X-ray studies of annealing in thin-film semiconductors

One of the most important issues in thin-film heterostructures is the nature of the interfaces. In general, their structure is likely to involve some degree of lattice strain, especially when the film is deposited on a mismatched substrate. The evolution of the film stress and its behavior during post-deposition processing is critical for many device applications, in particular where extreme operating conditions are encountered. In this presentation we illustrate the use of real-time x-ray scattering for in-situ annealing studies of semiconductor films, emphasizing the advantages of appropriate x-ray optics and fast area detectors.© 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87810/2/196_1.pd

Asymmetric frequency conversion in nonlinear systems driven by a biharmonic pump

A novel mechanism of asymmetric frequency conversion is investigated in nonlinear dispersive devices driven parametrically with a biharmonic pump. When the relative phase between the first and second harmonics combined in a two-tone pump is appropriately tuned, nonreciprocal frequency conversion, either upward or downward, can occur. Full directionality and efficiency of the conversion process is possible, provided that the distribution of pump power over the harmonics is set correctly. While this asymmetric conversion effect is generic, we describe its practical realization in a model system consisting of a current-biased, resistively-shunted Josephson junction (RSJ). Here, the multiharmonic Josephson oscillations, generated internally from the static current bias, provide the pump drive.Comment: 5+ pages, 4 pages supplement. Expanded and modified discussion, additional references and a new appendix in supplemental material detailing the calculation of Josephson harmonics in the RS

Development of a Soft-Tissue Infection Model in the Cow.

The ultimate goals of this study were to develop and define a subcutaneous tissue chamber as a suitable device for establishing a Pasteurella haemolytica soft-tissue infection model in cattle and to use this model to study the in vivo efficacy and distribution of a potentiated sulfa antimicrobial. Developmental studies resulted in the selection of a suitable tissue chamber design that maximized the chamber penetration of an intravenously administered lipid-soluble drug. This chamber could be sampled with ease and contained enough chamber fluid to allow repetitive sampling. Cytological and chemical investigation revealed that the composition of fluid within chambers approached the theoretical composition of true interstitial fluid as time after implantation increased. Despite an ongoing low-grade chronic inflammatory reaction resulting in fibrous encapsulation of chambers, the vascularity of chamber tissue did not diminish with time after implantation. Pharmacokinetic studies conducted using lipid-soluble agents demonstrated that penetration from blood into chamber fluid could be described by a two-compartment pharmacokinetic model, where tissue chambers matched the description of a deep compartment. Diffusion of nonlipid-soluble agents suggested that the permeability characteristics of the diffusional barrier separating blood and chamber fluid were similar to those of capillary endothelial walls, and that tissue chambers formed true interstitial compartments. Inoculation of Pasteurella haemolytica into tissue chambers resulted in the establishment of a localized subcutaneous infection which was similar to the lung lesions seen in pneumonic pasteurellosis. Tissue chamber penetration of intravenously administered sulfadiazine/trimethoprim increased after infection. Despite the maintenance of chamber antimicrobial concentrations which exceeded minimum bacteriocidal levels established in vitro, the infections were not sterilized. This lack of efficacy was associated with decreased pH and increased protein concentrations in chamber fluid after inoculation. Infection with bovine viral diarrhea virus, which is thought to depress host defenses, had no effect on the response of Pasteurella haemolytica to sulfadiazine/trimethoprim therapy. Observation of responsive antibody titers, bacterial phagocytosis, and high leucocyte viability within Pasteurella haemolytica infected chambers demonstrate that the model can be used to study the response of bacteria to specific concentrations of antimicrobials in the presence of functional host defenses

In situ texture monitoring for growth of oriented cubic boron nitride films

We report evidence for oriented growth of pure-phase cubic boron nitride on silicon (100) substrates. The films are deposited at high temperatures (up to 1200 °C) by reduced-bias ion-assisted sputtering. The growth technique produces highly textured c-BNc-BN films with relatively large grain size (∼1000 Å) and reduced residual stress as the bias voltage is decreased. We have been able to grow thick (up to 2 μm) cubic boron nitride films containing 100% of the cubic phase with the (001) crystallographic axis of c-BNc-BN oriented perpendicular to the surface of the film. We show how reflection high-energy electron diffraction applied to texture monitoring in polycrystalline films can be used as an in situ process control technique that allows texture identification and quantitative characterization of its angular spread. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70633/2/APPLAB-74-7-955-1.pd

