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Sample records for chapada diamantina ba

  1. Fungos anamórficos (Hyphomycetes da Chapada Diamantina: novos registros para o Estado da Bahia e Brasil Anamorphic fungi (Hyphomycetes from the Chapada Diamantina: new records from Bahia State and Brazil

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    Alisson Cardoso Rodrigues da Cruz

    2007-12-01

    Full Text Available (Fungos anamórficos (Hyphomycetes da Chapada Diamantina: novos registros para o Estado da Bahia e Brasil. Os fungos anamórficos, caracterizados pela produção de estruturas de reprodução assexuadas, são habitantes comuns do folhedo onde desempenham papel importante na decomposição. O objetivo deste trabalho foi realizar um inventário dos fungos anamórficos associados ao folhedo de plantas da Chapada Diamantina, BA. Foram realizadas 13 expedições, de dezembro/2002 a outubro/2003, para coleta de folhedo. Para verificação da presença de fungos anamórficos o material foi submetido à técnica de lavagem sucessiva com água destilada esterilizada e posteriormente incubado em câmaras-úmidas. Lâminas permanentes com as estruturas reprodutivas dos espécimes foram confeccionadas com resina PVL e depositadas no herbário HUEFS. Das 57 espécies de fungos anamórficos identificados, nove constituem novas ocorrências para o Estado da Bahia e cinco para o Brasil: Fusariella atrovirens (Berk. Sacc., Kiliophora ubiensis (Caneva & Rambelli Kuthub. & Nawawi, Paraceratocladium silvestre Castañeda, Pleurotheciopsis setiformis Castañeda e Triscelophorus deficiens (Matsush. Matsush. Incluem-se comentários e distribuição geográfica dos novos registros para o Estado da Bahia; descrições e ilustrações são apresentadas para as novas ocorrências para o Brasil.(Anamorphic fungi (Hyphomycetes from the Chapada Diamantina: new records from Bahia State and Brazil. The anamorphic fungi are characterized by production of asexual reproductive structures and are common inhabitants of the leaf litter, where they play an important role in decomposition. The aim of this work was to survey the anamorphic fungi associated with leaf litter from Chapada Diamantina, B ahia state. Thirteen expeditions took place from December/2002 to October/2003 to collect leaf litter. The serial washing technique with sterile distilled water followed by incubation in

  2. Diversidade arbórea das florestas alto montanas no Sul da Chapada Diamantina, Bahia, Brasil Tree diversity of high montane forests in Southern Chapada Diamantina, Bahia, Brazil

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    Francisco Haroldo Feitosa do Nascimento

    2010-09-01

    Full Text Available A região do extremo Sul da Chapada Diamantina abriga as maiores altitudes do Nordeste brasileiro. Situam-se nessas serras as maiores elevações da região Nordeste, entre elas, o Pico do Barbado (2.033 m.s.n.m.. Dois dos rios mais importantes da Bahia nascem nestas serras: o Rio de Contas e o Rio Paramirim. A região é bem conhecida botanicamente, porém, este foi o primeiro inventário quantitativo realizado enfocando as formações florestais. Comparou-se a composição florística de 12 fragmentos de floresta montana, entre 1.350 e 1.750 m.s.n.m., tendo sido amostrados os indivíduos com PAP> 8 cm. Registrou-se a presença de 116 espécies em 84 gêneros de 48 famílias. As famílias com maior número de espécies foram Myrtaceae (N=20 e Lauraceae (N=10. Os gêneros com maior número de espécies foram Ocotea (N=7, Myrcia (N=5, Eugenia (N=4 e Miconia (N=4. A maioria das espécies apresentou padrão de distribuição amplo, mas foram encontradas espécies comuns a formações florestais de altitude do Sudeste e Sul do Brasil, como Drimys brasiliensis Miers (Winteraceae e Weinmannia paulliniifolia Pohl (Cunnoniacae. A flora dos fragmentos estudados compartilha baixo número de espécies com as formações estacionais deciduais do entorno da Chapada Diamantina, indicando que estas florestas são únicas e merecem atenção especial, para sua conservação.The southernmost region of Chapada Diamantina, nearest to Rio de Contas harbours the highest peaks of the Brazilian northeastern region, including Pico do Barbado (2,033 m.a.s.l. and the source of the two important rivers in Bahia state (Rio de Contas and Rio Paramirim. The region is well known botanically. This was the first quantitative study to survey the floristic composition of 12 fragments of montane forests (1,350 m.a.s.l. to 1750 m.a.s.l. including trees > 8 cbh. A total of 117 species, 84 genera and 48 families were found. The richest families were Myrtaceae (N=20 and Lauraceae (N

  3. Dating low-grade metamorphism and deformation of the Espinhaço Supergroup in the Chapada Diamantina (Bahia, NE Brazil: a K/Ar fine-fraction study

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    Annette Süssenberger

    Full Text Available This study focuses on the northernmost part of the Mesoproterozoic Espinhaço Supergroup that crops out in the Chapada Diamantina. The fine-fraction K/Ar dating obtained on slightly metamorphosed sediments of the siliciclastic Espinhaço Supergroup shows a polyphase deformation history that corresponds to the Brasiliano (Pan-African orogenic cycle. The isotopic results are interpreted to indicate three age domains coincident with three structurally different domains. Constrained by the Kübler Index ('illite crystallinity' and illite polytypism, the thermal conditions generated during the tectonic activity show a gradual trend from the craton margins to the interior from epizonal to diagenetic. The northern Chapada Diamantina is situated in the foreland of the Riacho do Pontal belt and comprises the sediments of the Espinhaço Supergroup northeast of the Irecê basin. The K/Ar ages for < 2 µm illite fractions range between 645 and 621 Ma [mean 637±9 Ma (2s] and for < 0.2 µm fraction range between 625 and 603 Ma [mean 614±9 Ma (2s]. Samples from the central Chapada Diamantina east of the Irecê basin are not affected by a Brasiliano deformation event and therefore, the N-S-trending structures are assumed to be older. The deformation of the southern Chapada Diamantina was established in conjunction with the formation of the Araçuai orogenesis and the inversion and reactivation of the Paramirim impactogen. The last stage of deformation in this area is recorded by the K/Ar fine-fraction dating between 470 and 460 Ma.

  4. Species richness and distribution of bryophytes within different phytophysiognomies in the Chapada Diamantina region of Brazil

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    Emilia de Brito Valente

    2013-06-01

    Full Text Available The Chapada Diamantina ecoregion is within the caatinga (shrublands biome of Brazil. Environmental factors determine the phytophysiognomies that distinguish the ecoregion from the surrounding areas. This study aimed to investigate the distribution of bryophyte flora in this ecoregion, by phytophysiognomy and elevational zone. Analyzing specimens we collected from five municipalities in the region, together with specimens (previously collected from the region in herbaria, we identified 400 taxa. The phytophysiognomies that presented the highest species richness and the greatest numbers of exclusive taxa were forests and campos rupestres (dry, rocky grasslands, which respectively accounted for 51% and 40% of the taxa, compared with only 5% and 4%, respectively, for the caatinga and cerrado (savanna. Species richness and the numbers of exclusive taxa were highest in the lower and upper montane zones. There was a predominance of neotropical taxa and a significant number of disjunct species found in Brazil and in the Andes region. We conclude that the Chapada Diamantina region is an important center of bryophyte diversity, harboring not only a great number of species overall but also a considerable number of species exclusive to the region, primarily in forests and campos rupestres at elevations above 800 m.

  5. Campo rupestre recém-queimado na Chapada Diamantina, Bahia, Brasil: plantas de rebrota e sementes, com espécies endêmicas na rocha Recently burnt 'campo rupestre' in the Chapada Diamantina, Bahia, Brazil: resprouters and seeders, with endemic rock species

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    Sâmia Paula Santos Neves

    2010-09-01

    Full Text Available O fogo é um distúrbio recorrente em muitas áreas da Chapada Diamantina, geralmente originado por ação antrópica e que ocasiona rápidas mudanças nas comunidades. Este trabalho objetiva conhecer a composição e estrutura da vegetação de uma área de campo rupestre recém-queimada no Parque Nacional da Chapada Diamantina, Bahia, Brasil, situada entre 700 e 800 m acima do nível do mar, visando discussão das estratégias de regeneração das espécies mais conspícuas e das similaridades florísticas entre áreas com e sem distúrbio recente de fogo. Foi realizado um censo das espécies de plantas vasculares ocorrentes em 16 parcelas de 10x10 m, sendo as coberturas estimadas em cinco subparcelas de 2x2 m de cada parcela. Foram encontradas 85 espécies de 34 famílias, sendo 11 de monocotiledôneas, 22 de eudicotiledôneas e uma de monilófita. A espécie mais abundante foi Panicum trinii Kunth (Poaceae e a mais frequente Periandra mediterranea (Vell. Taub. (Fabaceae. O índice de Shannon foi 3,4. A área estudada agrupou-se com a área de afloramento rochoso em altitude menos elevada (38% de similaridade. É possível que o fogo seja mais frequente nessas áreas menos isoladas, em relação às dos topos de morros. As espécies dominantes se restabeleceram principalmente a partir de gemas de sistemas subterrâneos e aéreos. Uma das espécies mais frequentes, Dactylaena microphylla Eichler, estabeceu-se de sementes. Espécies endêmicas sensíveis à ação do fogo sobrevivem em ilhas de vegetação nos afloramentos rochosos.Fire is a recurrent disturbance in many areas of Chapada Diamantina, generally set by human activity that drives rapid changes in communities. This study aims to investigate the composition and structure of 'campo rupestre' vegetation in a recently burned area, between 700 and 800 m above sea level, at Chapada Diamantina National Park, Bahia, Brazil, and to discuss the strategies of regeneration for the most

  6. Metallogenetic modeling for uranium exploration in rocks of the Abaira-Jussiape Anticlinal nucleus, Chapada Diamantina, Bahia; Modelagem metalogenetica para prospeccao de uranio nas rochas do nucleo da Anticlinal Abaira-Jussiape, Chapada Diamantina, Bahia

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    Santana, Jocilene dos Santos; Cruz, Simone Cerqueira Pereira; Barbosa, Johildo Salomao Figueiredo [Universidade Federal da Bahia (PPGG/UFBA), Salvador, BA (Brazil); Abram, Maisa Bastos; Martins, Adriano Alberto Marques, E-mail: jocilenesanttana@yahoo.com.br, E-mail: simonecruzufba@gmail.com, E-mail: johildo@cpgg.ufba.br, E-mail: maisa.abram@cprm.gov.br, E-mail: adriano1952@gmail.com [Companhia de Pesquisas de Recursos Minerais (CPRM), Salvador, BA (Brazil). Superintendencia Regional de Salvador. Servico Geologico do Brasil

    2011-06-15

    The NNW-SSE-trending Abaira-Jussiape Anticlinal is an antiformal culmination of folding and shearing in the Paramirim Corridor of the Western Chapada Diamantina. In its core paleoproterozoic, mylonitized Caraguatai Suite, tonalites-granodiorites, alkali-feldspar granites, syenites to quartz-syenites and Jussiape Suite granites crop out. Compressional and distensional stresses mark the structural geology of the area. The compressional structures are related to two distinct deformation phases, named D1a and D1b. The main compressional phase is ductile D1a, which is related to the nucleation of dextral to dextral-reverse shearing zones. Deformation and syn-D1a recrystallization involving plagioclase and the K-feldspar suggest deformation temperature conditions above 550 deg C. The following phase D2 is of ductilebrittle nature and culminates in reverse shearing zones. The distensional structures correspond to the D3 phase and are represented by frontal shear zones with normal movement. The petrographic study helped identify a pre-D1a hydrothermal alteration process related to albitization and potassification, syn-D1 oxidation process, and hydration and saussuritization related to phases D2 and D3. The integration of lithological, petrographic, structural and geophysical data by means of the logic Fuzzy, plus the existing information regarding structural and lithologic controls of the known uranium mineralization in the Paramirim Corridor, led us to identify two promising areas for radioactive element exploration in the nucleus of Abaira-Jussiape Anticlinal. (author)

  7. Beija-flores (Aves: Trochilidae e seus recursos florais em uma área de caatinga da Chapada Diamantina, Bahia, Brasil Hummingbirds (Aves: Trochilidae and their floral resources in an area of caatinga vegetation in the Chapada Diamantina, Bahia State, Northeast Brazil

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    Caio Graco Machado

    2009-06-01

    Full Text Available This study investigated the species of hummingbird occurring in an area of caatinga vegetation, examining their seasonal activities, the assemblages of plants that they used, as well as the floral characteristics and flowering phenology of that vegetation. These surveys were performed in an area of arboreal caatinga in Chapada Diamantina, municipality of Mucugê, state of Bahia, Brazil, during 12 expeditions undertaken on a bi-monthly basis between October, 2005 and August, 2007. Field activities included observations made of the visiting hummingbird species, their behavior, and the frequency of their visits; as well as the plant species visited, their floral attributes, size, and the flowering phenophase evident on the occasion of each expedition. Seven species of hummingbirds were registered, including five residents. Phaethornis pretrei (Lesson & Delattre, 1839 acted as the organizer of this pollination guild. This species and Chlorostilbon lucidus (Shaw, 1812, these two species were considered the principal pollinators within the community. The hummingbirds visited a total of 29 plant species, of which only 12 are considered ornitophilous. The plant community presented a continuous flowering, with 19 species flowering in both the dry and the rainy season, permitting the year-round permanence of resident hummingbird species.

  8. Description of a new species of Characidium Reinhardt, 1867 (Characiformes: Crenuchidae) from the Chapada Diamantina, Bahia, and redescription of Characidium bimaculatum Fowler, 1941.

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    Melo, Marcelo R S; Espíndola, Vinicius C

    2016-11-24

    A new species of Characidium Reinhardt, 1867 endemic to tributaries of the upper rio Paraguaçu in the Chapada Diamantina, Bahia, Brazil, is described. The new species can be distinguished from its congeners except C. bahiense, C. bimaculatum, C. laterale, C. nana, C. nupelia, and C. xavante, by having a conspicuous peduncular blotch in addition to the basicaudal spot on the base of the middle caudal-fin rays. Among other features, the new species differs from C. bahiense, C. laterale, C. nana, C. nupelia, and C. xavante by having a complete lateral line with 32-36 perforated scales (vs. lateral line short, with 9-11 perforated scales), and from C. bimaculatum by the body pigmentation pattern, with secondary bars present (vs. absent), total bars 11-16 (vs. 10-12), peduncular blotch rounded (vs. horizontally elongated), and mature males not having a darker dorsal fin (vs. proximal third of dorsal fin darker in mature males). Characidium bimaculatum, a poorly known species from Northeastern Brazil, is redescribed.

  9. Metallogenetic modeling for uranium exploration in rocks of the Abaira-Jussiape Anticlinal nucleus, Chapada Diamantina, Bahia

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    Santana, Jocilene dos Santos; Cruz, Simone Cerqueira Pereira; Barbosa, Johildo Salomao Figueiredo; Abram, Maisa Bastos; Martins, Adriano Alberto Marques

    2011-01-01

    The NNW-SSE-trending Abaira-Jussiape Anticlinal is an antiformal culmination of folding and shearing in the Paramirim Corridor of the Western Chapada Diamantina. In its core paleoproterozoic, mylonitized Caraguatai Suite, tonalites-granodiorites, alkali-feldspar granites, syenites to quartz-syenites and Jussiape Suite granites crop out. Compressional and distensional stresses mark the structural geology of the area. The compressional structures are related to two distinct deformation phases, named D1a and D1b. The main compressional phase is ductile D1a, which is related to the nucleation of dextral to dextral-reverse shearing zones. Deformation and syn-D1a recrystallization involving plagioclase and the K-feldspar suggest deformation temperature conditions above 550 deg C. The following phase D2 is of ductilebrittle nature and culminates in reverse shearing zones. The distensional structures correspond to the D3 phase and are represented by frontal shear zones with normal movement. The petrographic study helped identify a pre-D1a hydrothermal alteration process related to albitization and potassification, syn-D1 oxidation process, and hydration and saussuritization related to phases D2 and D3. The integration of lithological, petrographic, structural and geophysical data by means of the logic Fuzzy, plus the existing information regarding structural and lithologic controls of the known uranium mineralization in the Paramirim Corridor, led us to identify two promising areas for radioactive element exploration in the nucleus of Abaira-Jussiape Anticlinal. (author)

  10. Composição florísitica e fitossociologia de uma área de caatinga em Contendas do Sincorá, Bahia, microrregião homogênea da Chapada Diamantina Floristic and fitosociological survey of a caatinga area at "Contendas do Sincorá", Bahia State, a homogeneous microregion of the Chapada Diamantina

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    Paulo César Fernandes Lima

    1998-01-01

    Full Text Available Objetivou-se levantar a cobertura vegetal de 11.034ha da Fazenda Extrema-Lapinha, 295 a 380m de altitude (13º46' a 14ºS e 41º3' a 41º10'W, Contendas do Sincorá, BA, na Chapada Diamantina. O clima é do tipo BSwh', estépico, semi-árido quente, com precipitação anual de 500-700mm, período chuvoso de novembro a janeiro, temperatura média de 23ºC e umidade relativa de 60-80%. Predominam os solos Podzólicos Vermelho-Amarelo Equivalente Eutrófico e solos Litólicos Eutróficos, em relevo levemente ondulado. Foram distribuídas aleatoriamente 100 parcelas de 20x5m, sendo inventariadas as plantas com DAP > a 5cm. Foram encontrados 2.897 indivíduos abrangendo 71 espécies, 51 gêneros e 23 famílias botânicas, não sendo identificados 3,59% dos mesmos. As famílias Euphorbiaceae (15,67%, Mimosaceae (13,80%, Bignoniaceae (12,35%, Caesalpiniaceae (7,14%, Boraginaceae (6,63%, Polygonaceae (6,63%, Anacardiaceae (6,04%, Burseraceae (4,93%, Apocynaceae (4,59% e Combretaceae (4,28% correspondem a 82,09% dos indivíduos inventariados. Para as classes de diâmetro inventariadas, as Cactaceae corresponderam a 0,48%, sugerindo ser esta vegetação de caatinga de caráter xerófilo pouco acentuado. As 10 espécies mais importantes, determinadas pelo índice de valor de importância, foram Commiphora leptophloeos (22,28, Croton zehntneri (19,39, Mimosa sp. (17,24, Tabebuia spongiosa (16,99, Myracrodruon urundeuva (15,38, Anadenanthera tnacrocarpa (14,25, Coccoloba termiflora (11,73, Caesalpinia sp. (11,17, Cordia sp. (10,79 e Tabebuia sp. (10,20.The aim of this work was to conduct a floristic and phytosociological survey on 11,034 hectares of the Extrema Lapinha Farm (13º46' to 14º S and 41º03' to 41º10' W, altitude from 295 to 380m, in the town of "Contendas do Sincorá", in Chapada Diamantina, Bahia State. The climate is of the BSwh' type, hot semi-arid, with an annual rainfall of 500-700mm, the rainy season being from November to January, with

  11. Características petrográficas e químicas das rochas encaixantes das mineralizações auríferas do depósito Lavra Velha (Região de Ibitiara, borda oeste da Chapada Diamantina, Bahia)

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    Carlin, Aline de Cassia [UNESP

    2016-01-01

    O depósito de ouro Lavra Velha, que pertence ao Alvo de Prospecção Lavra Velha, da empresa Yamana Gold, localiza-se na cidade de Ibitiara, centro-oeste do Estado da Bahia e borda oeste do domínio fisiográfico da Chapada Diamantina, situado no Aulacógeno do Paramirim, na região norte do Cráton São Francisco. O depósito foi recentemente inserido na classe de modelo IOCG (Iron Oxide Cooper Gold), onde a mineralização de ouro se hospeda em brechas hematíticas sericitizadas. O principal objetivo d...

  12. Análise Geoambiental de uma microbacia hidrográfica no município de Lençóis, Chapada Diamantina (Bahia, Brasil / Geoenvironmental analysis of a small watershed in municipality of Lençóis, Chapada Diamantina (Bahia, Brazil

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    Jonatas Batista Mattos

    2017-05-01

    Full Text Available Este estudo teve como objetivo o levantamento da fisiografia e do uso do solo na microbacia do Rio Lençóis, com o intuito de constituir um instrumento de gestão dos recursos naturais. Esta microbacia, localiza-se no município de Lençóis, Chapada Diamantina, estado da Bahia, Região Nordeste do Brasil. As águas drenadas por esta microbacia são destinadas ao abastecimento hídrico da cidade. A metodologia empregada se fundamentou em teorias e métodos geossistêmicos e no uso do geoprocessamento e sensoriamento remoto. Os resultados indicaram que a microbacia do Rio Lençóis é alongada, com uma hidrografia pouco ramificada e esparsa. A tipologia climática é tropical de altitude, e a litologia é predominantemente metassedimentar, com uma geologia estrutural enviesada por falha transcorrente, que controla o canal fluvial principal. A geomorfologia é composta por serras, vales e terraços fluviais, com declividade média de 27,5%. A classe de cobertura vegetal predominante é o campo rupestre. Os níveis de preservação da cobertura vegetal, detectados no mapeamento, fornecem garantias de proteção ao sistema fluvial, resguardando assim, a boa condição natural das unidades geoambientais predominantes. Na interface geossistêmica, a microbacia do Rio Lençóis apresenta características físico-ambientais que sugerem um gerenciamento direcionado para conservação, a fim de garantir o uso equilibrado dos recursos naturais que promova recursos socioeconômicos.

  13. Allozyme diversity and morphometrics of Melocactus paucispinus (Cactaceae) and evidence for hybridization with M. concinnus in the Chapada Diamantina, North-eastern Brazil.

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    Lambert, Sabrina Mota; Borba, Eduardo Leite; Machado, Marlon Câmara; Da Silva Andrade, Sónia Cristina

    2006-03-01

    Melocacatus paucispinus (Cactaceae) is endemic to the state of Bahia, Brazil, and due to its rarity and desirability to collectors it has been considered threatened with extinction. This species is usually sympatric and inter-fertile with M. concinnus, and morphological evidence for hybridization between them is present in some populations. Levels of genetic and morphological variation and sub-structuring in populations of these species were assessed and an attempt was made to verify the occurrence of natural hybridization between them. Genetic variability was surveyed using allozymes (12 loci) and morphological variability using multivariate morphometric analyses (17 vegetative characters) in ten populations of M. paucispinus and three of M. concinnus occurring in the Chapada Diamantina, Bahia. Genetic variability was low in both species (P = 0.0-33.3, A = 1.0-1.6, H(e) = 0.000-0.123 in M. paucispinus; P = 0.0-25.0, A = 1.0-1.4, H(e) = 0.000-0.104 in M. concinnus). Deficit of heterozygotes within the populations was detected in both species, with high values of F(IS) (0.732 and 0.901 in M. paucispinus and M. concinnus, respectively). Evidence of hybridization was detected by the relative allele frequency in the two diaphorase loci. High levels of genetic (F(ST) = 0.504 in M. paucispinus and 0.349 in M. concinnus) and morphological (A = 0.20 in M. paucispinus and 0.17 in M. concinnus) structuring among populations were found. The Melocactus spp. displayed levels of genetic variability lower than the values reported for other cactus species. The evidence indicates the occurrence of introgression in both species at two sites. The high F(ST) values cannot be explained by geographical substructuring, but are consistent with hybridization. Conversely, morphological differentiation in M. paucispinus, but not in M. concinnus, is probably due to isolation by distance.

  14. Padrão de Nidificação de Monobia angulosa Saussure (Vespidae Durante Estação Seca Prolongada na Região da Chapada Diamantina, Bahia, com Notas Sobre Nidificação em Ninho Abandonado de Xylocopa cearensis Ducke (Apidae

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    Thiago Mahlmann

    2015-03-01

    Abstract. Weather can be treated as an important factor in the nesting pattern of several solitary wasps species. Nesting pattern of wasp Monobia angulosa Saussure (Vespidae: Eumeninae was accessed in present study in the agricultural area of Mucugê-Ibicoara, Chapada Diamantina, Bahia, during an extended period of dry season. In here we also presented the first record of a natural nest in pre-existing cavities prior used by Xylocopa (Neoxylocopa cearensis Ducke (Apidae: Xylocopinae. For a description of the M. angulosa’s natural nest a single nest found in apple orchard (Malus domestica Borkh was used. For the nesting pattern study we used the trap nests technique with 25 points along the agricultural sampled area; traps were placed in remaining native vegetation. Each sample point was at least 4 km apart. Emerged in the laboratory a total of 19 females and 23 males for a total of 19 established nests, males emerged prior females. Unlike the horizontal trap nests, the natural one was built in vertical linear series and a wooden stake was used as a substrate. Nesting concentrated in the warmer months, between February and April, 2012, with very low precipitation, evidencing influence on nesting pattern of this species, probably due fast response to climatic changes.

  15. CHAPADAS DO BRASIL: ABORDAGEM CIENTÍFICA E CONCEITUAL

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    Fernanda Pereira Martins

    2016-03-01

    Full Text Available Chapadas são formas de relevo de grande extensão espacial e localizadas nas regiões Nordeste, Centro-Oeste e Sudeste do Brasil. Apesar de sua importância ecológica e econômica, elas carecem de uma conceituação científica clara e de consenso entre os pesquisadores brasileiros. Este fato atinge diretamente a proteção dessas geoformas, pois a legislação responsável está repleta de falhas e não encontra bases científicas que as dê suporte, dificultando sua aplicação à realidade. O objetivo deste trabalho foi o de criar um conceito científico de chapadas com o método Delphi, utilizando a opinião de diversos especialistas sobre o tema. Foram aplicados dois questionários, nos quais foram discutidos diversos parâmetros e sua respectiva importância na classificação de uma geoforma como chapada. Concluiu-se que chapadas são geoformas dotadas de características peculiares quanto à declividade de seu topo e de sua borda; categoria litológica; mergulho de camadas; processos de formação e altitude. Por fim, concluiu-se que é possível se criar um conceito científico de chapada que pode colaborar com a legislação ambiental e compatível com a realidade de ocorrência dessa geoforma no Brasil.

  16. Morcegos da Chapada do Araripe, nordeste do Brasil

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    Roberto Leonan Morim Novaes

    2014-01-01

    Full Text Available A Chapada do Araripe é um planalto localizado dentro do domínio da Caatinga no nordeste brasileiro entre os Estados do Ceará, Pernambuco e Piauí. Possui uma grande variação altimétrica, o que confere uma variedade de fitofisionomias e uma dinâmica ambiental distinta das demais áreas de Caatinga. Com o objetivo de incrementar as parcas informações sobre a biodiversidade da Caatinga apresentamos aqui o resultado de um levantamento de espécies de morcegos, realizado entre 2010 e 2012, em cinco localidades da Chapada do Araripe, nos municípios de Barbalha e Jardim, no Ceará, e Serrita, em Pernambuco. Nosso levantamento registrou 25 espécies distribuídas em seis famílias, resultante da captura de 201 indivíduos. A amostragem registrou quatro novas ocorrências para o Estado do Ceará, Sturnira tildae, Pteronotus gymnonotus, Cynomops planirostris e Promops nasutus. Uma compilação da literatura revelou que na Chapada do Araripe ocorrem 49 espécies de morcegos distribuídas em oito famílias, o que representa 64% das espécies de morcegos da Caatinga.

  17. A construção do espaço: o caso de Itaberaba

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    Marcos Sampaio Brandão

    2009-08-01

    Full Text Available O recorte espacial que este escrito se atém é o sertão baiano, em uma região entre o Recôncavo e a Chapada Diamantina, no médio Paraguaçu, denominada de Orobó, onde está situada a cidade de Itaberaba (266km de Salvador, analisada aqui desde quando era uma simples fazenda, passando pela concentração em arraial ou povoado, seu crescimento para freguesia, posteriormente classificada como vila, até o seu espaço intraurbano elevar-se à categoria de cidade. Abstract SPACE CONSTRUCTION: THE ITABERABA CASE The space clipping limited by this work is the hinterland of Bahia, specifically a place between Recôncavo and Chapada Diamantina, in mid Paraguaçu River called Orobó, where lays the city of Itaberaba (266 km distant from Salvador which progression is analysed from farm to village, from village to town and later on having it’s intra-urban space condition qualified as a city.

  18. EDUCAÇÃO AMBIENTAL E TURISMO EDUCACIONAL NA REGIÃO DA CHAPADA DIAMANTINABA

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    Fredson Pereira Silva

    2017-08-01

    Este estudio presenta el gran potencial turístico de los paisajes naturales de Lençóis, Iraquara y Mucugê, resultantes de la biodiversidad y geodiversidad local. Esa diversidad permite la realización de clases de campo, ya que es posible ver varias formaciones geológicas y geomorfológicas que son testigos de diferentes eventos geológicos, así como la presencia de la transición de los biomas Caatinga, Cerrado y Mata Atlántica, destacando el potencial pedagógico existente en esta zona. El objetivo de la investigación fue describir el potencial turístico y educativo de unos paisajes presentes en los municipios antes mencionados y su relación con la educación ambiental. El método científico utilizado fue el exploratorio, siguiendo los siguientes pasos metodológicos: revisión de la literatura de los aspectos físicos, económicos y sociales; trabajo de campo y discusión de los resultados. Es notable el crecimiento del turismo en esta región, que fue proporcionada por numerosos elementos naturales como las formaciones rocosas, cuevas, cascadas, entre otros, que contribuyen al desarrollo y el aumento de los ingresos para la población local. La actividad turística también contribuye al aprendizaje, lo que permite al visitante a entender la dinámica del paisaje y la importancia de la conservación del medio ambiente natural, porque el turismo no debe ser restringido sólo al ocio, sino también la educación ambiental. Palabras clave: Paisaje; Clase de Campo; Enseñanza.

  19. Intestinal parasites in paper money circulating in the city of Diamantina (Minas Gerais, Brazil

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    Costa MA

    2018-05-01

    Full Text Available Marina A Costa,1 Layane M Teodoro,1 Gustavo H Bahia-de-Oliveira,2 Ana Paula N Nunes,3 Ricardo A Barata1 1Laboratório de Parasitologia, Departamento de Ciências Biológicas, Universidade Federal dos Vales dos Jequitinhonha e Mucuri, Diamantina, MG, Brazil; 2Laboratório de Doenças Parasitárias, Departamento de Farmácia, Universidade Federal dos Vales dos Jequitinhonha e Mucuri, Diamantina, MG, Brazil; 3Laboratório de Bioestatística e Epidemiologia, Departamento de Ciências Básicas, Universidade Federal dos Vales dos Jequitinhonha e Mucuri, Diamantina, MG, Brazil Background: Banknotes are objects of great turnover and diffusion among the population, and can be efficient mechanisms in the dissemination of several intestinal parasites. This study investigated the presence of biological forms of intestinal parasites present in circulating cash banknotes in the city of Diamantina, Minas Gerais, Brazil, aiming to propose interventions aimed at improving local public health. Materials and methods: Between February and April 2017, samples of banknotes collected in five commercial establishments of the city were analyzed, namely: 1 gas station, 2 supermarket, 3 butchery, 4 pharmacy and 5 free fair. Ten circulating banknotes of each value (R$2.00, R$5.00, R$10.00, R$20.00, R$50.00 and R$100.00 were exchanged for new banknotes, washed with Tween 80 and, after spontaneous sedimentation, analyzed under an optical microscope with a magnification of 10× and 40×. Results: Cysts of Entamoeba coli (74.60%, cysts of Endolimax nana (16.94%, Giardia lamblia cysts (4.44%, unidentified nematode larvae (2.02%, Hymenolepis sp. (0.81%, Taenia sp. (0.81% and Ancylostomidae larvae (0.40% were found. Conclusions: The results revealed the need for improvements in basic sanitation, health and education activities that emphasized the importance of proper hand hygiene. Keywords: intestinal parasites, banknotes, Diamantina

  20. Relações pedomorfogeológicas nas chapadas elevadas do Distrito Federal Pedomorphogeological relations in the chapadas elevadas of the Distrito Federal, Brazil

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    Inara Oliveira Barbosa

    2009-10-01

    Full Text Available A caracterização pedológica e o entendimento das relações entre pedologia, geologia e geomorfologia são importantes para a compreensão da distribuição dos solos numa paisagem. O objetivo deste estudo foi avaliar as relações pedomorfogeológicas na região das Chapadas Elevadas do Distrito Federal (DF, mediante caracterização química, física, mineralógica e geoquímica dos solos de ocorrência nesse compartimento da paisagem. Foram selecionadas duas topossequências representativas da distribuição pedológica nas Chapadas Elevadas do DF, cujos solos foram formados a partir de rochas metassedimentares do Grupo Paranoá, representados por Latossolos Vermelhos (LV, Latossolos Vermelho-Amarelos (LVA e Cambissolos (C. Os Latossolos das duas topossequências apresentaram a maioria dos atributos físicos, químicos e mineralógicos semelhantes. A variação da cor nesses Latossolos é proveniente da mineralogia diferenciada dos óxidos de Fe - hematita predominante nos LV e goethita nos LVA. No entanto, as análises por meio de ICP-AES apresentaram teores de Fe2O3 similares nos Latossolos, demonstrando material de origem (rochas metassedimentares de composição geoquímica semelhante. A formação da goethita nos LVA foi considerada dependente da sua posição geomorfológica de desenvolvimento, nas bordas das chapadas, onde a oscilação do lençol freático proporcionou a formação de horizonte litoplíntico, com consequente deficiência das condições de drenagem. Os Cambissolos apresentaram-se quimicamente semelhantes aos Latossolos em razão do material de origem, que são rochas metassedimentares já pré-intemperizadas. O estudo das relações pedomorfogeológicas permitiu constatar que a distribuição dos solos nas Chapadas Elevadas do Distrito Federal é condicionada pela evolução geomorfológica e pela geologia da região.Detailed studies of pedologic characterization, as well as of relationships between pedology

  1. Geochemistry and meaning of the geotectonic position of plutonic rocks from Chapada region, Goias, Brazil

    International Nuclear Information System (INIS)

    Kuyumjian, R.M.

    1989-01-01

    In common with other orogenic belts, in which the presence of both, granitic and small basic-ultrabasic intrusions are characteristics of medium-high pressure metamorphic terranes, the geological and geochemical evidences indicate a close relationship between the granitoid, gabbroic and pyroxenitic plutons and the orogenic metabasaltic rocks from the Chapada volcano-sedimentary sequence. The granitoids are tonalitic and, on discriminant diagrams, they plot in the volcanic arc and pre-collisional fields. They display geochemical characteristics similar to the Jamaican oceanic arc-related granities. They show low LIL and HSF element abundances, low (Ta, Nb)/(K, La, etc) ratios and very low concentrations of Th, Hf, K and Y, when compared to patterns of calkaline, alkali-calcic and alkaline-peralkaline granitoids of magmatic arcs. These chemical features are characteristic of immature island arcs mantle-derived intrusives. The Chapada olivine gabbro has a chondrite-normalized spidergram, closely resembling those of island-arc basaltic lavas, the compositions of its coexisting olivine and plagioclase been similar to those from arc-related cumulate gabbros, and therefore, it could be the plutonic equivalent of the arc volcanics in the Chapada region. It is suggested that the evolution of the granitoids and gabbro intrusives from Chapada are related to a process of subduction that occurred in central Brazil during the Brasiliano/Pan-African event. (author) [pt

  2. Pollination of Cambessedesia wurdackii in Brazilian campo rupestre vegetation, with special reference to crepuscular bees.

    Science.gov (United States)

    Franco, Emanuella Lopes; Gimenes, Miriam

    2011-01-01

    Cambessedesia wurdackii Martins (Myrtales: Melastomataceae) is presumably endemic to the Chapada Diamantina, Bahia State, Brazil. A majority of the species of this family are pollinated by diurnal bees that buzz the floral anthers to collect pollen. The present work examined the interactions between C. wurdackii and visiting bees, focusing on temporal, morphological, and behavioral features, especially in regards to the crepuscular bees Megalopta sodalis (Vachal) (Hymenoptera: Halictidae) and Ptiloglossa off. dubia Moure (Hymenoptera: Colletidae). The study was undertaken in an area of campo rupestre montane savanna vegetation located in the Chapada Diamantina Mountains of Bahia State, Brazil, between August/2007 and July/2008. Flowering in C. wurdackii occurred from April through July, with a peak in May. A total of 592 visits by diurnal and crepuscular bees to the flowers of C. wurdackii were recorded, with a majority of the visits made by M. sodalis and P. dubia (92%) near sunrise and sunset. The anthers of C. wurdackii are arranged in two tiers, which favors cross pollination. The morphological, temporal and behavioral characteristics of M. sodalis and P. dubia indicated that they were potential pollinators of C. wurdackii, in spite of the fact that the colorful and showy flowers of this species are more typical of a diurnal melittophilous pollination syndrome.

  3. As RPPNs como estratégia para a conservação da biodiversidade: O caso da chapada dos veadeiros / RPPNs as a Strategy for the Conservation of Biodiversity: The Case of the Chapada dos Veadeiros

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    Priscylla Cristina Alves de Lima

    2014-04-01

    Full Text Available The Private Natural Heritage Reserves - RPPNs – are units of conservation for sustainable use on private property created on a voluntary work. The restrictions which they are supposed to follow become them as similar as the fully units protected. Thus, they can promote the conservation of their habitats without a big human intervention. The Chapada dos Veadeiros, a region located in the northeast of Goiás, has 15 federal RPPNs, all of them located around the National Park of Chapada dos Veadeiros, in the buffer zone area. Chapada dos Veadeiros has been habited for a long time by several landowners and farmers and for this reason, the creation of the RPPN’s represents a viable strategy for the region, which is considered a priority area for conservation project by ONG’s like the Conservation International (CI, the World Wide Fund for Nature (WWF and The Nature Conservancy (TNC by the Ministry of Environment (MMA and the Institute for Biodiversity Conservation Chico Mendes(ICMBIO. The article demonstrates that the private reserves can and should be an important alternative for the implementation of a land planning developed in partnership with the local community. In this review, it was investigated the contribution of the private reserves in the Chapada dos Veadeiros for the local conservation biodiversity and its implementation process.

  4. First Pb-Pb dating results from carbonado diamonds from Chapada Diamantina (BA) and Jequitinhonha River (MG), Espinhaco Range

    International Nuclear Information System (INIS)

    Chaves, Mario Luiz de Sa Carneiro; Sano, Yuji; Chambel, Luis

    2005-01-01

    Most carbonados found in Brazil occur along the Espinhaco Range, associated to conglomeratic rocks of the Espinhaco Supergroup. This paper presents Pb-Pb radiometric ages on mineral inclusions (quartz, rutile and clay) and matrix of carbonados from the Andarai and Jequitinhonha River areas. Even with a large experimental error, the results obtained of 3,8±1,8Ga and 3,3±0,7 Ga respectively, are of regional geologic interest. The minimum carbonado formation age (ca.2,5 Ga) is older than the Espinhaco Supergroup deposition age (≅ 1,7 Ga). Other evidences suggest that this minimum age corresponds to the seed aggregation phase; the crustal inclusions being aggregated in an environment rich in high-energy radioactive particles. (author)

  5. A variação de preposições com verbo ir de movimento em comunidades rurais do semiárido baiano A variação de preposições com verbo ir de movimento em comunidades rurais do semiárido baiano

    OpenAIRE

    Hilmara Moura de JESUS

    2012-01-01

    This article consists in the analysis of variable regency of the verb ir concerning movement in the dialect from communities of Matinha, district of Feira de Santana, Piabas, located in the city of Caem, a former district of Jacobina, Barra / Bananal and MatoGrosso, in ChapadaDiamantina, Casinhas, Tapera e Lagoa do Inácio, in Jeremoabo. For the development of research, we used a sample drawn from 72 informants who make up the corpus of the project “A Língua Portuguesa no ...

  6. Biologia da polinização de Paliavana tenuiflora (Gesneriaceae: Sinningeae) no nordeste do Brasil

    OpenAIRE

    Ferreira, Patrícia Alves; Viana, Blandina Felipe

    2010-01-01

    In this study the floral biology, breeding system, visitors and pollinators of Paliavana tenuiflora were analyzed in campos rupestres in the Chapada Diamantina, Mucugê, Bahia, Brazil. Paliavana tenuiflora is a shrub with blue-violet, bell-shaped flowers, with anthesis at 11:00 h; the flowers last about six days. Large amounts of nectar are produced (volume average 15.5µL, concentration 22.7% and sugar content 5.0 mg mL-1). The amount of nectar is not related to the time of day, but concentrat...

  7. Dispersão de sementes de Melocactus glaucescens e M. paucispinus (Cactaceae, no Município de Morro do Chapéu, Chapada Diamantina - BA Dispersion of Melocactus glaucescens and M. paucispinus (Cactaceae in the municipality of Morro do Chapéu, Chapada Diamantina - BA

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    Rosineide Braz Santos Fonseca

    2012-06-01

    Full Text Available Objetivou-se identificar os dispersores de duas espécies de Melocactus, verificar o padrão de liberação dos frutos, correlacionando-o com a remoção por frugívoros e variação térmica do cefálio, bem como caracterizar a distribuição espacial. Para tanto, foram realizadas observações focais, testes de germinação, registros da emergência, extrusão e remoção de frutos, da temperatura do cefálio, de interações formigas-diásporos e distribuição espacial. Lagartos (2 espécies e formigas (3 espécies foram os dispersores das espécies estudadas. A dormência das sementes não foi quebrada pela passagem pelo trato digestivo dos lagartos. As maiores taxas de remoção dos frutos pelos lagartos ocorreram nas horas centrais do dia, coincidindo ou sendo posterior aos picos de extrusão. As taxas de emergência e extrusão foram mais intensas pela manhã, o que aumentou as chances de remoção dos frutos no dia da liberação, evitando dissecação e predação. Não houve correlação entre a liberação dos frutos e a variação térmica do cefálio. O desenvolvimento do fruto gera tensão nas fibras do cefálio que promove sua emergência ou expulsão. A expulsão de frutos emergidos pode ser auxiliada pela dilatação das fibras em resposta ao aquecimento, tensão da união das fibras na base e saída de outros frutos. A distribuição espacial dos indivíduos parece ser influenciada pelo comportamento dos dispersores.Objectives: identify the dispersers of two species of Melocactus; verify their patterns of fruit offering and correlate this with removal by frugivores and with temperature variations of the cephalium; and analyze the relationship between the spatial distribution of the Melocactus species and the behavior of their dispersers. Focal observations were made of fruit emergence, extrusion and removal, cephalium temperature, ant-diaspore interactions, and plant spatial distribution. Germination tests were also made. Two lizard and three ant species were dispersers of the two species of Melocactus. Seed dormancy was not broken in the digestive tracts of the lizards. The greatest rates of fruit removal by the lizards occurred during the mid hours of the day, coinciding with or following the extrusion peak. Fruit emergence and extrusion rates were highest in the morning, increasing their chances of being taken on the same day, thus avoiding desiccation and predation. No correlation was observed between fruit liberation and thermal variations of the cephalium. Fruit development generates tension within the fiber mass of the cephalium that provokes fruit emergence/expulsion. The expulsion of the fruits may also be aided by the dilation of the cephalium fibers as they warm, tension generated at the cephalium base where the fibers unite, and by the expulsion of other fruits. The spatial distribution of these cacti is influenced by disperser behavior.

  8. Iron-deficiency anemia and associated factors among preschool children in Diamantina, Minas Gerais, Brazil

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    Luciana Neri NOBRE

    Full Text Available ABSTRACT Objective: Study the prevalence of iron depletion and iron-deficiency anemia and their associated factors in preschool children. Methods: Cross-sectional study with five-year old preschool children from a birth cohort of the city of Diamantina, Minas Gerais state, Brazil. Socioeconomic, demographic, and dietary characteristics were obtained through a questionnaire administered to each child mother or guardian. Iron depletion (normal hemoglobin and low serum ferritin levels and iron-deficiency anemia (hemoglobin level than 11g/dL were detected after collecting 5mL of venous blood of preschool children. Poisson regression was used to identify the factors associated with iron depletion and iron-deficiency anemia. Results: A total of 228 preschool were evaluated, corresponding to 97.4% of the children from a cohort study followed-up up to the end of their first year of life. Iron depletion and iron-deficiency anemia were detected, respectively, in 15.9% and 18.9% of the preschool children evaluated. Iron depletion was not associated with any variable studied, while low maternal education level was associated with iron-deficiency anemia (PR=1.83; P=0.03. Conclusion: Iron-deficiency anemia is considered as a mild public health problem among 5-year old children in the city of Diamantina, Minas Gerais. Higher maternal education level was a protective factor against this deficiency, and therefore it is as an important marker for the occurrence of iron-deficiency anemia in the population studied.

  9. Gafanhotos (Orthoptera, Acridoidea em áreas de cerrados e lavouras na Chapada dos Parecis, Estado de Mato Grosso, Brasil Grasshoppers (Orthoptera, Acridoidea in native savanna and crop areas in Chapada dos Parecis, Mato Grosso State, Brazil

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    Wanderlei Dias Guerra

    2012-06-01

    Full Text Available Gafanhotos (Orthoptera, Acridoidea em áreas de cerrados e lavouras na Chapada dos Parecis, Estado de Mato Grosso, Brasil. Foi determinada a composição e abundância de espécies de gafanhotos usando amostragem com rede entomológica durante 3 anos de estudo na Chapada dos Parecis, estado de Mato Grosso. O levantamento foi feito em áreas de lavouras e com vegetação ainda nativa (cerrados com, respectivamente, 56 e 59 locais inventariados em cada ambiente. Foram coletados 3.031 indivíduos de gafanhotos de 64 espécies distribuídas entre as famílias e subfamílias: Acrididae (49: Gomphocerinae (21, Ommatolampinae (10, Melanoplinae (6, Acridinae (4 Leptysminae (3, Copiocerinae (3, Proctolabinae (1 e Cyrtacanthacridinae (1; Romaleidae (1: Romaleinae (13 e Ommexechidae (1: Ommexechinae (2, além de 1550 ninfas. A diversidade de espécies foi maior no cerrado (61 do que nas lavouras (16, ocorrendo o inverso com relação à abundância onde as espécies Baeacris punctulatus (Thunberg, 1824 e Orphulella punctata (De Geer, 1773 predominaram representando 49,5% do total de indivíduos coletados em toda a Chapada dos Parecis e, juntas, somam 78,8% da abundância registrada nas áreas de lavouras e tem potencial de se tornarem pragas.Grasshoppers (Orthoptera, Acridoidea in native savanna and crop areas in Chapada dos Parecis, Mato Grosso State, Brazil. We determined the composition and abundance of grasshoppers using sweep net sampling during three years at the Parecis Plateau, State of Mato Grosso, Brazil. The survey was done in areas with crops and native vegetation (savanna with, respectively, 56 and 59 sites available in each environment. 3.031 individuals of grasshoppers were collected from 64 species distributed among the following families and subfamilies: Acrididae (49: Gomphocerinae (21, Ommatolampinae (10, Melanoplinae (6, Acridinae (4 Leptysminae (3, Copiocerinae (3, Proctolabinae (1 and Cyrtacanthacridinae (1; Romaleidae (1: Romaleinae

  10. Ecological aspects of Rhodnius nasutus Stål, 1859 (Hemiptera: Reduviidae: Triatominae in palms of the Chapada do Araripe in Ceará, Brazil

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    Fernando Braga Stehling Dias

    2008-12-01

    Full Text Available The aim of this work is to present aspects related to the ecology of Rhodnius nasutus Stål, 1859 in palms from Chapada do Araripe in Ceará, Brazil. The following five species of palms were investigated: babaçu (Attalea speciosa, buriti (Mauritia flexuosa, carnaúba (Copernicia prunifera, catolé (Syagrus oleracea and macaúba-barriguda (Acrocomia intumescens. Fifth palms were dissected (10 specimens for each species. The overall infestation index was 86%, with a total of 521 triatomines collected. The Trypanosoma cruzi Chagas, 1909 Index was 16.8% and two insects presented mixed infection with Trypanosoma rangeli Tejera, 1920. A precipitin test showed that R. nasutus from palms of Chapada do Araripe are associated with opossum and bird although other possible bloodmeals were observed. Our results showing a high index of infestation of the palms as well as T. cruzi infection, the association of R. nasutus with the most diverse species of palms and proximity of these palms to houses demonstrate the importance of this area for sylvatic T. cruzi transmission and suggest the need for epidemiological surveillance in the region of the Chapada do Araripe.

  11. Gestão da informação em pequenas e médias empresas: o impacto das tecnologias de inforamção na Auto Comercial Diamantina S.A

    OpenAIRE

    Maria da Graca Eulalio de Souza Bertucci

    2003-01-01

    Esta pesquisa procurou descrever e analisar o impacto das tecnologias de informação e comunicação - TICs - na gestão de pequenas e médias empresas - PME - não metropolitanas. Para isto foi selecionada a Auto Comercial Diamantina S.A, em Diamantina, Minas Gerais, uma concessionária de veículos da rede Volkswagen. Como o estudo pretendeu analisar a relação das TICs na gestão da informação, considerando influências culturais da organização e as caracterírticas das PMEs, foram estabelecidas e est...

  12. Administração ecológica: construindo uma empresa ambiental e socialmente responsável.

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    Marie Agnes Chauvel

    2006-12-01

    Full Text Available O processo de conscientização ambiental, iniciado nos anos 1970, fez que a Administração incluísse a proteção ambiental entre seus objetivos. Novos paradigmas surgiram e conceitos como o de ecologia profunda passaram a ser compreendidos. Surgiram novas formas de negócios, como o ecoturismo. A Venturas & Aventuras, empresa que ingressou nessa atividade, tornou-se pioneira em um destino procurado por pessoas do mundo inteiro, a Chapada Diamantina. Seus fundadores sempre se preocuparam com o meio ambiente, inserindo a comunidade local, constituída de ex-garimpeiros, em suas atividades. Para isso, desenvolveram ações, que resultaram em parceria benéfica para todos os envolvidos — empresa, moradores e clientes —, e que contribui para a preservação do ecossistema da Chapada. Este artigo descreve e analisa essa experiência, mostrando as dificuldades encontradas e as soluções adotadas. A análise mostra que a empresa passou por um processo de aprendizado e transformação, aderindo a vários princípios propostos pela ecologia profunda.

  13. As variáveis ambientais, as estradas regionais e o fluxo das tropas em Diamantina, MG: 1870-1930

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    Marcos Lobato Martins

    2006-06-01

    Full Text Available Este trabalho mapeia as estradas no entorno de Diamantina e analisa as condições de funcionamento das tropas de muares, responsáveis pelo transporte de pessoas e mercadorias no Alto Jequitinhonha na virada do século XIX para o século XX. As variáveis ambientais regionais (topografia, tipos de solos, pluviosidade, temperaturas, características dos rios etc. são apontadas como fatores decisivos, de um lado, para explicar a permanente precariedade das estradas e, de outro lado, para desestimular os investimentos locais em estradas de rodagem e empresas de transporte rodoviário. Dessa forma, o "antigo sistema de circulação" ganhou sobrevida na região até bem adiantado o século XX.This article maps the roads around Diamantina (Minas Gerais and analyses the working conditions of mule trains, responsible for the transportation of people and goods in the Upper Jequitinhonha region on the turn of the 19th to the 20th Century. Regional environmental variables, like topography, types of soil, temperature, rainfall, river characteristics and useful natural resources etc., are seen as decisive factors, on one hand, to explain the road's permanent precariousness and, on the other hand, to discourage local investments in roadways and carrier services. Thus, the ancient circulation system survived in the region well up to the mid-20th century.

  14. ZONEAMENTO AMBIENTAL DO SETOR SUL DO PARQUE NACIONAL

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    Raquel Cardoso de Matos VALE

    2008-12-01

    Full Text Available The elaboration of an environmental zoning is an important tool to subsidize a handling plan and the management of protected areas. In this paper a methodology was established to proceeds environmental zoning having the environmental legislation as criteria to process a digital database GIS-supported (GIS – Geographical Information System. The study area was the south part of the Chapada Diamantina National Park. The database used to produces the environmental zoning map consist of vegetation, soil use, topographic features, hydric resources, scenic beautiful, and tourist, historical and archeological potential areas. The technical support assured by the GIS process were revealed essential to develop this methodology. They provided consistent and expressed overall results, beside the similar point with the landscape reality that was identified in the area of this paper.

  15. Diversidade de insetos e frequência de abelhas visitantes florais de Serjania lethalis na Chapada do Araripe

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    Társio Thiago Lopes Alves

    2014-11-01

    Full Text Available O cipó-uva Serjania lethalis pertence à Sapindacea, grupo de plantas escandentes reconhecidas por sua importância apícola. A espécie é encontrada naturalmente na Chapada do Araripe. O objetivo do trabalho foi estudar a diversidade e frequência dos visitantes florais do cipó-uva nos municípios de Santana do Cariri – CE e Moreilândia – PE nos meses de agosto a novembro entre2009 e 2010. Os visitantes florais foram conhecidos por meio de coletas regulares, usando-se rede entomológica durante o pico de floração. A frequência média de abelhas visitantes florais foi determinada através da contagem simples dos indivíduos, percorrendo por 20 minutos transectos pré-determinados, em sete horários diferentes ao longo dia. Os resultados mostraram indivíduos de Lepidoptera, Diptera, Apidae, Vespidea, Formicidae e Pompilidae visitando as inflorescências do Cipó - Uva, sendo os indivíduos de Apidae mais significativos. Conclui-se que a espécie S. lethalis atrai uma diversidade de visitantes florais, na grande maioria abelhas, especialmente Apis mellifera e Trigona spinipes que a visitam ao longo de todo o dia, indicando uma disponibilidade de recursos por todo esse período, sugerindo que a espécie vegetal possui potencial apícola. A visitação por outras espécies de abelhas nativas e insetos de outros grupos, demonstram a importância de S. lethalis para manutenção de visitantes florais silvestres da Chapada do Araripe.

  16. Evaluation of mercury levels in hair of children resident in artisanal gold mining area in the city of Chapada de Natividade-Tocantins

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Seyna Ueno R., E-mail: seynaueno@gmail.com [Universidade Federal do Tocantins (UFTO), Palmas,TO (Brazil). Coordenação de Medicina; Vasconcellos, Marina B.A.; Catharino, Marília Gabriela M., E-mail: mbvascon@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (CRPQ/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro do Reator de Pesquisa; Quinaglia, Gilson A.; Held, Barbara, E-mail: gquinaglia@sp.gov.br [Companhia Ambiental do Estado de São Paulo (CETESB), São Paulo, SP (Brazil). Setor de Análises Toxicológicas

    2017-07-01

    The objective of the work is to evaluate the mercury exposure of children living in an artisanal gold mining area and in a control area, without mining. A cross-sectional study was conducted with children living in the municipalities of Chapada de Natividade and Porto Nacional, in the State of Tocantins, where hair samples were collected for laboratorial analysis of mercury concentrations, comparing between municipalities, gender, monthly fish consumption, profession of parents and the presence of amalgam in dental restorations. The hair samples were analyzed by the methods of neutron activation analysis and also by means of the DMA (Direct Mercury Analyzer) equipment, in the last case being a partnership with CETESB. There was no evidence of mercury-related diseases in the studied children. The mean concentration of mercury in children in Chapada de Natividade was significantly higher than in Porto Nacional. Children exposed to artisanal gold mining areas have higher concentrations of mercury than children living in non- artisanal gold mining areas. There was no significant relationship between mercury concentrations and gender, monthly fish consumption, parental profession and amalgam presence in dental restorations. The results suggest that the children living in an area exposed to mining experience greater environmental exposure to mercury, regardless of their eating habits or gender. (author)

  17. Evaluation of mercury levels in hair of children resident in artisanal gold mining area in the city of Chapada de Natividade-Tocantins

    International Nuclear Information System (INIS)

    Mendes, Seyna Ueno R.; Vasconcellos, Marina B.A.; Catharino, Marília Gabriela M.; Quinaglia, Gilson A.; Held, Barbara

    2017-01-01

    The objective of the work is to evaluate the mercury exposure of children living in an artisanal gold mining area and in a control area, without mining. A cross-sectional study was conducted with children living in the municipalities of Chapada de Natividade and Porto Nacional, in the State of Tocantins, where hair samples were collected for laboratorial analysis of mercury concentrations, comparing between municipalities, gender, monthly fish consumption, profession of parents and the presence of amalgam in dental restorations. The hair samples were analyzed by the methods of neutron activation analysis and also by means of the DMA (Direct Mercury Analyzer) equipment, in the last case being a partnership with CETESB. There was no evidence of mercury-related diseases in the studied children. The mean concentration of mercury in children in Chapada de Natividade was significantly higher than in Porto Nacional. Children exposed to artisanal gold mining areas have higher concentrations of mercury than children living in non- artisanal gold mining areas. There was no significant relationship between mercury concentrations and gender, monthly fish consumption, parental profession and amalgam presence in dental restorations. The results suggest that the children living in an area exposed to mining experience greater environmental exposure to mercury, regardless of their eating habits or gender. (author)

  18. INNOVATION IN BRAZILIAN TERRITORIAL ASSOCIATION: THE EDUCATIONAL DEVELOPMENT ARRANGEMENTS

    Directory of Open Access Journals (Sweden)

    Eduardo José Grin

    2017-09-01

    Full Text Available The article analyzes the Development Educational Arrangements as ways of territorial association which, in Brasil, since the 2000s, have been one more alternative for municipal consortia. The object of analysis is formed by two cases: the Corredor da Vale (Maranhão and the Chapada Diamantina (Bahia. The research was implemented based on secondary data and a field investigation that interviewed educational municipal managers and representatives from state governments. The selected cases were based on the diverse case methodology that analyzes, controlling variables, different effects of independent variable over dependent variable. The central argument tested is that Educational Arrangements are the independent variables that produce effect on educational territorial governance like dependent variable. We concluded that the larger success in baiano case it was due to factor like regional leadership, social control, path and context of its construction, what didn't happen in the maranhense case.

  19. POSSIBILIDADES DO DESENVOLVIMENTO DO TURISMO ÉTNICO NAS COMUNIDADES QUILOMBOLAS DE DIAMANTINA/MG: OPORTUNIDADES E DESAFIOS

    Directory of Open Access Journals (Sweden)

    Elcione Luciana da Silva

    2016-04-01

    Full Text Available O conceito do turismo étnico vem se desenvolvendo nas últimas décadas e envolve a valorização cultural e possibilidade de promover diversas experiências e inter-relações entre visitantes e comunidades quilombolas. Este artigo versa sobre as comunidades quilombolas (Mata dos Crioulos, Vargem do Inhaí e Quartel de Indaiá – Diamantina/MG, que vêm sofrendo conflitos e pressões de ordem territorial, o que dificulta ainda mais a manutenção da cultura local. O objetivo desta pesquisa é sugerir o desenvolvimento do turismo étnico nas mesmas como forma de desenvolvimento local e valorização do patrimônio cultural material e imaterial. Para alcançar o resultado da pesquisa foram utilizadas referências bibliográficas e documentais. Palavra-chaves: Turismo étnico; comunidades quilombolas; conflitos ambientais e territoriais.

  20. Uso da violência doméstica como prática educativa: conhecendo a realidade em Diamantina – MG/ Brasil = Domestic violence as an educative practice: knowing the reality in Diamantina-MG-Brazil

    Directory of Open Access Journals (Sweden)

    Peruhype, Rarianne Carvalho

    2011-01-01

    Full Text Available O presente artigo objetiva analisar o uso da violência doméstica como prática educativa em Diamantina – MG. Nesse sentido, foi utilizado um questionário aberto para avaliar o uso de disciplina não violenta, violência psicológica e violência física, esta classificada como leve, moderada e grave. A amostra estudada se constituiu de 90 responsáveis por crianças, escolhidas aleatoriamente a partir do universo de 7. 455 crianças matriculadas nas creches, pré-escolas e ensino fundamental, públicos e privados, na sede do município, periferia e também zona rural. Alguns dos resultados mostraram que todos os entrevistados adotam a disciplina não violenta, 95,56% a Violência psicológica e 94,44% a violência física, que, nas formas moderada e grave, é praticada por 74,44% dos entrevistados. O ensino de novas práticas educacionais surge, dessa forma, como uma necessidade urgente

  1. Lutzomyia diamantinensis sp. nov., a new phlebotomine species (Diptera: Psychodidae) from a quartzite cave in Diamantina, state of Minas Gerais, Brazil.

    Science.gov (United States)

    Barata, Ricardo Andrade; Serra e Meira, Paula Cavalcante Lamy; Carvalho, Gustavo Mayr de Lima

    2012-12-01

    A new species of Brazilian phlebotomine sandfly found in Brazil, municipality of Diamantina, state of Minas Gerais, is described based on males and females collected in a quartzite cave. The body of spermathecae is continuous to the individual duct, lanky and tapering at the end, with conical shaped, not striated and presenting the head with dense setae. The male presents gonostyle with four spines and a small subterminal seta and gonocoxite with one group of persistent setae. The paramere is simple with a group of small setae on the dorsal apex. The morphological features of this new species permit its inclusion in the migonei group.

  2. Ethnopharmacological usage of medicinal plants in genitourinary infections by residents of Chapada do Araripe, Crato, Ceará – Brazil - doi: 10.5020/18061230.2012.p278

    Directory of Open Access Journals (Sweden)

    Dayanne Rakelly de Oliveira

    2012-11-01

    Full Text Available Objective: To determine the ethnopharmacological use of plants in the treatment of urogenital tract infections (UTIs by women living in the city of Crato, located in Chapada do Araripe, in the interior of the State of Ceará, Brazil. Methods: A cross-sectional study, with a quantitative approach, performed from September to November, 2010, with 25 residents of Chapada do Araripe, who use and/or recommend plants for the treatment of UTIs. Results: The prevalent characteristics of the informants were: age-group between 56 and 60 years old, married, all of them farmers with a monthly income of minimum wage, and most of them with incomplete schooling. Nine plant species were identified as being used by the population against infection, inflammation and pain. The most common forms of usage are the decoction, cooking and the maceration of leaves and barks. Barbatimão and mallow were the most reported species by informants. Conclusion: Popular medicine is greatly adopted by traditional communities and represents an incalculable cultural wealth which should be preserved and evaluated to assure sustainable development. Information brought out by this research may be useful in further pharmacological studies.

  3. Análise cênica e diversidade visual de paisagens: contribuições para a gestão das trilhas turísticas no Parque Nacional da Chapada dos Veadeiros - GO

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    Romero Gomes Pereira Silva

    2013-01-01

    Full Text Available Scenic analysis and landscape visual diversity: contributions to tourist tracks management in the Parque Nacional Chapada dos Veadeiros. The analysis of landscape scenic quality based on geotechnology reduces the subjectivity problem in visual impact assessments for tourism tracks planning. Employing the viewshed technique we conduced an analysis of landscape quality and diversity for active tracks on Parque Nacional da Chapada dos Veadeiros (Goiás, Brazil, aiming to identifying alternatives for tourism management. The track called “Trilha dos Saltos” shows the greater performance in terms of viewshed size and its scenic quality. The intersection of viewsheds for the two main tracks covers 20.13 km², representing sites that request specific researches to supply subsidies towards the implementation a landscape management policy. The applied technique minimizes the effects of negative environmental impacts, allows an analysis of the best options for visitation purposes and identifies priority areas for environmental management towards the sustainable tourism.

  4. Negócio à moda antiga: tropas de comércio em Diamantina nos meados do século XX

    Directory of Open Access Journals (Sweden)

    Marcos Antônio Lopes

    2011-06-01

    Full Text Available Este artigo analisa uma variedade de aspectos relacionados à atuação das tropas de comércio nas Minas Gerais ao longo dos séculos XIX e XX. Agente central da economia mineira por largo tempo, ressalta-se o conjunto de narrativas dos viajantes estrangeiros sobre o fenômeno do tropeirismo oitocentista, o que ajuda a compreender certos sentidos sociais e culturais implicados no objeto em tela. A partir das memórias de antigos almocreves do Alto Jequitinhonha, procura-se demonstrar, também a notável longevidade alcançada pelas tropas de comércio na região de Diamantina, fenômeno que persistiu até os anos 1950.

  5. Lithostratigraphy of Espinhaco supergroup and Bambini group in the north-west of Bahia state

    International Nuclear Information System (INIS)

    Silva, M.E. da; Karmann, J.; Trompette, R.

    1989-01-01

    The lithostragraphic aspects of the Middle to Upper Proterozoic metasedimentary sequences of the Espinhaco Supergroup and the Bambui Group in northwest Bahia, east-central Brazil, have been studied. The studied area was divided five tectonic domains on the basis of differences in metamorphism and style of folding. This paper proposes the subdivision of Bambui Group into four formations, from bottom to top: Canabravinha, Sao Desiderio, Serra da Mamona, and Riachao das Neves, here correlated, respectively, with Jequitai, Lagoa do Jacare, Serra da Saudade, and Tres Marias formations, all well characterized further south in the State of Minas Gerais. The Espinhaco Supergroup is separable into two metasedimentary units. The younger one, here defined as the Rio Preto Group, was involved in the evolution of the Rio Preto Fold System and contains mainly siliciclastic sediments correlable with the Chapada Diamantina Group. The older unit belongs to the Espinhaco Fold Belt and also is composed mostly of detritic sediments. This sequences in the Santo Onofre Group. (author0 [pt

  6. A ESCRITA DA MEMÓRIA – A CONTRIBUIÇÃO DO IMAGINÁRIO SOCIAL PARA A PRESERVAÇÃO PATRIMONIAL DA CASA DA GLÓRIA (DIAMANTINA-MG (Dossiê: Gestão, Educação e Patrimônio Cultural

    Directory of Open Access Journals (Sweden)

    Isabella Brandão Lara

    2015-06-01

    Full Text Available Resumo: O presente trabalho tem como objetivo demonstrar as diversas versões que as fontes apontam para a história da Casa da Glória, localizada da cidade de Diamantina, Minas Gerais, e símbolo da campanha “Diamantina Patrimônio Cultural da Humanidade”. Pretende-se, com a diversidade de narrativas históricas , ampliar o olhar que a população e os visitantes têm sobre este imóvel e demonstrar como essa multiplicidade de vozes compõem formas coletivas e individuais de se relacionar com o patrimônio material.  A metodologia utilizada para o desenvolvimento desta pesquisa foi a realização de entrevistas, levantamento de fontes documentais e referencial bibliográfico. A principal conclusão deste artigo corrobora com a ideia de que é preciso conhecer para preservar. Quando a comunidade sente-se pertencente a um patrimônio, os próprios moradores atuam como guardião do bem e colaboram para a ampliação de seus processos de conservação e relevância social.Palavras-chave: Casa da Glória, Passadiço, Colégio Nossa Senhora das Dores.Abstract: This study aims to demonstrate the different versions that the sources point to the history of the House of Glory, located in the city of Diamantina, Minas Gerais, and symbol of the campaign "Diamantina Cultural Heritage". It is intended, with the diversity of historical narratives, broaden perspectives that the population and visitors have about this property and demonstrate how this multiplicity of voices make collective and individual ways of relating to the material heritage. The methodology used to develop this research was conducting interviews, survey of documentary sources and bibliographic references. The main conclusion of this article corroborates the idea that you need to know to preserve. When the community feels belonging to an estate, the residents themselves act as guardian of good and collaborate to expand their conservation processes and social relevance.Keywords: House

  7. Temperature profiles from expendable bathythermograph (XBT) casts DIAMANTINA and other Platforms from a World-Wide Distribution in support of the Integrated Global Ocean Services System (IGOSS) and the Pacific Acoustic Research Kaneohe-Alaska (PARKA) from 1966-12-12 to 1974-09-29 (NODC Accession 7500700)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — XBT data were collected from the DIAMANTINA and other Platforms in support of the Integrated Global Ocean Services System (IGOSS) and the Pacific Acoustic Research...

  8. Aves da Chapada dos Guimarães, Mato Grosso, Brasil: uma síntese histórica do conhecimento

    OpenAIRE

    Lopes, Leonardo Esteves; Pinho, João Batista de; Bernardon, Bianca; Oliveira, Fabiano Ficagna de; Bernardon, Giuliano; Ferreira, Luciana Pinheiro; Vasconcelos, Marcelo Ferreira de; Maldonado-Coelho, Marcos; Nóbrega, Paula Fernanda Albonette de; Rubio, Tatiana Colombo

    2009-01-01

    É apresentada uma revisão histórica dos inventários ornitológicos conduzidos na Chapada dos Guimarães, centro-oeste do Brasil. A avifauna da região é caracterizada a partir de uma revisão crítica de todas as listas de espécies produzidas por várias gerações de ornitólogos, espécimes depositados em museus e meticulosos trabalhos de campo. Especial atenção foi dada às publicações de J.A. Allen, baseadas na monumental coleção preparada por H.H. Smith e sua esposa no final do século XIX. A avifau...

  9. Avaliação Quantitativa do Patrimônio Geológico: Aplicação aos Geossítios de São Sebastião, Litoral Norte do Estado de São Paulo

    Directory of Open Access Journals (Sweden)

    Fernanda Coyado Reverte

    2017-04-01

    Full Text Available Este trabalho discute a abordagem metodológica utilizada no inventário e na quantificação do patrimônio geológico do município de São Sebastião, litoral norte de São Paulo. As áreas selecionadas são importantes para a pesquisa científica e correspondem a nove geossítios, sendo seis afloramentos em costões distribuídos pelo município, um arquipélago distante do continente cerca de 50 km e um ponto de interpretação geológica, que funcionará como um mirante. Em virtude da ausência de um método específico para análise quantitativa de zonas costeiras, para o presente trabalho foram adaptadas duas metodologias idealizadas para atender geossítios brasileiros, sendo uma delas específica à Chapada DiamantinaBA. Seguindo um critério de relevância, os resultados obtidos, além de revelar geossítios científicos, com potenciais didáticos e turísticos, orientaram na escolha de ações prioritárias votadas à preservação do referido patrimônio e sugeriram possíveis ações para a atuação futura de instituições públicas e/ou privadas na gestão, conservação e divulgação destas áreas de importante interesse científico, colaborando com o desenvolvimento sustentável da região.

  10. Pollination biology of Paliavana tenuiflora (Gesneriaceae: Sinningeae in Northeastern Brazil Biologia da polinização de Paliavana tenuiflora (Gesneriaceae: Sinningeae no nordeste do Brasil

    Directory of Open Access Journals (Sweden)

    Patrícia Alves Ferreira

    2010-12-01

    Full Text Available In this study the floral biology, breeding system, visitors and pollinators of Paliavana tenuiflora were analyzed in campos rupestres in the Chapada Diamantina, Mucugê, Bahia, Brazil. Paliavana tenuiflora is a shrub with blue-violet, bell-shaped flowers, with anthesis at 11:00 h; the flowers last about six days. Large amounts of nectar are produced (volume average 15.5µL, concentration 22.7% and sugar content 5.0 mg mL-1. The amount of nectar is not related to the time of day, but concentration varied with volume. The species is self-compatible, but fruit set depends on pollinators. Although nectar is available by day and night, flowers of P. tenuiflora fit the bee pollination syndrome, and are actually pollinated by Bombusbrevivillus. However, the hummingbird Phaethornis pretrei can be considered an occasional pollinator, due to its behavior and low frequency of visits. Our results suggest a mixed pollination system, although the importance of P.pretrei as a pollinator remains to be better evaluated.No presente estudo a biologia floral, o sistema reprodutivo, os visitantes e os polinizadores de Paliavana tenuiflora foram analisados em campos rupestres na Chapada Diamantina, Mucugê, Bahia, Brasil. Paliavana tenuiflora é um arbusto com flores campanulares azul-violeta, com antese às 11:00 h, e duração das flores por aproximadamente seis dias. Grandes quantidades de néctar são produzidas (médias de volume 15,5µl, concentração 22,7% e teor de açúcar 5,0 mg µL-1. A produção de néctar não está relacionada com o período do dia, mas a concentração variou com o volume. A espécie é autocompatível, mas a formação de frutos depende de polinizadores. Apesar do néctar estar disponível de dia e de noite, P. tenuiflora se encaixa na síndrome de polinização por abelhas e, de fato, é polinizada por Bombus brevivillus. Entretanto, o beija-flor Phaethornis pretrei pode ser considerado polinizador ocasional, devido a seu

  11. Características físico-químicas de méis da Chapada do Araripe/Santana do Cariri-Ceará - DOI: 10.4025/actascianimsci.v27i1.1264 Physico-chemical characteristics of honey from Chapada do Araripe/Santana do Cariri-Ceará, Brazil - DOI: 10.4025/actascianimsci.v27i1.1264

    Directory of Open Access Journals (Sweden)

    Augusta Carolina de C. Carmello Moreti

    2005-03-01

    Full Text Available Com o objetivo de verificar como se agrupam as amostras de méis, tomando-se por base as características físico-químicas de amostras de méis colhidas na região da Chapada do Araripe, município de Santana do Cariri/Ceará, foram determinados açúcares totais, açúcares redutores, sacarose, umidade, hidroximetilfurfural (HMF, proteína, cinzas, pH, acidez, índice de formol, condutividade elétrica, cor e viscosidade de 21 amostras de méis Apis mellifera L., coletadas entre novembro e dezembro de 2001. Foram identificados ainda os tipos polínicos presentes em cada uma das amostras. Embora as amostras sejam bastante uniformes quanto à origem floral e à latitude e longitude dos locais de coleta, os resultados demonstraram a presença de 12 grupos distintosThis paper was carried out to verify how honey samples, collected from November to December 2001, from the region of Chapada do Araripe, in Santana do Cariri, State of Ceará, Brazil, could be grouped. Twenty-one samples of Apis mellifera honey were studied concerning their total sugars, reducing sugar, sucrose, humidity, Hydroxymethylfurfural (HMF, protein, ashes, pH, acidity, formal index, electric conductivity, color and viscosity. The pollen types occurring in each honey sample were identified as well. Although the samples were fairly uniform regarding the floral origin, the latitude and longitude of the collecting sites, results showed there 12 different groups

  12. A OBESIDADE NA POPULAÇÃO ADULTA DE DIAMANTINA: ORIENTAÇÕES PARA A SAÚDE, CARACTERIZAÇÃO ANTROPOMÉTRICA, BIOQUÍMICA E DE APTIDÃO CARDIORRESPIRATÓRIA

    OpenAIRE

    Bruna Caroline Chaves Garcia; Mariana Aguiar De Matos; Kaio César Pinhal; Marcos Felipe Andrade Oliveira; Rodrigo Teixeira Almeida; Maksilane Eudilane Bento; Vanessa Oliveira Fernandes; Flávio Castro Magalhães; Elizabethe Adriana Esteves; Etel Rocha-Vieira; Fabiano Trigueiro Amorim

    2016-01-01

    Resumo: Este estudo caracterizou indivíduos adultos obesos que participaram de um programa de atividades de extensão composto por orientações nutricionais no município de Diamantina-MG. Foram recrutados 42 indivíduos obesos (7 homens e 35 mulheres, índice de massa corporal [IMC] de 36,5 ± 4,3 kg m-2) com idade entre 19 e 56 anos. Todos os voluntários foram submetidos à avaliação do IMC, circunferência da cintura (CC) e percentual de gordura, glicemia e insulinemia de jejum, teste de tolerânci...

