Gelation and drying of weakly bonded silica-PPO nanocomposites

Silica-poly(oxypropylene) (PPO) nanocomposites containing PPO with weak physical bonds between the organic (PPO) and inorganic (silica) phases were obtained by the sol-gel procedure. Three precursor sols containing silica and PPO with molecular weights of 1000, 2000 and 4000g/mol were prepared. The structure changes during the whole sol-gel process, i.e. sol formation, sol-gel transition and gel aging and drying were investigated in situ by small angle X-ray scattering (SAXS). The experimental SAXS curves corresponding to sols and wet gels containing PPO of molecular weight 1000g/mol indicate that the aggregates formed during the studied process are fractal objects. Close to the sol-gel transition and during gel aging the fractal dimension is D=2.5. A clearly different structure evolution occurs in samples prepared with PPO with molecular weights 2000 and 4000 g/mol. Our SAXS results indicate the presence of two coexisting and well-defined structure levels, one of them corresponding to small silica clusters and the other to large silica aggregates. These two levels remain along the whole transformation. The SAXS curves of all dry samples are similar to those of the corresponding wet gels suggesting that no significant changes at nanoscopic scale occur during the drying process.

Application of compression test in analysis of mechanical and color changes in grapefruit juice powder as related to glass transition and water activity

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Enamel Defects in Maxillary Central Incisors of Infants With Unilateral Cleft Lip

Objective: To evaluate the presence of enamel alterations in deciduous maxillary central incisors of infants with unilateral cleft lip and alveolar ridge, with or without cleft palate, and to compare the occurrence and location of these alterations between the central incisor adjacent to the cleft and the contralateral incisor.Design: Intraoral clinical examination was performed after tooth cleaning and drying by a single examiner with the aid of a dental mirror, dental probe, and artificial light, with the child positioned on a dental chair. The defects were recorded in a standardized manner according to the criteria of the Modified Developmental Defects of Enamel Index.Setting: Hospital for Rehabilitation of Craniofacial Anomalies (HRAC) at Bauru, São Paulo, Brazil.Patients: One hundred one infants were evaluated. All were white, of both genders, aged 12 to 36 months and had at least two thirds of the crowns of maxillary incisors erupted.Results: Demarcated opacity was the most common defect at both cleft and noncleft sides, followed by diffuse opacity. The occurrence of hypoplasia at the cleft side was 11.8%. Most defects affected less than one third of the crown.Conclusion: The occurrence of enamel defects in deciduous maxillary central incisors of patients with unilateral cleft lip was 42.6%, mainly affecting the cleft side as to both number and severity.

The effectiveness of educational practice in diabetic foot: a view from Brazil

Background: The aim of the present study was to evaluate the prevention and self-inspection behavior of diabetic subjects with foot at ulcer risk, no previous episode, who participated in the routine visits and standardized education provided by the service and who received prescribed footwear. This evaluation was carried out using a questionnaire scoring from 0-10 (high scores reflect worse practice compliance).Results: 60 patients were studied (30 of each sex); mean age was 62 years, mean duration of the disease was 17 years. As for compliance, 90% showed a total score <= 5, only 8.7% regularly wore the footwear supplied; self foot inspection 65%, 28,3% with additional familiar inspection; creaming 77%; proper washing and drying 88%; proper cutting of toe nails 83%; no cuticle cutting 83%; routine shoe inspection 77%; no use of pumice stones or similar abrasive 70%; no barefoot walking 95%.Conclusion: the planned and multidisciplinary educational approach enabled high compliance of the ulcer prevention care needed in diabetic patients at risk for complications. In contrast, compliance observed for the use of footwear provided was extremely low, demonstrating that the issue of its acceptability should be further and carefully addressed. In countries of such vast dimensions as Brazil multidisciplinary educational approaches can and should be performed by the services providing care for patients with foot at risk for complications according to the reality of local scenarios. Furthermore, every educational program should assess the learning, results obtained and efficacy in the target population by use of an adequate evaluation system.

Changes in sensitivity of the isolated guinea-pig vas deferens induced by a lyophilized Phoradendron latifolium leaf infusion

The effect of a lyophilized mistletoe infusion (LMI) was studied on isolated guinea-pig vas deferens. LMI caused a contraction which was partially blocked by phentolamine but not by atropine. LMI caused a shift to the left of the norepinephrine concentration-effect curve (CEC), an effect which appeared to be blocked by atropine and was absent in animals previously treated with reserpine and α-methyl-para-tyrosine. The increase of the norepinephrine maximal response induced by LMI was not blocked by atropine or pharmacological denervation. LMI caused a shift to the right of the acetylcholine CEC and had no effect on the acetylcholine maximal response. These results suggest that the effects seem to be due mainly to the presence of potassium ion in the LMI; however, the participation of muscarinic agonist(s) of reduced intrinsic activity or some tyramine-like substance could not be ruled out.

