This thesis reports the fabrication and characterization of long wavelength infrared mercury cadmium telluride (Hg1-xCdxTe) photodiodes and 128x128 focal plane arrays grown on lattice matched cadmium zinc telluride (Cd1-yZnyTe) substrates by metal organic vapor phase epitaxy (MOVPE). The dark current modeling of 33x33 mm2 Hg1-xCdxTe photodiodes has shown the dark current is dominated by trap assisted tunneling under small reverse bias voltages typically used to bias these detectors. The dominant dark current mechanisms under high reverse bias and low forward bias are band&ndash / to&ndash / band tunneling and generation&ndash / recombination, respectively. The photodiodes have yielded a peak 77 K detectivity of 3.2x1010 cm&amp / #8730 / Hz/W with a cut-off wavelength (50%) of 10.92 mm. It has also been found that the 1/f noise current of the detectors at 1 Hz is related to the trap-assisted tunneling current through the empirical relation in=&amp / #945 / TAT(ITAT)&amp / #946 / with &amp / #945 / TAT=7.0 x 10-5 and &amp / #946 / =0.65. In the course of the focal plane array (FPA) fabrication process development work, ohmic contact formation on p-type Hg1-xCdxTe and mesa wet etch were studied in detail. Contacts with chromium, gold, platinum and copper on p-type Hg1-xCdxTe resulted in bad ohmic contacts, which did not seem to improve with annealing. On the other hand a HgTe cap layer on p-type Hg1-xCdxTe resulted in good ohmic contact with acceptably low resistance. Among the etchants studied for mesa etching of the diode structures, Br2/HBr solution yielded the best performance. After developing all of the steps of FPA processing, 128x128 Hg1-xCdxTe FPAs were successfully fabricated and tested in a thermal imager. While thermal imaging was performed with the FPAs, high nonuniformity of the material and low R0A product of the pixels did not allow high sensitivity imaging.

Currently, in the field of reactor physics, there is a drive for high fidelity, numerical simulations of reactors for the purposes of design and analysis. Since the behavior of a reactor is dependent on various physical phenomena, high fidelity simulations must be able to accurately couple these different types of physics. This is the essence of multiphysics simulations. In order to accurately simulate the thermal behavior of a reactor, the physics of neutron transport must be coupled to the fluid flow and solid phase conduction occurring within the reactor. This thesis develops a computational fluid dynamics solver for this purpose. The solver is based on the PCICE solution algorithm and employs cell-centered finite volumes. In addition to the fluid dynamics solver, a newly developed form of conjugate heat transfer is implemented. This implementation tightly couples the physics of solid phase heat conduction with the fluid dynamics in an efficient and consistent manner. Finally, the radiation transport code EVENT is used to provide heat generation data to the fluids solver. Using this fluids solver, several benchmark problems are analyzed and the formulation is validated.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: van Rooijen, Wilfred; Committee Member: Hertel, Nolan; Committee Member: Stacey, Weston

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No presente estudo três concentrações de N-acetil-l-cisteina (NAC) foram avaliadas no diluente equino resfriado a 5°C através da motilidade do sêmen, integridade da cromatina espermática e choque hiposmótico sobre o ejaculado em diluente Kenney na proporção 1:2 com 50% de plasma seminal. O ejaculado de nove garanhões diluído na proporção 1:2 em meio Kenney foi dividido em 4 partes iguais e suplementado com 5,0, 2,5 e 0,5mM de NAC e um grupo não suplementado (0,0mM). As avaliações foram realizadas a fresco (0h), 24 e 48h de resfriamento. A análise de motilidade nos dois experimentos foi avaliada até às 24 horas. No experimento 2, a adição de 0,5 e 5,0mM de NAC resultou em áreas de dispersão da cromatina espermática similares (59,7 e 55,5μM2, respectivamente). Entretanto, a área de dispersão da cromatina no grupo não suplementado (65,3μM2) e com 2,5mM de NAC (52,8μM2) apresentou diferença (P<0,05). O percentual de células com membrana plasmática funcional foi similar entre o grupo não suplementado e o grupo suplementado com 0,5mM de NAC (39,7 e 39,8%, respectivamente), porém superior a NAC 2,5mM (34,5%) e 5,0mM (34,2%). A motilidade progressiva dos ejaculados suplementados com NAC foram similares entre si e somente o grupo NAC 0,5mM (35,2%) apresentou similaridade de células móveis com o grupo não suplementado (36,2%). Os maiores danos à cromatina espermática no sêmen equino diluído com 50% de plasma seminal mantido resfriado a 5°C ocorrem a partir de 24h de resfriamento. A adição de 2,5 e 5,0mM de NAC comprometem a motilidade e a funcionalidade de membrana espermática equina, mas não causa efeito deletério sobre a integridade do DNA. / In this study, three concentrations of N-acetyl- l-cysteine (NAC) were evaluated by sperm motility, membrane functionality (hypo-osmotic test), and sperm chromatin integrity. the hypo-osmotic test showed only 32.4% (P <0.05) of the cells having a functional membrane 12h into the cooling process, while the fresh semen (0h) was 53.5%. The percentage of motile cells decreased within 12h of cooling from 38.9 to 19.7%, with no difference between 12 and 24h of cooling. The tests of sperm chromatin dispersion and hypo-osmotic shock revealed similarities between the periods of cooling at 24 to 48h. In Experiment 2, the nine stallion ejaculates were divided into 4 equal parts, diluted in half with Kenney milk powder supplemented with 5.0, 2.5 and 0.5mM NAC and a group not supplemented (0.0mM). The evaluations were made fresh (0h), 24 and 48h after cooling. The analysis of motility was assessed in all experiments up to 24 hours. In experiment 2, the addition of 0.5 to 5.0mM NAC resulted in areas of similar sperm chromatin dispersion (59.7 and 55.5μM2, respectively). However, the area of the chromatin dispersion between non-supplemented group=0.0mM (65.3μM2) and 2.5mM NAC (52.8μM2) differ (P <0.05). The percentage of cells with plasma membrane function were similar between the supplemented with 0.5mM NAC and non-supplemented (0.0mM) groups with (39.7 and 39.8%, respectively), but higher than 2.5mM (34.5%) and 5.0mM (34.2%). Progressive motility of ejaculates supplemented with NAC were similar, but only the group with 0.5mM NAC which resulted in 35.2% of mobile cells showed similarities with the non-supplemented group (36.2%). The greatest damage to sperm chromatin in equine semen diluted with 50% seminal plasma kept cooled to 5°C was due to 24h cooling. The addition of 2.5 and 5.0mM NAC inhibits the mobility and functionality of the equine sperm membrane, but does not cause a deleterious effect on the integrity of the DNA.

