Effects of time exposure and low power sonochemical treatment on ZnO mesostructures

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

Design and implementation of wireless sensor networks for impedance-based structural health monitoring using ZigBee and Global System for Mobile Communications

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Piezoelectric transducers assessed by the pencil lead break for impedance-based structural health monitoring

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

Effects of copper vapor laser irradiation (λ = 510.6 nm) on the enamel and dentine of human teeth: An ultra-structural morphologic study

Objective: A morphological and ultra-structural study of copper vapor laser (λ = 510.6 nm) effects on enamel and dentine was performed to show the effects of this radiation. Methods: A total of 15 human molars were cut in half; 15 pieces were separated for irradiation on enamel and 15 for dentine. These two groups were further divided into five experimental groups, including a control group, comprised of three half-sections each, irradiated by a CVL laser with a power of 7 W, a repetition rate of 15,000 pulses/sec and exposed at 500, 600, and 800 msec and 1 sec irradiation times with a 5-sec interval between irradiations. Results: In an ultra-structural SEM exam, we observed that on the enamel surfaces irradiated for 1 sec there was morphological alteration that consisted of catering, flaking, and melting on the surfaces. There was no alteration for the other exposure times. On the dentine teeth irradiated for 1 sec, we observed an evident ultra-structural alteration of melted tissue and loss of morphological characteristics. In the dentine group irradiated by 800 msec, we observed ablation and a partial loss of morphological characteristics. In the dentine groups irradiated by 500 and 600 msec, no alteration was observed. Conclusions: The results showed that irradiation with CVL promoted morphologic changes in the enamel as well as in the dentine and demonstrated a need for future studies in order to establish a safe protocol for further use in the odontological practice.

Effect of heat-moisture treatment on the structural, physicochemical, and rheological characteristics of arrowroot starch

The effect of heat-moisture treatment on structural, physicochemical, and rheological characteristics of arrowroot starch was investigated. Heat-moisture treatment was performed with starch samples conditioned to 28% moisture at 100℃ for 2, 4, 8, and 16 h. Structural and physicochemical characterization of native and modified starches, as well as rheological assays with gels of native and 4 h modified starches subjected to acid and sterilization stresses were performed. Arrowroot starch had 23.1% of amylose and a CA-type crystalline pattern that changed over the treatment time to A-type. Modified starches had higher pasting temperature and lower peak viscosity while breakdown viscosity practically disappeared, independently of the treatment time. Gelatinization temperature and crystallinity increased, while enthalpy, swelling power, and solubility decreased with the treatment. Gels from modified starches, independently of the stress conditions, were found to have more stable apparent viscosities and higher G' and G″ than gels from native starch. Heat-moisture treatment caused a reorganization of starch chains that increased molecular interactions. This increase resulted in higher paste stability and strengthened gels that showed higher resistance to shearing and heat, even after acid or sterilization conditions. A treatment time of 4 h was enough to deeply changing the physicochemical properties of starch.