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Determinação experimental da força de adesão entre partículas e meios filtrantes constituídos de celulose
(Universidade Federal de São Carlos, 2010-05-07)
Faustino, Patrícia Brígida
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Aguiar, Mônica Lopes
;
https://lattes.cnpq.br/0431688649128529
;
https://lattes.cnpq.br/6807169442685729
The influence of particle size, compression velocity, and of the material constituting the substrate on adhesion force between particle and substrate was investigated in this study. The centrifuge technique was applied for compression velocities (press-on) of 500, 1000, and 1500 rpm and detachment velocity (spin-off) of 500 to 14000 rpm. A microcentrifuge (MA 860, Marconi Equipamentos) of maximum rotational velocity of 1400 rpm was used during trials. The velocity of the centrifuge promoted the compression (press-on) and the detachment (spin-off) of particles on the surface of the substrate. Two tubes made of aluminum were placed in the rotor of the microcentrifuge to hold the adapters also made of aluminum. The adapters worked as supports for the substrate containing the particles of the particulate matter. After compression and after each decompression, pictures of the surface of the substrate containing the particles were taken and each image was analyzed in an image analysis program (Image-Pro Plus 6.0) in order to count adhered and detached particles. When it comes to evaluating the influence of particle-substrate adhesion force by using the centrifuge technique, phosphate concentrate (ρp=3.18 g.cm-3) was used as particulate matter. The diameter ranges studied for the particulate matter were of 9 22; 22,1 40; 40,1 54 and 54,1 77 μm. A cellulose filter paper and a cellulose ester membrane were used as substrate. The phosphate concentrate particles were pressed against the surface of the paper filter and of the membrane individually with help of the centrifuge at specific compression centrifuge velocities and, afterwards, the adhesion profile was determined. It was observed that the adhesion force increased with an increase in rotational velocity of the centrifuge applied in the compression and with an increase in particle size of the particulate matter. It was also verified that the adhesion force between the phosphate concentrate particles and the paper filter was higher than that of the membrane, which led to the conclusion that the structural arrangement of filter media had an influence on the detachment process of particles, consequently influencing on adhesion force value.
Professores negros, experiências de discriminação, de racismo e pedagogias anti-racistas
(Universidade Federal de São Carlos, 2010-05-07)
Machado, Lúcia Helena de Assis
;
Silva, Petronilha Beatriz Gonçalves e
;
https://lattes.cnpq.br/0802503359567533
The presente work has a objective the a analysis by the memory and telling of personal and professional experiences of discriminations and racism lived by eight black teachers, for through them to understand the position accepted by the same teachers up against the racial question, or in the school circle or out of it. It also analizes how the discriminatitory experiences contribute in bigger or smaller grade for these teachers build anti-racism strategies or educations with the object to finish with the racial discrimination and prejudice. The position of the teachers varied between a combative position of fight, silence, refuse, face in the personal circle till the build of strategies, even if in the individual fighter field of discrimination.
Potencial alelopático de macrófitas aquáticas e a influência dos fatores ambientais na sua distribuição em um estuário cego
(Universidade Federal de São Carlos, 2010-05-07)
Takao, Leandro Kenji
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Lima, Maria Inês Salgueiro
;
https://lattes.cnpq.br/2171993314203162
;
https://lattes.cnpq.br/9030693363195106
Tropical blind estuaries have a flooding regime that exposes the flora to extreme changes in environmental conditions. Salinity and flooding seem to be the major factors influencing vegetal species distribution in these environments. Aquatic macrophytes are one of the most productive communities and through their metabolism are able to influence aquatic ecosystem. Allelopathic interactions are among the factors that affect phytosociology and are increased under biotic and abiotic stress conditions. The allelopathic potential has been explored for its application as natural herbicide in weed species control. The aim of our study was to evaluate salinity and flooding influence on species distribution, diversity and richness. We also studied and compared allelopathic properties of aquatic macrophyte species and their possible application to inhibit weeds. For this, we studied the macrophytes´ community and its relation with abiotic variables (flooding and salinity) in Massaguaçu River tropical estuary, located in Caraguatuba-SP. We found 54 macrophyte species belonging to 27 families in this environment. The distribution of these species seems to be related to flooding regime and salinity. Species diversity and richness vary with flooding time but not with salinity. Vegetation presents a sequence of heterogeneous communities through saline gradient and flooding categories. Thereby, Massaguaçu River estuary is defined as a double ecocline: lengthwise (between freshwater and seawater) and lateral (between terrestrial and aquatic habitats). We noticed several species with allelopathic potential over lettuce, a bioindicator species, in laboratory experiments with different inhibition potentials. Then, we found significative inhibitory effects of Ipomoea cairica (L.) Sweet extracts on the germination and early development of weed species: B. pilosa, E. crusgalli, E. heterophylla e I. grandifolia. Our results help to understand tropical blind estuarine environment and its floristic compositon, characterizing their vegetable populations, distribution and potential to be explored as an alternative to synthetic herbicides.
