The influence of the thickness on the functional properties of cassava starch edible films

The properties of edible films are influenced by several factors, including thickness. The purpose of this paper was to study the influence of thickness on the viscoelasticity properties, water vapor permeability, color and opacity of cassava starch edible films. These films were prepared by a casting technique, the film-forming solutions were 1, 2, 3 and 4% (w/v) of starch, heated to 70degreesC. Different thicknesses were obtained by putting 15 to 70 g of each solution on plexiglass plates. After drying at 30degreesC and ambient relative humidity, these samples were placed for 6 days at RH of 75%, at 22degreesC. The sample thicknesses were determined by a digital micrometer (+/-0.001 mm), as the average of nine different points. The viscoelasticity properties were determined by stress relaxation tests with a texture analyser TA.XT2i (SMS), being applied the Burgers model of four parameters. The water vapor permeability was determined with a gravimetric method, and color and opacity were determined using a Miniscan XE colorimeter, operated according to the Hunterlab method. All the tests were carried out in duplicate at 22degreesC. Practically, the four visco-elasticity properties calculated by the Burgers model had the same behavior, increasing with the thickness of all films, according to a power law model. The water vapor permeability and the color difference increased linearly with the thickness (0.013-0.144 mm) of all films prepared with solution of 1 to 4% of starch. on the other hand, the effect of the variation of the thickness over the opacity, was more important in the films with 1 and 2% of starch. It can be concluded that the control of the thickness in the elaboration of starch films by the casting technique is of extreme importance.

Texture and Microstructure of Gelatin/Corn Starch-Based Gummy Confections

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.

Possible origin of RHIC Rout/Rsid HBT results

The effects of opacity of the nuclei together with a blackbody type of emission along the system history are considered as a means to explain the ratio Rout/Rsid observed by STAR and PHENIX collaborations at RHIC. Within our model, no flow is required to explain the data trend of this ratio for large surface emissivities. © 2003 Elsevier Science B.V. All rights reserved.

Prevalence of trachoma in a population of the upper Rio Negro basin and risk factors for active disease

Purpose: To determine the prevalence of trachoma in Sao Gabriel da Cachoeira (SGC), the only urban community of the upper Rio Negro Basin of the Amazon state in Brazil, near the Colombian border, and to investigate the risk factors associated with the active forms of the disease. Methods: A total of 1702 people (440 children up to 9 years and 1069 adults aged 15 years and above) were examined. The sample was selected from a probabilistic household sampling procedure based on census data and a previous study of trachoma prevalence in Sao Gabriel da Cachoeira. A two-stage probabilistic household cluster sample was drawn. Household units were randomly selected within each cluster. A variety of socioeconomic and hygiene variables were studied in order to determine the risk factors for active trachoma in a household. Results: The total prevalence of trachoma was 8.9%. Prevalence of active trachoma (TF and/or TI) in children aged 1-9 years was 11.1% and trachomatous trichiasis in adults aged 15 years and above was 0.19%. Trachomatous scarring reached a peak of 22.4% for subjects between 50 to 60 years of age. Corneal opacity occurred in subjects aged 50 years and older with a prevalence of 2.0%. No sex effect was found on the overall prevalence of trachoma in SGC. Risk factors associated with active trachoma were mainly related to poor socioeconomic indicators. Conclusions: Despite the ubiquitous presence of water, the analysis of the risk factors associated with the active forms of the disease supports the idea that a low personal standard of hygiene and not water availability per se, is the key factor associated with trachoma. Copyright © 2008 Informa Healthcare USA, Inc.

