Showing papers by "National Nuclear Energy Commission published in 2003"
TL;DR: Applications in protein processing are described and variations of immobilized metal ion affinity chromatography are described as well as other metal affinity-based technologies.
445 citations
TL;DR: In this article, an avaliacao in vitro da biocompatibilidade de diferentes tipos de biomateriais foi realizada pelo teste de citotoxicidade em cultivo de celulas de tecido conectivo de camundongos, NCTC Clone 929 da American Type Culture Collection.
Abstract: A avaliacao in vitro da biocompatibilidade de diferentes tipos de biomateriais foi realizada pelo teste de citotoxicidade em cultivo de celulas de tecido conectivo de camundongos, NCTC Clone 929 da American Type Culture Collection. O estudo comparativo do ensaio de citotoxicidade foi realizado com duas metodologias: 1) ensaio de difusao em agar e 2) ensaio de incorporacao do vermelho neutro. Os resultados obtidos demonstraram que ambas as metodologias podem ser utilizadas, de acordo com o tipo de amostra a ser analisada.
145 citations
TL;DR: In this article, the analysis of poly(N-vinyl-2-pyrrolidone) (PVP) submitted to direct photocrosslinking in aqueous solution, using low pressure Hg lamp (lem ¼ 254 nm).
140 citations
TL;DR: Mercury speciation in phosphorus powder matrices and soda lime glass waste from new and spent fluorescent lamp wastes has been studied by thermo-desorption/atomic absorption spectrometry (TDAAS), X-ray diffraction (XRD), cold vapor-atomic absorption (CV-AAS) and atomic emission spectrometer/inductively coupled plasma (ICP/AES).
121 citations
TL;DR: A survey of radon gas concentration in dwellings in Rio de Janeiro city, Brazil, in urban area with nearly 7 million inhabitants, through integrated sampling methods, using a Solid State Nuclear Track Detectors Technique (SSNTD).
89 citations
TL;DR: In this article, a FTIR Spectrometer was used to identify the chemical origin of all the bands present in the infrared region to study the chemical and thermal action on the hard dental tissues.
Abstract: The chemical components present in the hard tissue such as water, phosphate, carbonate and organic material strongly absorb infrared radiation. The research in dentistry area has a fundamental interest in identifying the chemical origin of all the bands present in the infrared region to study the chemical and thermal action on the hard dental tissues. To improve this technique it is important to identify chemical alterations in the tissues and characterize their properties in a more natural form. Transmission and reflection spectra in the infrared range from 2.5 µm to 25 µm of the enamel and dentin tissues from human and bovine teeth were acquired. Sliced samples were used for the transmission spectra, polished blocks and natural surfaces for the reflection spectra. Tissue spectra were registered between 4000 and 400 cm−1 in a FTIR Spectrometer. No differences were found between the mineral matrix of human and bovine tissues, only differences in intensity among bands were observed. Regarding the ...
87 citations
TL;DR: Results indicate that 6 h activation at 40-42 degrees C, starting with an OD (A(600) of approximately 3 in a very rich medium, were conditions capable of providing the maximum secretion level for a vector utilizing the DsbA signal sequence and E.coli W3110 or RB791 as host cells.
Abstract: The influence of different factors acting on Escherichia coli periplasmic expression of recombinant human growth hormone (hGH) in shake flask cultures has been investigated. Bacterial vectors containing the phage lambdaP(L) promoter, which is temperature activated, were utilized. Four different signal peptides were compared: DsbA, npr, STII and one derived from the natural hGH signal peptide, this last used as a reference. Other factors such as medium composition, optimized induction and expression conditions, and different bacterial strains were also studied. The determination of hGH, carried out directly in osmotic shock fluids, was based on an isocratic reversed-phase high-performance liquid chromatography method, which allows direct, rapid evaluation of the quality and quantity of hGH being secreted in the bacterial periplasmic space immediately after or even during fermentation. The level of hGH production increased 2.5-fold compared with the reference vector, reaching a level of 3.9 +/- 0.63 micro g/ml/A(600) (n = 6; coefficient of variation = 16.2%). The expression level was affected by the signal peptide and by the induction conditions, being more effective when activation started in the early logarithmic phase which, however, exhibited remarkably different optical density (OD) according to medium composition. Our results thus indicate that 6 h activation at 40-42 degrees C, starting with an OD (A(600)) of approximately 3 in a very rich medium, were conditions capable of providing the maximum secretion level for a vector utilizing the DsbA signal sequence and E.coli W3110 or RB791 as host cells.