O papel dos receptores 5-HT3 da amídala na modulação da ansiedade em camundongos expostos ao labirinto em cruz elevado
(Universidade Federal de São Carlos, 2010-05-07)
Laine, Letícia
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Souza, Azair Liane Matos do Canto de
;
https://lattes.cnpq.br/2352004564367849
;
https://lattes.cnpq.br/2611147467634592
Aversive situations may activate the serotonergic system, which, in turn, emit projections to structures involved in the defense mechanisms such as: septum, hypothalamus, hippocampus, periaqueductal gray and amygdala, producing behavioral alterations that can be characterized as anxiety. Various studies have related the 5-HT3 receptor functions to anxiety-like behaviors. However, serotonin (5-HT) presents a dual role in this modulation. The elevated plus-maze (EPM), based on the rodents natural aversion to open spaces, is one of the most widely employed models used to study anxiety in rodents. Thus, this study investigates the effects of an agonist and an antagonist of 5-HT3 receptors, mCPBG and ondansetron, respectively, on mice exposed to the EPM. Conventional anxiety measures (percentage of open arms entries and percentage of open arms time), locomotor activity (frequency of closed arms entries) and ethological measures related to the risk assessment were registered. The results demonstrated that, in experiments 1 and 2, the intra-amygdala injections of ondansetron (0.3, 1.0 and 3.0 nmol/0.1Ql) and mCPBG (10 and 20 nmol/0.1Ql), produced a decrease and increase, respectively, of the indices of anxiety in mice evaluated on the EPM. In experiment 3, the local ondansetron injection (0.03 nmol/0.1Ql), was able of reverting the anxiogenic effect caused by the mCPBG (10 nmol/0.1Ql). Taken together, these results suggest that the modulation of the 5-HT3 amygdala receptors for the 5-HT receptors in mice, may display an anxiogenic role.
Estudo das propriedades estruturais e de transporte eletrônico em nanoestruturas de óxidos semicondutores e metálicos
(Universidade Federal de São Carlos, 2010-05-07)
Berengue, Olivia Maria
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Chiquito, Adenilson José
;
https://lattes.cnpq.br/7087360072774314
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https://lattes.cnpq.br/1312983845888585
The structural and transport features of oxide nanostructures synthesized by a vapour phase aproach: the VLS and VS methods were investigated in this work. ITO and In2O3 nanowires were characterized by using XRD, HRTEM and FEG-SEM techniques. Both nanostructures were found to be body-centered cubic (bixbyite, point group Ia3) single crystals with a well defined growth direction. Raman spectroscopy was used in order to study the nanowires composition, crystalline character and the role of tin atoms in the In2O3 lattice (ITO) was studied as well. The influence of the structural disorder induced by doping was pointed as the main cause of the break of the selection rules in ITO and it was promptly recognized in the Raman spectrum. The metallic character observed in In2O3 micrometric wires was assigned to the electron-phonon scattering in agreement with the Bloch-Grüneisen theory. ITO samples with different sizes were analysed in the framework of the Bloch-Grüneisen theory and at high temperatures (T > 77 K) they were found to present a typical metallic character. It was observed at low temperatures (T < 77 K) and in small samples a negative temperature coefficient of resistance which is an evidence that quantum interference processes are present. A weak localized character was found in these samples as detected in magnetoresistance measurements. The electron s phase break was associated to the electronelectron scattering (T < 77 K) and the electron-phonon scattering (T > 77 K). The transport measurements in one-nanowire based FET provided data on the electron s mobility and density. Tin oxide nanobelts were also studied and their structural and electrical characterizations were obtained. In this case the association of several structural measurements provided that the samples are rutile-like single crystals (point group P42/mnm) grown by the VS mechanism. The transport measurements provided data on the nanobelts gap energy (3.8 eV) and on the transport mechanisms acting in different temperature ranges. An activated-like process and the variable range hopping were found to be present in different temperature range and additionally the localization length was determined. The influence of additional levels inside the gap caused by oxygen vacancies was studied by performing light and atmosphere-dependent experiments and as a result a photo-activated character was detected. Thermally stimulated current measurements provided evidence that only one level associated to the oxygen vacancies at 1.8 eV seems to contribute to the transport in SnO2 nanobelts. Triclinic single crystalline nanobelts were identified as the Sn3O4 phase and were analyzed by transport measurements. The samples were wide band gap semiconductors and the role of oxygen vacancies was identified by using PL and PC measurements. The semiconductor behavior was confirmed by the electron transport data, which pointed to the variable range hopping process as the main conduction mechanism (55 K < T < 398 K) and data on localization length and on the hopping distance were obtained. The presence of additional levels due to oxygen vacancies and tin interstitials was recognized in the samples by performing photo-activated and thermally stimulated current measurements.