Influência da fotopolimerização e da cor da resina composta na microdureza

Objective: To study the influence of color opacity and light-curing systems (halogen light vs blue LED) on the microhardness of a composite resin. Methods: Esthet-X composite resin (Dentsply), shades A2 and A2-O, was inserted in a stainless steel matrix (5 mm diameter and 2 mm deep) and was light cured for 40 seconds with a halogen light source (XL 3000; 3M/ESPE) or a blue LED (Optilight LD II; Gnatus). Eight groups of 15 specimens each were formed, and were further divided according to the light-curing systems, the exposed area (base and surface), and the opacity of the composite resin, producing 120 specimens. The specimens were next stored in distilled water for 24 hours, embedded in a chemically activated acrylic resin, then subjected to finishing and polishing with sandpaper and felt discs. Microhardness was measured with a Vickers Digital Microhardness meter, with a 50 g load for 30 seconds. The obtained microhardness means were analyzed by ANOVA and Tukey's multiple-comparison test at 5% significance level. Results: The surface microhardness was always greater than the base microhardness, regardless of the light-curing source. The halogen light lamp produced significantly higher composite resin microhardness means than the blue LED (57.61 vs. 42.53 HV) (p<0.05). Statistically significant differences (p<0.05) were obtained between the microhardness means for the different composite opacities; lowest microhardness in depth was produced by the A2-O shade. Conclusion: Composite resin opacity as well as the light-curing system influenced the microhardness of the material.

Anterior restorations in bleached teeth: Difficulty establishing the color after bleaching

It is becoming more common for patients to look for cosmetic procedures in dental offices. The search for lost or desired esthetics by patients is increasingly frequent and the professional must be able to meet this demand. To do this, dentists not only need to return the tooth back to its normal functioning state but also promote esthetic excellence. In this context, the association of cosmetic procedures, such as teeth whitening and restorative procedures, such as direct adhesive restorations is very common. The composite resins employed nowadays allow the reproduction of various optical properties of natural teeth. With these composite resins, it is possible to reproduce features such as translucency, opacity and specific features of the dental element, to bring back the esthetic harmony of the smile. This article reports a clinical case demonstrating the placement, in a stratified manner, of composite resins in bleached teeth, as well as the reproduction of optical and natural aspects of the teeth. In order to achieve esthetic and functional success of the restored procedure, it is important to be familiar with the new techniques and new materials in the marketand above all, we must know when and where to use them.

Effect of ceramic shade on the degree of conversion of a dual-cure resin cement analyzed by FTIR

Objectives: The aim of this research was to evaluate the degree of monomer conversion of different resin cement shades when photocured under different feldspathic ceramic shades. The photocuring time was also evaluated as well as the translucency of each ceramic shade. Methods: Three VITA VM7 ceramic shades (Base Dentin 0M1, Base Dentin 2M2 and Base Dentin 5M3) were used to determine the translucency percentage. A spectrophotometer MiniScan was used to measure the opacity percentage of each specimen (2-mm-thick) and then the translucency was calculated. To measure the degree of conversion (DC), the resin cement (Variolink II; A3 Yellow and transparent) specimens (thickness: 100 μm) were photocured under a ceramic block (2-mm-thick) for 20 or 40 s. Specimens photocured without the ceramic block were used as control. Sixteen groups (n = 3) were evaluated. Micro-ATR/FTIR spectrometry was used to evaluate the extent of polymerization of all specimens after 24 h. The %DC was calculated of experimentally polymerized versus maximally polymerized composite. Results: The translucency percentages of 0M1, 2M2 and 5M3 ceramics were 12.41 (1.02)%, 5.75 (1.91)% and 1.07 (0.03)%, respectively. The %DC of both resin cement shades cured under ceramic 5M3 was significantly lower than the other groups (p < 0.05). The %DC of 0M1 groups exhibited no significant difference from 2M2 groups (p > 0.05), with the exception of the transparent cement photocured for 40 s. Conclusion: Photocuring under 2 mm ceramic showed that the increase in chroma saturation significantly decreased Variolink II resin cement %DC (100-μm-thick). © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Aspectos clínicos do enxerto conjuntival 360° e do implante da membrana amniótica criopreservada no tratamento de úlceras de córnea em cães

