The relationship of oral malodor in patients with or without periodontal disease

Background: Halitosis has been correlated with the concentration of volatile sulfur compounds (VSC) produced in the oral cavity by metabolic activity of bacteria colonizing the periodontal area and the dorsum of the tongue. The aim of this study was to determine whether there is some relationship between the presence of N-benzoyl-DL-arginine-2-napthylamide (BANA)positive species Treponema denticola, Porphyromonas gingivalis, and Bacteroides forsythus and clinical and oral malodor parameters.Methods: Twenty-one subjects (21 to 59 years old) with probing depths (PD) >3.0 mm and 20 subjects (21 to 63 years old) with PD less than or equal to3.0 mm (controls) participated. The quality of the mouth air was assessed organoleptically, and a portable sulfide monitor was used to measure the concentration of VSC. Clinical parameters, plaque index (PI) and gingival index (GI), were obtained from 6 teeth. Samples for BANA test were taken from the dorsal surface of the tongue, saliva, and the 6 reference teeth.Results: the scores of PI, GI, subgingival samples that tested positive for BANA hydrolyzing species, organoleptic ratings, and VSC values were significantly higher in the subjects with PD >3.0 mm (P <0.01, Mann-Whitney U test). There was a correlation between BANA hydrolysis by subgingival plaque bacteria and VSC values (r = 0.55, P <0.01), and between GI and VSC values (r = 0.48, P <0.05) in patients with PD >3.0 mm. There was no significant correlation between these parameters in the control group.Conclusion: These results confirm that the BANA hydrolyzing bacteria in the subgingival plaque are an important source of malodor production in the oral cavity.

Adsorptive potentiometric stripping analysis of trace tamoxifen at a glassy carbon electrode

A highly sensitive adsorptive stripping procedure for trace measurement of the anticancer drug tamoxifen is described. The method is based on controlled adsorptive accumulation of the drug at an electrochemically treated glassy carbon electrode, followed by chronopotentiometric measurement of the surface species. The chronopotentiometric operation effectively addresses the large background contribution inherent to the glassy carbon electrode to yield a detection limit of 4 x 10(-10) M after 4 min preconcentration. The adsorptive stripping response is evaluated with respect to electrode type and conditioning, accumulation potential and lime, stripping current, pH, drug concentration, potential interferences, and other variables. Applicability to urine samples is illustrated. (C) 1997 Elsevier B.V. B.V.

Study of the effects of exposure to ionizing irradiation on the materials used for dental restoration

A quantitative study was made about the effects caused by ionizing irradiation on materials used for dental restoration (amalgams, compound resins and compomere), aiming to alleviate in bearers of head and neck cancer, the possible harmful effects of radiotherapy perceived when the repaired teething is within the radiation field. Research also encourages further studies for new alternative materials to be used in dental repair of patients submitted to radiotherapy for head and neck cancer. Test samples were submitted to a gamma radiation beam coming from a cobalt-therapy source and analyzed according to the X-ray fluorescence technique, comparing the chemical composition of the samples before and after irradiation. Radiation detectors such as an ionization chamber and a Geiger-Muller were used to measure the rate of residual dose. Gamma spectrometry with Nal detectors was also performed on the same samples. Results showed that there was no significant change in the chemical composition and that at post-irradiation, samples did not exhibit radiation emission, that is to say they had not become radioactive.

Determination of acetaldehyde in fuel ethanol by high-performance liquid chromatography with electrochemical detection

The cyclic voltammetric behavior of acetaldehyde and the derivatized product with 2,4-dinitrophenylhydrazine (DNPHi) has been studied at a glassy carbon electrode. This study was used to optimize the best experimental conditions for its determination by high-performance liquid chromatographic (HPLC) separation coupled with electrochemical detection. The acetaldehyde-2,4-dinitrophenyl.hydrazone (ADNPH) was eluted and separated by a reversed-phase column, C-18, under isocratic conditions with the mobile phase containing a binary mixture of methanol/LiCl(aq) at a concentration of 1.0 x 10(-3) M (80:20 v/v) and a flow rate of 1.0 mL min(-1). The optimum condition for the electrochemical detection of ADNPH was +1.0 V vs. Ag/AgCl as a reference electrode. The proposed method was simple, rapid (analysis time 7 min) and sensitive (detection limit 3.80 mu g L-1) at a signal-to-noise ratio of 3:1. It was also highly selective and reproducible [standard deviation 8.2% +/- 0.36 (n = 5)]. The analytical curve of ADNPH was linear over the range of 3-300 mg L-1 per injection (20 mu L), and the analytical recovery was > 99%.