70 citations
01 Jan 2003
TL;DR: Qualitative and quantitative polymerase-chain-reaction-based methods to detect genetically modified soy and maize and maize were applied to processed foods sold commercially in Brazil in 2000 and again in 2001.
Abstract: Qualitative and quantitative polymerase-chain-reaction-based methods to detect genetically modified (gm) soy (RoundupReadyTM soy) and maize (Bt176 Maximizer maize; Bt11 maize, MON810 Yield Gard corn, T25 LibertyR Link maize) were applied to processed foods sold commercially in Brazil. In total 100 foods containing maize and 100 foods containing soy were analysed in 2000 and again in 2001. In 2000, 13% of the soy containing products and 8% of those containing maize were shown to consist of material derived from the corresponding genetically modified organisms. In five samples of the products containing gm soy 4% of the soy derived material was identified as coming from gm soybeans, whereas in the case of products containing gm maize five samples of the maize derived material were found to contain 4% of gm maize. In 2001, gm soy was found in 21% of the soy containing foods, and gm maize was found in 9% of the maize containing products. Eight samples of the products containing gm soy were shown to contain 4% of gm soy, the corresponding values for gm maize were five samples 4%.
56 citations
TL;DR: The uranium concentration in Brazilian phosphate fertilizers ranging from 5.17 to 54.3 ppm is in good agreement with the results reported in the literature for similar fertilizers produced in other countries.
54 citations
19 Oct 2003
TL;DR: In this article, a commercial TlBr powder was used for growing crystals for detector applications, and this material was purified by the zone refining technique using inductively coupled plasma mass spectroscopy (ICP-MS).
Abstract: Thallium bromide (TlBr) is a semiconductor compound with a high atomic number and a wide bandgap, being a very promising material to be used as room temperature radiation detectors. In this work, commercial TlBr powder was used for growing crystals for detector applications. To reduce impurities, this material was purified by the zone refining technique. Trace impurities at ppb/ppm level were analyzed using inductively coupled plasma mass spectroscopy (ICP-MS). The efficiency of the purification was evaluated through studies of the decrease impurities concentrations in the TlBr powder and in the purified materials. The crystal quality was verified by X-ray diffraction (XRD). To evaluate the crystal as a semiconductor detector, systematic measurements of the transmittance, resistivity, and the radiation response (/sup 241/Am, /sup 57/Co, /sup 125/I, and /sup 133/Ba) gamma rays were carried out.
50 citations
TL;DR: In this article, experimental results for indium adsorption onto some ion exchange resins of different organic functional groups are presented, and the experimental results allowed to select the chelating resin containing iminodiacetic acid groups with high potential for purification of the indium sulfate solution.
TL;DR: In this paper, a new lead fluoroborate glass doped with different concentrations of Nd 2 O 3 varying from 0.04 up to 3.49% was presented for the 4 F 3/2 → 4 I 11/2 transition.
TL;DR: A tentative of retrospective dosimetry was performed, indicating that the method is feasible only for low level exposure (below 0.5Gy), while for higher doses there is a need to apply appropriate correction factors, which take into consideration mainly the persistence of chromosomal translocations along with time.
Abstract: Fluorescence in situ hybridization (FISH) is a powerful method largely used for detecting chromosomal rearrangements, translocations in particular, which are important biomarkers for dose assessment in case of human exposure to ionizing radiation. To test the possibility of using the translocation analysis by FISH-painting method in retrospective dose assessment, we carried out in vitro experiments in irradiated human lymphocytes, in parallel with the analysis of translocations in lymphocytes from 10 individuals, who were exposed to 137 cesium in the Goiânia (Brazil) accident (samples collected 10 years after exposure). The in vitro dose–response curve for the genomic translocation frequencies (FGs) fits a linear quadratic model, according to the equation: Y =0.0243 X 2 +0.0556 X . The FG values were also calculated for the individuals exposed to 137 cesium , ranging from 0.58 to 5.91 per 100 cells, and the doses were estimated and compared with the results obtained by dicentric analysis soon after the accident, taking the opportunity to test the validity of translocation analysis in retrospective biodosimetry. A tentative of retrospective dosimetry was performed, indicating that the method is feasible only for low level exposure (below 0.5 Gy), while for higher doses there is a need to apply appropriate correction factors, which take into consideration mainly the persistence of chromosomal translocations along with time, and the influence of endogenous and exogenous factors determining the inter-individual variability in the cellular responses to radiation.
