184 resultados para COMPRESSED MONOLAYERS


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Pós-graduação em Química - IQ

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Thin films of the bis[2,3,9,10,16,17,23,24-octachlorophthalocyaninate] lutetium(III) complex (LuPc2Cl32) have been prepared by the Langmuir-Blodgett and the Langmuir-Schaefer (LS) techniques. The influence of the chlorine substituents in the structure of the films and in their spectroscopic, electrochemical and sensing properties has been evaluated. The pi-A isotherms exhibit a monolayer stability greater than the observed in the unsubstituted analogue (LuPc2), being easily transferred to solid substrates, also in contrast to LuPc2. The LB and LS films present a linear growth forming stratified layers, monitored by UV-VIS absorption spectroscopy. The latter also revealed the presence of LuPc2Cl32 in the form of monomers and aggregates in both films. The FTIR data showed that the LuPc2Cl32 molecules present a non-preferential arrangement in both films. Monolayers of LB and LS were deposited onto 6 nm Ag island films to record surface-enhanced resonance Raman scattering (SERRS), leading to enhancement factors close to 2 x 10(3). Finally, LB and LS films deposited onto ITO glass have been successfully used as voltammetric sensors for the detection of catechol. The improved electroactivity of the LB and LS films has been confirmed by the reduction of the overpotential of the oxidation of catechol. The enhancement of the electrocatalytic effect observed in LB and LS films is the result of the nanostructured arrangement of the surface which increases the number of active sites. The sensors show a limit of detection in the range of 10(-5) mol/L.

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The energy is considered one of the most important elements in the human´s life providing the survival as well as the well being. Nowadays, the technologies destined to generate power burn fossil fuels which pour gases (carbon dioxide among them) that contribute to the global warming phenomenon. Several research groups and universities have been studying different methods for generating power with low carbon dioxide emissions, including the possibility of burning zero-carbon fuels. In this text, it has been put attention to the Advanced Zero Emission Power Plants (AZEP) which separate the CO2 (from the gases involved in the power generation), compress it, dehydrate it and store it in appropriate reservoirs. The goal of this study was to find a possible solution to produce CO from CO2, activated by solar energy; the reaction between CO and steam generates a syngas comprised of H2 and CO2, which can be separated by chemical and/or physical processes. The text also contains a study concerning the compressed air energy storage power plant (CAES) and come up with its modification to C[CO2]ES. This power plant stores CO2 directing it to a reverse combustion process to produce CO which is headed to a syngas reactor to produce CO2 and H2. Hydrogen is separated and carried to the thermal cycle to generate power with low carbon emissions

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The aim of this study was to verify through microtensile test the influence of time and concentration of surface conditioning with hydrofluoric acid and its interference in the adhesion of dual resin cement to porcelain.We used 32 bodies of glass-ceramic lithium disilicate system IPS e.max Press LT with dimensions of 6mm thick, 8 mm in length and 8 mm in length, which will be molded to obtain composite resin blocks corresponding to blocks ceramics. Ceramic and resin blocks were divided into 16 groups (n = 4) and numbered according to the concentration of hydrofluoric acid (2.5%, 5%, 7.5% and 10%) and conditioning time (20 seconds, 40 seconds, 1 minute and 2 minutes). The blocks were cleaned in ultrasonic apparatus with distilled water and dried with compressed air, subjected to acid etching and air-jet washed with water, dried with compressed air and received application of silane agent Monobond-S, followed by adhesive Excite ( Ivoclar Vivaden). Each ceramic block was bonded to the corresponding block of resin through the resin cement Multilink Automix. The specimens were cut to obtain nine micro samples for each set of ceramic-resin with 1 mm X 1 mm X 12 mm in length, which were submitted to microtensile test. The results were analyzed with descriptive statistics and analysis of variance with significance level of 5%, revealing that there were statistically significant (p = 0.000001 <0.05). From the Tukey test can be concluded that etching with hydrofluoric acid and 2.5% for 120 seconds gave the best bond strength, however, no statistical difference between the conditioning with the same acid in the concentration of 5.0% for 20 to 40 seconds

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This work presents the objective of producing organic fertilizer from the waste generated at FCT/UNESP and its use in the growing sunflower. For this, there were collected wastes of pruning/weeding and organic waste from the canteen. It were made two types of treatments, one conventional and the other mechanized, using three mass ratios: ratio 1 (30% wastes of pruning/weeding (RP) + 70% organic waste (RC)), ratio 2 (50% RP + 50% RC) and ratio 3 (70% RP + 30% RC). The conventional system was done windrow with turning manual and the mechanized system was developed in reactors by injecting compressed air. The compounds produced were analyzed in terms of pH, organic matter, organic carbon, mineral residue, nitrogen, phosphorus and potassium, which could be compared to the values stipulated by the Instrução Normativa n° 25 de 23/07/2009 do Ministério da Agricultura, Pecuária e Abastecimento. The compounds produced were used on growing sunflowers in 14 different conditions for the systems manual and mechanized, totaling 26 treatments with the following proportions... (Complete abstract click electronic access below)

