Glass-to-Vitroceramic Transition in the Yttrium Aluminoborate System: Structural Studies by Solid-State NMR

The crystallization of laser glasses in the system (B(2)O(3))(0.6){(Al(2)O(3))(0.4-y)(Y(2)O(3))(y)} (0.1 <= y <= 0.25) doped with different levels of ytterbium oxide has been investigated by X-ray powder diffraction, differential thermal analysis, and various solid-state NMR techniques. The homogeneous glasses undergo major phase segregation processes resulting in crystalline YBO(3), crystalline YAI(3)(BO(3))(4), and residual glassy B(2)O(3) as the major products. This process can be analyzed in a quantitative fashion by solid-state (11)B, (27)Al, and (89)Y NMR spectroscopies as well as (11)B{(27)Al} rotational echo double resonance (REDOR) experiments. The Yb dopants end up in both of the crystalline components, producing increased line widths of the corresponding (11)B, (27)Al, and (89)Y NMR resonances that depend linearly on the Yb/Y substitution ratio. A preliminary analysis of the composition dependence suggests that the Yb(3+) dopant is not perfectly equipartitioned between both crystalline phases, suggesting a moderate preference of Yb to substitute in the crystalline YBO(3) component.

Chemical modification of a nanocrystalline TiO(2) film for efficient electric connection of glucose oxidase

A novel biosensor for glucose was prepared by adsorption of 1,1`-bis(4-carboxybenzyl)-4,4`-bipyridinium di-bromide compound (H(2)BpybcBr(2)) onto the surface of a nanocrystalline TiO(2) film deposited onto FTO glasses, which was used as a platform to assemble the enzyme glucose oxidase to the electrode surface. The H(2)BpybcBr(2)/TiO(2)/FTO modified electrode was characterized by scanning electron microscopy, X-ray fluorescence image, cyclic voltammograms and spectroelectrochemical measurements. The immobilization of GOD on functionalized TiO(2) film led to stable amperometric biosensing for glucose with a linear range from 153 mu mol L(-1) to 1.30 mmol L(-1) and a detection limit of 51 mu mol L(-1). The apparent Michaelis-Menten constant (K(m)) was estimated to be 3.76 mmol L(-1), which suggested a high enzyme-substrate affinity. The maximum electrode sensitivity was 1.25 mu A mmol L(-1). The study proved that the combination of viologen mediators with TiO(2) film retains the electrocatalytic activity of the enzyme, and also enhances the electron transfer process, and hence regenerating the enzyme in the reaction with glucose. (C) 2010 Elsevier Inc. All rights reserved.

Ny förpackning för Renat Brännvin åt Vin & Sprit AB

The purpose of this degree project is to come up with a new package to Renat Brännvin for »Vin & SpritAB« and make the product more attractive on the market of bars, restaurants and hotels. The commissionhas included to decide the material of the package, whether it´s possible to manufacture the productand to make an estimation of the costs.The conditions that »Vin & Sprit AB« set up was to make the product attractive to a younger targetgroup, in this case people from 20 to 40 years old. As Renat Brännvin is considered to be a product of firstclass it´s of great importance that the package reflects the look of a premium product.At first we looked at the history of the company »Vin & Sprit AB« and Renat Brännvin. We decidedthat the package schould consist of a bottle, glasses and a device used when serving the liquor. To getinspiration before sketching we studied different kinds of bottles, glasses and serving devices. We madea lot of different sketches to start with after which we consult with Ingrid Florén – our supervisor from»Vin & Sprit AB« – agreed on one. That one we developed and we made more accurate sketches in 3DStudioMAX.At last we looked at the opportunities to produce the bottle by questioning different manufacturers. Wewanted to know the limitations to consider when making a bottle.

Estudo de sistemas vítreos para infiltração em alumina

The system in-Ceram Alumina, produced by VITA, consists in a technique of prepare of a substructure of ceramics to dental crowns. First burning is made in the alumina decanted by slip casting process under a stone die that reproduces the tooth prepared to receive a crown. In a second burning, alumina is infiltrated by vitreous system, giving to this set a high mechanic resistance. In this work, it s made a study of the composition of a new infiltrating material more used nowadays, giving to alumina desirable mechanics proprieties to its using like substructure of support to ceramic s crown used in the market today. The addition of Lanthanum oxide (frit A) and calcium oxide (frit B) was made in attempt to increase the viscosity of LZSA and to reduce fusion temperature. The frits were put over samples of alumina and took to the tubular oven to 1400ºC under vacuum for two groups (groups 1 and 2). For another two groups (groups 3 and 4) it was made a second infiltration, following the same parameters of the first. A fifth group was utilized like group of control where the samples of pure alumina were not submitted to any infiltrating process. Glasses manifested efficient both in quality and results of analysis of mechanic resistance, being perfectly compatible with oral environment in this technical requisite. The groups that made a second infiltration had he best results of fracture toughness, qualify the use in the oral cavity in this technical question. The average of results achieved for mechanic resistance to groups 1, 2, 3, 4 and 5 were respectively 98 MPa, 90 MPa, 144 MPa, 236 MPa and 23 MPa