TL;DR: In this paper, the liquid-phase hydrogenation of benzene to cyclohexene was studied using a Ru/SiO2 catalyst prepared by reduction of ruthenium(III) chloride impregnated in a hydrophilic nonporous silica.
TL;DR: This work investigates the application of seasonal constraints for the set of the Emergency Diesel Generation of a typical four-loop pressurized water reactor in order to planning and optimizing its surveillance test policy.
TL;DR: PtRu/C electrocatalysts were prepared by impregnation of the complex (η-C 2 H 4 )(Cl)Pt(μCl) 2 Ru(Cl)(η 3,η3 -C 10 H 16 ) on to a carbon support as mentioned in this paper.
TL;DR: This review article describes and analyzes the main synthetic and purification strategies that have been used for the production of recombinant human growth hormone, prolactin, thyrotropin, luteinizing hormone and follicle-stimulating hormone, giving special consideration to the few published downstream processes utilized by the biotechnology industry.
TL;DR: In this article, spectroscopic properties for laser action at 1532nm were observed for the sample with 0.1% of Er2O3: fluorescence lifetime of 3.76m, emission cross-section of 0.69×10−20 cm2 and effective line width of 68.7nm.
TL;DR: The results suggest that increase in skin vascular permeability by crotalic PLA(2)s is mediated by activation of sensory C-fibers culminating in the release of substance P, as well as byactivation of mast cells which in turn release amines such as histamine and serotonin.
TL;DR: In this article, the laser potential of three different glass families doped with Yb3+: alkali lead fluorborate (PbO), heavy metal oxide (Bi2O3), and niobium tellurite (TeO2-Nb2O5-K2O-Li2O).
TL;DR: The novel methodology was applied to the study of the best cultivation conditions and was able to detect a significant difference in retention time (t(R)) between pituitary and recombinant hTSH, probably reflecting the influence of the heterogeneity of the carbohydrate moiety on the hydrophobic properties of the molecule.
TL;DR: In this article, a study about the sorption of copper-diethyldithiocarbamate complex onto polyurethane foam (PUF) was conducted, which revealed that a film diffusion process was a rate-determining mechanism.
Abstract: This paper presents a study about the sorption of copper-diethyldithiocarbamate complex onto polyurethane foam (PUF). It was observed that the maximum sorption of Cu(II) (80 or 150 µg L-1) was verified at pH 6.8 in presence of 4.5 x 10-5 mol L-1 DDTC. The shaking time needed to achieve the equilibrium was 40 minutes. From these data, a kinetic characterization was performed by applying three models, which revealed that a film diffusion process was a rate-determining mechanism. Results also indicated that a ether-like solvent extraction was the sorption mechanism. The investigation of many metallic ions as concomitants showed that the sorption by foam is relatively selective and it can be enhanced by using a suitable masking agent or incrementing the foam mass.
TL;DR: In this article, the authors present the characteristics of carbonized rice husk powders and pellets as well as the SiO 2 /C mass relation contained in these materials and evaluate the influence of parameters such as chlorination catalysts, bed height and chlorine gas concentration.
01 Aug 2003-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, the sensitized radiation vulcanization of natural rubber latex has been carried out with 250 keV electrons with the presence of sensitizers like the n-butyl acrylate (n-BA).
Abstract: The sensitized radiation vulcanization of natural rubber latex has been carried out with 250 keV electrons. Latex was irradiated over a range of the beam current from 5 to 20 mA in the presence of sensitizers like the n-butyl acrylate (n-BA). The vulcanization dose decreases with increasing beam current condition. The rate of vulcanization (Rvul) depends on the beam current (I) as given by the equation Rvul=kI0.6.
TL;DR: In this article, the k 0 instrumental neutron activation analysis has been applied at Radiochemical Laboratory, CDTN/CNEN, Brazil, by means of TRIGA MARK I IPR-R1 research reactor.