EXAFS and XRD analyses of the structural evolutions involved during drying of SnO2 hydrogels

In order to determine structural changes during drying of inorganic gels, the local and long-range order structure of SnO2-x(OH)2x xerogels resulting from drying hydrogels with different concentrations of electrolyte (Cl- and NH+ 4) have been measured by extended X-ray absorption fine structure (EXAFS), X-ray diffraction (XRD) and N2 adsorption techniques. EXAFS measurements performed at the Sn K edge on the hydrogels and xerogels show the existence of microcrystallites with the cassiterite structure. Two drying modes have been used: freeze drying and drying by evaporation at 45°C. It is shown that the microcrystallite size determined by XRD and EXAFS techniques on the drying mode and on the electrolyte concentrations. The microcrystallite size measured on the freeze dried xerogels is similar to that of their parent hydrogels, whatever the concentration of electrolyte; however, during drying by evaporation, a preferential growth of microcrystallites along the c-axis of the cassiterite structure is observed. The size of these crystallites is enhanced with a decrease of the electrolyte concentration. Specific surface areas calculated by the Brunauer-Emmett-Teller method indicate that this preferential growth is related to the improvement of the network connectivity. The comparison of both drying processes indicates that crystallization and polycondensation are independent phenomena. © 1995 Elsevier Science B.V. All rights reserved.

Fungus incidence on peanut grains as affected by drying method and Ca nutrition

An experiment was conducted to study the effects of liming and drying method on Ca nutrition, fungus infection and aflatoxin production potential on peanut (Arachis hypogea) grains. Peanut cv. Botutatu was grown in the absence or presence of liming to raise the base saturation of the soil from 20 to 56%. Calcium contents of the soil were increased from 5.5 to 14.6 mmol((c))kg-1 and pH from 4.2 to 4.9. After harvest, plants and pods were dried in (1) shade, (2) field down to 100 g water kg-1 (3) field down to 250 g water kg-1 and transferred to a forced-air oven at 30°C, (4) field down to 360 g water kg-1 and transferred to a forced-air oven at 30°C. Calcium contents were analyzed in the grains, pericarps and seed coats. The incidence of Aspergillus spp., Penicillium spp., Rhizopus spp. and potential aflatoxin production in vitro were evaluated, as well as the seed coat thickness. The seed coat was thicker when peanut was grown in the presence of lime, leading to a decrease in seed infection by Aspergillus spp. and Penicillium spp. When plants were dried in shade, the growth of aflatoxinogenic fungi was independent of liming. However, in plants dried in the field or field + oven, the development of these fungi was decreased and even suppressed when the Ca content of the seed coat was increased from 2.2 to 5.5 g kg-1.

Residues of Some Pesticides in Fresh and Dried Apricots

The persistence of three pesticides (fenitrothion, dimethoate, and ziram) in apricots in field conditions and their fate during the drying process were studied. After the treatments, the pesticides showed fast decay rates with pseudo-first-order kinetics and half-lives ranging from 6.9 to 9.9 days. The drying process showed a different effect on residue concentrations in dried apricots: omethoate (metabolite of dimethoate) and ziram residues had almost doubled, while fenitrothion disappeared and dimethoate remained constant.

Bacillus thuringiensis development from 1971 to 1996: Cases of a research group in Brazil

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

Seasonal variation in coumarin content of Mikania glomerata

Mikania glomerata Spengal extract contains approximately 0.5 percent of coumarin, a substance that displays anti-inflammatory and expectoratory activities. Extracts from different young leaves of plants collected during the early evening of December and July contained the highest levels coumarin. Plants dried in oven with circulating air contained 7.3 mg of coumarin/g of dry weight, demonstrating that this was the most appropriate drying condition for Mikania glomerata.

Small-angle x-ray scattering study of the structural evolution of the drying of sonogels with the liquid phase exchanged by acetone

The structural evolution on the drying of wet sonogels of silica with the liquid phase exchanged by acetone, obtained from tetraethoxisilane sonohydrolysis, was studied in situ by small-angle x-ray scattering (SAXS). The periods associated to the structural evolution as determined by SAXS are in agreement with those classical ones established on basis of the features of the evaporation rate of the liquid phase in the obtaining of xerogels. The wet gel can be described as formed by primary particles (microclusters), with characteristic length a ∼ 0.67 nm and surface which is fractal, linking together to form mass fractal structures with mass fractal dimension D=2.24 in a length scale ξ∼6.7 nm. As the network collapses while the liquid/vapor meniscus is kept out of the gel volume, the mass fractal structure becomes more compacted by increasing D and decreasing ξ, with smoothing of the fractal surface of the microclusters. The time evolution of the density of the wet gels was evaluated exclusively from the SAXS parameters ξ, D, and a. The final dried acetone-exchanged gel presents Porod's inhomogeneity length of about 2.8 nm and apparently exhibits an interesting singularity D →3, as determined by the mass fractal modeling used to fit the SAXS intensity data for the obtaining of the parameters ξ and D.