Construção de um aparato experimental para monitoramento in situ da deposição de filmes finos de titânio por magnetron sputtering

The technique of surface coating using magnetron sputtering is one of the most widely used in the surface engineering, for its versatility in obtaining different films as well as in the micro / nanometric thickness control. Among the various process parameters, those related to the active species of the plasma are of the most fundamental importance in the mechanism and kinetics of deposition. In order to identify the active species of the plasma, parameters such as gas flow, pressure and density of electric power were varied during titanium coating on glass substrate. By flowing argon gas of 10, 20, 30, 40 and 50 sccm (cubic centimeters per minute) for each gas flow a sequential scan of the electric current of 0.10, 0.20, 0.30, 0.40 , 0.50 A. The maximum value of 0.50 A was chosen based both on literature data and on limitations of the equipment. The monitoring of plasma species present during the deposition was carried out in situ by the technique of optical emission spectroscopy (OES) through the spectrometer Ocean Optics USB2000 Series. For this purpose, an apparatus was developed to adapt the OES inside the plasma reactor to stay positioned closest to the target. The radiations emitted by the species were detected by an optical fiber placed behind the glass substrate and their intensities as a function of wavelength were, displayed on a monitor screen. The acquisition time for each condition of the plain parameters was related to the minima of spectral lines intensities due to the film formed on the substrate. The intensities of different emission lines of argon and titanium were then analyzed as a function of time, to determine the active species and estimate the thickness of the deposited films. After the deposition, the coated glasses thin films were characterized by optical transmittance through an infrared laser. It was found that the thickness and deposition rate determined by in situ analysis were consistent with the results obtained by laser transmittance

Preparação de vidros e vitrocerâmicas de óxidos de metais pesados contendo prata: propriedades ópticas, estruturais e eletroquímicas

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

Crystallization study of the (1-x)Sb2O3-(x)SbPO4 glass system

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Treatment of PVC using an alternative low energy ion bombardment procedure

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

Crystallization kinetics in phosphate sodium-based glass studied by DSC technique

In this work, differential scanning calorimetry (DSC) was used to study the mechanism of crystallization of 5OP(2)O(5-)27.8Na(2)O-16ZnO-6.2Al(2)O(3) glass. DSC measurements were performed on bulk and powdered glasses with different particle size. The curve for bulk glass shows one crystallization peak while powdered glasses presented two distinct crystallization peaks. Based on DSC studies, the activation energies obtained were 336 +/- 6 and 213 +/- 3 U mol(-1), associated with first and second crystallization peaks, respectively. Analyzing the DSC parameters as a function of particle size, the Avrami n parameter suggests that the peak at low temperature may be associated with surface crystallization while the peak at high temperature is associated with bulk crystallization. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Evidence of distinct phase transformations in lithium phosphate glass Li2O-P2O5

The purpose of this work is to study the Li2O-P2O5 glass using the differential scanning calorimetry (DSC) and x-ray diffraction (XRD) techniques to understand the crystallization process in this glass matrix. To study the glass by DSC, screened samples with different particle sizes to resolve the crystallization peaks were used. Both crystallization peaks were attributed to Li6P6O18 and LiPO3 phases. This evidence was corroborated by XRD analysis on glasses annealed at different temperatures in order to crystallize these phases.

Undoped and calcium doped borate glass system for thermoluminescent dosimeter

Borate glasses present an absorption coefficient very close to that of human tissue. This fact makes some borates ideal materials to develop medical and environmental dosimeters. Glass compositions with calcium tetraborate (CaB4O7) and calcium metaborate (CaB2O4), such as the xCaB(4)O(7) - (100-x)CaB2O4 System (0 <= x <= 100 wt%) were obtained by the traditional melting/quenching method. A phenomenon widely known as the 'boron anomaly' was observed in our thermal analysis measurements, as indicated by the increase of T, and the appearance of a maximum value in the composition with 40 wt% of CaB2O4. The Dy doped and Li co-doped 80CaB(4)O(7)-20CaB(2)O(4) (Wt%) glass samples were studied by the thermoluminescence technique. The addition of Dy improved the signal sensitivity in about three times with respect to the undoped glass sample. The addition of Li as a co-dopant in this glass caused a shift to a lower temperature of about 20 degrees C in the main glow peak. The structural analysis of the 80CaB(4)O(7)-20CaB(2)O(4) (wt%) undoped and doped samples were studied through infrared absorption. We have noted an increase in the coordination number of the boron atoms from 3 to 4, i.e., the conversion of the BO3 triangular structural units into BO4 tetrahedra. (c) 2006 Elsevier B.V. All rights reserved.