To evaluate the clinical application of implant of the canine cryopreserved amniotic membrane (DMEM plus DMSO 1:1) and 360° conjunctival flap in the treatment of progressive corneal ulceration. 10 dogs of the different breeds, males and females, aging four months to four years old with deep corneal ulceration and different clinical progression were divided in two groups: G1=360° conjunctival graft (n=5) and G2=implant of amniotic membrane, sutured at the edge of the ulcer with epithelial side facing up, associated with the third eyelid flap (n=5). The comparative analysis between groups was: complications, blepharospasm, ocular secretion, corneal vascularization, epithelial defect and corneal opacification in six moments (first emergency care, surgery and 3, 7, 15 and 30 days of postoperative). Without epithelial defect was evaluated quality of the scar. It was used score scale for subjective to qualify of the ocular signs. In G1, it was observed the non-adherence of the conjunctival graft to the ulcer (n=2), dehiscence of the suture (n=2), anterior synechia (n=2) and intense chemosis (n=1). In G2, it was not observed these complications. It was not significant difference between the groups to others ocular parameters, but it was different among the start and end moments of the same groups (ocular secretion, corneal vascularization, epithelial defect). The corneal opacity was more intense in G1. According to the clinical results, the cryopreserved amniotic membrane implant proved to be as effective in the corneal ulceration in comparison to the 360° conjunctival flap, because probably, the membrane promoted a trophic support for epithelialization, anti-inflamatory effect associated with important to the end result phenotype.

Use of platelet-rich plasma in the treatment of deep corneal ulcers induced in rabbits.clinical and histomorphometric evaluation

The repair process induced corneal ulcer in rabbits using platelet-rich plasma in the form of eyedrop or clot was clinically evaluated and compared. Sixty rabbits were divided into four groups of 15 animals, denominated platelet group (PG), clot group (CLG), control group (CG), and amniotic control group (AG). Experimental groups were then subdivided into three groups (M4, M7, M30), corresponding to the end of the evaluation period. There were no differences between treatments regarding ocular sensitivity, chemosis and ocular secretion. The groups treated with PRP either as eyedrop or a clot showed less opacity than the animals treated only with amniotic membrane at the moment of the final evaluation. The presence of corneal ulcers in the groups treated with PRP showed lower intensity than the other groups. Histomorphometric examination showed that corneal epithelization in the initial phase of the lesion was greater when using PRP. The use of amniotic membrane promoted corneal epithelial and stromal thickness, as well as synergism when associated to PRP.

Influence of ethanol and glycerol concentration over functional and structural properties of zein-oleic acid films

This study was performed in order to determine the effect of the addition of different concentrations of glycerol and ethanol over functional and structural properties of zein-oleic acid films. Films were prepared from zein and oleic acid formulations, containing: 0, 10, 20 and 30% (w/w) of glycerol as plasticizer and 75, 80, 85, 90 and 95% (v/v) of ethanol as zein solvent. Water vapor permeability (WVP) at 4 and 24 C, opacity, water solubility and structural behavior of the film were assessed. The film water barrier properties, WVP and water solubility, were increased when higher ethanol concentration and lower glycerol concentration were used. Furthermore, WVP at 4 C was lower than WVP at 24 C due to the crystalline solid state of oleic acid at lower temperatures. Likewise, opacity, homogeneity and structure of the composite film were improved as ethanol increased and glycerol lowered. © 2013 Elsevier B.V. All rights reserved.

Biodesel de mamona em trator: desempenho em função do período de armazenamento e da proporção biodiesel/diesel em condição de preparo de solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desempenho operacional e opacidade da fumaça do trator agrícola em função do tipo de biodiesel (soja x murumuru) em operação de preparo do solo

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Efeito de biodeisel de mamona no diesel interior e metropolitano em trator agrícola

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biodiesel de mamona em trator agrícola na operação de preparo do solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)