RESUMO

AIMS: This study proposes to investigate the effects of microwave radiation and its thermal effects, compared to thermal effects alone, on the bioenergetics of mitochondria isolated from mouse liver. METHODS: The main parameters investigated in this study are mitochondrial respiration (coupled states: S3 and S4; uncoupled state), using a high-resolution respirometer, and swelling, using a spectrophotometer. RESULTS: Mitochondria irradiated at 2.45 GHz microwave with doses 0.085, 0.113 and 0.141 kJ/g, presented a decrease in S3 and uncoupled state, but an increase in S4. Conversely, mitochondria thermally treated at 40, 44 and 50 °C presented an increasing in S3 and S4, while uncoupled state was unaltered. Mitochondrial swelling increases as a function of the dose or temperature, indicating membrane damages in both cases. CONCLUSION: Microwave radiation and thermal effect alone indicated different bioenergetics mitochondria response. These results imply that the effects due to microwave in medical treatment are not exclusively due to the increase in temperature, but a combination of electromagnetic and thermal effects.

Assuntos

RESUMO

In this work, over the course of four seasons (12 months), we have monitored the fluorescence quantum efficiency (η) from two sets (S1 and S2) of fresh natural dye extracts from the leaves of Tradescantia pallida purpurea. The natural dye was extracted in aqueous solutions from leaves collected from regions with a predominance of shade (S1) and sun (S2) during the day. The thermo-optical parameter fractional thermal load (φ) was measured using conical diffraction (CD) patterns caused by thermally driven self-phase modulation, for η determination in both sets of solutions. Fluorescence measurements corroborate the CD results, and the η values are, on average, slightly higher (~ 11%) in the summer than in the other seasons for both sets of samples (S1 and S2). In addition, the experimental results are presented using natural dye extracted from Tradescantia pallida purpurea as a fungicide probe in Fusarium solani, Sclerotinia sclerotiorum, and Colletotrichum gloeosporioides fungi. The promising fungicide results obtained for the aqueous natural dye extract were compared with those obtained for other natural dyes and fungi. The fungi tested are of the necrotrophic group and constitute important pathosystems in Brazil, causing diseases in several crops that synthetic fungicides often cannot control or do so with low efficiency.

Assuntos

RESUMO

The effect of CO2-driven ocean acidification (OA) on marine biota has been extensively studied mostly on a single stage of the life cycle. However, the cumulative and population-level response to this global stressor may be biased due to transgenerational effects and their impacts on physiological plasticity. In this study, we exposed adult mussels Mytilus chilensis undergoing gametogenesis to two pCO2 levels (550 and 1200 µatm) for 16 weeks, aiming to understand if prolonged exposure of reproductive individuals to OA can affect the performance of their offspring, which, in turn, were reared under multiple stressors (pCO2, temperature, and dissolved cadmium). Our results indicate dependence between the level of pCO2 of the broodstock (i.e., parental effect) and the performance of larval stages in terms of growth and physiological rates, as a single effect of temperature. While main effects of pCO2 and cadmium were observed for larval growth and ingestion rates, respectively, the combined exposure to stressors had antagonistic effects. Moreover, we found a suppression of feeding activity in post-spawning broodstock upon high pCO2 conditions. Nevertheless, this observation was not reflected in the final weight of the broodstock and oocyte diameter. Due to the ecological and socioeconomic importance of mussels' species around the globe, the potential implications of maternal effects for the physiology, survival, and recruitment of larvae under combined global-change stressors warrant further investigation.

RESUMO

The goal of this work is to investigate the thermal effects of femtosecond laser (fs-laser) ablation for the removal of carious dental tissue. Additional studies identify different tooth tissues through femtosecond laser induced breakdown spectroscopy (fsLIBS) for the development of a feedback loop that could be utilized during ablation in a clinical setting. Scanning Election Microscope (SEM) images reveal that minimal morphological damages are incurred at repetition rates below the carbonization threshold of each tooth tissue. Thermal studies measure the temperature distribution and temperature decay during laser ablation and after laser cessation, and demonstrate that repetition rates at or below 10kHz with a laser fluence of 40 J/cm2 would inflict minimal thermal damage on the surrounding nerve tissues and provide acceptable clinical removal rates. Spectral analysis of the different tooth tissues is also conducted and differences between the visible wavelength fsLIBS spectra are evident, though more robust classification studies are needed for clinical translation. These results have initiated a set of precautionary recommendations that would enable the clinician to utilize femtosecond laser ablation for the removal of carious lesions while ensuring that the solidity and utility of the tooth remain intact.