  13. Análise comparativa da florística e fitossociologia da vegetação arbórea do cerrado sensu stricto na Chapada Pratinha, DF - Brasil Comparative analysis of floristics and plant sociology in the "cerrado" arboreal vegetacion sensu stricto in the Chapada Pratinha, DF-Brazil

    Directory of Open Access Journals (Sweden)

    Jeanini Maria Felfili

    1992-12-01

    Full Text Available Foram selecionadas seis áreas de estudo, Estação Ecológica de Aguas Emendadas-DF, Parque Nacional de Brasília-DF, APA Gama-Cabeça do Veado-DF, Silvânia-GO, Paracatu-MG e Patrocínio-MG na Chapada Pratinha (15-20º S e 46-49º W, três delas em unidades de conservação e três fora delas. Em cada área foram amostradas 10 parcelas de 1000 m² (20x50m. Todas as árvores a partir de 5 cm de diâmetro na base do tronco foram medidas e identificadas. A florística e a fitossociologia de cada área foi analisada e estas foram comparadas entre si pelos índices de similaridade de Sørense e de Morisita. No total foram encontradas 139 espécies e 42 famílias sendo que apenas 22 espécies foram comuns a todas as áreas. Leguminosae e Vochysiaceae apresentaram valores de importância elevados em todas as áreas. As densidades por ha variaram de 664 a 1396. Os índices de diversidade de Shannon variaram de 3,11 a 3.56. As similaridades foram altas pelo índices de Sorensen, de 0,5 a 0,7, porém baixas pelo de Morisita quando se comparou as áreas de Paracatu e Patrocínio com as demais áreas. Foi concluído que as diferenças florísticas e principalmente estruturais foram elevadas entre estas duas áreas que são mais distantes e se situam a menores altitudes do que aquelas situadas nas unidades de conservação existentes na chapada sendo sugerida a criação de novas unidades nestes Municípios.Six sites were surveyed at Chapada Pratinha in Brazil (15-20º S e 46-49º W. Three of them were localized in conservation units in the Federal District and the others were in Silvania-GO, Paracatu-MG e Patroci'nio-MG. Ten plots of 1000 m2 (20x50m were sampled in each site. The minimum diameter for measurement of the woody plants was 5 cm at 0.30 m from the ground level. Floristic composition, importance value index and Shannon's diversity index were analyzed for each area. Sørense's and Morisita's similarity indices were used to compare the six sites

  14. Areas of natural occurrence of Melipona scutellaris Latreille, 1811 (Hymenoptera: Apidae in the state of Bahia, Brazil

    Directory of Open Access Journals (Sweden)

    Rogério M.O. Alves

    2012-09-01

    Full Text Available The bee Melipona scutellaris is considered the reared meliponine species with the largest distribution in the North and Northeast regions of Brazil, with records from the state of Rio Grande do Norte down to the state of Bahia. Considering the importance of this species in the generation of income for family agriculture and in the preservation of areas with natural vegetation, this study aimed at providing knowledge on the distribution of natural colonies of M. scutellaris in the state of Bahia. Literature information, interviews with stinglessbee beekeepers, and expeditions were conducted to confirm the natural occurrence of the species. A total of 102 municipalities showed records for M. scutellaris, whose occurrence was observed in areas ranging from sea level up to 1,200-meter height. The occurrence of this species in the state of Bahia is considered to be restricted to municipalities on the coastal area and the Chapada Diamantina with its rainforests. Geographic coordinates, elevation, climate and vegetation data were obtained, which allowed a map to be prepared for the area of occurrence in order to support conservation and management policies for the species.A abelha Melipona scutellaris é considerada a espécie criada de meliponíneo com maior distribuição no norte e nordeste do Brasil, com ocorrência registradas desde o Estado do Grande do Norte até o Estado da Bahia. Considerando a importância desta espécie na geração de renda para agricultura familiar e na manutenção de áreas com vegetação natural, este trabalho teve como objetivo conhecer a distribuição de colônias naturais de M. scutellaris no Estado da Bahia. Informações de literatura, entrevistas com meliponicultores e expedições foram realizadas para confirmar a ocorrência natural da espécie. Um total de 102 municípios apresentou registro de M. scutellaris, cuja ocorrência foi observada em áreas desde o nível do mar até 1.200 metros de altitude. A

  15. Modelo Integrado de Sustentabilidade e Competitividade em Meios de Hospedagem [MISCMH

    Directory of Open Access Journals (Sweden)

    Murilo de Alencar Souza Oliveira

    2015-01-01

    Full Text Available Normal 0 21 false false false PT-BR X-NONE X-NONE RESUMO Este estudo, qualitativo (pesquisa exploratória e de campo, propõe um Modelo Integrado de Sustentabilidade e Competitividade em Meios de Hospedagem [MISCMH], no Brasil. Utilizou a observação direta e entrevistas semiestruturadas com gestores de 15 meios de hospedagem que possuem práticas socioambientais implantadas, localizados nos destinos turísticos de Armação dos Búzios, Rio de Janeiro, Chapada Diamantina, Bahia, e Região das Hortênsias, Rio Grande do Sul. Os resultados apontaram os principais fatores externos (políticas, incentivos e regulações governamentais e os recursos organizacionais (localização e instalações prediais; conscientização dos gestores e funcionários; e, parceiras e relacionamentos construídos, mediante uso da Visão Baseada em Recursos [RBV], que influenciaram a tomada de decisão em sustentabilidade dos gestores. O estudo confirma o pressuposto que sustentou a proposição do Modelo (MISCMH de que este tipo de decisão representa vantagem competitiva no que tange às economias de recursos naturais, à divulgação da marca e à profissionalização da gestão. Sugere-se também maior consideração dos fatores de sustentabilidade na hotelaria, nas políticas governamentais e nos programas de certificação e rotulagem para o turismo brasileiro. Integrated Model of Sustainability and Competitiveness in Lodging Facilities - This study, qualitative (exploratory research and field, proposes an Integrated Model of Sustainability and Competitiveness in Lodging (MISCMH in Brazil. The study used direct observation and semi-structured interviews with managers of 15 Accommodations Establishments that have social and environmental practices deployed, located in tourist destinations of Armação dos Búzios, Rio de Janeiro, Chapada Diamantina, Bahia and Região das Hortênsias, Rio Grande do Sul. The results indicate the main external factors of adherence

  16. Mass spectrometric determination of stability of gaseous BaMoO2, Ba2MoO4, Ba2MoO5, Ba2Mo2O8 molecules

    International Nuclear Information System (INIS)

    Kudin, L.S.; Balduchchi, Dzh.; Dzhil'i, G.; Gvido, M.

    1982-01-01

    During the mass spectrometric investigation of BaCrO 4 evaporation Cr + , Ba + , BaO + main ions are recorded as well as BaMoO 4 + , BaMoO 3 + , BaMoO 2 + , BaMoO + , BaMoO 4 + , Ba 2 MoO 5 + , BaMo 2 O 8 + ions - the products of ionization of three-component (Ba, Mo, M) molecules, forming as a result of substance chemical interaction with the material of an effusion cell (Mo). Heats of formation of BaMoO 2 , Ba 2 MoO 4 , Ba 2 MoO 5 and Ba 2 Mo 2 O 8 molecules which constituted - 577+-70, -1343+-115, -1464+-70, -2393+-90 k J/mol respectively are determined on the base of the analysis of curves of ionisation efficiency and of reaction heats Ba 2 MoO 5 =BaO+BaMoO 4 , ΔH 0 0 =322+-60 kJ/mol Ba 2 Mo 2 O 8 =2BaMoO 4 , ΔH 0 0 =351+-80 kJ/mol calculated with the use of third low of thermodynamics [ru

  17. Plant species visited by the Horned Sungem Heliactin bilophus (Aves, Trochilidae at Chapada dos Veadeiros, during the rainy season

    Directory of Open Access Journals (Sweden)

    Gabriel Baruffaldi Ghiringhello

    2009-12-01

    Full Text Available The feeding habits of the Horned Sungem remain little known. This study aimed to identify the plant species most often visited by H. bilophus with feeding purposes (consumption of nectar during the rainy season at Chapada dos Veadeiros National Park, Goiás. Observations were made during two rainy seasons (January 2006 and February 2008. The methodology consisted of walking through trails within two areas of campo sujo and two areas of campo rupestre. The record of an individual consuming the nectar of a flowering plant was considered to constitute a visit. A total of 296 visits were observed, comprising eight species of shrubs and herbs. The most often visited plant species were Bauhinia tenella (Caesalpinoideae and Vochysia pumila (Vochysiaceae in campo sujo, and Lychnophora ericoides (Asteraceae in campo rupestre. These three species were commonly found at the study sites. In both physiognomies, Heliactin bilophus consumed the nectar of few plant species. The most frequently visited species bore high numbers of flowers.

  18. A OBESIDADE NA POPULAÇÃO ADULTA DE DIAMANTINA: ORIENTAÇÕES PARA A SAÚDE, CARACTERIZAÇÃO ANTROPOMÉTRICA, BIOQUÍMICA E DE APTIDÃO CARDIORRESPIRATÓRIA

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    Bruna Caroline Chaves Garcia

    2016-08-01

    Full Text Available Resumo: Este estudo caracterizou indivíduos adultos obesos que participaram de um programa de atividades de extensão composto por orientações nutricionais no município de Diamantina-MG. Foram recrutados 42 indivíduos obesos (7 homens e 35 mulheres, índice de massa corporal [IMC] de 36,5 ± 4,3 kg m-2 com idade entre 19 e 56 anos. Todos os voluntários foram submetidos à avaliação do IMC, circunferência da cintura (CC e percentual de gordura, glicemia e insulinemia de jejum, teste de tolerância oral à glicose (TTOG triglicérides, colesterol total e frações e aptidão cardiorrespiratória. Dos 42 participantes, onze indivíduos apresentaram resistência à insulina, onze aumento na insulina de jejum (26% e sete (17% apresentaram aumento na glicemia de jejum e/ou alteração no TTOG. Vinte e quatro porcento dos participantes apresentaram concentração de triglicerídeos elevada, 48% apresentaram HDL-colesterol reduzido e noventa e quatro por cento dos participantes apresentaram CC acima do valor recomendado pela Organização Mundial de Saúde. Os participantes do estudo apresentaram um consumo máximo de oxigênio médio menor que 21 ml kg-1 min-1, indicando um baixo condicionamento cardiorrespiratório. Parte dos participantes do estudo (n=10, 23% participaram de uma oficina de orientação nutricional que possibilitou uma ampla discussão sobre a obesidade, seus impactos na saúde, e a necessidade de se adotar hábitos de vida saudáveis. Palavras-chave: Extensão Universitária, Excesso de Peso, Resistência à Insulina, Sedentarismo. Obesity in the adult population of Diamantina city: health guidelines, anthropometric, biochemical and cardiorespiratory fitness characterization Abstract: This study characterized obese adults who participated in an outreach program activity on nutrition education in the city of Diamantina, Minas Gerais State, Brazil. 42 obese subjects, aged between 19 and 56 years old, were recruited (7 men and

  19. “Smart fish that can see at a distance”: Traditional ichthyological knowledge in the Chapada Diamantina region, Bahia

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    Eliane Maria de Souza Nogueira

    2008-09-01

    Full Text Available This paper examines the traditional ichthyological knowledge of a community of fishermen that live in the Marimbus-Iraquara environmental protection area (Bahia, Brazil. Data were collected using open and semi-structured interviews and field observation. Also, zoological materials were collected. Knowledge about the behavior of 21 fish species is reported. The ethological phenomena perceived by the fishermen were divided into 17 ethological categories related to reproduction, flight behavior, predation, social behavior, or response to artificial stimuli. The results of the study indicate the existence of a broad local ecological knowledge about species and ecosystems, particularly in relation to fish species.

  20. Pollen grain morphology of Fabaceae in the Special Protection Area (SPA) Pau-de-Fruta, Diamantina, Minas Gerais, Brazil.

    Science.gov (United States)

    Luz, Cynthia F P da; Maki, Erica S; Horák-Terra, Ingrid; Vidal-Torrado, Pablo; Mendonça Filho, Carlos Victor

    2013-01-01

    The presented paper considered the pollen morphology of thirteen species belonging to seven genera of the Fabaceae family occurring in the Pau-de-Fruta Special Protection Area (SPA), Diamantina, state of Minas Gerais, Brazil. The pollen grains of six species of Chamaecrista [C. cathartica (Mart.) H.S. Irwin & Barneby, C. debilis Vogel, C. flexuosa (L.) Greene, C. hedysaroides (Vogel) H.S. Irwin & Barneby, C. glandulosa (L.) Greene, and C. papillata H.S. Irwin & Barneby] have a similar morphology, characterized by three long colporated apertures with a central constriction. The species share specific morphological features regarding pollen size, endoaperture type (circular, lalongate or lolongate) and SEM ornamentation patterns of the exine (rugulate with perforations or perforate). Andira fraxinifolia Benth., Dalbergia miscolobium Benth, Galactia martii DC, Periandra mediterranea (Vell.) Taub., Senna rugosa (G.Don) H.S. Irwin & Barneby and Zornia diphylla (L.) Pers showed different pollen types in small to large size; oblate spheroidal to prolate form; colpus or colporus apertures; circular, lalongate or lolongate endoapertures and distinctive SEM ornamentation patterns of the exine (perforate, microreticulate, reticulate or rugulate with perforations). Only Stryphnodendron adstringens (Mart.) Coville presents polyads. The pollen morphology variation of these species allowed the Fabaceae family to be characterized as eurypalynous in the SPA Pau-de-Fruta.

  1. Areas of natural occurrence of Melipona scutellaris Latreille, 1811 (Hymenoptera: Apidae) in the state of Bahia, Brazil.

    Science.gov (United States)

    Alves, Rogério M O; Carvalho, Carlos A L; Souza, Bruno A; Santos, Wyratan S

    2012-09-01

    The bee Melipona scutellaris is considered the reared meliponine species with the largest distribution in the North and Northeast regions of Brazil, with records from the state of Rio Grande do Norte down to the state of Bahia. Considering the importance of this species in the generation of income for family agriculture and in the preservation of areas with natural vegetation, this study aimed at providing knowledge on the distribution of natural colonies of M. scutellaris in the state of Bahia. Literature information, interviews with stinglessbee beekeepers, and expeditions were conducted to confirm the natural occurrence of the species. A total of 102 municipalities showed records for M. scutellaris, whose occurrence was observed in areas ranging from sea level up to 1,200-meter height. The occurrence of this species in the state of Bahia is considered to be restricted to municipalities on the coastal area and the Chapada Diamantina with its rainforests. Geographic coordinates, elevation, climate and vegetation data were obtained, which allowed a map to be prepared for the area of occurrence in order to support conservation and management policies for the species.

  2. Spontaneous behavior of basal Copionodontinae cave catfishes from Brazil (Teleostei, Siluriformes, Trichomycteridae

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    Bianca Rantin

    2015-08-01

    Full Text Available Cave animals are particularly interesting due to their behavioral specializations, resultant from evolution in isolation. We present data from a spontaneous behavior study (spatial distribution and preference for microhabitats of two troglobitic catfish from Brazil: Glaphyropoma spinosum and a new species of Copionodon. We compared the data with those obtained of a sympatric epigean species, Copionodon pecten. These Trichomycteridae species belong to a basal and apparently monophyletic subfamily – Copionodontinae, endemic to Chapada Diamantina, central Bahia state, eastern Brazil. We observed the fishes in natural and laboratory conditions through ad libitum and focal animal methods. Each spatial behavioral category (hidden, bottom, midwater, surface and wall swimming and stationary in the bottom was timed individually, with a sample of 12 specimens per species. Unlike most troglobitic fishes, cave copionodontines tested herein did not extend exploratory behavior to midwater, with benthonic and thigmotactic-related exploratory behavior. This behavior is possibly related to its feeding behavior specializations, strong territorialism and photophobic behavior. The epigean Copionodon species is also benthonic. The spatial behavior of the cave Copionodontinae could be interpreted as a retained and plesiomorphic character-state in relation to other trichomycterid catfishes.

  3. Evaluation of heat focuss and Monte Alegre formula in Chapada dos Guimarães National park

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    Arlindo de Paula Machado Neto

    2017-12-01

    Full Text Available The present study aimed to analyze the behavior of the Monte Alegre Formula (MAF and to quantify the heat focus detected by reference satellites, comparing them with the fires that occurred in Chapada dos Guimarães National Park from 2007 to 2015. Heat analysis was performed using images from AQUA, TERRA and NOAA satellites, whose daily data of detected foci were used to compose the time series over the years, allowing the analysis of trends in the numbers of foci for the park. The data were acquired in the platform of the National Institute of Space Research, in the historical data base of the National Institute of Meteorology and by to the manager of the park. In most years there was an overestimation of the number of heat sources in relation to the number of fire occurrences. The TERRA satellite presented values were closer to the number of fire records in the park. It was observed that 87.69% of the fires were validated in relation to MAF, where 60% belonged to very high hazard class and 27.69% were classified in the high hazard class, demonstrating the effectiveness of MAF in relation to records of fires occurring in the park.

  4. Refinement of crystal structures of CaHCl, SrHCl, BaHCl, BaHBr, and BaHI

    International Nuclear Information System (INIS)

    Beck, H.P.; Limmer, A.

    1983-01-01

    The structures of CaHCl, SrHCl, BaHBr, BaHCl, and BaHI have been refined using single crystal data. The comparison of the parameters with the corresponding data of isotypic fluorohalide compounds gives a valuable insight into the bonding interactions in this structure type. (author)

  5. Refinement of crystal structures of CaHCl, SrHCl, BaHCl, BaHBr, and BaHI

    Energy Technology Data Exchange (ETDEWEB)

    Beck, H.P.; Limmer, A. (Erlangen-Nuernberg Univ., Erlangen (Germany, F.R.). Inst. fuer Anorganische Chemie)

    1983-07-01

    The structures of CaHCl, SrHCl, BaHBr, BaHCl, and BaHI have been refined using single crystal data. The comparison of the parameters with the corresponding data of isotypic fluorohalide compounds gives a valuable insight into the bonding interactions in this structure type.

  6. Phase equilibria in the BaUO3-BaZrO3-BaMoO3 system

    International Nuclear Information System (INIS)

    Kurosaki, Ken; Yamanaka, Shinsuke; Matsuda, Tetsushi; Uno, Masayoshi; Yamamoto, Kazuya; Namekawa, Takashi

    2002-01-01

    The phase equilibria in the pseudo-ternary BaUO 3 -BaZrO 3 -BaMoO 3 system were studied to understand the thermochemical properties of the perovskite type gray oxide phase in high burnup MOX fuel. Thermodynamic equilibrium calculation for the system was performed by using a Chem Sage program under the various oxygen potentials. Solid solutions existing in the system were treated by an ideal solution model. The present calculation results well agreed with the previous reported post irradiation examination results, showing that BaMoO 3 was scarcely included in the gray oxide phase. (author)

  7. Epidemia de dengue em Ipupiara e Prado, Bahia. Inquérito soro-epidemiológico Outbreak of dengue in Ipupiara and Prado, Bahia State. Seroepidemiologic survey

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    Pedro Fernando da Costa Vasconcelos

    2000-02-01

    Full Text Available No Brasil, os inquéritos sorológicos têm assinalado taxa de infecção pelo vírus do dengue de 25% a 56%, porém esses estudos foram realizados em populações de cidades de médio ou grande porte. No presente estudo, são descritas duas epidemias de febre clássica de dengue (DEN no Estado da Bahia. A primeira, ocorrida em 1987 e causada pelo sorotipo DEN-1 em Ipupiara e, a segunda, causada pelo DEN-2, em Prado e que ocorreu em 1995. O diagnóstico laboratorial foi realizado utilizando o teste de inibição da hemaglutinação (IH. Em 1995, foram coletadas 461 amostras sorológicas de uma população de 3.868 habitantes em Ipupiara (região da Chapada Diamantina e 228 de um total de 9.126 habitantes em Prado (Litoral Extremo Sul. A soro-positividade das amostras foi de 11,9% (55/461 em Ipupiara e 17,5% (40/228 em Prado. Não houve diferença, estatisticamente significante, quanto a idade e o gênero entre os indivíduos soro-positivos e negativos das duas cidades estudadas. Entretanto, em Ipupiara os soro-positivos (15,9% vs. 9,3% relataram, mais freqüentemente (p Serologic studies in Brazil have indicated a 25% to 56% prevalence of dengue virus infections. However, these studies were carried out in populations of middle-sized and larger cities. The present study describes two epidemics of classic dengue fever in two small cities in the State of Bahia. The first occurred in 1987, in Ipupiara and was caused by dengue serotype-1 (DEN-1, the second occurred in 1995, in Prado and was caused by dengue serotype-2 (DEN-2. The laboratory diagnosis was made by the hemagglutination-inhibitation test. 461 serum samples were collected in 1995 in Ipupiara (district of Chapada Diamantina out of a population of 3,868 and 228 samples out of a total of 9,126 inhabitants of Prado (in the Southernmost coastal region. The seropositivity of the samples was 11.9% (55/461 in Ipupiara and 17.5% (40/228 in Prado. These were no statistically significant differences

  8. Syntheses, crystal structure, and electronic properties of the five ABaMQ{sub 4} compounds RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Mesbah, Adel [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); ICSM, UMR 5257 CEA / CNRS / UM / ENSCM, Site de Marcoule-Bâtiment 426, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); Prakash, Jai [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); Rocca, Dario; Lebègue, Sébastien [Laboratoire de Cristallographie, Résonance Magnétique, et Modélisations CRM2 (UMR UHP-CNRS 7036), Faculté des Sciences et Techniques, Université de Lorraine, BP 70239, Boulevard des Aiguillettes, 54506 Vandoeuvre-lès-Nancy Cedex (France); Beard, Jessica C.; Lewis, Benjamin A. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); Ibers, James A., E-mail: ibers@chem.northwestern.edu [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States)

    2016-01-15

    Five new compounds belonging to the ABaMQ{sub 4} family were synthesized by solid-state chemistry at 1123 K. The compounds RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4} are isostructural and have the TlEuPS{sub 4} structure type. They crystallize in space group D{sup 16}{sub 2h} – Pnma of the orthorhombic system. Their structure consists isolated MQ{sub 4} tetrahedra separated by A and Ba atoms to form a salt-like structure. Density Functional Theory (DFT) calculations of the electronic structures with the use of the HSE functional suggest that the compounds are semiconductors with calculated band gaps of 3.3 eV (RbBaPS{sub 4}), 3.4 eV (CsBaPS{sub 4}), 2.3 eV (CsBaVS{sub 4}), and 1.6 eV (RbBaVSe{sub 4}). - Graphical abstract: General view of the ABaMQ{sub 4} structure down the a axis. - Highlights: • Five new ABaMQ{sub 4} compounds were synthesized by solid-state chemistry at 1123 K. • RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4} have the TlEuPS{sub 4} structure type. • The compounds are semiconductors with calculated band gaps ranging from 1.6 to 3.4 eV.

  9. CONTEXTO GEOMORFOLÓGICO DE OCORRÊNCIA DE CAVIDADES EM QUARTZITO NA REGIÃO SUDESTE DE DIAMANTINA/MG

    Directory of Open Access Journals (Sweden)

    Fernanda Souza

    2014-12-01

    Full Text Available O presente trabalho tem como objetivo interpretar o contexto geográfico associado à ocorrência de cavidades nos quartzitos da região sudeste de Diamantina/MG - Serra do Espinhaço Meridional. O procedimento metodológico foi composto por revisão bibliográfica; levantamento cartográfico; trabalhos de campo; topografia das cavidades; levantamento das linhas estruturais na área externa e no interior das cavidades; petrografia; coleta, laminação e análise química qualitativa de depósitos químicos e interpretação do contexto geográfico de inserção das cavidades. Os resultados obtidos demonstram que a ocorrência de feições cársticas na área de estudo pode estar relacionada a um conjunto de fatores. Assim, a presença de poliminerais, como mica e feldspato; diferentes camadas estratigráficas da Formação Sopa-Brumadinho (quartzitos monomíticos e conglomerados; os lineamentos estruturais e as características geomorfológicas locais são fatores que contribuem para a ocorrência de cavidades na região. A hipótese de formação das cavidades indica a probabilidade de ocorrência de dissolução, produção de materiais inconsolidados, lixiviação, remobilização dos grãos alterados e ampliação dos condutos através de abatimentos.

  10. The influence of El Niño and edge effects on the reproductive phenology and floral visitors of Eschweilera tetrapetala Mori (Lecythidaceae, an endemic species of the Atlantic Forest of northeastern Brazil

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    Isiara Silva Menezes

    2017-10-01

    Full Text Available ABSTRACT We compared the reproductive phenology and floral visitors of Eschweilera tetrapetala growing along the edge and in the interior of a submontane forest in the Chapada Diamantina mountains, Bahia State, Brazil. We sought to determine if there were inter-annual differences in intensity and seasonality associated with environmental conditions, and if there were differences in floral visitors between the two environmental contexts. Phenological observations were performed for three years, and included the occurrence of an El Niño event. We applied circular statistics to detect seasonal trends, performed cross correlations between phenophases and climate, Kruskal-Wallis and Wilcoxon signed-rank tests for inter-annual variation, and the Wilcoxon-Mann-Whitney test for edge-interior differences in the species richness of floral visitors. We observed inter-annual variations in the intensity and seasonality of flower production that accompanied variations in rainfall, possibly associated with El Niño events. Floral visitor richness differed between the forest edge and interior, with seven species recorded for the interior and only one for the edge. Reduced fruit set was also observed at the forest edge. This study contributes to our understanding of the influence of El Niño and edge effects on the reproductive phenologies of tropical plants.

  11. Subnitride chemistry: A first-principles study of the NaBa3N, Na5Ba3N, and Na16Ba6N phases

    International Nuclear Information System (INIS)

    Oliva, Josep M.

    2005-01-01

    An ab initio study on the electronic structure of the subnitrides NaBa 3 N, Na 5 Ba 3 N, and Na 16 Ba 6 N is performed for the first time. The NaBa 3 N and Na 5 Ba 3 N phases consist of infinite 1 ∞ [NBa 6/2 ] strands composed of face-sharing NBa 6 octahedra surrounded by a 'sea' of sodium atoms. The Na 16 Ba 6 N phase consist of discrete [NBa 6 ] octahedra arranged in a body-cubic fashion, surrounded by a 'sea' of sodium atoms. Our calculations suggest that the title subnitrides are metals. Analysis of the electronic structure shows partial interaction of N(2s) with Ba(5p) electrons in the lower energy region for NaBa 3 N and Na 5 Ba 3 N. However, no dispersion is observed for the N(2s) and Ba(5p) bands in the cubic phase Na 16 Ba 6 N. The metallic band below the Fermi level shows a strong mixing of N(2p), Ba(6s), Ba(5d), Ba(6p), Na(3s) and Na(3p) orbitals. The metallic character in these nitrides stems from delocalized electrons corresponding to hybridized 5d l 6s m 6p n barium orbitals which interact with hybridized 3s n 3p m sodium orbitals. Analysis of the electron density and electronic structure in these nitrides shows two different regions: a metallic matrix corresponding to the sodium atoms and the regions around them and heteropolar bonding between nitrogen and barium within the infinite 1 ∞ [NBa 6/2 ] strands of the NaBa 3 N and Na 5 Ba 3 N phases, and within the isolated [NBa 6 ] octahedra of the Na 16 Ba 6 N phase. The nitrogen atoms inside the strands and octahedra are negatively charged, the anionic character of nitrogens being larger in the isolated octahedra of the cubic phase Na 16 Ba 6 N, due to the lack of electron delocalization along one direction as opposed to the other phases. The sodium and barium atoms appear to be slightly negatively and positively charged, the latter to a larger extent. From the computed Ba-N overlap populations as well as the analysis of the contour maps of differences between total density and superposition of

  12. Study of testacean assemblages (Protozoa: Rhizopoda in touristic waterfall regions of Chapada dos Guimarães National Park, Mato Grosso State, Brazil - doi: 10.4025/actascibiolsci.v32i4.7456 Study of testacean assemblages (Protozoa: Rhizopoda in touristic waterfall regions of Chapada dos Guimarães National Park, Mato Grosso State, Brazil - doi: 10.4025/actascibiolsci.v32i4.7456

    Directory of Open Access Journals (Sweden)

    Márcia Teixeira de Oliveira

    2010-11-01

    Full Text Available An evaluation was made of the effect of temporal variations on an assembly of Testaceae in several water bodies located in Chapada dos Guimarães National Park. A sampling point was selected at each study site, where 4 samplings were collected per season, considering the climatic conditions of the dry and rainy periods. The findings revealed 80 infrageneric taxa, 05 families and 12 genera. Pearson’s correlation between the second axis of the DCA and the first axis of the PCA was significant, even after applying Bonferroni’s correction for multiple significance tests (r = 0.683; p = 0.014. Thus, the temporal variation of the limnological data, which showed higher values of turbidity, total solids, color and temperature for the rainy period and higher concentrations of nitrogen and phosphorus during the dry season, was significantly correlated with the biotic data. The second axis of the PCA indicated that the variables remained unchanged during the seasonal periods under study.An evaluation was made of the effect of temporal variations on an assembly of Testaceae in several water bodies located in Chapada dos Guimarães National Park. A sampling point was selected at each study site, where 4 samplings were collected per season, considering the climatic conditions of the dry and rainy periods. The findings revealed 80 infrageneric taxa, 05 families and 12 genera. Pearson’s correlation between the second axis of the DCA and the first axis of the PCA was significant, even after applying Bonferroni’s correction for multiple significance tests (r = 0.683; p = 0.014. Thus, the temporal variation of the limnological data, which showed higher values of turbidity, total solids, color and temperature for the rainy period and higher concentrations of nitrogen and phosphorus during the dry season, was significantly correlated with the biotic data. The second axis of the PCA indicated that the variables remained unchanged during the seasonal periods

  13. Syntheses and crystal structures of BaAgTbS{sub 3}, BaCuGdTe{sub 3}, BaCuTbTe{sub 3}, BaAgTbTe{sub 3}, and CsAgUTe{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, Jai; Beard, Jessica C.; Ibers, James A. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); Mesbah, Adel [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); ICSM-UMR 5257 CNRS/CEA/UM2/ENSCM, Bat 426, BP 17171, 30207 Bagnols/Ceze (France)

    2015-06-15

    Five new quaternary chalcogenides of the 1113 family, namely BaAgTbS{sub 3}, BaCuGdTe{sub 3}, BaCuTbTe{sub 3}, BaAgTbTe{sub 3}, and CsAgUTe{sub 3}, were synthesized by the reactions of the elements at 1173-1273 K. For CsAgUTe{sub 3} CsCl flux was used. Their crystal structures were determined by single-crystal X-ray diffraction studies. The sulfide BaAgTbS{sub 3} crystallizes in the BaAgErS{sub 3} structure type in the monoclinic space group C{sup 3},{sub 2h}-C2/m, whereas the tellurides BaCuGdTe{sub 3}, BaCuTbTe{sub 3}, BaAgTbTe{sub 3}, and CsAgUTe{sub 3} crystallize in the KCuZrS{sub 3} structure type in the orthorhombic space group D{sup 1},{sub 2}{sup 7},{sub h}-Cmcm. The BaAgTbS{sub 3} structure consists of edge-sharing [TbS{sub 6}{sup 9-}] octahedra and [AgS{sub 5}{sup 9-}] trigonal pyramids. The connectivity of these polyhedra creates channels that are occupied by Ba atoms. The telluride structure features {sup 2}{sub ∞}[MLnTe{sub 3}{sup 2-}] layers for BaCuGdTe{sub 3}, BaCuTbTe{sub 3}, BaAgTbTe{sub 3}, and {sup 2}{sub ∞}[AgUTe{sub 3}{sup 1-}] layers for CsAgUTe{sub 3}. These layers comprise [MTe{sub 4}] tetrahedra and [LnTe{sub 6}] or [UTe{sub 6}] octahedra. Ba or Cs atoms separate these layers. As there are no short Q..Q (Q = S or Te) interactions these compounds achieve charge balance as Ba{sup 2+}M{sup +}Ln{sup 3+}(Q{sup 2-}){sub 3} (Q = S and Te) and Cs{sup +}Ag{sup +}U{sup 4+}(Te{sup 2-}){sub 3}. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Pedochronology and development of peat bog in the environmental protection area pau-de-fruta - Diamantina, Brazil

    Directory of Open Access Journals (Sweden)

    José Ricardo da Rocha Campos

    2010-12-01

    Full Text Available In the region of the Serra do Espinhaço Meridional, peat bog is formed in hydromorphic environments developed in sunken areas on the plain surfaces with vegetation adapted to hydromorphic conditions, favoring the accumulation and preservation of organic matter. This pedoenvironment is developed on the regionally predominant quartzite rocks. Peat bog in the Environmental Protection Area - APA Pau-de-Fruta, located in the watershed of Córrego das Pedras, Diamantina,Brazil, was mapped and three representative profiles were morphologically characterized and sampled for physical, chemical and microbiological analyses. The organic matter was fractionated into fulvic acid (FA, humic acids (HA and humin (H. Two profiles were sampled to determine the radiocarbon age and δ13C. The structural organization of the three profiles is homogeneous. The first two layers consist of fibric, the two subsequent of hemic and the four deepest of sapric peat, showing that organic matter decomposition advances with depth and that the influence of mineral materials in deeper layers is greater. Physical properties were homogeneous in the profiles, but varied in the sampled layers. Chemical properties were similar in the layers, but the Ca content, sum of bases and base saturation differed between profiles. Contents of H predominated in the more soluble organic matter fractions and were accumulated at a higher rate in the surface and deeper layers, while HA levels were higher in the intermediate and FA in the deeper layers. Microbial activity did not vary among profiles and was highest in the surface layers, decreasing with depth. From the results of radiocarbon dating and isotope analysis, it was inferred that bog formation began about 20 thousand years ago and that the vegetation of the area had not changed significantly since then.

  15. The advertisement call of Bokermannohyla flavopicta Leite, Pezzuti & Garcia, 2012 (Anura: Hylidae) from the mountains of Chapada Diamantina, Bahia, Brazil.

    Science.gov (United States)

    Rocha, Pedro Carvalho; Thompson, Julia Resende; Leite, Felipe Sá Fortes; Garcia, Paulo Christiano De Anchietta

    2016-01-07

    Bokermannohyla Faivovich, Haddad, Garcia, Frost, Campbell & Wheeler (2005) is a Brazilian treefrog genus currently composed of 32 species (Brandão et al. 2012; Leite et al. 2012; Frost 2015). The genus comprehends four, putatively monophyletic, species groups: B. circumdata, B. claresignata, B. martinsi, and B. pseudopseudis (sensu Faivovich et al. 2005). The B. pseudopseudis group includes nine species: B. alvarengai (Bokermann 1956), B. flavopicta Leite et al. 2012, B. ibitiguara (Cardoso 1983), B. itapoty Lugli & Haddad 2006a, B. oxente Lugli & Haddad 2006b, B. pseudopseudis (Miranda-Ribeiro 1937), B. sagarana Leite et al. 2011, B. sapiranga Brandão et al. 2012, and B. saxicola (Bokermann 1964).

  16. Estratégias fenológicas de Senna cana (Nees & Mart. H.S. Irwin & Barneby (Fabaceae: Caesalpinioideae como mecanismo eficiente para atração de polinizadores Phenological strategies of Senna cana (Nees & Mart. H.S. Irwin & Barneby (Fabaceae: Caesalpinioideae as efficient mechanisms for attracting pollinators

    Directory of Open Access Journals (Sweden)

    Isys Mascarenhas Souza

    2012-06-01

    Full Text Available Este trabalho verificou a importância das estratégias fenológicas de Senna cana na atração de visitantes e polinizadores na mata ciliar do rio Lençóis, Chapada Diamantina, Bahia. As observações fenológicas foliares (queda foliar e brotamento e reprodutivas (botão, flor, fruto imaturo e fruto maduro foram mensais (18 meses em 10 indivíduos marcados. Para a biologia floral observou-se: antese, duração das flores, receptividade estigmática, viabilidade polínica, presença de osmóforos e pigmentos que refletem raios ultravioleta. Foram realizados testes de autopolinização manual, espontânea e polinização cruzada. Os visitantes e polinizadores foram determinados observando-se: horário, duração, freqüência das visitas e comportamento de forrageio. Senna cana é uma espécie perenifólia episódica, com eventos reprodutivos sazonais e altamente sincrônicos (floração intermediária no período chuvoso e frutificação longa no período seco. Tais características na floração, somadas à síndrome de melitofilia, configuram importantes estratégias para atração de visitantes florais, dentre os quais Xylocopa frontalis e X. grisescens foram classificadas enquanto potenciais polinizadores. A autoincompatibilidade e o máximo de frutos produzidos após polinização cruzada são mecanismos reprodutivos favorecidos pelas estratégias fenológicas e síndrome de polinização apresentadas pela espécie.The present work evaluated the importance of the phenological strategies of Senna cana in attracting floral visitors and pollinators in an riparian forest along the Lençóis River, in Chapada Diamantina, Bahia, Brazil. Vegetative and reproductive phenological observations (leaf fall, leaf flushing, flowering, and fruiting were made on a monthly basis among a group of 10 individuals. The floral biology patterns observed included: anthesis, duration of the flowers, stigma receptivity, pollen viability, and the presence of

  17. Plantas medicinais usadas para a saúde bucal pela comunidade do bairro Santa Cruz, Chapada dos Guimarães, MT, Brasil Medicinal plants used for oral health in the Santa Cruz neighborhood, Chapada dos Guimarães, Mato Grosso State, Brazil

    Directory of Open Access Journals (Sweden)

    Aneliza Meireles Borba

    2006-12-01

    Full Text Available Em Mato Grosso, populações tradicionais recorrem ao uso de espécies vegetais como alternativa terapêutica. Na cidade de Chapada dos Guimarães, o bairro Santa Cruz se destaca por abrigar famílias nascidas em áreas urbanas ou rurais que conservam esses conhecimentos transmitidos por gerações. Esta pesquisa tem como objetivo o levantamento das plantas medicinais utilizadas pela comunidade local, indicações terapêuticas, preparos e modos de uso visando a manutenção e recuperação da saúde bucal. Foram entrevistados 40 residentes, através de abordagem qualitativa, usando entrevista semi-estruturada. As espécies catalogadas foram depositadas para identificação no UFMT/Herbário Central. Foram citadas 87 espécies pertencentes a 48 famílias utilizadas na saúde bucal, encontradas no bioma Cerrado ou cultivadas nas residências. Conforme as afecções bucais citadas, as espécies utilizadas são: para erupção dentária: camomila (Matricaria chamomilla L.; candidíases, estomatites, gengivites e afta: açafrão (Crocus sativus L.; dor de dente: arnica-da-serra (Brickelia brasiliensis (Spreng. Robinson. A folha foi a parte da planta mais usada e o chá, por decocção, modo de preparo mais comum. Pessoas idosas, líderes comunitários, parteiras e benzedeiras entrevistados apresentaram um maior conhecimento sobre o assunto. Constatou-se que a comunidade utiliza espécies vegetais, nativas do cerrado ou exóticas, com finalidade terapêutica para manutenção e recuperação da saúde bucal, sendo uma alternativa tradicional, econômica e atuante.In the State of Mato Grosso, traditional populations turn to the use of many plant species as a therapeutic alternative. In the city of Chapada dos Guimarães, the Santa Cruz neighborhood is well known for harboring families from urban and rural communities who preserve this knowledge passed down through many generations. The objective of this research was to survey the medicinal plants used

  18. Efeito do tempo pós-queimada sobre comunidades de Tephritidae (Diptera em áreas de cerrado na Chapada dos Guimarães – MT

    Directory of Open Access Journals (Sweden)

    Kellen Fávero

    2010-07-01

    Abstract. The objectives of this study were to: (i analyze the richness, abundance, and occurrence of endophagous insects in capitula of Asteraceae at Chapada dos Guimarães; (ii evaluate the effect of post-fire time on the richness, abundance, and distribution of endophagous Tephritidae species. Thirteen cerrado areas were sampled, onto which a 250m × 2m transect was established over a topographic isocline. All capitula from individual plants were collected and maintained in screened rearing pots. Three hundred and forty-one individuals belonging to seven species emerged from the flowerheads. Cecidochares and Xanthaciura were the best-represented genera in relation to the number of species. Most insects emerged from capitula collected at a single locality. Only Xanthaciura chrysura (Thomson occurred in all of the sampled localities at which emerged insects were obtained. The time elapsed after the last fire did not have a significant effect on the richness, abundance, and distribution of endophagous Tephritidae species.

  19. Histological evidence of reproductive activity in lizards from the APM Manso, Chapada dos Guimarães, Mato Grosso State, Brazil =Evidências histológicas da atividade reprodutiva em lagartos da região da APM Manso, Chapada dos Guimarães, Estado do Mato Grosso, Brasil

    Directory of Open Access Journals (Sweden)

    Christine Strüssmann

    2012-07-01

    Full Text Available The construction of dams causes major impacts on fauna by changing or eliminating irreversibly their habitats. The resulting changes lead to deep potential modifications on reproductive biology and population structure of lizards, snakes and amphisbaenas. The reservoir in the Multiple Use Area of Manso (APM-Manso is located near to Chapada dos Guimarães National Park, in Mato Grosso State. We analyzed comparatively the male gonads of Anolis meridionalis, Colobosaura modesta, Cercosaura ocellata, Cnemidophorus ocellifer, Hoplocercus spinosus, Bachia bresslaui, Mabuya frenata, Micrablepharus atticolus and Tropidurus oreadicus, from APM-Manso, aiming to verify possible changes in the reproductive success according to environmental changes. Before the impoundment A. meridionalis, Colobosaura modesta, Cercosaura ocellata, M. atticolus and T. oreadicus showed up reproductive. However, during the impoundment period they presented changes in seminiferous tubules, evidenced by the absence of spermatids and spermatozoids. B. bresslaui and M. frenata had no differences in the seminiferous tubules before and after the impoundment, being reproductive in both moments. The damming and the formation of the lake of Manso reservoir may have interfered on the reproduction of some lizards species, especially if the reproductive cycle is regulated by the rainfall of the habitat.A construção de barragens tem ocasionado grandes impactos sobre a fauna ao alterar ou eliminar seus habitats de forma irreversível. Alterações decorrentes exercem profundas modificações potenciais na biologia reprodutiva e na estrutura populacional de lagartos, serpentes e anfisbenas. O reservatório da Área de Aproveitamento Múltiplo de Manso (APM-Manso localiza-se próximo ao Parque Nacional da Chapada dos Guimarães, em Mato Grosso. Foram analisadas comparativamente as gônadas masculinas de Anolis meridionalis, Colobosaura modesta, Cercosaura ocellata, Cnemidophorus ocellifer

  20. X-ray photoelectron spectroscopy study of BaWO{sub 4} and Ba{sub 2}CaWO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Capece, Angela M., E-mail: acapece@pppl.gov [California Institute of Technology, Pasadena, CA (United States); Polk, James E. [Jet Propulsion Laboratory, Pasadena, CA (United States); Shepherd, Joseph E. [California Institute of Technology, Pasadena, CA (United States)

    2014-12-15

    Highlights: • XPS reference spectra for Ba{sub 2}CaWO{sub 6} and BaWO{sub 4} are presented. • Binding energies of Ba 3d and W 4f lines are 0.7 eV higher for BaWO{sub 4} than Ba{sub 2}CaWO{sub 6}. • Ca 2p spectrum contains two sets of Ca 2p doublets attributed to Ba{sub 2}CaWO{sub 6} and CaCO{sub 3}. - Abstract: XPS reference spectra for Ba{sub 2}CaWO{sub 6} and BaWO{sub 4} are presented, including high resolution spectra of the Ba 3d, W 4f, C 1s, Ca 2p, and O 1s lines. The peak locations and full widths at half maximum are also given. The binding energies of the Ba 3d and W 4f lines are 0.7 eV higher for BaWO{sub 4} than for Ba{sub 2}CaWO{sub 6}. The Ca 2p spectrum contains two sets of Ca 2p doublets that were attributed to Ba{sub 2}CaWO{sub 6} and CaCO{sub 3}.

  1. Polarizabilities of Ba and Ba2: Comparison of molecular beam experiments with relativistic quantum chemistry

    International Nuclear Information System (INIS)

    Schaefer, Sascha; Mehring, Max; Schaefer, Rolf; Schwerdtfeger, Peter

    2007-01-01

    The dielectric response to an inhomogeneous electric field has been investigated for Ba and Ba 2 within a molecular beam experiment. The ratio of the polarizabilities per atom of Ba 2 and Ba is determined to be 1.30±0.13. The experimental result is compared to a high level ab initio quantum chemical coupled cluster calculation with an energy-consistent scalar relativistic small-core pseudopotential for Ba. For the barium atom a polarizability of 40.82 A 3 is obtained and the isotropic value of the polarizability calculated for Ba 2 is 97.88 A 3 , which is in good agreement with the experimental results, demonstrating that a quantitative understanding of the interaction between two closed-shell heavy element metal atoms has been achieved

  2. Ba incorporation in benthic foraminifera

    NARCIS (Netherlands)

    de Nooijer, L.J.; Brombacher, Anieke; Mewes, A.; Langer, Gerald; Nehrke, G.; Bijma, Jelle; Reichart, G.J.

    2017-01-01

    Barium (Ba) incorporated in the calcite of many foraminiferal species is proportional to the concentration of Ba in seawater. Since the open ocean concentration of Ba closely follows seawater alkalinity, foraminiferal Ba ∕ Ca can be used to reconstruct the latter. Alternatively, Ba ∕ Ca from

  3. Demanda turística por destinos com severas limitações de acesso: casos brasileiros

    Directory of Open Access Journals (Sweden)

    Glauber E.O. Santos

    2017-01-01

    Full Text Available One of the main strategies of the Brazilian Tourism Ministry to increase tourist flows at national destinations was the nomination of 65 key destinations for tourism in the country. This research aimed to analyze the leisure tourism demand for key destinations with severe access limitations. A survey was conducted with tourists of 3 selected key destinations: Diamantina (MG, Parnaíba (PI and Lençóis (BA. The main findings indicate the predominance of tourists of middle age, males and varied income levels. São Paulo is the single most important market for all 3 destinations. Among the main conclusions are the questioning of the key role of these destinations for tourism, and the positive opinion of tourists about access conditions, despite the large distances travelled (average of 1,333 Km and the fact that a significant share of them used mainly inland modes of transport.

  4. Alpha decay of 114Ba

    International Nuclear Information System (INIS)

    Mazzocchi, C.; Janas, Z.; Batist, L.; Belleguic, V.; Doering, J.; Kapica, M.; Kirchner, R.; Roeckl, E.; Gierlik, M.; Zylicz, J.; Mahmud, H.; Schmidt, K.; Woods, P.J.

    2003-01-01

    The neutron-deficient isotope 114 Ba was produced in a fusion evaporation reaction at the GSI On-Line Mass Separator. We measured the α-particle energy of 114 Ba, the half-life of its daughter nucleus 110 Xe, and the α-decay branching ratios for 114 Ba, 110 Xe and 106 Te. (orig.)

  5. Effect of local environment on crossluminescence kinetics in SrF{sub 2}:Ba and CaF{sub 2}:Ba solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Terekhin, M.A. [P.N. Lebedev Physical Institute, Leninskij Prospekt 53, 119991 Moscow (Russian Federation); Makhov, V.N., E-mail: makhov@sci.lebedev.ru [P.N. Lebedev Physical Institute, Leninskij Prospekt 53, 119991 Moscow (Russian Federation); Lebedev, A.I.; Sluchinskaya, I.A. [Lomonosov Moscow State University, Moscow 119991 (Russian Federation)

    2015-10-15

    Spectral and kinetic properties of extrinsic crossluminescence (CL) in SrF{sub 2}:Ba (1%) and CaF{sub 2}:Ba (1%) are compared with those of intrinsic CL in BaF{sub 2} and are analyzed taking into account EXAFS data obtained at the Ba L{sub III} edge and results of first-principles calculations. The CL decay time was revealed to be longer in SrF{sub 2}:Ba and CaF{sub 2}:Ba compared to BaF{sub 2}. This fact contradicts the expected acceleration of luminescence decay which could result from an increased overlap of wave functions in solid solutions due to shortening of the Ba-F distance obtained in both EXAFS measurements and first-principles calculations. This discrepancy is explained by the effect of migration and subsequent non-radiative decay of the Ba (5p) core holes in BaF{sub 2} and by decreasing of the probability of optical transitions between Ba (5p) states and the valence band in SrF{sub 2}:Ba and CaF{sub 2}:Ba predicted by first-principles calculations. - Highlights: • The crossluminescence kinetics in SrF{sub 2}:Ba and CaF{sub 2}:Ba is slower than in BaF{sub 2}. • Ba{sup 2+} ions substitute for host Ca{sup 2+}(Sr{sup 2+}) ions in the on-center positions. • The nearest Ba-F distances in SrF{sub 2}:Ba and CaF{sub 2}:Ba are shorter than in BaF{sub 2}. • EXAFS data and first-principles calculations of the local structure agree well. • First-principles calculations explain slower luminescence decay in solid solutions.

  6. Documenting Architectural Heritage in Bahia, Brazil, Using Spherical Photogrammetry

    Science.gov (United States)

    De Amorim, A. L.; Fangi, G.; Malinverni, E. S.

    2013-07-01

    The Cultural Heritage disappears at a rate higher than we are able, not only, to restore but also to document: human and natural factors, negligence or worst, deliberate demolitions put in danger the collective Architectural Heritage (AH). According to CIPA statements, the recording is important and has to follow some guidelines. The Architectural and Urban Heritage data have to be historically related, critically assessed and analyzed, before to be organized according to a thematic structure and become available for further uses. This paper shows the experiences developed by the Laboratory of Computer Graphics applied to Architecture and Design (LCAD), at the Architecture School of the Federal University of Bahia (FAUFBA), Brazil, in cooperation with the Università Politecnica delle Marche (UNIVPM, DICEA Department), Italy, in documenting architectural heritage. The research set up now has been carried out in the historical sites of Bahia, as Pelourinho neighborhood, a World Heritage by UNESCO. Other historical sites are in the plan of this survey, like the cities of Lençóis and Mucugê in Chapada Diamantina region. The aim is to build a technological platform based on low cost digital technologies and open source tools, such as Panoramic Spherical Photogrammetry, Spatial Database, Geographic Information Systems, Three-dimensional Geometric Modeling, CAD technology, for the collection, validation and dissemination of AH.

  7. U-Pb (SHRIMP) and Sm-Nd geochronology of basaltic green schists of the Aracuai orogen: implications for the age of the Macaubas group; Geocronologia U-Pb (SHRIMP) e Sm-Nd de xistos verdes basalticos do orogeno Aracuai: implicacoes para a idade do grupo Macaubas

    Energy Technology Data Exchange (ETDEWEB)

    Babinski, Marly [Universidade de Sao Paulo, SP (Brazil). Inst. de Geociencias. Centro de Pesquisas Geocronologicas]. E-mail: babinski@usp.br; Gradim, Rafael Jaude; Alkmim, Fernando Flecha de [Universidade Federal de Ouro Preto, MG (Brazil). Escola de Minas. Dept. de Geologia]. E-mails: rafaelgradim@gmail.com; alkmim@degeo.ufop.br; Pedrosa-Soares, Antonio Carlos; Noce, Carlos Mauricio [Minas Gerais Univ., Belo Horizonte (Brazil). Inst. de Geociencias; Liu, Dunyi [Chinese Academy of Geological Sciences, Beijing (China). Beijing SHRIMP Lab.

    2005-12-15

    The age and stratigraphic position of the basaltic green schists of the Rio Preto valley, located in the western part of the Aracuai Belt (ca. 60 km north of Diamantina, Minas Gerais) were a matter of controversy in the geologic literature, because several authors correlated them to the Neo proterozoic Macaubas Group but others to the lower Espinhaco Supergroup (ca. 1.7 Ga). However, detailed studies demonstrate that these green schists represent an interplay of submarine basaltic volcanism, volcanoclastic sedimentation and fire fountaining, and that they belong to the Chapada Acaua Formation of the Macaubas Group (Gradim et al., 2005). Geochemical studies indicate that the green schist protoliths evolved in a continental intra plate environment. Zircon crystals were separated from a green schist sample and analyzed by the U-Pb SHRIMP method. A Sm-Nd whole-rock isotopic analysis was obtained from the same sample. The Sm- Nd model age of ca. 1.52 Ga suggests that the green schist protoliths are younger than the magmatism of the Espinhaco rift. Most analyzed zircon crystals show features of detrital grains. The older ages indicate zircon grains inherited from the Archean- Paleoproterozoic basement and from magmatic rocks of the Espinhaco rift. The younger U-Pb values constrain the maximum age of the green schist protoliths at ca. 1,16 Ga. (author)

  8. Improvement of the field-trapping capabilities of bulk Nd Ba Cu O superconductors using Ba Cu O substrates

    Science.gov (United States)

    Matsui, Motohide; Nariki, Shinya; Sakai, Naomichi; Iwafuchi, Kengo; Murakami, Masato

    2006-07-01

    We used Ba-Cu-O substrates to fabricate bulk Nd-Ba-Cu-O superconductors using a top-seeded melt-growth method. There were several advantages for the use of Ba-Cu-O substrate compared to conventional substrate materials such as MgO, ZrO2, Al2O3, RE123 and RE211 (RE = rare earth). The Ba-Cu-O did not react with the precursor and minimized liquid loss. Accordingly, the introduction of large-sized cracks was suppressed. We also found that Tc values were high at the bottom regions, which was ascribed to the beneficial effect of Ba-Cu-O in suppressing Nd/Ba substitution. As a result, we obtained bulk Nd-Ba-Cu-O superconductors that exhibited fairly good field-trapping capabilities, even at the bottom surfaces.

  9. Co2FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

    Directory of Open Access Journals (Sweden)

    J. Rogge

    2015-07-01

    Full Text Available We succeed to integrate BaO as a tunneling barrier into Co2FeAl based magnetic tunnel junctions (MTJs. By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR ratio of -10% is found for Co2FeAl (24 nm / BaO (5 nm / Fe (7 nm MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM, it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double layer barrier, the electric stability could effectively be increased by a factor of five. The resulting TMR effect is found to be about +20% at room temperature, although a fully antiparallel state has not been realized.

  10. Structural and electrical properties of Barium Titanate (BaTiO3 and Neodymium doped BaTiO3 (Ba0.995Nd0.005TiO3

    Directory of Open Access Journals (Sweden)

    Tuan Sulong Tuan Amirah

    2017-01-01

    Full Text Available Barium titanate (BaTiO3 and Neodymium (Nd doped BaTiO3 with composition Ba0.995Nd0.005TiO3 were prepared using conventional solid state reaction method to study the dielectric properties of materials. Pure phase samples were found at final heating temperature of 1400°C for overnight. X-ray diffraction analysis reveals the changes in the lattice parameter and unit cell volume of the pure perovskite tetragonal structure with space group (P4mm. Electrical analysis is carried out to investigate the dielectric properties, conductivity behaviour and dielectric loss of BaTiO3 and Ba0.995Nd0.005TiO3. Ba0.995Nd0.005TiO3 have a broaden dielectric peaks with high permittivity of 8000 and reasonably low loss tan δ which is about 0.004 (1 kHz.

  11. Chalcogenidosilicates: Ba/sub 2/SiTe/sub 4/ and Ba/sub 2/SiSe/sub 4/

    Energy Technology Data Exchange (ETDEWEB)

    Brinkmann, C; Eisenmann, B; Schaefer, H [Technische Hochschule Darmstadt (Germany, F.R.). Fachbereich Anorganische Chemie und Kernchemie

    1985-05-01

    The new compounds Ba/sub 2/SiSe/sub 4/ and Ba/sub 2/SiTe/sub 4/ crystallize in the monoclinic system, space group: P2/sub 1//m (No. 11) with the lattice constants Ba/sub 2/SiSe/sub 4/: a = 918.4(5) pm, b = 703.3(3) pm, c = 687.2(3) pm, ..beta.. = 109.2(1)/sup 0/, Ba/sub 2/SiTe/sub 4/: a = 965.0(5) pm, b = 762.6(3) pm, c = 746.6(3) pm, ..beta.. = 108.9(1)/sup 0/. Both compounds are isotypic to the Sr/sub 2/GeS/sub 4/ structure. Ba/sub 2/SiTe/sub 4/ is the first o-telluridosilicate with discrete SiTe/sub 4//sup 4 -/ anions.

  12. Stellar Laboratories: 3. New Ba 5, Ba 6, and Ba 7 Oscillator Strengths and the Barium Abundance in the Hot White Dwarfs G191-B2B and RE 0503-289

    Science.gov (United States)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, Jeffrey Walter

    2014-01-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims. Reliable Ba 5-7 oscillator strengths are used to identify Ba lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ba abundances. Methods. We newly calculated Ba v-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Ba lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results. For the first time, we identified highly ionized Ba in the spectra of hot white dwarfs. We detected Ba vi and Ba vii lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The Ba vi/Ba vii ionization equilibrium is well reproduced with the previously determined effective temperature of 70 000 K and surface gravity of log g=7.5. The Ba abundance is 3.5 +/- 0.5 × 10(exp-4) (mass fraction, about 23 000 times the solar value). In the FUSE spectrum of G191-B2B, we identified the strongest Ba vii line (at 993.41 Å) only, and determined a Ba abundance of 4.0 +/- 0.5 × 10(exp-6) (about 265 times solar). Conclusions. Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Ba vi-vii line profiles in two white dwarfs' (G191-B2B and RE 0503-289) far-ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed to determine the photospheric Ba abundance of these two stars precisely.

  13. Espécies de plantas visitadas por Heliactin bilophus (Aves, Trochilidae na Chapada dos Veadeiros, durante a estação chuvosa

    Directory of Open Access Journals (Sweden)

    Gabriel Baruffaldi Ghiringhello

    2009-06-01

    Os hábitos alimentares do beija-flor Heliactin bilophus ainda são pouco conhecidos. Este trabalho teve como objetivo identificar as espécies de plantas mais visitadas por H. bilophus com finalidades de alimentação (consumo de néctar durante a estação chuvosa no Parque Nacional da Chapada dos Veadeiros, em Goiás. as observações foram realizadas em duas estações chuvosas (janeiro de 2006 e fevereiro de 2008. A metodologia baseou-se em percorrer trilhas em duas áreas de campo sujo e em duas de campo rupestre. Todo registro de um indivíduo consumindo néctar de uma planta em flor foi considerado como uma visita. Foram observadas 296 visitas, compreendendo oito espécies de plantas dos estratos arbustivo e herbáceo. as espécies mais frequentemente visitadas foram Bauhinia tenella (Caesalpinoideae e Vochysia pumila (Vochysiaceae em campo sujo, e Lychnophora ericoides (asteraceae, em campo rupestre. Essas três espécies foram comumente encontradas nos locais de estudo. Nas duas fisionomias, Heliactin bilophus consumiu néctar de poucas espécies de plantas. as espécies mais frequentemente visitadas apresentavam flores em abundância.

  14. The BaBar Mini

    International Nuclear Information System (INIS)

    Brown, David N.

    2003-01-01

    BaBar has recently deployed a new event data format referred to as the Mini. The mini uses efficient packing and aggressive noise suppression to represent the average reconstructed BaBar event in under 7 KBytes. The Mini packs detector information into simple transient data objects, which are then aggregated into roughly 10 composite persistent objects per event. The Mini currently uses Objectivity persistence, and it is being ported to use Root persistence. The Mini contains enough information to support detailed detector studies, while remaining small and fast enough to be used directly in physics analysis. Mini output is customizable, allowing users to both truncate unnecessary content or add content, depending on their needs. The Mini has now replaced three older formats as the primary output of BaBar event reconstruction. A reduced form of the Mini will soon replace the physics analysis format as well, giving BaBar a single, flexible event data format covering all its needs

  15. The BaBar mini

    International Nuclear Information System (INIS)

    Brown, David N.; BaBar Collaboration

    2003-01-01

    BaBar has recently deployed a new event data format referred to as the Mini. The mini uses efficient packing and aggressive noise suppression to represent the average reconstructed BaBar event in under 7 KBytes. The Mini packs detector information into simple transient data objects, which are then aggregated into roughly 10 composite persistent objects per event. The Mini currently uses Objectivity persistence, and it is being ported to use Root persistence. The Mini contains enough information to support detailed detector studies, while remaining small and fast enough to be used directly in physics analysis. Mini output is customizable, allowing users to both truncate unnecessary content or add content, depending on their needs. The Mini has now replaced three older formats as the primary output of BaBar event reconstruction. A reduced form of the Mini will soon replace the physics analysis format as well, giving BaBar a single, flexible event data format covering all its needs

  16. A variação de preposições com verbo ir de movimento em comunidades rurais do semiárido baiano A variação de preposições com verbo ir de movimento em comunidades rurais do semiárido baiano

    Directory of Open Access Journals (Sweden)

    Hilmara Moura de JESUS

    2012-06-01

    Full Text Available This article consists in the analysis of variable regency of the verb ir concerning movement in the dialect from communities of Matinha, district of Feira de Santana, Piabas, located in the city of Caem, a former district of Jacobina, Barra / Bananal and MatoGrosso, in ChapadaDiamantina, Casinhas, Tapera e Lagoa do Inácio, in Jeremoabo. For the development of research, we used a sample drawn from 72 informants who make up the corpus of the project “A Língua Portuguesa no Semi-áridoBaiano”. Based on the ambit of Sociolinguistics Variacionist, the present study is aimed to describe the phenomenon of change involving the prepositions a, para e em introduced by the verb ir of movement and examine the factors that influence (linguistic and sociolinguistic the use of these prepositions. The results hint at a change practically concluded, since it had found only six instances with the preposition a. Among the 582 events that constitute the corpora are highlighted with 418 achievements for the variant para (71% and 164 with the variant em (29%. The statistical Goldvarb 2001 shows the variables degree of definiteness of the locative name, stay in place, the person speaking, community, tense, sex / gender, education, (indetermination of the subject and speech narrative as the determining variable in the regency of the verb irof movement.Este artigo consiste na análise da regência variável do verbo ir de movimento no dialeto das comunidades de Matinha, distrito de Feira de Santana, Piabas, localizada no município de Caém, antigo distrito de Jacobina, Barra/Bananal e Mato Grosso, na Chapada Diamantina, Casinhas, Tapera e Lagoa do Inácio, em Jeremoabo. Para o desenvolvimento da pesquisa, foi utilizada uma amostra extraída de 72 informantes que compõem o corpus do Projeto “A Língua Portuguesa no Semiárido Baiano”. Baseado no âmbito da Sociolingu

  17. Biomassa microbiana e matéria orgânica leve em solos sob sistemas agrícolas orgânico e convencional na Chapada da Ibiapaba - CE Microbial biomass and light organic matter in soils under organic and conventional systems in the Chapada da Ibiapaba - CE, Brazil

    Directory of Open Access Journals (Sweden)

    Francisco Alisson da Silva Xavier

    2006-04-01

    Full Text Available Em muitos casos, a substituição da vegetação nativa por sistemas agrícolas resulta em decréscimo nos conteúdos de C e N nos diferentes compartimentos da matéria orgânica do solo. Para testar se as práticas de manejo que priorizam o aporte de resíduos orgânicos promovem aumento dos compartimentos da matéria orgânica mais sensíveis ao manejo, este estudo se propôs estudar áreas de uma propriedade que utiliza um sistema de produção de acerola em larga escala, sob manejo orgânico, e uma área sob cultivo convencional de cenoura e beterraba em rotação com milho, pertencentes à Fazenda Amway Nutrilite do Brasil e à Associação de Horticultores do Pivot Central, respectivamente, ambas localizadas na região da Chapada da Ibiapaba, Ceará. Selecionou-se, também, uma área de pastagem localizada no interior da primeira propriedade amostrada, bem como áreas sob mata nativa, próximas às áreas de cultivo. Amostras de um Neossolo Quartzarênico foram coletadas nas profundidades de 0-5 e 5-15 cm e foram determinados os teores de C orgânico total, de C e N microbiano (Cmic e Nmic e da matéria orgânica leve (Cmol e Nmol, além do C mineralizável obtido por respirometria. O acúmulo médio nos estoques de Nmic nas áreas sob manejo orgânico em relação à mata nativa foi de 11,7 kg ha-1, o que representou um incremento de 585 % de Nmic nas áreas de cultivo. Já na pastagem, ocorreu acúmulo de 211 kg ha-1 no estoque de Cmic em relação à mata nativa em subsuperfície, representando um incremento de 514,6 %. Por outro lado, os estoques de Cmic no cultivo convencional sofreram reduções de 59 e 53 %, nas camadas de 0-5 e de 5-15 cm, respectivamente, em relação à mata nativa. Os estoques de Cmol obtidos nas linhas de cultivo nos sistemas orgânicos apresentaram incremento de 106 %, na camada de 0-5 cm, em relação à mata; no sistema convencional, porém, constatou-se uma redução em 31 % no estoque de Cmol na camada

  18. Back-contacted BaSi

    NARCIS (Netherlands)

    Vismara, R.; Isabella, O.; Zeman, M.

    2017-01-01

    We present the optical investigation of a novel back-contacted architecture for solar cells based on a thin barium (di)silicide (BaSi2) absorber. First, through the analysis of absorption limits of different semiconducting materials, we show the potential of BaSi2 for

  19. Octupole correlations in neutron-rich {sup 143,145}Ba and a type of superdeformed band in {sup 145}Ba

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, S.J.; Wang, M.G.; Long, G.L.; Zhu, L.Y.; Gan, C.Y.; Yang, L.M.; Sakhaee, M.; Li, M.; Deng, J.K. [Physics Department, Tsinghua University, Beijing 100084, Peoples Republic of (China); Zhu, S.J.; Hamilton, J.H.; Ramayya, A.V.; Jones, E.F.; Hwang, J.K.; Zhang, X.Q.; Gore, P.M.; Peker, L.K.; Drafta, G.; Babu, B.R.; Deng, J.K.; Ginter, T.N.; Beyer, C.J.; Kormicki, J.; Ter-Akopian, G.M.; Daniel, A.V. [Physics Department, Vanderbilt University, Nashville, Tennessee 37235 (United States); Zhu, S.J.; Ter-Akopian, G.M.; Daniel, A.V. [Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee 37831 (United States); Ma, W.C. [Physics Department, Mississippi State University, Mississippi 39762 (United States); Cole, J.D.; Aryaeinejad, R.; Drigert, M.W. [Idaho National Engineering Laboratory, Idaho Falls, Idaho 83415 (United States); Rasmussen, J.O.; Asztalos, S.; Lee, I.Y.; Macchiavelli, A.O.; Chu, S.Y.; Gregorich, K.E.; Mohar, M.F. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ter-Akopian, G.M.; Daniel, A.V.; Oganessian, Y.T.; Kliman, J. [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna (Russia); Donangelo, R. [Universidade Federal do Rio de Janeiro, Caixa Postal 68528, RG (Brazil); Stoyer, M.A.; Lougheed, R.W.; Moody, K.J.; Wild, J.F. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Prussin, S.G. [Nuclear Engineering Department, University of California at Berkeley, Berkeley, California 94720 (United States); Kliman, J. [Institute of Physics, SASc, Dubravskacesta 9, 84228 Bratislava (Slovakia); Griffin, H.C. [University of Michigan, Ann Arbor, Michigan 48104 (United States)

    1999-11-01

    High spin states in neutron-rich odd-{ital Z} {sup 143,145}Ba nuclei have been investigated from the study of prompt {gamma} rays in the spontaneous fission of {sup 252}Cf by using {gamma}-{gamma}- and {gamma}-{gamma}-{gamma}- coincidence techniques. Alternating parity bands are identified for the first time in {sup 145}Ba and extended in {sup 143}Ba. A new side band, with equal, constant dynamic, and kinetic moments of inertia equal to the rigid body value, as found in superdeformed bands, is discovered in {sup 145}Ba. Enhanced E1 transitions between the negative- and positive-parity bands in these nuclei give evidence for strong octupole deformation in {sup 143}Ba and in {sup 145}Ba. These collective bands show competition and coexistence between symmetric and asymmetric shapes in {sup 145}Ba. Evidence is found for crossing M1 and E1 transitions between the s=+i and s={minus}i doublets in {sup 143}Ba. {copyright} {ital 1999} {ital The American Physical Society}

  20. Phonon dispersion curves of BCC Ba

    International Nuclear Information System (INIS)

    Mizuki, J.; Stassis, C.; Zarestky, J.

    1985-01-01

    Ba, as well as Sr and Ca, is a divalent alkaline earth metal. At room temperature and ambient pressure, the structure of Ba is bcc, whereas that of Sr and Ca is fcc. Under pressure, the bcc phase of Ba transforms to an hcp structure at 55 kbar. Also, at 37 kbar Ba becomes a superconductor with T/sub c/ = 0.06 K. These properties are highly dependent on the position of the d bands relative to the Fermi level. Experimental investigation of the elastic and lattice dynamical properties of these metals has been hindered by difficulties in growing single crystals. However, recently the authors were able to grow several single crystals of bcc Ba of sufficient volume for inelastic neutron scattering experiments. Some of the results are summarized here

  1. Hyperfine structure and isotope shift of the neutron-rich barium isotopes 139-146Ba and 148Ba

    International Nuclear Information System (INIS)

    Wendt, K.; Ahmad, S.A.; Klempt, W.; Neugart, R.; Otten, E.W.

    1988-01-01

    The hyperfine structure and isotope shift in the 6s 2 S 1/2 -6p 2 P 3/2 line of Ba II (455.4 nm) have been measured by collinear fast-beam laser spectroscopy for the neutron-rich isotopes 139-146 Ba and 148 Ba. Nuclear moments and mean square charge radii of these isotopes have been recalculated. The isotope shift of the isotope 148 Ba (T 1/2 = 0.64 s) could be studied for the first time, yielding δ 2 > 138,148 = 1.245(3) fm 2 . (orig.)