Polarização de spin em heteroestruturas semicondutoras contendo pontos quânticos de InAs
(Universidade Federal de São Carlos, 2010-05-07)
Santos, Ednilson Carlos dos
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Gobato, Yara Galvão
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https://lattes.cnpq.br/7558531056409406
;
https://lattes.cnpq.br/5543466901202809
In this work, we have studied spin polarization of carriers in a resonant tunneling diode GaAs/AlGaAs with InAs quantum dots in the center of the quantum well. We have observed that the photoluminescence of quantum dots depends on applied voltage and light intensity. Our results were explained by the capture of minority carriers (holes) to quantum dot energy levels in the resonant conditions. We have also studied the polarized resolved photoluminescence under magnetic field applied parallel to the tunnel current. We have observed that the degree of circular polarization is voltage-dependent under low voltage and laser intensity condition. We have also observed that the degree of polarization of quantum dots tends to zero for high applied voltages. Our results show that the circular polarization depends on the injection and capture of holes by quantum dots. Finally, we observed that the circular polarization from quantum dots can be voltage and light-controlled and could be interesting for the developing of new spintronics devices.
Estudo experimental e numérico da fluidodinâmica e das transferências de calor e massa em um leito de jorro contínuo: uso da técnica CFD
(Universidade Federal de São Carlos, 2010-05-10)
Rosa, Cezar Augusto da
;
Freire, José Teixeira
;
https://lattes.cnpq.br/2270677706718167
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https://lattes.cnpq.br/6540467268812748
In this work, the transport phenomena, which occur during the drying operation in a continuous spouted bed, are evaluated through experimental data and CFD simulations. Thus, this thesis was divided into three main parts: fluid dynamics, heat transfer and mass transfer. The fluid dynamics of a spouted bed, with continuous solids feeding, was studied through experimental data of static pressure, fountain height and air mass flow rate. A two-fluid two-dimensional model using the Euler-Euler approach was applied to simulate the fluid dynamics of the system. Gidaspow (1992) drag model was used to describe fluid-particle interface forces and the granular kinetic theory (Lun et al., 1984) to predict the solid phase stress. The commercial fluid dynamics code, FLUENT 6.3, was chosen to solve the model equations. The data obtained via CFD compared well with experimental results. In the heat transfer study, the conservation of energy equation was used, in conjunction with the fluid dynamics model, to simulate the heat transfer between the gas and particles in a continuous draft tube spouted bed. Two different Nusselt number correlations (Gunn, 1978; Kmiec, 1980) were used to calculate the heat transfer coefficient between the phases. The simulated results were compared with the experimental data obtained for the fluid temperature in the draft tube and annulus sections of the bed as well as for the solids outlet temperature. The drying simulations were done by coupling the transport phenomena, fluid dynamics, heat and mass transfer. An equation, based on thin layer drying data, was developed for the drying constant, which is a function of the fluid temperature and gas-solids relative velocity. The drying model presented physically consistent results and it seems to be promising for the drying analysis.
O processo transcriativo de São Bernardo de Leon Hirszman
(Universidade Federal de São Carlos, 2010-05-10)
Bozicanin, José Eduardo
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Monzani, Josette Maria Alves de Souza
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https://lattes.cnpq.br/0505156751073470
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https://lattes.cnpq.br/0331116908238067
The purpose of our research was to recoup some of the ideas about the intersemiotic translation of Graciliano Ramos' novel Sao Bernardo (1934) to the cinema. In this masters dissertation we realised the creative genesis of Leon Hirszman's filmmaking processes by following the path traced by the film-maker since the reading of the homonymous novel to the to the writing of an unknown script and posteriorly in his film editing and sonorization approaches.
Viabilidade prática de Bacillus subtilis para controle biológico de Colletotrichum acutatum, agente causal da queda prematura dos frutos cítricos
(Universidade Federal de São Carlos, 2010-05-10)
Corrêa, Francisco Eduardo
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Campos, Maria Bernadete Silva de
;
https://lattes.cnpq.br/5024245659105477
;
https://lattes.cnpq.br/1808199150615064
The objective of the present research was to study the practical viability of Bacillus subtilis (ACB-69) to control Colletotrichum acutatum, the casual agent of postbloom fruit drop (PFD) under field conditions. First, the bacteria was tested in two different concentrations, one at 5% and the other at 10 %, in the experiment conducted on Pera Sweet orange plants grafted on cravo lemon trees (11 years of planting), in a private property located in Botucatu, São Paulo State, Brazil during the 2007/2008 season. The same treatments were repeated in the following season, however, with or without adding a carbon source (molasses at 5%), on Valencia orange plants grafted on Rangpur lime trees (15 years old). Additional studies were also carried out under the same conditions, aiming to determine the most appropriate growth stages of flowers to apply the biocontrol agent, for the best disease control. For all experiments, the biological products were applied with an air assisted sprayer with the additional intent of evaluating its practicality. It was verified that the weekly application of B. subtilis at 5% reduced the quantity of symptomatic flowers by 47%, while the chemical treatment only showed an18% efficiency when compared to the control. On the other hand, weekly applications of B. subtilis (at 10%) or with one week before the application of the other biological treatments caused a greater average number of effective fruits (ANEF). The addition of a carbon source at the moment of application may favor the antagonism of the bacteria; however, the addition is optional, particularly when its ANEF is evaluated. The best moment to apply the ACB-69 isolate to control PFD was in the open flower stage, when the percentage of symptomatic flowers was evaluated, however, when the bacteria is applied during all flowering stages there is a greater quantity of effective fruits per plant. The use of the air assisted sprayer was considered efficient for the antagonistic application, allowing a better distribution of the inoculum on the plant without damaging the bacterial cells, hence, enabling it to be an indication for future microorganism applications to control diseases.
