The wavelet method as an alternative for reducing ionospheric effects from single-frequency GPS receivers

The ionospheric effect is one of the major errors in GPS data processing over long baselines. As a dispersive medium, it is possible to compute its influence on the GPS signal with the ionosphere-free linear combination of L1 and L2 observables, requiring dual-frequency receivers. In the case of single-frequency receivers, ionospheric effects are either neglected or reduced by using a model. In this paper, an alternative for single-frequency users is proposed. It involves multiresolution analysis (MRA) using a wavelet analysis of the double-difference observations to remove the short- and medium-scale ionosphere variations and disturbances, as well as some minor tropospheric effects. Experiments were carried out over three baseline lengths from 50 to 450 km, and the results provided by the proposed method were better than those from dual-frequency receivers. The horizontal root mean square was of about 0.28 m (1 sigma).

Determination of snake-necked turtle Hydromedusa tectifera (Cope, 1870) (Testudines: Chelidae) plasma protein concentrations by refractometry and the biuret method.

The purpose of this study was to evaluate the accuracy of hand-held refractometer in determining plasma protein concentrations in South American snake-necked turtle (Hydromedusa tectifera) as compared with the standard biuret method. The results indicated that plasma protein values may be accurately determined in snake- necked turtle with a hand-held refractometer.

Influences of the insertion method in glass ionomer cement porosity

The aim of this study was to evaluate the presence of porosities inside the glass ionomer cement (GIC) after different techniques of material insertion. MATERIAL and METHOD: Specimens were prepared with high-viscosity GIC Ketac Molar Easymix and divided into three groups according to the insertion method: spatula (PI), Centrix injector (CI), and low-cost syringe (LCS). The specimens were fractured and observed with scanning electronic microscopy to quantitatively evaluate porosity inside the material using Image J Software. RESULTS: Statistical analysis, ANOVA application, and Tukey test to significance level of 5%, revealed that there was no statistical difference between the groups. CONCLUSION: Although the use of LCS has not decreased the porosity of the material, this insertion method is easy, accessible, and low cost, which makes it a viable alternative of use in the ART technique and in others bucal health programs. Microsc. Res. Tech., 2012. (c) 2012 Wiley Periodicals, Inc.

Measurement of the top quark mass in the lepton plus jets channel using the ideogram method

A measurement of the top quark mass using events with one charged lepton, missing transverse energy, and jets in the final state, collected by the D0 detector from p (p) over bar collisions at root s=1.96 TeV at the Fermilab Tevatron collider, is presented. A constrained fit is used to fully reconstruct the kinematics of the events. For every event a top quark mass likelihood is calculated taking into account all possible jet assignments and the probability that an event is signal or background. Lifetime-based identification of b jets is employed to enhance the separation between t (t) over bar signal and background from other physics processes and to improve the assignment of the observed jets to the quarks in the t (1) over bar hypothesis. We extract a multiplicative jet energy scale (JES) factor in situ, greatly reducing the systematic effect related to the jet energy measurement. In a data sample with an integrated luminosity of 425 pb(-1), we observe 230 candidate events, with an estimated background of 123 events, and measure m(t)=173.7 +/- 4.4(stat+JES)(-2.0)(+2.1)(syst) GeV. This result represents the first application of the ideogram technique to the measurement of the top quark mass in lepton+jets events.

Evaluation of the photoelectrocatalytic method for oxidizing chloride and simultaneous removal of microcystin toxins in surface waters

The production of chlorine was investigated in the photoelectrocatalytic oxidation of a chloride-containing solution using a TiO(2) thin-film electrode biased at current density from 5 to 50 mA cm(-2) and illuminated by UV light. Such parameters as chloride concentrations from 0.001 to 0.10 mol L(-1), pH 2-12, and interfering salts were varied in this study in order to determine their effect on this oxidation process. At an optimum condition this photoelectrocatalytic method can produce active chlorine at levels compatible to water disinfections processes using a chloride concentration higher than 0.010 mol L(-1) at a pH of 4 and a current density of 30 mA cm(-2). The method was successfully applied to treat surface water collected from a Brazilian river. After 150 min of photoelectrocatalytic oxidation, we obtained a 90% reduction in total organic carbon removal, a 100% removal of turbidity, a 93% decrease in colour and a chemical oxygen demand (COD) removal of around 96% (N=3). The proposed technology based on photoelectrocatalytic oxidation was also tested in treating 250 mL of a solution containing 0.05 mol L(-1) NaCl and 50 mu g L(-1) of Microcystin aeruginosa. The bacteria is completely removed after 5 min of photoelectrocatalysis following an initial rate constant removal of -0.260 min(-1), suggesting that the present method could be considered as a promising alternative to chlorine-based disinfections. (C) 2008 Elsevier Ltd. All rights reserved.