NUMERICAL DETERMINATION OF THE ORDER OF PHASE-TRANSITIONS IN ISING SYSTEMS WITH MULTISPIN INTERACTIONS

The method of the fourth-order cumulant of Challa, Landau, and Binder is used together with the Monte Carlo histogram technique of Ferrenberg and Swendsen to study the order of the phase transitions of two-dimensional Ising systems with multispin interactions in the horizontal direction and two-body interactions in the vertical direction.

Development and Evaluation of a Nanoporous Iron (Hydr)oxide Electrode for Phosphate Sensing

Nanoporous iron (hydr) oxide electrodes are evaluated as phosphate sensors using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The intensity of the reduction peak current (I-cp) of the ferrihydrite working electrode is tied to phosphate concentration at low pH; however, a hematite electrode combined with the use of EIS provided reliable sensing data at multiple pH values. Nanoporous hematite working electrodes produced an impedance phase component (theta) that shifts with increasing phosphate, and, at chosen frequencies, theta values were fitted for the range 1 nM to 0.1 mM phosphate at pH 4 and pH 7 in 5 mM NaClO4.

Photothermal Study of Two Different Nanofluids Containing SiO2 and TiO2 Semiconductor Nanoparticles

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A device to improve the Schleger and Turner method for sweating rate measurements

The objective of this study was to test a device developed to improve the functionality, accuracy and precision of the original technique for sweating rate measurements proposed by Schleger and Turner [Schleger AV, Turner HG (1965) Aust J Agric Res 16:92-106]. A device was built for this purpose and tested against the original Schleger and Turner technique. Testing was performed by measuring sweating rates in an experiment involving six Mertolenga heifers subjected to four different thermal levels in a climatic chamber. The device exhibited no functional problems and the results obtained with its use were more consistent than with the Schleger and Turner technique. There was no difference in the reproducibility of the two techniques (same accuracy), but measurements performed with the new device had lower repeatability, corresponding to lower variability and, consequently, to higher precision. When utilizing this device, there is no need for physical contact between the operator and the animal to maintain the filter paper discs in position. This has important advantages: the animals stay quieter, and several animals can be evaluated simultaneously. This is a major advantage because it allows more measurements to be taken in a given period of time, increasing the precision of the observations and diminishing the error associated with temporal hiatus (e.g., the solar angle during field studies). The new device has higher functional versatility when taking measurements in large-scale studies (many animals) under field conditions. The results obtained in this study suggest that the technique using the device presented here could represent an advantageous alternative to the original technique described by Schleger and Turner.

Synthesis and Photoluminescence Behavior of the Eu3+ Ions as a Nanocoating over a Silica Stober Matrix

In this work, a SiO2 spherical were prepared by the Stober Method and then recovered with a single layer of Eu2O3 oxide (SiO2@Eu2O3) obtained by the Polymeric Precursor Method. The SiO2@Eu2O3 powder was heated treated at 100, 300, 400, 500 and 800 A degrees C. The samples were characterized by the Scanning Electonic Microscopy (SEM), Thermal Analysis (TGA/DTA), and the luminescent properties of the SiO2@Eu2O3 powders were studied by their emission and excitation spectra as well as by the lifetime measurements of the Eu3+ D-5(0) -> aEuro parts per thousand F-7(2) transition. The SEM analysis shows that the silica prepared by the Stober Method is spherical with a particle size of 460 nm. The emission spectra of the SiO2@Eu2O3 powders presented the Eu3+ characteristics bands related to the D-5(0) -> aEuro parts per thousand F-7(J) (J = 0, 1, 2, 3, 4) transitions at 577, 591, 616, 649 and 695 nm, respectively. The band related to the D-5(0) -> aEuro parts per thousand F-7(2) transition is the most intense in the spectra, and its intensity decreases with the temperature enhancement. The decay curves of the SiO2@Eu2O3 samples presented monoexponential features, and the obtained lifetime values were higher than the Eu2O3 oxide. It was possible to conclude that the D-5(0) -> aEuro parts per thousand F-7(2) hypersensitive transition is strongly dependent on the Eu3+ surrounding.