Análise de duas propostas para a reabilitação da marcha em indivíduos portadores de sequelas neurológicas crônicas
(Universidade Federal de São Carlos, 2010-05-10)
Santos, Fernanda Romaguera Pereira dos
;
Mattioli, Rosana
This work is composed of three distinct studies. In the first one, we compared the muscle coactivation of tibialis anterior (TA) and gastrocunemius medialis (GM) during quiet stance and the also during the stance phase of gait in hemiparetic subjects (hemiparetic group, HG, n=12) and in subjects with no neurologic injuries (control group, CG, n=10). We evaluated the TA and GM electromyographic signal and calculated their overlapping ratio (OR). We concluded that these individuals do not present significant coactivation alterations in the stance phase of gait, but in quiet stance they seem to use the coactivation of the non-paretic limb to maintain postural stability. In the second study we investigated the effects of the association of treadmill training with body weight support (TTBWS) associated with strength training of ankle muscles on the motor control in chronic hemiparetic subjects. Fifteen volunteers were distributed into 2 treatment groups: 1) TTBWS (G1; n=7); and 2) TTBWS associated with resistance training for dorsi and plantar flexors (G2; n=8). We evaluated muscle performance of plantar flexion and dorsiflexion in an isokinetic dynamometer through peak torque (PT), total work (TW) and acceleration time (AT) at the speeds of 60°/s and 120°/s. For gait analysis we assessed the ground reaction forces (GRF). There was an increase in PT and TT of plantar flexion at 60°/s in the paretic side, and an increase in the positive peak of the anterior-posterior GRF component in both sides of G2. We suggested that the proposed intervention leads to improvements in the components related to propulsion of gait. In the third study, we evaluated the effect of the robot assisted gait training (RAGT) in children with spastic diplegia. Twenty children (12 male, 5-13 years old) were evaluated for functional outcomes and spatial-temporal patterns of gait before, after and 3 months after the end of the intervention. Comparisons revealed significant improvements on functional outcomes and in gait mechanics. We concluded that RAGT promotes better gait patterns, and that the learning of this new task is retained even after the end of the intervention.
Estudo da interação de íons cobre e cromo com eletrodos de pasta de carbono modificada e polianilina em meio aquoso por técnica de voltametria de pulso diferencial
(Universidade Federal de São Carlos, 2010-05-11)
Lima, Rodrigo Maracajá Vaz de
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Mattoso, Luiz Henrique Capparelli
;
https://lattes.cnpq.br/5839043594908917
;
https://lattes.cnpq.br/6763854791712123
The electrochemical sensors to measure metallic ions in water and waste water are among the most important areas of research nowadays. The environmental control and monitoring chalenges that stimulated the aim of this work are tanification for industrial leather finishing and cuprous and cupric organic and inorganic fungicides. The features for characterization of metallic ions in water, specially for Cu2+ e Cr6+ and the properties of Humic Acid extracted from Turfe, or Turf Humic Acid (AHT) and Lignossufonic Acid, or Sulfonated Lignin (LigS), were exposed, as well as the properties and synthesis methods for Polyaniline (PAni). The following electrodes were prepaired and used on this work: The carbon paste modified electrodes, prepared with AHT extracted at Mogi river estuarine region near Luis Antonio city São Paulo State, Brazil. Another carbon paste was prepared for comparison with LigS obtained from pinus pulp processing and treatment by Melbar Company (Parana State, Brazil). The working electrode that used PAni films were prepared by electrochemical synthesis onto graphite rods. The cyclic voltammetry technique was used to synthesize PAni in acid media of 0.5 to 1.0 mol L-1 H2SO4 (PAni-H2SO4) and scanning speed of v=20mVs-1, v=50mVs-1. The same procedure was used to synthesize the PAni films, in the same acid media, and the solution has 0.05 mg L-1 of dispersed LigS (PAni-H2SO4+LigS). These electrodes had their Differential Pulse Voltammetry (DPV) current peak response studied with Factorial Planning. The most important results were compared by linear response, sensibility, limit of detection (LD) and repetability. The best electrodes for Cr6+ ions was PAni-H2SO4+LigS with a sensibility of 10.3A/10-7molL-1, 2.87% of repeatability, 5.6% of reproducibility and LD = 1.96 10-8 mol L-1. For copper ions the Carbon Paste modified with LigS was the best electrode wich has a sensibility of 9.5 A/10-7mol L-1, 1.5% of repeatability, reproducibility of 3.5% and LD = 4.9 10-8 mol L-1. Both electrodes have, each other, a linear calibration curve for Ip response that includes the limits of concentration for brazilian s environmental laws (CONAMA 397/april 2008), by DPV method, obtained on acetate buffer, pH=4,5, pulse height zE=75 mV, Ed = -0.35 V and scanning speed v= 20mVs-1.