Structural and optical properties of GdAlO3:RE3+ (RE = Eu or Tb) prepared by the Pechini method for application as X-ray phosphors

In this work, GdAlO3:RE3+ (RE = Eu or Tb) was successfully prepared by the Pechini method at lower temperatures when compared to others methods as solid-state synthesis and sol-gel process. In accordance to the XRD data, the fully crystalline single-phase GdAlO3 could be obtained at 900 degrees C. The differential thermal analysis (DTA) shows a crystallization peak at 850 degrees C. The samples are composed by monocrystalline particles (50-120 nm) exhibiting the formation of aggregates among them, which indicates the beginning of the sinterization process. This feature indicates a strong tendency to the formation of aggregates, which is a suitable ability for the close-packing of particles, and hence a potential application in X-ray intensifying screens. Luminescence measurements indicate Gd3+ -> RE3+ energy transfer. The Eu3+ emission spectra exhibit all the characteristics D-5(0) -> F-7(j) transitions and the observed profile suggests that RE3+ ions occupy at least one site without center of symmetry. For terbium-doped samples, the D-5(3) -> F-7(j) (blue emission) and D-5(4) -> F-7(j) (green emission) transitions were observed and the ratio between them may depend on the Tb3+ content due to cross-relaxation processes. (C) 2009 Elsevier B.V. All rights reserved.

Correlation between the spectroscopic and structural properties with the occupation of Eu3+ sites in powdered Eu3+-doped LiTaO3 prepared by the Pechini method

In this work we studied the structural and optical properties of lithium tantalate (LiTaO3) powders doped with Eu3+ ions. We have examined the different sites occupied by the rare earth ion through the correlation of the DRX data analyzed with the Rietveld method and some spectroscopic parameters derived from the Eu3+ luminescence. Adirect relation was established between the lattice parameters and the occupation fraction of Eu3+ in each LiTaO3 site. The occupation fraction was set as the relative population of Eu3+ ions for each site obtained by means of the intensity, baricenter, and the spontaneous emission coefficients of the D-5(0)-> F-7(0) transitions. We concluded that the unit cell parameter a presents the same behavior of the Eu3+ occupation fraction in Ta5+ sites as a function of the Eu3+ content in LiTaO3. The same was observed for the variation in Eu3+ occupation fraction in the Li+ site and the unit cell parameter c with the Eu3+ content. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3204967]

Synthesis and characterization of PLZT (9/65/35) by the Pechini method and partial oxalate

ZrTiO4 (ZT), obtained by the Pechini method, was used as precursor for obtaining PLZT (lead lanthanum zirconium titanate). An aqueous solution of oxalic acid was prepared with particles of ZT, Pb(NO3)(2) and La2O3. After the PbC2O4 and La2O3 precipitate on ZT particles, the materials were calcined and X-ray diffraction (XRD) showed the cubic phase of PLZT. This material was sintered, in two steps, and a density of about 8.0 g/cm(3) was obtained. After the second sintering the XRD pattern showed the occurrence of tetragonal and rhombohedral phases. This was caused by a stoichiometric deviation and the material showed a high optical transparency. (C) 1998 Elsevier B.V. B.V. All rights reserved.

Influence of the concentration of Sb2O3 and the viscosity of the precursor solution on the electrical and optical properties of SnO2 thin films produced by the Pechini method

SnO2:Sb multi-layer coatings were prepared by the Pechini method. An investigation was made of the influence of the concentration of Sb2O3 and the viscosity of the precursor solution on the electrical and optical properties of SnO2 thin films. The use of a multi-layer system as an alternative form of increasing the packing and. thus. decreasing porosity proved to be efficient, decreasing the system's resistivity without altering its optical properties. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Quantitative structural analysis of the transition from LT-LixCoO2 to HT-LixCoO2 using the rietveld method: correlation between structure and electrochemical performance

A quantitative phase analysis was made of LiXCoO2 powders obtained by two distinct chemical methodologies at different temperatures (from 400 to 700degreesC). A phase analysis was made using Rietveld refinements based on X-ray diffraction data, considering the LiXCoO2 powders as a multiphase system that simultaneously contained two main phases with distinct, layered and spinel-type structures. The sults showed the coexistence of both structures in LiXCoO2 obtained at low temperature (400 and 500degreesC), although only the layered structure was detected at higher temperatures (600 and 700degreesC, regardless of the chemical powder process employed. The electrochemical performance, evaluated mainly by the cycling reversibility of LiXCoO2 in the form of cathode insertion electrodes, revealed that there is a close correlation between structural features and the electrochemical response, with one of the redox processes (3.3 v/3.9 v) associated only with the presence of the spinel-type structure. (C) 2003 Elsevier B.V. All rights reserved.

