Photoacoustics
Mostrando 1-6 de 6 artigos, teses e dissertações.
-
1. Desenvolvimento de um sistema de detecção fotoacústico utilizando dois microfones: aplicações em medidas de difusividade térmica / Developing of a photoacoustic detection system using two microphones: applications in thermal diffusivity measurements
Neste trabalho, desenvolveu-se um sistema de detecção fotoacústico para medidas simultâneas e independentes dos sinais fotoacústicos dianteiro e traseiro, utilizando dois microfones e um único feixe de excitação. Utiliza-se a diferença de fase entre estes sinais para a determinação da difusividade térmica de materiais, com base na abordagem teór
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 06/09/2011
-
2. Composition of carotenoids and anthocyanins from acerola : stability and antioxidant activity of anthocyaninc extracts from acerola and açai in model-systems. / Composição de carotenoides e antocianinas em acerola : estabilidade e atividade antioxidante em sistemas-modelo de extratos antocianicos de acerola e de açai.
Natural pigments, such as anthocyanins and carotenoids, are responsible for the colors found in foods, influencing its visual aspect, which is considered the main attribute for the acceptance and preference of a food product. At the same time, these pigments show important biological functions and actions, being considered human health promoters. The associa
Publicado em: 2006
-
3. Volume and enthalpy changes in the early steps of bacteriorhodopsin photocycle studied by time-resolved photoacoustics.
We have studied the photoinduced volume changes, energetics, and kinetics in the early steps of the bacteriorhodopsin (BR) photocycle with pulsed, time-resolved photoacoustics. Our data show that there are two volume changes. The fast volume change ( < or = 200 ns) is an expansion (2.5 +/- 0.3 A3/molecule) and is observed exclusively in the purple membrane (
-
4. Photoacoustic Analysis Indicates That Chloroplast Movement Does Not Alter Liquid-Phase CO2 Diffusion in Leaves of Alocasia brisbanensis12
Light-mediated chloroplast movements are common in plants. When leaves of Alocasia brisbanensis (F.M. Bailey) Domin are exposed to dim light, mesophyll chloroplasts spread along the periclinal walls normal to the light, maximizing absorbance. Under high light, the chloroplasts move to anticlinal walls. It has been proposed that movement to the high-light
The American Society for Plant Biologists.
-
5. Photosynthetic Responses of Leaves to Water Stress, Expressed by Photoacoustics and Related Methods 1: II. The Effect of Rapid Drought on the Electron Transport and the Relative Activities of the Two Photosystems
The effect of rapid dehydration of detached tobacco leaves (Nicotiana tabacum L.) on the photochemical apparatus of photosynthesis was studied in vivo by a combination of methods: photoacoustics, chlorophyll a fluorescence, and cytochrome f difference spectroscopy. It was shown that the inhibition of gross O2 evolution was mainly caused by inactivation of PS
-
6. Photosynthetic Responses of Leaves to Water Stress, Expressed by Photoacoustics and Related Methods 1: I. Probing the Photoacoustic Method as an Indicator for Water Stress in Vivo
The effect of leaf desiccation on the photosynthetic activities in vivo was probed by the photoacoustic method. The aim of this research was: (a) To study the photoacoustic signal per se in varied conditions in order to develop this tool as a probe for stress conditions in vivo. (b) To obtain results pertaining to electron transport activities in vivo, and c