Formalização de um modelo de processo de reengenharia centrado no usuário para conversão de aplicações desktop em RIAs
(Universidade Federal de São Carlos, 2010-05-12)
Buzatto, David
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Silva, Junia Coutinho Anacleto
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https://lattes.cnpq.br/6200743168568684
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https://lattes.cnpq.br/7916716785143122
The software reengineering becomes important because of the need that organizations have in adjusting to new trends, technologies and user requirements. The term organization should be understood like universities or companies that develop software for use by a large number of people. Thinking about the adequacy of users requirements, is presented in this work the reengineering process of a software called Cognitor, which is a tool designed to support teachers in the process of creating electronic teaching materials. The need to reengineer Cognitor was perceived through a case study where several changes were pointed by users. Some of these changes are: text editor improvement, preview of the images that are inserted in the content pages, feedback to the users, among others. During the reengineering of this software, it was formalized a software reengineering process model, user-centered, for the conversion of desktop applications in RIAs (Rich Internet Application), called UC-RIA (User Centered Rich Internet Application). The process model was named as UC-RIA due to the participation of the potential users during the application s reengineering process, because they were involved in prototyping and in validation of the graphical interfaces of the new version. The results of this study show the capability of the proposed software reengineering model to be used as a support in organizations for the reengineering of their software, mainly because it inserts the users in the reengineering process during the application s Prototyping phase, bringing software to users real needs.
Efeitos de um programa de treinamento de força sobre variáveis da composição corporal, concentrações plasmáticas de leptina e resistina e qualidade de vida em mulheres pós-menopáusicas
(Universidade Federal de São Carlos, 2010-05-14)
Botero, João Paulo
;
Perez, Sergio Eduardo de Andrade
;
https://lattes.cnpq.br/9408953831211309
;
https://lattes.cnpq.br/5429159170761764
Objective: To determine the effect of a resistance training program on body composition andplasmatic concentrations of leptin and resistin in pos-menopausal women.Methods: Twenty-three post-menopausal women (mean age = 56.52 ± 4.42 years) were submitted to12 months of resistance training, twice a week. The training program was performed in 3 sets of 8-10RMs maximal repetitions with an intensity of 75-85% of 1RM. Body composition (DXA), musclestrength (bench press, leg press 45º, arm curl), plasmatic concentration of resistin and leptin wereassessed before and after the training program. Paired Student s t test was used for Bodycomposition, muscle strength and plasmatic concentration of resistin and leptin and non-parametricWilcoxon test for variables of quality of life. Significance level was set at 5%.Results: After the resistance training program, there was a significant increase in muscle strengthand lean mass, and a significant reduction in body weight, fat percentage, fat mass, andconcentrations of leptin and resistin with consequent improvement in quality of life.Conclusions: the interpretation of the results shows that resistance exercise can have significanthealth benefits and quality of life and reduce the concentrations of Leptin and Resistin induced byaging in postmenopausal women.
