MAPEAMENTO DE PATOLOGIAS EM SISTEMAS DE REVESTIMENTO CERÂMICO DE FACHADAS

O estabelecimento do uso placas cerâmicas em revestimentos externos data do século XIII. Atualmente, o uso de revestimentos cerâmicos em fachadas está espalhado por todo o mundo e a principal causa desta extensiva utilização são suas propriedades e aspectos estéticos. Um desenho esquemático do sistema de revestimento cerâmico de fachada atualmente adotado no Brasil e bastante difundido no mundo está representado na Figura 1. É utilizado um sistema aderido no qual as placas cerâmicas são aplicadas utilizando argamassa colante industrializada sobre uma camada de argamassa de regularização (emboço), previamente executada sobre os elementos de concreto/aço e alvenarias que compõem, respectivamente, a parte estrutural e de vedação das edificações. As juntas entre as placas são preenchidas com argamassa de rejuntamento industrializada. Outros componentes importantes deste sistema são as juntas de movimentação, dessolidarização e estruturais projetadas para alívio das tensões acumuladas na edificação e no próprio sistema de revestimento

Microencapsulation of casein hidrolysates in lipospheres for debittering flavor: physicalchemistry and sensorial evaluation

In several studies the nutritional value of enzymatic protein hydrolysates has been related to their small peptide contents, especially di- and tripeptides. However, a disadvantage found in the enzymatic process is the development of a bitter taste, which is one of the main obstacles for using the hydrolysates in dietetic formulations and also seems to be associated to the exposition of buried hydrophobic groups. The methods proposed in the literature to solve this problem show some disadvantages, like the reduction of the nutritional value of these preparations. In this work, a new methodology based on the encapsulation in lipospheres was developed, in order to debittering casein hidrolysates obtained by using papain. The second derivative spectrophotometry (SDS) was used for the first time, for measuring the entrapment efficiency of protein hidrolysates and the results were around 66%. This microencapsulation system showed to be an efficient technology to reduce the hydrophobicity and the bitter taste of casein hidrolysates. The scanning electronic microscopy revealed the spherical morphology of this microcapsules, and the measurement of the lipid oxidation indicated a good chemical stability in a period of time up to 60 days.A hidrólise enzimática de proteínas pode levar ao desenvolvimento de sabor amargo, associado à liberação de grupos hidrofóbicos. Neste trabalho, desenvolveu-se uma nova metodologia, baseada no encapsulamento em lipoesferas, para mascarar o sabor amargo de hidrolisados de caseína obtidos pela ação da papaína. Além disso, utilizou-se a espectrofotometria derivada segunda (EDS), como método de determinação da taxa de encapsulamento de hidrolisados enzimáticos de proteínas, e as amostras analisadas apresentaram valores em torno de 66%. Este microencapsulamento mostrou ser uma tecnologia eficiente para reduzir a hidrofobicidade e o sabor amargo de hidrolisados de caseína. A análise por microscopia eletrônica de varredura revelou a morfologia esférica das microcápsulas e a medida da oxidação lipídica mostrou boa estabilidade química por período de até 60 dias

Synthetic tooth enamel: SEM characterization of a fluoride hydroxyapatite coating for dentistry applications

An alternative to etching enamel for retention of an adhesive is to grow crystals on the enamel surface. The potential advantages of crystal growth include easy procedure and less damage to the enamel. These crystals retain the adhesive or are the actual dental restoration. In this work, a paste of synthetic enamel was used to grow crystals of fluoride hydroxyapatite (F-HA) onto the human tooth surface. This technique can be used for several dentistry applications like enamel whitening, strengthening and restoration of early carie lesions. The low cost of reagents and simplicity of the technique along with the biocompatibility of the paste render possible the utilization on the market. The samples were prepared through the application of the paste by the incremental technique. The results obtained by scanning electron microscope (SEM)/EDX have indicated the deposition of a homogeneous layer of calcium phosphate that was grown onto the enamel substrate. The average thickness of the deposited film was in the range of 50-100 µm and with a similar density from the natural enamel observed by radiographic images

Low-cost processing technology for the synthesis of calcium phosphates/collagen biocomposites for potential bone tissue engineering applications

In the present study two novel composites of Calcium phosphates (CaP) and Collagen (COL) were synthesized, hydroxyapatite/Collagen (HA/COL) and hydroxyapatite-btricalcium phosphate/COL (HAbTCP/COL). Collagen was extracted from bovine pericardium submitted to enzymatic digestion and purification by ion-exchange chromatography yielding high purity grade type I collagen. Biocomposites of HAP/COL and HAbTCP/COL were produced with a calcium phosphate/COL ratio of 80/20 (wt. (%)) and were characterized by chemical analysis, light microscopy and scanning electron microscopy, X ray diffraction and FT-infrared spectroscopy. SEM results of the CaP powders showed agglomerates of particles at the nanometric size range with predominantly columnar shape and average chemical composition of [Ca/P] = 1.67. FTIR analysis of collagen has confirmed the major vibrational bands associated with chemical groups like amides and hydroxyls usually found in proteins. SEM micrographs have indicated that both morphological and structural features and chemical composition of the composites were very similar to their precursors, collagen and calcium phosphate components. SDS-PAGE characterization results of protein extracted and purified has showed that bovine type I collagen was successfully obtained. Finally, the biocomposites presented a homogeneous aspect with the calcium phosphate particles aggregated to the collagen fibers. Hence, the novel developed biocomposites have high potential to be used for rebuilding small lesions in bone tissue engineering

Chemsensor of NO2 gas based on porphyrin of 5, 10, 15, 20-tetraphenylporphyrin LB films and LS films

The sensitivity of 5, 10, 15, 20-tetraphenylporphyrin (H2TPP) to the presence of NO2 gas in diluted solutions and in Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) films was investigated by UV-visible spectroscopy. The shift of Soret and Q bands were analyzed and the energies involved were calculated. The exposure of LB porphyrin films deposited onto glass slides to NO2 has performed as an active chemsensor with 7000 ppm gas concentration. Furthermore, the UV-vis dichroism absorption results associated with the Soret bands have given evidence of the tilt angle of the macrocycle related to the substrate. H2TPP in LB film was tilted by an angle of 51 ± 5° and in the LS film was tilted by an angle of 36° ± 5° indicating the formation of a preferential organization of the molecular films depending on the deposition method