No presente estudo três concentrações de N-acetil-l-cisteina (NAC) foram avaliadas no diluente equino resfriado a 5°C através da motilidade do sêmen, integridade da cromatina espermática e choque hiposmótico sobre o ejaculado em diluente Kenney na proporção 1:2 com 50% de plasma seminal. O ejaculado de nove garanhões diluído na proporção 1:2 em meio Kenney foi dividido em 4 partes iguais e suplementado com 5,0, 2,5 e 0,5mM de NAC e um grupo não suplementado (0,0mM). As avaliações foram realizadas a fresco (0h), 24 e 48h de resfriamento. A análise de motilidade nos dois experimentos foi avaliada até às 24 horas. No experimento 2, a adição de 0,5 e 5,0mM de NAC resultou em áreas de dispersão da cromatina espermática similares (59,7 e 55,5μM2, respectivamente). Entretanto, a área de dispersão da cromatina no grupo não suplementado (65,3μM2) e com 2,5mM de NAC (52,8μM2) apresentou diferença (P<0,05). O percentual de células com membrana plasmática funcional foi similar entre o grupo não suplementado e o grupo suplementado com 0,5mM de NAC (39,7 e 39,8%, respectivamente), porém superior a NAC 2,5mM (34,5%) e 5,0mM (34,2%). A motilidade progressiva dos ejaculados suplementados com NAC foram similares entre si e somente o grupo NAC 0,5mM (35,2%) apresentou similaridade de células móveis com o grupo não suplementado (36,2%). Os maiores danos à cromatina espermática no sêmen equino diluído com 50% de plasma seminal mantido resfriado a 5°C ocorrem a partir de 24h de resfriamento. A adição de 2,5 e 5,0mM de NAC comprometem a motilidade e a funcionalidade de membrana espermática equina, mas não causa efeito deletério sobre a integridade do DNA. / In this study, three concentrations of N-acetyl- l-cysteine (NAC) were evaluated by sperm motility, membrane functionality (hypo-osmotic test), and sperm chromatin integrity. the hypo-osmotic test showed only 32.4% (P <0.05) of the cells having a functional membrane 12h into the cooling process, while the fresh semen (0h) was 53.5%. The percentage of motile cells decreased within 12h of cooling from 38.9 to 19.7%, with no difference between 12 and 24h of cooling. The tests of sperm chromatin dispersion and hypo-osmotic shock revealed similarities between the periods of cooling at 24 to 48h. In Experiment 2, the nine stallion ejaculates were divided into 4 equal parts, diluted in half with Kenney milk powder supplemented with 5.0, 2.5 and 0.5mM NAC and a group not supplemented (0.0mM). The evaluations were made fresh (0h), 24 and 48h after cooling. The analysis of motility was assessed in all experiments up to 24 hours. In experiment 2, the addition of 0.5 to 5.0mM NAC resulted in areas of similar sperm chromatin dispersion (59.7 and 55.5μM2, respectively). However, the area of the chromatin dispersion between non-supplemented group=0.0mM (65.3μM2) and 2.5mM NAC (52.8μM2) differ (P <0.05). The percentage of cells with plasma membrane function were similar between the supplemented with 0.5mM NAC and non-supplemented (0.0mM) groups with (39.7 and 39.8%, respectively), but higher than 2.5mM (34.5%) and 5.0mM (34.2%). Progressive motility of ejaculates supplemented with NAC were similar, but only the group with 0.5mM NAC which resulted in 35.2% of mobile cells showed similarities with the non-supplemented group (36.2%). The greatest damage to sperm chromatin in equine semen diluted with 50% seminal plasma kept cooled to 5°C was due to 24h cooling. The addition of 2.5 and 5.0mM NAC inhibits the mobility and functionality of the equine sperm membrane, but does not cause a deleterious effect on the integrity of the DNA.

