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Nanofios de Ge : síntese e dispositivos
(Universidade Federal de São Carlos, 2012-03-06) Kamimura, Hanay; Chiquito, Adenilson José; https://lattes.cnpq.br/7087360072774314; https://lattes.cnpq.br/2414357209169841
Abstract In this work, germanium nanowires' based devices were studied and developed and the influence of natural disorder on the electronic properties of these structures was also investigated. Parameters related to the current transport mechanisms, such as electron mobility, localization length and Schottky barrier height were determined. Such investigations were carried out initially by the fabrication of germanium nanowires using the vapour-liquid-solid method with gold nanoparticles acting as catalysts for the growth process. Morphological and structural characterizations were performed to obtain information about the material: the X-ray di_raction analysis showed a good agreement with the cubic structure of germanium and its diamond-like structure; by scanning and transmission electron microscopy it was found samples with diameter from 20 to 150 nm and length up to tens of micrometers. Furthermore, these techniques allowed the observation of an oxide layer on the surface of the nanowires, whose disordered interface originates localized states, which can also be responsible for changes in electronic properties of the system. Di_erent types of devices were developed for the investigation of the electronic transport in germanium nanowires. The experiment performed on each device allowed the analysis of the disorder's influence on the measured properties: electronic transport within the temperature ranges used for the experiments was dominated by the variable range hopping mechanism, characteristic of disordered systems instead of the expected thermal excitation, typical of semiconductor materials. Further confirmation of these data was obtained using transistor devices and the carrier mobility was found to be lower than the commonly observed values for germanium. These data also agree with the fact of disordered systems exhibits low mobility values due to the presence of localized states. Finally, it was used a device specially designed for the study of the metal/nanowires interface characteristics. In order to determine the Schottky barrier height a two barriers model was used (including temperature dependence). The obtained values (from 0.48 to 0.54 eV ) were di_erent from the usual (0.58 eV for germanium/aluminium contact), which also shows and con_rms the presence of localized states at the metal/nanowire interface, following Bardeen's model for the Schottky barrier formation. To complement this analysis theoretical simulation values for Schottky barrier (∼ 0.5 eV ) were calculated taking into account the contribution of surface states. This value corresponding to density of states of 1012 ∼ 1013cm−2eV −1. Comparing both theoretical and experimental Schottky barrier heights, the presence of localized states generated by disorder was confirmed.
Caracterização das camadas formadas pela nitretação a plasma de ferro sinterizado
(Universidade Federal de São Carlos, 2012-03-06) Fontes, Marcos Alves; Nascente, Pedro Augusto de Paula; https://lattes.cnpq.br/1387043320265189
Ion nitriding is a process of thermo-physical-chemical treatment that provides a surface hardening, originated by interstitial diffusion of nitrogen on the ferrous and nonferrous alloys surfaces. Understanding and controlling the formation of the nitrided layer have considerable industrial interest due to the improvements regarding wear, corrosion and fatigue resistances on the metals and their alloys. In this work, it was performed the surface modification in sintered iron samples by ion nitriding process, with a gaseous mixture of 80% vol H2 and 20% vol N2, during times of 3 and 5 hours, using ion nitriding temperature of 500°C, 540°C and 580°C. The samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses, and wear and micro-hardness tests, comparing the results with sintered and steam treatment samples. The results showed that both nitride thickness and wear resistance increased with higher nitriding time and temperature, where the temperature was the variable that most influenced the aforementioned characteristics. The XRD analysis indicated that the nitrided layer near to the surface, for all samples, consisted in a mixture of y-Fe4N and e-Fe3N phases.