  2. Syntheses, crystal structures and characterizations of BaZn(SeO3)2 and BaZn(TeO3)Cl2

    International Nuclear Information System (INIS)

    Jiang Hailong; Feng Meiling; Mao Jianggao

    2006-01-01

    Two new barium zinc selenite and tellurite, namely, BaZn(SeO 3 ) 2 and BaZn(TeO 3 )Cl 2 , have been synthesized by the solid state reaction. The structure of BaZn(SeO 3 ) 2 features double chains of [Zn(SeO 3 ) 2 ] 2- anions composed of four- and eight-member rings which are alternatively along a-axis. The double chains of [Zn 2 (TeO 3 ) 2 Cl 3 ] 3- anions in BaZn(TeO 3 )Cl 2 are formed by Zn 3 Te 3 rings in which each tellurite group connects with three ZnO 3 Cl tetrahedra. BaZn(SeO 3 ) 2 and BaZn(TeO 3 )Cl 2 are wide bandgap semiconductors based on optical diffuse reflectance spectrum measurements. -- Graphical abstract: Two new barium zinc selenite and tellurite, namely, BaZn(SeO 3 ) 2 and BaZn(TeO 3 )Cl 2 , have been synthesized by solid state reaction. The structure of BaZn(SeO 3 ) 2 features 1D double chains of [Zn(SeO 3 ) 2 ] 2- anions composed of four- and eight-member rings which are alternatively along a-axis. The 1D double chains of [Zn 2 (TeO 3 ) 2 Cl 3 ] 3- anions in BaZn(TeO 3 )Cl 2 are formed by Zn 3 Te 3 rings in which each tellurite group connects with one ZnO 3 Cl and two ZnO 2 Cl 2 tetrahedra. BaZn(SeO 3 ) 2 and BaZn(TeO 3 )Cl 2 are wide bandgap semiconductors based on optical diffuse reflectance spectrum measurements

  3. Sistema reprodutivo de Anadenanthera peregrina (L. Speg e Vochysia haenkiana (Spreng. Mart. em fragmento de cerrado na Chapada dos Guimarães - MT Reprodutive system of Anadenanthera peregrina and Vochysia haenkiana in a fragment of "Cerrado forest" from Chapada dos Guimarães - MT, Brazil

    Directory of Open Access Journals (Sweden)

    Reginaldo Brito da Costa

    2003-04-01

    Full Text Available O presente estudo objetivou avaliar o sistema reprodutivo das espécies Anadenanthera peregrina (L. Speg. e Vochysia haenkiana (Spreng. Mart. Foram estudados aspectos do sistema de cruzamento, complementados pelas observações de maturação dos frutos e a germinação das sementes em função dos tipos de cruzamentos testados. As síndromes de dispersão das sementes foram também avaliadas através das características morfológicas dos frutos e sementes. O estudo foi realizado em um fragmento de cerrado com aproximadamente 32 ha, no município de Chapada dos Guimarães, MT, a 15(010' S, 55(035' W, e à altitude de 450m. O delineamento experimental utilizado na determinação do sistema de cruzamento para cada espécie foi o de blocos ao acaso, com seis tratamentos para a espécie Vochysia haenkiana e cinco tratamentos para Anadenanthera peregrina, ambas com três repetições. O sistema de cruzamento detectado para as duas espécies foi o preferencialmente alogâmico, porém, com a possibilidade, não desprezível, de produção de frutos/sementes por autofertilização, sugerindo um aumento gradual de autocompatibilidade genética como estratégia de geração de descendência no ambiente florestal fragmentado. A polinização cruzada em Anadenanthera peregrina é favorecida tanto pelo alto grau de auto-incompatibilidade genética quanto pela protandria detectada. O padrão de maturação dos frutos e sementes e o período de dispersão das sementes foram distintos em ambas as espécies, ocorrendo, entretanto, durante ou no final da estação seca, facilitando a distribuição dos propágulos anemocóricos. A germinação em ambas as espécies foi rápida e em alta percentagem.The study of the breeding system of Anadenanthera peregrina (L. Speg. and Vochysia haenkiana (Spreng. Mart. was the main purpose of this work. It was also studied fruit maturation, seed dispersal and seed germination to characterize the reproductive system of these

  4. Stellar laboratories. III. New Ba v, Ba vi, and Ba vii oscillator strengths and the barium abundance in the hot white dwarfs G191-B2B and RE 0503-289

    Science.gov (United States)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

    2014-06-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: Reliable Ba v-vii oscillator strengths are used to identify Ba lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ba abundances. Methods: We newly calculated Ba v-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Ba lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results: For the first time, we identified highly ionized Ba in the spectra of hot white dwarfs. We detected Ba vi and Ba vii lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The Ba vi/Ba vii ionization equilibrium is well reproduced with the previously determined effective temperature of 70 000 K and surface gravity of log g = 7.5. The Ba abundance is 3.5 ± 0.5 × 10-4 (mass fraction, about 23 000 times the solar value). In the FUSE spectrum of G191-B2B, we identified the strongest Ba vii line (at 993.41 Å) only, and determined a Ba abundance of 4.0 ± 0.5 × 10-6 (about 265 times solar). Conclusions: Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Ba vi-vii line profiles in two white dwarfs' (G191-B2B and RE 0503-289) far-ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed to determine the photospheric Ba abundance of these two stars precisely. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for

  5. Características físico-químicas e polínicas de amostras de méis de Apis mellifera L., 1758 (Hymenoptera, Apidae) da região da chapada do Araripe, município de Santana do Cariri, estado do Ceará.

    OpenAIRE

    Carolina Maranhão Fernandes de Arruda

    2003-01-01

    Com o objetivo de determinar as características físico-químicas e a origem floral de méis produzidos por Apis mellifera L., 1758, na região da Chapada do Araripe, município de Santana do Cariri/Ceará foram determinados no Laboratório de Apicultura do Setor de Entomologia da Escola Superior de Agricultura “Luiz de Queiroz”, USP: os açúcares totais, açúcares redutores, sacarose, umidade, hidroximetilfurfural, proteína, cinzas, pH, acidez, índice de formol, condutividade elétrica, cor, visc...

  6. Modificações nas propriedades dos solos de uma área de manejo florestal na Chapada do Araripe

    Directory of Open Access Journals (Sweden)

    Adriana Oliveira Araújo

    2013-06-01

    Full Text Available A Chapada do Araripe possui grande diversidade ambiental, onde é predominante o Latossolo Vermelho-Amarelo. Nela encontra-se a Floresta Nacional do Araripe (FLONA e várias unidades de manejo florestal (UMF. O objetivo deste estudo foi utilizar a análise multivariada para obter-se um indicador básico que represente um conjunto de atributos físicos, químicos e biológicos utilizados como indicadores de modificações nas propriedades dos solos de uma UMF. Foram analisados, em triplicata, na profundidade de 0-20 cm, solos de 15 pontos da UMF e quatro da FLONA, onde foram determinados nove atributos utilizados na identificação das peculiaridades de grupos de estado de recuperação dos solos e suas principais diferenças. A análise demonstrou que dois componentes principais respondem por aproximadamente 76 % da variância dos dados: o primeiro é o indicador da qualidade biológica, química e física dos solos; e o segundo, do estado de compactação. A análise de agrupamento multivariada, aplicada ao primeiro componente principal, evidenciou a formação de três grupos: um da FLONA e dois contendo amostras da UMF, em diferentes estados de recuperação. A utilização do teste de Tukey em nível de 5 % no agrupamento dos teores de matéria orgânica dos solos apresentou os mesmos grupos da análise de agrupamento multivariada, indicando que esse atributo pode ser utilizado como indicador básico na área de estudo.

  7. High spin structure in 130,131Ba

    International Nuclear Information System (INIS)

    Kaur, Navneet; Kumar, A.; Singh, Amandeep; Kumar, S.; Kaur, Rajbir; Singh, Varinderjit; Behera, B.R.; Singh, K.P.; Singh, G.; Mukherjee, G.; Sharma, H.P.; Kumar, Suresh; Kumar Raju, M.; Madhusudhan Rao, P.V.; Muralithar, S.; Singh, R.P.; Kumar, Rakesh; Madhvan, N.; Bhowmik, R.K.

    2014-01-01

    High spin states of 130,131 Ba have been investigated via fusion evaporation reactions 122 Sn( 13 C,4n) 131 Ba and 122 Sn( 13 C, 5n) 130 Ba at E beam =65 MeV. The level schemes of 130,131 Ba have been extended by placing several new γ transitions. A few interband transitions connecting two negative-parity bands, which are the experimental fingerprints of signature partners, have been established in 130 Ba. Spin and parity of a side band have been assigned in 131 Ba and this dipole band is proposed to have a three-quasiparticle configuration, νh 11/2 x πh 11/2 x πg 7/2 . The observed band structures and nuclear shape evolution as a function of the angular momentum have been discussed in the light of Total-Routhian-Surface calculations. (orig.)

  8. Thermal analysis of formation of nano-crystalline BaTiO3 using Ba(NO32 and TiO2

    Directory of Open Access Journals (Sweden)

    Md. Jawed Ansaree

    2015-12-01

    Full Text Available The reaction of Ba(NO32 with TiO2 was studied by thermogravimetric (TG and differential scanning calorimetric (DSC techniques up to 1000 °C and in nitrogen atmosphere. It was found that the formation of BaTiO3 takes place above 600 °C and that precursor mixing time and heating rate have no effect on the reaction temperature. BaTiO3 powder was prepared by calcination of Ba(NO32 and TiO2 precursor mixture at 800 °C for 8 h. X-ray diffraction analysis of the synthesized BaTiO3 confirmed the formation of tetragonal phase with lattice parameters a = 3.9950±0.0003 Å and c = 4.0318±0.0004 Å. Thermal analysis of the synthesized BaTiO3 powder showed weight loss within temperature range 40–1000 °C of only 0.40%. This small amount of weight loss was connected with some impurity phase, and identified as BaCO3 using Fourier transform infrared (FTIR technique.

  9. Growth and characterization of acentric BaHf(BO{sub 3}){sub 2} and BaZr(BO{sub 3}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mączka, Mirosław, E-mail: m.maczka@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Szymborska-Małek, Katarzyna; Gągor, Anna [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Majchrowski, Andrzej [Institute of Applied Physics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland)

    2015-05-15

    Growth, single crystal X-ray diffraction, polarized Raman and infrared (IR) studies of BaHf(BO{sub 3}){sub 2} are presented. Raman and IR spectra of polycrystalline BaZr(BO{sub 3}){sub 2} are also reported to facilitate assignment of modes. BaHf(BO{sub 3}){sub 2} borate crystallizes in trigonal system, space group R3c, with lattice parameters: a=5.1540(4) Å, c=33.901(3) Å. It accommodates dolomite-like structure doubled in the c direction, which is built of alternating layers of HfO{sub 6} octahedra and BaO{sub 6} distorted trigonal prisms that are connected through borate groups. The obtained structural as well as spectroscopic data show that BaHf(BO{sub 3}){sub 2} is isostructural with BaZr(BO{sub 3}){sub 2} and the deviations from centrosymmetry is small. - Graphical abstract: Arrangement of BO{sub 3} groups in BaHf(BO{sub 3}){sub 2} along the c direction in one unit cell. Dark and light blue denote different borate groups. - Highlights: • BaHf(BO{sub 3}){sub 2} single crystals were grown. • X-ray diffraction showed that this borate crystallizes in the acentric R3c structure. • Raman and IR spectra were measured for BaHf(BO{sub 3}){sub 2} and BaZr(BO{sub 3}){sub 2}, respectively. • Assignment of modes is proposed.

  10. Synthesis of BaTiO3 nanoparticles from TiO2-coated BaCO3 particles derived using a wet-chemical method

    Directory of Open Access Journals (Sweden)

    Yuuki Mochizuki

    2014-03-01

    Full Text Available BaCO3 particles coated with amorphous TiO2 precursor are prepared by a wet chemical method to produce BaTiO3 nanoparticles at low temperatures. Subsequently, we investigate the formation behavior of BaTiO3 particles and the particle growth behavior when the precursor is subjected to heat treatment. The state of the amorphous TiO2 coating on the surface of BaCO3 particles depends on the concentration of NH4HCO3, and the optimum concentration is found to be in the range 0.5–1.0 M. Thermogravimetric curves of the BaCO3 particles coated with the TiO2 precursor, prepared from BaCO3 particles of various sizes, show BaTiO3 formation occurring mainly at 550–650 °C in the case of fine BaCO3 particles. However, as evidenced from the curves, the temperature of formation of BaTiO3 shifts to higher values with an increase in the size of the BaCO3 particles. The average particle size of single phase BaTiO3 at heat-treatment temperature of 650–900 °C is observed to be in the range 60–250 nm.

  11. Spectral analysis of Pr{sup 3+} doped germanate glasses modified by BaO and BaF{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Pisarska, Joanna, E-mail: joanna.pisarska@us.edu.pl [University of Silesia, Institute of Chemistry, Szkolna 9 Street, 40-007 Katowice (Poland); Pisarski, Wojciech A. [University of Silesia, Institute of Chemistry, Szkolna 9 Street, 40-007 Katowice (Poland); Dorosz, Dominik; Dorosz, Jan [Bialystok University of Technology, Faculty of Electrical Engineering, Wiejska 45D Street, 15-351 Bialystok (Poland)

    2016-03-15

    Luminescence properties of Pr{sup 3+} ions in germanate glasses modified by BaF{sub 2} were investigated. Several luminescence bands originating to transitions from the {sup 3}P{sub 0} state to the lower-lying states of Pr{sup 3+} were registered under 450 nm excitation. The spectral analysis suggests that the positions of luminescence bands and their relative intensities are changed significantly with BaF{sub 2} content. The relative integrated luminescence intensities of {sup 3}P{sub 0}→{sup 3}H{sub 4} transition (blue) to the {sup 3}P{sub 0}→{sup 3}F{sub 2} transition (red) of Pr{sup 3+} ions strongly depend on fluoride modifier BaF{sub 2} in glass composition. The luminescence bands of Pr{sup 3+} ions are shifted to shorter wavelengths with increasing BaF{sub 2} content. - Highlights: • Praseodymium doped lead-free germanate glasses modified by BaF{sub 2} were prepared. • Emission spectra correspond to transitions from {sup 3}P{sub 0} state to lower-lying states of Pr{sup 3+}. • The relative emission band intensities of Pr{sup 3+} depend strongly on BaF{sub 2} content. • Emission bands of Pr{sup 3+} are shifted to shorter wavelengths with increasing BaF{sub 2} content.

  12. High field-effect mobility at the (Sr,Ba)SnO{sub 3}/BaSnO{sub 3} interface

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Kohei, E-mail: kfujiwara@imr.tohoku.ac.jp; Nishihara, Kazuki; Shiogai, Junichi; Tsukazaki, Atsushi [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2016-08-15

    A perovskite oxide, BaSnO{sub 3}, has been classified as one of transparent conducting materials with high electron mobility, and its application for field-effect transistors has been the focus of recent research. Here we report transistor operation in BaSnO{sub 3}-based heterostructures with atomically smooth surfaces, fabricated on SrTiO{sub 3} substrates by the (Sr,Ba)SnO{sub 3} buffer technique. Indeed, modulation of band profiles at the channel interfaces with the insertion of wide bandgap (Sr,Ba)SnO{sub 3} as a barrier layer results in a significant improvement of field-effect mobility, implying effective carrier doping at the regulated heterointerface. These results provide an important step towards realization of high-performance BaSnO{sub 3}-based field-effect transistors.

  13. Optical characteristics of BaGa2S4:Ho3+ and BaGa2Se4:Ho3+ single crystals

    International Nuclear Information System (INIS)

    Choe, Sung-Hyu; Jin, Moon-Seog; Kim, Wha-Tek

    2005-01-01

    BaGa 2 S 4 , BaGa 2 S 4 :Ho 3+ , BaGa 2 Se 4 , and BaGa 2 Se 4 :Ho 3+ single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the single crystals were investigated in the temperature region from 11 K to 300 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Two broad emission bands were observed in the photoluminescence spectra of the single crystals. These bands were attributed to donor-acceptor pair recombinations. Sharp emission peaks were observed in the BaGa 2 S 4 :Ho 3+ and the BaGa 2 Se 4 :Ho 3+ single crystals and were assigned to radiation recombination between split Stark levels of Ho 3+ .

  14. Methodological Aspects of Architectural Documentation

    Directory of Open Access Journals (Sweden)

    Arivaldo Amorim

    2011-12-01

    Full Text Available This paper discusses the methodological approach that is being developed in the state of Bahia in Brazil since 2003, in architectural and urban sites documentation, using extensive digital technologies. Bahia has a vast territory with important architectural ensembles ranging from the sixteenth century to present day. As part of this heritage is constructed of raw earth and wood, it is very sensitive to various deleterious agents. It is therefore critical document this collection that is under threats. To conduct those activities diverse digital technologies that could be used in documentation process are being experimented. The task is being developed as an academic research, with few financial resources, by scholarship students and some volunteers. Several technologies are tested ranging from the simplest to the more sophisticated ones, used in the main stages of the documentation project, as follows: work overall planning, data acquisition, processing and management and ultimately, to control and evaluate the work. The activities that motivated this paper are being conducted in the cities of Rio de Contas and Lençóis in the Chapada Diamantina, located at 420 km and 750 km from Salvador respectively, in Cachoeira city at Recôncavo Baiano area, 120 km from Salvador, the capital of Bahia state, and at Pelourinho neighbourhood, located in the historic capital. Part of the material produced can be consulted in the website: < www.lcad.ufba.br>.

  15. Incorporation of Ba in Al and Fe pollucite

    Energy Technology Data Exchange (ETDEWEB)

    Vance, Eric R., E-mail: erv@ansto.gov.au [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232 (Australia); Gregg, Daniel J.; Griffiths, Grant J. [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232 (Australia); Gaugliardo, Paul R. [Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, WA 6009 (Australia); Grant, Charmaine [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232 (Australia)

    2016-09-15

    Ba, the transmutation product of radioactive Cs, can be incorporated at levels of up to ∼0.07 formula units in Cs{sub (1−2x)}Ba{sub x}AlSi{sub 2}O{sub 6} aluminium pollucite formed by sol-gel methods and sintering at 1400 °C, with more Ba forming BaAl{sub 2}Si{sub 2}O{sub 8} phases. The effect of Ba substitution in pollucite-structured CsFeSi{sub 2}O{sub 6} was also studied and no evidence of Ba substitution in the pollucite structure via cation vacancies or Fe{sup 2+} formation was obtained. The Ba entered a Fe-silicate glass structure. Charge compensation was also attempted with a Cs{sup +} + Fe{sup 3+} ↔ Ba{sup 2+} + Ni{sup 2+} scheme but again the Ba formed a glass and NiO was evident. PCT leaching data showed CsFeSi{sub 2}O{sub 6} to be very leach resistant. - Highlights: • Barium can be incorporated into aluminium pollucite. • Positron annihilation lifetime spectroscopy supports a charge vacancy mechanism of incorporation. • Iron pollucite does not appear to incorporate any barium with either vacancy or charge compensation mechanisms. • Leaching data suggest iron pollucite is very leach resistant.

  16. Submillimeter and microwave residual losses in epitaxial films of Y-Ba-Cu-O and Tl-Ca-Ba-Cu-O

    International Nuclear Information System (INIS)

    Miller, D.; Richards, P.L.; Eom, C.B.; Geballe, T.H.; Etemad, S.; Inam, A.; Venkatesan, T.; Martens, J.S.; Lee, W.Y.

    1992-12-01

    We have used a novel bolometric technique and a resonant technique to obtain accurate submillimeter and microwave residual loss data for epitaxial thin films of YBa 2 Cu 3 O 7 , Tl 2 Ca 2 Ba 2 Cu 3 O 10 and Tl 2 CaBa 2 Cu 2 O 8 . For all films we obtain good agreement between the submillimeter and microwave data, with the residual losses in both the Y-Ba-Cu-O and Tl-Ca-Ba-Cu-O films scaling approximately as frequency squared below ∼ 1 THz. We are able to fit the losses in the Y-Ba-Cu-O films to a two fluid and a weakly coupled grain model for the a-b planeconductivity, in good agreement with results from a Kramers-Kronig analysis of the loss data

  17. Processing of R-Ba-Cu-O superconductors

    International Nuclear Information System (INIS)

    Wu, H.

    1998-01-01

    Precipitation processes were developed to introduce second phases as flux pinning centers in Gd-Ba-Cu-O and Nd-Ba-Cu-O superconductors. In Gd-Ba-Cu-O, precipitation is caused by the decrease of the upper solubility limit of Gd 1+x Ba 2-x Cu 3 O 7 solid solution (Gd123ss) in low oxygen partial pressure. Processing of supersaturated Gd 1.2 Ba 1.8 Cu 3 O 7 in low oxygen partial pressure can produce dispersed second phases. Gd211 is formed as a separate phase while extensive Gd124 type stacking fault is formed instead of a separate CuO phase. As a result of the precipitation reaction, the transition temperature and critical current density are increased. In Nd-Ba-Cu-O, precipitation is caused by the decrease of the lower solubility limit of Nd 1+x Ba 2-x Cu 3 O 7 solid solution (Nd123ss) in oxygen. DTA results reveal the relative stability of Nd123ss in different oxygen partial pressures. In 1 bar oxygen partial pressure, Nd123ss with x = 0.1 is the most stable phase. In lower oxygen partial pressures, the most stable composition shifts towards the stoichiometric composition. The relative stability changes faster with decreasing oxygen partial pressure. Therefore, processing in oxygen and air tends to produce broad superconducting transitions but sharp transitions can be achieved in 0.01 bar and 0.001 bar oxygen partial pressures. While the lower solubility limits in 0.01 bar and 0.001 bar oxygen partial pressures remain at x = 0.00, the solubility limits in oxygen and air show a narrowing with decreasing temperature. Because of the narrowing of the solubility range in oxygen, oxygen annealing of Nd123 initially processed in low oxygen partial pressures will result in precipitation of second phases. The equilibrium second phase is BaCuO 2 for temperature above 608 C, and at lower temperatures the equilibrium second phases are Ba 2 CuO 3.3 and Ba 2 Cu 3 O 5+y . However, annealing at low temperature may produce a fine metastable transition phase. A coherent intermediate

  18. TRANSITIVITY AND THE BA CONSTRUCTION

    Directory of Open Access Journals (Sweden)

    Pei-Jung Kuo

    2010-06-01

    Full Text Available In this paper, I discuss the legitimacy of positing a Transitivity Projection (= TrP cf. Bowers 1993, 1997, 2001 and 2002 in the BA construction in Mandarin Chinese. BA has been proposed to be a semantically-bleached verb, inserted in the v position (Huang 1997 and Lin 2001. Several pieces of evidence such as manner adverbial placement (cf. Huang, Li and Li 2009 and GEI-insertion (cf. Tang 2001 indicate that there must be a functional projection between the vP and VP to host the BA NP. I propose that a TrP is probably the most apt candidate for the XP. I also argue, in contrast to the proposal by Huang, Li and Li (2009, that the present proposal which employs a TrP captures most of the properties of the BA construction. A comparison with the structure of the BEI construction also shows that the TrP proposal fits into the general picture of current linguistic theory on transitive constructions without extra stipulations.

  19. Structural evolution of Ba8Ti3Nb4O24 from BaTiO3 using a series of Ba(Ti1−5xNb4x)O3 solid solutions

    International Nuclear Information System (INIS)

    Barrientos Hernández, F.R.; Lira Hernández, I.A.; Gómez Yáñez, C.; Arenas Flores, A.; Cabrera Sierra, R.; Pérez Labra, M.

    2014-01-01

    Highlights: • The evolution phase Ba 8 Ti 3 Nb 4 O 24 was obtained through the mechanism Ba(Ti 1-5x Nb 4x )O 3 . • Addition of niobium can accelerate grain growth of BaTiO 3 ceramics. • Ba 8 Ti 3 Nb 4 O 24 presents a dielectric loss of 0.0035 and permittivity value of 54.6. • Electrical measurements showed that Nb 5+ content drops Curie temperature. • Samples with x ⩾ 0.0625 shows an insulating behavior. -- Abstract: In this work, the structural evolution of hexagonal phase Ba 8 Ti 3 Nb 4 O 24 by adding Nb 2 O 5 to perovskite structure of BaTiO 3 was investigated. The compositions Ba(Ti 1-5x Nb 4x )O 3 ceramics, with 0.00025 ⩽ x ⩽ 0.125 were prepared by the conventional solid state route in air atmosphere, the powders precursors, BaTiO 3 , BaCO 3 and Nb 2 O 5 , were mixed in stoichiometric proportions and ground in a ball mill using alumina balls and acetone. The mixed powders were calcined at temperatures up to 1500 °C. The phase transformation of Ba 8 Ti 3 Nb 4 O 24 from BaTiO 3 was studied by DRX, Raman spectroscopy, SEM, electrical measurements (relative permittivity and P–E hysteresis loops); Rietveld’s refinement was used to structurally characterize the samples. For the devices obtained capacitance was measured at 1 kHz; with these values we calculated the relative permittivity. The samples show typical P–E hysteresis loops at room temperature accompanied by saturation polarization (Ps) and remnant polarization (Pr). The DRX and Rietveld’s refinement results show x ⩽ 0.01 has a ferroelectric behavior. When the doped level is increased x ⩾ 0.02, a peak displacement is observed, this is due to the phase transformation of tetragonal to cubic into the unit cell. Finally, with x = 0.125 the crystal structure transforms to the characteristic hexagonal phase Ba 8 Ti 3 Nb 4 O 24 which resonates at microwave frequencies

  20. Separation of Sr from Ca, Ba and Ra by means of Ca(OH)2 and Ba(Ra)Cl2 or Ba(Ra)SO4 for the determination of radiostrontium

    DEFF Research Database (Denmark)

    Chen, Q.J.; Hou, Xiaolin; Yu, Y.X.

    2002-01-01

    be completed. The new separation procedure has been successfully used for the determination of Sr-90 in samples with high Ca content, such as 451 of seawater and 2001 of drinking water. The analytical quality of the results is comparable to that of the traditional method using fuming nitric acid and BaCrO4......A simple procedure is developed to separate Sr from a large amount of Ca, which relies on the insolubility of Ca(OH)(2) in alkaline solution. Calcium is quantitatively separated from Sr and more than 95% of Sr is recovered from a sample with as much as 50 g of Ca and a Ca/Sr mole ratio of 250....... A new procedure for the separation of Sr from Ba and Ra is also investigated, which is based on the difference in solubility of the chlorides of Sr, Ba and Ra in HCl media. In 9.5 mol 1(-1) HCl or 7.5 mol 1(-1) HCl-10% acetone media, >97% of Ba and Ra can be removed by Ba(Ra)Cl-2 precipitation, and >94...

  1. Characterization and dielectric properties of BaTiO3 prepared from Ba(NO3)2-TiO2 mixture

    International Nuclear Information System (INIS)

    Othman, K.I.; Hassan, A.A.; Ali, M.E.; Abdelal, O.A.; Salah El Dien, F.E.; El-Raghy, S.M.; Abdel-Karim, R.

    2012-01-01

    BaTiO 3 powder was prepared through a solid-state reaction between the Ba(NO 3 ) 2 and TiO 2 . The thermal analysis and XRD techniques were used to study its formation. A single phase BaTiO 3 was formed after calcination at 600 degree C for 6 hrs. The dielectric properties of the sintered BaTiO 3 were determined in the temperature range from room temperature to 20 degree C at a frequency ranging from 500 Hz to 100 khz. The relative permittivity and the dielectric loss of the sintered pellets at 1 khz, measured at room temperature,were 1805 and 0.419 respectively.

  2. Synthesis, crystal structure and electrical properties of A-site cation ordered BaErMn2O5 and BaErMn2O6

    International Nuclear Information System (INIS)

    Świerczek, Konrad; Klimkowicz, Alicja; Zheng, Kun; Dabrowski, Bogdan

    2013-01-01

    In this paper, we report on a synthesis procedure, structural and electrical properties of BaErMn 2 O 5 and BaErMn 2 O 6 , A-site double perovskites having layered arrangement of Ba and Er cations. These materials belong to a family of BaLnMn 2 O 5+δ oxides, which up to now were successfully synthesized for Ln=Y and La–Ho lanthanides. Up to our knowledge, this is the first report on the successful synthesis of BaErMn 2 O 5 and BaErMn 2 O 6 , yielding>95 wt% of the considered compounds. Structural characterization of the materials is given at room temperature, together with in situ XRD studies, performed during oxidation of BaErMn 2 O 5 in air, at elevated temperatures up to 500 °C. A complex structural behavior was observed, with oxidation process of BaErMn 2 O 5 occurring at around 300 °C. The oxidized BaErMn 2 O 6 shows a structural phase transition at about 225 °C. Results of structural studies are supported by thermogravimetric measurements of the oxidation process, performed in air, as well as reduction process, preformed in 5 vol% of H 2 in Ar. Additionally, isothermal oxidation/reduction cycles were measured at 500 °C, showing interesting properties of BaErMn 2 O 5+δ , from a point of view of oxygen storage technology. Electrical conductivity of BaErMn 2 O 5 is of the order of 10 −4 S cm −1 at room temperature and shows activated character on temperature with activation energy E a =0.30(1) eV. Positive sign of Seebeck coefficient for this material indicates holes as dominant charge carriers. Oxidized BaErMn 2 O 6 possesses much higher electrical conductivity, almost 0.2 S cm −1 at room temperature. Additional, about 10-fold increase of electrical conductivity, occurring in the vicinity of 225 °C for this material, can be associated with phase transition from charge/orbital-ordered insulator COI(CE) to paramagnetic metal PM phase. The highest conductivity for BaErMn 2 O 6 was measured near 500 °C and is almost equal to 40 S cm −1 , while

  3. Revisiting the BaO2/BaO redox cycle for solar thermochemical energy storage.

    Science.gov (United States)

    Carrillo, A J; Sastre, D; Serrano, D P; Pizarro, P; Coronado, J M

    2016-03-21

    The barium peroxide-based redox cycle was proposed in the late 1970s as a thermochemical energy storage system. Since then, very little attention has been paid to such redox couples. In this paper, we have revisited the use of reduction-oxidation reactions of the BaO2/BaO system for thermochemical heat storage at high temperatures. Using thermogravimetric analysis, reduction and oxidation reactions were studied in order to find the main limitations associated with each process. Furthermore, the system was evaluated through several charge-discharge stages in order to analyse its possible degradation after repeated cycling. Through differential scanning calorimetry the heat stored and released were also determined. Oxidation reaction, which was found to be slower than reduction, was studied in more detail using isothermal tests. It was observed that the rate-controlling step of BaO oxidation follows zero-order kinetics, although at high temperatures a deviation from Arrhenius behaviour was observed probably due to hindrances to anionic oxygen diffusion caused by the formation of an external layer of BaO2. This redox couple was able to withstand several redox cycles without deactivation, showing reaction conversions close to 100% provided that impurities are previously eliminated through thermal pre-treatment, demonstrating the feasibility of this system for solar thermochemical heat storage.

  4. Synthesis and characterization of BaTiO3 ferroelectric material

    International Nuclear Information System (INIS)

    Osman, K.I.

    2011-01-01

    BaTiO 3 powder was prepared at low temperatures using the solid-state reaction, starting with two different precursors; the BaCO 3 /TiO 2 and the Ba(NO 3 ) 2 /TiO 2 powder mixtures. It was found that, a single phase BaTiO 3 was formed after calcination at 750 degree C for 10 h and at 600 degree C for 6 h for the first and second mixtures, respectively. Thermal and XRD analyses were used to study the formation kinetics of BaTiO 3 . Contracting volume reaction model was found to control both reactions. The SEM of the as milled powder, TMA, TG and thermodynamics analysis have been used to propose a realistic approach describing the reaction mechanism of BaTiO 3 . Characterization and the dielectric properties of the sintered BaTiO 3 were investigated. The relative permittivity and the dielectric loss measured at room temperature and at 1 khz were 2028.5 and 0.043 for BaTiO 3 prepared from BaCO 3 /TiO 2 , while they were 1805.33 and 0.41 for BaTiO 3 prepared from Ba(NO 3 ) 2 /TiO 2 .

  5. Experimental investigation of decay properties of neutron deficient $^{116-118}$Ba isotopes and test of $^{112-115}$Ba beam counts

    CERN Multimedia

    We propose to study decay of neutron deficient isotopes $^{116-118}$Ba using Double Sided Silicon Strip Detector (DSSSD). To study delayed-proton and $\\alpha$-decay branching ratios of $^{116-118}$Ba are of special interest because of their vicinity to the proton drip line. The nuclear life-times and properties of the proton unstable states of Cs isotopes, populated through decay of $^{116-118}$Ba isotopes will be measured. In addition to that we propose beam development of $^{112-115}$Ba to study exotic decay properties of these neutron deficient nuclei and to search for super-allowed $\\alpha$-decay in future.

  6. Enhanced 77 K vortex-pinning in Y Ba2Cu3O7−x films with Ba2Y TaO6 and mixed Ba2Y TaO6 + Ba2Y NbO6 nano-columnar inclusions with irreversibility field to 11 T

    Directory of Open Access Journals (Sweden)

    F. Rizzo

    2016-06-01

    Full Text Available Pulsed laser deposited thin Y Ba2Cu3O7−x (YBCO films with pinning additions of 5 at. % Ba2Y TaO6 (BYTO were compared to films with 2.5 at. % Ba2Y TaO6 + 2.5 at. % Ba2Y NbO6 (BYNTO additions. Excellent magnetic flux-pinning at 77 K was obtained with remarkably high irreversibility fields greater than 10 T (YBCO-BYTO and 11 T (YBCO-BYNTO, representing the highest ever achieved values in YBCO films.

  7. (Ba+Sr)/Ti ratio dependence of the dielectric properties for (Ba0.5Sr0.5)TiO3 thin films prepared by ion beam sputtering

    Science.gov (United States)

    Yamamichi, Shintaro; Yabuta, Hisato; Sakuma, Toshiyuki; Miyasaka, Yoichi

    1994-03-01

    (Ba0.5Sr0.5)TiO3 thin films were prepared by ion beam sputtering from powder targets with (Ba+Sr)/Ti ratios ranging from 0.80 to 1.50. All of the perovskite (Ba,Sr)TiO3 films were single phase except for the film with a (Ba+Sr)/Ti ratio of 1.41. The dielectric constant values notably depended on the (Ba+Sr)/Ti ratio for films thicker than 70 nm. The highest dielectric constant of 580 was achieved for the 5% (Ba+Sr) rich film. This (Ba+Sr)/Ti ratio dependence was diminished by the thickness dependence for thinner films. The grain sizes for the 9% (Ba+Sr) rich film and for the 6% (Ba+Sr) poor film ranged from 70 to 100 nm and from 30 to 60 nm, respectively. This grain size difference could explain why slightly A-site rich (Ba,Sr)TiO3 films have a larger dielectric constant than A-site poor films.

  8. Structural and thermodynamic characterization of the perovskite-related BA{sub 1+y}UO{sub 3+x} and (BA,SR){sub 1+y}UO{sub 3+x} phases

    Energy Technology Data Exchange (ETDEWEB)

    Cordfunke, E.H.P. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Booij, A.S. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Smit-Groen, V. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Vlaanderen, P. van [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); IJdo, D.J.W. [Rijksuniversiteit Leiden (Netherlands). Gorlaeus Labs.

    1996-11-01

    The perovskite-type BaUO{sub 3} structure has been investigated by X-ray and neutron diffraction. The Ba/U ratio, the (Ba, Sr)/U ratio, and the oxygen stoichiometry in Ba{sub 1+y}UO{sub 3+x} were varied, and the integral enthalpies of formation determined by solution calorimetry. In addition, equilibrium oxygen partial pressures were measured using a reversible EMF cell. The chemical defect mechanism is discussed, and it is shown that a continuous series BaUO{sub 3}-Ba{sub 1+y}UO{sub 3+x}-Ba{sub 3}UO{sub 6} exist in which uranium vacancies are gradually filled up with barium ions, whereas uranium is oxidized via the pentavalent to the hexavalent state in Ba{sub 3}UO{sub 6}(=Ba{sub 2}(Ba, U)O{sub 6}). (orig.).

  9. Dynamics of photoexcited Ba+ cations in 4He nanodroplets

    International Nuclear Information System (INIS)

    2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" >Leal, Antonio; 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" >Pi, Martí; Zhang, Xiaohang; Drabbels, Marcel; 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France))" >Barranco, Manuel; Cargnoni, Fausto; Hernando, Alberto; Mateo, David; Mella, Massimo

    2016-01-01

    We present a joint experimental and theoretical study on the desolvation of Ba + cations in 4 He nanodroplets excited via the 6p ← 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba + cations and Ba + He n exciplexes with n = 1 and 2. The speed distributions of the ions are well described by Maxwell-Boltzmann distributions with temperatures ranging from 60 to 178 K depending on the excitation frequency and Ba + He n exciplex size. These results have been analyzed by calculations based on a time-dependent density functional description for the helium droplet combined with classical dynamics for the Ba + . In agreement with experiment, the calculations reveal the dynamical formation of exciplexes following excitation of the Ba + cation. In contrast to experimental observation, the calculations do not reveal desolvation of excited Ba + cations or exciplexes, even when relaxation pathways to lower lying states are included.

  10. The interaction of NO2 with BaO: from cooperative adsorption to Ba(NO3)2 formation

    International Nuclear Information System (INIS)

    Yi, Cheol-Woo W.; Kwak, Ja Hun H.; Szanyi, Janos

    2007-01-01

    The effect of water on the morphology of BaO/Al2O3-based NOx storage materials was investigated using Fourier transform infrared spectroscopy, temperature programmed desorption, and time-resolved synchrotron X-ray diffraction techniques. The results of this multi-spectroscopy study reveal that, in the presence of water, surface Ba-nitrates convert to bulk nitrates, and water facilitates the formation of large Ba(NO3)2 particles. The conversion of surface to bulk Ba-nitrates is completely reversible, i.e. after the removal of water from the storage material a significant fraction of the bulk nitrates re-convert to surface nitrates. NO2 exposure of a H2O-containing (wet) BaO/Al2O3 sample results in the formation of nitrites and bulk nitrates exclusively, i.e. no surface nitrates form. After further exposure to NO2, the nitrites completely convert to bulk nitrates. The amount of NOx taken up by the storage material is, however, essentially unaffected by the presence of water, regardless of whether the water was dosed prior to or after NO2 exposure. Based on the results of this study we are now able to explain most of the observations reported in the literature on the effect of water on NOx uptake on similar storage materials

  11. Growth of BaSi2 continuous films on Ge(111) by molecular beam epitaxy and fabrication of p-BaSi2/n-Ge heterojunction solar cells

    Science.gov (United States)

    Takabe, Ryota; Yachi, Suguru; Tsukahara, Daichi; Toko, Kaoru; Suemasu, Takashi

    2017-05-01

    We grew BaSi2 films on Ge(111) substrates by various growth methods based on molecular beam epitaxy (MBE). First, we attempted to form BaSi2 films directly on Ge(111) by MBE without templates. We next formed BaSi2 films using BaGe2 templates as commonly used for MBE growth of BaSi2 on Si substrates. Contrary to our prediction, the lateral growth of BaSi2 was not promoted by these two methods; BaSi2 formed not into a continuous film but into islands. Although streaky patterns of reflection high-energy electron diffraction were observed inside the growth chamber, no X-ray diffraction lines of BaSi2 were observed in samples taken out from the growth chamber. Such BaSi2 islands were easily to get oxidized. We finally attempted to form a continuous BaSi2 template layer on Ge(111) by solid phase epitaxy, that is, the deposition of amorphous Ba-Si layers onto MBE-grown BaSi2 epitaxial islands, followed by post annealing. We achieved the formation of an approximately 5-nm-thick BaSi2 continuous layer by this method. Using this BaSi2 layer as a template, we succeeded in forming a-axis-oriented 520-nm-thick BaSi2 epitaxial films on Ge substrates, although (111)-oriented Si grains were included in the grown layer. We next formed a B-doped p-BaSi2(20 nm)/n-Ge(111) heterojunction solar cell. A wide-spectrum response from 400 to 2000 nm was achieved. At an external bias voltage of 1 V, the external quantum efficiency reached as high as 60%, demonstrating the great potential of BaSi2/Ge combination. However, the efficiency of a solar cell under AM1.5 illumination was quite low (0.1%). The origin of such a low efficiency was examined.

  12. Jungermanniales (Marchantiophyta da Chapada da Ibiapaba, Ceará, Brasil Jungermanniales (Marchantiophyta of the Ibiapaba Plateau, Ceará state, Brazil

    Directory of Open Access Journals (Sweden)

    Hermeson Cassiano de Oliveira

    2009-12-01

    Full Text Available A Chapada da Ibiapaba, localiza-se ao norte do estado do Ceará, possuindo uma extensão de 110 km com alitudes variando entre 800 e 1100 m. No inventário florístico de briófitas realizado na área, foram encontradas 15 espécies de hepáticas folhosas, pertencentes a odaem Jungermanniales, distribuídas em oito gêneros e seis famílias. Das espécies encontradas, cinco representam novos registros para o estado do Ceará e quatro para a região Nordeste. Chiloscyphus serratus (Mitt. J.J. Engel & R.M. Schust. é citada pela segunda vez para o Brasil. São fornecidos chaves de identificação para as famílias e espécies, distribuição geográfica, comentários referentes à ambiente, substratos e caracteres taxonômicos pertinentes, além de ilustração para Heteroscyphus contortuplicatus (Nees & Mont. Grolle.The Ibiapaba Plateau, north zone of Ceara, Brazil, has a length of 110 km with altitudes between 800 and 1.100 m. In the bryophytes floristic survey conducted in the area, 15 species of liverworts were found, wich belong to the order Jungermanniales, distributed in eight genera and six families. Among the species found, five represent new records for the state of Ceara and four for the Northeast region. Chiloscyphus serratus (Mitt. J.J. Engel & R.M. Schust. is cited by the second time for Brazil. Identification keys to the families and species, geographic distribution, comments on the environment, substrate and important taxonomic characters are provided for the species found. An Illustration has been made for Heteroscyphus contortuplicatus (Nees & Mont. Grolle.

  13. Laserspectroscopic studies of collective properties of neutron deficient Ba nuclei

    International Nuclear Information System (INIS)

    Bekk, K.; Andl, A.; Goering, S.; Hanser, A.; Nowicki, G.; Rebel, H.; Schatz, G.

    1979-01-01

    Isotope shifts and hyperfine structure of the BaI resonance-line (lambda=553.6 nm) have been measured by dye laser induced resonance fluorescence on an atomic beam for sup(135m,129g,129m,126) Ba thus extending previous high resolution measurements of neutron deficient Ba nuclides (N - isomers sup(135m) Ba and sup(135m) Ba show a decreased staggering. Conspicuously the isomer shift of the g 7/2 + isomer sup(129m) Ba proves to be negative. The nuclear structure information is discussed in the context of gamma-spectroscopic studies of transitional nuclei with 50 [de

  14. Decrease in electrical contact resistance of Sb-doped n+-BaSi2 layers and spectral response of an Sb-doped n+-BaSi2/undoped BaSi2 structure for solar cells

    Science.gov (United States)

    Kodama, Komomo; Takabe, Ryota; Yachi, Suguru; Toko, Kaoru; Suemasu, Takashi

    2018-03-01

    We investigated how the electron concentration n in a 300-nm-thick Sb-doped n+-BaSi2 layer grown by molecular beam epitaxy affected the contact resistance R C to surface electrodes (Al, indium-tin-oxide). As the n of n-BaSi2 increased, R C decreased and reached a minimum of 0.019 Ω cm2 at n = 2.4 × 1018 cm-3 for the Al electrodes. This value was more than 1 order of magnitude smaller than that obtained for Al/B-doped p-BaSi2. We believe that this significant decrease in R C came from Sb segregation. Furthermore, the internal quantum efficiency (IQE) spectrum was evaluated for an Sb-doped n+-BaSi2 (20 nm)/undoped BaSi2 (500 nm)/n+-Si(111) structure. Its IQE reached as high as ˜50% over a wide wavelength range under a small bias voltage of 0.1 V applied between the top and bottom electrodes.

  15. Phase relationships in the BaO-Ga2O3-Ta2O5 system and the structure of Ba6Ga21TaO40.

    Science.gov (United States)

    Cao, Jiang; Yu, Xiaodi; Kuang, Xiaojun; Su, Qiang

    2012-07-16

    Phase relationships in the BaO-Ga(2)O(3)-Ta(2)O(5) ternary system at 1200 °C were determined. The A(6)B(10)O(30) tetragonal tungsten bronze (TTB) related solution in the BaO-Ta(2)O(5) subsystem dissolved up to ~11 mol % Ga(2)O(3), forming a ternary trapezoid-shaped TTB-related solid solution region defined by the BaTa(2)O(6), Ba(1.1)Ta(5)O(13.6), Ba(1.58)Ga(0.92)Ta(4.08)O(13.16), and Ba(6)GaTa(9)O(30) compositions in the BaO-Ga(2)O(3)-Ta(2)O(5) system. Two ternary phases Ba(6)Ga(21)TaO(40) and eight-layer twinned hexagonal perovskite solid solution Ba(8)Ga(4-x)Ta(4+0.6x)O(24) were confirmed in the BaO-Ga(2)O(3)-Ta(2)O(5) system. Ba(6)Ga(21)TaO(40) crystallized in a monoclinic cell of a = 15.9130(2) Å, b = 11.7309(1) Å, c = 5.13593(6) Å, β = 107.7893(9)°, and Z = 1 in space group C2/m. The structure of Ba(6)Ga(21)TaO(40) was solved by the charge flipping method, and it represents a three-dimensional (3D) mixed GaO(4) tetrahedral and GaO(6)/TaO(6) octahedral framework, forming mixed 1D 5/6-fold tunnels that accommodate the Ba cations along the c axis. The electrical property of Ba(6)Ga(21)TaO(40) was characterized by using ac impedance spectroscopy.

  16. Ruthenium perovskites of type Ba/sub 2/BRuO/sub 6/ and Ba/sub 3/BRu/sub 2/O/sub 9/ with B = indium, rhodium

    Energy Technology Data Exchange (ETDEWEB)

    Schaller, H U; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1981-02-01

    The black perovskites Ba/sub 2/InRu/sup 5 +/O/sub 6/ and Ba/sub 3/InRu/sub 2/O/sub 9/ (mean oxydation state of ruthenium: +4.5) adopt the hexagonal BaTiO/sub 3/ structure and form a continuous series of mixed crystals. According to the intensity calculations and analysis of the vibrational spectroscopic data an ordered distribution between indium and ruthenium is present: 1:1 order in Ba/sub 2/RuO/sub 6/ (space group P-3m1 respective Dsub(3d)/sup 3/; R' = 5.3%); 1:2 order in Ba/sub 3/InRu/sub 2/O/sub 9/ (space group P6/sub 3//mmc respective Dsub(6h)/sup 4/; R' = 4.6%). The corresponding black Rh compounds, Ba/sub 2/RhRuO/sub 6/ and Ba/sub 3/RhRu/sub 2/O/sub 9/, crystallize in the rhombohedral 9 L type of BaRuO/sub 3/ (author).

  17. DINÂMICA DA FLORA ARBUSTIVO-ARBÓREA COLONIZADORA EM UMA ÁREA DEGRADADA PELA EXTRAÇÃO DE OURO EM DIAMANTINA, MG

    Directory of Open Access Journals (Sweden)

    Wander Gladson Amaral

    2013-01-01

    Full Text Available The main goal was to understand the dynamic process of vegetation colonizing an area degraded by the extraction of gold. The study area was stratified into three environments and, in each environment, contiguous ten plots of 100m 2 each were allocated. For the realization of the dynamics, two surveys of shrub-tree with level of inclusion (DAS30 > 3 cm were carried out. The first one was realized in 2008 and second in 2010. In 2010, the new individuals that met the criterion for inclusion (recruits were marked and measured, the dead registered and the survivors were measured again. The rates of mortality, recruitment, gain and loss in basal area of each environment were calculated and it became evident the importance of dynamics as a tool to help understand the relationships of ecological succession of species. The Shannon diversity index among the three environments were compared by t-test of Hutcheson and it was used the analysis of indicator species to determine species preferences of each of the three pre-determined environments.The total number of individuals passed of 707 to 909 in two years of interval, reinforcing the importance of natural regeneration processes of ecological succession. The environment II remained the most abundant one despite it presented a high mortality rate, which can be explained by the high rate of recruitment. The species Eremanthus incanus, Trembleya laniflora, Trembleya parviflora, Roupala montana, Coccoloba brasiliensis and Tibouchina candoleana, presented higher importance of value in the two surveys, showing superiority in the colonization of the area degraded by the extraction of gold and could be indicated in programs for the recuperation of degraded areas that are in similar conditions in the region of Diamantina municipality.

  18. Scintillation and radiation damage of doped BaF2 crystals

    International Nuclear Information System (INIS)

    Gong Zufang; Xu Zizong; Chang Jin

    1992-01-01

    The emission spectra and the radiation damage of BaF 2 crystals doped Ce and Dy have been studied. The results indicate that the doped BaF 2 crystals have the intrinsic spectra of impurity besides the intrinsic spectra of BaF 2 crystals. The crystals colored and the transmissions decrease with the concentration of impurity in BaF 2 crystals after radiation by γ-ray of 60 Co. The doped Ce BaF 2 irradiated by ultraviolet has faster recover of transmissions but for doped Dy the effect is not obvious. The radiation resistance is not good as pure BaF 2 crystals

  19. Chemiluminescence from the reaction of Ba 3D with nitric oxide

    International Nuclear Information System (INIS)

    Johnson, S.A.; Solarz, R.W.; Dubrin, J.W.; Brotzmann, R.

    1977-01-01

    The reaction of laser excited Ba*( 3 D) states with nitric oxide is presented. BaO product is not detected, although the channel is thermodynamically open, and instead chemiluminescence is observed. Experiments which suggest that radiative recombination, Ba + NO → BaNO* → BaNO, is the observed reaction channel will also be presented

  20. Thermoelectric properties of doped BaHfO_3

    International Nuclear Information System (INIS)

    Dixit, Chandra Kr.; Bhamu, K. C.; Sharma, Ramesh

    2016-01-01

    We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO_3 by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO_3 doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. The doped BaHfO_3 is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO_3 is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.

  1. Crystal structure of a new natural (Ba, Nb) silicate

    International Nuclear Information System (INIS)

    Yamnova, N.A.; Pushcharovskii, D.Yu.; Voloshin, A.V.

    1990-01-01

    The structure of a new mineral Ba 3 (Ti 1.2 Nb 4.8 ) Si 4 O 25.4 is determined (166 reflections, method of least squares in anisotropic approximation, R = 0.040). The crystallographic parameters are: a = 9.03(1), c = 7.868(6) angstrom, Z = 1, space group P anti 62m. Like the previously investigated synthetic analogs Ba 3 Si 4 Nb 6 O 26 , Ba 3 Si 4 Ti 6 O 23 , and Ba 3 Si 4 Ta 6 O 26 , the structure contains a mixed framework of octahedral columns of triangular section, bound to the diortho groups [Si 2 O 7 ], of which the cavities contain the Ba atoms

  2. AHP 45: REVIEW: PHYUR BA

    Directory of Open Access Journals (Sweden)

    'Brug mo skyid འབྲུག་མོ་སྐྱིད། (Zhoumaoji 周毛吉

    2017-03-01

    Full Text Available Mkha' mo rgyal was born in Dgon gong ma Village, 'Ba' (Tongde County, Mtsho lho (Hainan Tibetan Autonomous Prefecture, Mtsho sngon (Qinghai Province. While attending the Tibetan Studies College of Mtsho sngon Nationalities University she began writing. In addition to editing and translating teaching materials for primary and secondary schools, she has also published short stories and poetry (Mkha' mo rgyal, 2015. Phyur ba is the first Tibetan women's novel (Robin 2016:86 and was recognized as an Outstanding Work by the Qinghai Writers Guild in 2014 (Duojiecairang and Limaoyou 2014. 1 The name, which translates as 'dried cheese' is a food eaten daily by many Tibetans. Made from fermented milk without cream, it is dried in the sun by women in pastoral areas. Both sweet and sour, phyur ba brings to mind the happiness and sadness, ups and downs, laughter and tears that life brings. ...

  3. High-pressure BaCrO_3 polytypes and the 5H–BaCrO_2_._8 phase

    International Nuclear Information System (INIS)

    Arévalo-López, Angel M.; Paul Attfield, J.

    2015-01-01

    Polytypism of BaCrO_3 perovskites has been investigated at 900–1100 °C and pressures up to 22 GPa. Hexagonal 5H, 4H, and 6H perovskites are observed with increasing pressure, and the cubic 3C perovskite (a=3.99503(1) Å) is observed in bulk form for the first time at 19–22 GPa. An oxygen-deficient material with limiting composition 5H–BaCrO_2_._8 is synthesised at 1200 °C under ambient pressure. This contains double tetrahedral Cr"4"+ layers and orders antiferromagnetically below 260 K with a (0 0 1/2) magnetic structure. - Graphical abstract: Hexagonal 5H, 4H, and 6H perovskites polytypes of BaCrO_3 are observed with increasing pressure and the cubic 3C perovskite is stabilised in bulk form for the first time at 19–22 GPa. Oxygen-deficient 5H–BaCrO_2_._8 synthesised at ambient pressure contains double tetrahedral Cr"4"+ layers and orders antiferromagnetically below 260 K with a (0 0 1/2) magnetic structure.

  4. Tipificação e Análise de Sustentabilidade em Sistemas Agrícolas Familiares no Distrito de Água Fria, Chapada dos Guimarães, Mato Grosso

    Directory of Open Access Journals (Sweden)

    Aldo Assunção da Cunha

    2011-04-01

    Full Text Available Este artigo tipifica e analisa 25 sistemas agrícolas familiares em propriedades de até 100 ha no Distrito de Água Fria, Município de Chapada dos Guimarães, Mato Grosso. Foram definidos 49 indicadores, entre originais e categorizados, em torno de 4 grupos de variáveis: uso e conservação de recursos naturais, sustentabilidade econômica, uso e potencial do horto e apoio institucional. A técnica de análise de agrupamento (clusters, aplicada a estas variáveis, permitiu a tipificação de 4 grupos de sistemas agrícolas distintos, validados pela abordagem sistêmica, caracterizando-se cada um deles em função das atividades mais importantes (subsistemas ou componentes, tais como: a criação extensiva de bovinos associada a propriedades com maiores áreas; atividade de indústria caseira, relacionada ao reduzido tamanho de área; área de lavoura mais importante em explorações; e regulamentação de posses mais recentes e maior diversificação de espécies plantadas no horto.

  5. Biodistribution and Radiation Dosimetry of the Integrin Marker 64Cu-BaBaSar-RGD2 Determined from Whole-Body PET/CT in a Non-Human Primate

    Science.gov (United States)

    Liu, Shuanglong; Vorobyova, Ivetta; Park, Ryan; Conti, Peter S.

    2017-10-01

    Introduction: 64Cu-BaBaSar-RGD2 is a positron emission radiotracer taken up by integrin αvβ3, which is overexpressed in many malignancies. The aim of this study was to evaluate the biodistribution of 64Cu-BaBaSar-RGD2 in a non-human primate with positron emission tomography and to estimate the absorbed doses in major organs for human. Materials and methods: Whole-body PET imaging was done in a Siemens Biograph scanner in a male macaque monkey. After an i.v. injection of 13.1–19.7 MBq/kg of 64Cu-BaBaSar-RGD2, whole body scan was collected for a total duration of 180 min. Attenuation and scatter corrections were applied to reconstruction of the whole-body emission scan. After image reconstruction, three-dimensional volumes of interest (VOI) were hand-drawn on the PET transaxial or coronal slices of the frame where the organ was most conspicuous. Time-activity curves for each VOI were obtained, and residence time of each organ was calculated by integration of the time-activity curves. Human absorbed doses were estimated using the standard human model in OLINDA/EXM software. Results: Injection of 64Cu-BaBaSar-RGD2 was well tolerated in the macaque monkey, with no serious tracer-related adverse events observed. 64Cu-BaBaSar-RGD2 was cleared rapidly from the blood pool, with a 12.1-min biological half-time. Increased 64Cu-BaBaSar-RGD2 uptake was observed in the kidneys, and bladder, with mean percentage injected dose (ID%) values at 1 h after injection approximately 35.50 ± 6.47 and 36.89 ± 5.48, respectively. The calculated effective dose was 15.30 ± 2.21 µSv/MBq, and the kidneys had the highest absorbed dose at 108.43 ± 16.41 µGy/MBq using the non-voiding model. For an injected activity of 925 MBq 64Cu for human, the effective dose would be 14.2 ± 2.1 mSv. Discussion: Due to the limitation of the monkey number, we evaluated 64Cu-BaBaSar-RGD2 in the same monkey of three imaging sessions. Measured absorbed doses and effective doses of 64Cu-BaBaSar-RGD2 are

  6. An approach to WWER fuels with BaCo

    International Nuclear Information System (INIS)

    Marino, A.; Demarco, G.

    2008-01-01

    BaCo is a code for the simulation of the behaviour of a nuclear fuel rod under operation conditions. BaCo, a quasi 2D code based on a finite differences scheme, has been used for simulating PHWR, CANDU, PWR, BWR, MOX, WWER, and experimental fuel rods. We improve the performance of BaCo with a set of tools based on the method of finite elements for 3D analysis of the stress-strain state. We can simulate any UO 2 pellet geometry. Standard WWER-440 fuel assemblies irradiated in the Kola-3 reactor of the CRP FUMEX II of the IAEA were the first WWER simulations with BaCo. We find a very good agreement among our calculations, the experimental results and other qualified fuel codes. We present the BaCo code and our results for PWR and WWER fuels of the CRP FUMEX II, the 3D analysis of WWER fuel pellet and the projections of these results with the Argentinean nuclear fuels development. (authors)

  7. Three new chalcohalides, Ba4Ge2PbS8Br2, Ba4Ge2PbSe8Br2 and Ba4Ge2SnS8Br2: Syntheses, crystal structures, band gaps, and electronic structures

    International Nuclear Information System (INIS)

    Lin, Zuohong; Feng, Kai; Tu, Heng; Kang, Lei; Lin, Zheshuai; Yao, Jiyong; Wu, Yicheng

    2014-01-01

    Highlights: • Three new chalcohalides: Ba 4 Ge 2 PbS 8 Br 2 , Ba 4 Ge 2 PbSe 8 Br 2 and Ba 4 Ge 2 SnS 8 Br 2 have been synthesized. • The MQ 5 Br octahedra and GeQ 4 tetrahedra form a three-dimensional framework with Ba 2+ in the channels. • Band Gaps and electronic structures of the three compounds were studied. - Abstract: Single crystals of three new chalcohalides: Ba 4 Ge 2 PbS 8 Br 2 , Ba 4 Ge 2 PbSe 8 Br 2 and Ba 4 Ge 2 SnS 8 Br 2 have been synthesized for the first time. These isostructural compounds crystallize in the orthorhombic space group Pnma. In the structure, the tetra-valent Ge atom is tetrahedrally coordinated with four Q (Q = S, Se) atoms, while the bi-valent M atom (M = Pb, Sn) is coordinated with an obviously distorted octahedron of five Q (Q = S, Se) atoms and one Br atom, showing the stereochemical activity of the ns 2 lone pair electron. The MQ 5 Br (M = Sn, Pb; Q = S, Se) distorted octahedra and the GeQ 4 (Q = S, Se) tetrahedra are connected to each other to form a three-dimensional framework with channels occupied by Ba 2+ cations. Based on UV–vis–NIR spectroscopy measurements and the electronic structure calculations, Ba 4 Ge 2 PbS 8 Br 2 , Ba 4 Ge 2 PbSe 8 Br 2 and Ba 4 Ge 2 SnS 8 Br 2 have indirect band gaps of 2.054, 1.952, and 2.066 eV respectively, which are mainly determined by the orbitals from the Ge, M and Q atoms (M = Pb, Sn; Q = S, Se)

  8. Intermetallic and metal-rich phases in the system Li-Ba-In-N

    International Nuclear Information System (INIS)

    Smetana, Volodymyr; Vajenine, Grigori V.; Kienle, Lorenz; Duppel, Viola; Simon, Arndt

    2010-01-01

    Three new intermetallic phases, BaLi 2.1 In 1.9 , BaLi 1.12 In 0.98 , and BaLi 1.06 In 1.16 and two subnitrides Li 35 In 45 Ba 39 N 9 and LiIn 2 Ba 3 N 0.83 have been synthesized and their crystal structures have been determined. According to single crystal X-ray diffraction data BaLi 2.1 In 1.9 and BaLi 1.12 In 0.98 crystallize with hexagonal symmetry (BaLi 2.1 In 1.9 : P6 3 /mmc, a=10.410(2), c=8.364(2) A, Z=6, V=785.0(2) A 3 ) and BaLi 1.12 In 0.98 : P6/mmm, a=17.469(1), c=10.6409(7) A, Z=30, V=2813.5(8) A 3 ), while BaLi 1.06 In 1.16 has a rhombohedral structure (R-3c, a=18.894(3), c=85.289(17) A, Z=276, V=26368(8) A 3 ). BaLi 2.1 In 1.9 is isostructural with the known phase BaLi 4 . The phase BaLi 1.12 In 0.98 is structurally related to Na 8 K 23 Cd 12 In 48 , while BaLi 1.06 In 1.16 is isostructural with Li 33.3 Ba 13.1 Ca 3 . A sample containing structurally similar BaLi 1.12 In 0.98 and BaLi 1.02 In 1.16 was also investigated by transmission electron microscopy. Li 35 In 45 Ba 39 N 9 and LiIn 2 Ba 3 N 0.83 crystallize with tetragonal (I-42m, a=15.299(2), c=30.682(6) A, Z=2, V=7182(2) A 3 ) and cubic (Fd-3m, a=14.913(2) A, Z=8, V=3316.7(7) A 3 ) symmetry, respectively. While the first-mentioned subnitride belongs to the Li 80 Ba 39 N 9 structure type, the second extends the structural family of Ba 6 In 4.78 N 2.72 . The structural features of the new compounds are discussed in comparison to the known phases and the results of total energy calculations. - Graphical abstract: One-dimensional chain of face-sharing centered icosahedra in BaLi 2.1 In 1.9

  9. Wet routes of high purity BaTiO3 nanopowders

    International Nuclear Information System (INIS)

    Wang Liqiu; Liu Liang; Xue Dongfeng; Kang Hongmin; Liu Changhou

    2007-01-01

    High purity BaTiO 3 nanopowders were prepared in wet routes through stearic acid gel (SAG) and acetic acid gel (AAG) techniques, respectively. BaTiO 3 samples were characterized by X-ray diffraction, transmission electron microscope, Fourier transform infrared spectrometry, X-ray fluorescence spectrometry, and thermal gravimetric analysis. The present results indicate that both methods have a similar reaction process during calcination, while BaTiO 3 crystallites were initially formed at 550 deg. C by SAG and 800 deg. C by AAG. Both methods could produce BaTiO 3 powders with a cubic perovskite structure, while they had different grain size distributions within 25-50 nm for SAG and 50-80 nm for AAG. BaTiO 3 samples prepared by SAG had a lower agglomeration than those by AAG. SAG has shown many distinctive advantages in the preparation of high purity BaTiO 3 nanopowders, without Ba and Ti losses and hazardous wastes

  10. Ferroelectric relaxor Ba(TiCe)O3

    International Nuclear Information System (INIS)

    Chen Ang; Zhi Jing; Yu Zhi

    2002-01-01

    The dielectric behaviour of Ba(Ti 1-y Ce y )O 3 solid solutions (y=0-0.3) has been studied. A small amount of Ce doping (y=0.02) has weak influence on the dielectric behaviour of Ba(Ti 1-y Ce y )O 3 . With increasing Ce concentration, three phase transitions of pure BaTiO 3 are pinched into one rounded dielectric peak with frequency dispersion, and the relaxation time follows the Vogel-Fulcher relation. The evolution from a normal ferroelectric to a ferroelectric relaxor is emphasized. High strains (S=∼0.1-0.19%) with a small hysteresis under ac fields are obtained in ferroelectric relaxors Ba(Ti 1-y Ce y )O 3 . The physical mechanism of the relaxation process, the pinching effect of the phase transitions and their influence on the ferroelectric and electrostrictive behaviour are discussed. (author)

  11. Stingless bees further improve apple pollination and production

    Directory of Open Access Journals (Sweden)

    Blandina Felipe Viana

    2014-10-01

    Full Text Available The use of Africanised honeybee (Apis mellifera scutellata Lepeletier hives to increase pollination success in apple orchards is a widespread practice. However, this study is the first to investigate the number of honeybee hives ha-1 required to increase the production of fruits and seeds as well as the potential contribution of the stingless bee Mandaçaia (Melipona quadrifasciata anthidioides Lepeletier. We performed tests in a 43-ha apple orchard located in the municipality of Ibicoara (13º24’50.7’’S and 41º17’7.4’’W in Chapada Diamantina, State of Bahia, Brazil. In 2011, fruits from the Eva variety set six seeds on average, and neither a greater number of hives (from 7 to 11 hives ha-1 nor a greater number of pollen collectors at the honeybee hives displayed general effects on the seed number. Without wild pollinators, seven Africanised honeybee hives ha-1 with pollen collectors is currently the best option for apple producers because no further increase in the seed number was observed with higher hive densities. In 2012, supplementation with both stingless bees (12 hives ha-1 and Africanised honeybees (7 hives ha-1 provided higher seed and fruit production than supplementation with honeybees (7 hives ha-1 alone. Therefore, the stingless bee can improve the performance of honeybee as a pollinator of apple flowers, since the presence of both of these bees results in increases in apple fruit and seed number.

  12. Microbial Community Profile and Water Quality in a Protected Area of the Caatinga Biome.

    Science.gov (United States)

    Lopes, Fabyano Alvares Cardoso; Catão, Elisa Caldeira Pires; Santana, Renata Henrique; Cabral, Anderson de Souza; Paranhos, Rodolfo; Rangel, Thiago Pessanha; de Rezende, Carlos Eduardo; Edwards, Robert A; Thompson, Cristiane C; Thompson, Fabiano L; Kruger, Ricardo Henrique

    2016-01-01

    The Caatinga is a semi-arid biome in northeast Brazil. The Paraguaçú River is located in the Caatinga biome, and part of its course is protected by the National Park of Chapada Diamantina (PNCD). In this study we evaluated the effect of PNCD protection on the water quality and microbial community diversity of this river by analyzing water samples obtained from points located inside and outside the PNCD in both wet and dry seasons. Results of water quality analysis showed higher levels of silicate, ammonia, particulate organic carbon, and nitrite in samples from the unprotected area compared with those from protected areas. Pyrosequencing of the 16S rRNA genes revealed that Burkholderiales was abundant in samples from all three sites during both seasons and was represented primarily by the genus Polynucleobacter and members of the Comamonadaceae family (e.g., genus Limnohabitans). During the dry season, the unprotected area showed a higher abundance of Flavobacterium sp. and Arthrobacter sp., which are frequently associated with the presence and/or degradation of arsenic and pesticide compounds. In addition, genes that appear to be related to agricultural impacts on the environment, as well as those involved in arsenic and cadmium resistance, copper homeostasis, and propanediol utilization, were detected in the unprotected areas by metagenomic sequencing. Although PNCD protection improves water quality, agricultural activities around the park may affect water quality within the park and may account for the presence of bacteria capable of pesticide degradation and assimilation, evidencing possible anthropogenic impacts on the Caatinga.

  13. Metaplasia mieloide do baço na Ancilostomose

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    W. O. Cruz

    1934-06-01

    Full Text Available Pesquizamos, no figado e baço de dez casos puros de ancilostomose, elementos hemocitopoieticos; verificamos o peso do baço em 23 casos de individuos com idades compreendidas entre 3 e 60 anos; não encontramos, em nenhum caso, celulas hemoformadoras no figado. Em sete casos, encontramos, no baço, elementos da série vermelha em adiantado estado de evolução (eritroblastos ortocromaticos de nucleo picnotico. Em alguns destes casos observamos megacariocitos e numerosos mielocitos eosinofilos. Os tres casos que não apresentavam metaplasia mieloide no baço, eram os de individuos acima de 50 anos de idade. Entretanto, em outro caso de um individuo com 59 anos esta metaplasia foi verificada. Em individuos acima de 20 anos, o peso médio do baço, em nove casos, mostrou-se igual ao peso normal. Em 14 casos, compreendidos entre 3 e 14 anos, o peso deste orgão foi sempre sensivelmente mais elevado que nos normais de idade correspondente. Estes resultados sugerem a possibilidade de ser a metaplasia mieloide responsavel pelos aumentos de pezo nos baços de individuos jovens, vitimados pela anemia ancilostomica. A notavel proliferação dos eritroblastos ortocromaticos mostra que o grão e a rapidez da regeneração sanguinea, após a administração de ferro, são devidos, essencialmente, á grande quantidade de hemoglobina já preformada no baço e na medula ossea dos organismos ancilostomados.

  14. Compounds of the type Ba/sub 3/Bsup(II)M/sub 2/sup(V)O/sub 9/ with Bsup(II) = Mg, Ca, Sr, Ba, and Msup(V) = Nb, Ta

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Thumm, I; Herrmann, M [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1981-08-01

    The hexagonal perovskites Ba/sub 3/Bsup(II)M/sub 2/sup(V)O/sub 9/ (Msup(V) = Nb, Ta) crystallize with Bsup(II) = Mg, Ca in a 3 L structure (sequence (c)/sub 3/) and Bsup(II) = Sr in the hexagonal BaTiO/sub 3/ type (6 L; sequence (hcc)/sub 2/) with an 1:2 order for the B and M ions. Intensity calculations for Ba/sub 3/SrNb/sub 2/O/sub 9/ and Ba/sub 3/SrTa/sub 2/O/sub 9/ gave in the space group P6/sub 3//mmc a refined, intensity related R' value of 8.4% (Nb) and 9.0% (Ta) respectively. For Bsup(II) = Ba the perovskite Ba/sub 3/BaTa/sub 2/O/sub 9/ has an orthorhombic distorted 6 L structure and forms with Ba/sub 3/SrTa/sub 2/O/sub 9/ a continuous series of mixed crystals (Ba/sub 3/Srsub(1-x)Basub(x)Ta/sub 2/O/sub 9/). In the system Ba/sub 3/Srsub(1-x)Basub(x)Nb/sub 2/O/sub 9/ the range of existence of the hexagonal BaTiO/sub 3/ type is confined to the Sr richer end. The pure Ba compound posesses a proper structure type (5 L: Ba/sub 5/BaNb/sub 3/vacantOsub(13.5)vacantsub(1.5)).

  15. First-principles study of (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 solid solutions

    Science.gov (United States)

    Amoroso, Danila; Cano, Andrés; Ghosez, Philippe

    2018-05-01

    (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 solid solutions are the building blocks of lead-free piezoelectric materials that attract a renewed interest. We investigate the properties of these systems by means of first-principles calculations, with a focus on the lattice dynamics and the competition between different ferroelectric phases. We first analyze the four parent compounds in order to compare their properties and their different tendency towards ferroelectricity. The core of our study is systematic characterization of the binary systems (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 within both the virtual crystal approximation and direct supercell calculations. In the case of Ca doping, we find a gradual transformation from B -site to A -site ferroelectricity due to steric effects that largely determines the behavior of the system. In the case of Zr doping, in contrast, the behavior is eventually dominated by cooperative Zr-Ti motions and the local electrostatics. In addition, our comparative study reveals that the specific microscopic physics of these solids sets severe limits to the applicability of the virtual crystal approximation for these systems.

  16. Electronic structure of Ca, Sr, and Ba under pressure.

    Science.gov (United States)

    Animalu, A. O. E.; Heine, V.; Vasvari, B.

    1967-01-01

    Electronic band structure calculations phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure

  17. Effect of Barium-Precursors on Reaction Kinetics in Y-Ba-Cu-O System

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The reactions of stoichiometric Y2O3, CuO, and different Ba salts or oxides (BaCO3, Ba(NO3)2, BaO2, BaCuO2) for forming various compounds in the Y-Ba-Cu-O system (i.e., YBa2Cu3O7-δ, BaCuO2, Y2BaCuO5 and Y2Cu2O5) were systematically investigated by thermal analysis and X-ray diffractometry. The relevant activation energies were calculated from thermogravimetric data. It is found that the reaction pathway significantly depends on the thermal stability of the Ba precursors. Binary BaO-CuO phases form at low temperature (650~700 ℃) when in presence of easy-to-decompose Ba precursors, and then slowly transform to ternary compounds. On the contrary, when Ba ions are released at temperature higher than 900 ℃, ternary phases form directly from the components.

  18. Strain induced optical properties of BaReO3

    Science.gov (United States)

    Kumavat, Sandip R.; Kansara, Shivam; Gupta, Sanjeev K.; Sonvane, Yogesh

    2018-05-01

    Here, we have performed strain induce optical properties of BaReO3 by using density functional theory (DFT). We noticed that after applying intrinsic and extrinsic strain to the BaReO3, it shows the metallic behavior. We also studied optical properties, which show good activity in the ultraviolet region. The results show that after applying intrinsic and extrinsic strain to BaReO3 the absorption peaks are shifted towards the high UV region of the spectrum. Thus, we concluded that, BaReO3 material with extrinsic strain can be useful for high frequency UV device and optoelectronic devices.

  19. IR-spectroscopic study and electrical properties of glasses in the Ba(PO3)2-Ba(Hal)2 systems

    International Nuclear Information System (INIS)

    Sokolov, I.A.; Tarlakov, Yu.P.; Murin, I.V.; Pronkin, A.A.

    2000-01-01

    Temperature-concentration dependence of electric conductivity of glasses in the systems Ba(PO 3 ) 2 -Ba(Hal) 2 , where Hal = Cl, Br, I, is studied by the method of conductometry, the numbers of iodide-ions transfer are determined and their concentration dependence is found. Data of IR spectroscopy permitted ascertained participation of halide ions in formation of anionic constituent of the glass structure at the expense of bridge bonds formation, as well as formation of structural-chemical units of [(Hal) - Ba 2+ O - POO 2/2 ] type, their dissociation giving rise to formation of halide ions their dissociation giving rise to formation of halide ions taking part in electric current transfer [ru

  20. High-Temperature Superconductivity in Doped BaFe2As2

    International Nuclear Information System (INIS)

    Martin, Marianne

    2011-01-01

    This thesis provides a detailed look on the synthesis, structural features and physical properties of iron arsenides. Especially the properties of BaFe 2 As 2 and the solid solutions (Ba 1-x K x )Fe 2 As 2 , (Ba 1-x Sr x )Fe 2 As 2 and BaFe 2 (As 1-x P x ) 2 which were all synthesized by solid state reactions by heating mixtures of the elements, were intensively investigated.

  1. Molecular recognition at methyl methacrylate/n-butyl acrylate (MMA/nBA) monomer unit boundaries of phospholipids at p-MMA/nBA copolymer surfaces.

    Science.gov (United States)

    Yu, Min; Urban, Marek W; Sheng, Yinghong; Leszczynski, Jerzy

    2008-09-16

    Lipid structural features and their interactions with proteins provide a useful vehicle for further advances in membrane proteins research. To mimic one of potential lipid-protein interactions we synthesized poly(methyl methacrylate/ n-butyl acrylate) (p-MMA/nBA) colloidal particles that were stabilized by phospholipid (PLs). Upon the particle coalescence, PL stratification resulted in the formation of surface localized ionic clusters (SLICs). These entities are capable of recognizing MMA/nBA monomer interfaces along the p-MMA/nBA copolymer backbone and form crystalline SLICs at the monomer interface. By utilizing attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy and selected area electron diffraction (SAD) combined with ab initio calculations, studies were conducted that identified the origin of SLICs as well as their structural features formed on the surface of p-MMA/nBA copolymer films stabilized by 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) PL. Specific entities responsible for SLIC formation are selective noncovalent bonds of anionic phosphate and cationic quaternary ammonium segments of DLPC that interact with two neighboring carbonyl groups of nBA and MMA monomers of the p-MMA/nBA polymer backbone. To the best of our knowledge this is the first example of molecular recognition facilitated by coalescence of copolymer colloidal particles and the ability of PLs to form SLICs at the boundaries of the neighboring MMA and nBA monomer units of the p-MMA/nBA chain. The dominating noncovalent bonds responsible for the molecular recognition is a combination of H-bonding and electrostatic interactions.

