Navegando por Palavras-chave "Glasses"

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    CaTiO3 and Ca1-3xSmxTiO3: Photoluminescence and morphology as a result of Hydrothermal Microwave Methodology
    (Elsevier Sci Ltd, 2016) Pinatti, Ivo Mateus; Mazzo, Tatiana Martelli [UNIFESP]; Goncalves, Rosana de Fatima [UNIFESP]; Varela, Jose Arana; Longo, Elson; Rosa, Ieda Lucia Viana
    Calcium titanate (CaTiO3 - CT) and samarium doped calcium titanate (CaTiO3:Sm3+ - CT:Sm) powders in different Sm3+ concentrations (0.5-5.0% molar ratio of Sm3+) were obtained by the Hydrothermal Microwave Methodology at 140 degrees C for 16 min. These crystals were structurally characterized by X-ray diffraction (XRD) and micro-Raman (MR) spectroscopy. Field emission scanning electron microscopy images were employed to observe the shape and size of the crystals. The optical properties were investigated by ultraviolet visible (UV Vis) absorption and photoluminescence (PL) measurements. The XRD indicated structural organization at long range while MR revealed short range order for all undoped and Sm-doped samples. Morphological analysis revealed a new cubic morphology for CT:Sm, presenting an average size of 3.0 mu m. Further, the ultraviolet visible absorption spectra indicated the existence of intermediary energy levels within the band gap. The maximum intensity PL emission occurred due to (4)G(5/2) -> H-6(7/2) and (4)G(5/2) -> H-6(9/2), transitions of Sm3+. CIE chromaticity coordinates of the samples were determined and support these materials are promising candidates for applications as phosphors in the visible orange range. This research concluded that the methodology employed here was responsible for the presence of unusual and interesting properties for these new luminescent materials. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
  • Nenhuma Miniatura disponível
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    Somente Metadadados
    CaTiO3 and Ca1-3xSmxTiO3: Photoluminescence and morphology as a result of Hydrothermal Microwave Methodology
    (Elsevier Sci Ltd, 2016) Pinatti, Ivo Mateus; Mazzo, Tatiana Martelli [UNIFESP]; Gonçalves, Rosana de Fátima [UNIFESP]; Varela, Jose Arana; Longo, Elson; Rosa, Ieda Lucia Viana
    Calcium titanate (CaTiO3 - CT) and samarium doped calcium titanate (CaTiO3:Sm3+ - CT:Sm) powders in different Sm3+ concentrations (0.5-5.0% molar ratio of Sm3+) were obtained by the Hydrothermal Microwave Methodology at 140 degrees C for 16 min. These crystals were structurally characterized by X-ray diffraction (XRD) and micro-Raman (MR) spectroscopy. Field emission scanning electron microscopy images were employed to observe the shape and size of the crystals. The optical properties were investigated by ultraviolet visible (UV Vis) absorption and photoluminescence (PL) measurements. The XRD indicated structural organization at long range while MR revealed short range order for all undoped and Sm-doped samples. Morphological analysis revealed a new cubic morphology for CT:Sm, presenting an average size of 3.0 mu m. Further, the ultraviolet visible absorption spectra indicated the existence of intermediary energy levels within the band gap. The maximum intensity PL emission occurred due to (4)G(5/2) -> H-6(7/2) and (4)G(5/2) -> H-6(9/2), transitions of Sm3+. CIE chromaticity coordinates of the samples were determined and support these materials are promising candidates for applications as phosphors in the visible orange range. This research concluded that the methodology employed here was responsible for the presence of unusual and interesting properties for these new luminescent materials. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
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    Prevalência e causas de deficiência visual para perto em adultos de 45 anos ou mais de idade do município de Parintins, Amazonas: estudo ocular da região amazônica brasileira
    (Universidade Federal de São Paulo (UNIFESP), 2019-05-30) Cunha, Cristina Cardoso Coimbra [UNIFESP]; Salomao, Solange Rios [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Purpose:To determine the prevalence and causes of near vision impairment in a population of adults 45 years of age and older from the Brazilian Amazon Region. Methods:This is a population- based- cross- sectional study in which cluster sampling was used in randomly selecting subjects 45 years of age and older from urban and rural areas of Parintins city, Amazonas state, Brazil. Participants underwent ophthalmic examination, including uncorrected, presenting, and bestcorrected near visual acuity from each eye; biomicroscopy; fundoscopy; and subjective refraction, including testing with additional lenses for near vision optical correction. A principal cause for near vision impairment was assigned by the ophthalmologist and presbyopia was defined as uncorrected near visual acuity ≤ 20/40 changing to > 20/40 with best-corrected near visual acuity. Free-of-charge glasses were provided for those in need. Results: A total of 2384 subjects were enumerated and 2025 had reliable near visual acuity measurements from both eyes. The prevalence of near vision impairment in the better seeing eye was 96,5% with uncorrected near visual acuity, decreasing to 81,1% with presenting near visual acuity and to 20,5% with best-corrected near visual acuity. Presbyopia was the principal cause of near vision impairment in 71,8%, followed by cataract (16,5%) and pterygium (2,5%), and was associated with younger age and high schooling. Glasses for near vision were prescribed and provided to 1414 (69,8%) participants. Conclusions: A high prevalence of near vision impairment was detected even in those wearing glasses for near. Prescription and provision of low- cost reading glasses should be considered by Brazilian health authorities to address this easily and promptly correctable formof vision impairment.