Structural and electronic properties of Si/Ge nanoparticles

Results of a theoretical study of the electronic properties of (Si)Ge and (Ge)Si core/shell nanoparticles, homogeneous SiGe clusters, and Ge$|$Si clusters with an interphase separating the Si and Ge atoms are presented. In general, (Si)Ge particles are more stable than (Ge)Si ones, and SiGe systems are more stable than Ge$|$Si ones. It is found that the frontier orbitals, that dictate the optical properties, are localized to the surface, meaning that saturating dangling bonds on the surface with ligands may influence the optical properties significantly. In the central parts we identify a weak tendency for the Si atoms to accept electrons, whereas Ge atoms donate electrons.Comment: To appear in Phys. Rev.

Impacts of non-native species in a shallow lake: a simulation modeling approach for restoration and management

There is a long use of models in fisheries and ecology. These models have varying assumptions of how underlying processes occur. Chapter 2 found that violating the assumption of continuous fishing could have consequences for managing harvest of fish populations. In particular, as more fish are harvested in a discrete rather than continuous fashion, parameter estimates of biomass dynamics models assuming continuous harvest can be biased. Accounting for discrete harvest using a semi-discrete biomass dynamics model reduced parameter bias and should be used when discrete harvest is occurring. Extending the exponential semi-discrete biomass dynamics model to an actual population of common carp revealed that the population was increasing. Current levels of commercial harvest were insufficient to suppress biomass. Additionally, the rate of biomass increase was rapid, doubling in approximately three years in the absences of harvest. The effect of rapid biomass increase was further demonstrated by a sensitivity analysis of the model to unintentional underharvest. Sensitivity analyses results suggest the potential for a strong fisherman effect on common carp populations. A framework to assess the minimum amount of harvest needed to maintain common carp biomass was presented. The effects of common carp and zebra mussels in aquatic food webs investigated in Chapter 4 revealed a potential impediment to lake restoration. In particular, zooplankton predation by age 0 yellow bass may limit top down regulation of phytoplankton biomass. Based on mass-balance estimates, age 0 yellow bass were estimated to consumer up to 50% of zooplankton production. The recent invasion of zebra mussel was shown to have an effect on phytoplankton populations, likely compensating for reduced zooplankton abundance. Common carp food web impacts were lower than expected, due to abundant benthic food resources. The potential common carp and zebra mussel ecosystem impacts in the context of ongoing restoration were evaluated in Chapter 5. Simulated changes in common carp biomass had dramatic effects on water quality and recreational fishery yield. This effect was due to increased suspended sediment reducing water transparency, which in turn limited phytoplankton production. This also limited any effect of zebra mussels on water quality by limiting food resources (i.e., edible phytoplankton). In scenarios simulating baseline common carp biomass, increasing or decreasing zebra mussel biomass had positive and negative effects on water transparency respectively. Overall, zebra mussel impacts, positive or negative were limited to baseline common carp biomass scenario classes. Additionally, macrophytes biomass showed a dramatic increase when commercial fishing increased in scenarios of baseline common carp biomass, however this may lead to nuisance levels. Unexpectedly, macrophyte increases in response to increased commercial fishing mortality also stimulated common carp increases as an increased food resource. This in turn reduced simulated water clarity and macrophyte biomass. Results of this study suggest that in-lake processes are a significant component to water quality and recreational fishery yield. Controlling common carp biomass will critical to achieve water quality goals and minimize adverse effects on recreational fishery yield. The recent invasion of zebra mussels to the system will likely positively affect water clarity; however this will be limited by common carp. With common carp biomass controlled, zebra mussels can be expected to clear the water column; however this will reduce pelagic primary production, and require consumers to shift to feeding within benthic food web portions

EXC 008 Aaron Colvin 4-28-2022

Acc #: 756; EXC 008 In this recording, Aaron Colvin is interviewed by Ryan Morini, Michael Campbell, and Willie Dinish in the McCall Library at the University of South Alabama about his experiences in the Excelsior Band. Mr. Colvin discusses being the youngest member of the Excelsior Band. He also reflects on his development as a musician, and the role that music education played in the process—including previously learning under current members of the band. He also offers reflections on the musicianship of the band, and on Excelsior’s legacy

Magnetic particles

Metal oxide containing polymers and particularly styrene, acrylic or protein polymers containing fine, magnetic iron oxide particles are formed by combining a NO.sub.2 -substituted polymer with an acid such as hydrochloric acid in the presence of metal, particularly iron particles. The iron is oxidized to fine, black Fe.sub.3 O.sub.4 particles which deposit selectively on the polymer particles. Nitrated polymers are formed by reacting functionally substituted, nitrated organic compounds such as trinitrobenzene sulfonate or dinitrofluoro benzene with a functionally coreactive polymer such as an amine modified acrylic polymer or a protein. Other transition metals such as cobalt can also be incorporated into polymers using this method

Monodisperse, polymeric microspheres produced by irradiation of slowly thawing frozen drops

Monodisperse, polymeric microspheres are formed by injecting uniformly shaped droplets of radiation polymerizable monomers, preferably a biocompatible monomer, having covalent binding sites such as hydroxyethylmethacrylate, into a zone, impressing a like charge on the droplet so that they mutually repel each other, spheroidizing the droplets within the zone and collecting the droplets in a pool of cryogenic liquid. As the droplets enter the liquid, they freeze into solid, glassy microspheres, which vaporizes a portion of the cryogenic liquid to form a layer. The like-charged microspheres, suspended within the layer, move to the edge of the vessel holding the pool, are discharged, fall and are collected. The collected microspheres are irradiated while frozen in the cryogenic liquid to form latent free radicals. The frozen microspheres are then slowly thawed to activate the free radicals which polymerize the monomer to form evenly-sized, evenly-shaped, monodisperse polymeric microspheres

A food web modeling assessment of Asian Carp impacts in the Middle and Upper Mississippi River, USA

The invasion of non-native fishes has caused a great detriment to many of our native fishes. Since the introduction of invasive carps, such as Silver, Bighead, Common and Grass Carp, managers and researcher have been struggling to remove these species while also hypothesizing the detriment of further invasion. This study developed a food web model of four locations on the Mississippi River and used those models to assess the impacts of two scenarios: carp removal and carp invasion. In the Middle Mississippi River where these invasive carps are already present, the models found that it would take a sustained exploitation of up to 30% of initial biomass over an extended period to remove Grass Carp and up to 90% removal of initial biomass to remove Silver and Bighead Carp. In the locations where Silver, Bighead, and Grass Carp are not yet established (i.e., Pools 4,8, and 13) the invasion of these species could cause declines from 10 to 30% in initial biomass of native fishes as well as already established nonnative invasive species

Proton Association Constants of His 37 in the Influenza-A M218–60 Dimer-of-Dimers

National Institute of Biomedical Imaging and Bioengineering (U.S.) (EB001960)National Institute of Biomedical Imaging and Bioengineering (U.S.) (EB002026)National Institute of Biomedical Imaging and Bioengineering (U.S.) (GM094648