  2. Epitaxial thin-film growth of Ruddlesden-Popper-type Ba3Zr2O7 from a BaZrO3 target by pulsed laser deposition

    International Nuclear Information System (INIS)

    Butt, Shariqa Hassan; Rafique, M.S.; Siraj, K.; Latif, A.; Afzal, Amina; Awan, M.S.; Bashir, Shazia; Iqbal, Nida

    2016-01-01

    Ruddlesden-Popper Ba 3 Zr 2 O 7 thin films have been synthesized via pulsed laser deposition (PLD) technique. The optimization of deposition parameters in PLD enables the formation of thin film of metastable Ba 3 Zr 2 O 7 phase from BaZrO 3 target. In order to see the post-annealing effects on the structural and optical properties, the deposited Ba 3 Zr 2 O 7 thin films were annealed at 500, 600 and 800 C. X-ray diffraction (XRD) reveals the formation of Ba 3 Zr 2 O 7 phase with tetragonal structure. The changes in the surface of the deposited films were analysed by FE-SEM and AFM. The thin film post-annealed at 500 C exhibited the best structural, optical and surface properties. Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. The XPS results show that Ba, Zr and O exist mainly in the form of Ba 3 Zr 2 O 7 Ruddlesden-Popper-type perovskite structure. (orig.)

  3. Experimental study on Ra2+ uptake by barite (BaSO{sub 4}). Kinetics of solid solution formation via BaSO{sub 4} dissolution and Ra{sub x}Ba{sub 1-x}SO{sub 4} (re) precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Bosbach, Dirk; Boettle, Melanie; Metz, Volker (Karlsruher Inst. fuer Technologie, Inst fuer Nukleare Entsorgung (INE), Karlsruhe (Germany))

    2010-03-15

    226Ra2+ and 133Ba2+ uptake by barite in aqueous solution is studied on the basis of batch type experiments with two different barite powders with different specific surface area (0.5 m2/g and 3.2 m2/g, respectively). The uptake of 226Ra2+ and 133Ba2+ is not only limited to adsorption reactions but proceeds significantly into the bulk of the barite crystals. 133Ba2+ uptake kinetics is affected by various parameters, such as amount of sample, specific surface area, sample type and solution composition. In the case of 133Ba2+, complete isotopic equilibration of the 133Ba2+ spiked solution with the barite powder occurs within 50 to 600 days. This information is derived by monitoring the aqueous 133Ba2+ concentration combined with simple mass balance calculations. In the case of 226Ra2+ a Ra{sub x}Ba{sub 1-x}SO{sub 4} solid solution forms and the uptake rate drops significantly within 400 days. The observed 226Ra2+ concentration in solution is controlled by the solubility of a Ra{sub x}Ba{sub 1-x}SO{sub 4} solid solution and several orders of magnitude below the Ra2+ solubility with respect to a pure RaSO{sub 4}(s) end member. It cannot be demonstrated unambiguously that a zero exchange rate and therefore thermodynamic equilibrium has been established within the observation period. The observed concentrations may be interpreted either as (1) a partial equilibration of 20 to 50% of the barite crystals with 226Ra2+ or (2) as complete equilibration of a Ra{sub 0.000128}Ba{sub 0.999872}SO{sub 4} solid solution with 226Ra2+ with no pure barite left. In both cases it is concluded that equilibration between aqueous Ra2+ and barite involves the replacement of a substantial fraction of the initial barite and proceeds significantly beyond pure surface adsorption processes

  4. Enhancement of polarization property of silane-modified BaTiO3 nanoparticles and its effect in increasing dielectric property of epoxy/BaTiO3 nanocomposites

    Directory of Open Access Journals (Sweden)

    Thi Tuyet Mai Phan

    2016-03-01

    Full Text Available The surface modification of synthesized nano-BaTiO3 particles was carried out using γ-aminopropyl trimethoxy silane (γ-APS in an ethanol/water solution. The modified particles were characterized by FTIR, TGA, surface charge analysis, and by dielectric constant measurement. The silane molecules were attached to the surface of BaTiO3 particles through SiOBaTiO3 bonds. The γ-APS grafted on BaTiO3 made the dielectric constant of the particles increase at frequencies ≥0.3 kHz in a wide range of temperature (25 °C–140 °C, due to the presence of NH2 groups. The dependence of the polarization vs. electrical field was measured in order to elucidate the dielectric behavior of the silane treated BaTiO3 in comparison to untreated BaTiO3. The nanocomposite based on epoxy resin containing BaTiO3 nanoparticles untreated and treated with γ-APS was also prepared and characterized. The results indicated that the γ-APS-modified BaTiO3 surfaces significantly enhanced the dielectric property of the nanocomposite.

  5. Controlled Confinement of Half-metallic 2D Electron Gas in BaTiO3/Ba2FeReO6/BaTiO3 Heterostructures: A First-principles Study

    Science.gov (United States)

    Saha-Dasgupta, Tanusri; Baidya, Santu; Waghmare, Umesh; Paramekanti, Arun

    Using density functional theory calculations, we establish that the half-metallicity of bulk Ba2FeReO6 survives down i to 1 nm thickness in BaTiO3/Ba2FeReO6/BaTiO3 heterostructures grown along the (001) and (111) directions. The confinement of the two-dimensional (2D) electron gas in this quantum well structure arises from the suppressed hybridization between Re/Fe d states and unoccupied Ti d states, and it is further strengthened by polar fields for the (111) direction. This mechanism, distinct from the polar catastrophe, leads to an order of magnitude stronger confinement of the 2D electron gas than that at the LaAlO3/SrTiO3 interface. We further show low-energy bands of (111) heterostructure display nontrivial topological character. Our work opens up the possibility of realizing ultra-thin spintronic devices. Journal Ref: Phys. Rev. B 92, 161106(R) (2015) S.B. and T.S.D thank Department of Science and Technology, India for the support through Thematic Unit of Excellence. AP was supported by NSERC (Canada).

  6. The new barium zinc mercurides Ba3ZnHg10 and BaZn0.6Hg3.4 – Synthesis, crystal and electronic structure

    International Nuclear Information System (INIS)

    Schwarz, Michael; Wendorff, Marco; Röhr, Caroline

    2012-01-01

    The title compounds Ba 3 ZnHg 10 and BaZn 0.6 Hg 3.4 were synthesized from stoichiometric ratios of the elements in Ta crucibles. Their crystal structures, which both represent new structure types, have been determined using single crystal X-ray data. The structure of Ba 3 ZnHg 10 (orthorhombic, oP28, space group Pmmn, a=701.2(3), b=1706.9(8), c=627.3(3)pm, Z=2, R1=0.0657) contains folded 4 4 Hg nets, where the meshes form the bases of flat rectangular pyramids resembling the structure of BaAl 4 . The flat pyramids are connected via Hg–Zn/Hg bonds, leaving large channels at the folds, in which Ba(1) and Hg(2) atoms alternate. Whereas the remaining Hg/Zn atoms form a covalent 3D network of three- to five-bonded atoms with short M–M distances (273–301 pm; CN 9–11), the Hg(2) atoms in the channels adopt a comparatively large coordination number of 12 and increased distances (317–348 pm) to their Zn/Hg neighbours. In the structure of BaZn 0.6 Hg 3.4 (cubic, cI320, space group I4 ¯ 3d, a=2025.50(7) pm, Z=64, R1=0.0440), with a chemical composition not much different from that of Ba 3 ZnHg 10 , the Zn/Hg atoms of the mixed positions M(1/2) are arranged in an slightly distorted primitive cubic lattice with a 4×4×4 subcell relation to the unit cell. The 24 of the originating 64 cubes contain planar cis tetramers Hg(5,6) 4 with Hg in a nearly trigonal planar or tetrahedral coordination. In another 24 of the small cubes, two opposing faces are decorated by Hg(3,4) 2 dumbbells, two by Ba(2) atoms respectively. The third type of small cubes are centered by Ba(1) atoms only. The complex 3D polyanionic Hg/Zn network thus formed is compared with the Hg partial structure in Rb 3 Hg 20 applying a group-subgroup relation. Despite their different overall structures, the connectivity of the negatively charged Hg atoms, the rather metallic Zn bonding characteristic (as obtained from FP-LAPW band structure calculations) and the coordination number of 16 for all Ba cations

  7. Gametogenesis and reproductive cycle of Melanorivulus aff. punctatus (Boulenger, 1895 (Cyprinodontiformes, Rivulidae in Chapada dos Guimarães, Mato Grosso, Brazil

    Directory of Open Access Journals (Sweden)

    Monica Cassel

    Full Text Available The comprehension of the reproductive cycle allows to understand which are the morphological changes that develop in the gonad during this interval. Thus, many studies have been undertaken in order to describe and classify the stages of gonadal development and reproductive status of Neotropical fishes. For this purpose, specimens of Melanorivulus aff. punctatus were collected in a permanent dam in Chapada dos Guimarães, Mato Grosso, Brazil. The gonads were prepared for analysis by light microscopy. The oogenesis and spermatogenesis have been described, characterizing the stages of gonadal development, together with assessments of the gonadosomatic ratio, germ cell count and verification of variation of mature oocytes in females. Throughout the year the male gonads presented themselves as capable of reproducing, characterized by the presence of undifferentiated and differentiated spermatogonia, spermatocytes organized into cysts, spermatids in cysts whose wall was thicker and the spermatozoa was free in the lumen and the duct. This can indicate a continuous reproductive cycle with split spermiation. The females had gonads in the development stage from May to September with undifferentiated and differentiated oogonias and early oocytes always facing the lumen, abundant pre-vitellogenic and vitellogenic oocytes and some atresias. In the phase capable of spawning, observed from October to March, the mature oocytes are abundant, there are many post-ovulatory complexes and some atresia in advanced stage. The regression, observed in some individuals from February to April, is characterized by ovaries with many atresias and post-ovulatory complexes. The same results were found in the quantitative assessments. Therefore, it may be characterized as discontinuous cycle with split spawning. Thus, the reproductive cycle of this species can be characterized as continuous for males and discontinuous for females, which have a most intense phase of reproduction

  8. Dynamics of photoexcited Ba{sup +} cations in {sup 4}He nanodroplets

    Energy Technology Data Exchange (ETDEWEB)

    Leal, Antonio; Pi, Martí [Departament ECM, Facultat de Física, and IN" 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Zhang, Xiaohang; Drabbels, Marcel [Laboratoire de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Barranco, Manuel [Departament ECM, Facultat de Física, and IN" 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France); Cargnoni, Fausto [Istituto di Scienze e Tecnologie Molecolari (ISTM), Consiglio Nazionale delle Ricerche, via Golgi 19, 20133 Milano (Italy); Hernando, Alberto [Social Thermodynamics Applied Research (SThAR), EPFL Innovation Park, Bâtiment C, CH-1015 Lausanne (Switzerland); Mateo, David [Department of Chemistry and Biochemistry, California State University at Northridge, Northridge, California 91330 (United States); Mella, Massimo [Dipartimento di Scienza ed Alta Tecnologia, Università degli Studi dell’Insubria, via Valleggio 11, 22100 Como (Italy)

    2016-03-07

    We present a joint experimental and theoretical study on the desolvation of Ba{sup +} cations in {sup 4}He nanodroplets excited via the 6p ← 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba{sup +} cations and Ba{sup +}He{sub n} exciplexes with n = 1 and 2. The speed distributions of the ions are well described by Maxwell-Boltzmann distributions with temperatures ranging from 60 to 178 K depending on the excitation frequency and Ba{sup +} He{sub n} exciplex size. These results have been analyzed by calculations based on a time-dependent density functional description for the helium droplet combined with classical dynamics for the Ba{sup +}. In agreement with experiment, the calculations reveal the dynamical formation of exciplexes following excitation of the Ba{sup +} cation. In contrast to experimental observation, the calculations do not reveal desolvation of excited Ba{sup +} cations or exciplexes, even when relaxation pathways to lower lying states are included.

  9. Thermoelectric properties of doped BaHfO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Dixit, Chandra Kr., E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com [Dept. of Physics, Dr. Shakuntala Misra National Rehabilitation University, Lucknow-229001, U.P India (India); Bhamu, K. C. [Department of Physics, Goa University, Goa-403 206 (India); Sharma, Ramesh, E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com [Dept. of Physics, Feroze Gandhi Institute of Engineering & Technology, Raebareli-229001, U.P India (India)

    2016-05-06

    We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO{sub 3} by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO{sub 3} doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. The doped BaHfO{sub 3} is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO{sub 3} is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.

  10. Operability test procedure for 211BA flow proportional sampler

    International Nuclear Information System (INIS)

    Weissenfels, R.D.

    1994-01-01

    The purpose of this operability test procedure (OTP) is to verify the 211-BA flow proportional sampler system and components function correctly as intended by design. System test will include the sampling system, all associated instrumentation, and Facility Process Monitor and Control System (FPMCS). The combined chemical sewer stream from B Plant flows through sump 211BA-SMP-01 located in 211-BA and is continuously monitored for gamma and beta radiation and pH. 211-BA has been upgraded to include a flow proportional sampler. A specified sample volume will be withdrawn at programmed intervals from the 211BA sump and deposited in a 19 liter plastic carboy. The sampler will be programmed per the vendor installation and operations manual by B Plant instrument maintenance personnel. Samples will be taken during five consecutive sample cycles with the sample volumes and sample frequencies recorded for comparison purposes. Additional tests related to the sampler include the alarm circuitry for loss of power and failure to obtain sample

  11. Ba-bah on tulnud / Liina Jänes

    Index Scriptorium Estoniae

    Jänes, Liina, 1977-

    2005-01-01

    Eesti noori disainereid-sisearhitekte ühendavast disainiagentuurist Ba-bah, selle eesmärgist. Agentuuri juhib Veiko Jääger. Mais 2005 Disaini- ja Arhitektuurigaleriis toimunud Ba-bahi avanäitusest, kus oli väljas töid EKA sisearhitektuuri, klaasi-, ehte- ja sepakunsti eriala üliõpilastelt ning metallmööbli valmistajalt Kalle Pruudenilt

  12. The microscopic twins and their crystal phase in the high Tc Y-Ba-Cu-O and Dy-Ba-Cu-O superconductive ceramics

    International Nuclear Information System (INIS)

    Zu, Z.J.; Chen, Y.L.

    1988-01-01

    Most consider that the structure of Y-Ba- Cu-O and Dy-Ba-Cu-O stable superconductive crystals with high Tc is associated with the right-angled phase. The superconductivity is closely connected with the right-angled character of the crystalline texture; the better the right- angled character, the better the superconductivity. From statistical investigations of examples the authors have discovered that most of the Y-Ba-Cu-O and Dy-Ba-Cu-O superconductivity with high Tc ceramic crystals is in the monoclinic phase, which, consists of microscopic, lamellar, single twins. The long-columnar grains consisting of lamellar twin slabs show the optical characteristics of right-angled phase. The microscopic twinning and grain morphologies are summarized in this paper

  13. Local manifestations of a static magnetoelectric effect in nanostructured BaTiO3-BaFe12O9 composite multiferroics

    Science.gov (United States)

    Trivedi, Harsh; Shvartsman, Vladimir V.; Lupascu, Doru C.; Medeiros, Marco S. A.; Pullar, Robert C.; Kholkin, Andrei L.; Zelenovskiy, Pavel; Sosnovskikh, Andrey; Shur, Vladimir Ya.

    2015-02-01

    A study on magnetoelectric phenomena in the barium titanate-barium hexaferrite (BaTiO3-BaFe12O19) composite system, using high resolution techniques including switching spectroscopy piezoresponse force microscopy (SSPFM) and spatially resolved confocal Raman microscopy (CRM), is presented. It is found that both the local piezoelectric coefficient and polarization switching parameters change on the application of an external magnetic field. The latter effect is rationalized by the influence of magnetostrictive stress on the domain dynamics. Processing of the Raman spectral data using principal component analysis (PCA) and self-modelling curve resolution (SMCR) allowed us to achieve high resolution phase distribution maps along with separation of average and localized spectral components. A significant effect of the magnetic field on the Raman spectra of the BaTiO3 phase has been revealed. The observed changes are comparable with the classical pressure dependent studies on BaTiO3, confirming the strain mediated character of the magnetoelectric coupling in the studied composites.

  14. The BaBar silicon vertex tracker

    International Nuclear Information System (INIS)

    Bozzi, C.; Carassiti, V.; Ramusino, A. Cotta; Dittongo, S.; Folegani, M.; Piemontese, L.; Abbott, B.K.; Breon, A.B.; Clark, A.R.; Dow, S.; Fan, Q.; Goozen, F.; Hernikl, C.; Karcher, A.; Kerth, L.T.; Kipnis, I.; Kluth, S.; Lynch, G.; Levi, M.; Luft, P.; Luo, L.; Nyman, M.; Pedrali-Noy, M.; Roe, N.A.; Zizka, G.; Roberts, D.; Barni, D.; Brenna, E.; Defendi, I.; Forti, A.; Giugni, D.; Lanni, F.; Palombo, F.; Vaniev, V.; Leona, A.; Mandelli, E.; Manfredi, P.F.; Perazzo, A.; Re, V.; Angelini, C.; Batignani, G.; Bettarini, S.; Bondioli, M.; Bosi, F.; Calderini, G.; Carpinelli, M.; Dutra, F.; Forti, F.; Gagliardi, D.; Giorgi, M.A.; Lusiani, A.; Mammini, P.; Morganti, M.; Morsani, F.; Paoloni, E.; Profeti, A.; Rama, M.; Rampino, G.; Rizzo, G.; Sandrelli, F.; Simi, G.; Triggiani, G.; Tritto, S.; Vitale, R.; Burchat, P.; Cheng, C.; Kirkby, D.; Meyer, T.; Roat, C.; Bona, M.; Bianchi, F.; Daudo, F.; Girolamo, B. Di; Gamba, D.; Giraudo, G.; Grosso, P.; Romero, A.; Smol, A.; Trapani, P.; Zanin, D.; Bosisio, L.; Ricca, G. Della; Lanceri, L.; Pompili, A.; Poropat, P.; Prest, M.; Rastelli, C.; Vallazza, E.; Vuagnin, G.; Hast, C.; Potter, E.P.; Sharma, V.; Burke, S.; Callahan, D.; Campagnari, C.; Dahmes, B.; Eppich, A.; Hale, D.; Hall, K.; Hart, P.; Kuznetsova, N.; Kyre, S.; Levy, S.; Long, O.; May, J.; Richman, J.; Verkerke, W.; Witherell, M.; Beringer, J.; Eisner, A.M.; Frey, A.; Grillo, A.; Grothe, M.; Johnson, R.; Kroeger, W.; Lockman, W.; Pulliam, T.; Rowe, W.; Schmitz, R.; Seiden, A.; Spencer, E.; Turri, M.; Wilder, M.; Charles, E.; Elmer, P.; Nielsen, J.; Orejudos, W.; Scott, I.; Walsh, J.; Zobernig, H.

    2000-01-01

    The BaBar Silicon Vertex Tracker (SVT) is designed to provide the high-precision vertexing necessary for making measurements of CP violation at the SLAC B-Factory PEP-II. The instrument consists of five layers of double-sided silicon strip detectors and has been installed in the BaBar experiment and taking colliding beam data since May 1999. An overview of the design as well as performance and experience from the initial running will be presented

  15. Genome Sequence of African Swine Fever Virus BA71, the Virulent Parental Strain of the Nonpathogenic and Tissue-Culture Adapted BA71V.

    Science.gov (United States)

    Rodríguez, Javier M; Moreno, Leticia Tais; Alejo, Alí; Lacasta, Anna; Rodríguez, Fernando; Salas, María L

    2015-01-01

    The strain BA71V has played a key role in African swine fever virus (ASFV) research. It was the first genome sequenced, and remains the only genome completely determined. A large part of the studies on the function of ASFV genes, viral transcription, replication, DNA repair and morphogenesis, has been performed using this model. This avirulent strain was obtained by adaptation to grow in Vero cells of the highly virulent BA71 strain. We report here the analysis of the genome sequence of BA71 in comparison with that of BA71V. They possess the smallest genomes for a virulent or an attenuated ASFV, and are essentially identical except for a relatively small number of changes. We discuss the possible contribution of these changes to virulence. Analysis of the BA71 sequence allowed us to identify new similarities among ASFV proteins, and with database proteins including two ASFV proteins that could function as a two-component signaling network.

  16. Praseodymium valency from crystal structure in Pr-Ba-Cu-O and (Y-Pr)-Ba-Cu-O single crystals

    International Nuclear Information System (INIS)

    Collin, G.; Albouy, P.A.; Monod, P.; Ribault, M.

    1990-01-01

    The substitution of Pr to Y leads to materials with a general formula (Y 1-v Pr v ) (Ba 2-x Pr x ) (Cu 3-y vac y ) O 6+x/2-y+z and with a structural transition around v + x' ∼ 0.5. For v + x 0.5 the crystals are tetragonal, La 1.5 Ba 1.5 Cu 3 O 7±z type, with the characteristic tri-twinning of this phase. The Pr valency, in the range 3-3.2 + depending on preparation conditions, is determined from interatomic distances. Orthorhombic crystals of Pr Ba Cu O prepared at high temperatures exhibit a high amount of defects, y ∼ 0.25 on the Cu(1) site and are semiconductors with a T -1/4 activation law attributed to the praseodymium valence fluctuation

  17. Histological evidence of reproductive activity in lizards from the APM Manso, Chapada dos Guimarães, Mato Grosso State, Brazil - doi: 10.4025/actascibiolsci.v34i3.9228

    Directory of Open Access Journals (Sweden)

    Adelina Ferreira

    2012-06-01

    Full Text Available The construction of dams causes major impacts on fauna by changing or eliminating irreversibly their habitats. The resulting changes lead to deep potential modifications on reproductive biology and population structure of lizards, snakes and amphisbaenas. The reservoir in the Multiple Use Area of Manso (APM-Manso is located near to Chapada dos Guimarães National Park, in Mato Grosso State. We analyzed comparatively the male gonads of Anolis meridionalis, Colobosaura modesta, Cercosaura ocellata, Cnemidophorus ocellifer, Hoplocercus spinosus, Bachia bresslaui, Mabuya frenata, Micrablepharus atticolus and Tropidurus oreadicus, from APM-Manso, aiming to verify possible changes in the reproductive success according to environmental changes. Before the impoundment  A. meridionalis, Colobosaura modesta, Cercosaura ocellata, M. atticolus and T. oreadicus showed up reproductive. However, during the impoundment period they presented changes in seminiferous tubules, evidenced by the absence of spermatids and spermatozoids. B. bresslaui and M. frenata had no differences in the seminiferous tubules before and after the impoundment, being reproductive in both moments. The damming and the formation of the lake of Manso reservoir may have interfered on the reproduction of some lizards species, especially if the reproductive cycle is regulated by the rainfall of the habitat. 

  18. Structural evolution of Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} from BaTiO{sub 3} using a series of Ba(Ti{sub 1−5x}Nb{sub 4x})O{sub 3} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Barrientos Hernández, F.R., E-mail: frbh68@hotmail.com [Academic Area of Earth Sciences and Materials, Autonomous University of Hidalgo State, Road Pachuca-Tulancingo km 4.5, Mineral de la Reforma zip code 42184, Hidalgo (Mexico); Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Lira Hernández, I.A. [Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Industrial Engineering Department, Technological Institute of Pachuca, Road México-Pachuca km. 87.5, Pachuca de Soto zip code 42080, Hidalgo (Mexico); Gómez Yáñez, C. [Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Arenas Flores, A. [Academic Area of Earth Sciences and Materials, Autonomous University of Hidalgo State, Road Pachuca-Tulancingo km 4.5, Mineral de la Reforma zip code 42184, Hidalgo (Mexico); Cabrera Sierra, R. [Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Pérez Labra, M. [Academic Area of Earth Sciences and Materials, Autonomous University of Hidalgo State, Road Pachuca-Tulancingo km 4.5, Mineral de la Reforma zip code 42184, Hidalgo (Mexico)

    2014-01-15

    Highlights: • The evolution phase Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} was obtained through the mechanism Ba(Ti{sub 1-5x}Nb{sub 4x})O{sub 3}. • Addition of niobium can accelerate grain growth of BaTiO{sub 3} ceramics. • Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} presents a dielectric loss of 0.0035 and permittivity value of 54.6. • Electrical measurements showed that Nb{sup 5+} content drops Curie temperature. • Samples with x ⩾ 0.0625 shows an insulating behavior. -- Abstract: In this work, the structural evolution of hexagonal phase Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} by adding Nb{sub 2}O{sub 5} to perovskite structure of BaTiO{sub 3} was investigated. The compositions Ba(Ti{sub 1-5x}Nb{sub 4x})O{sub 3} ceramics, with 0.00025 ⩽ x ⩽ 0.125 were prepared by the conventional solid state route in air atmosphere, the powders precursors, BaTiO{sub 3}, BaCO{sub 3} and Nb{sub 2}O{sub 5}, were mixed in stoichiometric proportions and ground in a ball mill using alumina balls and acetone. The mixed powders were calcined at temperatures up to 1500 °C. The phase transformation of Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} from BaTiO{sub 3} was studied by DRX, Raman spectroscopy, SEM, electrical measurements (relative permittivity and P–E hysteresis loops); Rietveld’s refinement was used to structurally characterize the samples. For the devices obtained capacitance was measured at 1 kHz; with these values we calculated the relative permittivity. The samples show typical P–E hysteresis loops at room temperature accompanied by saturation polarization (Ps) and remnant polarization (Pr). The DRX and Rietveld’s refinement results show x ⩽ 0.01 has a ferroelectric behavior. When the doped level is increased x ⩾ 0.02, a peak displacement is observed, this is due to the phase transformation of tetragonal to cubic into the unit cell. Finally, with x = 0.125 the crystal structure transforms to the characteristic hexagonal phase Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} which

  19. From Ba3Ta5O14N to LaBa2Ta5O13N2: Decreasing the optical band gap of a photocatalyst

    International Nuclear Information System (INIS)

    Anke, B.; Bredow, T.; Pilarski, M.; Wark, M.; Lerch, M.

    2017-01-01

    Yellow LaBa 2 Ta 5 O 13 N 2 was successfully synthesized as phase-pure material crystallizing isostructurally to previously reported Ba 3 Ta 5 O 14 N and mixed-valence Ba 3 Ta V 4 Ta IV O 15 . The electronic structure of LaBa 2 Ta 5 O 13 N 2 was studied theoretically with the range-separated hybrid method HSE06. The most stable structure was obtained when lanthanum was placed on 2a and nitrogen on 4h sites confirming Pauling's second rule. By incorporating nitrogen, the measured band gap decreases from ∼3.8 eV for the oxide via 2.74 eV for Ba 3 Ta 5 O 14 N to 2.63 eV for the new oxide nitride, giving rise to an absorption band well in the visible-light region. Calculated fundamental band gaps confirm the experimental trend. The atom-projected density of states has large contributions from N2p orbitals close to the valence band edge. These are responsible for the observed band gap reduction. Photocatalytic hydrogen formation was investigated and compared with that of Ba 3 Ta 5 O 14 N revealing significantly higher activity for LaBa 2 Ta 5 O 13 N 2 under UV-light. - Graphical abstract: X-ray powder diffraction pattern of LaBa 2 Ta 5 O 13 N 2 with the results of the Rietveld refinements. Inset: Unit cell of LaBa 2 Ta 5 O 13 N 2 and polyhedral representation of the crystal structure. - Highlights: • Synthesis of a new oxide nitride LaBa 2 Ta 5 O 13 N 2 . • Refinement of the crystal structure. • Quantum chemical calculations provided band gap close to the measured value. • New phase shows a higher photocatalytic H 2 evolution rate compared to prior tested Ba 3 Ta 5 O 14 N.

  20. Flora da Paraíba, Brasil: Loganiaceae Flora of Paraíba, Brazil: Loganiaceae

    Directory of Open Access Journals (Sweden)

    Kiriaki Nurit

    2005-06-01

    Full Text Available Neste trabalho apresenta-se o tratamento taxonômico da família Loganiaceae, como parte do projeto "Flora da Paraíba", que vem sendo realizado com o objetivo de identificar e catalogar as espécies da flora local. Realizouse coletas e observações de campo para as identificações, descrições e ilustrações botânicas que foram efetuadas após estudos morfológicos, com o auxílio da bibliografia especializada, complementados pela análise de fotos de tipos, espécimes dos herbários EAN, JPB e IPA, e comparação com material identificado por especialistas. Registrou-se para a Paraíba quatro espécies: Spigelia anthelmia L., com ampla distribuição, e três espécies de Strychnos, somente coletadas em remanescentes de Mata Atlântica, S. atlantica Krukoff & Barneby, S. parvifolia A. DC. e S. trinervis (Vell. Mart.This work constitutes a taxonomic treatment of the Loganiaceae family as part of the project "Flora da Paraíba", which have been carried out with the objective to identify and catalogue the species of the local flora. The botanical identifications and illustrations were made by morphological studies supported by bibliography, analysis of the types, specimens from herbaria EAN, JPB and IPA, and comparison with samples previously identified by specialists, complemented by field observations. Four species of Loganiaceae belonging two genera were found in State of Paraíba: Spigelia anthelmia L. that has wide distribution and three species of Strychnos, found on remains of Atlantic forest, which are S. atlantica Krukoff & Barneby, S. parvifolia A. DC. and S. trinervis (Vell. Mart.

  1. Optical characteristics of BaGa{sub 2}S{sub 4}:Ho{sup 3+} and BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Sung-Hyu [Chosun University, Kwangju (Korea, Republic of); Jin, Moon-Seog [Dongshin University, Naju (Korea, Republic of); Kim, Wha-Tek [Chonnam National University, Kwangju (Korea, Republic of)

    2005-11-15

    BaGa{sub 2}S{sub 4}, BaGa{sub 2}S{sub 4}:Ho{sup 3+}, BaGa{sub 2}Se{sub 4}, and BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the single crystals were investigated in the temperature region from 11 K to 300 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Two broad emission bands were observed in the photoluminescence spectra of the single crystals. These bands were attributed to donor-acceptor pair recombinations. Sharp emission peaks were observed in the BaGa{sub 2}S{sub 4}:Ho{sup 3+} and the BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals and were assigned to radiation recombination between split Stark levels of Ho{sup 3+}.

  2. Non-observation of 12C cluster decay of 114Ba

    International Nuclear Information System (INIS)

    Guglielmetti, A.; Bonetti, R.; Poli, G.; Collatz, R.; Hu, Z.; Kirchner, R.; Roeckl, E.; Gunn, N.; Price, P.B.; Weaver, B.A.; Westphal, A.; California Univ., Berkeley, CA; Szerypo, J.

    1997-10-01

    By means of the on-line mass separator at Gesellschaft fuer Schwerionenforschung, Darmstadt, we produced 114 Ba through the 58 Ni( 58 Ni,2n) reaction, separated it as a 114 Ba 19 F + beam, and implanted it into a stopper foil positioned in the center of an array of track detectors, which were used to search for 12 C radioactivity of 114 Ba. A total number of (5.4±1.7).10 4 114 Ba atoms were implanted. No 12 C event was found after a total exposure time of 116 hours, corresponding to a 58 Ni beam dose of 1.3.10 17 . The resulting upper limit of 3.4.10 -5 (84% c. 1.) for the branching ratio for 12 C decay of 114 Ba is considerably lower than the limits obtained in previous experiments, which represents an inconsistency at levels of more than 90%. A semiempirical estimate of 19.3 MeV for the upper limit of the Q-value for 12 C decay of 114 Ba is derived. (orig.)

  3. Analysis of oxygen binding-energy variations for BaO on W

    Science.gov (United States)

    Haas, G. A.; Shih, A.; Mueller, D.; Thomas, R. E.

    Interatomic Auger analyses have been made of different forms of BaO layers on W substrates. Variations in Auger spectroscopy energies of the Ba4dBa5pO2p interatomic Auger transition were found to be largely governed by the O2p binding energy of the BaO adsorbate. This was illustrated by comparing results of the Auger data values with values derived from O2p binding energies using ultraviolet photoelectron spectroscopy. Very good agreement was observed not only for the W substrate but also for the W substrate which showed two oxygen-induced electronics state. Variations in binding energy were noted for different states of BaO lattice formation and for different amounts of oxidation, ranging from the transition of Ba to BaO and continuing to the BaO 2 stoichiometry and beyond. Effects were also reported for adsorbate alignment and thermal activation (i.e., reduction) of the oxidized state. An empirical relationship was found suggesting that the more tightly bound the O2p states of the BaO adsorbate were, the lower its work function would be. This link between binding energy and work function was observed to be valid not only for cases of poisoning by oxidation, but held as well during reactivation by the subsequent reduction of the oxide. In addition, this relationship also appeared to predict the low work function obtained through the introduction of substances such as Sc to the BaO-W system. Possible qualitative reasons which might contribute to this are discussed in terms of enhanced dipole effects and shifts in band structure.

  4. Optical energy gaps and photoluminescence peaks of BaGa2S4:Er3+ and BaGa2Se4:Er3+ single crystals

    International Nuclear Information System (INIS)

    Choe, Sung-Hyu; Jin, Moon-Seog; Kim, Wha-Tek

    2005-01-01

    BaGa 2 S 4 :Er 3+ and BaGa 2 Se 4 :Er 3+ single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the BaGa 2 S 4 :Er 3+ and the BaGa 2 Se 4 :Er 3+ single crystals were found to be 4.045 eV and 3.073 eV, respectively, at 11 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Sharp emission peaks were observed in the photoluminescence spectra of the single crystals and assigned to radiation recombination between split Stark levels of the Er 3+ ion.

  5. Preparation of Ba1-xSrxWO4 and Ba1-xCaxWO4 films on tungsten plate by mechanically assisted solution reaction at room temperature

    International Nuclear Information System (INIS)

    Rangappa, Dinesh; Fujiwara, Takeshi; Watanabe, Tomoaki; Yoshimura, Masahiro

    2008-01-01

    Preparation of the alkaline earth tungstate films such as Ba 1-x Sr x WO 4 and Ba 1-x Ca x WO 4 on the tungsten substrate was studied with a simple solution process assisted with the ball rotation at room temperature. The solid solution formation and limitations, the effect of oxidizing agent H 2 O 2 and alkaline earth ions concentration on the dissolution of W substrate and the growth of Ba 1-x Sr x WO 4 and Ba 1-x Ca x WO 4 films were studied in detail. The ball rotation assistance plays a very important role to enhance the dissolution of the W substrate and mass transport of the reactant species such as alkaline earth ions and WO 4 2- ions onto the solid/solution interface region, where precipitation occurs. Therefore, the rate of film formation was accelerated by the ball rotation assistance to the reaction system. Ba-rich Ba 1-x Sr x WO 4 and Ba 1-x Ca x WO 4 films were formed without high energy or high temperature treatment

  6. Thermochemical investigations into the system Y-Ba-Cu-O

    International Nuclear Information System (INIS)

    Neuschuetz, D.; Zimmermann, E.; Hack, K.; Boudene, A.; Mohammad, A.

    1992-01-01

    For a consistent thermodynamic description of the quaternary system Y-Ba-Cu-O, the binary and ternary subsystems must be known. The metallic binaries and the ternary system Y-Ba-Cu have been evaluated by the authors. Discrepancies within the Cu-O system made a thorough experimental re-investigation necessary, leading to a new consistent thermodynamic data set for copper-oxygen which can now serve as a basis for the description of phase equilibria of all high temperature superconductors. Extensive experimental work on the ternaries Y-Cu-O and Ba-Cu-O, which are oxygen partial pressure dependent, revealed liquid phases down to 790degC. The ternary Y-Ba-O could be described more easily on the basis of literature values and present experimental results, because it does not contain any liquid phases at relevant temperatures. The representation of the quaternary Y-Ba-Cu-O is complicated both by its dependence on the oxygen potential and the existence of liquid oxide phases. In contrast to common practice, the present investigations had to start from Cu-free Ba-Y-O in order to avoid unknown liquid phases in the experiments. The present results being insufficient for a complete description of the quaternary system, the work is being continued within an EC joint research project. (orig.) With 84 refs., 8 tabs., 47 figs [de

  7. Studi On Oxidation State Of U In Ba2NdUO6

    International Nuclear Information System (INIS)

    Firman Windarto, Hendri

    1996-01-01

    Ba 2 NdUO 6 is not of the important compounds that is formed from a solidification process for high level liquid waste using super high temperature method Ba 2 NdUO 6 has ordered perovskite structure. The objective of this study is to investigate oxidation state of U in Ba 2 NdUO 6 . The properties of Ba 2 NdUO 6 were observed by using Faraday-type torsion magnetometer and X-ray Photoelectron Spectrometer (XPS). The magnetic susceptibility measured in the temperature range of 4K to room temperature showed that the Ba 2 NdUO 6 is paramagnetism that obeys the Curie-Weiss law. The effective moment of Ba 2 NdUO 6 is 3.04 μB. The results of xPs spectrum showed that the peaks of U4f for Ba 2 NdUO 6 appeared exactly between binding energy of UO 2 and UO 3 . It can be concluded that Ba 2 NdUO 6 has binding energy peaks corresponding to pentavalent uranium

  8. Thermoelectric transport properties of BaBiTe{sub 3}-based materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yiming; Zhao, Li-Dong, E-mail: zhaolidong@buaa.edu.cn

    2017-05-15

    BaBiTe{sub 3}, a material with low thermal conductivity, is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. We choose two types of dopants, K and La, trying to optimize its electrical transport properties. The minority carriers, which harm the Seebeck coefficient in this system, are suppressed by La doping. With the increase of both electrical conductivity and Seebeck coefficient, the power factor of 3% La doped BaBiTe{sub 3} reaches 3.7 μW cm{sup −1} K{sup −2} which increased by 40% from undoped BaBiTe{sub 3}. Besides high power factor, the thermal conductivity is also reduced in it. Eventually, a high ZT value, 0.25 at 473 K, for n-type BaBiTe{sub 3} is achieved in 3% La doped BaBiTe{sub 3}. - Graphical abstract: BaBiTe{sub 3} possesses a low thermal conductivity. However, it is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. A high ZT value of 0.25 at 473 K for n-type BaBiTe{sub 3} can be achieved through optimizing electrical transport properties via La doping. - Highlights: • BaBiTe{sub 3} is an analogue of these promising thermoelectric materials: such as CsBi{sub 4}Te{sub 6} and K{sub 2}Bi{sub 8}Se{sub 13}, etc. • BaBiTe{sub 3} possesses a low thermal conductivity. • La is an effective dopant to enhance electrical transport properties. • A high ZT value of 0.25 at 473 K can be achieved in n-type La-doped BaBiTe{sub 3}.

  9. Bound-bound transitions in the emission spectra of Ba+-He excimer

    Science.gov (United States)

    Moroshkin, P.; Kono, K.

    2016-05-01

    We present an experimental and theoretical study of the emission and absorption spectra of the Ba+ ions and Ba+*He excimer quasimolecules in the cryogenic Ba-He plasma. We observe several spectral features in the emission spectrum, which we assign to the electronic transitions between bound states of the excimer correlating to the 6 2P3 /2 and 5 2D3 /2 ,5 /2 states of Ba+. The resulting Ba+(5 2DJ) He is a metastable electronically excited complex with orbital angular momentum L =2 , thus expanding the family of known metal-helium quasimolecules. It might be suitable for high-resolution spectroscopic studies and for the search for new polyatomic exciplex structures.

  10. Er3+ infrared fluorescence affected by spatial distribution synchronicity of Ba2+ and Er3+ in Er3+-doped BaO–SiO2 glasses

    Directory of Open Access Journals (Sweden)

    Atsunobu Masuno

    2016-02-01

    Full Text Available Glasses with the composition xBaO–(99.9 − xSiO2–0.1ErO3/2 (0 ≤x ≤ 34.9 were fabricated by a levitation technique. The glasses in the immiscibility region were opaque due to chemical inhomogeneity, while the other glasses were colorless and transparent. The scanning electron microscope observations and electron probe microanalysis scan profiles revealed that more Er3+ ions were preferentially distributed in the regions where more Ba2+ ions existed in the chemically inhomogeneous glasses. The synchronicity of the spatial distributions of the two ions initially increased with increasing x and then decreased when the Ba2+ concentration exceeded a certain value. The peak shape and lifetime of the fluorescence at 1.55 μm depended on x as well as the spatial distribution of both ions. These results indicate that although ErOn polyhedra are preferentially coordinated with Ba2+ ions and their local structure is affected by the coordination of Ba2+, there is a maximum in the amount of Ba2+ ions that can coordinate ErOn polyhedra since the available space for Ba2+ ions is limited. These findings provide us with efficient ways to design the chemical composition of glasses with superior Er3+ fluorescence properties for optical communication network systems.

  11. Nuclear spectroscopy of doubly-even130,132Ba

    Science.gov (United States)

    Gupta, Anuradha; Gupta, Surbhi; Singh, Suram; Bharti, Arun

    2018-05-01

    A comparative study of some high-spin characteristic nuclear structure properties of doubly-even 130,132Ba nuclei has been made using two microscopic frameworks - CHFB and PSM. The yrast spectra, intrinsic quadrupole moment and deformation systematics of these nuclei have been successfully calculated. Further, the calculated data from both the frameworks is also compared with the available experimental data and a good agreement has been obtained. The present CHFB calculations describes very well the low spin structure of even-even 130,132Ba nuclei whereas PSM calculations provide a qualitative description of the high-spin band structure of doubly-even 130,132Ba nuclei.

  12. Superconductivity in the U(Th)-Y-Ba-Cu-O systems

    International Nuclear Information System (INIS)

    Qin Qizong; He Adi; Jia Weijie; Ma Lidun; Cheng Huansheng; Hua Zhongyi

    1989-01-01

    High T c superconductivity has been observed both resistively and magnetically in the new U(Th)-Y-Ba-Cu-O systems. The zero resistance temperature of the three samples with nominal composition of U 0.1 Y 1.1 Ba 0.8 Cu O 4-z , U 0.15 Y 1.05 Ba 0.8 Cu 4-z and Th 0.3 Y 0.8 Ba 0.8 Cu 4-z is 87K, 79K and 74K, respectively. The result of ac magnetic susceptibility measurement implies that the superconducting state is realized in the U-doped samples below 90K. The stoichimetry of the U-Y-Ba-Cu O superconductors has the aid of Rutherford backscattering and nuclear reaction 16 O(d, p) 17 O. The analytical results show that the 'real composition' of somples may be different from that of the nomial composition. The X ray diffraction analysis of the U-Y-Ba-Cu-O system shows that none of the peaks can be fitted to the uranium oxides and the other raw materiale structure, and its pattern may be attributed to new multiple phases with structure different from the known singlephase superconducting oxides

  13. Genesis and classification of Oxisols in a highland toposequence of the upper Jequitinhonha Valley (MG Gênese e classificação de Latossolos em topossequência das chapadas do alto Vale do Jequitinhonha (MG

    Directory of Open Access Journals (Sweden)

    Celmo Aparecido Ferreira

    2010-02-01

    -morphology indicated prevalence of granular microstructure and porosity with complex stacking patterns.. The soil properties in the toposequence converged to a single soil class, the Oxisols, derived from the same source material. The landscape evolution and genesis of Oxisols of the highlands in the upper Jequitinhonha Valley are related to the evolution of the drainage system and the activity of excavating fauna.O Sistema Brasileiro de Classificação de Solos (SiBCS é um sistema taxonômico, aberto e que se encontra em construção permanente, conforme são obtidos novos conhecimentos sobre solos brasileiros. O objetivo deste trabalho foi efetuar as caracterizações química, física, morfológica, micromorfológica e mineralógica de quatro pedons de Latossolos em topossequência de uma chapada do Alto Vale do Jequitinhonha, enfatizando aspectos de sua gênese, classificação e da evolução da paisagem. Tais pedons ocupam as seguintes posições da vertente: topo - Latossolo Vermelho (LV, terço médio - Latossolo Vermelho-Amarelo (LVA, terço inferior - Latossolo Amarelo (LA e sopé - Latossolo Amarelo, de cor cinzenta, aqui denominado "Latossolo Acinzentado" ("LAC". Esses pedons foram descritos e amostrados para caracterização com análises químicas e físicas de rotina. Os teores totais de Fe, Ti, Al, Mn e Si foram determinados pelo método do ataque sulfúrico, e os óxidos de Fe, Al e Mn foram avaliados nos extratos de ditionito-citrato-bicarbonato e oxalato. A mineralogia das argilas silicatadas foi identificada pela difratometria de raios X, e a dos óxidos de Fe, pela difratometria diferencial de raios X. Por espectrometria de fluorescência de raios X, foram determinados os teores totais de Ti, Ga e Zr. O "LAC" apresentou cores acinzentadas e significativos fragmentos de unidades estruturais na forma de uma massa adensada, característica de Gleissolos, nos horizontes A e BA. Todos os pedons são muito argilosos, distróficos, com baixos teores de P disponível e p

  14. Punta Pitt, Galapagos Ba/Ca Data for 1963-1982

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — File contains Ba/Ca data (in mmol/mol) presented by Lea et al. (1989). Samples were measured at the Massachusetts Institute of Technology by D. Lea. Ba...

  15. Determination of the UO2-ZrO2-BaO equilibrium diagram

    International Nuclear Information System (INIS)

    Paschoal, J.O.A.; Kleykanp, H.; Thuemmler, F.

    1984-01-01

    It is determined the equilibrium diagram of UO 2 - ZrO 2 - BaO to interpret and predict changes in the chemical properties of ceramic (oxide) nuclear fuels during irradiation. The isothermal section of the system at 1700 0 C was determined experimentally, utilizing the techniques of ceramography, X-ray diffraction analysis, microprobe analysis and differential thermal analysis. The solid solubility limits at 1700 0 C between UO 2 and ZrO 2 , UO 2 and BaO, ZrO 2 and BaO, ZrO 2 and BaO and BaUO 3 and BaZrO 3 is presented. The influence of oxygen potential in relation to the different phases is discussed and the phase diagram of the system presented. (M.C.K.) [pt

  16. Left posterior BA37 is involved in object recognition: a TMS study

    DEFF Research Database (Denmark)

    Stewart, Lauren; Meyer, Bernd-Ulrich; Frith, Uta

    2001-01-01

    Functional imaging studies have proposed a role for left BA37 in phonological retrieval, semantic processing, face processing and object recognition. The present study targeted the posterior aspect of BA37 to see whether a deficit, specific to one of the above types of processing could be induced...... to name pictures when TMS was given over lBA37 compared to vertex or rBA37. rTMS over lBA37 had no significant effect on word reading, nonword reading or colour naming. The picture naming deficit is suggested to result from a disruption to object recognition processes. This study corroborates the finding...... from a recent imaging study, that the most posterior part of left hemispheric BA37 has a necessary role in object recognition....

  17. Particle-hole states in 138Ba

    International Nuclear Information System (INIS)

    Bondarenko, V.A.; Khitrov, V.A.; Popov, Yu.P.; Brant, S.; Paar, V.; Simicic, L.

    1995-01-01

    The thermal-neutron-capture gamma rays and γγ-coincidences were measured by means of Ge detectors. Using primary and secondary (n, γ) data, the level scheme of 138 Ba was established with 63 levels up to an excitation energy of 5 MeV. The level energies and (d, p) transfer data were compared with model predictions of the interacting boson-fermion-fermion model. As shown, this model provides a basic understanding of the neutron particle-hole states of 138 Ba in the energy range of 3.5-5.0 MeV. ((orig.))

  18. The BaBar Data Acquisition System

    CERN Document Server

    Scott, I; Grosso, P; Huffer, M E; O'Grady, C; Russell, J J

    1999-01-01

    The BaBar experiment at the Stanford Linear Accelerator Center is designed to perform a search for CP violation by ana-lyzing the decays of a very large sample of B and B(Bar) mesons produced at the high luminosity PEP-II accelerator. The data acquisition system must cope with a sustained high event rate, while supporting real time feature extraction and data compression with minimal dead time. The BaBar data acquisition system is based around a common VME interface to the electronics read-out of the separate detec-tor subsystems. Data from the front end electronics is read into commercial VME processors via a custom "Personality Card" and PCI interface. The commercial CPUs run the Tornado operating system to provide a platform for detector subsystem code to perform the necessary data processing. The data is read out via a non-blocking network switch to a farm of commercial UNIX processors. The current implementation of the BaBar data acquisition sys-tem has been shown to sustain a Level 1 trigger rate of 1.3...

  19. DELIMITAÇÃO E PROTEÇÃO DAS ÁREAS DE PRESERVAÇÃO PERMANENTE DE CHAPADAS: ESTUDO DE CASO DA MINERAÇÃO DE AREIA EM ENCOSTAS NO NORTE DE MINAS GERAIS

    Directory of Open Access Journals (Sweden)

    Vitor Vieira Vasconcelos

    2011-12-01

    Full Text Available A mineração de areia de encosta para construção civil, na região Norte de Minas Gerais, tem causado uma séria de conflitos sócio-ambientais. A Polícia Ambiental e os órgãos de licenciamento ambiental têm encontrado dificuldades técnicas e administrativas para lidar com a situação. Este artigo apresenta uma proposta de utilização de técnicas de geoprocessamento e topografia, integradas à interpretação do direito ambiental, com fins de abordar os problemas citados de forma mais eficiente. Enfatiza-se, especialmente, a delimitação e a proteção de Áreas de Preservação Permanente de bordas de chapadas, onde ocorre tipicamente a mineração de areia de encosta. Por fim, apresentam-se propostas que auxiliem na transição para um modelo mais sustentável da mineração para construção civil na Região Norte de Minas Gerais.

  20. Proton microbeam irradiation effects on PtBA polymer

    Indian Academy of Sciences (India)

    Microbeam irradiation effects on poly-tert-butyl-acrylate (PtBA) polymer using 2.0 MeV proton microbeam are reported. Preliminary results on pattern formation on PtBA are carried out as a function of fluence. After writing the pattern, a thin layer of Ge is deposited. Distribution of Ge in pristine and ion beam patterned surface ...

  1. The 226Ra-Ba relationship in the North Atlantic during GEOTRACES-GA01

    Science.gov (United States)

    Le Roy, Emilie; Sanial, Virginie; Charette, Matthew A.; van Beek, Pieter; Lacan, François; Jacquet, Stéphanie H. M.; Henderson, Paul B.; Souhaut, Marc; García-Ibáñez, Maribel I.; Jeandel, Catherine; Pérez, Fiz F.; Sarthou, Géraldine

    2018-05-01

    We report detailed sections of radium-226 (226Ra, T1/2 = 1602 years) activities and barium (Ba) concentrations determined in the North Atlantic (Portugal-Greenland-Canada) in the framework of the international GEOTRACES program (GA01 section - GEOVIDE project, May-July 2014). Dissolved 226Ra and Ba are strongly correlated along the section, a pattern that may reflect their similar chemical behavior. Because 226Ra and Ba have been widely used as tracers of water masses and ocean mixing, we investigated their behavior more thoroughly in this crucial region for thermohaline circulation, taking advantage of the contrasting biogeochemical patterns existing along the GA01 section. We used an optimum multiparameter (OMP) analysis to distinguish the relative importance of physical transport (water mass mixing) from nonconservative processes (sedimentary, river or hydrothermal inputs, uptake by particles and dissolved-particulate dynamics) on the 226Ra and Ba distributions in the North Atlantic. Results show that the measured 226Ra and Ba concentrations can be explained by conservative mixing for 58 and 65 % of the samples, respectively, notably at intermediate depth, away from the ocean interfaces. 226Ra and Ba can thus be considered conservative tracers of water mass transport in the ocean interior on the space scales considered here, namely, on the order of a few thousand kilometers. However, regions in which 226Ra and Ba displayed nonconservative behavior and in some cases decoupled behaviors were also identified, mostly at the ocean boundaries (seafloor, continental margins and surface waters). Elevated 226Ra and Ba concentrations found in deepwater in the West European Basin suggest that lower Northeast Atlantic Deep Water (NEADWl) accumulates 226Ra and Ba from sediment diffusion and/or particle dissolution during transport. In the upper 1500 m of the West European Basin, deficiencies in 226Ra and Ba are likely explained by their incorporation in planktonic calcareous

  2. Tritellurides of comples cations: Synthesis and crystal structure of (Ba(en)/sub 3/)Te/sub 3/ and (Ba(en)/sub 4,5/)Te/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Zagler, R; Eisenmann, B; Schaefer, H

    1987-02-01

    The two title compounds have been prepared by reaction of appropriate mixtures of the elements in ethylenediamine. The structures have been determined on the basis of single crystal data. (Ba(en)/sub 3/Te/sub 3/ crystallizes in the monoclinic system, space group P2/sub 1/c with a = 918.0(4), b = 1203.7(6), c = 1639,9(6) pm, ..beta.. = 93.4(1)/sup 0/. In the structure there are bent tritelluride anions Te/sub 3//sup 2 -/ (bond lengths 273,9-278,5 pm, bond angle (105.7/sup 0/). The Ba/sup 2 +/ cations are six coordinate by the bidentate ligand ethylenediamine. (Ba(en)/sub 4,5/)Te/sub 3/ crystallizes in the monoclinic system, space group Cc with a = 1752.8(6), b = 938.9(4), c = 3041.7(8) pm, ..beta.. = 91.3(1)/sup 0/. In this structure the bond lengths in the TE/sub 3//sup 2 -/ anions are shorter (272.1-273.1 pm, bond angles 110.9-112.2/sup 0/). The cations are coordinated by four bidentate ligands, and are connected into pairs by a further ethylenediamine molecule. The resulting dinuclear (Ba(en)/sub 4/)en(Ba(en)/sub 4/)/sup 4 +/ units have the Ba/sup 2 +/ cations in CN 9.

  3. Earth Observation for Biodiversity Assessment (EO-BA)

    CSIR Research Space (South Africa)

    Cho, Moses A

    2012-10-01

    Full Text Available in the Dukuduku coastal forest Earth Observation for Biodiversity Assessment (EO-BA) MA CHO, P DEBBA, R MATHIEU, A RAMOELO, L NAIDOO, H VAN DEVENTER, O MALAHLELA AND R MAIN CSIR Natural Resources and the Environment, Pretoria, South Africa PO Box 395... Observation for Biodiversity Assessment (EO-BA) programme is designed to enhance biodiversity assessment and conservation through the application of earth observation data, with particular focus on the African continent. MISSION To initiate and develop...

  4. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN P-00...

  5. Characterization of the insulator barrier and the superconducting transition temperature in GdBa2Cu3O7−δ/BaTiO3 bilayers for application in tunnel junctions

    International Nuclear Information System (INIS)

    Navarro, H.; Sirena, M.; Haberkorn, N.; Yang, Ilkyu; Kim, Jeehoon

    2015-01-01

    The optimization of the superconducting properties in a bottom electrode and the quality of an insulator barrier are the first steps in the development of superconductor/insulator/superconductor tunnel junctions. Here, we study the quality of a BaTiO 3 tunnel barrier deposited on a 16 nm thick GdBa 2 Cu 3 O 7−δ thin film by using conductive atomic force microscopy. We find that the tunnel current is systematically reduced (for equal applied voltage) by increasing the BaTiO 3 barrier thickness between 1.6 and 4 nm. The BaTiO 3 layers present an energy barrier of ≈1.2 eV and an attenuation length of 0.35–0.5 nm (depending on the applied voltage). The GdBa 2 Cu 3 O 7−δ electrode is totally covered by a BaTiO 3 thickness above 3 nm. The presence of ferroelectricity was verified by piezoresponse force microscopy for a 4 nm thick BaTiO 3 top layer. The superconducting transition temperature of the bilayers is systematically suppressed by increasing the BaTiO 3 thickness. This fact can be associated with stress at the interface and a reduction of the orthorhombicity of the GdBa 2 Cu 3 O 7−δ . The reduction in the orthorhombicity is expected by considering the interface mismatch and it can also be affected by reduced oxygen stoichiometry (poor oxygen diffusion across the BaTiO 3 barrier)

  6. Left cytoarchitectonic BA 44 processes syntactic gender violations in determiner phrases.

    Science.gov (United States)

    Heim, Stefan; van Ermingen, Muna; Huber, Walter; Amunts, Katrin

    2010-10-01

    Recent neuroimaging studies make contradictory predictions about the involvement of left Brodmann's area (BA) 44 in processing local syntactic violations in determiner phrases (DPs). Some studies suggest a role for BA 44 in detecting local syntactic violations, whereas others attribute this function to the left premotor cortex. Therefore, the present event-related functional magnetic resonance imaging (fMRI) study investigated whether left-cytoarchitectonic BA 44 was activated when German DPs involving syntactic gender violations were compared with correct DPs (correct: 'der Baum'-the[masculine] tree[masculine]; violated: 'das Baum'--the[neuter] tree[masculine]). Grammaticality judgements were made for both visual and auditory DPs to be able to generalize the results across modalities. Grammaticality judgements involved, among others, left BA 44 and left BA 6 in the premotor cortex for visual and auditory stimuli. Most importantly, activation in left BA 44 was consistently higher for violated than for correct DPs. This finding was behaviourally corroborated by longer reaction times for violated versus correct DPs. Additional brain regions, showing the same effect, included left premotor cortex, supplementary motor area, right middle and superior frontal cortex, and left cerebellum. Based on earlier findings from the literature, the results indicate the involvement of left BA 44 in processing local syntactic violations when these include morphological features, whereas left premotor cortex seems crucial for the detection of local word category violations. © 2010 Wiley-Liss, Inc.

  7. Luminescent properties of BaCl2-Eu microcrystals embedded in a CsI matrix

    International Nuclear Information System (INIS)

    Pushak, A.; Vistovskyy, V.; Voloshinovskii, A.; Savchyn, P.; Antonyak, O.; Demkiv, T.; Dacyuk, Yu.; Myagkota, S.; Gektin, A.

    2013-01-01

    The spectral-luminescent properties of CsI-BaCl 2 (1 mol%)-Eu(0.02 mol%) crystalline system are studied. Europium ion doped BaCl 2 microcrystals embedded in a CsI matrix are revealed on CsI-BaCl 2 (1 mol%)-Eu(0.02 mol%) freshly cleaved surface by the scanning electron microscopy. The size of microcrystals is shown to be within 0.5–5 microns. The luminescent parameters of the BaCl 2 -Eu 2+ microcrystals are shown to be similar to ones of a single crystal analogue. The 4f → 5d absorption transitions in europium ions and the reabsorption of the intrinsic emission of the CsI host are the main excitation mechanisms of europium luminescence in the BaCl 2 microcrystals. -- Highlights: ► The formation of chloride BaCl 2 :Eu microcrystals in the case of BaCl 2 doped CsI crystal has been revealed. ► The observed size of microcrystals at BaCl 2 concentration of 1% is about 0.5–5 μm. ► Majority of Eu 2+ ions in CsI-BaCl 2 -EuCl 3 crystalline system enters into BaCl 2 microcrystals. ► The luminescent parameters of the BaCl 2 :Eu 2+ microcrystals and its bulk analogue are similar

  8. Quo Vadis the B.A. degree: Perceptions and visions1

    Directory of Open Access Journals (Sweden)

    Annette L. Combrink

    1993-03-01

    Full Text Available Today is a very special day for all the graduates assembled to have a B.A. degree conferred on them. It is a day on which to celebrate the reward for hard work and for realized dreams. This is a very homogeneous group of people - in the sense that they will be receiving B.A. degrees, and for that reason it would be highly apposite to share some cherished thought and ideas about the B.A. degree.

  9. THINNING OF ‘GALA’ AND 'GOLDEN DELICIOUS' APPLES WITH BA, NAA AND THEIR COMBINATIONS

    Directory of Open Access Journals (Sweden)

    M STOPAR

    2002-07-01

    Full Text Available Apple trees, eight-year-old ‘Gala’/M.9 and four-year-old ‘Golden Delicious’/M.9 have been thinned with 6- benzyladenine (BA 50 ppm, 100 ppm and 200 ppm, with 1-naphthaleneacetic acid (NAA 5 ppm, 10 ppm and 20 ppm, and with the tank mix combinations of BA 50 ppm + NAA 5 ppm or BA 20 ppm + NAA 5 ppm, all at 9-10 mm fruitlet diameter. All applied concentrations of BA and NAA thinned both cultivars significantly and no significant difference was found between BA or NAA thinning action. No concentration response on thinning was observed with neither BA nor NAA application. All BA or NAA separate treatments caused yield of fruit to shift to bigger size class. The only concentration response effect was found on evaluation of mean fruit weight data on ‘Golden Delicious’. The higher concentration of BA was used, the higher was the weight of ‘Golden Delicious’ fruit. On the opposite, the higher concentration of NAA was used, the lower was the weight of ‘Golden Delicious’ fruit (not significantly. When BA and NAA were sprayed on ‘Gala’ or ‘Golden Delicious’ as a tank mix combination, similar effect on thinning or fruit growth occurred comparing to BA or NAA when sprayed alone. Return bloom was enhanced on all thinned ‘Gala’ trees while flower formation of ‘Golden Delicious’ was better in the case of BA 200 ppm, NAA 5 ppm, NAA 20 ppm or tank mix spraying of BA 20 ppm + NAA 5 ppm.

  10. Application of NAA and BA in chemical thinning of some commercial apple cultivars

    Directory of Open Access Journals (Sweden)

    Šebek Gordana

    2015-01-01

    Full Text Available This paper presents the fruit thinning response of some commercial apple cultivars to NAA and BA plant regulators. The experiment was designed to evaluate NAA applied separately at three concentrations - 13.2 ppm, 17.82 ppm and 26.73 ppm, and BA + NAA combinations (BA - 60 ppm, 100 ppm, 120 ppm or 140 ppm + NAA 4.29 ppm for thinning the assessed apple cultivars. All treatments with NAA and BA + NAA adequately thinned 'McIntosh' and 'Jonathan', whereas the application of NAA 17.82 ppm and 26.73 ppm and the combined treatment BA 140 ppm+ NAA 4.29 ppm were effective fruit thinners for 'Prima'. In terms of the average fruit weight, number of fruits categorized as large (> 75 mm or > 65 mm, and number of fruit per trunk cross-sectional area, the treatment BA 140 ppm + NAA 4.29 ppm was most effective on 'McIntosh' and 'Prima', whereas BA 100 ppm + NAA 4.29 ppm had the best effect on 'Jonathan'.

  11. Epitaxial thin-film growth of Ruddlesden-Popper-type Ba{sub 3}Zr{sub 2}O{sub 7} from a BaZrO{sub 3} target by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Butt, Shariqa Hassan; Rafique, M.S.; Siraj, K.; Latif, A.; Afzal, Amina [University of Engineering and Technology, Laser and Optronics Centre, Department of Physics, Lahore (Pakistan); Awan, M.S. [Ibn-e-Sina Institute of Science and Technology (ISIT), Islamabad (Pakistan); Bashir, Shazia [Government College University, Centre for Advanced Studies in Physics, Lahore (Pakistan); Iqbal, Nida [Universiti Teknologi Malaysia, Medical Devices and Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Johor Bahru, Johor (Malaysia)

    2016-07-15

    Ruddlesden-Popper Ba{sub 3}Zr{sub 2}O{sub 7} thin films have been synthesized via pulsed laser deposition (PLD) technique. The optimization of deposition parameters in PLD enables the formation of thin film of metastable Ba{sub 3}Zr{sub 2}O{sub 7} phase from BaZrO{sub 3} target. In order to see the post-annealing effects on the structural and optical properties, the deposited Ba{sub 3}Zr{sub 2}O{sub 7} thin films were annealed at 500, 600 and 800 C. X-ray diffraction (XRD) reveals the formation of Ba{sub 3}Zr{sub 2}O{sub 7} phase with tetragonal structure. The changes in the surface of the deposited films were analysed by FE-SEM and AFM. The thin film post-annealed at 500 C exhibited the best structural, optical and surface properties. Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. The XPS results show that Ba, Zr and O exist mainly in the form of Ba{sub 3}Zr{sub 2}O{sub 7} Ruddlesden-Popper-type perovskite structure. (orig.)

  12. Baština Starog grada Zrinskih

    OpenAIRE

    Kovač, Ivana

    2017-01-01

    Stari grad Zrinskih priča bogate, zanimljive i velike priče u svakom svojem kutku. Dvorac je prepun kulturne baštine koja će svakog ostaviti bez daha i dat će nam nove poglede na hrvatsku povijest, a još više na međimursku povijest. U ovom završnom radu pisat ću o ljepotama kraja, povijesnim zbivanjima i kulturnoj baštini grada, od samog početka pa do danas. Posebno ću se posvetiti predmetima koji su nam ostavili naši preci, a najviše umjetnosti grada i okolice. Čakovečki stari grad ima djelo...

  13. Magnetic and electrical properties in BaNiS2-type solid solutions

    International Nuclear Information System (INIS)

    Irizawa, Akinori; Yoshimura, Kazuyoshi; Kosuge, Koji

    2000-01-01

    The magnetic and electrical properties are reported in the new solid solutions BaCo 1-x Cu x S 2 and BaNi 1-x Fe x S 2 . Both compounds show spin-glass-like behavior, although the type of spin frustrations is different with each other. BaCo 1-x Cu x S 2 shows a competition type spin-glass behavior with reentrant phenomenon from antiferromagnetic to spin-glass at low temperatures. BaNi 1-x Fe x S 2 shows a dilute type spin-glass behavior together with super-paramagnetic properties. The temperature variation of 57 Fe Moessbauer spectra in BaNi 0.8 Fe 0.2 S 2 is explicable in a framework of cluster-glass. (author)

  14. Photoluminescence properties of BaMoO4 amorphous thin films

    International Nuclear Information System (INIS)

    Marques, Ana Paula Azevedo; Melo, Dulce M.A. de; Longo, Elson; Paskocimas, Carlos A.; Pizani, Paulo S.; Leite, Edson R.

    2005-01-01

    BaMoO 4 amorphous and crystalline thin films were prepared from polymeric precursors. The BaMoO 4 was deposited onto Si wafers by means of the spinning technique. The structure and optical properties of the resulting films were characterized by FTIR reflectance spectra, X-ray diffraction (XRD), atomic force microscopy (AFM) and optical reflectance. The bond Mo-O present in BaMoO 4 was confirmed by FTIR reflectance spectra. XRD characterization showed that thin films heat-treated at 600 and 200 deg. C presented the scheelite-type crystalline phase and amorphous, respectively. AFM analyses showed a considerable variation in surface morphology by comparing samples heat-treated at 200 and 600 deg. C. The reflectivity spectra showed two bands, positioned at 3.38 and 4.37 eV that were attributed to the excitonic state of Ba 2+ and electronic transitions within MoO 2- 4 , respectively. The optical band gaps of BaMoO 4 were 3.38 and 2.19 eV, for crystalline (600 deg. C/2 h) and amorphous (200 deg. C/8 h) films, respectively. The room-temperature luminescence spectra revealed an intense single-emission band in the visible region. The PL intensity of these materials was increased upon heat-treatment. The excellent optical properties observed for BaMoO 4 amorphous thin films suggested that this material is a highly promising candidate for photoluminescent applications

  15. Stability of Tl-Ba-Ca-Cu-O superconducting thin films

    International Nuclear Information System (INIS)

    Siegal, M. P.; Overmyer, D. L.; Venturini, E. L.; Padilla, R. R.; Provencio, P. N.

    1999-01-01

    We report the stability of TlBa 2 CaCu 2 O 7 and Tl 2 Ba 2 CaCu 2 O 8 on LaAlO 3 (100) epitaxial thin films, under a variety of conditions. All films are stable in acetone and methanol and with repeated thermal cycling to cryogenic temperatures. Moisture, especially vapor, degrades film quality rapidly. These materials are stable to high temperatures in either N 2 or O 2 ambients. While total degradation, resulting from Tl depletion, occurs at the same temperatures for both phases, 600 degree sign C in N 2 and 700 degree sign C in O 2 , the onset of degradation occurs at somewhat lower temperatures for TlBa 2 CaCu 2 O 7 than for Tl 2 Ba 2 CaCu 2 O 8 . (c) 1999 Materials Research Society

  16. Performance simulation of BaBar DIRC bar boxes in TORCH

    Science.gov (United States)

    Föhl, K.; Brook, N.; Castillo García, L.; Cussans, D.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Harnew, N.; Piedigrossi, D.; Rademacker, J.; Ros García, A.; van Dijk, M.

    2017-12-01

    TORCH is a large-area precision time-of-flight detector based on the DIRC principle. The DIRC bar boxes of the BaBar experiment at SLAC could possibly be reused to form a part of the TORCH detector time-of-flight wall area, proposed to provide positive particle identification of low momentum kaons in the LHCb experiment at CERN. For a potential integration of BaBar bar boxes into TORCH, new imaging readout optics are required. From the several designs of readout optics that have been considered, two are used in this paper to study the effect of BaBar bar optical imperfections on the detector reconstruction performance. The kaon-pion separation powers obtained from analysing simulated photon hit patterns show the performance reduction for a BaBar bar of non-square geometry compared to a perfectly rectangular cross section.

  17. Synthesis, Crystal Structure, and Chemical-Bonding Analysis of BaZn(NCN2

    Directory of Open Access Journals (Sweden)

    Alex J. Corkett

    2017-12-01

    Full Text Available The ternary carbodiimide BaZn(NCN2 was prepared by a solid-state metathesis reaction between BaF2, ZnF2, and Li2NCN in a 1:1:2 molar ratio, and its crystal structure was determined from Rietveld refinement of X-ray data. BaZn(NCN2 represents the aristotype of the LiBa2Al(NCN4 structure which is unique to carbodiimide/cyanamide chemistry and is well regarded as being constructed from ZnN4 tetrahedra, sharing edges and vertices through NCN2− units to form corrugated layers with Ba2+ in the interlayer voids. Structural anomalies in the shape of the cyanamide units are addressed via IR spectrometry and DFT calculations, which suggest the presence of slightly bent N=C=N2− carbodiimide units with C2v symmetry. Moreover, chemical-bonding analysis within the framework of crystal orbital Hamilton population (COHP reveals striking similarities between the bonding interactions in BaZn(NCN2 and SrZn(NCN2 despite their contrasting crystal structures. BaZn(NCN2 is only the second example of a ternary post-transition metal carbodiimide, and its realization paves the way for the preparation of analogues featuring divalent transition metals at the tetrahedral Zn2+ site.

  18. Design, synthesis and luminescence properties of Ba2 YB2 O6 Cl- and Ba2 YB2 O6 F-based phosphors.

    Science.gov (United States)

    Chen, Wanping; Yang, Xin; Liu, Yan; Dai, Xiaoyan

    2015-05-01

    Using a high-temperature solid-state reaction, the chlorine in Ba2 YB2 O6 Cl is gradually replaced by F, and a new compound with the nominal chemical formula Ba2 YB2 O6 F and two phosphors doped with Ce(3+) and Eu(3+) , respectively, are obtained. X-Ray diffraction and photoluminescence spectroscopy are used to characterize the as-synthesized samples. The as-synthesized Ba2 YB2 O6 Cl exhibits bright blue emission in the spectral range ~ 330-410 nm with a maximum around 363 nm under X-ray or UV excitation. Ba2 YB2 O6 F:0.01Ce(3+) exhibits blue emission in the range ~ 340-570 nm with a maximum around 383 nm. Ba2 YB2 O6 F:0.01Eu(3+) exhibits a predominantly (5) D0 -(7)  F2 emission (~610 nm) and the relative intensities of the (5) D0 -(7)  F0,1,2 emissions are tunable under different wavelength UV excitation. The luminescence behaviors of the two phosphors are explained simply in terms of the host composition and site occupancy probability of Ce(3+) and Eu(3+) , respectively. The results indicate that these phosphors have potential application as a blue phosphor or as a red phosphor. Copyright © 2014 John Wiley & Sons, Ltd.

  19. How Extended Is Wernicke’s Area? Meta-Analytic Connectivity Study of BA20 and Integrative Proposal

    Directory of Open Access Journals (Sweden)

    Alfredo Ardila

    2016-01-01

    Full Text Available Understanding the functions of different brain areas has represented a major endeavor of contemporary neurosciences. The purpose of this paper was to pinpoint the connectivity of Brodmann area 20 (BA20 (inferior temporal gyrus, fusiform gyrus in language tasks. A meta-analysis was conducted to assess the language network in which BA20 is involved. The DataBase of Brainmap was used; 11 papers corresponding to 12 experimental conditions with a total of 207 subjects were included in this analysis. Our results demonstrated seven clusters of activation including other temporal lobe areas (BA3, BA21, the insula, and the prefrontal cortex; minor clusters in the cingulate gyrus and the occipital lobe were observed; however, the volumes of all the activation clusters were small. Our results suggest that regardless of BA20 having certain participation in language processes it cannot be considered as a core language processing area (Wernicke’s area; nonetheless, it could be regarded as kind of language processing marginal area, participating in “extended Wernicke’s area” or simply “Wernicke’s system.” It is suggested that “core Wernicke’s area” roughly corresponds to BA21, BA22, BA41, and BA42, while a “language associations area” roughly corresponds to BA20, BA37, BA38, BA39, and BA40 (“extended Wernicke’s area” or “Wernicke’s system”.