Aplicação das técnicas espectroscópicas e quimiométricas no estudo do controle de qualidade das drogas vegetais: embaúba, malva e ginseng brasileiro
(Universidade Federal de São Carlos, 2010-05-14)
Leão, Katyúscya Veloso
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Ferreira, Antonio Gilberto
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https://lattes.cnpq.br/3676462220401452
;
https://lattes.cnpq.br/1584302888502091
In the last few years the phytotherapy has emerged as a drug form well accepted and accessible, causing the increase in demand for drugs based on plants throughout the world, becoming an attraction for the pharmaceutical industry. Therefore the investment in quality control have become of extreme importance to ensure safety and efficacy of products. Among many herbal drugs available on the market, this study evaluated commercial samples of embaúba, Brazilian ginseng and mallow, using NMR spectroscopic techniques, 1H NMR in solution, HRMAS 1H and IR allied to chemometric methods. For commercial samples of embaúba, observed by chemometric analysis of data obtained by 1H NMR in solution and IR, most commercial samples were grouped with the species Cecropia glaziovii. By 1H NMR in solution and 2D experiments and comparisons with literature data, it was possible the identification of α-glucose e β-glucose, β-frutofuranose and β-frutopyranose, valine, alanine, threonina, 4-aminobutanoic acid, glutamine and caffeoylquinic acid. For commercial samples of Brazilian ginseng, analyzed by the three techniques, it was observed that most commercial samples were grouped with the species Pfaffia glomerata and by 1H NMR in solution it was possible to identify valine, alanine, threonine and 4-aminobutanoic acid and the sugars: sucrose, α-glucose e α-glucose. For commercial samples of mallow two adulterated samples were detected and grouping of most commercial samples with specie Sida cordifolia. By NMR in solution it was possible to identify valine, threonine, alanine, sucrose, α-glucose and β-glucose, 4-aminobutanoic acid and the ephedrine compound in the aqueous extract of specie Sida cordifofia and in aqueous extract the of specie Malva silvestris valine, threonine, alanine and the malvone A compound were identified. It was found that NMR techniques combined with chemometrics where more efficient than infrared, demonstrating a great potential for quality control, enabling the evaluation of the chemical profile of a extract vegetable as a whole and highlighting the compounds with a greater contribution to the discrimination of species and the indication of a chemical marker.
Propriedades inter e intragranulares de amostras mesoscópicas de YBa2Cu3O7-δ ; preparadas por síntese química
(Universidade Federal de São Carlos, 2010-05-14)
Deimling, Cesar Vanderlei
;
Ortiz, Wilson Aires
;
https://lattes.cnpq.br/0241177338066307
;
https://lattes.cnpq.br/3543120613457891
This work consists of a systematic study of the evolution of the morphological characteristics and the superconducting properties of YBCO samples prepared using the Modified Polymeric Precursors Method (MPPM). Aiming at producing YBCO powder exhibiting the smallest possible intergranular contribution, we have studied, through scanning micrographs, x-ray difractograms and magnetic measurements; the effects of milling, ultrasonic treatments and the pelletizing pressure; the influence of the chelating agents citric acid, tartaric acid ethylenediaminetetraacetic acid; as well as the calcinating temperature, on the morphology and the superconducting properties of this class of samples. From this studies we could conclude that the powder presents mesoscopic granulometry, being formed by aggregates, very difficult to dismantle without insertion a large amount of defects. AC-susceptibility measurements as a function of temperature were used to monitor the evolution of the line, Hc wl(T), which in a field versus temperature magnetic phase diagram, H x T, delineates the region above which the intergranular critical current density of the sample vanishes. Studying the effects of calcinating temperatures below 900°C, we have verified the possibility of monitoring the intergranular characteristics of powder YBCO samples. Above this temperature, the aggregates coalesce in such a way that the intergranular magnetic response is totally suppressed. In order to produce samples exhibiting a narrow intergranular critical current distribution, we have adopted the preparation route involving the chelating agent citric acid since, among all studied samples, those prepared using this route gave the best intergranular contribution to the magnetic response. Due to the mesoscopic granulometry and the high coalescence presented by those powders, sintering under temperatures in the interval from 920°C to 980°C resulted in pellets with the largest degree of inhomogeneity associated with the magnetic response, so that the line Hc wl(T) was impossible to determine. Preparing pellets pressed under 1500 kgf/cm2, 3000 kgf/cm2, 6000 kgf/cm2 and sintered in temperatures ranging from 870°C to 900°C, we could observe several kinds of singular behavior, such as a double superconducting transition, the Paramagnetic Meissner effect (PME) and the occurrence of two minima in magnetization versus magnetic field curves, M x H. Such effects are related with the intergranular properties, being more evident in superconducting granular samples presenting a narrow intergranular critical current distribution. Due to the narrow intergranular critical current distribution, which is a consequence of similar properties of the weak links (WLs), it became possible to build a phase diagram containing the Hc wl(T) line for such samples, including also Hc1(T), which separates the Meissner from the Mixed states. Both lines are extrinsic properties of the samples, since they depend on specific procedures adopted during sample preparation. Associating Hc wl(T) with the upper limit of superconductivity for the intergranular matrix, and Hc1(T) with the frontier of the Meissner state, we have verified two major classes of WLs were present. We were then able to model those boundary lines as if they were type II superconductors. The Ginzburg-Landau parameters obtained from this modeling process are: _0 wl = 19,7 for the WL class having Tc wl = 85,5 K and _1 wl = 238,2 for the class presenting Tc wl = 51,4 K. Simulations of ac-susceptibility measurements as a function of the excitation field, _ac x T, were in good agreement with the experimental results for the powder samples, revealing that such specimens have broad intergranular critical current distributions. For pellets sintered in the 870°C - 900°C temperature interval, simulations of _ac x T are inefficient, since they do not take into account the positive component of the magnetic moment associated to flux trapped at intergranular regions of samples exhibiting PME.
