Femtosecond Carrier Dynamics in In2O3Nanocrystals

We have studied carrier dynamics in In2O3nanocrystals grown on a quartz substrate using chemical vapor deposition. Transient differential absorption measurements have been employed to investigate the relaxation dynamics of photo-generated carriers in In2O3nanocrystals. Intensity measurements reveal that Auger recombination plays a crucial role in the carrier dynamics for the carrier densities investigated in this study. A simple differential equation model has been utilized to simulate the photo-generated carrier dynamics in the nanocrystals and to fit the fluence-dependent differential absorption measurements. The average value of the Auger coefficient obtained from fitting to the measurements was γ = 5.9 ± 0.4 × 10−31 cm6 s−1. Similarly the average relaxation rate of the carriers was determined to be approximately τ = 110 ± 10 ps. Time-resolved measurements also revealed ~25 ps delay for the carriers to reach deep traps states which have a subsequent relaxation time of approximately 300 ps

Stable Isotope Composition of Fatty Acids in Organisms of Different Trophic Levels in the Yenisei River

We studied four-link food chain, periphytic microalgae and water moss (producers), trichopteran larvae (consumers I), gammarids (omnivorous – consumers II) and Siberian grayling (consumers III) at a littoral site of the Yenisei River on the basis of three years monthly sampling. Analysis of bulk carbon stable isotopes and compound specific isotope analysis of fatty acids (FA) were done. As found, there was a gradual depletion in 13C contents of fatty acids, including essential FA upward the food chain. In all the trophic levels a parabolic dependence of δ13C values of fatty acids on their degree of unsaturation/chain length occurred, with 18:2n-6 and 18:3n-3 in its lowest point. The pattern in the δ13C differences between individual fatty acids was quite similar to that reported in literature for marine pelagic food webs. Hypotheses on isotope fractionation were suggested to explain the findings

Use of immobilized algicidal bacteria to control natural freshwater diatom blooms

The purpose of this investigation was to assess the possible use of algicidal bacteria in conjunction with an immobilization technique for efficient termination of natural blooms of Stephanodiscus concomitant with minimization of adverse effects caused by a single application of bacteria. The performance of Pseudomonas fluorescens cells immobilized on cellulose sponges (CIS) was compared with that of freely suspended cells (FSC) of the organism at low water temperature (WT) of < 10A degrees C in co-cultures and natural microcosms. In the co-cultures, CIS resulted in more effective lysis of Stephanodiscus, irrespective of similar bacterivore (Spumella sp.) density, and significantly reduced the concentrations of nitrate and soluble reactive phosphorus (SRP), but not that of silicate, compared with FSC. In the microcosms containing natural freshwater, CIS reduced the densities of Stephanodiscus spp. and Aulacoseira spp. but had no effect on other phytoplankton. Compared with FSC, removal of nutrients by the CIS prevented secondary blooms caused by other phytoplankton. Our results indicate that the CIS affords effective protection of P. fluorescens from low WT and heterotrophs, and restrained regeneration of both SRP and nitrate. Thus, it was demonstrated that the CIS may be an attractive alternative to FSC for control of natural blooms.11sciescopu