Corrective eyeglasses and medial canthal basal cell carcinoma: a case-control study

Background Corrective eyeglasses are frequently worn by adults, particularly at older ages. Their lenses and frames provide ultraviolet protection. Medial canthal basal cell carcinomas are infrequent (38%), and their relation with the use of corrective glasses was not yet investigated. Objectives To assess the prevalence of corrective eyeglasses use in individuals with medial canthal basal cell carcinoma. Methods Case-control study using two controls matched by age, gender, and ethnicity for each case. Cases were patients with medial canthal basal cell carcinoma, and controls were patients with basal cell carcinoma elsewhere on the face. The prevalence of major risk variables was estimated and adjusted by conditional multiple logistic regression. Results Fifty cases and 100 controls were assessed. The mean patient age was 69.7 years, and 54% of the subjects were females. No difference regarding the eyeglasses use or use duration was found between groups. However, when visual defects were separately evaluated, eyeglasses for myopia correction were independently associated with lower risk of medial canthal basal cell carcinoma development (OR = 0.26; P = 0.03), what can be related to long term local photoprotection. Conclusion The use of eyeglasses for myopia correction is associated with lower prevalence of medial cantal basal cell carcinoma. Risk-reducing mechanisms should be elucidated.

Condição ocular entre trabalhadores de uma indústria metalúrgica brasileira

OBJETIVO: Avaliar a condição ocular em população de trabalhadores de uma indústria metalúrgica paulista. MÉTODOS: Amostra de 2516 funcionários de uma fábrica na cidade de São Paulo foi submetida a uma avaliação oftalmológica como exame ocupacional periódico. Foi aplicado um questionário e realizado o exame de acuidade visual (Snellen) e teste de Ishihara. Os funcionários com acuidade visual menor que 0,7 ou com diferenças maior que duas linhas ou que apresentassem alguma queixa ocular, passaram por avaliação complementar (biomicroscopia, refração, tonometria e fundo de olho). Prescreveu-se óculos conforme indicação. RESULTADOS: Houve predomínio do sexo masculino (62,5%) e faixa etária de 20 a 29 anos (41%). A maioria não apresentava antecedentes oculares (97,6%) ou sistêmicos (96,6%).A acuidade visual estava acima de 0,7 em 95,5% dos olhos e 84% não utilizavam correção. O diagnóstico final foi exame normal em 55% dos casos, presbiopia em 13.6%, astigmatismo miópico em 10% e hipermetrópico em 7,7% dos indivíduos. Baixa visão foi encontrada em 2,4%, cegueira unilateral em 0,4%, não havendo casos de cegueira ou de deficiência visual entre os trabalhadores. As principais causas de baixa visão foram erros refrativos e ambliopia. CONCLUSÃO: A maioria dos funcionários da indústria pesquisada apresentava exame oftalmológico normal e nenhum deles apresentava cegueira bilateral.

Histomorphometric analysis of tissue responses to bioactive glass implants in critical defects in rat calvaria

The aim of this study was to evaluate the osteogenic behavior of two chemically similar bioactive glass products (Biogran (R) and Perioglas (R)) implanted in critical bone defects in rat calvaria. Thirty-six transfixed bone defects of 8 mm diameter were made surgically in adult male Wistar rats. The animals were distributed equally into three groups: Biogran (GI), Perioglas (GII) and without implant material (control; GIII). The morphology and composition of both bioactive glasses were analyzed by scanning electron microscopy and energy-dispersive spectrometry. Tissue specimens were analyzed at the biological time points of 15, 30 and 60 days by optical microscopy and morphometry, demonstrating biocompatibility for the tested materials with moderate chronic inflammation involving their particles. Bone neoformation resulted only as a reparative reaction to an intentionally produced defect and was limited to the defect's edges. No statistically significant differences among the groups were observed. At the scar interstice, abundant deposits of collagenous fibers enveloping the particles were noted. The present results indicated that the bioactive glasses, under the experimental conditions analyzed, did not show osteogenic behavior. Copyright (c) 2007 S. Karger AG, Basel.

The role of vision in Parkinson's disease locomotion control: Free walking task

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