Abstract: Since 1995 the k 0 instrumental neutron activation analysis has been applied at Radiochemical Laboratory, CDTN/CNEN, Brazil, by means of TRIGA MARK I IPR-R1 research reactor. At that time , f, and T n were determined and the most recent determination of these parameters confirmed the great stability of the reactor along these years. In order to verify the efficiency and accuracy of the method, several certified reference materials have been systematically analyzed. Participating in Intercomparison Exercises organized by IAEA has been an important, essential and useful procedure to quality control. CDTN is the only Brazilian Institute to apply the k 0-INAA to determine elements by means of their isotopes through short, medium and long half life using its own nuclear reactor.
TL;DR: A discussion concerning hand areas near the thumb and forefinger as being more suitable for GSR collection as well as a comparison between differences observed using 2% diluted EDTA, proving the superior efficiency of EDTA in GSR recoveries.
Abstract: This work presents a novel collection method for gunshot residues (GSR) using a sampling procedure based on ethylenediaminetetraacetic acid (EDTA) solution as a complexing agent on moistened swabs. Detection was via a sector-field inductively coupled plasma mass spectrometry (HRICP-MS). The proposed collection and analytical method allowed detection of antimony (Sb), barium (Ba) and lead (Pb) after .38 shot tests. at detection limits of less than 1 microg L(-1) in four different areas of the hands of volunteers. This paper includes a discussion concerning hand areas near the thumb and forefinger as being more suitable for GSR collection as well as a comparison between differences observed using 2% diluted EDTA. 2% nitric acid solution, and simple deionized water as collecting solutions, proving the superior efficiency of EDTA in GSR recoveries.
TL;DR: In this article, the decay constant for spontaneous fission of 238U, lf, determined by particle-track detector techniques, is presented, and a value of lf = (8.66±0.38)·10-17 y-1 is obtained.
Abstract: A value of the decay constant for spontaneous fission of 238U, lf, determined by particle-track detector techniques, is presented. The main source of systematic error in fission-track measurements of lf, the so called ‘neutron dosimetry’, has been avoided. Instead of calibrating the neutron source and the usual mica detector through tracks of 235U fission induced by thermal neutrons, spontaneous-fission tracks and alpha-particle tracks of 238U and 242Pu were used. A value of lf = (8.66±0.38)·10-17 y-1 has been obtained.
TL;DR: In this paper, Enrei and Vinton soybeans were irradiated with gamma-rays and soft-electrons at 60 keV to compare the effectiveness of the treatments for decontamination purpose.
Abstract: Soft-electron is a term referring to electrons with energies of 300 kV or lower. Enrei and Vinton soybeans were irradiated with gamma–rays and soft–electrons at 60 keV to compare the effectiveness of the treatments for decontamination purpose. The doses of 20 kGy of gamma-rays and 26 kGy of soft-electrons were effective to decontaminate the soybeans. The gamma radiation changed some properties of the grains: inhibited the germination capacity, increased the lipid oxidation and decreased the lipoxygenase activity, radical scavenging activity and carotenoid content. Soft-electron treatment caused less or none change in soybean quality, being considered a more appropriate procedure for decontamination.
TL;DR: The Pedra Preta wolframite ore deposit is hosted by a vein system that cuts rocks of the Archean Andorinhas supergroup and the cupola of the 1.88 Ga Musa granite.
TL;DR: In this article, the results of thermoluminescence (TL) ages of eight samples from Comprida Island, which corroborate the Pleistocene age assumed during mapping surveys of these deposits, are presented.
Abstract: The Cananeia (Upper Pleistocene) and the Comprida Island (Holocene) formations, outcropping in the Comprida island (SP) have been mapped using geomorphological and lithological criteria. Only one sample of the Cananeia Formation, collected in the homonymous island in front of the Comprida Island, was beyond the limit of the standard radiocarbon method. But since the publication of the geological map of the area in 1978, there has been some doubt on the real occurrence of Pleistocene deposits in southern extremity of Comprida Island. This paper deals with the results of thermoluminescence (TL) ages of eight samples from Comprida Island, which corroborate the Pleistocene age assumed during mapping surveys of these deposits. On the other hand, possible interpretations of the obtained ages, in relation to their depositional environments and related northern hemisphere Quaternary glaciations, are presented.