained by selecting the diagonal terms of the angular equation, allow efficient diagonalization of the Hamiltonian for all values of the hyperspherical radius. The method is applied to the determination of the 1S e energy levels of the Li + and we show that the precision can be improved in a systematic and controllable way. ©2000 The American Physical Society.

One-dimensional analytical model for oxide thin film growth on Ti metal layers during laser heating in air

This paper presents the theoretical and experimental results for oxide thin film growth on titanium films previously deposited over glass substrate. Ti films of thickness 0.1 μm were heated by Nd:YAG laser pulses in air. The oxide tracks were created by moving the samples with a constant speed of 2 mm/s, under the laser action. The micro-topographic analysis of the tracks was performed by a microprofiler. The results taken along a straight line perpendicular to the track axis revealed a Gaussian profile that closely matches the laser's spatial mode profile, indicating the effectiveness of the surface temperature gradient on the film's growth process. The sample's micro-Raman spectra showed two strong bands at 447 and 612 cm -1 associated with the TiO 2 structure. This is a strong indication that thermo-oxidation reactions took place at the Ti film surface that reached an estimated temperature of 1160 K just due to the action of the first pulse. The results obtained from the numerical integration of the analytical equation which describes the oxidation rate (Wagner equation) are in agreement with the experimental data for film thickness in the high laser intensity region. This shows the partial accuracy of the one-dimensional model adopted for describing the film growth rate. © 2001 Elsevier Science B.V.

An analytical solution to the optimal power flow

This letter presents an approach for a geometrical solution of an optimal power flow (OPF) problem for a two-bus system (slack and PV busses). The algebraic equations for the calculation of the Lagrange multipliers and for the minimum losses value are obtained. These equations are used to validate the results obtained using an OPF program.

Electrochemical sensors: A powerful tool in analytical chemistry

Potentiometric, amperometric and conductometric electrochemical sensors have found a number of interesting applications in the areas of environmental, industrial, and clinical analyses. This review presents a general overview of the three main types of electrochemical sensors, describing fundamental aspects, developments and their contribution to the area of analytical chemistry, relating relevant aspects of the development of electrochemical sensors in Brazil.

HPLC-EICD: An Useful Tool for the Pursuit of Novel Analytical Strategies for the Detection of Antioxidant Secondary Metabolites

Living cells are continuously exposed to a variety of challenges that exert oxidative stress and are directly related with senescence and the onset of various pathological conditions such as coronary heart disease, rheumatoid arthritis and cancer. Nevertheless, living organisms have developed a complex antioxidant network to counteract reactive species that are detrimental to life. With the aim of bio-prospecting plant species from the Brazilian Cerrado and Atlantic Forest, we have established a methodology to detect secondary antioxidant metabolites in crude extracts and fractions obtained from plant species. Combining HPLC with an electrochemical detector allowed us to detect micromolecules that showed antioxidant activities in Chimarrhis turbinata (DC) leaf extracts. Comparison with purified flavonoid standards led us to identify the compounds in their natural matrices giving valuable information on their antioxidant capacity.