Automated Source-Detector Positioner for Radiation Detection

The Nuclear Engineering Department at Virginia Commonwealth University has an unmet need for an automated source detector positioner for radiation detection experiments that are carried out in lab work. During radiation data collection in radiation detection systems it is of the utmost importance that radioactive samples are positioned and moved with the highest degree of precision possible. This high degree of precision allows for more meaningful data to be collected. The current methods employed by the Nuclear Engineering Department are not as accurate as they can be due to the fact the the current detection systems are manual. Furthermore they are aligned only by sight and have fixed shelving positions. The figure below is the solution to this issue: An automated Source-Detector Positioner for Radiation Detection. This detection system has been design to have a low tolerance so that radiation samples are always centered in the “Sample holder/clamp” over the radiation detector probe. Two stepper motors move along rods, lifting or lowering the sample holder to the desired position over the radiation detection probe. There is also an optional shielding component for the limitation of radiation emission that improves on the shelving method from previous devices. This is all supported with 3D printed rings and metal rods.https://scholarscompass.vcu.edu/capstone/1208/thumbnail.jp

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Greenhouse gas emissions from saturated riparian buffers and woodchip bioreactors

Nitrogen (N) losses from the Mississippi River Basin contribute to the hypoxic zone in the Gulf of Mexico, and NO3 concentrations in surface waters often exceed the USEPA’s drinking water standard of 10 mg-N L-1. Nitrate from artificial subsurface drainage (tiles) underlying agricultural fields can be a major source of reactive N in surface waters. Reducing N flux from agroecosystems is complex and difficult to manage at the watershed scale, as N management alone will not significant reduce N flux. One method for N removal is enhanced microbial denitrification in edge of field practices. Microbial denitrification is an anaerobic process that reduces NO3 to N2 gas. Nitrogen gas released to the atmosphere in a non-reactive state. However, incomplete denitrification can result in nitrous oxide (N2O) production. Nitrous oxide is the third largest contributor to radiative forcing and global climate change. Furthermore, other forms of anaerobic respiration producing greenhouse gases, like methane, can occur in environments designed for denitrification. The studies presented in this dissertation improve greenhouse gas sampling methodology and advance understanding of the effects of enhanced denitrification technologies on greenhouse gas emissions. The Chamber Automated Sampling Equipment (FluxCASE) to measure soil gas flux was found to be accurate and precise compared to manual sampling and improved sampling efficiency. The FluxCASE system was utilized to maximize coverage of spatial variability associated with gas flux from soil surfaces of saturated riparian buffers (SRBs) and woodchip bioreactors. Nitrous oxide emissions from SRBs were compared to traditional buffers and corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] agriculture. Nitrous oxide emissions from SRBs were similar to traditional buffers and lower than crop fields. Nitrous oxide and CH4 production was measured at three hydraulic retention times (HRTs) from pilot scale (5.8 1.0 1.1 m) woodchip bioreactors. Nitrous oxide production increased with decreasing HRT and CH4 increased with increasing HRT. The lowest HRT had the greatest global warming potential. Edge of field practices designed to enhance microbial denitrification are integral strategies to reduce NO3 loss to surface waters, and have the potential to also reduce greenhouse gas emissions from agricultural landscapes

Oxetanes: Recent Advances in Synthesis, Reactivity and Medicinal Chemistry

The 4-membered oxetane ring has been increasingly exploited for its behaviors, i.e. influence on physicochemical properties as a stable motif in medicinal chemistry, and propensity to undergo ring opening reactions as a synthetic intermediate. These applications have driven numerous studies into the synthesis of new oxetane derivatives. This review takes an overview of the literature for the synthesis of oxetane derivatives, concentrating on advances in the last 5 years up to the end of 2015. These methods are clustered by strategy for preparation of the ring (Sections 3 and 4), and further derivatisation of preformed oxetane-containing building blocks (Sections 5-7). Examples of the use of oxetanes in medicinal chemistry are reported, including a collation of oxetane derivatives appearing in recent patents for medicinal chemistry applications. Finally examples of oxetane derivatives in ring opening and ring expansion reactions are described

Environmental and energy assessment of an aviary laying-hen housing system in the Midwestern United States