Electrooxidation and determination of dopamine using a Nafion (R)-cobalt hexacyanoferrate film modified electrode

The electrocatalysis of dopamine has been studied using a cobalt hexacyanoferrate film (CoHCFe)-modified glassy carbon electrode. Using a rotating disk CoHCFe-modified electrode, the reaction rate constant for dopamine was found to be 3.5 x 105 cm(3) mol(-1) s(-1) at a concentration of 5.0 x 10(-5) mol L-1. When a Nafion (R) film is applied to the CoHCFe-modified electrode surface a high selectivity for the determination of dopamine over ascorbic acid was obtained. The analytical curve for dopamine presented linear dependence over the concentration range from 1.2 x 10(-5) to 5.0 x 10(-4) mol L-1 with a slope of 23.5 mA mol(-1) L and a linear correlation coefficient of 0.999. The detection limit of this method was 8.9 x 10(-6) mol L-1 and the relative standard deviation for five measurements of 2.5 x 10(-4) mol L-1 dopamine was 0.58%.

Hydrogenated amorphous carbon as protective coating for a forming tool

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

Influence of polymerization on the synthesis of SrTiO3: Part II. Particle and agglomerate morphologies

Morphologies of SrTiO3 particles and agglomerates synthesized by the traditional Pechini route and by the polymer precipitation route were characterized by the nitrogen adsorption/desorption technique and by transmission electron microscopy (TEM). A cluster structure of nanometric particles forming large agglomerates which are broken during pressing followed by cluster rearrangement was observed. The mean particle size is larger for SrTiO3 obtained by the Pechini route and is related to the precursor thermal decomposition and particle growth during calcination. The particle growth is controlled by neck growth among particles and further motion of the particle boundary. © 1995.

SAXS measurements of the porosity in Cu(II)-doped SnO2 xerogels during crystallization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of viscoelastic characteristics of the colloidal suspensions on the formation of SnO2 supported membranes

SnO2 supported membranes have been prepared by sol-casting on alumina tubular substrate, using aqueous colloidal suspensions prepared by sol-gel route. The viscoelastic behaviour during sol ageing was analyzed by dinamic rheologial measurements. The complex viscosity and the storage and loss moduli have been followed during the sol-gel transition and the results have been correlated with the linear aggregates growth and the scalar percolation models. The scanning electron microscopy has evidenced that the homogeneity and thickness of the membrane depend on the sol ageing time. Crack-free and homogeneous membranes have been obtained for coated layers of 0.5μm thickness. © 1997 Trans Tech Publications.

Properties of BaBi2Ta2O9 thin films prepared by chemical solution deposition technique for dynamic random-access memory applications

We report on the properties of BaBi2Ta2O9 (BBT) thin films for dynamic random-access memory (DRAM) and integrated capacitor applications. Crystalline BBT thin films were successfully fabricated by the chemical solution deposition technique on Pt-coated Si substrates at a low annealing temperature of 650°C. The films were characterized in terms of structural, dielectric, and insulating properties. The electrical measurements were conducted on Pt/BBT/Pt capacitors. The typical measured small signal dielectric constant and dissipation factor, at 100 kHz, were 282 and 0.023, respectively, for films annealed at 700°C for 60 min. The leakage current density of the films was lower than 10-9 A/cm2 at an applied electric field of 300 kV/cm. A large storage density of 38.4 fC/μm2 was obtained at an applied electric field of 200 kV/cm. The high dielectric constant, low dielectric loss and low leakage current density suggest the suitability of BBT thin films as dielectric layer for DRAM and integrated capacitor applications.