Fracionamento de Ba, Cr, Cu, Ni e Zn em solos tratados com lodo de esgoto em experimentos de longa duração
(Universidade Federal de São Carlos, 2010-05-14)
Santos, Larissa Macedo dos
;
Nogueira, Ana Rita de Araújo
;
https://lattes.cnpq.br/7034773971317045
;
https://lattes.cnpq.br/9439814411927273
As the agronomic importance of the provision of agricultural sewage sludge, and its growing concerning environmental point of view, in this work decomposition procedures of soil samples subjected to the addition of sewage sludge were evaluated for total content determination of Ba, Cd, Cr, Cu, Ni, Pb and Zn; the contents of the aforementioned elements present in two tropical soils, Typic Eutrorthox and Typic Haplorthox, collected through 11 years of experiment were determined and compared, in order to evaluate the accumulation and dynamic of these analytes; the availability of Ba, Cr, Cu, Ni and Zn in the soils subjected to the addition of sewage sludge after 11 consecutive years were evaluated by means of sequential extraction, and a methodology for determining the availability of elements potentially toxic in soils subjected to the addition of sewage sludge from the assessment of humic fractions, fulvic acid 1, fulvic acid 2, humic acid and humin + mineral obtained during the chemical fractionation of soil organic matter was proposed. The use of reversed aqua regia, H2O2, predigestion and agitation after the addition of HF presented above of 90% of recovery for Ba, Cd, Cr, Cu, Ni, Pb and Zn and the complete dissolution of silicate compounds for the tropical evaluated soils. The addition of sludge resulted in significant increase of total contents of Cr, Cu, Ni and Zn to Typic Eutrorthox and Ba, Cu and Zn to Typic Haplorthox. Availability studies presented significant amount of Cr, Cu, Ni and Zn bounded to the Mn and Fe oxides and residual fractions, indicating the low availability of these elements in the evaluated soils. The chemical fractionation of soil organic matter obtained results confirm the high concentration of potentially toxic elements in the oxides in the Typic Eutrorthox soil and in the humic acid in the Typic Haplorthox soil. Although the sewage sludge added to soil increase the levels of potentially toxic elements, these are present in the most stable fractions of soil. In other words, less available or less mobile.
Análise comparativa de fadiga mecânica em compósitos de polipropileno com talco e com nanoargila
(Universidade Federal de São Carlos, 2010-05-17)
Imamura, Rafaela
;
Sousa, José Alexandrino de
;
https://lattes.cnpq.br/7737833809468759
;
https://lattes.cnpq.br/2896005558443593
Talc is a well known lamellar mineral filler much used for mechanical reinforcement of polypropylene (PP) composites. Mineral nanoclay is also a lamellar filler that is gaining much interest due to its reinforcement effect achieved at relatively much reduced filler content. So the main objectives of this work were to establish a comparative study on the mechanical fatigue properties of isotactic PP composites reinforced with both types of fillers: nanocomposites with 2 and 5 wt. % of organophilic nanoclay and microcomposites with 8 and 25 wt.% of ultrafine talc, where the influence of distinct filler particles size and different filler-matrix interfacial interactions were analyzed on the fatigue life and strength properties of these materials with potential engineering applications. All composites were subjected to short-term tensile and Izod impact tests, dynamic-mechanical thermal analysis and microstructural characterization via SEM and TEM, in order to correlate the analyzed characteristics to the fatigue behavior of the materials. The fatigue tests were carried out under stress controlled mode in tensile tension-tension, with a sinusoidal stress input at 1 Hz frequency and R = 0.1. Maleated PP contributed to the enhancement of short-term mechanical properties of talc-filled composites, whilst its influence was much reduced on the same properties of OMMT nanocomposites, due to the modest nanoclay exfoliation achieved in the non-polar PP polymer matrix. In general terms, talc-filled PP microcomposites showed better fatigue performance in comparison to the nanocomposites with O-MMT. However, their Wöhler fatigue S-N curves did not indicate fatigue endurance limits, within the fatigue span of up to 1 x 106 cycles. The main conclusion derived from this study, indicated that when both types of composites exhibited equivalent elastic modulus enhancement, the stronger filler-polymer interfacial interactions present in the talc-filled microcomposites prevailed over the reduced filler particles size of the nanocomposites of O-MMT, however with presence of nanoparticles agglomerates.