O objetivo deste estudo foi testar um sistema de Polietileno para o transporte de sêmen equino refrigerado por um período de até oito horas. Foram utilizados um total de 87 ejaculados de cinco diferentes garanhões, com idade média de 10 anos, sendo três da raça Puro Sangue de Corrida e dois da raça Pônei Miniatura Brasileiro. Os garanhões foram coletados duas vezes por semana utilizando vagina artificial. Após cada coleta, o sêmen foi avaliado a fresco e diluído na proporção 1+1 (diluente + sêmen) com leite desnatado UHT e dividido em quatro alíquotas de igual volume. No grupo controle (GC) o sêmen foi analisado logo após a diluição (zero hora – 0h). Nos demais grupos o sêmen foi mantido por oito horas (8h) em três diferentes sistemas de transporte: Equitainer® (GE), Botuflex®(GB) e Sistema de Polietileno - Refrigerado (SP) ou Não-Refrigerado (SPN). Foram avaliadas a motilidade total, vigor, a integridade de membrana plasmática (CFDA/PI), funcionalidade de membrana plasmática (HOST) e morfologia espermática. No SP não ocorreu diferença estatística em todos os parâmetros avaliados, quando comparado com o GE e o GB (médias da motilidade total = 45,00%, 49,29% e 46,40%; médias do vigor = 2,04, 2,18 e 2,01; médias do CFDA/PI = 71,12%, 73,29%, 71,32; médias do HOST = 39,70%, 41,21% e 39,76%; e médias da morfologia = 80,50%, 82,29% e 81,28%, valores respectivos de cada parâmetro para SP, GE e GB), enquanto o SPN apresentou valores médios inferiores ao GE para todos os parâmetros avaliados (médias da motilidade total = 50,65% e 62,60%; médias do vigor espermático = 1,78 e 2,43; médias do CFDA/PI = 72,56% e 78,30%; médias do HOST = 43,56% e 48,87%; médias da morfologia = 77,17% e 84,82%, respectivamente para SPN e GE). Com base nos dados podemos concluir que o SP foi igual ou não diferiu dos demais sistemas estudados, já o SPN se apresentou inferior aos demais sistemas estudados neste experimento. Portanto, o uso do SP é indicado para o transporte de sêmen refrigerado por oito horas, quando comparado aos demais sistemas estudados neste trabalho. / The aim of this study was to test a polyethylene system to ship equine cooled semen. A total of 87 ejaculates from five different stallions with known fertility, mean age 10 years, were used, being three Thoroughbred and two Miniature Pony horse. The stallions were collected twice a week using an artificial vagina. After each collection the semen was diluted 1+1 (diluent+semen) with UHT skim milk and divided into four aliquots of equal volume, yielding a total of four groups. In the control group (CG) the semen was analyzed immediately after dilution (zero hour - 0h). In the other groups semen was stored for eight hours (8h) in three different transport systems: Equitainer® (EG), Botuflex® (BG) and Polyethylene System - Cooled (PS) or Non-Cooled (NPS). The total motility, vigor, plasma membrane integrity (CFDA/PI), plasma membrane functionality (HOST) and sperm morphology were evaluated. In PS did not occur a statistical difference in all parameters compared with EG and BG (averages of total motility = 45.00%, 49.29% and 46.40%, the average effect = 2.04, 2 18 and 2.01; averages CFDA / PI = 71.12%, 73.29%, 71.32; averages HOST = 39.70%, 41.21% and 39.76%, and the average of morphology = 80.50%, 82.29% and 81.28%, respective values of each parameter to PS, EG and BG), while the NPS showed lower mean values than the EG to all parameters (total motility averages = 50,65% and 62,60%, sperm vigor averages = 1,78 and 2,43; CFDA / PI averages = 72,56% and 78,30%; HOST averages = 43,56% and 48,87 %, morphology averages = 77.17% and 84.82%, respectively for NPS and EG). Based on the results we can conclude that the PS was equal or did not differ from the other systems studied, the NPS already performed lower than the other systems studied in this experiment. Therefore, the use of the SP is indicated for the transport of cooled semen for eight hours as compared to other systems studied in this work.

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