Determination of vanadium in urine by electrothermal atomic absorption spectrometry using hot injection and preconcentration into the graphite tube

In this work it was developed a procedure for the determination of vanadium in urine samples by electrothermal atomic absorption spectrometry using successive injections for preconcentration into a preheated graphite tube. Three 60 μL volumes were sequentially injected into the atomizer preheated to a temperature of 110°C. Drying and pyrolysis steps were carried out after each injection. A chemical modifier, barium difluoride (100 mg L-1), and a surfactant, Triton X-100 (0.3% v v-1), were added to the urine sample. When injecting into a hot graphite tube, the sample flow-rate was 0.5 μL s-1. The limits of detection and quantification were 0.54 and 1.82 without preconcentration, and 0.11 and 0.37 μg L-1 with preconcentration, respectively. The accuracy of the procedure was evaluated by an addition-recovery experiment employing urine samples. Recoveries varied from 96.0 to 103% for additions ranging from 0.8 to 3.5 μg L-1 V. The developed procedure allows the determination of vanadium in urine without any sample pretreatment and with minimal dilution of the sample.

Cinedacryocystography in the diagnosis of lacrimal obstruction in children

Purpose: To analyze the cinedacryocystography in children with congenital nasolacrimal obstruction suspicion. Methods: The cinedacryocystographic examination was done in 143 children (58% of girls and 42% of boys) younger than 5 years old, suspected of congenital nasolacrimal obstruction. The exams were done under general anesthesia and the children were probed immediately when obstruction was detected. Results: Epiphora, discharge or both were the most common complaints. Nevertheless 11% children had undergone unsuccessfully probing once, no one had any radiologic evaluation previously. The cinedacryocystographic exam showed nasolacrimal duct obstruction in 65,73%. Permeable lacrimal vies were presented in 34,3% of the children with epiphora. The obstruction was mainly at the Arlt's sinus. Using the cinedacryocystography, it was possible to observe the lacrimal sac enlargement and alterations in the contiguous structures such as hypertrophic turbinates (91,1%), sinusitis (44,6%) and septum deviation (24,1%). Conclusion: Cinedacryocystographic evaluation provides important information about lacrimal system obstruction in children, therefore, it is useful in all children with suspected congenital lacrimal obstruction.

Effect of rotary instrumentation and of the association of calcium hydroxide and chlorhexidine on the antisepsis of the root canal system in dogs

This study aimed at evaluating the antisepsis of the root canal system (RCS) and periapical region (PR) provided by rotary instrumentation associated with chlorhexidine + calcium hydroxide as intracanal medicament. Chronic periapical lesions were induced in 26 pre-molar roots in two dogs. After microbiological sampling, automatic instrumentation using the Profile system and irrigation with 5.25% sodium hypochlorite solution, with a final rinse of 14.3% EDTA followed by profuse irrigation with physiological saline were carried out in 18 root canals. After drying the canals, a paste based on calcium hydroxide associated with a 2% chlorhexidine digluconate solution was placed inside them. After 21 days, the medication was removed, leaving the root canals empty and coronally sealed. After 96 hours, a final microbiological sample was obtained, followed by histomicrobiological processing by the Brown & Brenn method. Eight untreated root canals represented the control group (C-G). Based on the Mann-Whitney test at a confidence level of 5% (p < 0.05), the procedures of antisepsis used offered significant efficacy (p < 0.05) resulting in 100.0% of the canals free of microorganisms. In the C-G, an elevated incidence of various microbial morphotypes was confirmed in all sites of the RCS, with the presence of microbial colonies in the periapical region. In contrast, the experimental group showed a similar pattern of infection in the RCS, although less intense and a reduced level of periapical infection (p < 0.05). It was concluded that adequate instrumentation followed by the application of calcium hydroxide + chlorhexidine offered significant elimination of microorganisms.

Fluoridation of the public water supply and prevalence of dental fluorosis in a peripheral district of the municipality of Bauru, SP

Objectives: The objectives of this study were to assess the fluoride concentration in the public water supply and the prevalence of dental fluorosis in schoolchildren between 7 and 15 years old, living in a peripheral district of the municipality of Bauru. Material and Methods: For this, fifty two water samples were collected on three different days of one week. These samples were analyzed for fluoride by means of the ion-sensitive electrode method (Orion 9609) coupled to a potentiometer (Procyon, model 720). In this method, 1.0 mL of TISAB II (Orion) was added to 1.0 mL of the sample. For the epidemiological survey of fluorosis, 52 schoolchildren of both genders, aged between 7 and 15 were assessed, with prior authorization from their caretakers. Only one person examined the children, after supervised toothbrushing and drying with cotton wool rolls. The TF index was used. Results: The fluoride concentrations in the water samples ranged from 0.62 to 1.20 mg/L, with a mean of 0.9 mg/L. The prevalence of dental fluorosis was 33%, with severity ranging from TF1 to TF4 (Kappa of 0.73 and concordance of 83.33%). Conclusions: The results from the analysis of water samples indicated a fluoride concentration greater than recommended for Bauru. The fluorosis levels found were higher than expected for a peripheral district, in which water is one of the few sources of fluoride.