Detectando fatores de variedade de codimensão um com propriedades de posição geral
(Universidade Federal de São Carlos, 2010-05-18)
Monteiro, Silvestre da Cruz
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Santos, Edivaldo Lopes dos
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https://lattes.cnpq.br/2167472456497730
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https://lattes.cnpq.br/9781910342368724
This work is an approach to the famous "Product with a Line Problem". It investigates the class of topological spaces whose cartesian product with R is a topological manifold. Such spaces are called "Codimension One Manifold Factors". Based mainly on [5, 7, 14, 15, 24], we introduce the concept of generalized manifolds, which are separable ANR spaces with same local homological behavior that the topological manifolds, we define DAP, DADP, DDP, DHP, DCP general position properties and, through these concepts and a machinery topological-algebraic, we have got answers to the motivator problem. Even about the strategic importance of the DHP general position property, we studied a criterion to detect it into the generalized manifolds category, namely, the P2MP.
Análise da transição do trabalho individual para o trabalho coletivo em cooperativas de reciclagem de resíduos: um estudo de caso da Coopertan de Tangará da Serra-MT
(Universidade Federal de São Carlos, 2010-05-19)
Lima, Ana Maria de
;
Eid, Farid
;
https://lattes.cnpq.br/3456722138811810
The work of separation of recycled materials in the district of Tangará da Serra is a practice that accompanied the birth and development of the city. With passing of the years it is noticed the presence of the interest of the public power and the community in relation to the importance of the reciclagem work developed in the municipal district in the socia aspects, environmental and generation of income. Starting from the need of the construction of the Municipal Sanitary Embankment, the interest with relationship to the workers that made the separation of the domestic garbage, was still individually more evident. In that sense, the general objective of the work was:contribute to building knowledge about the process of transition from individual work to the collective work in the sector of solid waste collection. The specific objectives were: understand the creation and the development of COOPERTAN in the district of Tangará da Serra-MT, analyze the development of the collective work process in COOPERTAN, make a comparative between the individual work and the collective work in the district, understand how the workers of COOPERTAN notice the differences between the individual work and the collective work after the formalization of the cooperative and to identify the strong points and the challenges for the cooperative. The used methodology was the participant research, through accompaniment of the work, meetings, assemblies and the formation of the group in the thematic of cooperatives in selective collection of the domestic garbage and organization of the work. The research demonstrated fragility and difficulty of collective organization and lack of technical formation of the workers. It was also noticed difficulties of the supporting institutions act with coherence, according to the needs and the specificities of the analyzed group. It is worth to point out that, in spite of so many difficulties in that resource, the great majority of those cooperated, mainly the founders that continue in the group, like what they do, they feel pride of the work and they present great expectation and persistence in the search of the autonomy and good results of the enterprise.
Efeitos da exposição à fração solúvel da gasolina em parâmetros bioquímicos e fisiológicos de Prochilodus lineatus
(Universidade Federal de São Carlos, 2010-05-19)
Simonato, Juliana Delatim
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Fernandes, Marisa Narciso
;
https://lattes.cnpq.br/3021357484136942
;
https://lattes.cnpq.br/0889677472146308
The aim of this work was to evaluate the effects of the water-soluble fraction of gasolina (WSFG) to the Neotropical fish Prochilodus lineatus. The WSFG was prepared by adding gasoline to water (1:4) this mixture was then exposed to intense sunlight for 6h, simulating a gasoline spill in tropical conditions. After that the upper insoluble phase was discharged and the WSFG was collected. Fish were exposed for 6, 24 and 96h to the WSFG diluted to 5% (EXP group) or only to water (control group or CTR). The following parameters were analyzed: biochemical (antioxidants and EROD) of gills and liver, hematologic, osmo-ionic, metabolic, endocrine (cortisol) besides the density and distribution of chloride cells (CC) and the activity of gills Na+/K+-ATPase (NKA). The increased in ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST) activity indicated phase I and II biotransformation of the compounds present in the WSFG in both organs. The activation of CYP1A in the gills pointed out the importance of this organ in the biotransformation of xenobiotics. The liver showed an increase in reduced glutathione (GSH) content at 24 and 96 h exposure to WSFG and the increase in the activity of catalase (CAT) and glutathione peroxidase (GPx) after 96 h exposure. The gills showed an activation of the antioxidant defenses with an increased CAT activity soon after 6h exposure and an increase in GSH content after 24h exposure. However, for both organs the antioxidants defense was not enough to prevent oxidative damage, as shown by the occurrence of lipid peroxidation in liver and gills after 6 and 96h of exposure, respectively. The WSFG also promoted hemolysis, as indicated by the changes in the hematological parameters analyzed and an increase in plasma K+. Fish showed a secondary stress response, noted by the occurrence of hyperglycemia in all the periods of exposure, despite no significant increase in plasma cortisol. The WSFG also lead to an increase in the density of CC, in the activity of NKA, in plasma concentrations of Na+ and in the osmolarity in fish exposed to WSFG for 24h. Taken together these results showed that the compounds present in the WSFG interfere on the functioning of vital organs such as liver and gills of Prochilodus lineatus.