Nanoclusters have special importance in nanotechnology because of their low dimensionality, which provides electronic, chemical, and magnetic properties that differ from those of the equivalent bulk materials. Suitably controllable self-assembly methods are required in order to incorporate nanoclusters into useful devices. The self-assembly method used in this study employs V-grooves as a template element for nanocluster device fabrication. The V-grooves are fabricated by optical lithography on SiO2/Si wafers and KOH wet etching. Bi clusters deposited on a V-groove form a self-assembled conducting wire. The clusters are produced using an inert gas aggregation source inside an ultra high vacuum compatible system. In order to characterise the assembly process, Bi clusters with different average sizes and velocities are deposited on V-grooves with different widths. The cluster bouncing was found to be the main process in forming the cluster wires. The bouncing angles were smaller than the incident angle, and they are dependent on the cluster size and velocity. For a certain bouncing angle, the wire width reflects the V-groove width because of the fixed bouncing angle. Nanocluster devices were fabricated by depositing the clusters on V-grooves with pre-formed Au/NiCr electrical contacts. The amount of the deposited material required to form an electrically conducting wire was found to be a function of the V-groove width and the wire length. The two point I(V) measurements in the voltage range between -1 and +1V showed linear characteristics for low resistance wires (kΩ), and non-linear characteristics for the high resistance ones (MΩ). The silicon substrate was used as a back gate. Applying a voltage to the gate was found to modify the electrical conduction of the cluster wire. The temperature dependence of the resistance of the nanocluster wires was studied in the temperature range of 4.2-473K, and all of the measured wires showed a negative temperature coefficient of resistance. These measurements allowed a detailed study of the conduction mechanisms through the cluster wires. The study showed that Bi clusters can be used for device fabrication. To size select the clusters prior to using them for the device fabrication, a high transmission mass filter is required. This transmission can be obtained using the von Issendorff and Palmer mass filter if it is operated using the optimum operation conditions. The mass filter consists of two pairs of parallel plates with horizontal openings in Plates 1 and 2, and it operates on the time of flight principle. During this project, the operation conditions of this mass filter were studied using both experiment and simulation. The study showed that the beam deflection angle is a critical factor in optimising the mass filter transmission efficiency. This angle is dependent on the accelerating voltage, ion mass, and the horizontal velocity of the ions. The optimum operation conditions for the mass filter were found and used to study the mass distribution of Pd ions produced by a magnetron sputtering source with variable cluster aggregation length.

Nanoclusters have special importance in nanotechnology because of their low dimensionality, which provides electronic, chemical, and magnetic properties that differ from those of the equivalent bulk materials. Suitably controllable self-assembly methods are required in order to incorporate nanoclusters into useful devices. The self-assembly method used in this study employs V-grooves as a template element for nanocluster device fabrication. The V-grooves are fabricated by optical lithography on SiO2/Si wafers and KOH wet etching. Bi clusters deposited on a V-groove form a self-assembled conducting wire. The clusters are produced using an inert gas aggregation source inside an ultra high vacuum compatible system. In order to characterise the assembly process, Bi clusters with different average sizes and velocities are deposited on V-grooves with different widths. The cluster bouncing was found to be the main process in forming the cluster wires. The bouncing angles were smaller than the incident angle, and they are dependent on the cluster size and velocity. For a certain bouncing angle, the wire width reflects the V-groove width because of the fixed bouncing angle. Nanocluster devices were fabricated by depositing the clusters on V-grooves with pre-formed Au/NiCr electrical contacts. The amount of the deposited material required to form an electrically conducting wire was found to be a function of the V-groove width and the wire length. The two point I(V) measurements in the voltage range between -1 and +1V showed linear characteristics for low resistance wires (kΩ), and non-linear characteristics for the high resistance ones (MΩ). The silicon substrate was used as a back gate. Applying a voltage to the gate was found to modify the electrical conduction of the cluster wire. The temperature dependence of the resistance of the nanocluster wires was studied in the temperature range of 4.2-473K, and all of the measured wires showed a negative temperature coefficient of resistance. These measurements allowed a detailed study of the conduction mechanisms through the cluster wires. The study showed that Bi clusters can be used for device fabrication. To size select the clusters prior to using them for the device fabrication, a high transmission mass filter is required. This transmission can be obtained using the von Issendorff and Palmer mass filter if it is operated using the optimum operation conditions. The mass filter consists of two pairs of parallel plates with horizontal openings in Plates 1 and 2, and it operates on the time of flight principle. During this project, the operation conditions of this mass filter were studied using both experiment and simulation. The study showed that the beam deflection angle is a critical factor in optimising the mass filter transmission efficiency. This angle is dependent on the accelerating voltage, ion mass, and the horizontal velocity of the ions. The optimum operation conditions for the mass filter were found and used to study the mass distribution of Pd ions produced by a magnetron sputtering source with variable cluster aggregation length.

