Influência das espécies do plasma de N2 + O2 nas propriedades físicoquímicas das superfícies do pet

This work reports the influence of the poly (ethylene terephthalate) textile and films surface modification by plasmas of O2 and mixtures (N2 + O2), on their physical and chemical properties. The plasma surface polymeric modification has been used for many researchs, because it does not affect the environment with toxic agents, the alterations remains only at nanometric layers and this technique shows expressive results. Then, due to its good acceptance, the treatment was carried out in a vacuum chamber. Some parameters remained constant during all treatment, such as: Voltage 470 V; Pressure 1,250 Mbar; Current: 0, 10 A and gas flow: 10 cm3/min, using oxygen plasma alternating the treatment time 10 to 60 min with an increase of 10 min to each subsequent treatment. Also, the samples were treated with a gas mixture (nitrogen + oxygen) which was varied only the gas composition from 0 to 100% leaving the treatment time remaining constant to all treatment (10 min). The plasma treatment was characterized in-situ with Optics Emission Spectroscopy (OES), and the samples was characterized by contact angle, surface tension, Through Capillary tests, Raman spectroscopy, Infrared attenuated total reflection (IR-ATR) and atomic force microscopy, scanning electronic Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). The results showed that oxygen treated fabrics presented high wettability, due to the hydrophilic groups incorporation onto the surface formed through spputering of carbon atoms. For the nitrogen atmosphere, there is the a film deposition of amine groups. Treatment with small oxygen concentration in the mixture with nitrogen has a higher spputered species of the samples

Modificação superficial de filmes de poliéster usando plasma a baixa temperatura

A polyester film has a vast application field, due some properties that are inherent of this kind of material such as, good mechanical resistance, chemical resistance to acids and bases and low production cost. However, this material has some limitations as low superficial tension, flat surface, low affinity to dyers, and poor adhesion which impede the use of the same ones for some finality as good wettability. Among the existent techniques to increase the superficial tension, plasma as energy source is the more promising technique, because of their versatility and for not polluting the environment. The plasma surface polymeric modification has been used for many researchers, because it does not affect the environment with toxic agents, the alterations remains only at nanometric layers and this technique shows expressive results. Then, due to its good acceptance, polyester films were treated with oxygen plasma varying the treatment time from 10 to 60 min with an increase of 10 min to each subsequent treatment. Also, the samples were treated with a gas mixture (nitrogen + oxygen) varying the percentage of each gas the mixture from 0 to 100%, the treatment time remaining constant to all treatments (10 min). After plasma treatment the samples were characterized by contact angle, surface tension, Raman spectroscopy, Infrared attenuated total reflection (IR-ATR) and atomic force microscopy, with the aim to study the wettability increase of treated polyester films as its variables. In the (O2/N2) plasma treatment of polyester films can be observed an increase of superficial roughness superior to those treated by O2 plasma. By the other hand, the chemical modification through the implantation of polar groups at the surface is obtained more easily using O2 plasma treatment

Use of near-infrared Raman spectroscopy to detect IgG and IgM antibodies against Toxoplasma gondii in serum samples of domestic cats

Near-infrared Raman spectroscopy (NIRS) is a particularly promising technique that is being used in recent years for many biomedical applications. Optical spectroscopy has gained increasing prominence as a tool for quantitative analysis of biological samples, clinical diagnostic, concentration measurements of blood metabolites and therapeutic drugs, and analysis of the chemical composition of human tissues. Toxoplasmosis is an important zoonosis in public health, and domestic cats are the most important transmitters of the disease. This disease can be detected by several serological tests, which usually have a high cost and require a long time. The goal of this work was to investigate a new method to diagnosis Toxoplasma gondii infections using NIRS. In order to confirm antibody detection, 24 cat blood scrum samples were analyzed by the Raman spectra, from which 23 presented positive serology to toxoplasmosis and one was a reference negative serum. Characteristic Raman peaks allowed differentiation between negative and positive sera, confirming the possibility of antibody detection by Raman spectroscopy. These results give the first evidence that this technique can be useful to quantify antibodies in cat sera.

