The crystal growth and properties op some chalcogenides of zinc and cadmium

The main purpose of the work described in this thesis was to develop techniques for producing boules of ZnSe and ZnS(_x)Se(_1-x) suitable for research purposes. This was accomplished by extending the method that Clark and Woods((^1)) used for CdS to the higher temperatures needed to grow ZnS and ZnS(_x)Se(_1-x) in the range x = 0-0.6. In this system the capsule is connected to a reservoir of one of the components via a narrow orifice to maintain constant growth conditions. The system has been examined theoretically in an attempt to learn more about the actual conditions of growth within the capsule. It was concluded that growth occurs close to stoichiometry with(the ratio of P(_se2)/P(_zn) at the growth face) approximately 0.194 or 1.12 according to the element in the reservoir. Particular emphasis was placed upon the incorporation of manganese into the zinc selenide lattice. Concentrations of the order 300 p.p.m. were obtained when the element was added to the charge and MnCl(_2) was placed in the reservoir. Higher levels of manganese (~1%) were obtained using chemical vapour transport with iodine as the transport agent. Boules of solid solutions, within the range of compositions from ZnSe to ZnSe(_0.4)S(_0.6) were examined using a transmission electron microscope. The dominant crystallographic defects were found to change from thin twins to stacking faults as the amount of ZnS was increased. The origin of the defects was probably post growth stress. Finally, the anomalous photovoltaic effect was discovered in ZnSe needle crystals, and was explained qualitatively in terms of asymmetrical barriers along the polar axis of the crystal

Novel Optical Remote Sensing And Ground-Truthing Of Benthic Habitat Using The Burrow-Cutter-Diaz Plowing Sediment Profile Camera System (Bcd Sled)

The Jefferson Benthic Sled provides video sediment profile imagery of continuous cross-sectional data. Subsurface imaging is achieved by attaching a profile camera prism behind an agricultural plow that extends beneath the plane of the sled skids, slicing through the top 10 to 20 cm of sediment. The plowing video profile provides a high-resolution, real-time: remotely controlled view of the flat side of the plow furrow. Successful continuous profiles of up to 100 m have been collected. The equipment allows immediate characterization of benthic habitats, transition zones, sediment types, sediment oxidation layering, biological resources, and fisheries impact

A Tribute to Thomas M. Church: Exploring Chemical Oceanography in the Coastal Zone-The History and Future

( First paragraph) One can find different historical perspectives on the development of studying the chemistry of oceans as well as names for this study—marine chemistry, chemistry of the sea, marine aquatic chemistry, marine biogeochemistry, or chemical oceanography. It could be argued that chemical oceanography is the most inclusive for an earth science since oceanography itself is an integrated discipline that links the biology, chemistry, geology, and physics together. Regardless of the name, perhaps the first intensive, modern/post-nineteenth century study of the ocean’s chemistry was the GEOSECS Program from ca. 1970–1978. The significance of GEOSECS was that it examined the chemistry of the world’s oceans from nutrients to radionuclides, and even a few trace elements, but in a physical context of ocean circulation (e.g., Craig 1972). Thomas M. Church (Figs. 1 and 2) was ‘‘born’’ into the GEOSECS world, receiving his Ph.D. in 1970 from Scripps Institution of Oceanography in the laboratory of Edward Goldberg with the first examination of marine barite in the world’s oceans. GEOSECS was a ‘‘blue water’’ program, but Tom Church decided to take the road less travelled at the time to examine chemical processes in the coastal zone. The coastal zone has been described, both then and now and always somewhat facetiously, as the ‘‘brown ring around the bathtub,’’ but many would argue that this minimizes its importance since it is here where continental weathering products are primarily introduced to the ocean and where many of these same products are also removed. Primary productivity is at a maximum in coastal waters, and human populations and effects are also concentrated here

Distributions and abundances of Pacific sardine (Sardinops sagax) and other pelagic fishes in the California Current Ecosystem during spring 2006, 2008, and 2010, estimated from acoustic–trawl surveys