Fusarium head blight (FHB) or head scab, caused by Fusarium graminearum Schwabe [telomorph: Gibberella zeae Schwein.(Petch)], is one of the most destructive diseases of wheat (Triticum aestivum L.) worldwide. Numerous strategies for scab resistance breeding are in use, including phenotypic selection for low severity and marker-assisted selection for resistance QTL. The most destructive consequences of scab are evidenced through a reduction in grain quality, and the presence of mycotoxins, the most common of which is deoxynivalenol (DON). Thus, there is great interest among breeders in selecting for resistance to both of these traits. To this end, a study was devised as follows. In 2010, 20 bulk F3 SRW wheat populations with scab resistant parents in their pedigrees were harvested by population from unreplicated plots near Lexington, KY. The plots were affected by a naturally occurring mild-moderate scab epidemic. The grain was sorted on a USDA/ARS and National Manufacturing Seed Sorter System with color camera according to a calibration that reflected visual differences between asymptomatic grain and grain showing FHB symptoms. This process was repeated in 2011 using grain from plots that had conidial suspension applied at anthesis. In 2012, an unreplicated plot study of the C0, C1 and C2 cycles of selection, inoculated with grain spawn and conidial suspension, was evaluated for Fusarium damaged kernels (FDK) and DON concentration. An additional cycle of selection was conducted by running the bulk grain through the sorter. In October 2012, 4 selection cycles of the 20 populations were planted in a RCB experiment at Lexington and Princeton, KY. Bulk populations were planted in both scab nursery and plots, and C3 accepted and rejected of all populations and derived lines of 2 populations were planted in the scab nursery in Lexington, KY. Some populations had FDK and DON reduction with selection, and some derived lines had either numerical or significant reduction with selection. Although the accepted fraction had non-significant reduction compared with the rejected fraction over the populations, FDK and DON means were obviously lower in accepted than in rejected fractions.

Com a finalidade de avaliar o programa de melhoramento da cana-de-açúcar, este trabalho teve como objetivos: determinar o grau da interação famílias x ambientes (FA); comparar métodos de seleção na etapa inicial em termos de resposta esperada à seleção; e propor o método de seleção sequencial modificado. Para isso, foram avaliados 4752 'seedlings' pertencentes a 33 famílias (irmãs germanas e meia irmãs), em dois locais do Estado de São Paulo, Piracicaba e Jaú. Os caracteres estimados foram altura e diâmetro dos colmos, número de perfilhos, Brix % caldo da cana, toneladas de cana por hectare (TCH) e toneladas de Brix por hectare (TBH). Para validar a resposta esperada à seleção sequencial modificada, 40 famílias foram selecionadas por este método e os clones foram multiplicados até a etapa III do programa de melhoramento, a fim de fornecer a resposta realizada à seleção. Os resultados mostraram interação FA significativa para todos os caracteres avaliados. A opção por uma seleção específica implicou em aumentos de ganhos de 4,1% e 5,8% para TBH, para Piracicaba e Jaú, respectivamente, em relação à seleção de famílias generalistas, ou seja, baseada na média dos dois locais. A seleção sequencial modificada, proposta neste trabalho e a seleção combinada através de índices apresentaram pouca vantagem em relação à seleção massal, na condição de seleção direta (sem avaliação visual). Nessas mesmas condições, a seleção sequencial tradicional e a australiana foram inferiores à seleção massal, em termos de progresso esperado, para todos os caracteres. Incluindo a seleção indireta (com avaliação visual) o método sequencial modificado foi sempre superior à seleção massal, para os principais caracteres avaliados (TCH e TBH). Para os métodos australiano e tradicional, houve vantagem apenas quando a correlação genética entre a avaliação visual e o caráter principal foi igual ou inferior a 0,7. Dessa forma, e devido à dificuldade