Modificação superficial do tecido 100% algodão tratado com plasma

The 100% cotton fabric (CO)* treated with plasma of methane CH4 has direct application in all areas that needs of aqueous solutions repellent material like coatings and uniforms applied biomedical, aeronautics, and automobile between others. 100% cotton fabric (CO) samples were treated by plasma with two differents atmosphere: Methane gas (CH4), treatment time was varied in 10 in 10 min. until 60 min., and mixture methane/argon (CH4/Ar), it was varied the proportion 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 e 9:1, with treatment time of 30 minutes. In both, the fluxe was 5 sccm (second cubic centimeter), pressure 6 mbar, voltage 490 V and current 0,15A. The objective of work was measure the superficial tension of 100% CO then it treated with plasma, using contact angle measures of water and glycerol with the surface. The samples were tested after treatment, with 8 and 12 months to verify the superficial modification effects. It was verified an increase of hydrophobility with the Sessile drop values varied between 116,69º to 137,85º and it carried on after 12 months. The no treated samples shows contact angle equal 0º. OES analysis and Raman spectroscopy were accomplished. In the SEM analysis was verified oligomers. The plasma treatment is correct environmental, It turning greater than conventional treatments

Diagnóstico de descarga de cátodo oco de ar e pós-descarga Ar N2 por espectroscopia de emissão óptica e espectrometria de massa

Many applications require that the plasma discharge is produced apart from the surface to be processed, thus preventing damage caused by bombardment and/or plasma radiation. In the post-discharge regime in various applications thermally sensitive materials can be used. In this work, active species produced by discharge and post-discharge hollow cathode were diagnosed by optical emission spectroscopy and mass spectrometry. The discharge was produced with the gases Ar and Ar - N2 gas flow ranging from 1 to 6 cm3/min and electric current between 150 to 600 mA. It was estimated that the ion density inside the hollow cathode, with 2 mm diameter ranged between 7.71 and 14.1 x 1015 cm-3. It was observed that the gas flow and the electric current changes the emission intensity of Ar and N2 species. The major ionic species detected by quadrupole mass spectrometry were Ar+ and N2+. The ratio of optical emission intensities of N2(1 +)/Ar(811 nm) was related to the partial pressure of N2 after the hollow cathode discharge at low pressure

Monitoramento em tempo real de processos fermentativos por espectroscopia no infravermelho próximo (NIRS)

A chemical process optimization and control is strongly correlated with the quantity of information can be obtained from the system. In biotechnological processes, where the transforming agent is a cell, many variables can interfere in the process, leading to changes in the microorganism metabolism and affecting the quantity and quality of final product. Therefore, the continuously monitoring of the variables that interfere in the bioprocess, is crucial to be able to act on certain variables of the system, keeping it under desirable operational conditions and control. In general, during a fermentation process, the analysis of important parameters such as substrate, product and cells concentration, is done off-line, requiring sampling, pretreatment and analytical procedures. Therefore, this steps require a significant run time and the use of high purity chemical reagents to be done. In order to implement a real time monitoring system for a benchtop bioreactor, these study was conducted in two steps: (i) The development of a software that presents a communication interface between bioreactor and computer based on data acquisition and process variables data recording, that are pH, temperature, dissolved oxygen, level, foam level, agitation frequency and the input setpoints of the operational parameters of the bioreactor control unit; (ii) The development of an analytical method using near-infrared spectroscopy (NIRS) in order to enable substrate, products and cells concentration monitoring during a fermentation process for ethanol production using the yeast Saccharomyces cerevisiae. Three fermentation runs were conducted (F1, F2 and F3) that were monitored by NIRS and subsequent sampling for analytical characterization. The data obtained were used for calibration and validation, where pre-treatments combined or not with smoothing filters were applied to spectrum data. The most satisfactory results were obtained when the calibration models were constructed from real samples of culture medium removed from the fermentation assays F1, F2 and F3, showing that the analytical method based on NIRS can be used as a fast and effective method to quantify cells, substrate and products concentration what enables the implementation of insitu real time monitoring of fermentation processes

Surface-enhanced Raman scattering and micro-Raman imaging of Langmuir-Blodgett films of rhodium phthalocyanine

Rhodium phthalocyanine (RhPc) was synthesized and ultra thin Langmuir-Blodgett (LB) films of RhPc were successfully fabricated. The LB film characterization was carried out using both UV-vis absorption spectra and Raman scattering. The Raman spectroscopy was carried out using 633 and 780 nm laser lines. LB films were deposited onto Ag nanoparticles to achieve the surface-enhanced pre-resonance Raman scattering (pre-SERRS) and surface-enhanced Raman scattering (SERS) for both laser lines, respectively, which allowed the characterization of the RhPc ultra thin films. The morphology of the LB RhPc neat film is extracted from micro-Raman imaging. (C) 2003 Elsevier B.V. All rights reserved.

