Effect of dental tissue conditioners and matrix metalloproteinase inhibitors on type I collagen microstructure analyzed by Fourier transform infrared spectroscopy

This study aimed to evaluate the chemical interaction of collagen with some substances usually applied in dental treatments to increase the durability of adhesive restorations to dentin. Initially, the similarity between human dentin collagen and type I collagen obtained from commercial bovine membranes of Achilles deep tendon was compared by the Attenuated Total Reflectance technique of Fourier Transform Infrared (ATR-FTIR) spectroscopy. Finally, the effects of application of 35% phosphoric acid, 0.1M ethylenediaminetetraacetic acid (EDTA), 2% chlorhexidine, and 6.5% proanthocyanidin solution on microstructure of collagen and in the integrity of its triple helix were also evaluated by ATR-FTIR. It was observed that the commercial type I collagen can be used as an efficient substitute for demineralized human dentin in studies that use spectroscopy analysis. The 35% phosphoric acid significantly altered the organic content of amides, proline and hydroxyproline of type I collagen. The surface treatment with 0.1M EDTA, 2% chlorhexidine, or 6.5% proanthocyanidin did not promote deleterious structural changes to the collagen triple helix. The application of 6.5% proanthocyanidin on collagen promoted hydrogen bond formation. (c) 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.

Temperaturas de acionamento de condicionadores de ar e ventiladores

Este trabalho apresenta os resultados iniciais de uma pesquisa, descrevendo o comportamento de usuários de edifícios de escritórios em relação às temperaturas de acionamento de ventiladores e aparelhos condicionadores de ar. Medições foram realizadas em quatro salas administrativas do Instituto de Arquitetura e Urbanismo de São Carlos – IAU/USP, nas quais foram registradas as temperaturas internas do ar e o momento de acionamento dos referidos equipamentos. Os valores registrados foram comparados à temperatura externa e à faixa de temperaturas de conforto descrita pela norma ASHRAE 55/2004. As temperaturas registradas de acionamento dos aparelhos condicionadores de ar e ventiladores são similares e estão dentro da faixa considerada confortável pela referida norma.

Influence of alloy microstructure on the microshear bond strength of basic alloys to a resin luting cement

The aim of this study was to evaluate the influence of microstructure and composition of basic alloys on their microshear bond strength (µSBS) to resin luting cement. The alloys used were: Supreme Cast-V (SC), Tilite Star (TS), Wiron 99 (W9), VeraBond II (VBII), VeraBond (VB), Remanium (RM) and IPS d.SIGN 30 (IPS). Five wax patterns (13mm in diameter and 4mm height) were invested, and cast in a centrifugal casting machine for each basic alloy. The specimens were embedded in resin, polished with a SiC paper and sandblasted. After cleaning the metal surfaces, six tygon tubes (0.5 mm height and 0.75 mm in diameter) were placed on each alloy surface, the resin cement (Panavia F) was inserted, and the excess was removed before light-curing. After storage (24 h/37°C), the specimens were subjected to µSBS testing (0.5 mm/min). The data were subjected to a one-way repeated measures analysis of variance and Turkey's test (α=0.05). After polishing, their microstructures were revealed with specific conditioners. The highest µSBS (mean/standard deviation in MPa) were observed in the alloys with dendritic structure, eutectic formation or precipitation: VB (30.6/1.7), TS (29.8/0.9), SC (30.6/1.7), with the exception of IPS (31.1/0.9) which showed high µSBS but no eutectic formation. The W9 (28.1/1.5), VBII (25.9/2.0) and RM (25.9/0.9) showed the lowest µSBS and no eutectic formation. It seems that alloys with eutectic formation provide the highest µSBS values when bonded to a light-cured resin luting cement.

Gamasoidosis illustrated: from the nest to dermoscopy

Gamasoidosis (acariasis, avian-mite dermatitis or bird-mite dermatitis) is a challenging diagnosis that is becoming more common because of the frequent use of window air conditioners in tropical countries. These devices may serve as shelters for nests of urban birds such as pigeons. Dermatologists should become familiar with this infestation to establish the correct diagnosis and treatment.