  20. Strain induced enhancement of magnetization in Ba{sub 2}FeMoO{sub 6} based heterostructure with (Ba{sub x}Sr{sub 1-x})TiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyeong-Won; Norton, David P. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Ghosh, Siddhartha, E-mail: ghoshsid@gmail.com; Buvaev, Sanal; Hebard, Arthur F. [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States)

    2016-05-14

    High quality epitaxial Ba{sub 2}FeMoO{sub 6} thin films and Ba{sub 2}FeMoO{sub 6}–(Ba{sub x}Sr{sub 1−x})TiO{sub 3} bi-layer (BL) and superlattice (SL) structures were grown via pulsed laser deposition under low oxygen pressure, and their structural, magnetic, and magneto-transport properties were examined. Superlattice and bi-layer structures were confirmed by X-ray diffraction patterns. Low temperature magnetic measurement shows that the saturation magnetization (M{sub S}) is significantly higher for SLs and almost similar or lower for BLs, when compared to phase pure Ba{sub 2}FeMoO{sub 6} thin films. The variation of the coercive field (H{sub C}) follows exact opposite trend, where BL samples have higher H{sub C} and SL samples have lower H{sub C} than pure Ba{sub 2}FeMoO{sub 6} thin films. Also, a significant decrease of the Curie temperature is found in both BL and SL structures compared to pure Ba{sub 2}FeMoO{sub 6} thin films. Negative magneto-resistance is seen in all the BL and SL structures as well as in pure Ba{sub 2}FeMoO{sub 6} thin films. In contrast to the magnetic properties, the magneto-transport properties do not show much variation with induced strain.

  1. Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

    International Nuclear Information System (INIS)

    Wang, S.F.; Li, Q.; Zu, X.T.; Xiang, X.; Liu, W.; Li, S.

    2016-01-01

    (Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M"2"+ ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe_2O_4 magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe_2O_4 of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly. - Graphical abstract: Schematic representation of the proposed model for MFe_2O_4 nanoparticle synthesis, starting from EDTA-chelated M"2"+ (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

  2. The relationship of structure to superconductivity in the Pr-Ba-Cu-O system

    Science.gov (United States)

    Minseo, P.

    1994-05-01

    The relation of structure to lack of superconductivity in Pr-Ba-Cu-O was systematically investigated. First, the phase equilibria of this system was studied to find the processing parameters which maximize the cation-site ordering between Pr and Ba ions. Second, a comparative study between superconducting Nd-Ba-Cu-O and nonsuperconducting Pr-Ba-Cu-O was performed by forming solid-solution Nd-Pr-Ba-Cu-O. The relation between structure and superconductivity in Nd(1-x)Pr(x)Ba2Cu3O(7-delta) is investigated. T sub c decreases monotonically with increasing x and superconductivity disappears at around x = 0.3 to 0.4. T sub c is enhanced by 10 K when the sample is processed at an oxygen partial pressure (PO2) of 0.01 atm, followed by oxygenation at 450 C. Depression of T sub c as a function of x and PO2 is explained in terms of a charge-transfer model. It is suggested that destruction of superconductivity in the RE(1-x)Pr(x)Ba2Cu3O(7-delta) (RE=rare-earth) system can be viewed as disruption of four-fold planar coordinated Cu ions in the chain-site due to permanent occupation of extra Pr ions on Ba sites.

  3. CONTRAST STUDY ON CT AND BA IN DIAGNOSIS OF PATIENTS WITH ATHEROTHROMBOTIC BRAIN INFARCTION

    Institute of Scientific and Technical Information of China (English)

    Mingshun Liu; Haixiang Gao; Xiaomei Fu; Po Ma

    2007-01-01

    Objectives: To explore applied value on CT and BA in diagnosis of patients with atherothrombotic brain infarction. Methods:CT and BA were examined in 246 patients with atherothrombotic brain infarction. Results:The different change of CT and BA were showed in 246 patients with atherothrombotic brain infarction. Conclusions: There were separately different advantage and shortcoming in CT and BA in diagnosis of atherothrombotic brain infarction. The value of clinical application of BA was important in diagnosis of atherothrombotic brain infarction.

  4. Effect of lithium doping in BaTiO3 ceramics for vibration sensor application

    Science.gov (United States)

    Praveen, E.; Murugan, S.; Jayakumar, K.

    2018-04-01

    Phase pure undoped and Lithium doped BaTiO3 particles have been synthesized by high temperature solid-state reaction method. Substitution of Lithium at the Ba2+ site in BaTiO3 lattice has been investigated. The structural, vibrational, electrical and mechanical characterization have been carried out. The poled samples were used as a sensing element for the detection of mechanical oscillations and the presence of 80 Hz pulse in the output spectrum manifest the response of the sensor element to the applied mechanical stress. In comparison with pure BaTiO3 the sensitivity of Li doped BaTiO3 is 14 times greater than the pure BaTiO3. This confirms that Li doped BaTiO3 could be an efficient candidate for the functionalization of vibration sensors in space application.

  5. Growth of BaTiO3-PVDF composite thick films by using aerosol deposition

    Science.gov (United States)

    Cho, Sung Hwan; Yoon, Young Joon

    2016-01-01

    Barium titanate (BaTiO3)-polyvinylidene fluoride (PVDF) composite thick films were grown by using aerosol deposition at room temperature with BaTiO3 and PVDF powders. To produce a uniform composition in ceramic and polymer composite films, which show a substantial difference in specific gravity, we used PVDF-coated BaTiO3 powders as the starting materials. An examination of the microstructure confirmed that the BaTiO3 were well distributed in the PVDF matrix in the form of a 0 - 3 compound. The crystallite size in the BaTiO3-PVDF composite thick films was 5 ˜ 50 times higher than that in pure BaTiO3 thick films. PVDF plays a role in suppressing the fragmentation of BaTiO3 powder during the aerosol deposition process and in controlling the relative permittivity.

  6. Glass formation and physicochemical properties of glasses of Ba(PO3)2-LiRAlF6 (R=Mg, Ca, Sr, Ba) system

    International Nuclear Information System (INIS)

    Khalilev, V.D.; Chkhenkeli, G.D.; Vakhrameev, V.I.

    1987-01-01

    Glass formation regions, crystallizability, optical constants, thermal linear expansion coefficient and IR absorption spectra of glass are studied in Ba(PO) 3 ) 2 - LiRAlF 6 system where R=Mg, Ca, Sr, Ba. The carried out investigation confirms participation of introduced fluorides (as modified cryolites) in structural transformations manifested in increase of glass formation regions and nonlinear variations of properties

  7. Crystallization of the HigBA2 toxin-antitoxin complex from Vibrio cholerae

    DEFF Research Database (Denmark)

    Hadǽi, San; Garcia-Pino, Abel; Martinez-Rodriguez, Sergio

    2013-01-01

    The genome of Vibrio cholerae encodes two higBA toxin-antitoxin (TA) modules that are activated by amino-acid starvation. Here, the TA complex of the second module, higBA2, as well as the C-terminal domain of the corresponding HigA2 antitoxin, have been purified and crystallized. The HigBA2 compl...

  8. Superconductivity of Ba8Si46-xGax clathrates

    Science.gov (United States)

    Li, Yang; Zhang, Ruihong; Chen, Ning; Ma, Xingqiao; Cao, Guohui; Luo, Z. P.; Hu, C. R.; Ross, Joseph H., Jr.

    2007-03-01

    We have presented a combined experimental and theoretical study of the effect of Gallium substitution on the superconductivity of the type I clathrate Ba8Si46-xGax. In Ga-doped clathrates, the Ga state is found to be strongly hybridized with the cage conduction-band state. Ga substitution results in a shift toward to a lower energy, a decrease of density of states at Fermi level, a lowering of the carrier concentration and a breakage of integrity of the sp3 hybridized networks. These play key roles in the suppression of superconductivity. For Ba8Si40Ga6, the onset of the superconducting transition occurs at Tc=3.3 K. The investigation of the magnetic superconducting state shows that Ba8Si40Ga6 is a type II superconductor. The critical magnetic fields were measured to be Hc1=35 Oe and Hc2=8.5 kOe. Our estimate of the lectron-phonon coupling reveals that Ba8Si40Ga6 is a moderate phonon-mediated BCS superconductor.

  9. Growth and scintillation properties of BaMgF4

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Kawaguchi, Noriaki; Fujimoto, Yutaka; Sugiyama, Makoto; Furuya, Yuki; Kamada, Kei; Yokota, Yuui; Yoshikawa, Akira; Chani, Valery

    2010-01-01

    By using the micro-pulling down (μ-PD) method, the barium magnesium fluoride (BaMgF 4 ) single crystalline scintillator was produced. The crystal was cut and mirror polished to the physical dimensions of 1x2x10 mm 3 for examination of scintillation properties. BaMgF 4 demonstrated ∼70% transmittance in wavelength range above 170 nm, and strong emission peaking around 205 nm was observed under X-ray excitation. The absolute light yield of BaMgF 4 was 1300±100 ph/MeV, and the decay time profile showed two components as 0.57±0.01 (70%) and 2.2±0.31 (30%) ns at room temperature.

  10. Improvement of β-phase crystal formation in a BaTiO3-modified PVDF membrane

    Science.gov (United States)

    Lin, SHEN; Lei, GONG; Shuhua, CHEN; Shiping, ZHAN; Cheng, ZHANG; Tao, SHAO

    2018-04-01

    In this paper, low temperature plasma is used to modify the surface of barium titanate (BaTiO3) nanoparticles in order to enhance the interfacial compatibility between ferroelectric poly(vinylidene fluoride) (PVDF) and BaTiO3 nanoparticles. The results demonstrate that oxygenic groups are successfully attached to the BaTiO3 surface, and the quantity of the functional groups increases with the treatment voltage. Furthermore, the effect of modified BaTiO3 nanoparticles on the morphology and crystal structure of the PVDF/BaTiO3 membrane is investigated. The results reveal that the dispersion of BaTiO3 nanoparticles in the PVDF matrix was greatly improved due to the modification of the BaTiO3 nanoparticles by air plasma. It is worth noting that the formation of a β-phase in a PVDF/modified BaTiO3 membrane is observably promoted, which results from the strong interaction between PVDF chains and oxygenic groups fixed on the BaTiO3 surface and the better dispersion of BaTiO3 nanoparticles in the PVDF matrix. Besides, the PVDF/modified BaTiO3 membrane at the treatment voltage of 24 kV exhibits a lower water contact angle (≈68.4°) compared with the unmodified one (≈86.7°). Meanwhile, the dielectric constant of PVDF/BaTiO3 nanocomposites increases with the increase of working voltage.

  11. BaBar Data Aquisition

    CERN Document Server

    Scott, I; Grosso, P; Hamilton, R T; Huffer, M E; O'Grady, C; Russell, J J

    1998-01-01

    The BaBar experiment at the Stanford Linear Accelerator Center is designed to perform a search for CP violation by analysing the decays of a very large sample of B and Bbar mesons produced at the high luminosity PEP-11 accelerator. The data acquisition system must cope with a sustained high event rate, while supporting real time feature extraction and data compression with minimal dead time. The BaBar data acquisition system is based around a common VME interface to the electronics read-out of the separate detector subsystems. Data from the front end electronics is read into commercial VME processors via a custom "personality card" and PCI interface. The commercial CPUs run the Tornado operating system to provide a platform for detector subsystem code to perform the necessary data processing. The data are read out via a non-blocking network switch to a farm of commercial UNIX processors. Careful design of the core data acquisition code has enabled us to sustain events rates in excess of 20 kHz while maintaini...

  12. Effect of Ba in the glass characteristics of cesium loaded iron phosphate glasses

    International Nuclear Information System (INIS)

    Joseph, Kitheri; Asuvathraman, R.; Vasudeva Rao, P.R.

    2015-01-01

    Radioactive 137 Cs extracted from high level nuclear waste, when immobilized in a suitable matrix can be used as a γsource in medical industry. Iron phosphate glass (IPG) is one of a suitable matrix for the immobilization of 137 Cs prior to the immobilization of 137 Cs in IPG, it is essential to optimize the immobilization conditions using natural (inactive) cesium. Glass characteristics of inactive Cs loaded iron phosphate glasses were already explored in our earlier studies. However, the change in glass characteristics of 137 Cs loaded iron phosphate glass to 137 Ba loaded iron phosphate glass need to be studied before the immobilization of 137 Cs in iron phosphate glass as 137 Cs transforms to 137 Ba due to nuclear transmutation ( 137 Cs(β,γ) 137 Ba). This paper reports the studies on such a behaviour by incorporating inactive Ba in cesium loaded iron phosphate glasses. Cs and Ba loaded iron phosphate glasses were prepared by melt quench technique in air using appropriate amounts of Fe 2 O 3 , NH 4 H 2 PO 4 , Ba(OH) 2.8 H 2 O and Cs 2 CO 3 . The chemicals were added such that the glass formed possesses the batch composition of (a) 21.4 wt. % Fe 2 O 3 -45 wt. % Cs 2 O-5 wt % BaO-P 2 O 5 (henceforth referred as IP50Cs45Ba5); (b) 21.4 wt. % Fe 2 O 3 -25 wt. % Cs 2 O-25 wt % BaO-P 2 O5 (henceforth referred as IP50Cs25Ba25). The thermal expansion measurements were also carried out using a home-built quartz push-rod dilatometer. The data related to change in thermal expansion behaviour, glass forming ability, glass stability and structural changes in phosphate network due to the partial replacement of Cs with Ba will also be discussed. (author)

  13. The BaBar Software Architecture and Infrastructure

    International Nuclear Information System (INIS)

    Cosmo, Gabriele

    2003-01-01

    The BaBar experiment has in place since 1995 a software release system (SRT Software Release Tools) based on CVS (Concurrent Version System) which is in common for all the software developed for the experiment, online or offline, simulation or reconstruction. A software release is a snapshot of all BaBar code (online, offline, utilities, scripts, makefiles, etc.). This set of code is tested to work together, and is indexed by a release number (e.g., 6.8.2) so a user can refer to a particular release and get reproducible results. A release will involve particular versions of packages. A package generally consists of a set of code for a particular task, together with a GNU makefile, scripts and documentation. All BaBar software is maintained in AFS (Andrew File System) directories, so the code is accessible worldwide within the Collaboration. The combination SRT, CVS, AFS, has demonstrated to be a valid, powerful and efficient way of organizing the software infrastructure of a modern HEP experiment with collaborating Institutes distributed worldwide, both in a development and production phase

  14. Structural phase transition of BaZrO3 under high pressure

    International Nuclear Information System (INIS)

    Yang, Xue; Li, Quanjun; Liu, Ran; Liu, Bo; Zhang, Huafang; Jiang, Shuqing; Zou, Bo; Cui, Tian; Liu, Bingbing; Liu, Jing

    2014-01-01

    We studied the phase transition behavior of cubic BaZrO 3 perovskite by in situ high pressure synchrotron X-ray diffraction experiments up to 46.4 GPa at room temperature. The phase transition from cubic phase to tetragonal phase was observed in BaZrO 3 for the first time, which takes place at 17.2 GPa. A bulk modulus 189 (26) GPa for cubic BaZrO 3 is derived from the pressure–volume data. Upon decompression, the high pressure phase transforms into the initial cubic phase. It is suggested that the unstable phonon mode caused by the rotation of oxygen octahedra plays a crucial role in the high pressure phase transition behavior of BaZrO 3

  15. Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.F., E-mail: wangshifa2006@yeah.net [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Science and technology on vacuum technology and physics laboratory, Lanzhou Institute of Physics, Lanzhou 730000, Gansu (China); Li, Q. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Zu, X.T., E-mail: xtzu@uestc.edu.cn [Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Xiang, X.; Liu, W. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Li, S., E-mail: sean.li@unsw.edu.au [School of Material Science and Engineering, University of New South Wales, Sydney 2052 (Australia)

    2016-12-01

    (Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M{sup 2+} ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe{sub 2}O{sub 4} magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe{sub 2}O{sub 4} of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly. - Graphical abstract: Schematic representation of the proposed model for MFe{sub 2}O{sub 4} nanoparticle synthesis, starting from EDTA-chelated M{sup 2+} (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

  16. Microstructural properties of BaTiO3 ceramics and thin films

    International Nuclear Information System (INIS)

    Fundora C, A.; Portelles, J.J.; Siqueiros, J.M.

    2000-01-01

    A microstructural study of BaTiO 3 ceramics obtained by the conventional ceramic method is presented. Targets were produced to grow BaTiO 3 thin films by pulsed laser deposition on Pt/Ti/Si (100) substrates. X-ray diffraction, Auger Electron Spectroscopy, X-ray Photon Spectroscopy and Scanning Electron Microscopy were used to study the properties of the BaTiO 3 ceramic samples and thin films, as deposited and after an annealing process. (Author)

  17. The Preparation and Characterization of Tourmaline-Containing Functional Copolymer p (VST/MMA/BA

    Directory of Open Access Journals (Sweden)

    Yingmo Hu

    2018-01-01

    Full Text Available Tourmaline was modified with vinyl triethoxysilane containing double bond to prepare the polymerizable organic vinylsiliconoxyl tourmaline (VST and then copolymerized with methyl methacrylate (MMA and butyl acrylate (BA to produce the tourmaline-containing functional copolymer p (VST/MMA/BA. The structures and morphologies of VST and p (VST/MMA/BA copolymer were characterized by IR, SEM, and EDX. The experimental results indicated that tourmaline was introduced into the copolymer via surface modification and the tourmaline-containing functional copolymer was obtained by a copolymerization process with MMA and BA. The prepared p (VST/MMA/BA copolymer displayed excellent storage stabilities, high far-infrared radiation and negative ion releasing performances, and good mechanical properties.

  18. Perovskite phases in the systems AO-SE/sub 2/O/sub 3/-UO/sub 2,x/ with A=alkaline earth metal and SE=rare earths, La, and Y. VII. The systems Ba/sub 2/CaUO/sub 6/-Ba/sub 2/Gd/sub 0. 67/UO/sub 6/ and Ba/sub 2/CaUO/sub 6/-Ba/sub 2/Y/sub 0. 67/UO/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Seemann, I; Schittenhelm, H J [Tuebingen Univ. (F.R. Germany). Institut fuer Anorganische Chemie

    1976-05-01

    The ordered perovskite Ba/sub 2/CaUO/sub 6/ forms a solid solution series with Ba/sub 2/Gdsub(0.67)UO/sub 6/ and Ba/sub 2/Ysub(0.67)UO/sub 6/, respectively. The deviations from the ideal behaviour are studied by X-ray, diffuse reflectance and vibrational methods.

  19. Perovskite phases in the systems AO-SE/sub 2/O/sub 3/-UO/sub 2,x/ with A=alkaline earth metal and SE=rare earths, La, and Y. IX. The systems Ba/sub 2/SrUO/sub 6/-Ba/sub 2/Gd/sub 0. 67/UO/sub 6/ and Ba/sub 2/SrUO/sub 6/-Ba/sub 2/Y/sub 0. 67/UO/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Seemann, I [Tuebingen Univ. (F.R. Germany). Inst. fuer Anorganische Chemie I

    1976-07-01

    The ordered perovskite Ba/sub 2/SrUO/sub 6/ forms a solid solution series with Ba/sub 2/Gdsub(0.67)UO/sub 6/ and Ba/sub 2/Ysub(0.67)UO/sub 6/ respectively. The deviations from the ideal behaviour are studied by X-ray, diffuse reflectance and vibrational methods.

  20. Benzo(A)pyrene (BaP) treatment results in complete infertility in female pigeons

    Energy Technology Data Exchange (ETDEWEB)

    Hough, J.L.; Darrow, D.; Eaton, J.; Baird, M.B. (Masonic Medical Research Lab., Utica, NY (United States))

    1991-03-11

    BaP is a carcinogenic polycyclic aromatic hydrocarbon (PAH) and a common environmental pollutant. Show Racer and White Carneau female pigeons injected weekly with BaP for 3 for 5 months were completely infertile, with ovaries appearing necrotic or oxidized. Fertility in benzo(e)pyrene (BeP, a noncarcinogenic PAH) treated birds was the same as for corn oil treated controls, as was embryo development. Thus, infertility in BaP treated birds appears to be related to its structure-carcinogenic potential. There was no readily apparent affect of BaP treatment on testes from male birds. In order to determine whether BaP metabolites covalently bind to DNA in the ovaries of these birds, pigeons were injected with BaP or BeP, controls were injected with corn oil. Animals were sacrificed 24h later, the ovaries or testes removed, and the DNA isolated and analyzed for PAH-DNA adducts by {sup 32}P-post labeling assay. One major and one minor PAH-DNA adduct was found in ovaries and testes from BaP treated birds. However, no PAH adducts were found in BeP treated or control animals. Thus, problems with fertility may arise because of the alteration in DNA by BaP metabolite binding in ovaries where rapid cell growth occurs during egg production.

  1. Isothermal cross-sections of Sr-Al-Ge and Ba-Al-Ge systems at 673 K

    International Nuclear Information System (INIS)

    Kutsenok, N.L.; Yanson, T.I.

    1987-01-01

    X-ray and microstructural analyses are used to study phase equilibria in Sr-Al-Ge and Ba-Al-Ge systems. Existence of SrAl 2 Ge 2 , Sr(Al, Ge) 2 Ba(Al, Ge) 2 , Sr 3 Al 2 Ge 2 , Ba 3 Al 2 Ge 2 ternary compounds is confirmed, a new BaGe 4 binary compound and also new ternary compounds of approximate composition Sr 57 Al 30 Ge 13 and Ba 20 Al 40 Ge 40 , which crystal structure is unknown, are detected. Aluminium solubility in SrAl 4 and BaAl 4 binary compounds (0.05 atomic fraction) is determined. Ba(Al, Ge) 2 compound homogeneity region is defined more exactly (aluminium content varies from 0.27 to 0.51 at. fractions)

  2. Water adsorption induced in-plane domain switching on BaTiO{sub 3} surface

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.; Bai, Y.; Su, Y. J., E-mail: yjsu@ustb.edu.cn [Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), University of Science and Technology Beijing, Beijing 100083 (China); Wang, B. C. [Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), University of Science and Technology Beijing, Beijing 100083 (China); Multiscale Materials Modelling group, Department of Materials and Engineering, Royal Institute of Technology, SE-10044 Stockholm (Sweden)

    2015-09-07

    In this study, the influences of the adsorption of water molecules on the changes in the atomic and electric structures of BaTiO{sub 3} surface were investigated using ab initio calculation. Water molecules are molecularly and dissociatively adsorbed on the BaTiO{sub 3} surface, which makes electrons transfer from water molecules to the BaTiO{sub 3} surface. The redistribution of electrons in the BaTiO{sub 3} surface layers weakens the Ba-O interactions and strengthens the Ti-O interactions, so that the Ti atom shifts in TiO{sub 2} plane, i.e., an in-plane domain switching. The adsorption of water molecules on BaTiO{sub 3} surfaces also results in a reduction in the surface rumpling.

  3. Advances in enlargement of melt-textured Gd-Ba-Cu-O superconductors

    International Nuclear Information System (INIS)

    Nariki, S; Sakai, N; Kita, M; Fujikura, M; Murakami, M; Hirabayashi, I

    2006-01-01

    We investigated the fabrication of melt-textured Gd-Ba-Cu-O bulk superconductors with the employment of a Gd 2 BaO 4 (Gd210)-BaCuO 2 -CuO precursor. This enabled us to synthesize a very large Gd-Ba-Cu-O bulk superconductor, 140 mm in diameter. The trapped field distribution measured at 77 K revealed that the sample had no serious cracks, and the maximum field was 2.3 T. The formation behaviour and depressing mechanism of cracking were studied using sintered Gd210-containing precursors. The Ba-Cu-O component in the precursor melted at around 900 deg. C. The formation of such a liquid phase enhanced the densification of the precursor by liquid phase sintering. The mechanical strength of the sintered precursor was increased compared to the conventional Gd123-Gd211 precursor. This will be effective in preventing crack formation in the texturing process of large single-grain samples. The superconducting properties of the bulk sample fabricated from Gd210-containing precursor have been discussed

  4. Rattling of Ba-atoms in Ba8ZnxGe43-5x/8([]3-3x/8)

    International Nuclear Information System (INIS)

    Melnychenko, N.; Grytsiv, A.; Rotter, M.; Rogl, P.; Devishvili, A.

    2006-01-01

    Full text: In order to improve the figure of merit of thermoelectric materials, one of the key parameters to be minimized is the lattice thermal conductivity. It is thus essential for the design of new thermoelectric materials to understand the lattice dynamics, especially the scattering mechanism of low energy phonons. The present paper describes formation, phase relations at subsolidus temperatures as well as at 800 o C, crystal chemistry and physical properties of a series of ternary clathrates as part of the solid solution, Ba 8 Zn x (Ge 43-5x/8[]3-3x/8 ), deriving from binary Ba 8 Ge 43 []3 with a solubility limit of 8 Zn per formula unit at 800 o C. Structural investigations in all cases confirm cubic primitive symmetry with a lattice parameter a ∼ 1.1 nm consistent with the space group type Pm-3n. Studies of transport coefficients evidence electrons as the majority charge carriers in the systems. Thermal conductivity exhibits a pronounced low temperature maximum, dominated by the lattice contribution, while at higher temperatures the electronic part gains weight. Inelastic neutron scattering experiments are used to study the phonon spectrum for Ba 8 Zn 8 Ge 38 . (author)

  5. Carbon-14 immobilization via the CO2-Ba(OH)2 hydrate gas-solid reaction

    International Nuclear Information System (INIS)

    Haag, G.L.

    1981-08-01

    For the treatment of an air-based off-gas stream, the use of packed beds of Ba(OH) 2 .8H 2 O flakes to remove CO 2 has been demonstrated. However, the operating conditions must be maintained between certain upper and lower limits with respect to the partial pressure of water. If the water vapor pressure in the gas is less than the dissociation vapor pressure of Ba(OH) 2 .8H 2 O, the bed will deactivate. If the vapor pressure is considerably greater, pressure drop problems will increase with increaseing humidity as the particles curl and degrade. Results have indicted that when operated in the proper regime, the bulk of the increase in pressure drop results from the conversion of Ba(OH) 2 .8H 2 O to BaCO 3 and not from the hydration of the commercial Ba(OH) 2 .8H 2 O (i.e., Ba(OH) 2 .7.50H 2 O) to Ba(OH) 2 .8H 2 O

  6. The BaBar electromagnetic calorimeter

    CERN Document Server

    Lewandowski, B

    2002-01-01

    The BaBar electromagnetic calorimeter is a hermetic, total-absorption array of CsI(Tl)-crystals, operated at the asymmetric e sup - e sup + -collider PEP-II at SLAC. The design and the status of the performance as of February 2002 is presented.

  7. Phase formation, structural and microstructural characterization of novel oxynitride-perovskites synthesized by thermal ammonolysis of (Ca,Ba)MoO4 and (Ca,Ba)MoO3

    International Nuclear Information System (INIS)

    Logvinovich, D.; Aguirre, M.H.; Hejtmanek, J.; Aguiar, R.; Ebbinghaus, S.G.; Reller, A.; Weidenkaff, A.

    2008-01-01

    Reactions of AMoO 4 and AMoO 3 (A=Ca 2+ , Ba 2+ ) with ammonia were investigated at 873 K 3 and to study their crystal structure. CaMo(O,N) 3 and BaMo(O,N) 3 were prepared by thermal ammonolysis of the corresponding CaMoO 3 and BaMoO 3 precursors at T=898 and 998 K, respectively. The structural parameters of the oxynitrides were obtained from Rietveld refinements of X-ray and neutron powder diffraction data. CaMo(O,N) 3 crystallizes in the GdFeO 3 distorted perovskite structure with orthorhombic space group Pbnm and a=5.5029(1) A, b=5.5546(1) A, c=7.8248(1) A as determined by X-ray powder diffraction. Its O/N content refined from the neutron diffraction data corresponds to the composition CaMoO 1.7(1) N 1.3(1) . BaMo(O,N) 3 crystallizes in the cubic perovskite structure with space group Pm3-bar m and a=4.0657(1) A as determined by X-ray powder diffraction. Transmission electron microscopy reveals a complex microstructure for both CaMoO 3 and CaMoO 1.7(1) N 1.3(1) represented by twin domains of different orientation. - Graphical abstract: Reactions of AMoO 4 and AMoO 3 (A=Ca 2+ , Ba 2+ ) oxides with ammonia have been studied at T=873-1123 K. Orthorhombic CaMoO 1.7(1) N 1.3(1) (Pbnm) and cubic BaMo(O,N) 3 (Pm3-bar m) were prepared by thermal ammonolysis of the corresponding CaMoO 3 and BaMoO 3 precursors at T=898 and 998 K, respectively. Display Omitted

  8. Evolution of deformation in neutron-rich Ba isotopes up to A =150

    Science.gov (United States)

    Licǎ, R.; Benzoni, G.; Rodríguez, T. R.; Borge, M. J. G.; Fraile, L. M.; Mach, H.; Morales, A. I.; Madurga, M.; Sotty, C. O.; Vedia, V.; De Witte, H.; Benito, J.; Bernard, R. N.; Berry, T.; Bracco, A.; Camera, F.; Ceruti, S.; Charviakova, V.; Cieplicka-Oryńczak, N.; Costache, C.; Crespi, F. C. L.; Creswell, J.; Fernandez-Martínez, G.; Fynbo, H.; Greenlees, P. T.; Homm, I.; Huyse, M.; Jolie, J.; Karayonchev, V.; Köster, U.; Konki, J.; Kröll, T.; Kurcewicz, J.; Kurtukian-Nieto, T.; Lazarus, I.; Lund, M. V.; Mǎrginean, N.; Mǎrginean, R.; Mihai, C.; Mihai, R. E.; Negret, A.; Orduz, A.; Patyk, Z.; Pascu, S.; Pucknell, V.; Rahkila, P.; Rapisarda, E.; Regis, J. M.; Robledo, L. M.; Rotaru, F.; Saed-Samii, N.; Sánchez-Tembleque, V.; Stanoiu, M.; Tengblad, O.; Thuerauf, M.; Turturica, A.; Van Duppen, P.; Warr, N.; IDS Collaboration

    2018-02-01

    The occurrence of octupolar shapes in the Ba isotopic chain was recently established experimentally up to N =90 . To further extend the systematics, the evolution of shapes in the most neutron-rich members of the Z =56 isotopic chain accessible at present, Ba,150148, has been studied via β decay at the ISOLDE Decay Station. This paper reports on the first measurement of the positive- and negative-parity low-spin excited states of 150Ba and presents an extension of the β -decay scheme of 148Cs. Employing the fast timing technique, half-lives for the 21+ level in both nuclei have been determined, resulting in T1 /2=1.51 (1 ) ns for 148Ba and T1 /2=3.4 (2 ) ns for 150Ba. The systematics of low-spin states, together with the experimental determination of the B (E 2 :2+→0+) transition probabilities, indicate an increasing collectivity in Ba-150148, towards prolate deformed shapes. The experimental data are compared to symmetry conserving configuration mixing (SCCM) calculations, confirming an evolution of increasingly quadrupole deformed shapes with a definite octupolar character.

  9. Stability of Tl-Ba-Ca-Cu-O superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Siegal, M. P. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Overmyer, D. L. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Venturini, E. L. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Padilla, R. R. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Provencio, P. N. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States)

    1999-12-01

    We report the stability of TlBa{sub 2}CaCu{sub 2}O{sub 7} and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} on LaAlO{sub 3}(100) epitaxial thin films, under a variety of conditions. All films are stable in acetone and methanol and with repeated thermal cycling to cryogenic temperatures. Moisture, especially vapor, degrades film quality rapidly. These materials are stable to high temperatures in either N{sub 2} or O{sub 2} ambients. While total degradation, resulting from Tl depletion, occurs at the same temperatures for both phases, 600 degree sign C in N{sub 2} and 700 degree sign C in O{sub 2}, the onset of degradation occurs at somewhat lower temperatures for TlBa{sub 2}CaCu{sub 2}O{sub 7} than for Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8}. (c) 1999 Materials Research Society.

  10. Surface structures and dielectric response of ultrafine BaTiO3 particles

    International Nuclear Information System (INIS)

    Jiang, B.; Peng, J.L.; Bursill, L.A.

    1998-01-01

    Characteristic differences are observed for the dielectric response and microstructures of BaTiO 3 nanoscale fine powders prepared using sol gel (SG) and steric acid gel (SAG) methods. The former exhibit a critical size below which there is no paraelectric/ferroelectric phase transition whereas BaTiO 3 prepared via the SAG route remained cubic for all conditions. Atomic resolution images of both varieties showed a high density of interesting surface steps and facets. Computer simulated images of surface structure models showed that the outer (100) surface was typically a BaO layer and that at corners and ledges the steps are typically finished with Ba+2 ions; i.e. the surfaces and steps are Ba-rich. Otherwise the surfaces were typically clean and free of amorphous layers. The relationship between the observed surfaces structures and theoretical models for size effects on the dielectric properties is discussed. (authors)

  11. Identification of the neutron-rich nuclides /sup 147; 148/Ba and half- life determination of the heavy isotopes of Rb, Sr, Y, Cs, Ba and La

    CERN Document Server

    Amiel, S; Nir-El, Y; Shmid, M

    1976-01-01

    The neutron nuclides /sup 147; 148/Ba were produced in the thermal neutron induced fission of /sup 235/U. A new surface ionization integrated target ion source operating at temperatures in the region of 1800 degrees C permits the measurement of half-lives of isotopes down to about 0.1 sec due to the very fast release of atoms from the target. Isotopes of Rb, Sr, Cs, and Ba were separated by positive surface ionization and their half-lives measured using beta activity detected by a silicon surface barrier detector with a depletion depth of 300 mu . The isotopes /sup 147/Ba and /sup 148/Ba were identified for the first time and their half-lives were found to be 0.72+or-0.07 sec and 0.47+or-0.20 sec, respectively. (0 refs).

  12. Bifunctional properties of hydrothermal synthesized BaMF4 (M = Co, Ni and Zn

    Directory of Open Access Journals (Sweden)

    Farheen N. Sayed

    2013-07-01

    Full Text Available BaMF4 (M = Co, Ni and Zn samples having orthorhombic structure have been synthesized by a mild hydrothermal method and characterized by x-ray diffraction (XRD, magnetic and electrical measurements. Single phase formation of these compounds has been found to be dependent on various factors like reaction time, pH, temperature etc. All the samples showed ferroelectricity, which decreases with increase in temperature. BaMF4 (M = Co, Ni samples show 10-15 times more leakage current compared to that of BaZnF4 at higher applied field. Absence of multivalent ions in BaZnF4 can be the reason for its minimum leakage current. All the samples except, BaZnF4, exhibit weak room temperature ferromagnetism also.

  13. Estimation of the specific mass effect in the isotope shifts of energy levels in the optical spectrum of Ba I and Ba II

    International Nuclear Information System (INIS)

    Pendrill, L.R.

    1984-01-01

    A graphical method for separating mass and volume effects from purely optical isotope shift data is presented and compared with King's ''bunching'' method. Recent experimental data on isotope shifts for a wide range of spectral lines in the naturally abundant isotopes of Ba I and Ba II are analysed. Some agreement is found with muonic X-ray data concerning the nuclear size for the isotopes 136, 137 and 138, but there is disagreement (over 20%) for the other isotopes. The level isotope shifts are further parameterised in terms of a linear model, and the specific mass effect is decomposed into sums of one-electron and two-electron shift parameters with respect to the inert-gas like ground state of Ba III. (orig.)

  14. Intertextuality in Ba's So Long a Letter and Umunnakwe's Dear ...

    African Journals Online (AJOL)

    Intertextuality takes for granted the interdependence of literary texts because every artistic creation is a re-echoing of past knowledge. Mariama Ba's So Long A Letter and Ndubisi Umunnakwe's Dear Ramatoulaye are African examples. This work examines how Ba's So Long A Letter intertextualises with Umunnakwe's Dear ...

  15. A Dubious Distinction? The BA versus the BS in Psychology

    Science.gov (United States)

    Pfund, Rory A.; Norcross, John C.; Hailstorks, Robin; Aiken, Leona S.; Stamm, Karen E.; Christidis, Peggy

    2016-01-01

    Previous studies have documented small differences between the bachelor of arts (BA) and the bachelor of science (BS) psychology degrees in their general education core requirements, particularly mathematics and science courses. But are there differences between the BA and BS degrees within the psychology curriculum? Using data from the…

  16. modified BiFeO3–BaTiO3

    Indian Academy of Sciences (India)

    based perovskite structures lead- free BiFeO3–BaTiO3 solid solutions are popularly studied due to the high Curie temperature (TC). It was reported that the BiFeO3–BaTiO3 system possessed high piezoelectric. ∗. Author for correspondence ...

  17. CeF3(Ba) radiation hard scintillator for electromagnetic calorimeters

    International Nuclear Information System (INIS)

    Aseev, A.A.; Devitsin, E.G.; Kozlov, V.A.; Hovepyan, Yu.I.; Potashov, S.Yu.; Sokolovsky, K.A.; Uvarova, T.V.; Vasilchenko, V.G.

    1992-01-01

    The influence of divalent fluoride dopants BaF 2 , CaF 2 , SrF 2 on radiation and luminescent properties of CeF 3 crystal is studied. A high radiation hardness (>10 8 rad) has been obtained for CeF 3 crystals doped with BaF 2 . (orig.)

  18. Electrodeposition of BaCO3 coatings on stainless steel substrates ...

    Indian Academy of Sciences (India)

    Administrator

    Dedicated to the memory of the late Professor S K Rangarajan. *For correspondence. Electrodeposition of BaCO3 coatings on stainless steel substrates: Oriented growth ... orientation by an interfacial molecular recognition mechanism. BaCO3 has important applications in paint, ceramic, and paper industries. Also it is used ...

  19. Beyond survival: fostering growth and innovation in doctoral study--a concept analysis of the Ba space.

    Science.gov (United States)

    Krahe, J A E; Lalley, Cathy; Solomons, Nan M

    2014-01-25

    This concept analysis examines the Ba space in the context of interdisciplinary doctoral study in nursing and healthcare innovation in a minimal residency program. The authors identified Ba in their small, highly diverse, self-selected doctoral study group and believe Ba is an educational innovation that will prove useful to nursing and healthcare educators. Ba originates from Japanese philosophy and is foundational to the birth and sustainment of environments fostering knowledge creation. Ba manifests in complex environments where participants are emotionally invested and relies on the tacit knowledge of each participant, allowing for synthesis of rationality and intuition. Walker and Avant's concept analysis methodology will explore Ba's centrality to interdisciplinary education. Ba's utility and application in fostering innovation in doctoral study will be illustrated. Ba is a true educational innovation, enriching learning environments promoting interdisciplinary collaboration. Ba permits each member a voice and fosters a safe environment where relationships are created and sustained.

  20. Superconductivity in gallium-substituted Ba8Si46 clathrates

    Science.gov (United States)

    Li, Yang; Zhang, Ruihong; Liu, Yang; Chen, Ning; Luo, Z. P.; Ma, Xingqiao; Cao, Guohui; Feng, Z. S.; Hu, Chia-Ren; Ross, Joseph H., Jr.

    2007-02-01

    We report a joint experimental and theoretical investigation of superconductivity in Ga-substituted type-I silicon clathrates. We prepared samples of the general formula Ba8Si46-xGax , with different values of x . We show that Ba8Si40Ga6 is a bulk superconductor, with an onset at TC≈3.3K . For x=10 and higher, no superconductivity was observed down to T=1.8K . This represents a strong suppression of superconductivity with increasing Ga content, compared to Ba8Si46 with TC≈8K . Suppression of superconductivity can be attributed primarily to a decrease in the density of states at the Fermi level, caused by a reduced integrity of the sp3 -hybridized networks as well as the lowering of carrier concentration. These results are corroborated by first-principles calculations, which show that Ga substitution results in a large decrease of the electronic density of states at the Fermi level, which explains the decreased superconducting critical temperature within the BCS framework. To further characterize the superconducting state, we carried out magnetic measurements showing Ba8Si40Ga6 to be a type-II superconductor. The critical magnetic fields were measured to be HC1≈35Oe and HC2≈8.5kOe . We deduce the London penetration depth λ≈3700Å and the coherence length ξc≈200Å . Our estimate of the electron-phonon coupling reveals that Ba8Si40Ga6 is a moderate phonon-mediated BCS superconductor.

  1. BaMa / Raivo Juurak

    Index Scriptorium Estoniae

    Juurak, Raivo, 1949-

    2002-01-01

    Eesti ülikoolide üleminekust 3+2 süsteemile. Lühend BaMa on tulnud kasutusele seoses Euroopa ülikoolide õppekavade reformimisega ning tähistab õppekava, kus esimese astme läbimise järel omandatakse bakalaureuse- ja teise järel magistrikraad. Õppekavade tüüpidest Eesti ja Euroopa Liidu kõrgkoolides ning Bologna deklaratsioonist

  2. Hexagonal perovskites with cationic vacancies. 21. Structure of Ba/sub 4/Nb/sub 2/WvacantO/sub 12/ and Ba/sub 3/LaNb/sub 3/vacantO/sub 12/

    Energy Technology Data Exchange (ETDEWEB)

    Rother, H J; Kemmler-Sack, S; Treiber, U; Cyris, W R [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-07-01

    Compounds of type Ba/sub 4/M/sub 2/sup(V)WvacantO/sub 12/ and Ba/sub 3/LaM/sub 3/sup(V)vacantO/sub 12/ with Msup(V) = Nb, Ta belong to the group of rhombohedral 12 L stacking polytypes (space group R-3m, sequence (hhcc)/sub 3/). The structure determinations on powder patterns for the Nb compounds gave a refined, intensity related R' value of 6.3% (Ba/sub 4/Nb/sub 2/WvacantO/sub 12/) and 6.6% (Ba/sub 3/LaNb/sub 3/vacantO/sub 12/). The octahedral net consists of blocks of three face connected octahedra with a central void (M/sub 2/vacantO/sub 12/ unit), which are linked to each other through single corner sharing octahedra. In both compounds the M atoms in the M/sub 2/vacantO/sub 12/ groups are displaced in the direction of the central void. The A atoms move in the same direction but the dislocation for A in the hexagonal packed sheets (neighbouring the vacancies) is stronger than in the cubic packed AO/sub 3/ sheets. The results of the vibrational spectroscopic investigations are reported for Ba/sub 4/Nb/sub 2/WvacantO/sub 12/, Ba/sub 4/Ta/sub 2/WvacantO/sub 12/, Ba/sub 3/LaNb/sub 3/vacantO/sub 12/ and Ba/sub 4/CeW/sub 2/vacantO/sub 12/; they are discussed in connection with the factor group analysis.

  3. Adsorption removal of Sr by Barium impregnated 4A Zeolite(BaA) from high radioactive seawater waste

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eil Hee; Lee, Keun Young; Kim, Kwang Wook; Kim, Ik Soo; Chung, Dong Yong; Moon, Jei Kwon; Choi, Jong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-06-15

    This study investigated the removal of Sr, which was one of the high radioactive nuclides, by adsorption with Barium (Ba) impregnated 4A zeolite (BaA) from high-radioactive seawater waste (HSW). Adsorption of Sr by BaA (BaA-Sr), in the impregnated Ba concentration of above 20.2wt%, was decreased by increasing the impregnated Ba concentration, and the impregnated Ba concentration was suitable at 20.2wt%. The BaA-Sr adsorption was added to the co-precipitation of Sr with BaSO4 precipitation in the adsorption of Sr by 4A (4A-Sr) within BaA. Thus, it was possible to remove Sr more than 99% at m/V (adsorbent weight/solution volume)=5 g/L for BaA and m/V >20 g/L for 4A, respectively, in the Sr concentration of less than 0.2 mg/L (actual concentration level of Sr in HSW). It shows that BaA-Sr adsorption is better than 4A-Sr adsorption in for the removal capacity of Sr per unit gram of adsorbent, and the reduction of the secondary solid waste generation (spent adsorbent etc.). Also, BaA-Sr adsorption was more excellent removal capacity of Sr in the seawater waste than distilled water. Therefore, it seems to be effective for the direct removal of Sr from HSW. On the other hand, the adsorption of Cs by BaA (BaA-Cs) was mainly performed by 4A within BaA. Accordingly, it seems to be little effect of impregnated Ba into BaA. Meanwhile, BaA-Sr adsorption kinetics could be expressed the pseudosecond order rate equation. By increasing the initial Sr concentrations and the ratios of V/m, the adsorption rate constants (k2) were decreased, but the equilibrium adsorption capacities (qe) were increasing. However, with increasing the temperature of solution, k2 was conversely increased, and qe was decreased. The activation energy of BaA-Sr adsorption was 38 kJ/mol. Thus, the chemical adsorption seems to be dominant rather than physical adsorption, although it is not a chemisorption with strong bonding form.

  4. Stellar neutron capture cross sections of the Ba isotopes

    International Nuclear Information System (INIS)

    Voss, F.; Wisshak, K.; Guber, K.; Kaeppeler, F.; Reffo, G.

    1994-03-01

    The neutron capture cross sections of 134 Ba, 135 Ba, 136 Ba, and 137 Ba were measured in the energy range from 5 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7 Li(p,n) 7 Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4π Barium Fluoride Detector. Several runs have been performed under different experimental conditions to study the systematic uncertainties, which resulted mainly from the large ratios of total to capture cross sections of up to 400. The cross section ratios were determined with an overall uncertainty of ∼3%, an improvement by factors of five to eight compared to existing data. Severe discrepancies were found with respect to previous results. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=10 keV and 100 keV. These stellar cross sections were used in an s-process analysis. For the s-only isotopes 134 Ba and 136 Ba the N s ratio was determined to 0.875±0.025. Hence, a significant branching of the s-process path at 134 Cs can be claimed for the first time, in contrast to predictions from the classical approach. This branching yields information on the s-process temperature, indicating values around T 8 =2. The new cross sections are also important for the interpretation of barium isotopic anomalies, which were recently discovered in SiC grains of carbonaceous chondrite meteorites. Together with the results from previous experiments on tellurium and samarium, a general improvement of the N s systematics in the mass range A=120 to 150 is achieved. This allows for a more reliable separation of s- and r-process yields, resulting in an improved assignment of the respective contributions to elemental barium that is required for comparison with stellar observations. (orig.) [de

  5. BaFCl:Eu2+, a new phosphor for X-ray-intensifying screens

    International Nuclear Information System (INIS)

    Stevels, A.L.N.; Pingault, F.

    1975-01-01

    A number of phosphors for X-ray-intensifying screens have been evaluated by calculating figures of merit. On use in combination with standard (''blue''-sensitive) X-ray film, BaFCl:Eu 2+ and BaFBr:Eu 2+ give better performance than the traditional CaWO 4 and more recently developed UV or blue-emitting materials (e.g., sulphates and y-oxysulphides). The calculated figures of merit of BaFCl:Eu 2+ or BaFBr:Eu 2+ /standard-film combinations are comparable to those of Gd 2 O 2 S:Tb/green-sensitive X-ray film systems. The preparation of optimal fluorohalide:Eu 2+ phosphors involves proper formation of the host lattice, complete reduction of Eu 3+ ions as well as elimination of afterglow. Measurements on powders and experimental screens indicate that by using BaFCl:Eu 2+ screens in radiography, important dose reductions can be achieved without the necessity of using other than standard (''blue''-sensitive) X-ray films

  6. Rapid preparation of ultrafine BaSO{sub 3} by SO{sub 2} storage material

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fei; Sha, Feng; Qiao, Xian Shu; Zhao, Tian Xiang; Guo, Bo; Zhang, Jian Bin [College of Chemical Engineering, Inner Mongolia University of Technology, Huhhot (Korea, Republic of)

    2017-01-15

    In this work, a green and efficient process was developed for the preparation of ultrafine BaSO{sub 3} with layered nanostructure surface via the reaction of BaCl{sub 2} with a SO{sub 2} storage material (SO{sub 2}SM) at room temperature. The absorption of SO{sub 2} with equimolar ethylenediamine (EDA) and ethylene glycol (EG) afforded SO{sub 2}SM, which not only offered alkyl sulfite but also released EDA and EG that served as efficient surfactants to promote the formation of BaSO{sub 3} with spherical morphology and porous structure in the process of synthesis of ultrafine BaSO{sub 3}. The factors affecting the morphology and size of BaSO{sub 3} particle were assessed by investigating the effects of SO{sub 2}SM concentration, BaCl{sub 2} concentration, stirring time and speed. It was found that a higher SO{sub 2}SM concentration led to a higher degree of supersaturation, and the particle size of BaSO{sub 3} could be reduced by increasing SO{sub 2}SM concentration. Moreover, under the identified optimal reaction conditions, ultrafine BaSO{sub 3} was obtained with an average diameter of 450 nm. In addition, a plausible formation process of BaSO{sub 3} was proposed to explain the observed reaction results. Overall, the developed process in this work provides an efficient method for the capture, utilization, and conversion of SO{sub 2} into a valuable chemical.

  7. Synthesis of BaTiO3 powder from barium titanyl oxalate (BTO ...

    Indian Academy of Sciences (India)

    Unknown

    the synthesis of BaTiO3 from the mixture of barium car- bonate and titanium dioxide employing microwave heat- ing. They observed that hypostoichiometric TiO2 (TiO2–x) reacted with BaCO3 in the presence of microwave field at temperature as low as 350°C to give the mixture of hexa- gonal and tetragonal forms of BaTiO3 ...

  8. Self-Organized Ni Nanocrystal Embedded in BaTiO3 Epitaxial Film

    Directory of Open Access Journals (Sweden)

    Ge FF

    2010-01-01

    Full Text Available Abstract Ni nanocrystals (NCs were embedded in BaTiO3 epitaxial films using the laser molecular beam epitaxy. The processes involving the self-organization of Ni NCs and the epitaxial growth of BaTiO3 were discussed. With the in situ monitoring of reflection high-energy electron diffraction, the nanocomposite films were engineered controllably by the fine alternation of the self-organization of Ni NCs and the epitaxial growth of BaTiO3. The transmission electron microscopy and the X-ray diffraction characterization confirmed that the composite film consists of the Ni NCs layers alternating with the (001/(100-oriented epitaxial BaTiO3 separation layers.

  9. submitter Performance simulation of BaBar DIRC bar boxes in TORCH

    CERN Document Server

    Föhl, K; Castillo García, L; Cussans, D; Forty, R; Frei, C; Gao, R; Gys, T; Harnew, N; Piedigrossi, D; Rademacker, J; Ros García, A; van Dijk, M

    2017-01-01

    TORCH is a large-area precision time-of-flight detector based on the DIRC principle. The DIRC bar boxes of the BaBar experiment at SLAC could possibly be reused to form a part of the TORCH detector time-of-flight wall area, proposed to provide positive particle identification of low momentum kaons in the LHCb experiment at CERN. For a potential integration of BaBar bar boxes into TORCH, new imaging readout optics are required. From the several designs of readout optics that have been considered, two are used in this paper to study the effect of BaBar bar optical imperfections on the detector reconstruction performance. The kaon-pion separation powers obtained from analysing simulated photon hit patterns show the performance reduction for a BaBar bar of non-square geometry compared to a perfectly rectangular cross section.

  10. Melatonin ve Bağışıklık Sistemi

    OpenAIRE

    ÇETİN, E.

    2005-01-01

    Melatonin, pineal bezin beta adrenerjik reseptörlerinin aktivasyonu ile triptofandan sentezlenen bir hormondur.Üretim ve salınımı karanlık ile başlar ve aydınlıkla sona erer. Melatonin, birçok biyolojik fonksiyonun düzenlenmesinderol oynar. Bu derlemede melatonin hakkında genel bilgiler verilerek, melatoninin lenfoid dokular, humoral bağışıklık,hücresel bağışıklık ve kanser üzerine etkileri tartışılmıştır

  11. Phase equilibria, crystal chemistry, electronic structure and physical properties of Ag-Ba-Ge clathrates

    Energy Technology Data Exchange (ETDEWEB)

    Zeiringer, I.; Chen Mingxing [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Bednar, I.; Royanian, E.; Bauer, E. [Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Wien (Austria); Podloucky, R.; Grytsiv, A. [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Rogl, P., E-mail: peter.franz.rogl@univie.ac.at [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Effenberger, H. [Institute of Mineralogy and Crystallography, University of Vienna, A-1090 Wien (Austria)

    2011-04-15

    In the Ag-Ba-Ge system the clathrate type-{Iota} solid solution, Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y}, extends at 800 deg. C from binary Ba{sub 8}Ge{sub 43{open_square}3} ({open_square} is a vacancy) to Ba{sub 8}Ag{sub 5.3}Ge{sub 40.7}. For the clathrate phase (1 {<=} x {<=} 5.3) the cubic space group Pm3-bar n was established by X-ray powder diffraction and confirmed by X-ray single-crystal analyses of the samples Ba{sub 8}Ag{sub 2.3}Ge{sub 41.9{open_square}1.8} and Ba{sub 8}Ag{sub 4.4}Ge{sub 41.3{open_square}0.3}. Increasing the concentration of Ag causes the lattice parameters of the solid solution to increase linearly from a value of a = 1.0656 (x = 0, y = 3) to a = 1.0842 (x = 4.8, y = 0) nm. Site preference determination using X-ray refinement reveals that Ag atoms preferentially occupy the 6d site randomly mixed with Ge and vacancies, which become filled in the compound Ba{sub 8}Ag{sub 4.8}Ge{sub 41.2} when the Ag content increases. At 600 {sup o}C the phase region of the clathrate solution Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} becomes separated from the Ba-Ge boundary and extends from 6.6 to 9.8 at.% Ag. The compound Ba{sub 6}Ge{sub 25} (clathrate type-{Iota}X) dissolves at 800 {sup o}C a maximum of 1.5 at.% Ag. The homogeneity regions of the two ternary compounds BaAg{sub 2-x}Ge{sub 2+x} (ThCr{sub 2}Si{sub 2}-type, 0.2 {<=} x {<=} 0.7) and Ba(Ag{sub 1-x}Ge{sub x}){sub 2} (AlB{sub 2}-type, 0.65 {<=} x {<=} 0.75) were established at 800 deg. C. Studies of transport properties for the series of Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} compounds evidenced that electrons are the predominant charge carriers with the Fermi energy close to a gap. Its position can be fine-tuned by the substitution of Ge by Ag atoms and by mechanical processing of the starting material, Ba{sub 8}Ge{sub 43}. The proximity of the electronic structure at Fermi energy of Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} to a gap is also corroborated by density

  12. BaCO3 mediated modifications in structural and magnetic properties of natural nanoferrites

    Science.gov (United States)

    Widanarto, W.; Jandra, M.; Ghoshal, S. K.; Effendi, M.; Cahyanto, W. T.

    2015-04-01

    Preparing M-type barium hexaferrite and improving the magnetic response of natural ferrites by incorporating barium carbonate (BaCO3) is ever-demanding. Series of barium carbonate doped ferrites with composition (100-x)Fe3O4·xBaCO3 (x=0, 10, 20, 30 wt%) are prepared through solid state reaction method and sintered gradually at temperatures of 800 and 1000 °C. Nanoparticles of natural ferrite and commercial BaCO3 are used as raw materials. Impacts of BaCO3 on structural and magnetic properties of these synthesized ferrites are inspected. The obtained ferrites are characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) at room temperature. Uniform barium hexaferrite particles in terms of both morphology and size are not achieved. The average crystallite size of BaFe12O19 is observed to be within 30-600 nm. The sintering process results phase transformation from Fe3O4 (magnetite) to α-Fe2O3 (hematite) and the formation of hexagonal barium ferrite crystals. The occurrence of barium crystal is found to enhance with the increase of BaCO3 concentrations up to 20 wt% and suddenly drop at 30 wt%. Saturation and remanent magnetization of the doped ferrites are significantly augmented up to 16.37 and 8.92 emu g-1, respectively compared to their pure counterpart. Furthermore, the coercivity field is slightly decreased as BaCO3 concentrations are increased. BaCO3 mediated improvements in the magnetic response of natural ferrites are demonstrated.

  13. Topological phases in Ba-Borate glasses

    Science.gov (United States)

    Holbrook, Chad; Czaja, Andrew; Boolchand, Punit

    2015-03-01

    Twelve compositions in the (BaO)x(B2O3)100-x pseudo binary, in the 15% Modulated- DSC and Raman scattering experiments were undertaken systematically as function of BaO content (x). Calorimetric measurements reveal Tg(x) to show a broad maximum and the non-reversing enthalpy to show a Gaussian-like reversibility window2, both centered near x = 28%. Raman scattering displays rich lineshapes with modes similar to those observed in Na-Borates2. Modes near 808 cm-1, 770 cm-1, 740 cm-1 and 705 cm-1 are observed, and identified with breathing modes of pure and mixed rings from characteristic structural groupings2. These preliminary results suggest that glasses at x 30% in the flexible phase. Supported by NSF Grant DMR 08-53957.

  14. BaSi2 formation mechanism in thermally evaporated films and its application to reducing oxygen impurity concentration

    Science.gov (United States)

    Hara, Kosuke O.; Yamamoto, Chiaya; Yamanaka, Junji; Arimoto, Keisuke; Nakagawa, Kiyokazu; Usami, Noritaka

    2018-04-01

    Thermal evaporation is a simple and rapid method to fabricate semiconducting BaSi2 films. In this study, to elucidate the BaSi2 formation mechanism, the microstructure of a BaSi2 epitaxial film fabricated by thermal evaporation has been investigated by transmission electron microscopy. The BaSi2 film is found to consist of three layers with different microstructural characteristics, which is well explained by assuming two stages of film deposition. In the first stage, BaSi2 forms through the diffusion of Ba atoms from the deposited Ba-rich film to the Si substrate while in the second stage, the mutual diffusion of Ba and Si atoms in the film leads to BaSi2 formation. On the basis of the BaSi2 formation mechanism, two issues are addressed. One is the as-yet unclarified reason for epitaxial growth. It is found important to quickly form BaSi2 in the first stage for the epitaxial growth of upper layers. The other issue is the high oxygen concentration in BaSi2 films around the BaSi2-Si interface. Two routes of oxygen incorporation, i.e., oxidation of the Si substrate surface and initially deposited Ba-rich layer by the residual gas, are identified. On the basis of this knowledge, oxygen concentration is decreased by reducing the holding time of the substrate at high temperatures and by premelting of the source. In addition, X-ray diffraction results show that the decrease in oxygen concentration can lead to an increased proportion of a-axis-oriented grains.

  15. Concentrations of Se, Ba, Zn and Mn in Brazil nuts

    Energy Technology Data Exchange (ETDEWEB)

    Armelin, Maria José A.; Maihara, Vera A.; Cardoso, Paulo S.; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Cozollino, Silvia M.F., E-mail: marmelin@ipen.br, E-mail: vmaihara@ipen.br, E-mail: msaiki@ipen.br, E-mail: pscsilva@ipen.br, E-mail: smfcozzo@usp.br [Universidade de São Paulo (USP), SP (Brazil). Faculdade de Ciências Farmacêuticas

    2017-07-01

    The concentrations of Se, Ba, Zn and Mn were determined in samples of Brazil nuts collected in two ways: a) in a production farm predominantly for export and, b) in various points of sale from different regions of Brazil. Instrumental neutron activation analysis was the analytical technique used in this study. Results indicate that the concentrations of Se and Ba varied greatly among the Brazil nut samples analyzed. This large variability may be related to the soil characteristics from which the nuts were produced. An inverse correlation was observed between the concentrations of Se and Ba. On the other hand, the concentrations of Zn and Mn did not show significant differences among these samples. (author)

  16. Concentrations of Se, Ba, Zn and Mn in Brazil nuts

    International Nuclear Information System (INIS)

    Armelin, Maria José A.; Maihara, Vera A.; Cardoso, Paulo S.; Saiki, Mitiko; Cozollino, Silvia M.F.

    2017-01-01

    The concentrations of Se, Ba, Zn and Mn were determined in samples of Brazil nuts collected in two ways: a) in a production farm predominantly for export and, b) in various points of sale from different regions of Brazil. Instrumental neutron activation analysis was the analytical technique used in this study. Results indicate that the concentrations of Se and Ba varied greatly among the Brazil nut samples analyzed. This large variability may be related to the soil characteristics from which the nuts were produced. An inverse correlation was observed between the concentrations of Se and Ba. On the other hand, the concentrations of Zn and Mn did not show significant differences among these samples. (author)

  17. Growth and scintillation properties of BaMgF{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Yanagida, Takayuki, E-mail: t_yanagi@tagen.tohoku.ac.j [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kawaguchi, Noriaki [Tokuyama Corporation, Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); Fujimoto, Yutaka; Sugiyama, Makoto; Furuya, Yuki; Kamada, Kei; Yokota, Yuui [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Chani, Valery [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2010-09-21

    By using the micro-pulling down ({mu}-PD) method, the barium magnesium fluoride (BaMgF{sub 4}) single crystalline scintillator was produced. The crystal was cut and mirror polished to the physical dimensions of 1x2x10 mm{sup 3} for examination of scintillation properties. BaMgF{sub 4} demonstrated {approx}70% transmittance in wavelength range above 170 nm, and strong emission peaking around 205 nm was observed under X-ray excitation. The absolute light yield of BaMgF{sub 4} was 1300{+-}100 ph/MeV, and the decay time profile showed two components as 0.57{+-}0.01 (70%) and 2.2{+-}0.31 (30%) ns at room temperature.

  18. Effect of Ba ions on the growth and mitochondrial metabolism of Mung bean seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Minton, G A; Wilson, R H

    1973-01-01

    The presence of high concentrations of BaCl/sub 2/ in vermiculite grown Mung bean (Phaseolus aureus) resulted in a reduction in shoot growth compared with plants grown in equivalent concentrations of CaCl/sub 2/. A high level of Ba ion was found in the mitochondria from plants grown at high Ba ion concentrations. Respiration rates of isolated mitochondria from plants grown at high levels of Ba were more rapid with all substrates tested, while the coupling parameters, including respiratory control with all substrates tested and ADP/O ratios with pyruvate-malate were partially reduced. These results are discussed as a possible mechanism of inhibition of plants grown in high-Ba soils. 12 references, 1 figure, 3 tables.

  19. Effect of BaSi2 template growth duration on the generation of defects and performance of p-BaSi2/n-Si heterojunction solar cells

    Science.gov (United States)

    Yachi, Suguru; Takabe, Ryota; Deng, Tianguo; Toko, Kaoru; Suemasu, Takashi

    2018-04-01

    We investigated the effect of BaSi2 template growth duration (t RDE = 0-20 min) on the defect generation and performance of p-BaSi2/n-Si heterojunction solar cells. The p-BaSi2 layer grown by molecular beam epitaxy (MBE) was 15 nm thick with a hole concentration of 2 × 1018 cm-3. The conversion efficiency η increased for films grown at long t RDE, owing to improvements of the open-circuit voltage (V OC) and fill factor (FF), reaching a maximum of η = 8.9% at t RDE = 7.5 min. However, η decreased at longer and shorter t RDE owing to lower V OC and FF. Using deep-level transient spectroscopy, we detected a hole trap level 190 meV above the valence band maximum for the sample grown without the template (t RDE = 0 min). An electron trap level 106 meV below the conduction band minimum was detected for a sample grown with t RDE = 20 min. The trap densities for both films were (1-2) × 1013 cm-3. The former originated from the diffusion of Ba into the n-Si region; the latter originated from defects in the template layer. The crystalline qualities of the template and MBE-grown layers were discussed. The root-mean-square surface roughness of the template reached a minimum of 0.51 nm at t RDE = 7.5 min. The a-axis orientation of p-BaSi2 thin films degraded as t RDE exceeded 10 min. In terms of p-BaSi2 crystalline quality and solar cell performance, the optimum t RDE was determined to be 7.5 min, corresponding to approximately 4 nm in thickness.

  20. Spatial heterogeneity regulates plant-pollinator networks across multiple landscape scales.

    Directory of Open Access Journals (Sweden)

    Eduardo Freitas Moreira

    Full Text Available Mutualistic plant-pollinator interactions play a key role in biodiversity conservation and ecosystem functioning. In a community, the combination of these interactions can generate emergent properties, e.g., robustness and resilience to disturbances such as fluctuations in populations and extinctions. Given that these systems are hierarchical and complex, environmental changes must have multiple levels of influence. In addition, changes in habitat quality and in the landscape structure are important threats to plants, pollinators and their interactions. However, despite the importance of these phenomena for the understanding of biological systems, as well as for conservation and management strategies, few studies have empirically evaluated these effects at the network level. Therefore, the objective of this study was to investigate the influence of local conditions and landscape structure at multiple scales on the characteristics of plant-pollinator networks. This study was conducted in agri-natural lands in Chapada Diamantina, Bahia, Brazil. Pollinators were collected in 27 sampling units distributed orthogonally along a gradient of proportion of agriculture and landscape diversity. The Akaike information criterion was used to select models that best fit the metrics for network characteristics, comparing four hypotheses represented by a set of a priori candidate models with specific combinations of the proportion of agriculture, the average shape of the landscape elements, the diversity of the landscape and the structure of local vegetation. The results indicate that a reduction of habitat quality and landscape heterogeneity can cause species loss and decrease of networks nestedness. These structural changes can reduce robustness and resilience of plant-pollinator networks what compromises the reproductive success of plants, the maintenance of biodiversity and the pollination service stability. We also discuss the possible explanations for

  1. Spatial heterogeneity regulates plant-pollinator networks across multiple landscape scales.

    Science.gov (United States)

    Moreira, Eduardo Freitas; Boscolo, Danilo; Viana, Blandina Felipe

    2015-01-01

    Mutualistic plant-pollinator interactions play a key role in biodiversity conservation and ecosystem functioning. In a community, the combination of these interactions can generate emergent properties, e.g., robustness and resilience to disturbances such as fluctuations in populations and extinctions. Given that these systems are hierarchical and complex, environmental changes must have multiple levels of influence. In addition, changes in habitat quality and in the landscape structure are important threats to plants, pollinators and their interactions. However, despite the importance of these phenomena for the understanding of biological systems, as well as for conservation and management strategies, few studies have empirically evaluated these effects at the network level. Therefore, the objective of this study was to investigate the influence of local conditions and landscape structure at multiple scales on the characteristics of plant-pollinator networks. This study was conducted in agri-natural lands in Chapada Diamantina, Bahia, Brazil. Pollinators were collected in 27 sampling units distributed orthogonally along a gradient of proportion of agriculture and landscape diversity. The Akaike information criterion was used to select models that best fit the metrics for network characteristics, comparing four hypotheses represented by a set of a priori candidate models with specific combinations of the proportion of agriculture, the average shape of the landscape elements, the diversity of the landscape and the structure of local vegetation. The results indicate that a reduction of habitat quality and landscape heterogeneity can cause species loss and decrease of networks nestedness. These structural changes can reduce robustness and resilience of plant-pollinator networks what compromises the reproductive success of plants, the maintenance of biodiversity and the pollination service stability. We also discuss the possible explanations for these relationships and

  2. The BaBar instrumented flux return performance: lessons learned

    CERN Document Server

    Anulli, F; Baldini, R; Band, H R; Bionta, R; Brau, J E; Brigljevic, V; Buzzo, A; Calcaterra, A; Carpinelli, M; Cartaro, C; Cavallo, N; Crosetti, G; De Nardo, Gallieno; De Sangro, R; Eichenbaum, A; Fabozzi, F; Falciai, D; Ferrarotto, F; Ferroni, F; Finocchiaro, G; Forti, F; Frey, R; Gatto, C; Graug; Iakovlev, N I; Iwasaki, M; Johnson, J R; Lange, D J; Lista, L; Lo Vetere, M; Lü, C; Macri, M; Messner, R; Moore, T B; Morganti, S; Neal, H; Neri, N; Palano, A; Paoloni, E; Paolucci, P; Passaggio, S; Pastore, F C; Patteri, P; Peruzzi, I; Piccolo, D; Piccolo, M; Piredda, G; Robutti, E; Roodman, A; Santroni, A; Sciacca, C; Sinev, N B; Soha, A; Strom, D; Tosi, S; Vavra, J; Wisniewski, W J; Wright, D M; Xie, Y; Zallo, A

    2002-01-01

    The BaBar Collaboration has operated an instrumented flux return (IFR) system covering over 2000 m sup 2 with resistive plate chambers (RPCs) for nearly 3 years. The chambers are constructed of bakelite sheets separated by 2 mm. The inner surfaces are coated with linseed oil. This system provides muon and neutral hadron detection for BaBar. Installation and commissioning were completed in 1998, and operation began mid-year 1999. While initial performance of the system reached design, over time, a significant fraction of the RPCs demonstrated significant degradation, marked by increased currents and reduced efficiency. A coordinated effort of investigations have identified many of the elements responsible for the degradation. This article presents our current understanding of the aging process of the BaBar RPCs along with the action plan to combat performance degradation of the IFR system.

  3. The new barium mercuride BaHg6 and ternary indium and gallium derivatives

    International Nuclear Information System (INIS)

    Wendorff, Marco; Röhr, Caroline

    2013-01-01

    Highlights: ► The new binary Hg-rich mercuride BaHg 6 crystallizes with a singular structure type. ► Ternary In substituted compounds are isotypic, whereas Ga substituted compounds are only structurally related. ► Structure relation to other Hg-rich alkali and alkaline earth mercurides. ► Discussion of covalent and metallic bonding aspects, as found by structure features and band structure calculations. - Abstract: The new binary barium mercuride BaHg 6 and the derived ternary indium and gallium containing compounds BaIn 1.2 Hg 4.8 and BaGa 0.8 Hg 5.2 were synthesized from melts of the elements, which were slowly cooled from 500 to 200 °C. Their crystal structures have been determined by means of single crystal X-ray diffraction. The binary mercuride BaHg 6 (Pnma, a = 1338.9(3), b = 519.39(13), c = 1042.6(4) pm, Z = 4, R1 = 0.0885) and the isotypic indium substituted compound BaIn 1.2 Hg 4.8 as well as the structurally related gallium mercuride BaGa 0.8 Hg 5.2 (Cmcm, a = 729.77(7), b = 1910.1(2), c = 507.48(5) pm, Z = 4, R1 = 0.0606) crystallize with new structure types. Common features of both structures are planar nets of five- and eight-membered Hg rings, stacked perpendicular to the shortest axes. According to their lengths, the Hg–Hg bonds can be classified into three groups: strong, short ones (I, 285–292 pm), which are only found inside the nets, and longer distances (II), still carrying bond critical points, around 300 pm. Further contacts (III) serve to complete the coordination spheres of Hg/M (320–358 pm). The overall coordination numbers of Hg/M range from 10 to 13. The Ba cations are positioned in the centers of the octagons of the Hg/M nets, thus exhibiting a 5:8:5, i.e. 18, coordination by Hg/M atoms. DFT calculations of the electronic band structure of pure BaHg 6 and ordered models of the indium ( ′ BaInHg 5 ′ ) and the gallium ( ′ BaGaHg 5 ′ ) mercurides were performed using the FP-LAPW method. The calculated Bader charges

  4. Thermodynamic model for the solubility of BaSeO4(cr) in the aqueous Ba2+-SeO42--Na+-H+-OH--H2O system. Extending to high selenate concentrations

    International Nuclear Information System (INIS)

    Rai, Dhanpat; Felmy, Andrew R.; Kitamura, Akira; Yoshikawa, Hideki; Doi, Reisuke; Yoshida, Yasushi; Moore, Dean A.

    2014-01-01

    The aqueous solubility of BaSeO 4 (cr) was studied at 23 ± 2 C as a function of Na 2 SeO 4 concentrations (0.0001 to 4.1 mol kg -1 ) and equilibration periods (3 to 596 d). The equilibrium, approached from both the under- and over-saturation directions, in this system was reached rather rapidly (≤ 3d). The SIT and Pitzer's ion-interaction models were used to interpret these data and the predictions based on both of these models agreed closely with the experimental data. Thermodynamic analyses of the data show that BaSeO 4 (cr) is the solubility-controlling phase for Na 2 SeO 4 concentrations -1 . The log 10 K 0 value for the BaSeO 4 (cr) solubility product (BaSeO 4 (cr) ↔ Ba 2+ + SeO 4 2- ) calculated by the SIT and Pitzer models were very similar (-7.32 ± 0.07 with Pitzer and -7.25 ± 0.11 with SIT). Although the BaSeO 4 (cr) solubility product and Ba concentrations as a function of Na 2 SeO 4 concentrations predicted by both the SIT and Pitzer models are similar, the models required different sets of fitting parameters. For examples, (1) interpretations using the SIT model required the inclusion of Ba(SeO 4 ) 2 2- species with log 10 K 0 = 3.44 ± 0.12 for the reaction (Ba 2+ + 2SeO 4 2- ↔ Ba(SeO 4 ) 2 2- ), whereas these species are not needed for Pitzer model, and (2) at Na 2 SeO 4 concentrations > 0.59 mol kg -1 it was also possible to calculate the value for log 10 K 0 for the solubility product of a proposed double salt (Na 2 Ba(SeO 4 ) 2 (s) ↔ 2Na + + Ba 2+ + 2SeO 4 2- ) which for the SIT model is -(8.70 ± 0.29) whereas for the Pitzer model it is -(9.19 ± 0.19). The ion-interaction/ion-association parameters hitherto unavailable for both the SIT and Pitzer models required to fit these extensive data extending to as high ionic strengths as 12.3 mol kg -1 were determined. The model developed in this study is consistent with all of the reliable literature data, which was also used to extend the model to barium concentrations as high as 0.22 mol kg

  5. Preparation and self-assembly of nanostructured BaCrO4 from CTAB reverse microemulsions

    International Nuclear Information System (INIS)

    Li Zhonghao; Zhang Jianling; Du Jimin; Han Buxing; Mu Tiancheng; Gao Yanan; Liu Zhimin

    2005-01-01

    Well-defined superstructures of rectangular-shaped BaCrO 4 and extensive network of BaCrO 4 nanoparticles constructed by self-assembly were prepared in cetyltrimethylammonium bromide (CTAB) reverse microemulsions. The effects of aging time and reactant concentrations on the morphology and the self-assemble pattern of the nanostructured BaCrO 4 were investigated. TEM combined with the electron diffraction was used to characterize the morphology and the crystal structure of the prepared nanostructured BaCrO 4 at different conditions

  6. Muon spin depolarization in Gd- and EuBa2Cu3Ox

    International Nuclear Information System (INIS)

    Cooke, D.W.; Hutson, R.L.; Kwok, R.S.; Maez, M.; Rempp, H.; Schillaci, M.E.; Smith, J.L.; Willis, J.O.; Lichti, R.L.; Chan, K.C.; Boekema, C.; Weathersby, S.; Oostens, J.

