CYRO TEITI ENOKIHARA
18 resultados
Resultados de Busca
Agora exibindo 1 - 10 de 18
Artigo IPEN-doc 28280 Studies of hydrothermal quartz from Ametista do Sul treated with gamma radiation2021 - ENOKIHARA, CYRO T.; GUTTLER, RAINER A.S.; RELA, PAULO R.Artigo IPEN-doc 27880 Comparative analysis of quartz treated with gamma radiation originated from the hydrothermal geodes of the Paraná Basin, with quartz generated in the hydrothermal veins of Serra do Espinhaço2021 - ENOKIHARA, C.T.; SCHULTZ-GUTTLER, R.A.; RELA, P.R.In Brazil, hydrothermal quartz may be found in the geodes of the basaltic rocks of the Paraná Basin and in the vein systems of quartzites of the Serra do Espinhaço. The quartz of hydrothermal origin of the Paraná Basin contains a great amount of structurally bound water in the form of molecular water, silanol, hydroxyl and abundant growth defects that are responsible for the green color formed by irradiation. To register the influence of water in the formation of the green color in the quartz of the Paraná Basin, quartz samples from the following regions were analyzed: Artigas, located in the Paraná Basin, Curvelo and Brejinho located in Serra do Espinhaço. The quartz from Artigas, formed at low temperature, has high concentration of molecular water and silanol and a greater amount of Fe than Al. The quartz from Curvelo with Al, but, without water molecular and silanol was formed by intermediate temperature and the quartz from Brejinho has very little Al, Fe and a small silanol and molecular water content. To characterize these samples, ICP, NAA, and NIR-FTIR spectroscopic measurements have been taken together with water loss techniques. The analysis by FTIR spectrometry of Artigas quartz samples shows strong absorptions of H2O and Si-OH, respectively, near the regions of 5300 cm-1 and 4500 cm-1. This content of molecular water and silanol in hydrothermal quartz of Artigas is responsible for the formation of NBOHC defects that produce, by gamma radiation, the green color.Artigo IPEN-doc 26739 Gamma radiation of quartz from Entre Rios (SC) and Quaraí (RS)2019 - ENOKIHARA, C.T.; SCHULTZ-GUTTLER, R.A.; RELA, P.R.The availability of gamma ray irradiators in Brazil increased the possibilities of the treatment of gemstones for color enhancement. One of the minerals with very high potential for these treatments is the quartz, a very widespread mineral with many colored commercial varieties. There is a specific variety of quartz in nature, showing a green color that may be produced artificially, by gamma radiation (60Co). In Brazil, the widely scattered geode occurrence from Quaraí, at Brazil southernmost location up to Uberlandia, in Minas Gerais, is one of these events. Quartz from these occurrences have been formed by strong hydrothermal activities. Hence, many quartz crystals showed a very fast growth occurrence, facilitating the formation of consequent defects and the uptake of water under the form of micro inclusions, molecular water, silanol (Si-OH) and OH. In the present work, the material analyzed is from hydrothermal regimes located near the towns Entre Rios and Quaraí. To characterize these materials, analyses have been made by ICP, NAA, electron microscopy, water loss techniques plus UV-VIS and NIR-FTIR spectroscopic measurements. Silanol complexes have been found by radiation, due to gamma rays forming the color center NBOHC (Non-Bonding Oxygen Hole Center), showing absorption between 590 to 620 nm and leaving a transmission window at about 550nm, responsible for the green color. The spectroscopic water determination showed less molecular water (up to 2300 ppm, per weight), probably due to remaining silanol complexes. The water content, with up to 3200 ppm by weight, exceeds the amount of charge balancing cations (Fe, Al, Li).Artigo IPEN-doc 24183 Gamma radiation of quartz from Entre Rios (SC) and Quaraí (RS)2017 - ENOKIHARA, CYRO T.; SCHULTZ-GUTTLER, RAINER A.; RELA, PAULO R.The availability of gamma ray irradiators in Brazil increased the possibilities of treatments of gemstones for color enhancements. One of the minerals with a very high potential of these treatments is quartz, a very widespread mineral with many colored commercial varieties. A specific variety of quartz showing a green color in nature or induced artificially by radiation gamma (60Co) is quite rare. In Brazil the widely scattered geode occurrences along a 600 km stretch from Quaraí at Brazil southernmost tip to Uberlandia in Minas Gerais is one of these. Quartz from these occurrences have been formed by strong hydrothermal activities. That way much quartz crystals showed a very fast growth history facilitating the formation of growth defects and the uptake of water in form of micro inclusions, molecular water, silanol (Si-OH) and OH. In the present work the material analyzed is from hydrothermal regimes located near the towns Entre Rios (SC) and Quaraí (RS). To characterize these materials analyses have been made by ICP, NAA, electron microscopy, water loss techniques and UV-VIS and NIR-FTIR spectroscopic measurements. Silanol complexes are found, which by radiation due to gamma rays form the color center NBOHC (Non-Bonding Oxygen Hole Center), showing absorption between 590 to 620 nm and leaving a transmission window at about 550nm, responsible for the green color. The spectroscopic water determination showed less molecular water (up to 2300 ppm by weight), probably due to remaining silanol complexes.The water content with up to 3200 ppm by weight exceeds the amount of charge balancing cations (Fe, Al, Li).Publicação IPEN-doc 03085 Determinacao da vazao solida por arrasto de fundo no Rio Parana utilizando tracador radioativo1988 - AOKI, P.E.; ENOKIHARA, C.T.; ROCCA, H.C.C.; BITTENCOURT, A.V.L.Publicação IPEN-doc 03010 Determinacao de perfis de concentracoes de cesio-137 nos focos principais do acidente radiologico ocorrido em GoianiaGO1988 - ROCCA, H.C.C.; AOKI, P.E.; ENOKIHARA, C.T.; ROSTELATO, M.E.C.M.; LEPKI, V.; BAMBALAS, E.Artigo IPEN-doc 20962 Characterization of hydrothermal green quartz produced by gamma radiation2015 - ENOKIHARA, CYRO T.; SCHULTZ-GUTTLER, RAINER A.; RELA, PAULO R.Artigo IPEN-doc 19428 Development of an isotropic underwater device for color enhancement of gemstones2013 - SANTOS, PAULO S.; FERNANDES, VAGNER; ENOKIHARA, CYRO T.; CALVO, WILSON A.P.; VASQUEZ, PABLO A.S.Artigo IPEN-doc 08866 Sistema de controle e contabilidade de materiais nucleares no IPEN-CNEN/SP2002 - ARAUJO, J.A.; ENOKIHARA, C.T.Artigo IPEN-doc 16879 Montezuma prasiolite: gamma radiation effects2011 - GUTTLER, RAINER A.S.; ENOKIHARA, CYRO T.; HELFENBERGER, ANDRE F.M.; RELA, PAULO R.