Vacuum field emission devices have become a promising candidate for emerging display technology due to their interesting properties compared to conventional thermionic emission devices that require high temperature and power to operate. Unlike thermionic emission, field emission devices can induce the electrons to emit at low temperature; sharp and thin emitters on the cathode are desired in order to increase the field emission. Many candidates from other research groups, such as Carbon Nanotubes (CNTs), SiC and ZnO, appear to have high field emission, but their complicated fabrication processes are the drawback. The silicon nanowhiskers produced by Geological & Nuclear Sciences (GNS) using Electron-Beam Rapid Thermal Annealing (EB-RTA) are an alternative material that is fast, inexpensive and uncomplicated to produce. They are based on the thermal desorption of silicon oxide, which forms silicon nanowhiskers on the silicon wafer in a short duration. Field emission diode structures on Silicon on Insulator (SOI) wafers were fabricated in order to investigate the field emission due to these GNS silicon nanowhiskers. An uncomplicated fabrication process using photolithography and etching process was developed. Electron beam lithography (EBL) was also used to create the different feature sizes directly onto the SOI wafer. The silicon nanowhiskers grown on these structures are as high as 35 nm with density distribution up to 30 µm⁻¹. The electrical characteristics of these devices are diode-like when the voltage range from -40 V to 40 V is applied. The best samples produced an emitted current as high as 2 mA, which is suitable for many applications, such as flat panel displays, x-ray sources and high frequency devices. However, in some cases, the diode structures failed to show the diode-like characteristics, perhaps as a result of bad contact connections or the emitters have been worn out after applying high voltage for some time. Device life time and stability were also considered and investigated via a number of electrical measurements for a period of time as long as one hour in this study. Even though these nanowhiskers have shown promising results, there are still many aspects to be considered to improve the experiments, such as the vacuum system and better contacts.

The use of vacuum coating is mostly limited to production of high fat containing extruded aqua and pet diets. The physical characteristics of extrudates are favourable for vacuum coating due to their high porosity and durability. However, with pelleted feed for broilers, there are potentially several opportunities, but there are also challenges; these are explored here. The opportunities identified were inclusion of high level of oils, protected delivery of feed additives (e.g., enzymes, probiotics, vaccines, etc.), improved and safe use of offensive feed additives and improvement of shelf-life of feed and additives. Challenges include the relatively high density of pellets (low porosity) which limits liquid infusion, increased processing cost and decreased feed throughput. However, feed ingredients selection and alternating processing variables (temperature, moisture, die specifications etc.) were deemed to overcome the challenges of low porosity. Three experiments were conducted to evaluate the use of vacuum coating in pelleted feed. In the first experiment, the effect of particle size on post-pellet oil absorption (OA), porosity, pellet durability index (PDI) and bulk density were investigated. The three particle sizes for three grains (wheat, barley and corn) were pelleted using a 4.7 mm die to get whole grain (WP), coarse (CP), and fine (FP) grind pellets. The pellets were coated with 15% canola oil without (VC-) and with (VC+; 0.3 bar) vacuum coating. The grain type was found to have a significant effect on the particle size when ground through either fine (3.2 mm) or coarse (6.4 mm) screen. With coarse grinding, the mean particle size was 1896, 1290 and 1057 µm, respectively for barley, wheat and corn; with fine grinding, the mean particle size was 1153, 767 and 732 µm, respectively. Porosity of CP from wheat and corn was significantly (P<0.01) higher than WP and FP. For barley, there was no difference in porosity of CP and FP but both were significantly higher than WP. For wheat, OA of CP was highest (P<0.01), but no significant difference was found between FP and WP. However, for barley, higher OA was found in FP followed by CP and WP. In corn, OA of CP was higher than for FP or WP. Vacuum coating (VC+) improved (P<0.01) OA of all pellets compared to VC-. Porosity was positively correlated with OA and negatively correlated to PDI and bulk density. Overall, the first experiment suggested that alteration of particle size and grain type could be the options for improving the oil absorption by vacuum coating. A second experiment was conducted to observe the effect of enzyme addition method (EAM; E-, without enzyme; PreE+, Pre-pellet addition of enzyme; PosE+, post-pellet addition of enzyme), conditioning temperature (CT; 65 or 95°C) and coating method (CM; VC- or VC+) on broiler performance when fed wheat-rye-based diets. Enzyme addition (pre or post-pellet addition in comparison to without enzyme) significantly improved (P<0.01) the body weight at 21 and 35d. Higher CT (95°C) improved feed conversion ratio (FCR) in both starter (P<0.01) and grow/finish phase (P=0.04) and PDI of both starter and grow/finish pellets (P<0.01) when compared to low CT (65°C). Vacuum coating did not have any effect on the diet extract viscosity, animal performance or digesta viscosity in either of the phases. However, with post-pellet vacuum coating, there was high retention of xylanase activity after processing. Vacuum coating significantly (P<0.05) reduced the relative length of small intestine of broilers at 21d but not at 35d. In the third experiment, broiler grow/finish diets were stored in an incubator (37°C) to see if vacuum coating can improve the shelf-life of feed. The results showed post-pellet vacuum-coated pellets retained higher enzyme activity after 15 days of storage. Although no effect of vacuum coating on animal performance was observed, vacuum coating was able to protect the enzyme during processing and storage. Further work needs to be done to translate these benefits to improve animal performance, which might be achieved using various vacuum coating and processing conditions, and bioactives.

No description available.

Thesis (M.Sc.). / Written for the Dept. of Bioresource Engineering. Title from title page of PDF (viewed 2007/08/30). Includes bibliographical references.

Thesis (M.S.)--Texas State University--San Marcos, 2008. / Vita. Includes bibliographical references (leaves 61-63). Also available on microfilm.

Thesis (M.S.)--Ohio University, November, 1997. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, November, 1995. / Title from PDF t.p.

Thesis (M.S)--Florida State University, 2004. / Advisor: Dr. Hui Li, Florida State University, College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed May 20, 2005). Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 151-152).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.