    1989-01-01

    Positive muon spin rotation (μSR) measurements on Gd- and EuBa 2 Cu 3 O x (x ∼ 7) have been conducted in the temperature interval 4 - 300 K. For each sample, muons stop both at grain boundaries and within the superconducting grains. Measured magnetic field penetration depths are 1550 and 1900 Angstrom for two specimens of GdBa 2 Cu 3 O x , and 1350 Angstrom for EuBa 2 Cu 3 O x

  7. Dependence of transfer number of fluorine on cation type in glasses of Ba(PO3)2-MeF2 systems (Me=Ba,Sr,Ca,Mg)

    International Nuclear Information System (INIS)

    Pronkin, A.A.

    1978-01-01

    The influence of Ba, Sr, Ca, Mg cations on transfer numbers of fluorine in glasses of Ba(PO 3 ) 2 - MeF 2 pseudobinary systems is studied. Transfer numbers are essentially different in one and the same fluorine ion concentration in glasses, containing various alkali-earth cations: increase of the cation field force brings about decrease of the transfer numbers of fluorine, and the glass-formation region in the Ba-Sr-Ca-Mg series rises. The dependence of transfer numbers of fluorine on the fluorine concentration logarithm is presented. It is established, that alkali-earth metals influence the transfer numbers of fluorine on account of selective interaction with the phosphate constituent of glass structure

  8. Characterization of the insulator barrier and the superconducting transition temperature in GdBa{sub 2}Cu{sub 3}O{sub 7−δ}/BaTiO{sub 3} bilayers for application in tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, H., E-mail: henrynavarro@cab.cnea.gov.ar; Sirena, M.; Haberkorn, N. [Instituto Balseiro, Universidad Nacional de Cuyo and CNEA, 8400 Bariloche (Argentina); Centro Atómico Bariloche, Comisión Nacional de Energía Atómica. Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Yang, Ilkyu [Department of Physics, Pohang University of Science and Technology, Pohang (Korea, Republic of); Kim, Jeehoon [Department of Physics, Pohang University of Science and Technology, Pohang (Korea, Republic of); CALDES, Institute for Basic Science, Pohang (Korea, Republic of)

    2015-07-28

    The optimization of the superconducting properties in a bottom electrode and the quality of an insulator barrier are the first steps in the development of superconductor/insulator/superconductor tunnel junctions. Here, we study the quality of a BaTiO{sub 3} tunnel barrier deposited on a 16 nm thick GdBa{sub 2}Cu{sub 3}O{sub 7−δ} thin film by using conductive atomic force microscopy. We find that the tunnel current is systematically reduced (for equal applied voltage) by increasing the BaTiO{sub 3} barrier thickness between 1.6 and 4 nm. The BaTiO{sub 3} layers present an energy barrier of ≈1.2 eV and an attenuation length of 0.35–0.5 nm (depending on the applied voltage). The GdBa{sub 2}Cu{sub 3}O{sub 7−δ} electrode is totally covered by a BaTiO{sub 3} thickness above 3 nm. The presence of ferroelectricity was verified by piezoresponse force microscopy for a 4 nm thick BaTiO{sub 3} top layer. The superconducting transition temperature of the bilayers is systematically suppressed by increasing the BaTiO{sub 3} thickness. This fact can be associated with stress at the interface and a reduction of the orthorhombicity of the GdBa{sub 2}Cu{sub 3}O{sub 7−δ}. The reduction in the orthorhombicity is expected by considering the interface mismatch and it can also be affected by reduced oxygen stoichiometry (poor oxygen diffusion across the BaTiO{sub 3} barrier)

  9. The Synthesis of BaAl2O4 Powder with High Surface Area%高比表面积BaAl2O4粉体合成研究

    Institute of Scientific and Technical Information of China (English)

    乔彦辉; 顾士甲; 王明辉; 田元; 李欢; 江莞

    2017-01-01

    BaAl2O4是优良的NOx存储催化剂材料,同时也是一种理想的荧光基体材料,受到了研究人员的广泛关注.但是一般的BaAl2O4粉体由于比表面积相对较小,使用受到了限制.虽然纳米颗粒有大的比表面积,但其团聚的缺陷严重限制了其应用.本文采用了一种简单的软模板法合成了BaAl2O4粉体.该粉体经过XRD表征表明为BaAl2O4,经BET表征具有较大比表面积.BaAl2O4粉体不仅化学稳定性好,而且具有相对较大的比表面积.其合成方法节省能源、生产效率高,在特定场合极有可能替代普通粉体做实际应用.%BaAl2O4 is an excellent NOx storage catalyst material. At the same time, it is also an ideal fluorescent matrix material and draws extensive attention. However, the general BaAl2O4 powder is limited by the relatively small surface area. Although the nanoparticles have larger surface area, the defect of their aggregation severely limits their applications. In this study, BaAl2O4 powder was synthesized by a simple soft template method, which not only had a good chemical stability, but also had a relatively large surface area. After characterizing by XRD, BET and TEM, the powder proved exactly the BaAl2O4 with a larger surface area. The synthesis method in this paper has high production efficiency and energy efficiency, and the powder is likely to replace the commonly-used powder on particular occasions.

  10. Electrical properties and structure of glasses in the Ba(PO3)2-MF2 systems, where M = Mg, Ca, Sr, Ba

    International Nuclear Information System (INIS)

    Sokolov, I.A.; Tarlakov, Yu.P.; Murin, I.V.; Pronkin, A.A.

    2000-01-01

    Using the methods of conductometry and IR spectroscopy the concentrational dependences of electric conductivity are studied, the nature of current carriers is determined, the concentrational dependence of transfer numbers is ascertained and structural changes in glasses of the system Ba(PO 3 ) 2 -MF 2 (M = Mg, Ca, Sr, Ba), depending on MF 2 content, are considered. It is shown that F - ions take part in electric current transfer. Influence of crystallochemical nature of alkaline-earth cations on physicochemical properties and structure of the glasses studied is analyzed [ru

  11. The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA.

    Science.gov (United States)

    Sayapathi, Balachandar S; Su, Anselm Ting; Koh, David

    2014-10-01

    Development of noise-induced hearing loss is reliant on a few factors such as frequency, intensity, and duration of noise exposure. The occurrence of this occupational malady has doubled from 120 million to 250 million in a decade. Countries such as Malaysia, India, and the US have adopted 90 dBA as the permissible exposure limit. According to the US Occupational Safety and Health Administration (OSHA), the exposure limit for noise is 90 dBA, while that of the US National Institute of Occupational Safety and Health (NIOSH) is 85 dBA for 8 hours of noise exposure. This study aimed to assess the development of hearing threshold levels beyond 25 dBA on adoption of 85 dBA as the permissible exposure limit compared to 90 dBA. This is an intervention study done on two automobile factories. There were 203 employees exposed to noise levels beyond the action level. Hearing protection devices were distributed to reduce noise levels to a level between the permissible exposure limit and action level. The permissible exposure limits were 90 and 85 dBA in factories 1 and 2, respectively, while the action levels were 85 and 80 dBA, respectively. The hearing threshold levels of participants were measured at baseline and at first month of postshift exposure of noise. The outcome was measured by a manual audiometer. McNemar and chi-square tests were used in the statistical analysis. We found that hearing threshold levels of more than 25 dBA has changed significantly from pre-intervention to post-intervention among participants from both factories (3000 Hz for the right ear and 2000 Hz for the left ear). There was a statistically significant association between participants at 3000 Hz on the right ear at 'deteriorated' level ( χ² (1) = 4.08, φ = - 0.142, P = 0.043), whereas there was worsening of hearing threshold beyond 25 dBA among those embraced 90 dBA. The adoption of 85 dBA as the permissible exposure limit has preserved hearing threshold level among participants at 3000 Hz

  12. Nuclear charge radii and nuclear moments of neutron deficient Ba isotopes from high resolution laser spectroscopy

    International Nuclear Information System (INIS)

    Nowicki, G.; Bekk, K.; Goering, S.; Hanser, A.; Rebel, H.; Schatz, G.

    1978-07-01

    Isotope shifts and hyperfine structure of the BaI 6s 2 1 S 0 -6s6p 1 P 1 transitions (lambda = 553.6 nm) in neutron deficient Ba nuclides (N 131 Ba, 128 Ba, in addition to remeasurements of all stable Ba nuclides. The extracted values of delta 2 >, the observed odd-even staggering and the nuclear moments are discussed in the light of other theoretical and experimental nuclear structure studies of the region 50 [de

  13. Variations of force constants, M-O distances and bond order in solid solutions between Ba/sub 2/MgUO/sub 6/ and Ba/sub 2/MgWO/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Fadini, A [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

    1977-12-01

    In solid solutions between the 1:1 ordered perovskites Ba/sub 2/MgUO/sub 6/ and Ba/sub 2/MgWO/sub 6/ (system Ba/sub 2/MgUsub(1-x)Wsub(x)O/sub 6/) the force constants of the UO/sub 6/ and WO/sub 6/ octahedras are variied. The valence force constants fsub(MO) tend to adjust for each x. The bond order and the M-O distances are reported as well.

  14. Sediment pollution in margins of the Lake Guaíba, Southern Brazil.

    Science.gov (United States)

    de Andrade, Leonardo Capeleto; Tiecher, Tales; de Oliveira, Jessica Souza; Andreazza, Robson; Inda, Alberto Vasconcellos; de Oliveira Camargo, Flávio Anastácio

    2017-12-02

    Sediments are formed by deposition of organic and inorganic particles on depth of water bodies, being an important role in aquatic ecosystems, including destination and potential source of essential nutrients and heavy metals, which may be toxic for living organisms. The Lake Guaíba supplies water for approximately two million people and it is located in the metropolitan region of Porto Alegre, Rio Grande do Sul State, Brazil. Thus, the aim of this study was to evaluate the sediment pollution in the margins of Lake Guaíba in the vicinity of Porto Alegre city. Surface sediment was sampled in 12 sites to assess the concentration of several elements (C, N, P, Fe, Al, Ca, Mg, Na, K, Mn, Ba, Zn, V, Pb, Cu, Cr, Ni, Cd, Mo, and Se) and the mineralogical composition. Sediment in margins of Lake Guaíba presented predominantly (> 95%) sandy fraction in all samples, but with significant differences between evaluated sites. Sediments in the margins of Lake Guaíba showed indications of punctual water pollution with Pb, Cu, Cr, Ni, TOC, TKN, and P, mainly derived from urban streams that flow into the lake. In order to solve these environmental liabilities, public actions should not focus only on Guaíba, but also in the streams that flow into the lake.

  15. Photoluminescent BaMoO4 nanopowders prepared by complex polymerization method (CPM)

    International Nuclear Information System (INIS)

    Azevedo Marques, Ana Paula de; Melo, Dulce M.A. de; Paskocimas, Carlos A.; Pizani, Paulo S.; Joya, Miryam R.; Leite, Edson R.; Longo, Elson

    2006-01-01

    The BaMoO 4 nanopowders were prepared by the Complex Polymerization Method (CPM). The structure properties of the BaMoO 4 powders were characterized by FTIR transmittance spectra, X-ray diffraction (XRD), Raman spectra, photoluminescence spectra (PL) and high-resolution scanning electron microscopy (HR-SEM). The XRD, FTIR and Raman data showed that BaMoO 4 at 300 deg. C was disordered. At 400 deg. C and higher temperature, BaMoO 4 crystalline scheelite-type phases could be identified, without the presence of additional phases, according to the XRD, FTIR and Raman data. The calculated average crystallite sizes, calculated by XRD, around 40 nm, showed the tendency to increase with the temperature. The crystallite sizes, obtained by HR-SEM, were around of 40-50 nm. The sample that presented the highest intensity of the red emission band was the one heat treated at 400 deg. C for 2 h, and the sample that displayed the highest intensity of the green emission band was the one heat treated at 700 deg. C for 2 h. The CPM was shown to be a low cost route for the production of BaMoO 4 nanopowders, with the advantages of lower temperature, smaller time and reduced cost. The optical properties observed for BaMoO 4 nanopowders suggested that this material is a highly promising candidate for photoluminescent applications

  16. Positron annihilation lifetime study of positive temperature coefficient BaTiO3 samples

    International Nuclear Information System (INIS)

    Ling Chen; Mingkang Teng; Guanghou Wang; Xiaoyun Li; Tianchang Lu

    1989-01-01

    In order to investigate the doped vacancies in BaTiO 3 samples as well as their influence on the positive temperature coefficient (PTC) the positron annihilation lifetime spectroscopy was applied. Two groups of BaTiO 3 samples with BaO excess were prepared by doping different concentrations of La 2 O 3 and Nb 2 O 5 , respectively in the range from 0.1 to 3 at%. A third group of samples of two Sb-doped PTC BaTiO 3 semiconductors with excess BaO or TiO 2 were studied by the aid of positron technique before and after being reduced. It is shown that the positron lifetime parameters are sensitive to changes in the vacancy concentration in BaTiO 3 ceramics near the 0.1 mol% region. But they are almost unchanged during reduction processing; the resistivity of samples changed by one to two orders of magnitude through the reduction. It can be concluded that the PTC effect is due to oxygen on the grain boundary rather than vacancies, and that the Heywang-Jonker model is more reasonable

  17. Thermoelectric properties of Cu/Ag doped type-III Ba24Ge100 clathrates

    Science.gov (United States)

    Fu, Jiefei; Su, Xianli; Yan, Yonggao; Liu, Wei; Zhang, Zhengkai; She, Xiaoyu; Uher, Ctirad; Tang, Xinfeng

    2017-09-01

    Type-III Ba24Ge100 clathrates possess low thermal conductivity and high electrical conductivity at room temperature and, as such, have a great potential as thermoelectric materials for power generation. However, the Seebeck coefficient is very low due to the intrinsically high carrier concentration. In this paper, a series of Ba24CuxGe100-x and Ba24AgyGe100-y specimens were prepared by vacuum melting combined with the subsequent spark plasma sintering (SPS) process. Doping Cu or Ag on the Ge site not only suppresses the concentration of electrons but it also decreases the thermal conductivity. In addition, the carrier mobility and the Seebeck coefficient increase due to the decrease in the carrier concentration. Thus, the power factor is greatly improved, leading to an improvement in the dimensionless figure of merit ZT. Cu-doped Ba24Cu6Ge94 reaches the maximum ZT value of about 0.17 at 873 K, while Ag-doped Ba24Ag6Ge94 attains the dimensionless figure of merit ZT of 0.31 at 873 K, more than 2 times higher value compared to un-doped Ba24Ge100.

  18. Compounds of type Ba/sub 2/Bsup(III)Ossup(V)O/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Treiber, U; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1981-07-01

    The black perovskites of type Ba/sub 2/Bsup(III)Ossup(V)O/sub 6/ crystallize cubic (Bsup(III) = Pr, Nd, Sm-Lu, Y) and rhombohedral (Bsup(III) = La) respectively; the cell volumina decrease linearily with (rsub(B)sup(III))/sup 3/. Intensity calculations on powder data for Ba/sub 2/YOsO/sub 6/ (space group Fm3m-Osub(h)/sup 5/) and Ba/sub 2/LaOsO/sub 6/ (space group R-3m-Dsub(3d)/sup 5/) gave the intensity related R'values of 4.6% and 5.0% respectively. The results of the vibrational spectroscopic investigations are reported in common with the bond orders, M-O distances and mean amplitudes and compared with the corresponding values of the series Ba/sub 2/Bsup(III)Irsup(V)O/sub 6/ and Ba/sub 2/Bsup(III)Rusup(V)O/sub 6/.

  19. Influence of Ba/Fe mole ratios on magnetic properties, crystallite size and shifting of X-ray diffraction peaks of nanocrystalline BaFe12O19 powder, prepared by sol gel auto combu

    Science.gov (United States)

    Suastiyanti, Dwita; Sudarmaji, Arif; Soegijono, Bambang

    2012-06-01

    Barium hexaferrite BaFe12O19 (BFO) is of great importance as permanent magnets, particularly for magnetic recording as well as in microwave devices. Nano-crystalline BFO powders were prepared by sol gel auto combustion method in citric acid - metal nitrates system. Hence the mole ratios of Ba/Fe were variated at 1:12; 1:11.5 and 1:11. Ratio of cation to fuel was fixed at 1:1. An appropriate amount of amonia solution was added dropwise to this solution with constant stirring until the PH reached 7 in all cases. Heating at 850oC for 10 hours for each sample to get final formation of BFO nanocrystalline. The data from XRD showing the lattice parameters a,c and the unit-cell volume V, confirm that BFO with ratio 1:12 has same crystall parameters with ratio 1:11. Ratio of Ba/Fe 1:12 and 1:11 have diffraction pattern similarly at almost each 2 θ for each samples. Ratio of Ba/Fe 1: 11.5 has the finest crystallite size 22 nm. Almost diffraction pattern peaks of Ba/Fe 1:11.5 move to the left from of Ba/Fe 1:12 then return to diffraction pattern of Ba/Fe 1:12 for Ba/Fe 1:11. SEM observations show the particle size less than 100 nm and the same shape for each sample. Ratio of Ba/Fe 1: 12 gives the highest intrinsic coercive Hc = 427.3 kA/m. The highest remanent magnetization is at ratio 1:11 with Mr = 0.170 T. BFO with mole ratio 1:11.5 has the finest grain 22 nm, good magnetic properties and the highest value of best FoM 89%.

  20. Configuration Database for BaBar On-line

    International Nuclear Information System (INIS)

    Salnikov, Andrei

    2003-01-01

    The configuration database is one of the vital systems in the BaBar on-line system. It provides services for the different parts of the data acquisition system and control system, which require run-time parameters. The original design and implementation of the configuration database played a significant role in the successful BaBar operations since the beginning of experiment. Recent additions to the design of the configuration database provide better means for the management of data and add new tools to simplify main configuration tasks. We describe the design of the configuration database, its implementation with the Objectivity/DB object-oriented database, and our experience collected during the years of operation

  1. Microstructural properties of BaTiO{sub 3} ceramics and thin films

    Energy Technology Data Exchange (ETDEWEB)

    Fundora C, A.; Portelles, J.J.; Siqueiros, J.M. [Posgrado en Fisica de Materiales, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada. Apartado Postal 2861, 22800 Ensenada, Baja California (Mexico)

    2000-07-01

    A microstructural study of BaTiO{sub 3} ceramics obtained by the conventional ceramic method is presented. Targets were produced to grow BaTiO{sub 3} thin films by pulsed laser deposition on Pt/Ti/Si (100) substrates. X-ray diffraction, Auger Electron Spectroscopy, X-ray Photon Spectroscopy and Scanning Electron Microscopy were used to study the properties of the BaTiO{sub 3} ceramic samples and thin films, as deposited and after an annealing process. (Author)

  2. Structural, optical and electronic properties of K2Ba(NO3)4 crystal

    Science.gov (United States)

    Isaenko, L. I.; Korzhneva, K. E.; Goryainov, S. V.; Goloshumova, A. A.; Sheludyakova, L. A.; Bekenev, V. L.; Khyzhun, O. Y.

    2018-02-01

    Nitrate crystals reveal nonlinear optical properties and could be considered as converters of laser radiation in the short-wave region. The conditions for obtaining and basic properties of K2Ba(NO3)4 double nitrate crystals were investigated. Crystal growth was implemented by slow cooling in the temperature range of 72-49 °C and low rate evaporation. The structural analysis of K2Ba(NO3)4 formation on the basis of two mixed simple nitrate structures is discussed. The main groups of oscillations in K2Ba(NO3)4 crystal were revealed using Raman and IR spectroscopy, and the table of vibrations for this compound was compiled. The electronic structure of K2Ba(NO3)4 was elucidated in the present work from both experimental and theoretical viewpoints. In particular, X-ray photoelectron spectroscopy (XPS) was employed in the present work to measure binding energies of the atoms constituting the titled compound and its XPS valence-band spectrum for both pristine and Ar+ ion-bombarded surfaces. Further, total and partial densities of states of constituent atoms of K2Ba(NO3)4 have been calculated. The calculations reveal that the O 2p states dominate in the total valence-band region of K2Ba(NO3)4 except of its bottom, where K 3p and Ba 5p states are the principal contributors, while the bottom of the conduction band is composed mainly of the unoccupied O 2p states, with somewhat smaller contributions of the N 2p∗ states as well. With respect to the occupation of the valence band by the O 2p states, the present band-structure calculations are confirmed by comparison on a common energy scale of the XPS valence-band spectrum and the X-ray emission O Kα band for the K2Ba(NO3)4 crystal under study. Furthermore, the present calculations indicate that the K2Ba(NO3)4 compound is a direct-gap material.

  3. High Pressure Properties of a Ba-Cu-Zn-P Clathrate-I

    Directory of Open Access Journals (Sweden)

    Juli-Anna Dolyniuk

    2016-08-01

    Full Text Available The high pressure properties of the novel tetrel-free clathrate, Ba8Cu13.1Zn3.3P29.6, were investigated using synchrotron powder X-ray diffraction. The pressure was applied using a diamond anvil cell. No structural transitions or decomposition were detected in the studied pressure range of 0.1–7 GPa. The calculated bulk modulus for Ba8Cu13.1Zn3.3P29.6 using a third-order Birch-Murnaghan equation of state is 65(6 GPa at 300 K. This bulk modulus is comparable to the bulk moduli of Ge- and Sn-based clathrates, like A8Ga16Ge30 (A = Sr, Ba and Sn19.3Cu4.7P22I8, but lower than those for the transition metal-containing silicon-based clathrates, Ba8TxSi46−x, T = Ni, Cu; 3 ≤ x ≤ 5.

  4. Molecular glues for manipulating enzymes: trypsin inhibition by benzamidine-conjugated molecular glues† †Electronic supplementary information (ESI) available: Synthesis of TEG–BA, Gluen–BA, mGluen–BA and Gluen–Ph; 1H NMR, 13C NMR, MALDI-TOF MS, electronic absorption, and CD spectra; zeta potential distributions; SLS plots; DLS histograms; and related experimental procedures. See DOI: 10.1039/c5sc00524h Click here for additional data file.

    Science.gov (United States)

    Mogaki, Rina

    2015-01-01

    Water-soluble bioadhesive polymers bearing multiple guanidinium ion (Gu+) pendants at their side-chain termini (Gluen–BA, n = 10 and 29) that were conjugated with benzamidine (BA) as a trypsin inhibitor were developed. The Gluen–BA molecules are supposed to adhere to oxyanionic regions of the trypsin surface, even in buffer, via a multivalent Gu+/oxyanion salt-bridge interaction, such that their BA group properly blocks the substrate-binding site. In fact, Glue10–BA and Glue29–BA exhibited 35- and 200-fold higher affinities for trypsin, respectively, than a BA derivative without the glue moiety (TEG–BA). Most importantly, Glue10–BA inhibited the protease activity of trypsin 13-fold more than TEG–BA. In sharp contrast, mGlue27–BA, which bears 27 Gu+ units along the main chain and has a 5-fold higher affinity than TEG–BA for trypsin, was inferior even to TEG–BA for trypsin inhibition. PMID:28706668

  5. In vitro anticancer potential of BaCO3 nanoparticles synthesized via green route.

    Science.gov (United States)

    Nagajyothi, P C; Pandurangan, Muthuraman; Sreekanth, T V M; Shim, Jaesool

    2016-03-01

    Green synthesis of nanoparticles is a growing research area because of their potential applications in nanomedicine. Barium carbonate nanoparticles (BaCO3 NPs) were synthesized using an aqueous extract of Mangifera indica seed as a reducing agent. These particles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Transmission electron microscopy (TEM), selected area electron diffraction (SAED), Energy-dispersive-X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) analysis. HR-TEM images are confirmed that green synthesized BaCO3 NPs have spherical, triangular and uneven shapes. EDX analysis confirmed the presence of Ba, C and O. The peaks at 2θ of 19.45, 23.90, 24.29, 27.72, 33.71, 34.08, 34.60, 41.98, 42.95, 44.18, 44.85, and 46.78 corresponding to (110), (111), (021), (002), (200), (112), (130), (221), (041), (202), (132) and (113) showed that BaCO3 NPs average size was ~18.3 nm. SAED pattern confirmed that BaCO3 NPs are crystalline nature. BaCO3 NPs significantly inhibited cervical carcinoma cells, as evidenced by cytotoxicity assay. Immunofluorescence and fluorescence assays showed that BaCO3 NPs increased the expression and activity of caspase-3, an autocatalytic enzyme that promotes apoptosis. According to the results, green synthesis route has great potential for easy, rapid, inexpensive, eco-friendly and efficient development of novel multifunctional nanoparticles for the treatment of cancer. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Growth of single crystals of BaFe12O19 by solid state crystal growth

    International Nuclear Information System (INIS)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-01-01

    Single crystals of BaFe 12 O 19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe 12 O 19 are buried in BaFe 12 O 19 +1 wt% BaCO 3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe 12 O 19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe 12 O 19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth. - Highlights: • Single crystals of BaFe 12 O 19 are grown by solid state crystal growth. • A single crystal up to ∼130 μm thick (c-axis direction) grows on the seed crystal. • The single crystal and surrounding ceramic matrix have similar composition. • Micro-Raman scattering shows the single crystal has the BaFe 12 O 19 structure.

  7. High-pressure densified solid solutions of alkaline earth hexaborides (Ca/Sr, Ca/Ba, Sr/Ba) and their high-temperature thermoelectric properties

    International Nuclear Information System (INIS)

    Gürsoy, M.; Takeda, M.; Albert, B.

    2015-01-01

    Solid solutions of alkaline earth hexaborides were synthesized and densified by spark plasma sintering at 100 MPa. The high-temperature thermoelectric properties (Seebeck coefficients, electrical and thermal diffusivities, heat capacities) were measured between room temperature and 1073 K. CaB 6 , SrB 6 , BaB 6 and the ternary hexaborides Ca x Sr 1−x B 6 , Ca x Ba 1−x B 6 , Sr x Ba 1−x B 6 (x = 0.25, 0.5, 0.75) are n-type conducting compounds over the whole compositional and thermal ranges. The values of the figure of merit ZT for CaB 6 (ca. 0.3 at 1073 K) were found to be significantly increased compared to earlier investigations which is attributed to the densification process. - Highlights: • Solid solutions of alkaline earth hexaborides were synthesized. • High-temperature thermoelectric properties of mixed calcium borides are excellent. • Spark plasma source densification results in high ZT values. • Borides are rare-earth free and refractory materials

  8. Influence of Impurities on the Luminescence of Er3+ Doped BaTiO3 Nanophosphors

    Directory of Open Access Journals (Sweden)

    G. D. Webler

    2014-01-01

    Full Text Available The influence of the presence of barium carbonate (BaCO3 phase on the luminescence properties of barium titanate nanocrystals (BaTiO3 powders was investigated. Structural and optical characterizations of erbium (Er3+ doped BaTiO3 synthesized by the sol-emulsion-gel were performed. Using Fourier transform infrared spectroscopy and X-ray powder diffraction, we identified the presence of impurities related to BaCO3 and quantified its fraction. It was observed that the presence of BaCO3 phase, even at low levels, depletes significantly the infrared-to-visible upconverted luminescence efficiency of the produced nanopowders.

  9. From Ba{sub 3}Ta{sub 5}O{sub 14}N to LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2}: Decreasing the optical band gap of a photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Anke, B. [Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Bredow, T. [Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Universität Bonn, Beringstr. 4, 53115 Bonn (Germany); Pilarski, M.; Wark, M. [Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg (Germany); Lerch, M., E-mail: martin.lerch@tu-berlin.de [Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany)

    2017-02-15

    Yellow LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} was successfully synthesized as phase-pure material crystallizing isostructurally to previously reported Ba{sub 3}Ta{sub 5}O{sub 14}N and mixed-valence Ba{sub 3}Ta{sup V}{sub 4}Ta{sup IV}O{sub 15}. The electronic structure of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} was studied theoretically with the range-separated hybrid method HSE06. The most stable structure was obtained when lanthanum was placed on 2a and nitrogen on 4h sites confirming Pauling's second rule. By incorporating nitrogen, the measured band gap decreases from ∼3.8 eV for the oxide via 2.74 eV for Ba{sub 3}Ta{sub 5}O{sub 14}N to 2.63 eV for the new oxide nitride, giving rise to an absorption band well in the visible-light region. Calculated fundamental band gaps confirm the experimental trend. The atom-projected density of states has large contributions from N2p orbitals close to the valence band edge. These are responsible for the observed band gap reduction. Photocatalytic hydrogen formation was investigated and compared with that of Ba{sub 3}Ta{sub 5}O{sub 14}N revealing significantly higher activity for LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} under UV-light. - Graphical abstract: X-ray powder diffraction pattern of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} with the results of the Rietveld refinements. Inset: Unit cell of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} and polyhedral representation of the crystal structure. - Highlights: • Synthesis of a new oxide nitride LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2}. • Refinement of the crystal structure. • Quantum chemical calculations provided band gap close to the measured value. • New phase shows a higher photocatalytic H{sub 2} evolution rate compared to prior tested Ba{sub 3}Ta{sub 5}O{sub 14}N.

  10. Wet chemical synthesis of LiBaF{sub 3} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Vartika S., E-mail: svmoharil@yahoo.com [Physics Department, Shri Ramdeobaba K.N. Engineering College, Katol Road, Nagpur 440 013 (India); Joshi, C.P. [Physics Department, Shri Ramdeobaba K.N. Engineering College, Katol Road, Nagpur 440 013 (India); Moharil, S.V. [Department of Physics, R.T.M. Nagpur University, Nagpur 440 010 (India)

    2013-12-05

    Highlights: •LiBaF{sub 3}:RE{sup 3+} phosphors synthesized by a simple wet chemical method. •Ce{sup 3+} and Tb{sup 3+} emissions observed in as-prepared powders without any thermal treatment. •Intense Eu{sup 2+} emission observed after annealing in reductive atmosphere. -- Abstract: LiBaF{sub 3} has great potential applications as X-ray storage phosphor, slow neutron imaging, scintillator, vacuum ultraviolet (VUV) optical lithography, etc. Conventionally, LiBaF{sub 3} is prepared by solid state reaction between the constituent fluorides. However, the preparation of phase pure material and especially single crystals is rather tricky due to incongruent melting. For the first time, a wet chemical preparation of rare earth activated LiBaF{sub 3} is described here. As precipitated powders containing Ce{sup 3+} or Tb{sup 3+} exhibited characteristic luminescence. For observing Eu{sup 2+} emission, it was necessary to heat the powders in a reductive atmosphere. It is suggested that phosphors prepared by this method may prove useful in applications like OSL, X-ray imaging, etc. which do not require large single crystals.

  11. Development of BaSO4:Eu thermoluminescence phosphor

    International Nuclear Information System (INIS)

    Madhusoodanan, U.; Jose, M.T.; Lakshmanan, A.R.

    1999-01-01

    A highly sensitive thermoluminescence (TL) phosphor based on BaSO 4 :Eu was developed following the coprecipitation technique and firing in argon atmosphere at 1123 K. Photoluminescence studies confirm that firing in argon atmosphere instead of air increased the incorporation of Eu ions in 2+ valence state. At low γ-ray doses, its TL sensitivity is nearly 2 to 3 times higher than that of CaSO 4 :Dy phosphor. The other salient features of this BaSO 4 :Eu TL phosphor are a constant glow curve shape and a nearly linear γ-ray dose response

  12. History of the Balkan Stomatological Society (BaSS

    Directory of Open Access Journals (Sweden)

    Todorović Ljubomir

    2014-11-01

    Full Text Available Some of the main activities of the Balkan Stomatological Society (BaSS over a rich 19-year history are presented. These activities have been aimed at improving oral health care provided by the dentists throughout the Balkans, and to establish ties of friendship and collaboration between researchers and clinicians in this region, creating a foundation for mutual understanding and peace. To accomplish these goals, the BaSS annually organizes congresses and publishes a scientific journal, beside many other activities, such as public oral health promotion, bringing into accordance study programmes and curricula, supporting student exchange programmes, etc.

  13. The study of the effect of Ba coverage through the accelerations lifetime of activated BaO/SrO cathodes

    International Nuclear Information System (INIS)

    Hashim, A.A.; Ray, A.K.; Hassan, A.K.; Barratt, D.S.

    2005-01-01

    A novel type of BaO/SrO oxide cathode with 5% addition of Ni powder by weight on a Ni cap containing an activating impurity was studied. The conductivity and the electron activation energy were studied as a function of temperature in the range of 300-1200 K after conversion and activation of the cathode at 1200 K for 1 h. The experimental results yield three values for the activation energy of 1.49, 2.23 and 3.3 eV, which are close to BaO band structure parameters with a small shift due to the effect of other oxide components and metallic fraction additions. The experiments furthermore confirm that the current density of the cathode was enhanced at high temperature range with the long operation. The conduction mechanisms observed a metallic conduction at low temperature after operation for several 100 h due to improvements in the Ba coverage layer on the grains of oxide layer. Additionally, there appears a qualified conduction stability of the current density J = 10-45 mA cm -2 at the acceleration temperature range of 1100-1150 K under the duty of low voltage. The low voltage duty V = 30 mV is focused on the conduction electrons faraway from the emission electrons

  14. Oxygen excess in the '114' cobaltite hexagonal structure: The ferrimagnet CaBaCo4O7.50

    International Nuclear Information System (INIS)

    Pralong, V.; Caignaert, V.; Sarkar, T.; Lebedev, O.I.; Duffort, V.; Raveau, B.

    2011-01-01

    The study of the oxidation of the '114' orthorhombic cobaltite CaBaCo 4 O 7 , using first electrochemistry and then soft chemistry based on oxidation by NaClO, has allowed a new phase, CaBaCo 4 O 7.50 , to be prepared topotactically. The structural study of this phase shows that its hexagonal structure, closely related to that of orthorhombic CaBaCo 4 O 7 , is curiously similar to that of the members of the LnBaCo 4 O 7 series, in spite of its excess oxygen. Its magnetic study shows that this phase, like CaBaCo 4 O 7 , is ferrimagnetic with the same T C (60 K), but differently exhibits an unusual magnetic hysteresis. This exceptional behavior of CaBaCo 4 O 7 with respect to oxidation as well as the magnetic properties of CaBaCo 4 O 7.50 is interpreted in terms of the presence of defects due to oxidation. - Graphical Abstract: The study of the oxidation of the '114' orthorhombic cobaltite CaBaCo 4 O 7 , using first electrochemistry and then soft chemistry based on oxidation by NaClO, has allowed a new phase, CaBaCo 4 O 7.50 , to be prepared topotactically. The structural study of this phase shows that its hexagonal structure, closely related to that of orthorhombic CaBaCo 4 O 7 , is curiously similar to that of the members of the LnBaCo 4 O 7 series, in spite of its oxygen excess. Its magnetic study shows that this phase, like CaBaCo 4 O 7 , is ferrimagnetic. Highlights: → Topotactic oxidation by means of electrochemistry and soft chemistry of the '114' orthorhombic cobaltite CaBaCo 4 O 7 . → This new phase, CaBaCo 4 O 7.5 shows an hexagonal structure, is closely related to that of orthorhombic mother phase CaBaCo 4 O 7 . → CaBaCo 4 O 7.5 is ferrimagnetic and exhibits an unusual magnetic hysteresis, due to defect pinning centers.

  15. Carbon-14 immobilization via the CO2-Ba(OH)2 hydrate gas-solid reaction

    International Nuclear Information System (INIS)

    Haag, G.L.

    1980-01-01

    Although no restrictions have been placed on the release of carbon-14, it has been identified as a potential health hazard due to the ease in which it may be assimilated into the biosphere. The intent of the Carbon-14 Immobilization Program, funded through the Airborne Waste Program Management Office, is to develop and demonstrate a novel process for restricting off-gas releases of carbon-14 from various nuclear facilities. The process utilizes the CO 2 -Ba(OH) 2 hydrate gas-solid reaction to directly remove and immobilize carbon-14. The reaction product, BaCO 3 , possesses both the thermal and chemical stability desired for long-term waste disposal. The process is capable of providing decontamination factors in excess of 1000 and reactant utilization of greater than 99% in the treatment of high volumetric, airlike (330 ppM CO 2 ) gas streams. For the treatment of an air-based off-gas stream, the use of packed beds of Ba(OH) 2 .8H 2 O flakes to remove CO 2 has been demonstrated. However, the operating conditions must be maintained between certain upper and lower limits with respect to the partial pressure of water. If the water vapor pressure in the gas is less than the dissociation vapor pressure of Ba(OH) 2 .8H 2 O, the bed will deactivate. If the vapor pressure is considerably greater, pressure drop problems will increase with increasing humidity as the particles curl and degrade. Results have indicated that when operated in the proper regime, the bulk of the increase in pressure drop results from the conversion of Ba(OH) 2 .8H 2 O to BaCO 3 and not from the hydration of the commercial Ba(OH) 2 .8H 2 O (i.e. Ba(OH) 2 .7.50H 2 O) to Ba(OH) 2 .8H 2 O

  16. Optical energy gaps and photoluminescence peaks of BaGa{sub 2}S{sub 4}:Er{sup 3+} and BaGa{sub 2}Se{sub 4}:Er{sup 3+} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Sung-Hyu [Chosun University, Kwangju (Korea, Republic of); Jin, Moon-Seog [Dongshin University, Naju (Korea, Republic of); Kim, Wha-Tek [Chonnam National University, Kwangju (Korea, Republic of)

    2005-12-15

    BaGa{sub 2}S{sub 4}:Er{sup 3+} and BaGa{sub 2}Se{sub 4}:Er{sup 3+} single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the BaGa{sub 2}S{sub 4}:Er{sup 3+} and the BaGa{sub 2}Se{sub 4}:Er{sup 3+} single crystals were found to be 4.045 eV and 3.073 eV, respectively, at 11 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Sharp emission peaks were observed in the photoluminescence spectra of the single crystals and assigned to radiation recombination between split Stark levels of the Er{sup 3+} ion.

  17. The synthesis and characterization of p(nBA-DEAEMA) polymer

    Science.gov (United States)

    Jiang, X. M.; Zhu, J.; Duan, Y. Y.

    2018-01-01

    In this paper, the polymer of p (nBA-DEAEMA) was polymerized and characterized. The structure of copolymer was characterized by FT-IR and 1HNMR, and the analysis of particle size, appearance and rheology was determined too. The results showed that, the p (nBA-DEAEMA) was synthesised successful, and it could become a surface modification for the inner face of artificial trachea, after further optimization.

  18. Structural characterization of a new vacancy ordered perovskite modification found for Ba3Fe3O7F (BaFeO2.333F0.333): Towards understanding of vacancy ordering for different perovskite-type ferrites

    International Nuclear Information System (INIS)

    Clemens, Oliver

    2015-01-01

    The new vacancy ordered perovskite-type compound Ba 3 Fe 3 O 7 F (BaFeO 2.33 F 0.33 ) was prepared by topochemical low-temperature fluorination of Ba 2 Fe 2 O 5 (BaFeO 2.5 ) using stoichiometric amounts of polyvinylidene difluoride (PVDF). The vacancy order was found to be unique so far for perovskite compounds, and the connectivity pattern can be explained by the formula Ba 3 (FeX 6/2 ) (FeX 5/2 ) (FeX 3/2 X 1/1 ), with X=O/F. Mössbauer measurements were used to confirm the structural analysis and agree with the presence of Fe 3+ in the above mentioned coordination environments. Group–subgroup relationships were used to build a starting model for the structure solution and to understand the relationship to the cubic perovskite structure. Furthermore, a comparison of a variety of vacancy-ordered iron-containing perovskite-type structures is given, highlighting the factors which favour one structure type over the other depending on the composition. - Graphical abstract: The crystal structure of Ba 3 Fe 3 O 7 F in comparison to other perovskite type ferrites. - Highlights: • The crystal structure of Ba 3 Fe 3 O 7 F in comparison to other perovskite type ferrites. • Ba 3 Fe 3 O 7 F was synthesized by low temperature fluorination of Ba 2 Fe 2 O 5 . • Ba 3 Fe 3 O 7 F shows a unique vacancy order not found for other perovskite type compounds. • The structure of Ba 3 Fe 3 O 7 F was solved using group–subgroup relationships. • A systematic comparison to other ferrite type compounds reveals structural similarities and differences. • The A-site coordination of the cation is shown to play an important role for the type of vacancy order found

  19. Dielectric enhancement of BaTiO3/SrTiO3 superlattices with embedded Ni nanocrystals

    International Nuclear Information System (INIS)

    Xiong Zhengwei; Sun Weiguo; Wang Xuemin; Jiang Fan; Wu Weidong

    2012-01-01

    Highlights: ► The BaTiO 3 /SrTiO 3 superlattices with embedded Ni NCs were successfully fabricated by L-MBE. ► The influence with the various concentrations of Ni nanocrystals embedded in BaTiO 3 /SrTiO 3 superlattices was also discussed. ► The BaTiO 3 /SrTiO 3 superlattices with lower concentration of embedded Ni NCs had higher permittivity and dielectric loss compared with the pure BaTiO 3 /SrTiO 3 superlattices. ► The dielectric enhancement of BaTiO 3 /SrTiO 3 superlattices with embedded Ni NCs was proposed to explained by Drude quasi-free-electron theory. - Abstract: The self-organized Ni nanocrystals (NCs) were embedded in BaTiO 3 /SrTiO 3 superlattices using laser molecular beam epitaxy (L-MBE). The stress of the composite films was increased with the increasing concentration of embedded Ni NCs, as investigation in stress calculation. The influence with the various concentrations of Ni NCs embedded in BaTiO 3 /SrTiO 3 superlattices was also discussed. The internal stress of the films was too strong to epitaxial growth of BaTiO 3 /SrTiO 3 superlattices. Compared with the pure BaTiO 3 /SrTiO 3 superlattices, the BaTiO 3 /SrTiO 3 superlattices with lower concentration of embedded Ni NCs had higher permittivity and dielectric loss. Furthermore, the dielectric enhancement of BaTiO 3 /SrTiO 3 superlattices with embedded Ni NCs was proposed to explained by Drude quasi-free-electron theory.

  20. Impacts of Mining and Urbanization on the Qin-Ba Mountainous Environment, China

    Directory of Open Access Journals (Sweden)

    Xinliang Xu

    2016-05-01

    Full Text Available The Qin-Ba Ecological Functional Zone is a component of China’s ecological security pattern designed to protect the regional ecosystem and maintain biodiversity. However, due to the impact of mining and urban encroachment, the plight of a sustainable ecosystem in the Qin-Ba mountainous area is deteriorating. This paper has used a remote sensing and geographic information system (GIS to examine the impacts of mining and urban encroachment on the environment in the Qin-Ba mountainous area. The results indicate that the total mined area in 2013 was 22 km2 and is predicted to escalate. Results also show that the ecosystems in Fengxian County, Shaanxi Province and Baokang County, Hubei Province were most severely affected by mining. Urbanization in the Qin-Ba mountainous area has seen an increase of 85.58 km2 in urban land use from 2010 to 2013. In addition, infrastructure development including airport construction, tourism resorts and real estate development in the Qin-Ba mountainous area has intensified environmental and biodiversity disturbances since large areas of forest have been cleared. Our results should provide insight and assistance to city planners and government officials in making informed decisions.

  1. Recent progress in material technology on RE-Ba-Cu-O bulk superconductors

    International Nuclear Information System (INIS)

    Teshima, Hidekazu; Morita, Mitsuru

    2011-01-01

    The current status of large-grained RE-Ba-Cu-O (RE: Y or rare earth elements) bulk superconductors with excellent superconducting properties is described. Gd-Ba-Cu-O bulk superconductors can trap a very high magnetic field even if they are melt-processed in air. Although the electromagnetic force caused by the trapped field is larger for a larger sample and may break the sample, a large sample of Gd-Ba-Cu-O 46 mm in diameter has the potential of trapped magnetic fields greater than 10 T at around 40 K. In addition, single-grained bulk superconductors as large as 150 mm can be obtained using the RE compositional gradient method. Dy-Ba-Cu-O is an ideal material for current leads because it has low thermal conductivity and high critical current density at 77 K in high magnetic fields. Eu-Ba-Cu-O has low magnetic permeability, and is therefore suitable for bulk NMR applications. Progress in machining technology has made possible various bulk superconductors with complicated shapes such as coils, leading to small and strong electromagnets by stacking several coil-shaped bulk superconductors together. (author)

  2. Large linear magnetoresistance in a new Dirac material BaMnBi2

    International Nuclear Information System (INIS)

    Wang Yi-Yan; Yu Qiao-He; Xia Tian-Long

    2016-01-01

    Dirac semimetal is a class of materials that host Dirac fermions as emergent quasi-particles. Dirac cone-type band structure can bring interesting properties such as quantum linear magnetoresistance and large mobility in the materials. In this paper, we report the synthesis of high quality single crystals of BaMnBi 2 and investigate the transport properties of the samples. BaMnBi 2 is a metal with an antiferromagnetic transition at T N = 288 K. The temperature dependence of magnetization displays different behavior from CaMnBi 2 and SrMnBi 2 , which suggests the possible different magnetic structure of BaMnBi 2 . The Hall data reveals electron-type carriers and a mobility μ (5 K) = 1500 cm 2 /V·s. Angle-dependent magnetoresistance reveals the quasi-two-dimensional (2D) Fermi surface in BaMnBi 2 . A crossover from semiclassical MR ∼ H 2 dependence in low field to MR ∼ H dependence in high field, which is attributed to the quantum limit of Dirac fermions, has been observed in magnetoresistance. Our results indicate the existence of Dirac fermions in BaMnBi 2 . (rapid communication)

  3. Ion conductivities of ZrF4-BaF2-CsF glasses

    International Nuclear Information System (INIS)

    Kawamoto, Yoji; Nohara, Ichiro

    1987-01-01

    The glass-forming region in the ZrF 4 -BaF 2 -CsF glass system has been determined and the ac conductivity and the transport number of fluoride ions have been measured. The conductivities of compounds β-Cs 2 ZrF 6 , α-SrZrF 6 , α-BaZrF 6 , β-BaZrF 6 and α-PbZrF 6 have also been measured. These results and a previous study of ZrF 4 -BaF 2 -MF n (M: the groups I-IV metals) glasses revealed the following: (1) the ZrF 4 -BaF 2 -CsF glasses are exclusively fluoride-ion conductors; (2) the ionic conductivities of ZrF 4 -based glasses are predominantly determined by the activation energies for conduction; (3) the activation energy for conduction decreases with an increase in the average polarizability of glass-constituting cations; (4) a decrease in average Zr-F bond length and a lowering of the average F coordination number of Zr are presumed to increase the activation energy for conduction. Principles of developing ZrF 4 -based glasses with higher conductivities have also been proposed. (Auth.)

  4. Growth of single crystals of BaFe12O19 by solid state crystal growth

    Science.gov (United States)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-10-01

    Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

  5. Highlands of the upper Jequitinhonha valley, Brazil: I - characterization and classification

    Directory of Open Access Journals (Sweden)

    Fábio Henrique Alves Bispo

    2011-08-01

    Full Text Available In the upper Jequitinhonha valley, state of Minas Gerais, Brazi, there are large plane areas known as "chapadas", which are separated by areas dissected by tributaries of the Jequitinhonha and Araçuaí rivers. These dissected areas have a surface drainage system with tree, shrub, and grass vegetation, more commonly known as "veredas", i.e., palm swamps. The main purpose of this study was to characterize soil physical, chemical and morphological properties of a representative toposequence in the watershed of the Vereda Lagoa do Leandro, a swamp near Minas Novas, MG, on "chapadas", the highlands of the Alto Jequitinhonha region Different soil types are observed in the landscape: at the top - Typic Haplustox (LVA, in the middle slope - Xanthic Haplustox (LA, at the footslope - Xanthic Haplustox, gray color, here called "Gray Haplustox" ("LAC" and, at the bottom of the palm swamp - Typic Albaquult (GXbd. These soils were first morphologically described; samples of disturbed and undisturbed soils were collected from all horizons and subhorizons, to evaluate their essential physical and chemical properties, by means of standard determination of Fe, Al, Mn, Ti and Si oxides after sulfuric extraction. The contents of Fe, Al and Mn, extracted with dithionite-citrate-bicarbonate and oxalate treatments, were also determined. In the well-drained soils of the slope positions, the typical morphological, physical and chemical properties of Oxisols were found. The GXbd sample, from the bottom of the palm swamp, is grayish and has high texture gradient (B/A and massive structure. The reduction of the proportion of crystalline iron compounds and the low crystallinity along the slope confirmed the loss of iron during pedogenesis, which is reflected in the current soil color. The Si and Al contents were lowest in the "LAC" soil. There was a decrease of the Fe2O3/TiO2 ratio downhill, indicating progressive drainage restriction along the toposequence. The genesis

  6. Simulation of iron impurity in BaTiO3 crystals

    International Nuclear Information System (INIS)

    Stashans, Arvids; Castillo, Darwin

    2009-01-01

    Iron-doped barium titanate (BaTiO 3 ) has been simulated taking into account cubic and tetragonal crystallographic lattices of the crystal. A quantum-chemical method based on the Hartree-Fock formalism has been used throughout the study. The calculated equilibrium structures of Fe-doped crystals reveal the defect-inward displacements of the Ti and O atoms whereas the shifts for the Ba atoms are encountered to be away with respect to the Fe impurity. According to the analysis of electron density population and electron band structure it is found that some unusual chemical bonding might take place between the Fe atom and its six adjacent O atoms. The role of Fe impurity in the ferroelectric polarization of the tetragonal BaTiO 3 crystal has been discussed too.

  7. Synthesis and characterization of (Ba,Yb doped ceria nanopowders

    Directory of Open Access Journals (Sweden)

    Branko Matović

    2011-06-01

    Full Text Available Nanometric size (Ba, Yb doped ceria powders with fluorite-type structure were obtained by applying selfpropagating room temperature methods. Tailored composition was: Ce0.95−xBa0.05YbxO2−δ with fixed amount of Ba − 0.05 and varying Yb content “x” from 0.05 to 0.2. Powder properties such as crystallite and particle size and lattice parameters have been studied. Röntgen diffraction analyses (XRD were used to characterize the samples at room temperature. Also, high temperature treatment (up to 1550°C was used to follow stability of solid solutions. The mean diameters of the nanocrystals are determined from the full width at half maxima (FWHM of the XRD peaks. It was found that average diameter of crystallites is less than 3 nm. WilliamsonHall plots were used to separate the effect of the size and strain in the nanocrystals.

  8. Synthesis and electrical properties of BaBiO3 and high resistivity BaTiO3–BaBiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Nitish Kumar

    2016-12-01

    Full Text Available Ceramics of the composition BaBiO3 (BB were sintered in oxygen to obtain a single phase with monoclinic I2/m symmetry as suggested by high-resolution X-ray diffraction. X-ray photoelectron spectroscopy confirmed the presence of bismuth in two valence states — 3+ and 5+. Optical spectroscopy showed presence of a direct bandgap at ∼ 2.2eV and a possible indirect bandgap at ∼ 0.9eV. This combined with determination of the activation energy for conduction of 0.25eV, as obtained from ac impedance spectroscopy, suggested that a polaron-mediated conduction mechanism was prevalent in BB. The BB ceramics were crushed, mixed with BaTiO3 (BT, and sintered to obtain BT–BB solid solutions. All the ceramics had tetragonal symmetry and exhibited a normal ferroelectric-like dielectric response. Using ac impedance and optical spectroscopy, it was shown that resistivity values of BT–BB were orders of magnitude higher than BT or BB alone, indicating a change in the fundamental defect equilibrium conditions. A shift in the site occupancy of Bi to the A-site is proposed to be the mechanism for the increased electrical resistivity.

  9. Solution based approaches for the morphology control of BaTiO3 particulates

    Directory of Open Access Journals (Sweden)

    Florentina Maxim

    2010-09-01

    Full Text Available Within the action COST 539 - ELENA our contribution was aimed at studying solution based approaches for the morphology control of BaTiO3 particulates. Initially, our kinetic analysis and systematic structural and morphological studies, demonstrated that during hydrothermal synthesis from layered titanate nanotubes (TiNTS, BaTiO3 forms via two mechanisms depending on the temperature and time. At low temperatures (90°C, “wild” type BaTiO3 dendritic particles with cubic structure were formed through a phase boundary topotactic reaction. At higher temperatures and/or for longer times time, the reaction is controlled by a dissolution precipitation mechanism and “seaweed” type BaTiO3 dendrites are formed. Our results unambiguously elucidated why TiNTs do not routinely act as templates for the formation of 1D BaTiO3.In our subsequent investigations, the effect of additives on the aqueous and hydrothermal synthesis of BaTiO3 was assessed. We reported that although the tested additives influenced the growth of BaTiO3, their behaviour varied; poly(acrylic acid (PAA adsorbed on specific crystallographic faces changing the growth kinetics and inducing the oriented attachment of the particles; poly(vinyl pyrrolidone (PVP, sodium dodecylsulfate (SDS and hydroxypropylmethylcellulose (HPMC act as growth inhibitors rather than crystal habit modifiers; and DFructose appeared to increase the activation energy for nucleation, resulting in small crystals (26 nm. Our work clearly indicates that the synthesis of 1D nanostructures of complex oxides by chemical methods is non trivial.

  10. Growth of BaSi2 film on Ge(100) by vacuum evaporation and its photoresponse properties

    Science.gov (United States)

    Trinh, Cham Thi; Nakagawa, Yoshihiko; Hara, Kosuke O.; Kurokawa, Yasuyoshi; Takabe, Ryota; Suemasu, Takashi; Usami, Noritaka

    2017-05-01

    We have successfully grown a polycrystalline orthorhombic BaSi2 film on a Ge(100) substrate by an evaporation method. Deposition of an amorphous Si (a-Si) film on the Ge substrate prior to BaSi2 evaporation plays a critical role in obtaining a high-quality BaSi2 film. By controlling substrate temperature and the thickness of the a-Si film, a crack-free and single-phase polycrystalline orthorhombic BaSi2 film with a long carrier lifetime of 1.5 µs was obtained on Ge substrates. The photoresponse property of the ITO/BaSi2/Ge/Al structure was clearly observed, and photoresponsivity was found to increase with increasing substrate temperature during deposition of a-Si. Furthermore, the BaSi2 film grown on Ge showed a higher photoresponsivity than that grown on Si, indicating the potential application of evaporated BaSi2 on Ge to thin-film solar cells.

  11. Preparation and characterization of BaFe12O19/Y3Fe5O12 composites

    International Nuclear Information System (INIS)

    Lin, Ying; Kang, Pan; Yang, Haibo; Liu, Miao

    2015-01-01

    Highlights: • BaM/YIG composites were fabricated by microwave sintering method. • A simple sol–gel method was used to synthesize BaM/YIG composite powders. • The BaM phase and YIG phase are well exchange coupled in the composites. • The (BH) max can be much enhanced by the introduction of YIG. - Abstract: BaFe 12 O 19 /Y 3 Fe 5 O 12 (BaM/YIG) composites with giant enhancement of magnetic energy product ((BH) max ) were fabricated by microwave sintering the BaM/YIG composite powders, which were firstly prepared using a simple sol–gel method. The phase composition and surface morphology of the as-synthesized composites were characterized by an X-ray diffractometer and a scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, respectively. The magnetic properties of the composites were investigated by a vibrating sample magnetometer. All the composites show single-phase-like magnetic hysteresis loops. The results reveal the hard phase (BaM) and soft phase (YIG) are well exchange coupled and the introduction of YIG could significantly enhance the remnant magnetization (M r ), coercivity (H c ) and (BH) max of BaM

  12. Floristic survey of the herbaceous-shrub layer of a gallery forest in Alto Paraíso de Goiás - GO, Brazil

    Directory of Open Access Journals (Sweden)

    Eduardo Chaves

    2012-10-01

    Full Text Available Flowering species of the herbaceous and shrubby layer were sampled in a gallery forest at Portal da Chapada, Alto Paraíso de Goiás-GO in the Chapada dos Veadeiros during 12 months growing within 4.5 meters on either side of a raised pathway 2.4 Km long. The collections were included to University of Brasilia Herbarium (UB. A total of 138 species (103 genera and 40 families were recorded; the most species-rich families were Asteraceae (22, Poaceae (14, Rubiaceae (12, Fabaceae (11 and Melastomataceae (7. The richest family in number of genera was Asteraceae (19, followed by Poaceae (8, Fabaceae (8 and Rubiaceae (7. The results showed a meaningful increase in the Chapada dos Veadeiros flora, especially considering the herbaceous-shrubby layer of the gallery forests (223.6%. Despite the richness of the flora, the number of endemics species in the Goiás State was only 1.5%.

  13. Barium isotope fractionation during experimental formation of the double carbonate BaMn[CO3](2) at ambient temperature.

    Science.gov (United States)

    Böttcher, Michael E; Geprägs, Patrizia; Neubert, Nadja; von Allmen, Katja; Pretet, Chloé; Samankassou, Elias; Nägler, Thomas F

    2012-09-01

    In this study, we present the first experimental results for stable barium (Ba) isotope ((137)Ba/(134)Ba) fractionation during low-temperature formation of the anhydrous double carbonate BaMn[CO(3)](2). This investigation is part of an ongoing work on Ba fractionation in the natural barium cycle. Precipitation at a temperature of 21±1°C leads to an enrichment of the lighter Ba isotope described by an enrichment factor of-0.11±0.06‰ in the double carbonate than in an aqueous barium-manganese(II) chloride/sodium bicarbonate solution, which is within the range of previous reports for synthetic pure BaCO (3) (witherite) formation.

  14. Dosimetry of ultraviolet radiation with BaHfO{sub 3} powders; Dosimetria de radiacion ultravioleta con polvos de BaHfO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Barrera A, A. A.; Aguilar D, G. A.; Guzman M, J.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Ciudad de Mexico (Mexico); Ceron R, V., E-mail: abalba1@hotmail.com [Universidad de Guanajuato, 37670 Leon, Guanajuato (Mexico)

    2016-10-15

    Ceramic materials based on pure barium hafnate (BaHfO{sub 3}) have been obtained as a powder by the co-precipitation method. The powders obtained have a cubic structure that favors the thermoluminescent and optical properties, through which a better detection of the non-ionizing radiation is allowed. With these powders various tests were performed in the ultraviolet range at different exposure times. These thermoluminescent (Tl) studies were carried out using a Tl 3500 hand held reader which yielded a brightness curve that ranged from room temperature to the 350 degrees Celsius. This BaHfO{sub 3} response exhibits a broad brightness curve with a single peak centered around 225 degrees Celsius. Finally, is reported that there are materials of barium hafnate (BaHfO{sub 3}) doped with some rare earths (Eu, Tb) which, instead of improving the performance of the powders, decrease it, so that the use of intrinsic barium hafnate is the most appropriate. (Author)

  15. Improvement of the performance of microwave X band absorbers based on pure and doped Ba-hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Seyyed Afghahi, Seyyed Salman [Department of Materials Science and Engineering, Imam Hossein University, Tehran (Iran, Islamic Republic of); Jafarian, Mojtaba, E-mail: m.jafarian@srbiau.ac.ir [Young Researchers and Elite Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Salehi, Mohsen [Young Researchers and Elite Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Atassi, Yomen [Department of Applied Physics, Higher Institute for Applied Sciences and Technology, Damascus (Syrian Arab Republic)

    2017-01-01

    Optimum Fe/Ba mole ratio is determined in doped Ba-hexaferrite prepared via mechanical activation. X-ray diffractometer (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and vector network analyzer are used to analyze phases, structures, electromagnetic and microwave absorption properties. The mole ratio of Fe/Ba=10 is detected to be optimum for doping and synthesizing the Ba-hexaferrite. In order to achieve high absorption in X band the ions of Zr{sup 4+}–Sn{sup 4+}–Ti{sup 4+}–M{sup 2+} (M=Mg{sup 2+}, Zn{sup 2+}, Cu{sup 2+}, Co{sup 2+}) are used as dopants. The results indicate the formation of single phase Ba-hexaferrite in either pure or doped compounds without any non-magnetic intermediate phases and with spherical and hexagonal morphologies respectively for the pure and doped ferrite. It is found out that BaCo{sub 2}Zr(SnTi){sub 0.5}Fe{sub 8}O{sub 19} compound has the maximum saturation magnetization (49.80 emu/g). Also the composite of BaCo{sub 2}Zr(SnTi){sub 0.5}Fe{sub 8}O{sub 19} 50 wt% in epoxy resin exhibits a minimum reflection loss of −29 dB at 12.2 GHz with 2.6 GHz bandwidth. - Highlights: • Optimum Fe/Ba mole ratio is determined in doped Ba-hexaferrite. • Formation of a single phase M-hexaferrite, pure or doped when Fe/Ba=10. • Preparation of microwave absorber of BaCo{sub 2}Zr(SnTi){sub 0.5}Fe{sub 8}O{sub 19}/epoxy resin, 50 wt%. • The absorber exhibits a minimum RL of −29 dB at 12.2 GHz with 2.6 GHz bandwidth.

  16. Conduction Mechanisms in Multiferroic Multilayer BaTiO3/NiFe2O4/BaTiO3 Memristors

    Science.gov (United States)

    Samardzic, N.; Bajac, B.; Srdic, V. V.; Stojanovic, G. M.

    2017-10-01

    Memristive devices and materials are extensively studied as they offer diverse properties and applications in digital, analog and bio-inspired circuits. In this paper, we present an important class of memristors, multiferroic memristors, which are composed of multiferroic multilayer BaTiO3/NiFe2O4/BaTiO3 thin films, fabricated by a spin-coating deposition technique on platinized Si wafers. This cost-effective device shows symmetric and reproducible current-voltage characteristics for the actuating voltage amplitude of ±10 V. The origin of the conduction mechanism was investigated by measuring the electrical response in different voltage and temperature conditions. The results indicate the existence of two mechanisms: thermionic emission and Fowler-Nordheim tunnelling, which alternate with actuating voltage amplitude and operating temperature.

  17. BACTERICIDAL COATINGS ON TEXTILES FOR REMEDIATION OF INTERMICROBE ACTIVITY (BaCTeRIA) SUMMARY REPORT

    Science.gov (United States)

    2017-07-07

    TEXTILES FOR REMEDIATION OF INTERMICROBE ACTIVITY (BaCTeRIA) SUMMARY REPORT by Tobyn A. Branck Courtney M. Cowell Jennifer M. Rego and...October 2011 – September 2015 4. TITLE AND SUBTITLE BACTERICIDAL COATINGS ON TEXTILES FOR REMEDIATION OF INTERMICROBE ACTIVITY (BaCTeRIA) SUMMARY REPORT... REMEDIATION OF INTERMICROBE ACTIVITY (BaCTeRIA) SUMMARY REPORT Introduction The Biological Sciences and Technology Team (BSTT), Warfighter

  18. Two steps hydrothermal growth and characterisations of BaTiO3 films composed of nanowires

    Science.gov (United States)

    Zawawi, Che Zaheerah Najeehah Che Mohd; Salleh, Shahril; Oon Jew, Lee; Tufail Chaudhary, Kashif; Helmi, Mohamad; Safwan Aziz, Muhammad; Haider, Zuhaib; Ali, Jalil

    2018-05-01

    Barium titanate (BaTiO3) films composed of nanowires have gained considerable research interest due to their lead-free composition and strong energy conversion efficiency. BaTiO3 films can be developed with a simple two steps hydrothermal reactions, which are low cost effective. In this research, BaTiO3 films were fabricated on titanium foil through two steps hydrothermal method namely, the growth of TiO2 and followed by BaTiO3 films. The structural evolutions and the dielectric properties of the films were investigated as well. The structural evolutions of titanium dioxide (TiO2) and BaTiO3 nanowires were characterized using X-ray diffraction and scanning electron microscopy. First step of hydrothermal reaction, TiO2 nanowires were prepared in varied temperatures of 160 °C, 200 °C and 250 °C respectively. Second step of hydrothermal reaction was performed to produce a layer of BaTiO3 films.

  19. Growth and self-assembly of BaTiO3 nanocubes for resistive switching memory cells

    International Nuclear Information System (INIS)

    Chu, Dewei; Lin, Xi; Younis, Adnan; Li, Chang Ming; Dang, Feng; Li, Sean

    2014-01-01

    In this work, the self-assembled BaTiO 3 nanocubes based resistive switching memory capacitors are fabricated with hydrothermal and drop-coating approaches. The device exhibits excellent bipolar resistance switching characteristics with ON/OFF ratio of 58–70, better reliability and stability over various polycrystalline BaTiO 3 nanostructures. It is believed that the inter cube junctions is responsible for such a switching behaviour and it can be described by the filament model. The effect of film thickness on switching ratio (ON/OFF) was also investigated in details. - Graphical abstract: This work describes a novel resistive switching memory cell based on self-assembled BaTiO 3 nanocubes. - Highlights: • BaTiO 3 nanocubes were prepared by one step facile hydrothermal method. • Self-assembled BaTiO 3 nanocubes thin films were obtained by drop-coating approach. • The BaTiO 3 nanocubes show excellent resistive switching properties for memory applications

  20. Investigation on microstructure and dielectric behaviour of (Ba0· 999 ...

    Indian Academy of Sciences (India)

    Ceramics of BaTiO3 co-doped with Gd and Cr at Ba-site was synthesized via solid-state reaction route. Surface morphology shows the increase in grain size with the increase of Cr-content below 3 mol%. The high value of in the synthesized samples is associated with space charge polarization and inhomogeneous ...

  1. Searches for low-mass Higgs and dark bosons at BaBar

    Energy Technology Data Exchange (ETDEWEB)

    Oberhof, Benjamin, E-mail: benjamin.oberhof@pi.infn.it [INFN sezione di Pisa and Universitá di Pisa, Polo Fibonacci - Edificio C, Largo B. Pontecorvo 3, 56125 - Pisa (Italy)

    2013-01-15

    We present BaBar latest results for the direct search of a light CP-odd Higgs boson using radiative decays of the ϒ(nS) (n=1,2,3) resonances in different final states. We also present the results for the search of a hidden sector gauge and Higgs bosons using the full BaBar datasample.

  2. Particle morphology as a control of permeation in polymer films obtained from MMA/nBA colloidal dispersions.

    Science.gov (United States)

    Lestage, David J; Urban, Marek W

    2004-07-20

    The combination of precision-controlled weight loss measurements and spectroscopic surface FT-IR analysis allowed us to identify unique behaviors of poly(methyl methacrylate) (p-MMA). When MMA and n-butyl acrylate (nBA) are polymerized into p-MMA and p-nBA homopolymer blends, MMA/nBA random copolymers, and p-MMA/p-nBA core-shell morphologies, a controlled mobility and stratification of low molecular weight components occurs in films formed from coalesced colloidal dispersions. Due to different affinities toward water, p-MMA and p-nBA are capable of releasing water at different rates, depending upon particle morphological features of initial dispersions. As coalescence progresses, water molecules are released from the high free volume p-nBA particles, whereas p-MMA retains water molecules for the longest time due to its hydrophilic nature. As a result, water losses at extended coalescence times are relatively small for p-MMA. MMA/nBA copolymer and p-MMA/p-nBA blends follow the same trends, although the magnitudes of changes are not as pronounced. The p-MMA/p-nBA core-shell behavior resembles that of p-nBA homopolymer, which is attributed to significantly lower content of the p-MMA component in particles. Annealing of coalesced colloidal films at elevated temperatures causes migration of SDOSS to the F-A interface, but for films containing primarily p-nBA, reverse diffusion back into the bulk is observed. These studies illustrate that the combination of different particle morphologies and temperatures leads to controllable permeation processes through polymeric films. Copyright 2004 American Chemical Society

  3. Fabrication of Ba-K-Bi-O thick film artefacts with improved critical currents

    International Nuclear Information System (INIS)

    Moore, J.C.; Salter, C.J.; Jenkins, R.J.; Grovenor, C.R.M.; Jones, H.

    1993-01-01

    The Ba-K-Bi-O system has a maximum T c of around 30K for a composition of Ba 0.6 K 0.4 BiO 3 . Fabrication of good quality single phase samples is extremely difficult and requires careful control of the fabrication conditions. Successful synthesis procedures for Ba-K-Bi-O powder and melt cast material which allow some control of the potassium content of the product were established by Hinks et al. The process is based on a melt and sinter step in an inert atmosphere which creates oxygen vacancies and allows potassium to enter the lattice. The oxygen vacancies are then filled by a subsequent oxygen anneal to obtain superconductivity. Ba-K-Bi-O is, therefore, metastable and consequently difficult to synthesise. There have been few reports of transport measurements and even fewer reports of transport critical currents for bulk material. It is often accepted that Ba-K-Bi-O has an intrinsically low critical current, and extremely poor critical current densities of 0.05 Acm -2 have been quoted for melt cast material. It has been suggested that the presence of weak links is the cause. However, there has been little research into the relationship between process conditions and superconducting properties for melt processed Ba-K-Bi-O to confirm this. (orig.)

  4. Mapping the involvement of BA 4a and 4p during Motor Imagery.

    Science.gov (United States)

    Sharma, Nikhil; Jones, P S; Carpenter, T A; Baron, Jean-Claude

    2008-05-15

    Motor Imagery (MI) is an attractive but intriguing means to access the motor network. There are marked inconsistencies in the functional imaging literature regarding the degree, extent and distribution of the primary motor cortex (BA 4) involvement during MI as compared to Executed Movement (EM), which may in part be related to the diverse role of BA 4 and its two subdivisions (i.e., 4a and 4p) in motor processes as well as to methodological issues. Here we used fMRI with monitoring of compliance to show that in healthy volunteers optimally screened for their ability to perform MI the contralateral BA 4 is involved during MI of a finger opposition sequence (2, 3, 4, 5; paced at 1 Hz), albeit less than during EM of the same sequence, and in a location sparing the hand area. Furthermore, both 4a and 4p subdivisions were found to be involved in MI, but the relative involvement of BA 4p appeared more robust and closer to that seen with EM. We suggest that during MI the role of BA 4 and its subdivisions may be non-executive, perhaps related to spatial encoding, though clearly further studies are needed. Finally, we report a similar hemispheric activation balance within BA 4 with both tasks, which extends the commonalities between EM and MI.

  5. Nucleation control and inhibition of BaTiO3 films using hydrothermal-electrochemical method

    International Nuclear Information System (INIS)

    Escobar, Ivan; Silva, Carmen; Silva, Eric; Vargas, Tomas; Fuenzalida, Victor

    1999-01-01

    The microstructure of BaTiO 3 films on titanium by the hydrothermal-electrochemical method was investigated using a three electrode high pressure electrochemical cell in a 0.2 M Ba(OH) 2 electrolyte at 150 0 C. The spontaneous initial linked to pure hydrothermal BaTiO 3 formation can be inhibited by cathodically protecting titanium electrode since its immersion in the electrolyte. The application of initial nucleation pulses of varying the cathodic potentials affected the grain size of the deposit. It is suggested that the formation of a titanium oxide layers is a necessary step previous to the nucleation of BaTiO 3

  6. Pulsed laser deposition of Tl-Ca-Ba-Cu-O films

    International Nuclear Information System (INIS)

    Ianno, N.J.; Liou, S.H.; Woollam, J.A.; Thompson, D.; Johs, B.

    1990-01-01

    Pulsed laser deposition is a technique commonly used to deposit high quality thin films of high temperature superconductors. This paper discusses the results obtained when this technique is applied to the deposition of Tl-Ca-Ba-Cu-O thin films using a frequency doubled Nd:YAG laser operating at 532 nm and an excimer laser operating at 248 nm. Films with onset temperatures of 125 K and zero resistance temperatures of 110 K deposited on (100) oriented MgO from a composite Tl2Ca2Ba2Cu3Ox target were obtained at both wavelengths upon appropriate post deposition annealing. Films deposited at 532 nm exhibit a rough surface, while those deposited at 248 nm are smooth and homogeneous. Upon annealing, films deposited at both wavelengths are single phase Tl2Ca2Ba2Cu3Ox. 12 refs

  7. Accurate projected augmented wave datasets for BaFe2As2

    International Nuclear Information System (INIS)

    Cao Chao; Wu Yuing; Hamdan, Rashid; Wang, Yunpeng; Cheng Haiping

    2010-01-01

    By carefully choosing parameters and including more semi-core orbitals as valence electrons, we have constructed a high-quality projected augmented wave dataset that yields results comparable to existing full-potential linearized augmented plane-wave calculations. The dataset was then applied to BaFe 2 As 2 to study the effects of different levels of structure optimization, as well as different choices of exchange-correlation functionals. It was found that the local density approximation exchange-correlation functional fails to find the correct spin-density-wave anti-ferromagnetic (SDW-AFM) ground state under full optimization, while the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional obtains the correct state but significantly overestimates the magnetism. The electronic structure of the SDW-AFM state is not very sensitive to structure optimizations with the PBE exchange-correlation functional because the positions of the As atoms are preserved under optimizations. We further investigated the Ba atom diffusion process on the BaFe 2 As 2 surface using the nudged elastic bands method. The Ba atom was found to be stable above the center of the squares formed by the surface As atoms, and a diffusion barrier of 1.2 eV was found. Our simulated scanning tunneling microscopy image suggests an ordered surface Ba atom structure, in agreement with Massee et al (2009 Phys. Rev. B 80 140507; van Heumen E et al 2010 arXiv:1009.3493v1).

  8. The Danish Microbiology Database (MiBa) 2010 to 2013.

    Science.gov (United States)

    Voldstedlund, M; Haarh, M; Mølbak, K

    2014-01-09

    The Danish Microbiology Database (MiBa) is a national database that receives copies of reports from all Danish departments of clinical microbiology. The database was launched in order to provide healthcare personnel with nationwide access to microbiology reports and to enable real-time surveillance of communicable diseases and microorganisms. The establishment and management of MiBa has been a collaborative process among stakeholders, and the present paper summarises lessons learned from this nationwide endeavour which may be relevant to similar projects in the rapidly changing landscape of health informatics.