prática de utilizar índices (seleção combinada), concluiu-se que o método proposto de seleção sequencial modificada é perfeitamente viável, sendo, portanto, recomendado. Na comparação entre as respostas estimada e a realizada com a seleção sequencial modificada, houve concordância dos resultados, na condição de correlação genética igual a 0,62. Isso veio reforçar a confiabilidade das estimativas obtidas no trabalho, bem como assegurar as vantagens do método proposto sobre os demais aqui apresentados. Se considerada uma correlação genética entre o critério de avaliação visual e o caráter principal variando entre 0,5 a 0,7, a superioridade do método proposto em relação ao massal é da ordem de 3% a 5%, em termos de ganho esperado para TCH, em um ciclo de seleção. Para alcançar estes mesmos ganhos com a seleção massal, ter-se-ia que aumentar a população inicial entre 36% a 100%. Alternativamente, mantendo os mesmos tamanhos populacionais, o número provável de clones no final do processo seletivo seria aumentado em 85% a 150%, apenas com a substituição do método de seleção massal pelo sequencial modificado na etapa inicial. / Aiming at the evaluation of the sugarcane breeding program, this study had the following objectives: to determine the degree of the family x environments interaction (FE); to compare selection methods in the initial phase, in terms of expected response to selection, and to propose the modified sequential selection method. For this, 4752 seedlings, originated from 33 families (full-sibs and half-sibs), were evaluated in two sites of the State of São Paulo: Piracicaba and Jaú. The traits evaluated were stalk height and diameter, number of stalks, Brix % cane juice, tons of cane per hectare (TCH) and tons of brix per hectare (TBH). To validate the expected response to the modified sequential selection, 40 families were selected by this method and the clones were multiplied until phase III of the breeding program and the realized gains in selection measured. The results showed significant FE interaction for all evaluated traits. The option for a site specific selection would increase gains by 4.1% and 5.8% for TBH in Piracicaba and Jau, respectively, in relation to the generalized family selections, that is, based on the average of the two sites. The proposed modified sequential selection and the combined selection using indices showed little advantage over the mass selection using direct selection (without visual selection). In these conditions, the traditional sequential selection and the Australian one were inferior to the mass selection, in terms of expected progress, for all traits. Allowing for the indirect selection (with visual selection) the modified sequential method was always superior to the mass for the main traits evaluated (TCH and TBH). The Australian method and the Traditional one, were advantageous in relation to the mass selection only when the genetic correlation between visual selection and the main trait was equal or inferior to 0.7. For this reason, and given the practical difficulty of applying indices (combined selection), it was concluded that the proposed method of modified sequential is perfectly viable and was reccommended. Comparing the estimated and realized response of the modified sequential selection, there was correspondence of results, given rG equals to 0.62. This result confirmed the reliance of the estimates obtained in this study, and assured the advantages of the proposed method over those compared. Considering a genetic correlation (rG), between the visual selection criterion and the main character, varying from 0.5 to 0.7, the superiority of the proposed method over the mass one, varies from 3 to 5%, in terms of expected gain, for TCH in one selection cycle. To obtain these same gains with mass selection, one would have to increase the initial population between 36% and 100%. Alternatively, keeping the same population sizes, the likely number in the end of the selection process would be increased in 85% to 150%, just with the substitution of the method of mass selection by the modified sequential one, in the initial phase.