The abundances and distributions of coastal pelagic fish species in the California Current Ecosystem from San Diego to southern Vancouver Island, were estimated from combined acoustic and trawl surveys conducted in the spring of 2006, 2008, and 2010. Pacific sardine (Sardinops sagax), jack mackerel (Trachurus symmetricus), and Pacific mackerel (Scomber japonicus) were the dominant coastal pelagic fish species, in that order. Northern anchovy (Engraulis mordax) and Pacific herring (Clupea pallasii) were sampled only sporadically and therefore estimates for these species were unreliable. The estimates of sardine biomass compared well with those of the annual assessments and confirmed a declining trajectory of the “northern stock” since 2006. During the sampling period, the biomass of jack mackerel was stable or increasing, and that of Pacific mackerel was low and variable. The uncertainties in these estimates are mostly the result of spatial patchiness which increased from sardine to mackerels to anchovy and herring. Future surveys of coastal pelagic fish species in the California Current Ecosystem should benefit from adaptive sampling based on modeled habitat; increased echosounder and trawl sampling, particularly for the most patchy and nearshore species; and directed-trawl sampling for improved species identification and estimations of their acoustic target stre

Properties of Char Produced from Pyrolysis of Southern Pine

Bench scale pyrolyses were carried out on southern pine at conditions of 250, 350, 400, 500, and 800 C for 1, 2, and 4 hours in a flowing nitrogen atmosphere at flow rates of 135 and 405 milliliters per minute. Data presented in this paper represent work on the properties of the chars produced under these conditions. Results of oxygen bomb calorimetry, density and specific gravity measurements, carbon and hydrogen analyses, and gravimetric yields were statistically analyzed to determine the influence of process conditions on char properties. In general, char yield and percentage of hydrogen and oxygen decreased, while the carbon percentage increased with increasing temperature

Improved antimicrobial activity of nisin-incorporated polymer films by formulation change and addition of food grade chelator

Aims: The following polymers were developed: polyethylene (PE), a PE and polyethylene oxide (70% PE and 30% PEO; PE + PEO) blend, PE and nisin (PE + nisin), PE, nisin, and EDTA (PE + nisin + EDTA), and PE + PEO with nisin (PE + PEO + nisin). Methods and Results: Of the polymers tested, PE and PE + PEO did not exhibit any antimicrobial activity against Brochothrix thermosphacta (BT); however, PE + nisin, PE + nisin + EDTA, and PE + PEO + nisin did. Beef surfaces were experimentally inoculated with 3·50 log10 cfu/cm2 of BT, vacuum packaged with each of the five polymers, and held at 4°C for 21 d. After 3 d at 4°C, BT was reduced \u3e 1·70 log10 by PE + nisin and \u3e 3·50 log10 with PE + nisin + EDTA or PE + PEO + nisin. By 21 d at 4°C, BT was reduced to 0·30 log10 cfu/cm2 when treated with PE + PEO + nisin. Conclusions: It appears that PE + PEO + nisin or PE + nisin + EDTA were more effective for reducing BT, as compared to polymers composed of PE + nisin. Significance and Impact of the Study: Nisin-incorporated polymers may control the growth of undesirable bacteria, thereby extending the shelf life and possibly enhancing the microbial safety of meats

Improved antimicrobial activity of nisin-incorporated polymer films by formulation change and addition of food grade chelator

Aims: The following polymers were developed: polyethylene (PE), a PE and polyethylene oxide (70% PE and 30% PEO; PE + PEO) blend, PE and nisin (PE + nisin), PE, nisin, and EDTA (PE + nisin + EDTA), and PE + PEO with nisin (PE + PEO + nisin). Methods and Results: Of the polymers tested, PE and PE + PEO did not exhibit any antimicrobial activity against Brochothrix thermosphacta (BT); however, PE + nisin, PE + nisin + EDTA, and PE + PEO + nisin did. Beef surfaces were experimentally inoculated with 3·50 log10 cfu/cm2 of BT, vacuum packaged with each of the five polymers, and held at 4°C for 21 d. After 3 d at 4°C, BT was reduced \u3e 1·70 log10 by PE + nisin and \u3e 3·50 log10 with PE + nisin + EDTA or PE + PEO + nisin. By 21 d at 4°C, BT was reduced to 0·30 log10 cfu/cm2 when treated with PE + PEO + nisin. Conclusions: It appears that PE + PEO + nisin or PE + nisin + EDTA were more effective for reducing BT, as compared to polymers composed of PE + nisin. Significance and Impact of the Study: Nisin-incorporated polymers may control the growth of undesirable bacteria, thereby extending the shelf life and possibly enhancing the microbial safety of meats

Labour migration policy post-Brexit: The contested meaning of regulation by old and new actors

The end of free movement of labour from the European Union represents an unprecedented form of re-regulation of the UK labour market. This study explores how old and new actors engage with the sphere of migration, arguing that not only their economic interests but also different political agendas and meanings of regulation shape dialogue on migration regulation post-Brexit. Our findings suggest moving away from a unilateral, positive view of regulation in work and employment as well as to overcome any artificial distinction between the economic and the social implications of international migration