Assuntos

RESUMO

In this work we demonstrate optical trapping and manipulation of microparticles suspended in water due to laser-induced convection currents. Convection currents are generated due to laser light absorption in an hydrogenated amorphous silicon (a:Si-H) thin film. The particles are dragged towards the beam's center by the convection currents (Stokes drag force) allowing trapping with powers as low as 0.8 mW. However, for powers >3 mW trapped particles form a ring around the beam due to two competing forces: Stokes drag and thermo-photophoretic forces. Additionally, we show that dynamic beam shaping can be used to trap and manipulate multiple particles by photophotophoresis without the need of lithographically created resistive heaters.

RESUMO

The synthesis and fluorescence characterization of a new pyrrole derivative (PyPDG) containing the electron donor-acceptor dansyl substituent is reported. The effects of temperature and solvent polarity on the steady-state fluorescence of this compound are investigated. Our results show that PyPDG exhibits desirable fluorescent properties which makes it a promising candidate to be used as the photoactive material in optical thermometry and thermography applications. Further, the electrochemical and emission properties of polymeric films obtained from the oxidation polymerization of PyPDG are also analyzed.

Assuntos

RESUMO

INTRODUÇÃO: O ultrassom (US) terapêutico atua nos tecidos biológicos por meio da vibração, que é capaz de produzir efeitos fisiológicos térmicos e não térmicos. OBJETIVO: Discutir os parâmetros que afetam o aquecimento dos tecidos biológicos, decorrente da aplicação do US. MATERIAIS E MÉTODOS: Efetuou-se levantamento bibliográfico nas bases de pesquisa ISI WEB e SCOPUS. Foram selecionados os artigos, na língua inglesa, que tiveram como ponto central, o estudo da variação da temperatura após a aplicação do US em humanos. RESULTADOS: Foram observadas variações significativas em relação ao aumento de temperatura tecidual. Para a frequência de 3MHz, ocorre um aumento médio de 2,6 ºC nos tecidos superficiais; e para 1MHz, há um aumento médio de 1,7 ºC em tecidos profundos. Há um maior aquecimento do tecido em relação ao tamanho da ERA (área de radiação efetiva), quanto menor o tamanho maior o aquecimento. Também há um aumento da temperatura em relação às intensidades. Intensidades variando entre 0,5 a 3 W/cm² apresentam um acréscimo significativo de temperatura. Em relação à forma de aplicação, o gel proporciona melhor acoplamento, gerando maior aquecimento com um tempo de aplicação de cinco minutos - o tempo de aplicação deve ser adequado à área de tratamento e à densidade de potência. Entretanto, a velocidade de aplicação parece não modificar o aquecimento até 7-8 cm/s, mesmo que dispositivos diferentes aqueçam em níveis diferentes. CONCLUSÃO: Os parâmetros para a aplicação do US devem ser controlados e ajustados para produzir o aquecimento profundo dos tecidos considerando a variação entre dispositivos.

INTRODUCTION: The therapeutic ultrasound act in biological tissues by means of vibration can produce physiological effects of thermal and non-thermal. OBJECTIVE: To discuss the parameters that affect the heating of biological tissues by ultrasound. MATERIALS AND METHODS: We conducted a literature research based on ISI Web and SCOPUS database. We selected the articles in the English language that have studied the temperature variation after the application of ultrasound in humans. RESULTS: There are significant variations related to tissue-temperature rise. For the 3MHz ultrasound, there is an average increase of 2.6 ºC in superficial tissues, and to the 1MHz US, there is an average increase of 1.7 ºC in deep tissues. There is a higher heating of the treated tissue when an area twice the ERA (effective radiating area) size, the shorter the higher the heating, there is an increase in temperature relative intensities. Intensities ranging from 0.5 to 3 W/cm² have a significant increase in temperature. Regarding the mode of application, the gel provides an improved coupling, generating more heat with an application time of five minutes - the application time depends on the treatment area and power density. However, the speed of application appears to modify the heating up to 7-8 cm/s. Also, different commercial devices produce heat differently. CONCLUSION: Parameters for ultrasound application must be controlled and adjusted to generate deep heating of tissues considering that it may vary among devices.

Assuntos