Surface-enhanced resonance Raman scattering: Single-molecule detection in a Langmuir-Blodgett monolayer

Surface-enhanced resonance Raman scattering (SERRS) is used for single-molecule detection from spatially resolved 1-mum(2) sections of a Langmuir-Blodgett (LB) monolayer deposited onto a Ag film. The target molecule, his (benzimidazo) thioperylene (BZP), is dispersed in an arachidic acid monomolecular layer containing one BZP molecule per mum(2) which is also the probing area of the Raman microscope. For concentrated samples (attomole quantities in the field of view), average SERRS, surface-enhanced fluorescence (SEF), and Raman imaging, including line mapping and global images at different temperatures, were recorded. Single-molecule SERRS spectra, obtained using an LB monolayer, present changes in bandwidth and relative intensities, highlighting the properties of single-molecule SERRS that are lost in average SERRS measurements of mixed LB monolayers obtained at the same temperatures. Also, the dilute system phenomenon of blinking is discussed with regard to results obtained from LB monolayers. The dilution process used in the single-molecule LB SERRS work is independently supported by fluorescence results obtained from very dilute solutions with monomer concentrations down to 10(-12) M.

Incorporation of Ag nanoparticles into membrane mimetic systems composed by phospholipid layer-by-layer (LbL) films to achieve surface-enhanced Raman scattering as a tool in drug interaction studies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Micro-Raman spectroscopy and SEM/EDX applied to improve the zircon fission track method used for dating geological formations

The zircon mineral is widely studied in geochronology. In the case of the fission track method (FTM), the age is determined by the density of fission tracks at the zircon surface, which can be observed with an optical microscope after an appropriate chemical treatment (etching). The etching must be isotropic at the zircon grain surface to be used in the FTM, which leads those zircon grains whose etching is anisotropic to be discarded. The only reason for this discarding is the nonuniform morphology of the surface grain seen by optical microscopy, that is, no further physicochemical analysis is performed. In this work, combining micro-Raman and scanning electron microscopy (SEM) to study the etching anisotropy, it was shown that zircon grains that present at least one area at the surface where the density of fission track is uniform can be used in the FTM. The micro-Raman showed characteristic spectra of the standard zircon sample either from the areas where there are tracks or from where there are not. The only difference found was in the Raman bandwidths, which were broader for the areas with higher density of fission tracks. This suggests simply a decrease in the relative percentage of the crystalline/amorphous phases at these areas. The SEM/energy dispersive spectrometry (EDX) showed that there were no significant differences in the principal chemical composition at the areas with and without fission tracks. Copyright (c) 2008 John Wiley & Sons, Ltd.

Coupling Surface-Enhanced Resonance Raman Scattering and Electronic Tongue as Characterization Tools to Investigate Biological Membrane Mimetic Systems

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Surface-enhanced raman scattering: metal nanostructures coated with langmuir-blodgett films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo de coprólito da bacia sedimentar do Araripe por meios de espectroscopia FT-IR e difração de Raios-X

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Deposição de A/N por sputtering não reativo

In this work we deposit via non-reactive magnetron sputtering of radio-frequency nanofilmes of nitreto of aluminum(AlN). The nanofilms aluminum nitride are semiconductors materials with high thermal conductivity, high melting point, piezoelectricity and wide band gap (6, 2 eV) with hexagonal wurtzite crystal structure, belonging to the group of new materials called III-V nitrides in which together with the gallium nitride and indium nitride have attracted much interest because they have physical and chemical properties relevant to new technological applications, mainly in microelectronic and optoelectronic devices. Three groups were deposited with thicknesses nanofilms time dependent on two substrates (glass and silicon) at a temperature of 25 ° C. The nanofilms AlN were characterized using three techniques, X-ray diffraction, Raman spectroscopy and atomic force microscopy (AFM), examined the morphology of these. Through the analysis of X-rays get the thickness of each sample with its corresponding deposition rate. The analysis of X-rays also revealed that nanofilms are not crystalline, showing the amorphous character of the samples. The results obtained by the technique, atomic force microscopy (AFM) agree with those obtained using the technique of X-rays. Characterization by Raman spectroscopy revealed the existence of active modes characteristic of AlN in the samples

Investigation in SrTiO3-CaTiO3-PbTiO3 ternary thin films by dielectric proprieties and Raman spectroscopy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)