  9. Preparation, photoluminescent properties and luminescent dynamics of BaAlF5:Eu2+ nanophosphors

    International Nuclear Information System (INIS)

    Zhang, Wei; Hua, Ruinian; Liu, Tianqing; Zhao, Jun; Na, Liyan; Chen, Baojiu

    2014-01-01

    Graphical abstract: Rice-shaped BaAlF 5 :Eu 2+ nanophosphors were synthesized via one-pot hydrothermal process. The as-prepared BaAlF 5 :Eu 2+ are composed of many particles with an average diameter of 40 nm. When excited at 260 nm, the sharp line emission located at 361 nm of Eu 2+ was observed. The optimum doping concentration of Eu 2+ was confirmed to be 5 mol%. The strong ultraviolet emission of Eu 2+ ions in BaAlF 5 :Eu 2+ nanoparticles suggests that these nanoparticles may have potential applications for sensing, solid-state lasers and spectrometer calibration. - Highlights: • BaAlF 5 :Eu 2+ nanophosphors were synthesized via a mild hydrothermal process. • The Van and Huang models were used to research the mechanism of concentration quenching. • The optimum doping concentration of Eu2+ was confirmed to be 5 mol%. - Abstract: Eu 2+ -doped BaAlF 5 nanophosphors were synthesized via a facile one-pot hydrothermal method. The final products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. XRD results showed that the prepared samples are single-phase. The FE-SEM and TEM images indicated that the prepared BaAlF 5 :Eu 2+ nanophosphors are composed of many rice-shaped particles with an average diameter of 40 nm. When excited at 260 nm, BaAlF 5 :Eu 2+ nanophosphors exhibit the sharp line emissions of Eu 2+ at room temperature. The optimum doping concentration of Eu 2+ was confirmed to be 5 mol%. The Van and Huang models were used to study the mechanism of concentration quenching and the electric dipole–dipole interaction between Eu 2+ can be deduced to be a dominant for quenching fluorescence in BaAlF 5 :Eu 2+ nanophosphors. The strong ultraviolet emission of Eu 2+ in BaAlF 5 :Eu 2+ nanophosphors suggests that these nanoparticles may have potential applications for sensing, spectrometer calibration and solid-state lasers

  10. Sequential structural and antiferromagnetic transitions in BaFe2Se3 under pressure

    Science.gov (United States)

    Zhang, Yang; Lin, Ling-Fang; Zhang, Jun-Jie; Dagotto, Elbio; Dong, Shuai

    2018-01-01

    The discovery of superconductivity in the two-leg ladder compound BaFe2S3 has established the 123-type iron chalcogenides as a novel and interesting subgroup of the iron-based superconductor family. However, in this 123 series, BaFe2Se3 is an exceptional member, with a magnetic order and crystalline structure different from all others. Recently, an exciting experiment reported the emergence of superconductivity in BaFe2Se3 at high pressure [J. Ying et al., Phys. Rev. B 95, 241109(R) (2017), 10.1103/PhysRevB.95.241109]. In this paper, we report a first-principles study of BaFe2Se3 . Our analysis unveils a variety of qualitative differences between BaFe2S3 and BaFe2Se3 , including in the latter an unexpected chain of transitions with increasing pressure. First, by gradually reducing the tilting angle of iron ladders, the crystalline structure smoothly transforms from P n m a to C m c m at ˜6 GPa. Second, the system becomes metallic at 10.4 GPa. Third, its unique ambient-pressure Block antiferromagnetic ground state is replaced by the more common stripe (so-called CX-type) antiferromagnetic order at ˜12 GPa, the same magnetic state as the 123-S ladder. This transition is found at a pressure very similar to the experimental superconducting transition. Finally, all magnetic moments vanish at 30 GPa. This reported theoretical diagram of the complete phase evolution is important because of the technical challenges to capture many physical properties in high-pressure experiments. The information obtained in our calculations suggests different characteristics for superconductivity in BaFe2Se3 and BaFe2S3 : in 123-S pairing occurs when magnetic moments vanish, while in 123-Se the transition region from Block- to CX-type magnetism appears to catalyze superconductivity. Finally, an additional superconducting dome above ˜30 GPa is expected to occur.

  11. Structures, phase transitions and microwave dielectric properties of the 6H perovskites Ba3BSb2O9, B=Mg, Ca, Sr, Ba

    International Nuclear Information System (INIS)

    Ling, Chris D.; Rowda, Budwy; Avdeev, Maxim; Pullar, Robert

    2009-01-01

    We present a complete temperature-composition phase diagram for Ba 3 BSb 2 O 9 , B=Mg, Ca, Sr, Ba, along with their electrical behavior as a function of B. These compounds have long been recognized as 6H-type perovskites, but (with the exception of B=Mg) their exact structures and properties were unknown due to their low symmetries, temperature-dependent phase transitions, and difficulties in synthesizing pure samples. The full range of possible space group symmetries is observed, from ideal hexagonal P6 3 /mmc to monoclinic C2/c to triclinic P1-bar. Direct second-order transitions between these phases are plausible according to group theory, and no evidence was seen for any further intermediate phases. The phase diagram with respect to temperature and the effective ionic radius of B is remarkably symmetrical for B=Mg, Ca, and Sr. For B=Ba, a first-order phase transition to a locally distorted phase allows a metastable hexagonal phase to persist to lower temperatures than expected before decomposing around 600 K. Electrical measurements revealed that dielectric permittivity corrected for porosity does not change significantly as a function of B and is in a good agreement with the values predicted by the Clausius-Mossotti equation. - Graphical abstract: Thermodynamic phase diagram for Ba 3 BSb 2 O 9 , B=Mg, Ca, and Sr, as a function of temperature T and effective ionic radius (IR) of the B 2+ cation

  12. Effects of Ce, La and Ba addition on the electrochemical behavior of super duplex stainless steels

    International Nuclear Information System (INIS)

    Yoo, Yun-Ha; Choi, Yoon-Seok; Kim, Jung-Gu; Park, Yong-Soo

    2010-01-01

    The effects of rare earth metal (REM: Ce, La) and Ba addition on aqueous corrosion properties of super duplex stainless steels (SDSS) were investigated by electrochemical tests and surface analyses. The results of potentiodynamic test indicated that the passive range increased by the addition of Ce, La, and Ba, indicating increased relative resistance to localized corrosion. The EIS measurements showed that the Ce-La-Ba-bearing alloys exhibited higher R ct and R p values than the Ce-La-Ba-free alloy at the passive and breakdown states. Furthermore, the additions of REMs and Ba together promoted the formation of dense chromium-enriched passive film.

  13. Nuclear sub-structure in 112–122Ba nuclei within relativistic mean field theory

    International Nuclear Information System (INIS)

    Bhuyan, M.; Patra, S.K.; Arumugam, P.; Gupta, Raj K.

    2011-01-01

    Working within the framework of relativistic mean field theory, we study for the first time the clustering structure (nuclear sub-structure) of 112–122 Ba nuclei in an axially deformed cylindrical coordinate. We calculate the individual neutrons and protons density distributions for Ba-isotopes. From the analysis of the clustering configurations in total (neutrons-plus-protons) density distributions for various shapes of both the ground and excited states, we find different sub-structures inside the Ba nuclei considered here. The important step, carried out here for the first time, is the counting of number of protons and neutrons present in the clustering region(s). 12 C is shown to constitute the cluster configuration in prolate-deformed ground-states of 112–116 Ba and oblate-deformed first excited states of 118–122 Ba nuclei. Presence of other lighter clusters such as 2 H, 3 H and nuclei in the neighborhood of N = Z, 14 N, 34–36 Cl, 36 Ar and 42 Ca are also indicated in the ground and excited states of these nuclei. Cases with no cluster configuration are shown for 112–116 Ba in their first and second excited states. All these results are of interest for the observed intermediate-mass-fragments and fusion–fission processes, and the so far unobserved evaporation residues from the decaying Ba* compound nuclei formed in heavy ion reactions. (author)

  14. Microwave-Hydrothermal Synthesis and Characterization of High-Purity Nb Doped BaTiO3 Nanocrystals

    Directory of Open Access Journals (Sweden)

    A. Khanfekr

    2014-01-01

    Full Text Available The synthesis of Nb doped BaTiO3 has been investigated under Microwave-Hydrothermal (MH conditions in the temperature of 150°C for only 2 h using C16H36O4Ti, BaH2O2.8H2O and NbCl5 as Ba, Ti and  Nb sources, respectively.  Typical experiments performed on MH processing have not yet reported for Nb doped BaTiO3.  In the MH process, the formation of high purity nano tetragonal Nb-BaTiO3 was strongly enhanced. New hydrothermal method was used instead of the previous solid state reaction for the BaTiO3±Nb2O3 system. The new method uses high pressure to create nano dimension particles in a lower time and temperature. In case of the phase evolution studies, the XRD pattern measurements and Raman spectroscopy were performed. TEM and FE-SEM images were taken for the detailed analysis of the particle size, surface and morphology.  Synthesis of Nb doped BaTiO3 with the Microwave-hydrothermal provides an advantage of fast crystallization and reduced crystal size when compared to existing methods.

  15. Apresentação Workshop Baía de Guanabara

    Directory of Open Access Journals (Sweden)

    Claudia Gutteres Vilela

    2003-01-01

    Full Text Available Ano 2003 Volume 26 - Workshop Baía de Guanabara Editor: Ismar de Souza Carvalho Coordenadora: Claudia Gutteres Vilela: Apresentação ISSN: 0101-9759 É com grande prazer que participo da edição do Anuário de 2003 do Instituto de Geociências, que inclui os trabalhos apresentados no Workshop Baía, realizado nos dias 12 e 13 de novembro de 2002, nesta instituição. O sucesso desse evento deve-se em grande parte aos trabalhos, apresentados sob a forma de palestras em mesas redondas ou painéis, por pesquisadores consagrados no Brasil e no exterior. O conteúdo dos trabalhos possui uma abrangência que se estende desde a Geologia até a Biologia, passando pela Oceanografia e Geografia, sempre com o objetivo comum de reunir dados sobre a Baía de Guanabara visando o diagnóstico ambiental. O Workshop Baía congregou diversas linhas de pesquisa desenvolvidas na Baía de Guanabara e regiões adjacentes, procurando uma integração das mesmas. Deste modo alguns trabalhos caracterizaram, em um contexto mais geral, a evolução do nível do mar na região sudeste durante o Holoceno, bem como apresentaram a neotectônica da região. Geoquímica orgânica de hidrocarbonetos e de metais pesados, sedimentologia e hidrogeologia integraram-se à distribuição de microorganismos nos sedimentos e na água, analisando diversas respostas a diferentes graus de poluição em regiões distintas. Um zoneamento ambiental ofereceu uma visão dinâmica das condições naturais e sociais do conjunto da Baía de Guanabara. A importância do workshop deve-se à busca de uma integração maior dos trabalhos acadêmicos para aplicação à gestão do desenvolvimento sustentável da Baía de Guanabara e seu entorno, que abriga a cidade do Rio de Janeiro e se constitui em uma das regiões com maior índice demográfico do Brasil. Seu impacto pode se avaliado pela presença de representantes de órgãos públicos como a SERLA, a Prefeitura de Niterói e ONGs ligadas a

  16. Emergence of the sub-THz central peak at phase transitions in artificial BaTiO3/(Ba,Sr)TiO3 superlattices

    International Nuclear Information System (INIS)

    Tikhonov, Yu.A.; Razumnaya, A.G.; Torgashev, V.I.; Zakharchenko, I.N.; Yuzyuk, Yu.I.; El Marssi, M.; Ortega, N.; Kumar, A.; Katiyar, R.S.

    2015-01-01

    A prominent central peak in the sub-THz frequency range was observed in the Raman spectra of BaTiO 3 /(Ba,Sr)TiO 3 (BT/BST) superlattice grown on (001)MgO substrate. Both soft and central mode show an anomaly around 200 K and 280 K, which can be correlated with orthorhombic to monoclinic phase transition of BST and BT, respectively. The observed temperature dependence of the central mode enabled us to explain rather broad temperature dependence of the dielectric permittivity previously observed in BT/BST superlattices. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. First-principles calculations on the four phases of BaTiO3.

    Science.gov (United States)

    Evarestov, Robert A; Bandura, Andrei V

    2012-04-30

    The calculations based on linear combination of atomic orbitals basis functions as implemented in CRYSTAL09 computer code have been performed for cubic, tetragonal, orthorhombic, and rhombohedral modifications of BaTiO(3) crystal. Structural and electronic properties as well as phonon frequencies were obtained using local density approximation, generalized gradient approximation, and hybrid exchange-correlation density functional theory (DFT) functionals for four stable phases of BaTiO(3). A comparison was made between the results of different DFT techniques. It is concluded that the hybrid PBE0 [J. P. Perdew, K. Burke, M. Ernzerhof, J. Chem. Phys. 1996, 105, 9982.] functional is able to predict correctly the structural stability and phonon properties both for cubic and ferroelectric phases of BaTiO(3). The comparative phonon symmetry analysis in BaTiO(3) four phases has been made basing on the site symmetry and irreducible representation indexes for the first time. Copyright © 2012 Wiley Periodicals, Inc.

  18. Commensurability oscillations in NdBa2Cu3Oy single crystals

    Indian Academy of Sciences (India)

    gated by angular dependent magnetization in very pure twinned and twin-free NdBa2 Cu3 Oy single ... The layered structure and the c-axis coherence length, ξc ≈ 4 ˚A, smaller than the lattice ... The high quality of both crystals is demonstrated by ... Commensurability oscillations in NdBa2Cu3Oy single crystals. 2. 3. 4. 5. 6.

  19. Limited Streamer Tubes for the BaBar Instrumented Flux Return Upgrade

    International Nuclear Information System (INIS)

    Lu, C.

    2005-01-01

    Starting from the very beginning of their operation the efficiency of the RPC chambers in the BaBar Instrumented Flux Return (IFR) has suffered serious degradation. After intensive investigation, various remediation efforts had been carried out, but without success. As a result the BaBar collaboration decided to replace the dying barrel RPC chambers about two years ago. To study the feasibility of using the Limited Streamer Tube (LST) as the replacement of RPC we carried out an R and D program that has resulted in BaBar's deciding to replace the barrel RPC's with LST's. In this report we summarize the major detector R and D results, and leave other issues of the IFR system upgrade to the future publications

  20. First-principles studies on the adsorption of molecular oxygen on Ba(110) surface

    International Nuclear Information System (INIS)

    Li, S.F.; Xue Xinlian; Li Pinglin; Li Xinjian; Jia Yu

    2006-01-01

    The adsorption of O 2 on Ba(110) surface is studied with first-principles calculations based on density functional theory. Our calculations predict that O 2 may prefer to dissociative adsorption on Ba(110) surface without obvious barrier. Also our results do not support the model of charge transfer from the surface to the molecule as a bond breaking mechanism. Instead, the increasing hybridization between O 2 orbitals and the d states of Ba(110) surface may play an important role in the dissociation adsorption

  1. Hydrothermal–galvanic couple synthesis of directionally oriented BaTiO3 thin films on TiN-coated substrates

    International Nuclear Information System (INIS)

    Yang, Chia-Jung; Tsai, Di-You; Chan, Pei-Hsuan; Wu, Chu-Tsun; Lu, Fu-Hsing

    2013-01-01

    BaTiO 3 films were synthesized on TiN-coated Si substrate below 100 °C by a hydrothermal–galvanic couple technique in barium contained alkaline solutions. X-ray diffraction and electron backscatter diffraction results show that the BaTiO 3 thin films were directionally oriented grown on the TiN/Si substrates, i.e., (111) BaTiO 3 over (111) TiN. The surface morphologies revealed that BaTiO 3 nucleated and grew over the TiN surface with a single layer. From kinetic analyses, the growth rates of BaTiO 3 films prepared by the hydrothermal–galvanic couple technique were faster than a hydrothermal method. The galvanic effects were confirmed by investigating the induced currents and energies. The galvanic currents were generated and controlled by both the dissolution of TiN and the formation of BaTiO 3 . The output electric energies increased rapidly with the reaction time and leveled off at the full coverage of BaTiO 3 . - Highlights: • Cubic BaTiO 3 films are synthesized by a hydrothermal–galvanic couple method (HT–GC). • Growth rates of BaTiO 3 films made by HT–GC are faster than a hydrothermal method. • BaTiO 3 films are directionally oriented grown on the TiN/Si substrates. • Galvanic currents are controlled by dissolution of TiN and formation of BaTiO 3

  2. Factors influencing formation of highly dispersed BaTiO3 nanospheres with uniform sizes in static hydrothermal synthesis

    International Nuclear Information System (INIS)

    Gao, Jiabing; Shi, Haiyue; Dong, Huina; Zhang, Rui; Chen, Deliang

    2015-01-01

    Highly dispersed BaTiO 3 nanospheres with uniform sizes have important applications in micro/nanoscale functional devices. To achieve well-dispersed spherical BaTiO 3 nanocrystals, we carried out as reported in this paper the systematic investigation on the factors that influence the formation of BaTiO 3 nanospheres by the static hydrothermal process, including the NaOH concentrations [NaOH], molar Ba/Ti ratios (R Ba/Ti ), hydrothermal temperatures, and durations, with an emphasis on understanding the related mechanisms. Barium nitrate and TiO 2 sols derived from tetrabutyl titanate were used as the starting materials. The as-synthesized BaTiO 3 samples were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, thermogravimetry, differential thermal analysis, and FT-IR spectra. The highly dispersed BaTiO 3 nanospheres (76 ± 13 nm) were achieved under the optimum hydrothermal conditions at 200 °C for 10 h: [NaOH] = 2.0 mol L −1 and R Ba/Ti  = 1.5. Higher NaOH concentrations, higher Ba/Ti ratios, higher hydrothermal temperatures, and longer hydrothermal durations are favorable in forming BaTiO 3 nanospheres with larger fractions of tetragonal phase and higher yields; but too long hydrothermal durations resulted in abnormal growth and reduced the uniformity in particle sizes. The possible formation mechanisms for BaTiO 3 nanocrystals under the static hydrothermal conditions were investigated

  3. Thin film hybrid Josephson junctions with Co doped Ba-122

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Stefan; Doering, Sebastian; Schmidl, Frank; Tympel, Volker; Grosse, Veit; Seidel, Paul [Friedrich-Schiller-Universitaet Jena, Institut fuer Festkoerperphysik, Helmholtzweg 5, 07743 Jena (Germany); Haindl, Silvia; Iida, Kazumasa; Kurth, Fritz; Holzapfel, Bernhard [IFW Dresden, Institut fuer Metallische Werkstoffe, Helmholtzstrasse 20, 01069 Dresden (Germany); Moench, Ingolf [IFW Dresden, Institut fuer Integrative Nanowissenschaften, Helmholtzstrasse 20, 01069 Dresden (Germany)

    2011-07-01

    Josephson junctions are a strong tool to investigate fundamental superconducting properties, such as gap behaviour, dependencies from external fields and the order parameter symmetry. Finding secure values enables the possibility of theoretical descriptions to understand the physical processes within the new iron-based superconductors. Based on Co-doped BaFe{sub 2}As{sub 2} (Ba-122) layers produced via pulsed laser deposition (PLD) on (La,Sr)(Al,Ta)O{sub 3} substrates, we manufactured superconductor-normal conductor-superconductor (S-N-S) junctions structures by using photolithography, ion beam etching as well as insulating SiO{sub 2} layers. We present working Ba-122/Au/PbIn thin film Josephson junctions with different contact areas and barrier thicknesses, their temperature dependence and response to microwave irradiation. The calculated I{sub c}R{sub N} product is in the range of a couple of microvolts.

  4. Hydrothermal growth of highly textured BaTiO3 films composed of nanowires

    International Nuclear Information System (INIS)

    Zhou Zhi; Tang Haixiong; Sodano, Henry A; Lin Yirong

    2013-01-01

    Textured barium titanate (BaTiO 3 ) films are attracting immense research interest due to their lead-free composition and excellent piezoelectric and dielectric properties. Most synthesis methods for these films require a high temperature, leading to the formation of a secondary phase and an overall decrease in the electrical properties of the ceramic. In order to alleviate these issues, a novel fabrication method is introduced by transferring oriented rutile TiO 2 nanowires to a textured BaTiO 3 film at temperatures below 160 °C. The microstructure and thickness of the fabricated BaTiO 3 films were characterized by scanning electron microscopy, and the crystal structure and degree of orientation were evaluated by x-ray diffraction patterns using the Lotgering method. It is shown that the thickness of the BaTiO 3 film can be controlled by the length of TiO 2 nanowire array template, and the degree of orientation of the textured BaTiO 3 films is highly dependent on the film thickness; the crystallographic orientation has been measured to reach up to 87%. The relative dielectric constant (ε r = 1300) and ferroelectric properties (P r = 2.7 μC cm −2 , E c = 4.0 kV mm −1 ) of the textured BaTiO 3 films were also characterized to demonstrate their potential application in sensors, random access memory, and micro-electromechanical systems. (paper)

  5. Fluorine dynamics in BaF2 superionic conductors investigated by NMR

    International Nuclear Information System (INIS)

    Gumann, Patryk

    2008-01-01

    In this work the dynamics of fluorine in solid-state electrolytes having BaF 2 -structure was investigated using three different NMR-methods: field cycling relaxometry, lineshape analysis, and static field gradient NMR. For this purpose a pure BaF 2 crystal, as well as crystals doped with trivalent impurities (LaF 3 ), were studied as a function of temperature. Using MAS NMR it was possible to identify two lines in Ba 0.9 La 0.1 F 2.1 having different chemical shift, and to refer them to the modified crystal structure. On this basis a model for the fluorine lineshape has been developed, taking into account three motional processes characterized by their correlation times. It includes jump diffusion of the fluorine ions among equivalent sites within two crystallographically distinct sublattices, and inter-lattice exchange processes. By measuring frequency and temperature-dependent spin lattice relaxation times, it was possible to gain information about fluorine dynamics on microscopic length scales. An attempt was also made to analyze the data for pure BaF 2 and low admixture concentration samples with a non-exponential correlation function. (orig.)

  6. Metrological activity determination of {sup 133}Ba by sum-peak absolute method

    Energy Technology Data Exchange (ETDEWEB)

    Silva, R.L. da; Delgado, J.U.; Poledna, R.; Santos, A.; Veras, E.V. de; Rangel, J.; Trindade, O.L. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Almeida, M.C.M. de, E-mail: marcandida@yahoo.com.br, E-mail: candida@cnen.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    The National Laboratory for Metrology of Ionizing Radiation provides gamma sources of radionuclide and standardized in activity with reduced uncertainties. Relative methods require standards to determine the sample activity while the absolute methods, as sum-peak, not. The activity is obtained directly with good accuracy and low uncertainties. {sup 133}Ba is used in research laboratories and on calibration of detectors for analysis in different work areas. Classical absolute methods do not calibrate {sup 133}Ba due to its complex decay scheme. The sum-peak method using gamma spectrometry with germanium detector standardizes {sup 133}Ba samples. Uncertainties lower than 1% to activity results were obtained.

  7. Chemical correlations in Caetite (BA) region, Brazil

    International Nuclear Information System (INIS)

    Gennari, R.F.; Almeida, Geangela M.; Souza, S.O.

    2013-01-01

    Brazil's economic situation is responsible for an urgent demand for energy. There are several ways to generate energy, in some localities of our country, energy generation occurs almost exclusively by nuclear route, as in Rio de Janeiro state. Brazil has the sixth largest reserve of the uranium ore in the world. Nowadays there is only one mine under exploration (Uraniferous District of Lagoa Real - Caetite-BA). Unfortunately, nuclear power generation is better known, by common citizen, more for its unwanted effects than for its benefits. This fact is also powered by some Non-Governmental Organizations (NGOs), such as Greenpeace, who claim the uranium mine is dangerous since it causes environmental contamination. However, Industrias Nucleares do Brasil (INB) rejected these accusations. In a previous study, we demonstrated that doses of the Caetite (BA) population are consistent with those usually found in other countries. We stated also the higher concentration of 238 U determined, in only one water sample, is probably due to natural processes, as soil leaching. In order to verify the existing natural processes, macro and micro chemical elements present in water and soil samples collected in the Caetite (BA) region were determined by ICP-MS. The results were transformed into dendrograms where chemical correlations are evidenced and they are consistent with existing natural chemical processes. It was also possible to observe a correlation between samples corroborating with the Geographic Information Systems data to be presented in this same scientific event. (author)

  8. Chemical correlations in Caetite (BA) region, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Gennari, R.F., E-mail: rgennari@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. de Fisica. Dept. de Fisica Nuclear; Campos, S.S., E-mail: simaracampos@gmail.com [Universidade Estadual do Sudoeste da Bahia (UESB), Itapetinga, BA, (Brazil); Almeida, Geangela M.; Souza, S.O., E-mail: susanasouzalalic@gmail.com [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Fisica

    2013-07-01

    Brazil's economic situation is responsible for an urgent demand for energy. There are several ways to generate energy, in some localities of our country, energy generation occurs almost exclusively by nuclear route, as in Rio de Janeiro state. Brazil has the sixth largest reserve of the uranium ore in the world. Nowadays there is only one mine under exploration (Uraniferous District of Lagoa Real - Caetite-BA). Unfortunately, nuclear power generation is better known, by common citizen, more for its unwanted effects than for its benefits. This fact is also powered by some Non-Governmental Organizations (NGOs), such as Greenpeace, who claim the uranium mine is dangerous since it causes environmental contamination. However, Industrias Nucleares do Brasil (INB) rejected these accusations. In a previous study, we demonstrated that doses of the Caetite (BA) population are consistent with those usually found in other countries. We stated also the higher concentration of {sup 238}U determined, in only one water sample, is probably due to natural processes, as soil leaching. In order to verify the existing natural processes, macro and micro chemical elements present in water and soil samples collected in the Caetite (BA) region were determined by ICP-MS. The results were transformed into dendrograms where chemical correlations are evidenced and they are consistent with existing natural chemical processes. It was also possible to observe a correlation between samples corroborating with the Geographic Information Systems data to be presented in this same scientific event. (author)

  9. Consideration of the band-gap tunability of BaSi2 by alloying with Ca or Sr based on the electronic structure calculations

    International Nuclear Information System (INIS)

    Imai, Yoji; Watanabe, Akio

    2007-01-01

    The electronic structures and total energies of BaSi 2 -SrSi 2 and BaSi 2 -CaSi 2 systems have been calculated using the first-principle pseudopotential method to clarify the band gap tunability of BaSi 2 by alloying with Sr or Ca. From an energetic consideration of the compounds where all the Ba I sites or all the Ba II sites of the BaSi 2 lattice are preferentially replaced by Sr or Ca, it is expected that the Ba I site will be preferentially replaced by Sr rather than the Ba II sites. Compounds where all the Ba II sites are replaced by Sr or all the Ba II or all the Ba I sites are replaced by Ca are energetically unfavorable compared to the undissolved system of BaSi 2 and SrSi 2 or CaSi 2 . The effect of the addition of Sr or Ca into the BaSi 2 lattice on the gap value is different depending on the replaced sites of Ba. The replacement of Ba I site by Sr will broaden the band gap of BaSi 2 , which is consistent with the observed results

  10. Improved the lithium storage capability of BaLi2Ti6O14 by electroless silver coating

    International Nuclear Information System (INIS)

    Lin, Xiaoting; Wang, Pengfei; Li, Peng; Yu, Haoxiang; Qian, Shangshu; Shui, Miao; Wang, Dongjie; Long, Nengbing; Shu, Jie

    2015-01-01

    Highlights: • BaLi 2 Ti 6 O 14 /Ag is fabricated via a facile electroless deposition. • Highly dispersed Ag nanoparticles are successively coated on BaLi 2 Ti 6 O 14 . • BaLi 2 Ti 6 O 14 /Ag is used as anode material for lithium storage. • BaLi 2 Ti 6 O 14 /Ag exhibits improved lithium storage capability. - Abstract: To form BaLi 2 Ti 6 O 14 /Ag, highly dispersed Ag nanoparticles are successfully deposited on the surface of BaLi 2 Ti 6 O 14 by a simple chemical deposition method. The morphology, quantity and size of Ag nanoparticles in BaLi 2 Ti 6 O 14 /Ag composites are significantly influenced by the Ag coating contents. Electrochemical results show that Ag nanoparticles play a positive role in reducing redox polarization and improving electrical conductivity of BaLi 2 Ti 6 O 14 during lithiation/delithiation processes. Among all the as-obtained products, 6 wt.% Ag coated BaLi 2 Ti 6 O 14 shows the highest initial charge specific capacity of 160 mAh g −1 at the current density of 100 mA g −1 (1C), which is much higher than the 149.1 mAh g −1 for bare BaLi 2 Ti 6 O 14 . After 100 charge/discharge cycles, the reversible capacity can be maintained at 117.0 mAh g −1 . Moreover, this sample also shows excellent rate performance with high reversible charge capacities of 147.5, 139.7, 132.6, and 126.7 mAh g −1 at the rates of 2C, 3C, 4C and 5C, respectively. Compared with bare BaLi 2 Ti 6 O 14 , the superior electrochemical performance indicates that BaLi 2 Ti 6 O 14 /Ag can be a good anode material in lithium ion batteries.

  11. Large linear magnetoresistance in a new Dirac material BaMnBi2

    Science.gov (United States)

    Wang, Yi-Yan; Yu, Qiao-He; Xia, Tian-Long

    2016-10-01

    Dirac semimetal is a class of materials that host Dirac fermions as emergent quasi-particles. Dirac cone-type band structure can bring interesting properties such as quantum linear magnetoresistance and large mobility in the materials. In this paper, we report the synthesis of high quality single crystals of BaMnBi2 and investigate the transport properties of the samples. BaMnBi2 is a metal with an antiferromagnetic transition at T N = 288 K. The temperature dependence of magnetization displays different behavior from CaMnBi2 and SrMnBi2, which suggests the possible different magnetic structure of BaMnBi2. The Hall data reveals electron-type carriers and a mobility μ(5 K) = 1500 cm2/V·s. Angle-dependent magnetoresistance reveals the quasi-two-dimensional (2D) Fermi surface in BaMnBi2. A crossover from semiclassical MR ˜ H 2 dependence in low field to MR ˜ H dependence in high field, which is attributed to the quantum limit of Dirac fermions, has been observed in magnetoresistance. Our results indicate the existence of Dirac fermions in BaMnBi2. Project supported by the National Natural Science Foundation of China (Grant No. 11574391), the Fundamental Research Funds for the Central Universities, and the Research Funds of Renmin University of China (Grant No. 14XNLQ07).

  12. Development of BaSO sub 4 :Eu thermoluminescence phosphor

    CERN Document Server

    Madhusoodanan, U; Lakshmanan, A R

    1999-01-01

    A highly sensitive thermoluminescence (TL) phosphor based on BaSO sub 4 :Eu was developed following the coprecipitation technique and firing in argon atmosphere at 1123 K. Photoluminescence studies confirm that firing in argon atmosphere instead of air increased the incorporation of Eu ions in 2+ valence state. At low gamma-ray doses, its TL sensitivity is nearly 2 to 3 times higher than that of CaSO sub 4 :Dy phosphor. The other salient features of this BaSO sub 4 :Eu TL phosphor are a constant glow curve shape and a nearly linear gamma-ray dose response.

  13. Simulation of iron impurity in BaTiO{sub 3} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Stashans, Arvids, E-mail: arvids@utpl.edu.e [Grupo de Fisicoquimica de Materiales, Instituto de Quimica Aplicada, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Castillo, Darwin [Grupo de Fisicoquimica de Materiales, Instituto de Quimica Aplicada, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador)

    2009-05-01

    Iron-doped barium titanate (BaTiO{sub 3}) has been simulated taking into account cubic and tetragonal crystallographic lattices of the crystal. A quantum-chemical method based on the Hartree-Fock formalism has been used throughout the study. The calculated equilibrium structures of Fe-doped crystals reveal the defect-inward displacements of the Ti and O atoms whereas the shifts for the Ba atoms are encountered to be away with respect to the Fe impurity. According to the analysis of electron density population and electron band structure it is found that some unusual chemical bonding might take place between the Fe atom and its six adjacent O atoms. The role of Fe impurity in the ferroelectric polarization of the tetragonal BaTiO{sub 3} crystal has been discussed too.

  14. Glassy and Metastable Crystalline BaTi2O5 by Containerless Processing

    Science.gov (United States)

    Yoda, Shinichi; Kentei Yu, Yu; Kumar, Vijaya; Kameko, Masashi

    Many efforts have been devoted to forming bulk glass from the melt of ferroelectric crystalline materials without adding any network-forming oxides such as SiO2 due to the potential for producing transparent glass ceramics with high dielectric constant and enhanced piezoelectric, pyroelectric and electro-optic use. The containerless processing is an attractive synthesis tech-nique as it can prevent melt contamination, minimize heterogeneous nucleation, and allow melt to achieve deep undercooling for forming metastable and glassy materials. We have fabricated a new ferroelectric materiel BaTi2 O5 [1] as bulk glass from melt by us-ing containerless processing and studied the phase relationship between microstructure and ferroelectric properties of BaTi2 O5 [2]. The structures of glassy and metastable crystalline BaTi2 O5 fabricated by the containerless pro-cessing were comprehensively investigated by combined X-ray and neutron diffractions, XANES analyses and computer simulations [3]. The 3-dimensional atomic structure of glassy BaTi2 O5 (g-BaTi2 O5 ), simulated by Reverse Monte Carlo (RMC) modelling on diffraction data, shows that extremely distorted TiO5 polyhedra interconnected with both corner-and edge-shared oxy-gen, formed a higher packing density structure than that of conventional silicate glass linked with only corner-sharing of SiO4 polyhedra. In addition, XANES measurement reveales that five-coordinated TiO5 polyhedra were formable in the crystallized metastable a-and b-BaTi2 O5 phases. The structure of metastable b-BaTi2 O5 was solved by ab initio calculation, and refined by Rietveld refinement as group Pnma with unit lattices a = 10.23784 ˚, b = 3.92715 ˚, c A A = 10.92757 A ˚. Our results show that the glass-forming ability enhanced by containerless pro-cessing, not by `strong glass former', fabricated new bulk oxide glasses with peculiar structures and properties. The intermediate-range structure of g-BaTi2 O5 and the crystalline structure of

  15. Dosimetry of ultraviolet radiation with BaHfO_3 powders

    International Nuclear Information System (INIS)

    Barrera A, A. A.; Aguilar D, G. A.; Guzman M, J.; Rivera M, T.; Ceron R, V.

    2016-10-01

    Ceramic materials based on pure barium hafnate (BaHfO_3) have been obtained as a powder by the co-precipitation method. The powders obtained have a cubic structure that favors the thermoluminescent and optical properties, through which a better detection of the non-ionizing radiation is allowed. With these powders various tests were performed in the ultraviolet range at different exposure times. These thermoluminescent (Tl) studies were carried out using a Tl 3500 hand held reader which yielded a brightness curve that ranged from room temperature to the 350 degrees Celsius. This BaHfO_3 response exhibits a broad brightness curve with a single peak centered around 225 degrees Celsius. Finally, is reported that there are materials of barium hafnate (BaHfO_3) doped with some rare earths (Eu, Tb) which, instead of improving the performance of the powders, decrease it, so that the use of intrinsic barium hafnate is the most appropriate. (Author)

  16. Electronic States of IC60BA and PC71BM

    International Nuclear Information System (INIS)

    Sheng Chun-Qi; Wang Peng; Shen Ying; Li Wen-Jie; Li Hong-Nian; Zhang Wen-Hua; Zhu Jun-Fa; Lai Guo-Qiao

    2013-01-01

    We investigate the electronic states of IC 60 BA and PC 71 BM using first-principles calculations and photoelectron spectroscopy (PES) measurements. The energy level structures for all possible isomers are reported and compared with those of C 60 , C 70 and PC 61 BM. The attachment of the side chains can raise the LUMO energies and decrease the HOMO-LUMO gaps, and thus helps to increase the power-conversion efficiency of bulk heterojunction solar cells. In the PES studies, we prepared IC 60 BA and PC 71 BM films on Si:H(111) substrates to construct adsorbate/substrate interfaces describable with the integer charge-transfer (ICT) model. Successful measurements then revealed that one of the most important material properties for an electron acceptor, the energy of the negative integer charge-transfer state (E ICT− ), is 4.31 eV below the vacuum level for PC 71 BM. The E ICT− of IC 60 BA is smaller than 4.14 eV

  17. Influence of seeding on crystallization behaviour of BaNaB9 glasses

    Indian Academy of Sciences (India)

    Administrator

    Influence of seeding on crystallization behaviour of BaNaB9. O15 glasses. RAHUL VAISH and K B R VARMA*. Materials Research Centre, Indian Institute of Science, Bangalore 560 012, India. MS received 18 August 2008. Abstract. Transparent BaNaB9O15 (BNBO) glasses were fabricated via the conventional melt- ...

  18. Laser-induced fluorescence spectra of Ba+*-He exciplexes produced in cold He gas

    International Nuclear Information System (INIS)

    Fukuyama, Yoshimitsu; Matsuo, Yukari; Moriwaki, Yoshiki

    2004-01-01

    We report the observation of laser-induced fluorescence spectra of Ba +* -He exciplexes. The experiment is carried out in an environment of cold gaseous helium at a temperature range of 3-30 K. We have observed the emission spectra of exciplexes by means of excitation of the 6p 2 P 32 2 S 12 transition of Ba + ions. It is found that these spectra are redshifted from the D2 emission line in the free space and are composed of several peaks. The experimental results are reproduced well by theoretical calculation of the emission spectra for vibrational levels of Ba +* -He. We also investigate the vibrational dynamics of the 6p 2 Π 32 state of Ba + *-He, and we have determined the collision-induced vibrational relaxation cross sections of the 6p 2 Π 32 state to be 9.7±1.1 A 2 at 15 K

  19. Ab Initio Calculations for the BaTiO3 (001) Surface Structure

    Institute of Scientific and Technical Information of China (English)

    XUE Xu-Yan; WANG Chun-Lei; ZHONG Wei-Lie

    2004-01-01

    @@ The ab initio method within the local density approximation is applied to calculate cubic BaTiO3 (001) surface relaxation and rumpling for two different terminations (BaO and TiO2). Our calculations demonstrate that cubic perovskite BaTiO3 crystals possess surface polarization, accompanied by the presence of the relevant electric field.We analyse their electronic structures (band structure, density of states and the electronic density redistribution with emphasis on the covalency effects). The results are also compared with that of the previous ab initio calculations. Considerable increases of Ti-O chemical bond covalency nearby the surface have been observed.The band gap reduces especially for the TiO2 termination.

  20. Is Urgent Evoke a Digital Ba?

    DEFF Research Database (Denmark)

    Wichmand, Mette

    2018-01-01

    of such a platform, the World Bank’s online game Urgent Evoke, which has been designed with the pur- pose of engaging citizens in developing innovative solutions for sociopolitical problems like poverty. The analysis is based on Nonaka’s concept of Ba, which means “place” and is described as a platform for advancing...

  1. Metal-insulator transition and magnetic properties of La - (Ba/Ca) - Mn - O compounds

    International Nuclear Information System (INIS)

    Anbarasu, V.; Manigandan, A.; Sathiyakumar, S.; Jayabalan, K.; Kaliyaperumal, L.K.

    2009-01-01

    The manganite compounds La 2 BaMn (3+x) P y (where x = 0, 0.5 and 1) and La 2 CaMn 3 O y have been prepared for the importance in the field of magneto resistance materials through solid-state reaction technique. From the Powder XRD patterns it was confirmed that both compounds were in single phase and the refined crystal system matches with superconducting perovskite structure and the lattice parameters were calculated as a = 3.892( 6) A, b = 3.899(3) A and c = 11.619(8) A for La 2 BaMn 3 O y ; a = 3.851(3) A, b = 3.891(9) A and c = 11.542(7) A for La 2 CaMn 3 O y . The low temperature resistivity measurement reveals that the compound La 2 BaMn 3 O y exhibiting M - I transition and the transition temperature was found to be 270 K. The study on magnetization nature of the La 2 BaMn 3+x Oy (where x = 0, 0.5 and I) compounds through vibrating sample magnetometer confirms the superparamagnetic nature at room temperature condition where as La 2 CaMn 3 O y exhibits paramagnetic nature. The structural relations between the prepared manganite systems La 2 BaMn 3 O y and La 2 CaMn 3 O y with superconducting perovskite compound LaBa 2 Cu 3 O 7-y was studied with the technological application of magneto resistive property of the prepared compounds. (author)

  2. Bioaccessibility of Ba, Cu, Pb, and Zn in urban garden and orchard soils

    International Nuclear Information System (INIS)

    Cai, Meifang; McBride, Murray B.; Li, Kaiming

    2016-01-01

    Exposure of young children to toxic metals in urban environments is largely due to soil and dust ingestion. Soil particle size distribution and concentrations of toxic metals in different particle sizes are important risk factors in addition to bioaccessibility of these metals in the particles. Analysis of particle size distribution and metals concentrations for 13 soils, 12 sampled from urban gardens and 1 from orchard found that fine particles (<105 μm) comprised from 22 to 66% by weight of the tested soils, with Ba, Cu, Pb and Zn generally at higher concentrations in the finer particles. However, metal bioaccessibility was generally lower in finer particles, a trend most pronounced for Ba and Pb. Gastric was higher than gastrointestinal bioaccessibility for all metals except Cu. The lower bioaccessibility of Pb in urban garden soils compared to orchard soil is attributable to the higher organic matter content of the garden soils. - Highlights: • The bioaccessibility of metals in urban garden and orchard soils was measured. • Ba, Cu, Pb, Zn were concentrated in fine particles of the soils. • Bioaccessibilities of Ba and Pb were generally lower in fine particles of soils. • Pb bioaccessibility was generally lower in soils with higher organic matter content. • Pb bioaccessibility was lower in urban garden soils than in an orchard soil. - Pb and other trace metals (Ba, Cu, Zn) were concentrated in fine particles of urban and orchard soils, but the bioaccessibility of Ba and Pb was generally lower in finer particles.

  3. Anomalous Ba/Ca signals associated with low temperature stresses in Porites corals from Daya Bay, northern South China Sea

    Institute of Scientific and Technical Information of China (English)

    Tianran Chen; Kefu Yu; Shu Li; Tegu Chen; Qi Shi

    2011-01-01

    Barium to calcium (Ba/Ca) ratio in corals has been considered as a useful geochemical proxy for upwelling,river flood and other oceanic processes.However,recent studies indicated that additional environmental or biological factors can influence the incorporation of Ba into coral skeletons.In this study,Ba/Ca ratios of two Porites corals collected from Daya Bay,northern South China Sea were analyzed.Ba/Ca signals in the two corals were 'anomalous' in comparison with Ba behaviors seen in other near-shore corals influenced by upwelling or riverine runoff.Our Ba/Ca profiles displayed similar and remarkable patterns characterized by low and randomly fluctuating background signals periodically interrupted by sharp and large synchronous peaks,clearly indicating an environmental forcing.Further analysis indicated that the Ba/Ca profiles were not correlated with previously claimed environmental factors such as precipitation,coastal upwelling,anthropogenic activities or phytoplankton blooms in other areas.The maxima of Ba/Ca appeared to occur in the period of Sr/Ca maxima,coinciding with the winter minimum temperatures,which suggests that the anomalous high Ba/Ca signals were related to winter-time low sea surface temperature.We speculated that the Ba/Ca peaks in corals of the Daya Bay were most likely the results of enrichment of Ba-rich particles in their skeletons when coral polyps retracted under the stresses of anomalous winter low temperatures.In this case,Ba/Ca ratio in relatively high-latitude corals can be a potential proxy for tracing the low temperature stress.

  4. High spatial resolution mapping of the Cerrado's land cover and land use types in the priority area for conservation Chapada da Contagem, Brazil.

    Science.gov (United States)

    Ribeiro, F.; Roberts, D. A.; Davis, F. W.; Antunes Daldegan, G.; Nackoney, J.; Hess, L. L.

    2016-12-01

    The Brazilian savanna, Cerrado, is the second largest biome over South America and the most floristically diverse savanna in the world. This biome is considered a conservation hotspot in respect to its biodiversity importance and rapid transformation of its landscape. The Cerrado's natural vegetation has been severely transformed by agriculture and pasture activities. Currently it is the main agricultural frontier in Brazil and one of the most threatened Brazilian biomes. This scenario results in environmental impacts such as ecosystems fragmentation as well as losses in connectivity, biodiversity and gene flow, changes in the microclimate and energy, carbon and nutrients cycles, among others. The Priority Areas for Conservation is a governmental program from Brazil that identifies areas with high conservation priority. One of this program's recommendation is a natural vegetation map including their major ecosystem classes. This study aims to generate more precise information for the Cerrado's vegetation. The main objective of this study is to identify which ecosystems are being prioritized and/or threatened by land use, refining information for further protection. In order to test methods, the priority area for conservation Chapada da Contagem was selected as the study site. This area is ranked as "extremely high priority" by the government and is located in the Federal District and Goias State, Brazil. Satellites with finer spatial resolution may improve the classification of the Cerrado's vegetation. Remote sensing methods and two criteria were tested using RapidEye 3A imagery (5m spatial resolution) collected in 2014 in order to classify the Cerrado's major land cover types of this area, as well as its land use. One criterion considers the Cerrado's major terrestrial ecosystems, which are divided into forest, savanna and grassland. The other involves scaling it down to the major physiognomic groups of each ecosystem. Other sources of environmental dataset such

  5. Performances of RPCs in the BaBar Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Messner, Robert

    2003-09-26

    The BaBar experiment uses a big system based on RPC detectors to discriminate muons from pions and to identify neutral hadrons. About 2000 m{sup 2} of RPC chambers have been working at SLAC since the end of 1998. We report on the performances of the RPC chambers focusing on new problems discovered in the RPC behavior. These problems started very soon after the installation of the chambers on the detector when the high ambient temperature triggered an increase of dark currents inside the chambers and a reduction of the efficiency. Careful analysis of the BaBar data and dedicated R&D efforts in the laboratory have helped to identify the main source of the trouble in the linseed oil varnish on the bakelite electrodes.

  6. DIRC - a particle identification system for BaBar

    International Nuclear Information System (INIS)

    Hoecker, A.

    1999-10-01

    The DIRC (an acronym for Detection of Internally Reflected Cherenkov light) is a novel type of Cherenkov imaging device that has been developed, built and installed as part of the BaBar detector at the asymmetric B-factory PEP-II at SLAC. The DIRC is based on total internal reflection of Cherenkov photons produced and guided within thin, rectangular quartz bars covering the barrel region of BaBar. The photon detector is an array of photomultiplier tubes covering the photon phase space at the backward end of the bars. In its first few months of operation the DIRC performance has been found to achieve the design requirements. This note presents results from cosmic ray data and an analysis of the first beam collision runs. (author)

  7. Structural, morphological and Raman studies on hybridized PVDF/BaTiO3 nanocomposites

    Science.gov (United States)

    Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.

    2017-05-01

    Hybridized nanocomposites of polyvinylidene fluoride (PVDF) and nano - barium titanate (BaTiO3) were prepared using the solution casting method for different concentrations of nano-BaTiO3 and were characterized by X-ray diffraction and scanning electron microscopy. The flower like structure for morphology was observed in SEM. Raman analysis showed that the modified BaTiO3 particles, due to higher specific surfaces, induce, predominantly, the crystallization of the electrically active β-phase of PVDF, while the initial micron size particles induce the formation of the most common but non-polar α-crystal form.

  8. Thermoluminescence of rare earth doped BaSO/sub 4/ phosphors and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Nagpal, J.S.; Varadharajan, G. (Bhabha Atomic Research Centre, Bombay (India). Div. of Radiological Protection)

    1982-03-01

    Thermoluminescence of synthetic BaSO/sub 4/ samples individually doped with Y, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy and Tm has been studied after ..gamma..- and microwave irradiations. BaSO/sub 4/:Eu has the highest response for ..gamma..-radiation while BaSO/sub 4/:Tb exhibits highest reduction in its ..gamma..-induced TL after exposure to microwave radiation (2425 +- 25 MHz). The reduction depends on the microwave radiant exposure and is independent of the irradiance level in the range 25-200 mW . cm/sup -2/ and hence can be useful for microwave dosimetry.

  9. Inter-atomic force constants of BaF{sub 2} by diffuse neutron scattering measurement

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, Takashi, E-mail: sakuma@mx.ibaraki.ac.jp; Makhsun,; Sakai, Ryutaro [Institute of Applied Beam Science, Ibaraki University, Mito 310-8512 (Japan); Xianglian [College of Physics and Electronics Information, Inner Mongolia University for the Nationalities, Tongliao 028043 (China); Takahashi, Haruyuki [Institute of Applied Beam Science, Ibaraki University, Hitachi 316-8511 (Japan); Basar, Khairul [Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Bandung 40132 (Indonesia); Igawa, Naoki [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai 319-1195 (Japan); Danilkin, Sergey A. [Bragg Institute, Australian Nuclear Science and Technology Organisation, Kirrawee DC NSW 2232 (Australia)

    2015-04-16

    Diffuse neutron scattering measurement on BaF{sub 2} crystals was performed at 10 K and 295 K. Oscillatory form in the diffuse scattering intensity of BaF{sub 2} was observed at 295 K. The correlation effects among thermal displacements of F-F atoms were obtained from the analysis of oscillatory diffuse scattering intensity. The force constants among neighboring atoms in BaF{sub 2} were determined and compared to those in ionic crystals and semiconductors.

  10. Muon spin depolarization in Gd- and EuBa1Cu3O/sub x/

    International Nuclear Information System (INIS)

    Cooke, D.W.; Hutson, R.L.; Kwok, R.S.

    1988-01-01

    Positive muon spin rotation (μSR) measurements on Gd- and EuBa 2 Cu 3 O/sub x/ (x ∼ 7) have been conducted in the temperature interval 4-300K. For each sample, muons stop both at grain boundaries and within the superconducting grains. Measured magnetic field penetration depths are 1550 and 1900/angstrom/ for two specimens of GdBa 2 Cu 3 O/sub x/, and 1350/angstrom/ for EuBa 2 Cu 3 O/sub x/. 2 refs., 5 figs

  11. Polymorphism of tungsten perovskite compounds Ba/sub 2/SEsub(0. 67)WO/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Schittenhelm, H J; Kemmler-Sack, S [Tuebingen Univ. (F.R. Germany). Inst. fuer Anorganische Chemie

    1976-09-01

    The compounds Ba/sub 2/SEsub(0.67)WO/sub 6/ with SE = Gd-Lu are polymorphic. Above 1200/sup 0/C the instable cubic modification (ordered perovskite with 4 formula units Ba/sub 2/SEsub(0.67)vacantsub(0.33)WO/sub 6/ per cell) transforms irreversibly into a hexagonal modification with completely filled cationic lattice. For Ba/sub 2/Eusub(0.67)WO/sub 6/ the transformation is incomplete. With SE = Nd and Sm only the cubic modification is formed.

  12. Synthesis, structure, optical property, and electronic structure of Ba7AgGa5Se15

    International Nuclear Information System (INIS)

    Yin, Wenlong; He, Ran; Feng, Kai; Hao, Wenyu; Yao, Jiyong; Wu, Yicheng

    2013-01-01

    Graphical abstract: -- Highlights: •A new quaternary chalcogenide Ba 7 AgGa 5 Se 15 was synthesized. •It adopts a new structure type in the space group P31c of the trigonal system. •The structure contains a three-dimensional framework built from GaSe 4 and AgSe 4 tetrahedra. •Ba 7 AgGa 5 Se 15 is a direct semiconductor with the band gap of 2.60 (2) eV. •The electronic structure was calculated to explain the optical properties. -- Abstract: A new quaternary chalcogenide Ba 7 AgGa 5 Se 15 was synthesized by solid state reaction. It crystallizes in a new structure type in the noncentrosymmetric space group P31c of the trigonal system. In the structure, three Ga2Se 4 tetrahedra and one Ga1Se 4 tetrahedron are connected to each other by corner-sharing to form [Ga 4 Se 10 ] 8− anion clusters, which are further connected to AgSe 4 tetrahedra by corner-sharing to form a three-dimensional framework with Ba, Se7, and isolated Ga3Se 4 tetrahedra residing in the cavities. The optical band gap of 2.60 (2) eV for Ba 7 AgGa 5 Se 15 was deduced from the diffuse reflectance spectrum. From a band structure calculation, Ba 7 AgGa 5 Se 15 is a direct semiconductor and the transition between Se and Ba plays an important role in the band gap

  13. Effect of 6-BA on nodal explant bud sproutings of Coffea arabica cv. Mundo Novo Efeito de 6-BA na brotação de gemas de explantes nodais de Coffea arabica cv. Mundo Novo

    Directory of Open Access Journals (Sweden)

    Luis Carlos da Silva Ramos

    2005-01-01

    Full Text Available Coffee plants can be micropropagated by nodal bud sprouting using the 6-benzylaminopurine (6-BA hormone. However, literature reports the use of a wide range of 6-BA, from 0.5 to 88.8 µM L-1. So, this study was performed to narrow that range. Nodal explants of Coffea arabica cv Mundo Novo obtained from in vitro plantlets were inoculated on gelled-MS medium supplemented with different concentrations of 6-BA. Two assays were carried out: in the first one, 6-BA was used at concentrations of 0, 5, 25, 50, and 100 µM L-1, being evaluated at 43 and 123 days. In the second experiment, dosis of 10, 20 and 30 µM L-1, have evaluated at 65 and 100 days. Treatments with 6-BA induced multiple sprouting from the nodal explants, which were best characterized around 100 days after inoculation. The nodal explants grew taller and showed multiple shoots, whereas the effect of 6-BA at 5 to 25 µM L-1 was similar to that with higher concentrations (50 and 100 µM L-1. Nodal explants yielded from 2.9 to 6.0 buds per node, achieving height of 1.3 to 1.5 cm at 5 to 25 µM L-1 of 6-BA, whereas they yielded from 4.3 to 4.9 buds per node but the sprouting grew about 0.8 cm at 50 and 100 µM L-1 of 6-BA. This study indicated that multiple sprouting of lateral buds can be induced by lower concentrations of 6-BA, for example, from 10 to 30 µM L-1, diminishing possible risks of somaclonal variation due to high levels of hormone concentration.O cafeeiro pode ser micropropagado via brotação de gemas laterais, aplicando o regulador de crescimento 6-benzilaminopurina (6-BA. Entretanto, a literatura apresenta ampla variação da dose empregada, desde 0.5 a 88.8 µM L-1. Assim, este estudo visou otimizar doses para explantes nodais do cafeeiro C. arabica cv Mundo Novo. Explantes nodais, obtidos de plântulas cultivadas in vitro, foram inoculados em meio MS geleificado, com adição de diferentes concentrações de 6-BA. Foram feitos dois experimentos: no primeiro, 6-BA foi

  14. Heat capacity measurement of Ba3SrNb2O9

    International Nuclear Information System (INIS)

    Singh, B.M.; Samui, Pradeep; Agarwal, Renu; Mukerjee, S.K.

    2016-01-01

    Barium, Strontium and Niobium are important fission products in nuclear reactor with reasonable fission yields. During irradiation of oxide fuels, they can combine to form compounds of Ba-Sr-Nb-O system. Therefore, thermodynamic properties of Ba 3 SrNb 2 O 9 are required for modelling fuel behaviour however thermodynamic data of this compound is not available in literature. Ba 3 SrNb 2 O 9 was prepared by solid state route, by mixing stoichiometric amounts of finely grounded SrCO 3 , BaCO 3 and Nb 2 O 5 . Finally mixed powder was pressed into a pellet at 5 ton pressure for 2 minutes in a hydraulic press and the pellet was heated at 1123 K for 60 h in air. The pellet was cooled, finely grounded, re-pelletised and heated at 1473 K for 120 h. The formation of compound was confirmed by X-ray diffraction pattern, collected at room temperature using Cu-K α radiation (λ = 1.54 nm), scanned over the angular range 20-80° (2θ) with steps of 0.02°. Heat capacity of the compound was measured by the classical three-step method, in continuous mode, using LABSYS EVO, in temperature range of 370 and 950 K. No transition was observed in the investigated temperature range

  15. Physical and magnetic properties of (Ba/Sr) substituted magnesium nano ferrites

    Science.gov (United States)

    Ateia, Ebtesam E.; Takla, E.; Mohamed, Amira T.

    2017-10-01

    In the presented paper, strontium (Sr) and barium (Ba) nano ferrites were synthesized by citrate auto combustion method. The investigated samples are characterized by X-ray diffraction technique (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. The structural properties of the obtained samples were examined by XRD analysis showing that the synthesized nanoparticles are in cubic spinel structure. The average crystallite sizes are in the range of 22.66 and 21.95 nm for Mg0.7Ba0.3Fe2O4 and Mg0.7 Sr0.3Fe2O4 respectively. The VSM analysis confirms the existence of ferromagnetic nature of Sr2+/Ba2+ substituted magnesium nano particles. Exchange interaction between hard (Sr/Ba) and soft (Mg) magnetic phases improves the structural and magnetic properties of nano ferrite particles. Rigidity modulus, longitudinal and shear wave velocities are predicted theoretically from Raman spectroscopy and structural data of the investigated spinel ferrite. The magnetic and structural properties of magnesium are enhanced by doping with barium and strontium nano particles. The saturation magnetization, remanent magnetization and coercivity reported on vibrating sample magnetometer curve illustrate the promising industrial and magnetic recording applications of the prepared samples.

  16. Extended analysis of four-times ionized barium: (Ba V)

    International Nuclear Information System (INIS)

    Sharma, M.K.; Rahimullah, K.; Tauheed, A.

    2014-01-01

    The fifth spectrum of barium (Ba V) has been investigated with the aid of experimental recordings made on a 3-m normal incidence vacuum spectrograph at the Antigonish laboratory (Canada) in the wavelength region 300–2080 Å using triggered spark as an excitation source. The spectral analysis has been extended considerably to include new configuration 5s 2 5p 3 6p in even parity configuration and, 5s 2 5p 3 6d and 5s 2 5p 3 7s in odd parity configuration. Previously reported levels of the ground configuration and three lowest excited configurations 5s5p 5 , 5s 2 5p 3 5d and 5s 2 5p 3 6s in Ba V have been confirmed and all the J≥4 unknown levels of 5s 2 5p 3 5d configuration have now been established through the identification of transitions from the levels of 5s 2 5p 3 6p configuration. All the levels of 5s 2 5p 3 6p configuration and thirty seven out of forty eight levels of the 5s 2 5p 3 6d and 5s 2 5p 3 7s configurations have now been established. A configuration interaction Hartree–Fock calculation supports the analysis. -- Highlights: • The spectrum of Ba was recorded on a 3-m spectrograph with triggered spark source. • CI calculations with relativistic corrections were made for theoretical predictions. • Atomic transitions for Ba V were identified to established new energy levels. • Weighted oscillator strength (gf) and transition probabilities (gA) were calculated

  17. Computational study of Ca, Sr and Ba under pressure

    International Nuclear Information System (INIS)

    Jona, F; Marcus, P M

    2006-01-01

    A first-principles procedure for the calculation of equilibrium properties of crystals under hydrostatic pressure is applied to Ca, Sr and Ba. The procedure is based on minimizing the Gibbs free energy G (at zero temperature) with respect to the structure at a given pressure p, and hence does not require the equation of state to fix the pressure. The calculated lattice constants of Ca, Sr and Ba are shown to be generally closer to measured values than previous calculations using other procedures. In particular for Ba, where careful and extensive pressure data are available, the calculated lattice parameters fit measurements to about 1% in three different phases, both cubic and hexagonal. Rigid-lattice transition pressures between phases which come directly from the crossing of G(p) curves are not close to measured transition pressures. One reason is the need to include zero-point energy (ZPE) of vibration in G. The ZPE of cubic phases is calculated with a generalized Debye approximation and applied to Ca and Sr, where it produces significant shifts in transition pressures. An extensive tabulation is given of structural parameters and elastic constants from the literature, including both theoretical and experimental results

  18. Computational study of Ca, Sr and Ba under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Jona, F; Marcus, P M [Department of Materials Science and Engineering, State University of New York, Stony Brook, NY 11794-2275 (United States)

    2006-05-17

    A first-principles procedure for the calculation of equilibrium properties of crystals under hydrostatic pressure is applied to Ca, Sr and Ba. The procedure is based on minimizing the Gibbs free energy G (at zero temperature) with respect to the structure at a given pressure p, and hence does not require the equation of state to fix the pressure. The calculated lattice constants of Ca, Sr and Ba are shown to be generally closer to measured values than previous calculations using other procedures. In particular for Ba, where careful and extensive pressure data are available, the calculated lattice parameters fit measurements to about 1% in three different phases, both cubic and hexagonal. Rigid-lattice transition pressures between phases which come directly from the crossing of G(p) curves are not close to measured transition pressures. One reason is the need to include zero-point energy (ZPE) of vibration in G. The ZPE of cubic phases is calculated with a generalized Debye approximation and applied to Ca and Sr, where it produces significant shifts in transition pressures. An extensive tabulation is given of structural parameters and elastic constants from the literature, including both theoretical and experimental results.

  19. Cesium immobilization in (Ba,Cr)-hollandites: Effects on structure

    Science.gov (United States)

    Tumurugoti, Priyatham; Sundaram, S. K.; Misture, Scott T.

    2018-02-01

    Hollandites with compositions Ba1.15-xCs2xCr2.3Ti5.7O16 (0 ≤ x ≤ 1.15) intended for the immobilization of cesium (Cs) from nuclear waste have been prepared, characterized, and analyzed for Cs retention properties. Sol-gel synthesized powders were used for structural characterization using a combination of X-ray, neutron, and electron diffraction techniques. Phase-pure hollandites adopting tetragonal (I4/m) or monoclinic symmetry (I2/m) were observed to form in the compositional range 0 ≤ x ≤ 0.4. Structural models for the compositions, x = 0, 0.15, and 0.25 were developed from Rietveld analysis of powder diffraction data. Refined anisotropic displacement parameters (βij) for the Ba and Cs ions in the hollandite tunnels indicate local disorder of Ba/Cs along the tunnel direction. In addition, weak superlattice reflections were observed in X-ray and electron diffraction patterns that were due to the compositional modulation i.e., ordering of ions and vacancies along tunnel direction. Our overall observations suggest the phase-pure hollandites studied assumed supercell structures with ordered tunnel cations, which in turn have positional disorder in individual supercells.

  20. Colloidal synthesis of BaF2 nanoparticles and their application as fillers in polymer nanocomposites

    Science.gov (United States)

    Sathyamurthy, Srivatsan; Tuncer, Enis; More, Karren L.; Gu, Baohua; Sauers, Isidor; Paranthaman, M. Parans

    2012-03-01

    Nanoparticles of pure and Eu-doped BaF2 have been prepared through sol-gel colloidal synthesis. In addition, BaF2-filled PMMA polymer nanocomposites were fabricated and dielectric properties were measured. The as-synthesized pure and Eu-doped BaF2 nanoparticles were analyzed by both X-ray diffraction and transmission electron microscopy and consisted of crystalline BaF2 particles with an average diameter of 13.6 nm with a standard deviation of about ±2.4 nm. The photoluminescence properties of the pure and Eu-doped (2%, 4% and 8%) nanoparticles showed characteristic emission of Eu3+ (5D0→7F J ( J=1-4) transitions). We also measured significantly enhanced dielectric breakdown strength of up to 30% for BaF2 nanocomposites over the unfilled PMMA polymer. This study thus offers some promise of sol-gel synthesis of nanocomposite dielectrics with great potential for use as electrical insulation materials in cryogenic high-voltage applications.

  1. Colloidal synthesis of BaF2 nanoparticles and their application as fillers in polymer nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Sathyamurthy, Srivatsan [ORNL; Tuncer, Enis [ORNL; More, Karren Leslie [ORNL; Gu, Baohua [ORNL; Sauers, Isidor [ORNL; Paranthaman, Mariappan Parans [ORNL

    2012-01-01

    Nanoparticles of pure and Eu-doped BaF2 have been prepared through sol-gel colloidal synthesis. In addition, BaF2 filled PMMA polymer nanocomposites were fabricated and dielectric properties were measured. The as-synthesized pure and Eu-doped BaF2 nanoparticles were analyzed by both X-ray diffraction and transmission electron microscopy and consisted of crystalline BaF2 particles with an average diameter of 13.6 nm with a standard deviation of about 2.4 nm. The photoluminescence properties of the pure and Eu-doped (2%, 4% and 8%) nanoparticles showed characteristic emission of Eu3+ (5D0 7FJ (J=1-4) transitions). We also measured significantly enhanced dielectric breakdown strength of up to 30% for BaF2 nanocomposites over the unfilled PMMA polymer. This study thus offers some promise of sol-gel synthesis of nanocomposite dielectrics with great potential for use as electrical insulation materials in cryogenic high voltage applications.

  2. Surface reconstruction switching induced by tensile stress of DB steps: From Ba/Si(0 0 1)- 2 × 3 to Ba/Si(0 0 1)-4° off- 3 × 2

    Science.gov (United States)

    Kim, Hidong; Lkhagvasuren, Altaibaatar; Zhang, Rui; Seo, Jae M.

    2018-05-01

    The alkaline-earth metal adsorption on Si(0 0 1) has attracted much interest for finding a proper template in the growth of high- κ and crystalline films. Up to now on the flat Si(0 0 1) surface with double domains and single-layer steps, the adsorbed Ba atoms are known to induce the 2 × 3 structure through removing two Si dimers and adding a Ba atom per unit cell in each domain. In the present investigation, the Si(0 0 1)-4° off surface with DB steps and single domains has been employed as a substrate and the reconstruction at the initial stage of Ba adsorption has been investigated by scanning tunneling microscopy and synchrotron photoemission spectroscopy. On this vicinal and single domain terrace, a novel 3 × 2 structure rotated by 90° from the 2 × 3 structure has been found. Such a 3 × 2 structure turns out to be formed by adding a Ba atom and a Si dimer per unit cell. This results from the fact that the adsorbed Ba2+ ions with a larger ionic radius relieve tensile stress on the original Si dimers exerted by the rebonded atoms at the DB step.

  3. Stability of Tl-Ba-Ca-Cu-O Superconducting Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Siegal, M.P.; Overmyer, D.L.; Venturini, E.L.; Padilla, R.R.; Provencio, P.N.

    1999-08-23

    We report the stability of TlBa{sub 2}CaCu{sub 2}O{sub 7} (Tl-1212) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8} (T1-2212) thin films and by inference, the stability of TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 9} (Tl-1223) and Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} (Tl-2223) thin films, under a variety of conditions. In general, we observe that the stability behavior of the single Tl-O layer materials (Tl-1212 and Tl-1223)are similar and the double Tl-O layer materials (Tl-2212 and Tl-2223) are similar. All films are stable with repeated thermal cycling to cryogenic temperatures. Films are also stable in acetone and methanol. Moisture degrades film quality rapidly, especially in the form of vapor. Tl-1212 is more sensitive to vapor than Tl-2212. These materials are stable to high temperatures in either N{sub 2}, similar to vacuum for the cuprates, and O{sub 2} ambients. While total degradation of properties (superconducting and structural) occur at the same temperatures for all phases, 600 C in N{sub 2} and 700 C in O{sub 2}, the onset of degradation occurs at somewhat lower temperatures for Tl-1212 than for Tl-2212 films. In all cases, sample degradation is associated with Tl depletion from the films.

  4. Synthesis and luminescence properties of BaTiO3:RE (RE = Gd , Dy ...

    Indian Academy of Sciences (India)

    thermoluminescence (TL) properties of BaTiO3 samples doped with Gd3+, Dy3+, Tb3+ and Lu3+ were investigated. ... electron microscope using an accelerating voltage of 20 kV. .... doping of 1% mole Gd3+ ion into the BaTiO3 compound.

  5. Structural phase transition and magnetic properties of double perovskites Ba2CaMO6 (M=W, Re, Os)

    International Nuclear Information System (INIS)

    Yamamura, Kazuhiro; Wakeshima, Makoto; Hinatsu, Yukio

    2006-01-01

    Structures and magnetic properties for double perovskites Ba 2 CaMO 6 (M=W, Re, Os) were investigated. Both Ba 2 CaReO 6 and Ba 2 CaWO 6 show structural phase transitions at low temperatures. For Ba 2 CaReO 6 , the second order transition from cubic Fm3-bar m to tetragonal I4/m has been observed near 120K. For Ba 2 CaWO 6 , the space group of the crystal structure is I4/m at 295K and the transition to monoclinic I2/m has been observed between 220K. Magnetic susceptibility measurements show that Ba 2 CaReO 6 (S=1/2) and Ba 2 CaOsO 6 (S=1) transform to an antiferromagnetic state below 15.4 and 51K, respectively. Anomalies corresponding to their structural phase transition and magnetic transition have been also observed through specific heat measurements

  6. Optical properties of BaO added bioactive Na2O-CaO-P2O5 glasses

    Science.gov (United States)

    Edathazhe, Akhila B.; Shashikala, H. D.

    2018-04-01

    This paper deals with the effect of BaO addition on the optical properties of bioactive Na2O-CaO-P2O5 glasses for biomedical optics applications. The phosphate glasses with composition (26-x)Na2O-xBaO-29CaO-45P2O5 (x = 0, 5, 10, 15 mol%) have been prepared by melt-quenching technique at 1100°C. The refractive index of glasses increased with BaO content. The optical band gap and Urbach energy of synthesized glasses were derived from the optical absorption spectra by using UV-Visible spectrometer. The addition of 5 mol% of BaO increased the band gap energy of glasses due to the formation of ionic cross-links in the glass structure. The defect and interstitial bonds formation in theglasses decreased with BaO additions as indicated by reductions in the Urbach energy values. No such variations in the band gap and Urbach energy values of glasses were observed with BaO content from 5 to 15 mol%. The molar and oxide ion polarizability values were calculated from the band gap and molar volume of glasses. The increase in the calculated optical basicity and metallization criteria of glasses supported the rise in band gap energy values with BaO additions. As the melting temperature of glasses decreased from 1200 to 1100°C, the refractive index increased as supported by the measured density values. The band gap energy is not changed with melting temperature. The Urbach energy decreased with decrease in melting temperature in case of BaO-free Na2O-CaO-P2O5 glasses, whereas it increased in case of BaO added glasses due to the role of BaO as modifying oxide.

  7. Synthesis and magnetic properties of single-crystalline BaFe12O19 nanoparticles

    International Nuclear Information System (INIS)

    Yu Jiangying; Tang Shaolong; Zhai Lin; Shi Yangguang; Du Youwei

    2009-01-01

    Rod-like and platelet-like nanoparticles of simple-crystalline barium hexaferrite (BaFe 12 O 19 ) have been synthesized by the molten salt method. Both particle size and morphology change with the reaction temperature and time. The easy magnetization direction (0 0 l) of the BaFe 12 O 19 nanoparticles has been observed directly by performing X-ray diffraction on powders aligned at 0.5 T magnetic field. The magnetic properties of the BaFe 12 O 19 magnet were investigated with various sintering temperatures. The maximum values of saturation magnetization (σ s =65.8 emu/g), remanent magnetization (σ r =56 emu/g) and coercivity field (H ic =5251 Oe) of the aligned samples occurred at the sintering temperatures of 1100 deg. C. These results indicate that BaFe 12 O 19 nanoparticles synthesized by the molten salt method should enable detailed investigation of the size-dependent evolution of magnetism, microwave absorption, and realization of a nanodevice of magnetic media.

  8. Improved osteoblasts growth on osteomimetic hydroxyapatite/BaTiO_3 composites with aligned lamellar porous structure

    International Nuclear Information System (INIS)

    Liu, Beilei; Chen, Liangjian; Shao, Chunsheng; Zhang, Fuqiang; Zhou, Kechao; Cao, Jun; Zhang, Dou

    2016-01-01

    Osteoblasts growing into bone substitute is an important step of bone regeneration. This study prepared porous hydroxyapatite (HA)/BaTiO_3 piezoelectric composites with porosity of 40%, 50% and 60% by ice-templating method. Effects of HA/BaTiO_3 composites with different porosities, with and without polarizing treatment on adhesion, proliferation and differentiation of osteoblasts were investigated in vitro. Results revealed that cell densities of the porous groups were significantly higher than those of the dense group (p 0.05). The absence of mechanical loading on the polarized samples may account for this. The results indicated that hierarchically porous HA/BaTiO_3 played a favorable part in osteoblasts proliferation, differentiation and adhesion process and is a promising bone substitute material. - Graphical abstract: Aligned porous structure of HA/BaTiO_3 piezoelectric composites prepared by ice-templating method was similar to the lamellar Haversian system in bone tissue. When co-cultured with human osteosarcoma cells (MG63), porous HA/BaTiO_3 composites exhibited remarkable biological activity in promoting proliferation, differentiation and adhesion of MG63 cells. - Highlights: • The aligned porous structure of HA/BaTiO_3 composite was similar to the lamellar Haversian system in bone tissue. • The piezoelectric d_3_3 coefficient of HA/BaTiO_3 with porosity of 50% was 5.0 pC/N, much higher than that of natural bone. • HA/BaTiO_3 with porosity of 50% promoted proliferation, differentiation and adhesion of MG63 cells remarkably.

