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Energy Transfer Efficiency (energy + transfer_efficiency)
Selected AbstractsSynthesis and Energy Transfer Efficiency of FRET Terminators Derived from Different LinkersCHEMINFORM, Issue 9 2004Shiv Kumar Abstract For Abstract see ChemInform Abstract in Full Text. [source] Energy Transfer from Chemically Attached Rhodamine 101 to Adsorbed Methylene Blue on Microcrystalline Cellulose Particles,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2007Hernán B. Rodríguez Rhodamine 101 (R101) was chemically attached onto microcrystalline cellulose and methylene blue (MB) was adsorbed to a sample bearing nearby 6 × 10,7 mol R101 (g cellulose),1. The system was studied by reflectance and emission spectroscopy in the solid state. R101 shows no aggregation in these conditions and, while pure MB builds up dimers on cellulose even at 2 × 10,8 mol g,1, in the presence of R101 no evidence on selfaggregation or heteroaggregation is found up to around 10,6 mol g,1. No exciplex formation is found as well. The overall fluorescence quantum yield measured on thick layers, once re-absorption effects are accounted for, amounts to 0.80 ± 0.07 for pure R101 and decreases steadily on increasing the concentration of MB. Results demonstrate the occurrence of radiative and nonradiative singlet energy transfer from R101 to MB. For thick layers of particles, the combined effect of both kinds of energy transfer amounts to nearly 80% at the highest acceptor concentration, while nonradiative transfer reaches 60% both for thin and optically thick layers. The dependence of nonradiative energy transfer efficiencies on the acceptor concentration is analyzed and the origin of departures from Förster behavior at low acceptor concentration is discussed. [source] Thermodynamic Analysis of Energy Transfer in Acidogenic CulturesENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2008J.-R. Bastidas-Oyanedel Abstract A global thermodynamic analysis, normally used for pure cultures, has been performed for steady-state data sets from acidogenic mixed cultures. This analysis is a combination of two different thermodynamic approaches, based on tabulated standard Gibbs energy of formation, global stoichiometry and medium compositions. It takes into account the energy transfer efficiency, ,, together with the Gibbs free energy dissipation, ,Go, analysis of the different data. The objective is to describe these systems thermodynamically without any heat measurement. The results show that , is influenced by environmental conditions, where increasing hydraulic retention time increases its value all cases. The pH effect on , is related to metabolic shifts and osmoregulation. Within the environmental conditions analyzed, , ranges from 0.23 for a hydraulic retention time of 20,h and pH,4, to 0.42 for a hydraulic retention time of 8,h and a pH ranging from 7,8.5. The estimated values of ,Go are comparable to standard Gibbs energy of dissipation reported in the literature. For the data sets analyzed, ,Go ranges from ,1210,kJ/molx, corresponding to a stirring velocity of 300,rpm, pH,6 and a hydraulic retention time of 6,h, to ,20744,kJ/molx for pH,4 and a hydraulic retention time of 20,h. For average conclusions, the combined approach based on standard Gibbs energy of formation and global stoichiometry, used in this thermodynamic analysis, allows for the estimation of Gibbs energy dissipation values from the extracellular medium compositions in acidogenic mixed cultures. Such estimated values are comparable to the standard Gibbs energy dissipation values reported in the literature. It is demonstrated that , is affected by the environmental conditions, i.e., stirring velocity, hydraulic retention time and pH. However, a relationship that relates this parameter to environmental conditions was not found and will be the focus of further research. [source] Molecular Origin of the Temperature-Dependent Energy Migration in a Rigid-Rod Ladder-Phenylene Molecular Host,ADVANCED MATERIALS, Issue 3 2006H. Wiesenhofer Excitation diffusion is studied in a molecular host doped with a luminescent guest. An atomistic model based on the coupling of the electronic excitations to low-frequency intramolecular vibrations reproduces remarkably well the measured temperature-dependent host-to-guest energy transfer efficiency (see Figure). [source] Influence of maternal mass and condition on energy transfer in Weddell sealsJOURNAL OF ANIMAL ECOLOGY, Issue 3 2006KATHRYN E. WHEATLEY Summary 1Environmental variation influences food abundance and availability, which is reflected in the reproductive success of top predators. We examined maternal expenditure, offspring mass and condition for Weddell seals in 2 years when individuals exhibited marked differences in these traits. 