A violência contra a mulher e o atendimento prestado às vítimas: a perspectiva do policial civil
(Universidade Federal de São Carlos, 2012-03-06) Migliato-Nunes, Patrícia Tonissi; Brino, Rachel de Faria; https://lattes.cnpq.br/0235133592567485; https://lattes.cnpq.br/7578694439215415
The Women's Police Stations were created to combat and prevent violence against women, enabling act in time to prevent the occurrence or worsening damage to individuals development. However, some observational studies, as well as research conducted with violence women victims, show that the police attendance is unsatisfactory, pronounced by patriarchal customs, which contributes to women do not give continuity to the complaint of a crime committed against them, keeping the violence perpetuation. Therefore, it is socially and scientifically relevant to study surrounds` reality of the civil police and the challenges faced by it. This study aimed to elicit and characterize police officers´ beliefs on violence against women and their conceptions of such violence and the attendance to violence victims. The study included 20 police officers from a medium-sized city in the interior of Brazil. The following instruments were used for data collection: a) Questionnaire on beliefs about domestic violence and b) Questionnaire on the conceptions of police officer about violence against women and the attendance to violence victims. The instruments were applied at two different times. Through instruments were made qualitative and quantitative analysis. The quantitative analysis was obtained with descriptive methods. Qualitative analysis was obtained through defined categories. The outcomes showed that the majority of responses police to the statements of the first questionnaire pointed to a low percentage of inappropriate responses, however, the police officers who participated in the survey had specific beliefs about violence against women with high rates of inadequacy, including blaming the victim for staying in abusive relationship, misconceptions about the effects of violence on child development, blaming the victim for the violence. Although, participants had adequate view with respect to some beliefs, such as: conceptions about women deserve to be beaten and physical abuse to be more threatening than psychological abuse. The beliefs in which police officers had higher rate of inadequate responses can directly affect the attendance to violence women victims. The outcomes also showed domestic violence is most often seen by participants as physical aggression, although the participants demonstrated a good knowledge about the different practices of violence. Additionally, the policemen pointed out some challenges for them to meet the victims of violence, such as lack of training, staff shortages and weakened emotional state of employees who can produce an insufficient treatment. The concluding remarkes points to the need for better training for professionals regarding the issues of violence against women, as well as the development, implementation and evaluation of training courses for such professionals, aiming to fill this gap in their formation.
Tornar-se aluno(a) indígena: a etnografia da escola Guarani Mbya na aldeia Nova Jacundá
(Universidade Federal de São Carlos, 2012-03-06) Marqui, Amanda Rodrigues; Cohn, Clarice; https://lattes.cnpq.br/1714080901123094; https://lattes.cnpq.br/1696584969032916
This dissertation investigates the teaching and learning process and the pedagogical practices of Guarani Mbya child from Nova Jacundá, in the southeast of Pará. Its intent is to comprehend what is to becoming/become (Toren 2004) an indigenous student. The child will be taken as a social actor who is active and a culture producer (Cohn 2005), and we took the school as the place where child become students, like the practice of autopoietic (Toren 1999), therefore, a place which produces meaning to their world. So, my ethnography intents to comprehend how these child produce meaning in the school context and, as indigenous students, how they take the school as a frontier place (Tassinari 2001) where the knowledge is articulated, and the Guarani Mbya way of being and their teaching practices with the knowledge and the pedagogical methods. This ethnography of a Guarani Mbya school will contribute to the comprehension of meaning assigned by child going to school, place where are created new forms of knowledge construction indigenous and non-indigenous in new relations, beyond of those made in their own Guarani learning process.
Clonagem gênica e caracterização de uma enzima tipo-luciferase de coleópteros não bioluminescentes e sua relação com a origem da atividade luminescente
(Universidade Federal de São Carlos, 2012-03-06) Prado, Rogilene Aparecida; Viviani, Vadim Ravara; https://lattes.cnpq.br/3942043373510668; https://lattes.cnpq.br/3202205839573412
Bioluminescence in beetles is dependent on luciferase which evolved from AMP/CoA ligases. The cDNA of a luciferase-like enzime was cloned from the Malpighian tubules of Zophobas morio mealworm (Coleoptera: Tenebrionidae). The gene product of this cDNA displays weak luminescence and it is composed of 528 aminoacids residues with N-terminal and C-terminal sequences signal addressed to smooth endoplasmic reticulum membrane. Although having a low identity (26-32%) with beetle luciferases, this enzyme is a reasonable protoluciferase model to investigate the origin and evolution of beetle luciferases. The luciferin binding site is higly conserved among the beetle luciferases. However, in this protoluciferase of Z. morio, most of these residues of this motif are substituted by others. Using a site-directed mutagenesis survey some of aminoacids residues of this protoluciferase, which are located at correspondent luciferin binding site of luciferases, were replaced by the conserved residues of beetle luciferases. Most of the substitutions had negative effect on the luminescent activity, however, the substitution I327T, which is located in a β-hairpin motif close to the luciferin binding site, improved the luminescence activity. Such substitution indicates the importance of this motif for luciferase activity and indicates a possible route for the evolution of bioluminescence function of beetle luciferase. Since this enzyme is located in the Malpighian tubules, which are involved in excretion and metabolization of carboxylic substrates, this enzyme could be involved to excretion the some type of chemical compound. Regardless of the function the results show that the potential for bioluminescent activity is older and probably arose before the divergences of the Coleoptera bioluminescent families.