Determination of soybean seed respiration rate by the titulation method

This trial was carried out under laboratory conditions, with three lots of Iguacu soybean seeds, to determine the respiration rate by the titulation method. A randomized complete block design was used, with four repetitions, each one of them with 50 seeds and a control without seeds for each lot. The seeds were placed in gerbox with 40 mi of KOH 0.1N, on distilled water wet blotting paper for fixing the CO2 produced by seeds respiration. The material was placed in germinator at constant 25 degrees C for 16, 24 and 48 hours. After these periods, the titulation of the fixative solution was performed with HCl 0.1N to check the respiration rate. The most deteriorated seeds were those that presented the highest respiration rates, which were measured in mg of CO2/g of dry matter, when compared with the most vigorous lots. The titulation method was suitable for the evaluation of soybean seed respiration rate because the final results separated the lots in three different quality levels that were compatible with the results obtained from the accelerated aging and emergence.

Effect of PbO excess on the formation of lead magnesium niobate perovskite by the columbite method

The effect of lead excess on the pyrochlore-type formation in Pb(Mg1/3Nb2/3)O-3 (PMN) powders has been investigated. The polymeric precursor method was used in the synthesis of the columbite in association to the partial oxalate method to synthesize the PMN powder samples. Structure refinement of the columbite precursor and PMN powders was carried out using the Rietveld method. The quantitative phase analysis showed that the amount of perovskite phase is not affected by PbO excess, but a great excess drives the pyrochlore-type formation so that 3 wt.% of PbO causes the predominance of Mg-containing pyrochlore phase. Using the refined data obtained from the Rietveld refinement, the compositional fluctuation in the perovskite phase was calculated from Nb/Mg ratio values and Pb occupation factor. Mg inclusion occurs concomitant with Ph one into PMN perovskite phase and this effect is directed by PbO excess during powder synthesis. (C) 2003 Elsevier B.V. All rights reserved.

Clinical evaluation of abutment teeth of removable partial denture by means of the Periotest method

Prosthodontics should be one of the means of establishing conditions for the maintenance of periodontal health. The forces applied to the abutment teeth and their effects are very important considerations in the design and construction of the removable partial dentures. This 6-month follow-up clinical study evaluated the degree of mobility of abutment teeth of distal extension and tooth supported removable partial dentures by using Periotest. Two types of clasp design were selected for evaluation. In cases with unilateral and bilateral distal-extension, a clasp design including a T clasp of Roach retentive arm, a rigid reciprocal arm and a mesial rest were used. For the abutments of tooth-supported removable partial dentures, a second clasp design with a cast circumferential buccal retentive arm, a rigid reciprocal clasp arm and a rest adjacent to the edentulous ridges was selected. A total of 68 abutment teeth was analysed. Periotest values were made at the time of denture placement (control) and at 1, 3 and 6 months after the denture placement. The statistical analysis was performed using Friedman test. All analysis was performed at a 0.05 level of significance. The results revelled that no significant changes in tooth mobility were observed during the 6-months follow-up (P > 0.05). In conclusion, our findings suggest that adequate oral hygiene instructions, careful prosthetic treatment planning and regular recall appointments play an important role in preventing changes in abutment tooth mobility caused by removable partial denture placement.

Seeding of PMN powders made by the Pechini method

The partial oxalate method, with the columbite route, associated with the Pechini method, was used to obtain a very fine ceramic powder at low temperature. Using this route it was possible to obtain a very reactive powder and to synthesize a lead magnesium niobate (PMN) powder with up to 100% of perovskite phase at a lower temperatures than the PbO melting point. The influence of the BaTiO3 and PbTiO3 seeds in the phase formation, along with time and temperature during the PMN calcination, was also investigated. The amount of 2% of BaTiO3 seeds promoted PMN powder formation with 100% of perovskite phase and a very narrow particle size distribution. (C) 2001 Elsevier B.V. Ltd and Techna S.r.l. All rights reserved.