Reduced bias growth of pure-phase cubic boron nitride

We report results on an improved growth process for cubic boron nitride (c-BN) films. The films are deposited on a dc-biased silicon substrate using ion-assisted sputtering. First, we grow a BN template layer at a bias voltage which maximizes the sp3sp3 content. After this template layer attains a thickness of ∼500 Å, corresponding to the coalescence of the mosaiclike grain structure, we find that we can reduce the substrate bias to about 50% of its initial value while sustaining pure phase c-BN growth. The reduction in nitrogen ion energy results in a dramatic increase in the growth rate as well as significantly improved film quality. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70645/2/APPLAB-71-14-1969-1.pd

Regional Review on Status and Trends in Aquaculture Development in Europe - 2015

This update considers the wider European region comprising the 43 countries that were the object of the more detailed 2010 review of aquaculture in Europe (Váradi et al., 2011) and in particular notes significant changes related to aquaculture in that region since 2010. Aquaculture production data have been obtained from FAO Fisheries and Aquaculture Department, Fishery Information, Data and Statistics Unit. The most notable development in the period has been the continuing increase in the production of Atlantic salmon (by 43 percent for the period 2009–2014), mainly in the Kingdom of Norway but with significant increases also in the Faroe Islands, the United Kingdom of Great Britain and Northern Ireland and the Russian Federation. Production technologies have undergone significant changes in this period with increasing use of very large scale Recirculating Aquaculture Systems (RAS) for the production of large smolts and in some cases for ongrowing fish to up to 1 kg in fresh water before transfer to sea cages. Despite the continuing increase in production, technical challenges remain, in particular the problem of sea lice infestation; the last five years have seen substantial commercial investment in the production and use of “cleaner fish” as biological controllers of lice numbers and in technology for other non-chemical treatment methods. The next five years are likely to see pilot trials of radical new production systems which are designed to minimise environmental impacts. The production of European seabass and gilthead seabream in cages in the Mediterranean Sea has increased, but the ongoing consequences of the global financial crisis of 2007–2009; and the Eurozone sovereign debt crisis from the end of 2009 have to some extent limited growth in these sectors, particularly in the Hellenic Republic. However the Republic of Turkey, with its relatively fast-growing economy and non-EU status has been less constrained by the economic factors and has seen substantial increases in the production of both species. Throughout Europe there has been continued interest, innovation and investment in small-scale RAS for a variety of species for which strong local markets are perceived to exist (examples include sturgeon, shrimp, barramundi, zander, European sea bass, perch and tilapia). Detailed information is difficult to obtain but the scale of this activity may best be described as “pilot”. There has been a high failure rate in such projects, making short-term significant production growth from this sector unlikely. The prescribed length and remit for this update do not allow for a complete summary of the status of all aquaculture sectors throughout Europe; the terms of reference require a focus on areas of significant change in the last 5 years. So, whilst sectors such as the extensive and semi-extensive production of carp represents the finfish species with the third highest production in the region (238 thousand tonnes in 2014, mainly in the Russian Federation), on the basis of information available to the authors there do not appear to have been significant developments in that sector in the last five years. Consequently, the culture of these species does not feature prominently in this review

In situ thin-film texture determination

A kinematic theory of reflection high energy electron diffraction (RHEED) is presented for textured polycrystalline thin films. RHEED patterns are calculated for arbitrary texture situations and for any general crystallographic orientation that may be encountered in thin-film growth. It is shown that the RHEED pattern can be used as a fast and convenient tool for in situ texture characterization. The approach also permits quantitative extraction of angular dispersion parameters which are useful for optimizing thin-film growth conditions. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69371/2/JAPIAU-85-4-2151-1.pd

Technical Considerations of closed containment sea pen production for some life stages of salmonids

We have investigated the technical and economic use of a closed containment sea pen nursery system for production of larger (circa 1 kg) fish for stocking in conventional cage systems with a view to reducing the duration of the marine on-growing phase in conventional open cages. This modified production strategy would reduce the time of exposure to sea lice, allow the capture of some of the solid waste from the culture operation and potentially allow more efficient use of ongrowing sites as the rate of throughput in those sites could be substantially increasedhttp://www.sarf.org.uk/projects