2For females weighing 355 kg there was a positive relationship between maternal post-partum mass (MPPM) and lactation length, but below this there was no relationship, suggesting that heavier females were able to increase lactation length but lighter females were restricted to a minimum lactation period of 33 days. 3Overall, females were heavier in 2002, but in 2003 shorter females were lighter than similar-sized females in 2002 suggesting that the effects of environmental variability on foraging success and condition are more pronounced in smaller individuals. 4There was no relationship between MPPM and pup birth mass, indicating pre-partum investment did not differ between years. However, there was a positive relationship between MPPM and pup mass gain. Mass and energy transfer efficiency were 10·2 and 5·4% higher in 2002 than 2003, which suggests costs associated with a putatively poor-resource year were delayed until lactation. 5Heavier females lost a higher proportion of mass during lactation in both years, so smaller females may not have been able to provide more to their offspring to wean a pup of similar size to larger females. 6MPPM had only a small influence on total body lipid; therefore, regardless of mass, females had the same relative body composition. Females with male pups lost a higher percentage of lipid than those with female pups, but by the end of lactation female pups had 4·5% higher lipid content than males. 7It appears that for Weddell seals the consequences of environmentally induced variation in food availability are manifested in differences in maternal mass and expenditure during lactation. These differences translate to changes in pup mass and condition at weaning with potential consequences for future survival and recruitment. [source] Quantitative FRET Analysis With the E0GFP-mCherry Fluorescent Protein PairPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2009Lorenzo Albertazzi Fluorescence resonance energy transfer (FRET) between fluorescent proteins (FPs) is a powerful tool to investigate protein,protein interaction and even protein modifications in living cells. Here, we analyze the E0GFP-mCherry pair and show that it can yield a reproducible quantitative determination of the energy transfer efficiency both in vivo and in vitro. The photophysics of the two proteins is reported and shows good spectral overlap (Förster radius R0 = 51 Ĺ), low crosstalk between acceptor and donor channels, and independence of the emission spectra from pH and halide ion concentration. Acceptor photobleaching (APB) and one- and two-photon fluorescence lifetime imaging microscopy (FLIM) are used to quantitatively determine FRET efficiency values. A FRET standard is introduced based on a tandem construct comprising donor and acceptor together with a 20 amino acid long cleavable peptidic linker. Reference values are obtained via enzymatic cleavage of the linker and are used as benchmarks for APB and FLIM data. E0GFP-mCherry shows ideal properties for FLIM detection of FRET and yields high accuracy both in vitro and in vivo. Furthermore, the recently introduced phasor approach to FLIM is shown to yield straightforward and accurate two-photon FRET efficiency data even in suboptimal experimental conditions. The consistence of these results with the reference method (both in vitro and in vivo) reveals that this new pair can be used for very effective quantitative FRET imaging. [source] Dimer,monomer equilibrium of human thymidylate synthase monitored by fluorescence resonance energy transferPROTEIN SCIENCE, Issue 5 2010Filippo Genovese Abstract An ad hoc bioconjugation/fluorescence resonance energy transfer (FRET) assay has been designed to spectroscopically monitor the quaternary state of human thymidylate synthase dimeric protein. The approach enables the chemoselective engineering of allosteric residues while preserving the native protein functions through reversible masking of residues within the catalytic site, and is therefore suitable for activity/oligomerization dual assay screenings. It is applied to tag the two subunits of human thymidylate synthase at cysteines 43 and 43, with an excitation energy donor/acceptor pair. The dimer,monomer equilibrium of the enzyme is then characterized through steady-state fluorescence determination of the intersubunit resonance energy transfer efficiency. [source] | |||||||||||||