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The main objective is to create a software, using C++ language, for reading and exhibiting in a graphic an Electrocardiogram (ECG) wave. The data is recorded as a FM modulated signal and compressed using Adaptive Differential Pulse Code Modulation (ADPCM). The signal have this characteristics because it was acquired using an experimental equipment, this equipment is the result of research made by the professor who supervised this work. FM demodulation techniques in discrete time, discrete filters and digital signal processing are some of the topics that can be found in this essay. Some concepts about the human heart and about ECG waves are also briefly introduced. These concepts are necessary for understanding the final evaluation of the software performance. The development is partly made using MATLAB. Most of the functions that are used on the software are first tested and designed in MATLAB environment. In the end, an evaluation is done comparing the results that are expected with the ones that MATLAB presents and the ones that the developed software presents

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In this study was shown the historical uses of compressed air by humanity, the general scenario of its uses and the most important steps of a project to set up an industrial network of compressed air, from the selection of a suitable compressor to the design of a distribution network, discussing all the possibilities and their characteristics as well as the feasibility of them. A case study was conducted in a food company where was implemented an industrial compressed air network. Information was collected regarding the consumers points of compressed air, as well as the layout of the new facility, necessary for the development of the distribution system. Two methods were used, analytical and nomogram, which complemented each other to the definition of appropriated tubing, both financially and physically

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The need for development of new materials is a natural process in the companies’ technological point of view, seeking improvements in materials and processes. Specifically, among the materials, ceramic exhibit valuable properties, especially the covalent ceramics which have excellent properties for applications which requires the abrasion resistance, hardness, high temperatures, resistence, etc. being a material that has applications in several areas. Most studies are related to improvement of properties, specially fracture toughness that allows the expansion of its application. Among the most promising ceramic materials are silicon nitride (Si3N4) which has excellent properties. The goal of this work was the development and caracterization of Si3N4-based ceramics, doped with yttrium oxide (Y2O3), rar earth concentrate (CTR2O3) and cerium oxide (CeO2) in the same proportion for the evaluation of properties. The powders' mixtures were homogenized, dried and compressed under pressure uniaxial and isostatic. Sintering was carried out in 1850 ⁰C under pressure of 0,1MPa N2 for 1 h with a heating rate of 25 ⁰C / min and cooling in the furnace inertia. The characterizations were performed using Archimedes principle to relative density, weight loss by measuring before and after sintering, phase analysis by X-ray diffraction, microstructure by scanning electron microscope (SEM), hardness and fracture toughness by the method Vickers indentation. The results obtained showed relative density of 97-98%, Vickers hardness 17 to 19 GPa, fracture toughness 5.6 to 6.8 MPa.m1/2, with phases varying from α-SiAlON and β-Si3N4 depending the types of additives used. The results are promising for tribological applications and can be defined according to the types of additives to be used

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The N-terminus of the human dihydroorotate dehydrogenase (HsDHODH) has been described as important for the enzyme attachment in the inner mitochondrial membrane and possibly to regulate enzymatic activity. In this study, we synthesized the peptide acetyl-GDERFYAEHLMPTLQGLLDPESAHRL AVRFTSLGamide, comprising the residues 33-66 of HsDHODH N-terminal conserved microdomain. Langmuir monolayers and circular dichroism (CD) were employed to investigate the interactions between the peptide and membrane model, as micelles and monolayers of the lipids phosphatidylcholine (PC), 3-phosphatidylethanolamine (PE) and cardiolipin (CL). These lipids represent the major constituents of inner mitochondrial membranes. According to CD data, the peptide adopted a random structure in water, whereas it acquired α-helical structures in the presence of micelles. The π–A isotherms and polarization- modulated infrared reflection-absorption spectroscopy on monolayers showed that the peptide interacted with all lipids, but in different ways. In DPPC monolayers, the peptide penetrated into the hydrophobic region. The strongest initial interaction occurred with DPPE, but the peptide was expelled from this monolayer at high surface pressures. In CL, the peptide could induce a partial dissolution of the monolayer, leading to shorter areas at the monolayer collapse. These results corroborate the literature, where the HsDHODH microdomain is anchored into the inner mitochondrial membrane. Moreover, the existence of distinct conformations and interactions with the different membrane lipids indicates that the access to the enzyme active site may be controlled not only by conformational changes occurring at the microdomain of the protein, but also by some lipid-protein synergetic mechanism, where the HsDHODH peptide would be able to recognize lipid domains in the membrane. - See more at: http://www.eurekaselect.com/122062/article#sthash.1ZZbc7E0.dpuf

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Pós-graduação em Biotecnologia - IQ

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