The laying-hen industry in the United States has been under pressure to change or modify the conventional housing systems. Traditionally, hens have been kept in conventional cages inside environmentally-controlled buildings. These cages are stacked wire mesh enclosures with mechanized egg collection, feed and water delivery systems. Over the past decade there has been much pressure to improve the welfare of the hens by replacing conventional cages with alternative housing systems. There are a number of alternative housing options under consideration or being used. In the cage free system the birds have access to the floor, but are limited to the inside of a barn. The aviary system monitored in this study is a subset of this cage-free system where a tiered structure is used to increase space allocation to the hen while accommodating more hens (than a single level barn). The aviary system also use mechanized egg collection, feed and water delivery systems similar to traditional barns. When the studies described in this dissertation were started, information on the aviary system seemed quite valuable, but the timeliness of the data has become even more apparent over the last few years. Where some states had previously been dealing with transitions to lower stocking densities (fewer hens per unit of area) or alternative systems, there is now an agreement on the table that may bring this transition to a national level. Because the aviary system is so different from conventional housing, there are questions about the impact and performance of such a system. The most obvious difference in all alternative housing, including aviaries, is the lower stocking density. With the lower stocking density, there are many questions about the correct management of houses, especially in winter. The potential issue with ventilation for indoor air quality at the lower stocking density is the possible need for supplemental heat and its proper distribution in the house. This dissertation looks at this issue from many different angles including ventilation rate, indoor air quality, heat and moisture production of the birds, fuel usage, and the birds\u27 preference for winter temperature-ammonia combinations. With the lower stocking density there is also a concern that the labor and utilities provided on a per bird basis will be higher. Another concern with the systems is that a portion of manure from the birds is held in the house on the floor as litter. The litter on the floor impacts indoor air quality. The ammonia and dust concentrations and emissions were two of the major concerns with regard to the litter. With the aviary system, the birds have the ability to be more active. There are questions about how this activity level impacts the heat and moisture production rates of these birds. Overall, there is very little information on the aviary system in the United States. This dissertation aims to address these questions and concerns

Analyzation of Sandpit Lakes in Grand Island, Nebraska

The oxford dictionary defines “dichotomy” as, “noun: a division or contrast between two things that are or are represented as being opposed or entirely different.” In the context of Grand Island, Nebraska, a dichotomy exists in the development of housing. In the 1900s, sand quarrying began along the railroad in Grand Island. When the sand was dredged up from these quarries, the floodplain began to fill in holes over 5 feet deep, creating man-made lakes. As these lakes grew the sand could no longer be quarried, recreation and housing began to develop on their shores. The housing developments, in particular, created a dichotomy: the design of suburbs - cul de sacs, winding roads, sprawl - began occurring around these partially naturally occurring bodies of water, following the shoreline. Soil, or the organic material, sand, has proven prosperous for the city of Grand Island. Financial benefits of the sand quarrying industry, result in not only profit for the companies and therefore an economic increase in the area, but also for the housing and recreational activities that are developing around the lakes created from the quarries. Due to the increase of housing developments, parks, and fishing lakes, Grand Island has experienced an increase in population as well as a diversity of the surrounding environment in the city. Instead of the arbitrary sprawl of many suburbs, the development of housing follows the curves of man-made lakes. In some instances various lakes were quarried in a random fashion, however, others were quarried with a plan to develop them in the future. Through the analysis of these lakes, different patterns and information have been found and the drawings represent the gradual growth and change of these lakes over time. Ranging from currently quarried lakes to currently developed lakes, the history of each lake is represented

The Influence of Number of Daily Milkings on the Production of Dairy Cows

High-producing Holstein, Jersey, Ayrshire, and Guernsey cows of various ages milked three times daily produced from 39.69 to 52.26 per cent more fat and from 44.98 to 65.18 per cent more milk than cows milked twice daily. When high-producing cows of all breeds milked four times daily were compared with cows milked twice daily, the fat production for the several age classes varied from 110.19 to 127.53 per cent and the milk production from 149.08 to 160.31 per cent greater for those milked four times. Milking high-producing cows four times as compared with three times daily showed an increased fat production ranging from 44.70 to 59.81 per cent, while comparable increases for milk ranged from 51 .99 to 71.79 per cent. There was a slight tendency for additional daily milkings to increase the percentage of fat in the milk. The influence of additional milkings was greatest when carried through the entire lactation period

NURS 230 Effectiveness of Florence Nightingale\u27s Environmental Theory

We have chosen to research the effectiveness of Florence Nightingale\u27s environmental theory

Dairy Calf Care and Management

Calf raising begins before the calf is born. A cow that is healthy and in good physical condition will, in all probability, drop a strong, vigorous calf. The feeding and care of the cow before calving is therefore of the greatest importance for the future development of the calf