Com a finalidade de avaliar o programa de melhoramento da cana-de-açúcar, este trabalho teve como objetivos: determinar o grau da interação famílias x ambientes (FA); comparar métodos de seleção na etapa inicial em termos de resposta esperada à seleção; e propor o método de seleção sequencial modificado. Para isso, foram avaliados 4752 'seedlings' pertencentes a 33 famílias (irmãs germanas e meia irmãs), em dois locais do Estado de São Paulo, Piracicaba e Jaú. Os caracteres estimados foram altura e diâmetro dos colmos, número de perfilhos, Brix % caldo da cana, toneladas de cana por hectare (TCH) e toneladas de Brix por hectare (TBH). Para validar a resposta esperada à seleção sequencial modificada, 40 famílias foram selecionadas por este método e os clones foram multiplicados até a etapa III do programa de melhoramento, a fim de fornecer a resposta realizada à seleção. Os resultados mostraram interação FA significativa para todos os caracteres avaliados. A opção por uma seleção específica implicou em aumentos de ganhos de 4,1% e 5,8% para TBH, para Piracicaba e Jaú, respectivamente, em relação à seleção de famílias generalistas, ou seja, baseada na média dos dois locais. A seleção sequencial modificada, proposta neste trabalho e a seleção combinada através de índices apresentaram pouca vantagem em relação à seleção massal, na condição de seleção direta (sem avaliação visual). Nessas mesmas condições, a seleção sequencial tradicional e a australiana foram inferiores à seleção massal, em termos de progresso esperado, para todos os caracteres. Incluindo a seleção indireta (com avaliação visual) o método sequencial modificado foi sempre superior à seleção massal, para os principais caracteres avaliados (TCH e TBH). Para os métodos australiano e tradicional, houve vantagem apenas quando a correlação genética entre a avaliação visual e o caráter principal foi igual ou inferior a 0,7. Dessa forma, e devido à dificuldade prática de utilizar índices (seleção combinada), concluiu-se que o método proposto de seleção sequencial modificada é perfeitamente viável, sendo, portanto, recomendado. Na comparação entre as respostas estimada e a realizada com a seleção sequencial modificada, houve concordância dos resultados, na condição de correlação genética igual a 0,62. Isso veio reforçar a confiabilidade das estimativas obtidas no trabalho, bem como assegurar as vantagens do método proposto sobre os demais aqui apresentados. Se considerada uma correlação genética entre o critério de avaliação visual e o caráter principal variando entre 0,5 a 0,7, a superioridade do método proposto em relação ao massal é da ordem de 3% a 5%, em termos de ganho esperado para TCH, em um ciclo de seleção. Para alcançar estes mesmos ganhos com a seleção massal, ter-se-ia que aumentar a população inicial entre 36% a 100%. Alternativamente, mantendo os mesmos tamanhos populacionais, o número provável de clones no final do processo seletivo seria aumentado em 85% a 150%, apenas com a substituição do método de seleção massal pelo sequencial modificado na etapa inicial. / Aiming at the evaluation of the sugarcane breeding program, this study had the following objectives: to determine the degree of the family x environments interaction (FE); to compare selection methods in the initial phase, in terms of expected response to selection, and to propose the modified sequential selection method. For this, 4752 seedlings, originated from 33 families (full-sibs and half-sibs), were evaluated in two sites of the State of São Paulo: Piracicaba and Jaú. The traits evaluated were stalk height and diameter, number of stalks, Brix % cane juice, tons of cane per hectare (TCH) and tons of brix per hectare (TBH). To validate the expected response to the modified sequential selection, 40 families were selected by this method and the clones were multiplied until phase III of the breeding program and the realized gains in selection measured. The results showed significant FE interaction for all evaluated traits. The option for a site specific selection would increase gains by 4.1% and 5.8% for TBH in Piracicaba and Jau, respectively, in relation to the generalized family selections, that is, based on the average of the two sites. The proposed modified sequential selection and the combined selection using indices showed little advantage over the mass selection using direct selection (without visual selection). In these conditions, the traditional sequential selection and the Australian one were inferior to the mass selection, in terms of expected progress, for all traits. Allowing for the indirect selection (with visual selection) the modified sequential method was always superior to the mass for the main traits evaluated (TCH and TBH). The Australian method and the Traditional one, were advantageous in relation to the mass selection only when the genetic correlation between visual selection and the main trait was equal or inferior to 0.7. For this reason, and given the practical difficulty of applying