Enhanced broadband near-infrared luminescence in transparent silicate glass ceramics containing Yb3+ ions and Ni2+-doped Li Ga5 O8 nanocrystals

Spectral properties of Yb3+/Ni2+ codoped transparent silicate glass ceramics containing LiGa5O8 nanocrystals were investigated. The near-infrared emission intensity of Ni2+ was largely increased with Yb3+ codoping due to Yb3+-> Ni2+ energy transfer. The qualitative calculation of the energy transfer constant Cs-a and rate Ps-a showed that the Yb3+-> Ni2+ energy transfer was much greater than in the opposite direction. Yb3+/Ni2+ codoped glass ceramics with 0.75 mol % Yb2O3 exhibited a near-infrared emission with full width at half maximum of 290 nm and fluorescent lifetime of 920 mu s. The glass ceramics are promising for broadband optical amplification.

Enhanced near-infrared emission from Ni2+ in Cr3+ Ni2+ codoped transparent glass ceramics

Transparent Li2O-Ga2O3-SiO2 glass ceramics containing Cr3+/Ni2+ codoped LiGa5O8 nanocrystals were synthesized. The steady state emission spectra indicated that the near-infrared emission intensity of Ni2+ at 1300 nm in Cr3+/Ni2+ codoped glass ceramics was enhanced up to about 7.3 times compared with that in Ni2+ single-doped glass ceramics with 532 nm excitation. This enhancement in emission intensity was due to efficient energy transfer from Cr3+ to Ni2+, which was confirmed by time-resolved emission spectra. The energy transfer efficiency was estimated to be 85% and the energy transfer mechanism was discussed. (C) 2008 American Institute of Physics.

Transparent Ni2+-doped silicate glass ceramics for broadband near-infrared emission

Transparent Ni2+-doped MgO-Al2O3-Ga2O3-SiO2-TiO2 glass ceramics were fabricated. The precipitated nanocrystal phase in the glass ceramics was identified by X-ray diffraction and transmission electron microscope. Broadband near-infrared emission centered at 1220 nm with full width at half maximum of about 240 nm and lifetime of about 250 mu s was observed with 980 nm excitation. The longer wavelength emission compared with Ni2+-doped MgAl2O4 crystal was attributed to the low crystal field occupied by Ni2+ in the glass ceramics. The present Ni2+-doped transparent glass ceramics may have potential applications in broadband optical amplifiers. (c) 2007 Elsevier B.V. All rights reserved.

Blue emission from Eu2+ -doped high silica glass by near-infrared femtosecond laser irradiation

Eu2+-doped high silica glass (HSG) is fabricated by sintering porous glass which is impregnated with europium ions. Eu2+-doped HSG is revealed to yield intense blue emission excited by ultraviolet (UV) light and near-infrared femtosecond laser. The emission profile obtained by UV excitation can be well traced by near-infrared femtosecond laser. The upconversion emission excited by 800 nm femtosecond laser is considered to be related to a two-photon absorption process from the relationship between the integrated intensity and the pump power. A tentative scheme of upconverted blue emission from Eu2+-doped HSG was also proposed. The HSG materials presented herein are expected to find applications in high density optical storage and three-dimensional color displays. (c) 2008 American Institute of Physics.

Near infrared broadband emission of bismuth-doped aluminophosphate glass

Near infrared broadband emission characteristics of bismuth-doped aluminophosphate glass have been investigated. Broad infrared emissions peaking at 1210nm, 1173nm and 1300nm were observed when the glass was pumped by 405nm laser diode (LD), 514nm Ar+ laser and 808nm LD, respectively. The full widths at half maximum (FWHMs) are 235nm, 207nm and 300nm for the emissions at 1210nm, 1173nm and 1300nm, respectively. Based on the energy matching conditions, it is suggested that the infrared emission may be ascribed to P-3(1) --> P-3(0) transition of Bi+. The broadband infrared luminescent characteristics of the glasses indicate that they are promising for broadband optical fiber amplifiers and tunable lasers. (C) 2005 Optical Society of America.

Broadband near-infrared emission from transparent Ni2+-doped sodium aluminosilicate glass ceramics

Broadband neat-infrared emission from transparent Ni2+-doped sodium aluminosilicate glass-cermaics is observed. The broad emission is centered at 1290 nm and covers the whole telecommunication wavelength region (1100-1700 nm) with full width at half maximum of about 340 nm. The observed infrared emission could be attributed to the T-3(2)(F) -> (3)A(2)(F) transition of octahedral Ni2+ ions that occupy high-field sites in nanocrystals. The product of the lifetime and the stimulated emission cross section is 2.15 x 10(-24) cm(2)s. It is suggested that Ni2+-doped sodium aluminosilicate glass ceramics have potential applications in tunable broadband light sources and broadband amplifiers.

Itinerário da paternidade: a construção social da integralidade do cuidado ao recém-nascido e família na UTI- Neonatal

Esta pesquisa teve como objetivo analisar o itinerário da paternidade como uma construção social, a partir das relações estabelecidas entre os pais com os membros da instituição de saúde e as redes sociais em que se inserem. Tal construção se configurou na busca, pelo pai, de reconhecimento do exercício da paternidade, bem como suas repercussões na integralidade do cuidado ao recém-nascido de risco e sua família. Utilizamos como pressupostos conceituais para definição do itinerário da paternidade as teorias da integralidade (desenvolvidas pelo grupo LAPPIS), a teoria do reconhecimento (de Axel Honneth) e de redes sociais (de Paulo Henrique Martins). O cenário da pesquisa foi o Hospital Sofia Feldman, instituição filantrópica de direito privado localizada na periferia de Belo Horizonte, Estado de Minas Gerais. Participaram do estudo três pais que tiveram filhos internados na UTIN e seus familiares, além de profissionais, voluntários e gestores que atuam na instituição. A partir da abordagem da fenomenologia sociológica, realizaram-se entrevistas, observação dos espaços institucionais e dois grupos focais com familiares, adotando-se a Metodologia de Análise de Redes no Cotidiano (MARES) como técnica de coleta de dados. A análise dos itinerários da paternidade nos permitiu discutir as repercussões da trajetória desses pais nas dimensões da integralidade (políticas e organização dos serviços e saberes e práticas dos profissionais). Verificamos que a alta da companheira e internação do filho na neonatologia constituem uma inflexão no percurso dos pais no que concerne à questão do reconhecimento como usuário no serviço e a integralidade do cuidado à família. Além disso, identificamos que as relações estabelecidas no acolhimento desses pais pelos profissionais envolveram a negociação de saberes entre os profissionais, e destes com os usuários, que repercutiram na construção e reconstrução das práticas de cuidado na UTIN. Tais repercussões significaram, na prática, formas de inclusão do pai, que passa de uma situação de observador privilegiado do cuidado com o filho para um mediador colaborador na efetivação da integralidade da assistência do filho na UTIN. Vislumbramos o itinerário da paternidade como uma ferramenta de prática avaliativa na perspectiva do usuário amistosa à integralidade, que possibilita a revalorização da experiência e das relações entre os sujeitos, e que tem no agir em saúde o catalisador para as transformações do cuidado como exercício de cidadania.