indices (combined selection), it was concluded that the proposed method of modified sequential is perfectly viable and was reccommended. Comparing the estimated and realized response of the modified sequential selection, there was correspondence of results, given rG equals to 0.62. This result confirmed the reliance of the estimates obtained in this study, and assured the advantages of the proposed method over those compared. Considering a genetic correlation (rG), between the visual selection criterion and the main character, varying from 0.5 to 0.7, the superiority of the proposed method over the mass one, varies from 3 to 5%, in terms of expected gain, for TCH in one selection cycle. To obtain these same gains with mass selection, one would have to increase the initial population between 36% and 100%. Alternatively, keeping the same population sizes, the likely number in the end of the selection process would be increased in 85% to 150%, just with the substitution of the method of mass selection by the modified sequential one, in the initial phase.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Objetivou-se com esse trabalho selecionar bactérias residentes de filoplano de maracujazeiro como possível agente de biocontrole da mancha-bacteriana que tem como agente causal a bactéria Xanthomonas axonopodis pv. passiflorae (Xap) e estudar os mecanismos de ação envolvidos no controle biológico. A primeira etapa de seleção baseou-se em testes in vivo com 224 isolados obtidos a partir de folhas sadias de maracujazeiro amarelo coletadas em pomares comerciais, sendo 102 oriundos do estado de Roraima, 72 do Pará e 50 de São Paulo. Estes foram testados em casa-de-vegetação no controle das bactérias fitopatogénicas originadas dos estados de Roraima (Xap-RR), São Paulo (Xap-SP) e Pará (Xap-PA). Após esta etapa, foram selecionados os residentes de filoplano RR-46; RR-29; RR-133; RR-98 e RR-14, oriundo de Roraima e SP-11; SP-18; SP-22; SP-48 e SP-28, provenientes de São Paulo devido apresentarem baixos níveis de severidade da doença 2,3; 2,8; 2,9; 3,5; 3,6; 3,2; 3,25; 3,55; 4,25 e 6,25%, respectivamente. Não houve nenhum antagonista detectado como promissor proveniente do estado do Pará. Foram selecionados os isolados RR-14; RR-29; RR-46; RR-98; RR-133; SP-11; SP-18; SP-22; SP-28 e SP-48, para a segunda etapa de seleção. Esta realizada, in vitro onde os isolados foram submetidos aos ensaios para verificação da utilização de fontes únicas de carbono para verificação de sobreposição de nicho, antibiose por difusão em meio de cultura, produção de sideróforos e influencia na atividade da enzima peroxidase na planta. Os resultados demonstraram que os isolados RR-98 e RR-113 foram capazes de competir por nicho somente contra Xap-RR, através da sobreposição de nicho. Na antibiose, por difusão em meio de cultura o isolado RR-29, foi capaz de inibir três isolados de Xap, provenientes de RR, SP, PA e o isolado SP-28 inibiu apenas as duas últimas. A produção de sideróforos foi observada somente pelos isolados RR-29 e SP-28. Nenhum antagonista foi capaz de influenciar no aumento da atividade de peroxidases nas plantas de maracujazeiro o que indica que não são capazes de induzirem resistência. A sobreposição de nicho, competição por ferro e/ou antibiose são fatores que explicam a capacidade de controle da mancha-bacteriana, mediadas pelos isolados RR-98 e RR-133, RR-29 e SP-28. / The mass selection in vivo is a step of great importance that there be no targeting of biological control mechanisms involved, but only about the efficacy of the biocontrol agent. The objective of this work was to select residents phylloplane bacteria passion fruit as possible biocontrol agent of bacterial spot which is the causal agent Xanthomonas axonopodis pv. passiflorae. 224 isolates were obtained from healthy leaves of yellow passion fruit collected from commercial orchards, and 102 from the state of Roraima, 72 from Pará and 50 from São Paulo. The isolation was done using a half of definitive leave soaked in sterile saline (0.85% NaCl) with 0,3% Tween 80 and maintained in a shaker for 20 minutes, followed by serial dilutions and seeding in Petri dishes containing culture medium 523. Four steps to select for isolates of Roraima, three for isolates from São Paulo and three isolates from Pará were conducted in greenhouse so there would be a confirmation of the antagonistic efficacy of these isolates. Disease severity ranged between 1,1% and 15,3% for isolates from Roraima, 1,15% to 27,5% for isolates from São Paulo and 1,5% to 36,4% for isolates Pará were selected residents phylloplane RR-43, RR-29, RR-133, RR-98 and RR-14, derived from Roraima and SP-11, SP-18, SP-22, SP-48 and SP-28, coming from São Paulo because they presented low levels of disease severity 2,3; 2,8; 2,9; 3,5; 3,6; 3,2; 3,25; 3,55; 4,25 and 6.25%, respectively. There was no antagonist detected from Pará. Were selected isolates RR-43, RR-29, RR-133, RR-98, RR-14 SP-11, SP-18, SP-22, SP-48 and SP-28, for in vitro assays.