  9. Redox reactions and mechanism of luminescence in BaFCl:Eu

    CERN Document Server

    Upadeo, S V; Gundurao, T K

    1998-01-01

    The phenomenon of stimulable luminescence of phosphors pre-irradiated with high-energy radiation is widely used in the field of imaging. Phosphors such as BaFX:Eu (X = Cl, Br) are extensively used in x-ray screens for digital image processing. There is, however, divided opinion regarding the mechanism responsible for the luminescence process in these materials. In this paper we have discussed the role of Eu sup 3 sup +reversible Eu sup 2 sup + conversion in BaFCl:Eu phosphor using PL, TL, TL emission and ESR techniques. (author)

  10. Nitrogen induced ferromagnetism in Cobalt doped BaTiO3

    Directory of Open Access Journals (Sweden)

    Chandrima Mitra

    2012-09-01

    Full Text Available The electronic structure and magnetism of Cobalt doped BaTiO3 (BaTi1−xCoxO3 is investigated. Substitutional Nitrogen on an Oxygen site is found to play an important role in inducing net magnetic moments in the system. The presence of a Nitrogen atom as nearest neighbour to a Cobalt atom is crucial in producing spin splitting of both the Nitrogen and Cobalt states thereby introducing a net local magnetic moment. The introduction of Nitrogen is further found to enhance ferromagnetic interactions between Cobalt atoms.

  11. Forgotten constructions erected for mining and salt-works activities in Zlatá Baňa

    Directory of Open Access Journals (Sweden)

    Ján Brehuv

    2008-06-01

    Full Text Available Village Zlatá Baňa is known for the mining activities for gold, silver, mercury and antimony in the past. This article is devoted notto mining activities but to forgotten 2 dams, which were erected on the Delňa brook. The first was constructed above Zlatá Baňa fromwood in 1691 and does not exist presently. The second one was erected beneath Zlatá Baňa between 1802 – 1807 from stone and cementmortar. It exists up to this day but it is not working. The mentioned dams enabled to create water reservoirs. The first one enabled the water transport of wood trunksfrom Žlatá Baňa to Soľná Baňa in 1691 for a mining output of a salt-stone (or stone-salt. In the years 1807-1917, water from the second reservoir enabled the water transport of wood by a wooden flume 18,9 km long from Zlatá Baňa to the salt-works in Solivar. The mentioned dams and their water reservoirs enabled the high economical effectivity of the mining output of salt and salt-production of the salt-works in Solivar.

  12. Tl, Bi, and Pb doping in Ba4BiPb2TlO12-δ

    International Nuclear Information System (INIS)

    Sutto, T.E.; Averill, B.A.

    1992-01-01

    To determine the effects of different 6s metal concentrations on the superconducting nature of Ba 4 BiPb 2 TlO 12-δ , materials produced via four doping schemes were examined: Ba 4 Bi(Pb, Tl) 3 O 12-δ , Ba 4 -(BiPb) 3 TlO 12-δ , Ba 4 (Bi,Tl) 2 Pb 2 O 12-δ , and Ba 4 Bi x Pb 4-2x Tl x O 12-δ . For the parent compound a value of δ = 0.91 was observed, indicating that approximately 1/4 oxygen atom was missing per cubic subsection of the unit cell. For all samples, the symmetry of the parent compound changed from orthorhombic to tetragonal as the system moved away from the ideal composition. This was usually accompanied by the loss of superconductivity, which exhibited a maximum T c of 10.5 K for the parent compound Ba 4 BiPb 2 TlO 12-δ . Also reported are high-temperature magnetic susceptibility results, which are used to determine the effect of metal substitution on the density of states at the Fermi level. For each set of variants on the parent composition, the onset of superconductivity was accompanied by a significant decrease in the size of the Pauli paramagnetic signal. 16 refs., 6 figs

  13. Investigation of BaMoO4-Ln2(MoO4)3 systems (Ln = Nd, Sm, Yb)

    International Nuclear Information System (INIS)

    Vakulyuk, V.V.; Evdokimov, A.A.; Khomchenko, G.P.

    1982-01-01

    Using the methods of X-ray phase and differential-thermal analyses phase ratios in the systems BaMoO 4 -Ln 2 (MoO 4 ) 3 (Ln=Nd, Sm, Yb); BaNd 2 (MoO 4 ) 4 -MaGd 2 (MoO 4 ) are studied. Unit cell parameters and the character of melting of the compounds BaLn 2 (MoO 4 ) 4 are specified. Effect of growth conditions on laminated nature of BaGd 2 (MoO 4 ) 4 monocrystals is studied

  14. Modelo de adaptación de Roy en el baño en cama

    Directory of Open Access Journals (Sweden)

    José Manuel Flórez Ramos

    2016-09-01

    Full Text Available Objetivo: Evaluar los efectos de dos tipos de baño en cama: seco y tradicional, frente a la respuesta adaptativa en modo fisiológico de Roy en paciente crítico cardiovascular (pccv. Metodología: Estudio de diseño cuasi-experimental, de intervención con preprueba y posprueba, realizado en la Unidad de Cuidados Intensivos (uci de la Clínica Medellín. El grupo experimental fue de 36 pacientes, a quienes se les realizó baño en cama seco; el grupo control fue de 36 pacientes, a quienes se les realizó baño en cama tradicional. Se utilizaron los estadísticos Wilcoxon, u de Mann Whitney y el Modelo de dos factores, con medidas repetidas en un factor. Resultados: Se encontró un efecto benéfico durante la realización del baño en cama en seco, puesto que los indicadores de tensión arterial y frecuencia respiratoria no presentaron respuestas inefectivas (p = 0,03 y p = 0,013, respectivamente. Por otra parte, las variables duración del baño y cuidados adicionales fueron satisfactorias en comparación con el baño en cama tradicional. Conclusiones: Los resultados permiten recomendar el uso del baño en cama en seco en paciente crítico cardiovascular (pccv, en virtud de los efectos benéficos que facilitan los procesos de adaptación, contribuyendo así a cualificar el cuidado de enfermería en este tipo de pacientes.

  15. Hybrid molecular beam epitaxy for the growth of stoichiometric BaSnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, Abhinav, E-mail: praka019@umn.edu; Dewey, John; Yun, Hwanhui; Jeong, Jong Seok; Mkhoyan, K. Andre; Jalan, Bharat, E-mail: bjalan@umn.edu [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2015-11-15

    Owing to its high room-temperature electron mobility and wide bandgap, BaSnO{sub 3} has recently become of significant interest for potential room-temperature oxide electronics. A hybrid molecular beam epitaxy (MBE) approach for the growth of high-quality BaSnO{sub 3} films is developed in this work. This approach employs hexamethylditin as a chemical precursor for tin, an effusion cell for barium, and a radio frequency plasma source for oxygen. BaSnO{sub 3} films were thus grown on SrTiO{sub 3} (001) and LaAlO{sub 3} (001) substrates. Growth conditions for stoichiometric BaSnO{sub 3} were identified. Reflection high-energy electron diffraction (RHEED) intensity oscillations, characteristic of a layer-by-layer growth mode were observed. A critical thickness of ∼1 nm for strain relaxation was determined for films grown on SrTiO{sub 3} using in situ RHEED. Scanning transmission electron microscopy combined with electron energy-loss spectroscopy and energy dispersive x-ray spectroscopy confirmed the cube-on-cube epitaxy and composition. The importance of precursor chemistry is discussed in the context of the MBE growth of BaSnO{sub 3}.

  16. Template synthesis and magnetic properties of highly aligned barium hexaferrite (BaFe12O19) nanofibers

    International Nuclear Information System (INIS)

    Huang, Boneng; Li, Congju; Wang, Jiaona

    2013-01-01

    Using electrospun poly(ethylene terephthalate)/citric acid (PET/CA) microfibers as the template, highly aligned barium hexaferrite (BaFe 12 O 19 ) nanofibers with diameters of ca. 800 nm and lengths up to 2 cm were synthesized by sol–gel precursor coating technique and subsequent high temperature calcination. Structural and morphological investigations revealed that individual BaFe 12 O 19 nanofibers were composed of numerous nanocrystallites stacking alternatively along the nanofiber axis, the average grain size was ca. 225 nm and the single crystallites on each BaFe 12 O 19 nanofibers were of random orientations. The formation mechanism of aligned BaFe 12 O 19 nanofibers was proposed based on experiment. The magnetic measurement revealed that the aligned BaFe 12 O 19 nanofibers exhibited orientation-dependent magnetic behavior with respect to the applied magnetic field. The magnetic anisotropy with the easy magnetizing axis along the length of the nanofibers was due to the shape anisotropy. Such aligned magnetic nanofibers can find relevance in application requiring an orientation-dependent physical response. - Highlights: ► A simple method was used to synthesize the aligned BaFe 12 O 19 nanofibers. ► The aligned BaFe 12 O 19 nanofibers display an obvious orientation-dependent magnetic behavior. ► The method can be readily applied to other aligned one-dimensional inorganic nanomaterials

  17. One-step synthesis of single phase micro-sized BaFe12O19 hexaplates via a modified hydrothermal approach

    International Nuclear Information System (INIS)

    Cao, Liangliang; Zeng, Yanwei; Ding, Chuan; Li, Rongjie; Li, Chuanming; Zhang, Chengzhe

    2016-01-01

    Single phase BaFe 12 O 19 ferrite identified by X-ray diffraction and Raman spectroscopy has been successfully synthesized using Fe(NO 3 ) 3 ·9H 2 O and Ba(NO 3 ) 2 as starting materials and NaOH as a precipitant via a modified one-step hydrothermal approach which involves the elimination of carbonate radicals from reaction system based on the stoichiometric ratio of [Ba 2+ ]/[Fe 3+ ]. Hydrothermal products under various synthetic conditions were studied, including different addition amounts of Ba(NO 3 ) 2 in the modified operation, reaction temperatures and times, and hydroxyl concentrations. The BaFe 12 O 19 particles featuring an excellent hexagonal plates shape can be hydrothermally synthesized with the aid of polyethylene glycol. It has been found that the presence of α-Fe 2 O 3 in a traditional hydrothermal process is motivated by the deviation from the desired [Ba 2+ ]/[Fe 3+ ] ratio caused by the negligent precipitation of Ba 2+ ions to BaCO 3 . An investigation on the preferred hydrothermal product through thermodynamic calculation shows that the reduction in Gibbs free energy for the exclusive formation of BaFe 12 O 19 with 1 mol of Fe 3+ ions at 220 °C is approximately 32 kJ higher than that for the complete transformation to α-Fe 2 O 3 with an equal consumption quantity of Fe 3+ ions. - Highlights: • Pure BaFe 12 O 19 was hydrothermally synthesized based on the stoichiometric ratio. • A modified operation was employed to eliminate self-invited carbonate ions. • BaFe 12 O 19 particles feature an excellent micro-sized hexaplates shape. • BaFe 12 O 19 was thermodynamically confirmed to be preferred result instead of α-Fe 2 O 3 .

  18. Jumping the gun: Smoking constituent BaP causes premature primordial follicle activation and impairs oocyte fusibility through oxidative stress

    International Nuclear Information System (INIS)

    Sobinoff, A.P.; Pye, V.; Nixon, B.; Roman, S.D.; McLaughlin, E.A.

    2012-01-01

    Benzo(a)pyrene (BaP) is an ovotoxic constituent of cigarette smoke associated with pre-mature ovarian failure and decreased rates of conception in IVF patients. Although the overall effect of BaP on female fertility has been documented, the exact molecular mechanisms behind its ovotoxicity remain elusive. In this study we examined the effects of BaP exposure on the ovarian transcriptome, and observed the effects of in vivo exposure on oocyte dysfunction. Microarray analysis of BaP cultured neonatal ovaries revealed a complex mechanism of ovotoxicity involving a small cohort of genes associated with follicular growth, cell cycle progression, and cell death. Histomorphological and immunohistochemical analysis supported these results, with BaP exposure causing increased primordial follicle activation and developing follicle atresia in vitro and in vivo. Functional analysis of oocytes obtained from adult Swiss mice treated neonatally revealed significantly increased levels of mitochondrial ROS/lipid peroxidation, and severely reduced sperm-egg binding and fusion in both low (1.5 mg/kg/daily) and high (3 mg/kg/daily) dose treatments. Our results reveal a complex mechanism of BaP induced ovotoxicity involving developing follicle atresia and accelerated primordial follicle activation, and suggest short term neonatal BaP exposure causes mitochondrial leakage resulting in reduced oolemma fluidity and impaired fertilisation in adulthood. This study highlights BaP as a key compound which may be partially responsible for the documented effects of cigarette smoke on follicular development and sub-fertility. -- Highlights: ► BaP exposure up-regulates canonical pathways linked with follicular growth/atresia. ► BaP causes primordial follicle activation and developing follicle atresia. ► BaP causes oocyte mitochondrial ROS and lipid peroxidation, impairing fertilisation. ► Short term neonatal BaP exposure compromises adult oocyte quality.

  19. Jumping the gun: Smoking constituent BaP causes premature primordial follicle activation and impairs oocyte fusibility through oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Sobinoff, A.P.; Pye, V. [Reproductive Science Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW2308 (Australia); Nixon, B.; Roman, S.D. [Reproductive Science Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW2308 (Australia); ARC Centre of Excellence in Biotechnology and Development, University of Newcastle, Callaghan, NSW2308 (Australia); McLaughlin, E.A., E-mail: eileen.mclaughlin@newcastle.edu.au [Reproductive Science Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW2308 (Australia); ARC Centre of Excellence in Biotechnology and Development, University of Newcastle, Callaghan, NSW2308 (Australia)

    2012-04-01

    Benzo(a)pyrene (BaP) is an ovotoxic constituent of cigarette smoke associated with pre-mature ovarian failure and decreased rates of conception in IVF patients. Although the overall effect of BaP on female fertility has been documented, the exact molecular mechanisms behind its ovotoxicity remain elusive. In this study we examined the effects of BaP exposure on the ovarian transcriptome, and observed the effects of in vivo exposure on oocyte dysfunction. Microarray analysis of BaP cultured neonatal ovaries revealed a complex mechanism of ovotoxicity involving a small cohort of genes associated with follicular growth, cell cycle progression, and cell death. Histomorphological and immunohistochemical analysis supported these results, with BaP exposure causing increased primordial follicle activation and developing follicle atresia in vitro and in vivo. Functional analysis of oocytes obtained from adult Swiss mice treated neonatally revealed significantly increased levels of mitochondrial ROS/lipid peroxidation, and severely reduced sperm-egg binding and fusion in both low (1.5 mg/kg/daily) and high (3 mg/kg/daily) dose treatments. Our results reveal a complex mechanism of BaP induced ovotoxicity involving developing follicle atresia and accelerated primordial follicle activation, and suggest short term neonatal BaP exposure causes mitochondrial leakage resulting in reduced oolemma fluidity and impaired fertilisation in adulthood. This study highlights BaP as a key compound which may be partially responsible for the documented effects of cigarette smoke on follicular development and sub-fertility. -- Highlights: ► BaP exposure up-regulates canonical pathways linked with follicular growth/atresia. ► BaP causes primordial follicle activation and developing follicle atresia. ► BaP causes oocyte mitochondrial ROS and lipid peroxidation, impairing fertilisation. ► Short term neonatal BaP exposure compromises adult oocyte quality.

  20. Crystal structure and chemical bonding analysis of BaPtCd{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gulo, Fakhili [Department of Chemical Education, Sriwijaya University, Inderalaya 30662, South Sumatra (Indonesia); Koehler, Juergen [Max Planck Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany)

    2015-03-15

    The new ternary intermetallic phase, BaPtCd{sub 2}, was synthesized by solid-state reaction from direct combination of the elements in a stoichiometric mixture. The reaction was done at 850 C for 15 h, followed by an equilibration at 600 C for 4 d. The crystal structure was determined by X-ray diffraction method on a single crystal. BaPtCd{sub 2} is isotypic to MgCuAl{sub 2} and crystallizes in the orthorhombic space group Cmcm [a = 4.467(2), b = 11.143(4), c = 8.240(3) Aa, V = 410.2(3) Aa{sup 3}, and Z = 4]. Barium atoms are linked together forming zigzag chains. Cadmium atoms are bonded to each other forming six-membered rings of platinum centered boat and anti-boat conformations. BaPtCd{sub 2} contains 16 electrons per formula unit and belongs to the electron poorest compounds with MgCuAl{sub 2} type structure. Calculations based on the linear muffin-tin orbitals method in the atomic spheres approximation show that significant bonding states in BaPtCd{sub 2} are unoccupied. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Fluorine dynamics in BaF{sub 2} superionic conductors investigated by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Gumann, Patryk

    2008-07-01

    In this work the dynamics of fluorine in solid-state electrolytes having BaF{sub 2}-structure was investigated using three different NMR-methods: field cycling relaxometry, lineshape analysis, and static field gradient NMR. For this purpose a pure BaF{sub 2} crystal, as well as crystals doped with trivalent impurities (LaF{sub 3}), were studied as a function of temperature. Using MAS NMR it was possible to identify two lines in Ba{sub 0.9}La{sub 0.1}F{sub 2.1} having different chemical shift, and to refer them to the modified crystal structure. On this basis a model for the fluorine lineshape has been developed, taking into account three motional processes characterized by their correlation times. It includes jump diffusion of the fluorine ions among equivalent sites within two crystallographically distinct sublattices, and inter-lattice exchange processes. By measuring frequency and temperature-dependent spin lattice relaxation times, it was possible to gain information about fluorine dynamics on microscopic length scales. An attempt was also made to analyze the data for pure BaF{sub 2} and low admixture concentration samples with a non-exponential correlation function. (orig.)

  2. Composition changes in sputter deposition of Y-Ba-Cu-O films

    International Nuclear Information System (INIS)

    Hoshi, Y.; Naoe, M.

    1989-01-01

    The authors discuss the mechanism of the composition change in sputter deposition of Y-BA-Cu-O film from YBa 2 Cu 3 O 7-chi target investigated by means of a rf planar magnetron sputtering apparatus. Film composition changes significantly with not only substrate temperature Ts and sputtering gas pressure, but also substrate position. Lack of Cu and Ba content is significant in the film deposited at the substrate position just above the erosion area of the sputtering target. Suppression of bombardment of the substrate surface by negative ions emitted from the target and substrate is effective in increasing Cu and Ba content in the film. These results indicate not only that the sticking probability of the sputtered particles changes with Ts and incident particle energy, but also that high energy particle bombardment of the substrate surface plays an important role in the change of the film composition

  3. BaTiO3-based piezoelectrics: Fundamentals, current status, and perspectives

    Science.gov (United States)

    Acosta, M.; Novak, N.; Rojas, V.; Patel, S.; Vaish, R.; Koruza, J.; Rossetti, G. A.; Rödel, J.

    2017-12-01

    We present a critical review that encompasses the fundamentals and state-of-the-art knowledge of barium titanate-based piezoelectrics. First, the essential crystallography, thermodynamic relations, and concepts necessary to understand piezoelectricity and ferroelectricity in barium titanate are discussed. Strategies to optimize piezoelectric properties through microstructure control and chemical modification are also introduced. Thereafter, we systematically review the synthesis, microstructure, and phase diagrams of barium titanate-based piezoelectrics and provide a detailed compilation of their functional and mechanical properties. The most salient materials treated include the (Ba,Ca)(Zr,Ti)O3, (Ba,Ca)(Sn,Ti)O3, and (Ba,Ca)(Hf,Ti)O3 solid solution systems. The technological relevance of barium titanate-based piezoelectrics is also discussed and some potential market indicators are outlined. Finally, perspectives on productive lines of future research and promising areas for the applications of these materials are presented.

  4. Device characteristics of organic light-emitting diodes based on electronic structure of the Ba-doped Alq3 layer.

    Science.gov (United States)

    Lim, Jong Tae; Kim, Kyung Nam; Yeom, Geun Young

    2009-12-01

    Organic light-emitting diodes (OLEDs) with a Ba-doped tris(8-quinolinolato)aluminum(III) (Alq3) layer were fabricated to reduce the barrier height for electron injection and to improve the electron conductivity. In the OLED consisting of glass/ITO/4,4',4"-tris[2-naphthylphenyl-1-phenylamino]triphenylamine (2-TNATA, 30 nm)/4,4'-bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl (NPB, 18 nm)/Alq3 (42 nm)/Ba-doped Alq3 (20 nm, x%: x = 0, 10, 25, and 50)/Al (100 nm), the device with the Alq3 layer doped with 10% Ba showed the highest light out-coupling characteristic. However, as the Ba dopant concentration was increased from 25% to 50%, this device characteristic was largely reduced. The characteristics of these devices were interpreted on the basis of the chemical reaction between Ba and Alq3 and the electron injection property by analyzing the electronic structure of the Ba-doped Alq3 layer. At a low Ba doping of 10%, mainly the Alq3 radical anion species was formed. In addition, the barrier height for electron injection in this layer was decreased to 0.6 eV, when compared to the pristine Alq3 layer. At a high Ba doping of 50%, the Alq3 molecules were severely decomposed. When the Ba dopant concentration was changed, the light-emitting characteristics of the devices were well coincided with the formation mechanism of Alq3 radical anion and Alq3 decomposition species.

  5. Comportamiento dieléctrico de compuestos epoxi/aluminio/BaTiO3

    Directory of Open Access Journals (Sweden)

    Castro, M. S.

    2009-06-01

    Full Text Available In order to improve the dielectric behaviour of epoxi/BaTiO3, in this work the influence of micrometric aluminum metal flakes (Al, on the dielectric properties of epoxy / BaTiO3 composites was studied. Epoxy resin, Al and BaTiO3 were mixed using an ultrasonic mixer and composites were deposited onto glass substrates by dipping technique. Obtained materials presented good dielectric properties at room temperature, and relaxation process appeared due to the resin behaviour. Obtained results were compared with those reported in literature for similar systems.Con el objetivo de mejorar el comportamiento dieléctrico de los compuestos epoxi/BaTiO3, en este trabajo se estudió la influencia de partículas metálicas de aluminio (Al, con forma de escamas y tamaño micrométrico, sobre las propiedades dieléctricas de sistemas epoxi / BaTiO3. El material compuesto fue obtenido por la técnica de inmersión o “dipping”. La mezcla de los componentes fue llevado a cabo en mezclador ultrasónica y la deposición se realizó sobre sustratos de vidrio. Los materiales obtenidos presentaron buenas propiedades dieléctricas a temperatura ambiente, sin alcanzar el límite de percolación, y los fenómenos de relajación fueron generados por los dominios de la resina. Los valores obtenidos fueron comparados con los reportados en la bibliografía para sistemas similares.

  6. Ba9V3Se15: a novel compound with spin chains

    Science.gov (United States)

    Zhang, Jun; Liu, Min; Wang, Xiancheng; Zhao, Kan; Duan, Lei; Li, Wenmin; Zhao, Jianfa; Cao, Lipeng; Dai, Guangyang; Deng, Zheng; Feng, Shaomin; Zhang, Sijia; Liu, Qingqing; Yang, Yi-feng; Jin, Changqing

    2018-05-01

    In this work, a novel compound Ba9V3Se15 with one-dimensional (1D) spin chains was synthesized under high-pressure and high-temperature conditions. It was systematically characterized via structural, magnetic, thermodynamic and transport measurements. Ba9V3Se15 crystallizes into a hexagonal structure with a space group of P-6c2 (188) and the lattice constants of a  =  b  =  9.5745(7) Å and c  =  18.7814(4) Å. The crystal structure consists of face-sharing octahedral VSe6 chains along c axis, which are trimeric and arranged in a triangular lattice in ab-plane. Ba9V3Se15 is a semiconductor and undergoes complex magnetic transitions. In the zero-field-cooled (ZFC) process with magnetic field of 10 Oe, Ba9V3Se15 sequentially undergoes ferrimagnetic and spin cluster glass transition at 2.5 K and 3.3 K, respectively. When the magnetic field exceeds 50 Oe, only the ferrimagnetic transition can be observed. Above the transition temperature, the specific heat contains a significant magnetic contribution that is proportional to T 1/2. The calculation suggests that the nearest neighbor (NN) intra-chain antiferromagnetic exchange J 1 is much larger than the next nearest neighbor (NNN) intra-chain ferromagnetic exchange J 2. Therefore, Ba9V3Se15 can be regarded as an effective ferromagnetic chains with effective spin-1/2 by the formation of the V(2)(↓) V(1)(↑) V(2)(↓) cluster.

  7. Excimer laser assisted re-oxidation of BaTiO3 thin films on Ni metal foils

    International Nuclear Information System (INIS)

    Bharadwaja, S. S. N.; Ko, S. W.; Qu, W.; Clark, T.; Rajashekhar, A.; Motyka, M.; Podraza, N.; Randall, C. A.; Trolier-McKinstry, S.

    2016-01-01

    Excimer laser assisted re-oxidation for reduced, crystallized BaTiO 3 thin films on Ni-foils was investigated. It was found that the BaTiO 3 can be re-oxidized at an oxygen partial pressure of ∼50 mTorr and substrate temperature of 350 °C without forming a NiO x interface layer between the film and base metal foil. The dielectric permittivity of re-oxidized films was >1000 with loss tangent values <2% at 100 Hz, 30 mV rms excitation signal. Electron Energy Loss Spectroscopy indicated that BaTiO 3 thin films can be re-oxidized to an oxygen stoichiometry close to ∼3 (e.g., stoichiometric). High resolution cross sectional transmission electron microscopy showed no evidence of NiO x formation between the BaTiO 3 and the Ni foil upon excimer laser re-oxidation. Spectroscopic ellipsometry studies on laser re-oxidized [001] C and [111] C BaTiO 3 single crystals indicate that the re-oxidation of BaTiO 3 single crystals is augmented by photo-excitation of the ozone, as well as laser pulse induced temperature and local stress gradients

  8. Improvement of BaO:B2O3:Fly ash glasses: Radiation shielding, physical and optical properties

    International Nuclear Information System (INIS)

    Tuscharoen, S.; Kaewkhao, J.; Limkitjaroenporn, P.; Limsuwan, P.; Chewpraditkul, W.

    2012-01-01

    Highlights: ► BaO:B 2 O 3 :Fly ash glasses have been improved in radiation Shielding, physical and optical properties. ► The visible light transmission of RHA glass was better than SiO 2 . ► At all BaO concentrations, exhibited the better half values layer in comparison window and ordinary concrete. -- Abstract: Rice husk ash glass (RHA-glass) of composition xBaO:(80 − x)B 2 O 3 :20RHA where x = 45, 50, 55, 60, 65 and 70 wt.% have been prepared using melt-quenching method and investigated on their optical, physical and gamma-rays shielding properties. The densities of these glass samples were increased with increasing of BaO content, due to higher molecular weight of BaO comparing with B 2 O 3 . The molar volume of these glasses was increased with increasing content of BaO; BaO acts as modifier to increase the loose packing. The visible light transmission of RHA glass was better than SiO 2 glass prepared in same formula and preparing condition. The experimental values of gamma ray shielding properties such as; mass attenuation coefficients, atomic cross sections and effective atomic numbers, were found in good agreement with the theoretical values as calculated from WinXCom. Moreover the glass system at all BaO concentrations, exhibited the better half values layer in comparison window and ordinary concrete.

  9. Tuning the nonlinear optical absorption in Au/BaTiO3 nanocomposites with gold nanoparticle concentration

    Science.gov (United States)

    Bijeesh, M. M.; Shakhi, P. K.; Varier, Geetha K.; Nandakumar, P.

    2018-06-01

    We report on the nonlinear optical absorption coefficient of Au/BaTiO3 nanocomposite films and its dependence on gold nanoparticle concentration. Au/BaTiO3 nanocomposite films with different molar ratio of Au/Ba are prepared by sol-gel technique and characterized by X-ray diffraction, UV Visible absorption spectroscopy and high resolution transmission electron microscopy. An open aperture Z-scan technique is employed to study the third order nonlinear optical properties of Au/BaTiO3 thin films. An Nd:YAG laser operating at 532 nm wavelength having a pulse width of 5 ns is used for the measurements. The two-photon absorption coefficient of the films increases linearly with gold nanoparticle concentration and significant enhancement of nonlinear optical absorption is observed. This ability to fine tune the nonlinear optical coefficients of Au/BaTiO3 films would be handy in optical device applications.

  10. Cariri pluviosity and aquifers: regulating agent of the social and economic development

    International Nuclear Information System (INIS)

    Santiago, Maria Marlucia Freitas; Frischkorn, Horst; Serejo, Alfredo Nelson Cabral; Studart, Ticiana; Mendes Filho, Josue

    1992-01-01

    Hydraulic measures and tracing techniques shows a reply time from the Chapada do Araripe aquifer, to the pluvial water infiltration, in six months, coinciding with the dry season. Tritium and 14 C natural tracing measures and the conductivity at the Cariri basin indicate a quick reply to the direct infiltration by the recent water presence and old water contribution originated from the Chapada. It concludes that the economy and the social welfare are dependents of the underground water reserves and the climate through the precipitation regime, regulates and promote the social and economic development of the region

  11. Diversidade genÃtica da abelha sem ferrÃo melipona quinquefasciata baseada no sequÃnciamento das regiÃes its1 e 18s do dna ribossÃmico nuclear

    OpenAIRE

    JÃlio OtÃvio Portela Pereira

    2006-01-01

    A pesquisa foi desenvolvida no perÃodo de janeiro de 2003 a marÃo de 2006, nos Departamentos de Zootecnia, e Biologia da Universidade Federal do CearÃ, localizada no municÃpio de Fortaleza, estado do CearÃ. As amostras de abelhas foram coletadas nos estados do CearÃ, Piauà e GoiÃs. O objetivo desta tese foi estudar a diversidade genÃtica de populaÃÃes da abelha sem ferrÃo Melipona quinquefasciata, ocorrendo naturalmente na Chapada do Araripe (Sul do CearÃ), na Chapada da Ibiapaba (Oeste do Ce...

  12. Consequences of Ca multisite occupation for the conducting properties of BaTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zulueta, Y.A., E-mail: yohandysalexis.zuluetaleyva@student.kuleuven.be [Departamento de Física, Facultad de Ciencias Naturales, Universidad de Oriente, CP-90500 Santiago de Cuba (Cuba); Department of Chemistry, KU Leuven, B-3001 Leuven (Belgium); Dawson, J.A. [Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Leyet, Y. [Departamento de Engenharia de Materiais, Universidade Federal do Amazonas, Av. General Rodrigo Otávio, 6200 – Coroado I, 69077-000 Manaus (Brazil); Departamento de Física, Universidade Federal do Amazonas, Av. General Rodrigo Otávio, 6200 – Coroado I, 69077-000 Manaus, Amazonas (Brazil); Anglada-Rivera, J. [Instituto Federal de Educação Ciência e Tecnologia do Amazonas, Av. 7de Setembro, 1975, 69020-120 Manaus (Brazil); Guerrero, F. [Departamento de Física, Universidade Federal do Amazonas, Av. General Rodrigo Otávio, 6200 – Coroado I, 69077-000 Manaus, Amazonas (Brazil); Silva, R.S. [Departamento de Física, Universidade Federal de Sergipe, 49100-000 São Cristóvão, SE (Brazil); Nguyen, Minh Tho [Department of Chemistry, KU Leuven, B-3001 Leuven (Belgium)

    2016-11-15

    In combination with the dielectric modulus formalism and theoretical calculations, a newly developed defect incorporation mode, which is a combination of the standard A- and B-site doping mechanisms, is used to explain the conducting properties in 5 mol% Ca-doped BaTiO{sub 3}. Simulation results for Ca solution energies in the BaTiO{sub 3} lattice show that the new oxygen vacancy inducing mixed mode exhibits low defect energies. A reduction in dc conductivity compared with undoped BaTiO{sub 3} is witnessed for the incorporation of Ca. The conducting properties of 5 mol% Ca-doped BaTiO{sub 3} are analyzed using molecular dynamics and impedance spectroscopy. The ionic conductivity activation energies for each incorporation mode are calculated and good agreement with experimental data for oxygen migration is observed. The likely existence of the proposed defect configuration is also analyzed on the basis of these methods. - Graphical abstract: Oxygen vacancy formation as a result of self-compensation in Ca-doped BaTiO{sub 3}.

  13. Ba-DOPED ZnO MATERIALS: A DFT SIMULATION TO INVESTIGATE THE DOPING EFFECT ON FERROELECTRICITY

    Directory of Open Access Journals (Sweden)

    Luis H. da S. Lacerda

    2016-04-01

    Full Text Available ZnO is a semiconductor material largely employed in the development of several electronic and optical devices due to its unique electronic, optical, piezo-, ferroelectric and structural properties. This study evaluates the properties of Ba-doped wurtzite-ZnO using quantum mechanical simulations based on the Density Functional Theory (DFT allied to hybrid functional B3LYP. The Ba-doping caused increase in lattice parameters and slight distortions at the unit cell angle in a wurtzite structure. In addition, the doping process presented decrease in the band-gap (Eg at low percentages suggesting band-gap engineering. For low doping amounts, the wavelength characteristic was observed in the visible range; whereas, for middle and high doping amounts, the wavelength belongs to the Ultraviolet range. The Ba atoms also influence the ferroelectric property, which is improved linearly with the doping amount, except for doping at 100% or wurtzite-BaO. The ferroelectric results indicate the ZnO:Ba is an strong option to replace perovskite materials in ferroelectric and flash-type memory devices.

  14. Crazy for Ya Ba: methamphetamine use among northern Thai youth.

    Science.gov (United States)

    Cohen, Anjalee

    2014-07-01

    Since the mid-1990s, Thailand has been one of the largest per capita consumers of methamphetamine pills (ya ba - "crazy drug") in the world and one of the leading consumers of methamphetamine in Southeast Asia, with its youth comprising the majority of users. This article examines the socio-cultural context of methamphetamine use among young Thai in order to understand its widespread appeal. The study is based on 18 months of ethnographic research in Chiang Mai, northern Thailand, between 2002 and 2006 and a follow-up field trip in 2011. In-depth interviews were carried out with 211 young people aged between 15 and 25 in institutional and non-institutional settings. Many of the findings derive from participant observation and informal interviews with a small sample of 20 people. Chiang Mai youth have transformed methamphetamine from a labourers' drug centred on economic utility to a multi-purpose youth drug primarily consumed for pleasure and performance. Ya ba appeals to many young Thai due to its positive image as a modern and fashionable consumer commodity, with confidence in these synthetic pills drawing on and mirroring a broader faith in modern (western) medicine. The growing demand for ya ba in northern Thailand is in part a reflection of the changing social values that have accompanied rapid urbanisation and modernisation in Thailand. In their overwhelming aspiration to be modern, young Thai are consuming ya ba not to rebel against the dominant culture, but to keep up with the demands and expectations of a modern capitalist society. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Ba-rich sanidine megacrysts in trachytic rocks of Eslamy volcano, NW Iran

    Science.gov (United States)

    Aßbichler, Donjá; Asadpour, Manijeh; Heuss-Aßbichler, Soraya; Kunzmann, Thomas

    2016-04-01

    The Eslamy volcano is located on a peninsula at the eastern coast of Urumieh lake, NW Iran. The complex stratovolcano with gentle slope flanks exposes a collapsed caldera in the central part. Specific features are different sanidine rich rocks that occur in form of ejecta and flows. According to the field observations they are products of one volcanic event. XRF measurements show they all have trachytic compositions. Typical for this locality are the large sanidine phenocrysts. In the trachytic flow the sanidine crystals reach average size of ~4 cm embedded in a greenish-blue matrix consisting mainly of crystallized feldspar and subordinate pyroxen. Occasionally feldspar megacrysts of approx. 10 cm were observed. Na content of the sanidine megacrysts varies between 0.05 - 0.5 pfu with higher concentrations in the cores. Furthermore they show oscillatory zoning patterns caused by variations of Ba content (0-0.04 pfu). The matrix of the trachytic flow consist mainly of interlocking sanidine crystals (0.05-0.45 pfu Na) partly with Ba-rich cores containing up to 0.06 pfu Ba. In contrast to the megacrysts they show slightly higher Fe contents (0.025-0.035 pfu). The volcanic ejecta with bombs of approx. 50 cm in size were found in one distinct layer within a pyroclastic horizon. The average diameter of the feldspar phenocrysts is much smaller (0.5-2 cm). Sanidine is the main phase of these rocks (up to 80 %). As mafic phase up to 30 % pyroxen (mainly diospide) ± biotite can be observed. Accessories are magnetite ± apatite ± titanite ± zircon. In contrast to the flow rocks the main phase of the matrix of the ejecta is always glass with higher Fe2O3 (total) contents (up to 6 wt.-%) indicating a fast cooling of the sample due to ejection. They are completely depleted in Ba. In two samples zoned feldspar relicts enclosed in glass show remolten rims. Similar to flow rocks the feldspar phenocrysts of all ejecta show a complex zoning pattern, e.g. three samples expose high

  16. Electrical conductivity and chemical stability of BaCe0· 8− xAxGd0 ...

    Indian Academy of Sciences (India)

    ... K. BaCe0.7In0.1Gd0.2O3− and BaCe0.7Zr0.1Gd0.2O3− ceramics exhibit an excellent chemical stability against boiling water. Indium is a suitable doping element to promote the sintering densification and to enhance both electrical conductivity and chemical stability of Gd-doped BaCeO3 at operating temperatures.

  17. Electrical Conduction of Ba(Ti0.99Fe0.01)O3-δ Ceramic at High Temperatures

    Science.gov (United States)

    Yu, Zi-De; Chen, Xiao-Ming

    2018-03-01

    BaTiO3 and Ba(Ti0.99Fe0.01)O3-δ ceramics with dense microstructure have been synthesized by a solid-state reaction method, and their electrical conduction investigated by broadband electrical impedance spectroscopy at frequencies from 0.05 Hz to 3 × 106 Hz and temperatures from 200°C to 400°C. Compared with BaTiO3, the real part of the permittivity and the phase-transition temperature of Ba(Ti0.99Fe0.01)O3-δ decreased. Relaxation peaks appeared in the curves of the imaginary part of the permittivity as a function of frequency. With increase in frequency, the peaks gradually shifted towards higher frequency and their height increased. Conductivity was closely related to frequency and temperature. Frequency-dependent conductivity was analyzed using the Jonscher double power law. Compared with BaTO3, Ba(Ti0.99Fe0.01)O3-δ exhibited high impedance at given frequency and temperature. Impedance Cole-Cole plots displayed two semicircles, which could be well fit using two parallel RC equivalent circuit models. The conductivity activation energy was found to be around 1 eV. For Ba(Ti0.99Fe0.01)O3-δ , the electrical modulus curve versus frequency displayed two peaks.

  18. Nanocrystals of a new complex perovskite dielectric Ba{sub 2}TmSbO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Nair, V.M. [Department of Physics, University College, Trivandrum 695034, Kerala (India); Jose, R., E-mail: rjose@ump.edu.my [Faculty of Industrial Sciences and Technology, Universiti Malaysia Pahang, 26300 Kuantan (Malaysia); Anil Kumar, G.M. [Noritake Co Ltd, 300 Higashiyama, Miyoshi, Aichi 470-0293 (Japan); Yusoff, Mashitah M. [Faculty of Industrial Sciences and Technology, Universiti Malaysia Pahang, 26300 Kuantan (Malaysia); Wariar, P.R.S. [Department of Physics, University College, Trivandrum 695034, Kerala (India)

    2012-01-25

    Highlights: Black-Right-Pointing-Pointer A new material, Ba{sub 2}TmSbO{sub 6}, has been synthesized as nanocrystals for the first time. Black-Right-Pointing-Pointer A combustion process, characterized by a one-pot procedure, was adopted to synthesize Ba{sub 2}TmSbO{sub 6} as nanocrystals. Black-Right-Pointing-Pointer Crystal structure and dielectric properties of the Ba{sub 2}TmSbO{sub 6} have been studied and compared with similar materials. - Abstract: Nanocrystals of a new complex perovskites ceramic oxide, barium thulium antimony oxide - Ba{sub 2}TmSbO{sub 6}, were synthesized using a single step auto-ignition combustion process. The combustion product was single phase and composed of aggregates of nanocrystals of sizes in the range 20-50 nm. Ba{sub 2}TmSbO{sub 6} crystallized in cubic perovskite structure with lattice parameter, a = 8.4101 Angstrom-Sign . The polycrystalline fluffy combustion product was sintered to high density ({approx}97%) at {approx}1450 Degree-Sign C for 4 h. Resistivity of the sintered specimen was {approx}5 M{Omega}/cm. The Ba{sub 2}TmSbO{sub 6} has dielectric constant ({epsilon} Prime ) and dielectric loss (tan {delta}) of 17 and {approx}10{sup -4} at 5 MHz; the new material would probably be developed as a low-loss dielectric material.

  19. Magnetic order and crystal fields in the Pnma phases of Tm2BaTO5(T=Co and Ni)

    International Nuclear Information System (INIS)

    Harker, S.J.; Stewart, G.A.

    2000-01-01

    The magnetic ordering and crystal field interactions of the Pnma phases of both Tm 2 BaCoO 5 and Tm 2 BaNiO 5 are investigated by 169 Tm Moessbauer spectroscopy and the temperature-dependent hyperfine interactions are compared with those obtained elsewhere for Tm 2 BaCuO 5 . The Pnma phases are shown to order magnetically at temperatures of 3.5(2) K (Tm 2 BaCoO 5 ) and 4.85(5) K (Tm 2 BaNiO 5 ), the order being induced by the transition metal. For Tm 2 BaNiO 5 an additional first-order transition observed at T≤1.4 K is identified with the independent magnetic order of the thulium sub-lattice. (orig.)

  20. Ultrasonic Investigations on Polonides of Ba, Ca, and Pb

    Science.gov (United States)

    Singh, Devraj; Bhalla, Vyoma; Bala, Jyoti; Wadhwa, Shikha

    2017-10-01

    The temperature-dependent mechanical and ultrasonic properties of barium, calcium, and lead polonides (BaPo, CaPo, and PbPo) were investigated in the temperature range 100-300 K. The second- and third-order elastic constants (SOECs and TOECs) were computed using Coulomb and Born-Mayer potential and these in turn have been used to estimate other secondary elastic properties such as strength, anisotropy, microhardness, etc. The theoretical approach followed the prediction that BaPo, CaPo, and PbPo are brittle in nature. PbPo is found to be the hardest amongst the chosen compounds. Further the SOECs and TOECs are applied to determine ultrasonic velocities, Debye temperature, and acoustic coupling constants along , , and orientations at room temperature. Additionally thermal conductivity has been computed using Morelli and Slack's approach along different crystallographic directions at room temperature. Finally ultrasonic attenuation due to phonon-phonon interaction and thermoelastic relaxation mechanisms has been computed for BaPo, CaPo, and PbPo. The behaviour of these compounds is similar to that of semi-metals with thermal relaxation time of the order 10-11 s. The present computation study is reasonably in agreement with the available theoretical data for the similar type of materials.

  1. Stoichiometric analysis of Y-Ba-Cu-O superconductors using deuterons

    International Nuclear Information System (INIS)

    Tang, S.M.; Ong, T.H.; Tan, M.G.; Loh, K.K.; Sow, C.H.; Yuan, B.; Orlic, I.

    1993-01-01

    In principle, deuteron irradiation can be used for a complete stoichiometric analysis of Y-Ba-Cu-O superconductors. The contents of all the four chemical constituents can be determined by simultaneous detection of the 0.871 MeV prompt gamma rays from the 16 O(d, pγ) 17 O * reaction and of the characteristic X-rays produced by DIXE (deuteron induced X-ray emission). In this paper we present the approach taken and the results obtained in exploring the applicability of this technique for accurate quantitative determinations of the chemical constituents of bulk Y-Ba-Cu-O superconductors. (orig.)

  2. Operation manual of microbeam system in Takasaki for biological application (MiST-BA)

    International Nuclear Information System (INIS)

    Sakashita, Tetsuya; Yokota, Yuichiro; Wada, Seiichi; Funayama, Tomoo; Kobayashi, Yasuhiko

    2004-03-01

    Microbeam System is a powerful tool for micro-radiosurgery studies and direct investigation of cell-to-cell communications such as 'bystander effects'. Microbeam system in Takasaki for biological application (MiST-BA) has been developed for several years and applied to some cases. There were fate mapping of the cellular blastoderm stage egg of the silkworm and bystander effects such as inhibition of cell proliferation, induction of micronuclei, and so on. The aim of this report (operation manual) is to provide a simple and easy usage of MiST-BA for current and new users. MiST-BA consists of three parts; (1) Offline microscope control system for cell-finding. (2) Online microscope control system for cell-targeting and irradiating, and (3) Beam shutter control system for cell irradiation with a precise number of heavy ions. The report presents the outline of MiST-BA, the operation protocol of each part, examples of a microbeam irradiation experiment using CHO-K1 cells, silkworm eggs, and Tobacco protoplast cells, and Trouble shooting. (author)

  3. Characterization of BaBi2Ta2O9 prepared through amorphous precursor

    International Nuclear Information System (INIS)

    Maczka, M.; Kepinski, L.; Hermanowicz, K.; Dacko, S.; Czapla, Z.; Hanuza, J.

    2011-01-01

    Research highlights: → Formation of Bi-layered BaBi 2 Ta 2 O 9 proceeds via an intermediate fluorite phase. → Mechanochemical activation lowers the synthesis temperature by 150-200 deg. C. → The lateral size of the synthesized plate-like crystallites is about 100-200 nm. → Properties of the synthesized crystallites are different from the bulk material. - Abstract: Formation of ferroelectric BaBi 2 Ta 2 O 9 by annealing of an amorphous precursor prepared by high energy milling in ball mill has been studied by X-ray, scanning electron microscopy (SEM), Raman, infrared spectroscopy (IR), diffuse reflectivity and dielectric measurements. Our results show that formation of Bi-layered BaBi 2 Ta 2 O 9 proceeds via an intermediate fluorite phase. Mechanochemical activation allows obtaining BaBi 2 Ta 2 O 9 at short time and much lower temperatures than those required in a conventional solid state reaction. The lateral size of the plate-like crystallites is about 100-200 nm and properties of the synthesized particles are different compared to the bulk material.

  4. Polygyny without wealth: popularity in gift games predicts polygyny in BaYaka Pygmies.

    Science.gov (United States)

    Chaudhary, Nikhil; Salali, Gul Deniz; Thompson, James; Dyble, Mark; Page, Abigail; Smith, Daniel; Mace, Ruth; Migliano, Andrea Bamberg

    2015-05-01

    The occurrence of polygynous marriage in hunter-gatherer societies, which do not accumulate wealth, remains largely unexplored since resource availability is dependent on male hunting capacity and limited by the lack of storage. Hunter-gatherer societies offer the greatest insight in to human evolution since they represent the majority of our species' evolutionary history. In order to elucidate the evolution of hunter-gatherer polygyny, we study marriage patterns of BaYaka Pygmies. We investigate (i) rates of polygyny among BaYaka hunter-gatherers; (ii) whether polygyny confers a fitness benefit to BaYaka men; (iii) in the absence of wealth inequalities, what are the alternative explanations for polygyny among the BaYaka. To understand the latter, we explore differences in phenotypic quality (height and strength), and social capital (popularity in gift games). We find polygynous men have increased reproductive fitness; and that social capital and popularity but not phenotypic quality might have been important mechanisms by which some male hunter-gatherers sustained polygynous marriages before the onset of agriculture and wealth accumulation.

  5. Study on effect of cubic- and tetragonal phased BaTiO{sub 3} on the electrical and thermal properties of polymeric nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Thanki, A.A.; Goyal, R.K., E-mail: rkgoyal72@yahoo.co.in

    2016-11-01

    Polymer matrix nanocomposites based on polycarbonate (PC) and nanosized-cubic/tetragonal phases of barium titanate (BaTiO{sub 3}) were fabricated using a solution method followed by hot pressing. The content of both cubic- and tetragonal phased BaTiO{sub 3} was varied from 0 to 50 wt%. For a given weight fraction, the dielectric constant of the nanocomposites containing tetragonal BaTiO{sub 3} is more than those of cubic BaTiO{sub 3} filled nanocomposites. Moreover, cubic BaTiO{sub 3}/PC nanocomposites showed significantly lower dissipation factor than those of tetragonal BaTiO{sub 3}/PC nanocomposites. The dielectric constant of the nanocomposites was found to be frequency-independent. The microhardness of the nanocomposites increased with increase in the BaTiO{sub 3} content (both cubic- and tetragonal-phased) compared to the pure matrix. Scanning electron microscopy showed better dispersion and good interaction of the tetragonal BaTiO{sub 3} nanoparticles in the matrix. The addition of cubic BaTiO{sub 3} nanoparticles significantly reduced the thermal stability of the nanocomposites compared to matrix while the addition of tetragonal BaTiO{sub 3} nanoparticles decreased it slightly. The glass transition temperature of the cubic BaTiO{sub 3}/PC nanocomposites decreased significantly, whereas it reduced slightly for the tetragonal BaTiO{sub 3}/PC nanocomposites. - Highlights: • The effect of cubic-BaTiO{sub 3} and tetragonal-BaTiO{sub 3} nanoparticles were studied. • Cubic-BaTiO{sub 3} nanoparticles showed better microhardness. • Tetragonal-BaTiO{sub 3} nanoparticles showed better dielectric and thermal properties. • Frequency independent dielectric constants of the nanocomposites were observed.

  6. Effects of vacancies on atom displacement threshold energy calculations through Molecular Dynamics Methods in BaTiO3

    Science.gov (United States)

    Gonzalez Lazo, Eduardo; Cruz Inclán, Carlos M.; Rodríguez Rodríguez, Arturo; Guzmán Martínez, Fernando; Abreu Alfonso, Yamiel; Piñera Hernández, Ibrahin; Leyva Fabelo, Antonio

    2017-09-01

    A primary approach for evaluating the influence of point defects like vacancies on atom displacement threshold energies values Td in BaTiO3 is attempted. For this purpose Molecular Dynamics Methods, MD, were applied based on previous Td calculations on an ideal tetragonal crystalline structure. It is an important issue in achieving more realistic simulations of radiation damage effects in BaTiO3 ceramic materials. It also involves irradiated samples under severe radiation damage effects due to high fluency expositions. In addition to the above mentioned atom displacement events supported by a single primary knock-on atom, PKA, a new mechanism was introduced. It corresponds to the simultaneous excitation of two close primary knock-on atoms in BaTiO3, which might take place under a high flux irradiation. Therefore, two different BaTiO3 Td MD calculation trials were accomplished. Firstly, single PKA excitations in a defective BaTiO3 tetragonal crystalline structure, consisting in a 2×2×2 BaTiO3 perovskite like super cell, were considered. It contains vacancies on Ba and O atomic positions under the requirements of electrical charge balance. Alternatively, double PKA excitations in a perfect BaTiO3 tetragonal unit cell were also simulated. On this basis, the corresponding primary knock-on atom (PKA) defect formation probability functions were calculated at principal crystal directions, and compared with the previous one we calculated and reported at an ideal BaTiO3 tetrahedral crystal structure. As a general result, a diminution of Td values arises in present calculations in comparison with those calculated for single PKA excitation in an ideal BaTiO3 crystal structure.

  7. Mechanistic model for Sr and Ba release from severely damaged fuel

    International Nuclear Information System (INIS)

    Rest, J.; Cronenberg, A.W.

    1985-11-01

    Among radionuclides associated with fission product release during severe accidents, the primary ones with health consequences are the volatile species of I, Te, and Cs, and the next most important are Sr, Ba, and Ru. Considerable progress has been made in the mechanistic understanding of I, Cs, Te, and noble gas release; however, no capability presently exists for estimating the release of Sr, Ba, and Ru. This paper presents a description of the primary physical/chemical models recently incorporated into the FASTGRASS-VFP (volatile fission product) code for the estimation of Sr and Ba release. FASTGRASS-VFP release predictions are compared with two data sets: (1) data from out-of-reactor induction-heating experiments on declad low-burnup (1000 and 4000 MWd/t) pellets, and (2) data from the more recent in-reactor PBF Severe Fuel Damage Tests, in which one-meter-long, trace-irradiated (89 MWd/t) and normally irradiated (approx.35,000 MWd/t) fuel rods were tested under accident conditions. 10 refs

  8. Análise estatística de chuvas intensas na bacia hidrográfica do Rio Paraíba Statistical analysis of rains intense in the Paraíba River bas

    Directory of Open Access Journals (Sweden)

    Lincoln Eloi de Araújo

    2008-06-01

    Full Text Available Esta pesquisa foi realizada na bacia hidrográfica do rio Paraíba com a finalidade de identificar a variação espacial e temporal das chuvas intensas de 1, 2, 3, 4 e 5 dias. Os resultados obtidos mostraram concentração de valores máximos da variação espacial das chuvas intensas no leste da sub-bacia do Baixo Paraíba, Sul da sub-bacia do rio Taperoá e centro-norte da sub-bacia do Alto Paraíba. A análise da variação temporal revelou que os meses de maiores ocorrências de chuvas intensas na bacia em estudo são: janeiro, fevereiro, março e abril. Em seguida, as chuvas intensas foram ajustadas à função distribuição de probabilidade de Gumbel. O teste Kolmogorov-Smirnov foi utilizado para verificar a qualidade desses ajustes.This research was accomplished in the Paraíba river basin for to identify the space and temporal variability of the rains intense of 1, 2, 3, 4 and 5 days. The obtained results showed concentration of maximum values of the space variation of the rains intense in the east of the subbasin of Low Paraíba, south of the subbasin of the river Taperoá and center-north of the subbasin of High Paraíba. The analysis of the temporal variation did reveal that the months of larger occurrences of rains intense in the basin in study are: January, February, March and April. Soon after, the rains intense they were adjusted to the probability distribution function of Gumbel. The test Kolmogorov-Smirnov was used to verify the quality of those fittings.

  9. Long-term retention of 133Ba in the rat trachea following local administration as barium sulfate particles

    International Nuclear Information System (INIS)

    Takahashi, S.; Patrick, G.

    1987-01-01

    Long-term retention of 133 Ba in the trachea from intratracheally administered BaSO 4 particles was determined by both serial sacrifice and external scanning methods up to 6 months after injection. The amount of 133 Ba retained 1 week after injection in the caudal region of the trachea, where the tip of the cannula had been at injection, was 0.41% of the initial dose. Thereafter the 133 Ba was cleared exponentially with a mean half-time of 88 days, as determined from the autopsy samples. The cranial region of the trachea, including the site of the tracheostomy, contained 133 Ba at 10 times the level in the caudal region 1 week after injection and was cleared with a half-time of 66 days. These clearance rates were confirmed by repeated external scanning over the trachea. The 133Ba was drained to the lymph nodes not only in the thoracic cavity but also in the cervical region, suggesting the possibility of lymphatic drainage from the trachea to the cervical lymph nodes

  10. Synthesis and Dielectric Properties of Ba3NaBiNb10O30 Ceramics

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new niobate Ba3NaBiNb10O30 was synthesized by the solid state reaction.The reaction mixture was characterized by thermogravimetric and differential thermal analysis (TG-DTA),X-ray diffraction and dielectric constant measurements.The results show that Ba3NaBiNb10O30 has an orthorhombic tungsten bronze structure with space group Cmm2 and the unit cell parameters are a=1.7660(1) nm,a=1.7626(1) nm,c=0.78621(6) nm,Z=4.Ba3NaBiNb10O30 undergoes two phase transitions at 200℃ and 400℃,respectively.

  11. Enhanced Optical Performance of BaMgAl

    NARCIS (Netherlands)

    Yin, L.J.; Dong, Juntao; Wang, Yinping; Zhang, Bi; Zhou, Zheng Yang; Jian, Xian; Wu, Mengqiang; Xu, Xin; van Ommen, J.R.; Hintzen, H.T.J.M.

    2016-01-01

    Many strategies have been adopted to improve thermal degradation of phosphors. Because of the stability and high transmittance of graphene, here we report a novel method of carbon coating on BaMgAl10O17:Eu2+ (BAM) phosphor particles through chemical vapor

  12. Electron spin-resonance study on Ce{sup 3+} in BaLiF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yamaga, M. [Department of Electrical and Electronic Engineering, Faculty of Engineering, Gifu University, Gifu (Japan); Honda, M. [Faculty of Science, Naruto University of Education, Naruto (Japan); Shimamura, K.; Fukuda, T. [Institute for Materials Research, Tohoku University, Sendai (Japan); Yosida, T. [Nakanihon Automotive College, Kamo (Japan)

    2000-07-10

    Three distinct Ce{sup 3+} sites in BaLiF{sub 3} crystals estimated from the optical spectra are associated with configurations of Ce{sup 3+} accompanied by different charge compensators. This assignment is consistent with the electron spin-resonance (ESR) result that there are two tetragonal Ce{sup 3+} centres distorted along the [001] axis and two orthorhombic Ce{sup 3+} centres distorted along the [110] axis in the absence of the cubic centre. The configurations of the Ce{sup 3+} centres correspond to the substitution for Ba{sup 2+} ions along the [001] and [110] axes with Li{sup +} ions and the Ba{sup 2+}-ion vacancies along the [001] and [110] axes. The dominant component of the Ce{sup 3+} luminescence spectrum with the peak at {approx}320 nm and the large Stokes shift energy ({approx}8300 cm{sup -1}) is assigned as due to the substitution for a Ba{sup 2+} ion along the [001] axis with a Li{sup +} ion. As the ionic radius (0.74 A) of Li{sup +} is much smaller than that (1.60 A) of Ba{sup 2+}, the Li substitution produces more space, resulting in the large lattice relaxation in the 5d excited state of Ce{sup 3+}. (author)

  13. Impedance spectroscopy of Li2CO3 doped (Ba,Sr)TiO3 ceramic

    Science.gov (United States)

    Ham, Yong-Su; Koh, Jung-Hyuk

    2013-02-01

    (BaxSr1-x)TiO3-based ceramic has been considered as one of the most important electronic materials widely employed in microwave passive device applications. Many researches have been performed to lower the high sintering temperature, by adding various dopants such as B2O3, La2O3, etc. In our previous study, by adding Li2CO3 to (Ba0.5,Sr0.5)TiO3 ceramics, the sintering temperature of Li2CO3 doped (Ba0.5,Sr0.5)TiO3 ceramics decreased from 1350 to 900 °C. This study observed the crystalline structure and electrical properties of Li2CO3 doped (Ba0.5,Sr0.5)TiO3 ceramics. In scanning the crystalline structure of Li2CO3 doped (Ba0.5,Sr0.5)TiO3 ceramics, no pyro phase was observed by X-ray diffraction analysis. To investigate the electrical properties of Li2CO3 doped (Ba0.5,Sr0.5)TiO3 ceramics, real and imaginary parts of the impedances were analyzed. Complex impedance data were measured from 100 Hz to 1 MHz at various temperature ranges.

  14. Investigations on the local structures of Cu2+ at various BaO concentrations in 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO glasses

    Science.gov (United States)

    Jin, Jia-Rui; Wu, Shao-Yi; Hong, Jian; Liu, Shi-Nan; Song, Min-Xian; Teng, Bao-Hua; Wu, Ming-He

    2017-11-01

    The local structures and electron paramagnetic resonance (EPR) parameters for Cu2+ in 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO (BKZBC) glasses are theoretically investigated with distinct modifier BaO concentrations x (= 0, 6, 12, 18, 24 and 30 mol %). The ? clusters are found to undergo the relative tetragonal elongations of about 13.5 and 5.0% at zero and higher BaO concentrations. The concentration dependences of the measured d-d transition bands, g factors and A// are suitably reproduced from the Fourier type functions or sign functions of the relevant quantities with x by using only six adjustable parameters. The features of the EPR parameters and the local structures of Cu2+ are analysed in a consistent way by considering the differences in the local ligand field strength and electronic cloud admixtures around Cu2+ under addition of Ba2+ with the highest ionicity and polarisability. The present theoretical studies would be helpful to the researches on the structures, optical and EPR properties for the similar potassium barium zinc borate glasses containing copper with variation concentration of modifier BaO.

  15. Optimization in the preparation of the YBa2Cu3O7-δ compound using BaCO3 and BaO2 reagents

    International Nuclear Information System (INIS)

    Bustamante D, A.; Flores S, J.

    2004-01-01

    The traditional superconductor YBa 2 Cu 3 O 7-δ (Y123) has an orthorhombic crystalline structure with spatial group Pmmm and its critical temperature is 90K. The literature reports the use of reagent BaCO 3 for the preparation by the solid state reaction which requires one calcination and two thermal treatments in oxygen flow at 950 o C. In this work we report the comparison in the preparation of Y123 using the BaO 2 reagent as another possibility for preparation; in this case we have used only two thermal treatments in oxygen flow at 950 o C; therefore reducing the costs in preparation. The powder XRD pattern of samples prepared with BaO 2 confirm a well crystallized phase an the diffraction lines of the main phase can be indexed with an orthorhombic unit cell. The ac susceptibility measurement in the range 5-100 K using a Quantum Design (SQUID) magnetometer for two samples confirms the superconductor behavior with critical temperature Tc ≅ 91 K. The critical temperatures for these systems were found taken account the derivatives of the susceptibility curves. Scanning Electron Microscopy (SEM) confirms the good behavior of the grains corresponding to both methods. (orig.)

  16. Características microestructurales de varistores del sistema ZnO-BaO-P2O5

    Directory of Open Access Journals (Sweden)

    Fernández, J. F.

    1999-10-01

    Full Text Available Ceramic materials based on the system ZnO-BaO show a great potential for varistor applications. However, the BaO rich phase located at the grain boundaries shows high solubility in water which causes severe damage of the materials. In order to overcome this problem, doping with P2O5 to form BaZn2(PO42 and Zn3(PO42 has been studied. The resistance of these materials to degradation by moisture has been evaluated by lixiviation experiments. Sintering has been followed by means of dilatometric technique and microstructure was analysed by Scanning Electron Microscopy, SEM. The electrical properties of these materials evidence a varistor behaviour similar to that observed for materials in the system ZnO-BaO.Los materiales basados en el sistema ZnO-BaO presentan unas propiedades de gran interés para su aplicación como varistores. Sin embargo, la fase rica en BaO localizada en el borde de grano exhibe una solubilidad elevada en agua que origina una rápida degradación del material. Para soslayar este problema se ha estudiado la incorporación adicional de P2O5 con el objeto de formar las fases BaZn2(PO42 y Zn3(PO42. La estabilidad de estos nuevos materiales frente a la humedad se ha evaluado mediante ensayos de lixiviación. La sinterización se ha seguido mediante dilatometría y la microestructura de los materiales sinterizados se ha analizado por Microscopía Electrónica de Barrido, MEB. La respuesta eléctrica de los materiales muestra un comportamiento varistor comparable al que se observa en los del sistema binario ZnO-BaO.

  17. Using coral Ba/Ca records to investigate seasonal to decadal scale biogeochemical cycling in the surface and intermediate ocean.

    Science.gov (United States)

    LaVigne, M.; Cobb, K. M.; DeLong, K. L.; Freiberger, M. M.; Grottoli, A. G.; Hill, T. M.; Miller, H. R.; Nurhati, I. S.; Richey, J. N.; Serrato Marks, G.; Sherrell, R. M.

    2016-12-01

    Dissolved barium (BaSW), a bio-intermediate element, is linked to several biogeochemical processes such as the cycling and export of nutrients, organic carbon (Corg), and barite in surface and intermediate oceans. Dynamic BaSW cycling has been demonstrated in the water column on short timescales (days-weeks) while sedimentary records have documented geologic-scale changes in barite preservation driven by export production. Our understanding of how seasonal-decadal scale climate variability impacts these biogeochemical processes currently lacks robust records. Ba/Ca calibrations in surface and deep sea corals suggest barium is incorporated via cationic substitution in both aragonite and calcite. Here we demonstrate the utility of Ba/Ca for reconstructing biogeochemical variability using examples of surface and deep sea coral records. Century-long deep sea coral records from the California Current System (bamboo corals: 900-1500m) record interannual variations in Ba/Ca, likely reflecting changes in barite formation via bacterial Corg respiration or barite saturation state. A surface Porites coral Ba/Ca record from Christmas Island (central equatorial Pacific: 1978-1995) shows maxima during low productivity El Niño warm periods, suggesting that variations in BaSW are driven by biological removal via direct cellular uptake or indirectly via barite precipitation with the decomposition of large phytoplankton blooms at this location. Similarly, a sixteen-year long Siderastera siderea surface coral record from Dry Tortugas, FL (Gulf of Mexico: 1991-2007) shows seasonal Ba/Ca cycles that align with annual chlorophyll and δ13C. Taken together, these records demonstrate the linkages among Corg, nutrient cycling and BaSW in the surface and intermediate ocean on seasonal to decadal timescales. Multi-proxy paleoceanographic reconstructions including Ba/Ca have the potential to elucidate the mechanisms linking past climate, productivity, nutrients, and BaSW cycling in the past.

  18. Influence of adding BaSnO3 nanoparticles on magnetic transport properties for CuTl-1223 phase

    Directory of Open Access Journals (Sweden)

    M.ME. Barakat

    Full Text Available Co-precipitation method and solid-state reaction technique were used to synthesize BaSnO3 nanoparticles and (BaSnO3x/Cu0.5Tl0.5Ba2Ca2Cu3O10−δ samples, 0.00 ≤ x ≤ 1.50 wt%, respectively. All samples were characterized using X-ray powder diffraction (XRD and electrical resistivity measurements at different applied DC magnetic fields ranged from 0.29 to 4.40 kG. The relative volume fraction, superconducting transition temperature, Tc, and hole carriers concentration, P, were enhanced by increasing x up to 0.25 wt%, beyond which they were decreased for further increase in the addition of BaSnO3 nanoparticles. Both thermally activated flux creep (TAFC model and Ambegaokar and Halperin (AH theory were used to analyze the magnetoresistance data for (BaSnO3x/CuTl-1223 samples. An enhancement in the derived magnetic superconducting parameters, including the flux pinning energy, U, critical current density, Jc(0, and upper critical magnetic field, Bc2(0, as well as a decrement in the coherence length at 0 K, ξ(0, was achieved by adding BaSnO3 nanoparticles up to 0.25 wt%. A reverse trend was recorded for further addition of BaSnO3 nanoparticles. The electronic thermal conductivity, κe, was decreased by increasing applied magnetic fields below Tc. Keywords: CuTl-1223 phase, BaSnO3 nanoparticles, Flux pinning energy, Critical current density

  19. The effect of diameter ratio between transducers and reactor in sonication-assisted synthesis of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Manaf, A., E-mail: azwar@ui.ac.id; Fahmi, Agam Aidil [Department of Physics, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Yustanti, Erlina [Department of Physics, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Department of Metallurgy, Faculty of Engineering, University of Sultan AgengTirtayasa Jl. Jenderal Sudirman KM 03 Cilegon-Banten 65134 (Indonesia)

    2016-04-19

    This paper describes the particle size characterization of mechanically alloyed Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} prepared with the aid of a high-power ultrasonic destruction. Analytical-grade BaCO{sub 3}, TiO{sub 2} and SrCO{sub 3} with a purity greater than 99 wt.% were used as precursors for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3}. The mechanically powders were respectively sintered at 1200 °C for 3 hours to form crystalline powders. This work is aimed at studying the effect of diameter ratio between reactor and transducer of a high power sonicator on the Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} nanoparticles formation. The presence of a single phase of the two materials was confirmed by X-Ray Diffraction (XRD). The concentration of the particles in demineralized water was 3.0 g / 100 mL which become the object of 3 hours ultrasonic destruction subjected to the application of transducer in which the ratio between the diameter of the reactor and the transducer (D/d) was fixed at 1.4, 1.6 and 1.8 respectively. It was found that the mean particle size before the ultrasonic destruction was 538 nm for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and 480 nm for Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3}. With D/d of 1.8, the mean particle size of the two materials was found to decrease drastically to 38 nm and 24 nm, respectively. These mean particle sizes were respectively comparable with that of the crystallite size of the particles derived using the Whole Powder Pattern Modelling (WPPM) from which the mean crystallite size of 22 nm for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and 14 nm for Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} were obtained. It is then confirmed single nanocrystallite Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} particles were already achieved. We can conclude that the ultrasonic destruction to mechanically milled crystalline particles would be one

  20. Synthesis and electrical properties of BaBiO 3 and high resistivity BaTiO 3BaBiO 3 ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Nitish [Oregon State Univ., Corvallis, OR (United States); Univ. of New South Wales, Sydney, NSW (Australia); Golledge, Stephen L. [Univ. of Oregon, Eugene, OR (United States); Cann, David P. [Oregon State Univ., Corvallis, OR (United States)

    2016-12-01

    Ceramics of the composition BaBiO3 (BB) were sintered in oxygen to obtain a single phase with monoclinic II2/mm symmetry as suggested by high-resolution X-ray diffraction. X-ray photoelectron spectroscopy confirmed the presence of bismuth in two valence states - 3+ and 5+. Optical spectroscopy showed presence of a direct bandgap at ~ 2.2eV and a possible indirect bandgap at ~ 0.9eV. This combined with determination of the activation energy for conduction of 0.25eV, as obtained from ac impedance spectroscopy, suggested that a polaron-mediated conduction mechanism was prevalent in BB. The BB ceramics were crushed, mixed with BaTiO3 (BT), and sintered to obtain BT–BB solid solutions. All the ceramics had tetragonal symmetry and exhibited a normal ferroelectric-like dielectric response. Using ac impedance and optical spectroscopy, it was shown that resistivity values of BT–BB were orders of magnitude higher than BT or BB alone, indicating a change in the fundamental defect equilibrium conditions. A shift in the site occupancy of Bi to the A-site is proposed to be the mechanism for the increased electrical resistivity.

  1. Growing barium hexaferrite (BaFe{sub 12}O{sub 19}) thin films using chemical solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Budiawanti, Sri, E-mail: awanty77@yahoo.com [Graduate Program of Materials Science, Department of Physics, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Faculty of Teacher Training and Education, Sebelas Maret University (Indonesia); Soegijono, Bambang [Multiferroic Laboratory, Department of Physics, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia)

    2016-04-19

    Barium hexaferrite (BaFe{sub 12}O{sub 19}, or simply known as BaM) thin films has been recognized as a potential candidate for microwave-based devices, magnetic recording media and data storage. To grow BaM thin films, chemical solution deposition is conducted using the aqueous solution of metal nitrates, which involves spin coatings on Si substrates. Furthermore, Thermal Gravimeter Analysis (TGA), X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) are applied to evaluate the decomposition behavior, structure, morphology, and magnetic properties of BaM thin films. Additionally, the effects of number of layers variation are also investigated. Finally, magnetic properties analysis indicates the isotropic nature of the films.

  2. Growing barium hexaferrite (BaFe_1_2O_1_9) thin films using chemical solution deposition

    International Nuclear Information System (INIS)

    Budiawanti, Sri; Soegijono, Bambang

    2016-01-01

    Barium hexaferrite (BaFe_1_2O_1_9, or simply known as BaM) thin films has been recognized as a potential candidate for microwave-based devices, magnetic recording media and data storage. To grow BaM thin films, chemical solution deposition is conducted using the aqueous solution of metal nitrates, which involves spin coatings on Si substrates. Furthermore, Thermal Gravimeter Analysis (TGA), X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) are applied to evaluate the decomposition behavior, structure, morphology, and magnetic properties of BaM thin films. Additionally, the effects of number of layers variation are also investigated. Finally, magnetic properties analysis indicates the isotropic nature of the films.

  3. Fluorine dynamics in BaF2 superionic conductors investigated by NMR

    OpenAIRE

    Gumann, Patryk

    2008-01-01

    In this work the dynamics of fluorine in solid-state electrolytes having BaF2-structure was investigated using three different NMR-methods: field cycling relaxometry, lineshape analysis, and static field gradient NMR. For this purpose a pure BaF2 crystal, as well as crystals doped with trivalent impurities (LaF3), were studied as a function of temperature. The main goal of this investigation was to utilize the structure information provided by neutron scattering and MAS NMR data in order to s...

  4. New anisotropic rare earth fluorides BaR2F8(R=Y,Dy-Lu): growth and characterization

    International Nuclear Information System (INIS)

    Kaminskii, A.A.; Butashin, A.V.; Sulyanov, S.N.; Bagayev, S.N.; Eichler, H.J.; Findeisen, J.; Liu, B.; Taeuber, U.; Peuser, P.

    1998-01-01

    Polymorphism of BaR 2 F 8 compounds is analyzed, and some peculiarities of the crystal growth from the melt are discussed. We report on the orthorhombic BaLu 2 F 8 crystal with ordered structure, a new crystalline material for generating Ln 3+ activator ions. Spectroscopic and laser characteristics of Nd 3+ - and Er 3+ -doped BaLu 2 F 8 samples are discussed as representative examples. Besides, we pay special attention to monoclinic BaY 2 F 8 :Er 3+ crystals, as active media for highly efficient CW 3 μm laser-diode pumped lasers. (orig.)

  5. Hydrothermal synthesis and structural analysis of new mixed oxyanion borates: Ba11B26O44(PO4)2(OH)6, Li9BaB15O27(CO3) and Ba3Si2B6O16

    Science.gov (United States)

    Heyward, Carla; McMillen, Colin D.; Kolis, Joseph

    2013-07-01

    Several new borate compounds, Ba11B26O44(PO4)2(OH)6 (1), Li9BaB15O27(CO3) (2), and Ba3Si2B6O16 (3) were synthesized containing other hetero-oxyanion building blocks in addition to the borate frameworks. They were all prepared under hydrothermal conditions and characterized by single crystal and powder X-ray diffraction, and IR spectroscopy. Crystal data: For 1; space group P21/c, a=6.8909 (14) Å, b=13.629 (3) Å, c=25.851 (5) Å, β=90.04 (3)°; For 2; space group P-31c, a=8.8599 (13) Å, c=15.148 (3) Å; For 3; space group P-1, a=5.0414 (10) Å, b=7.5602 (15) Å, c=8.5374 (17) Å, α=77.15 (3)°, β=77.84 (3)°, γ=87.41 (3)° for 3. Compounds 1 and 2 contain isolated oxyanions [PO4]3- and [CO3]2- respectively, sitting in channels created by the borate framework, while structure 3 has the [SiO4]4- groups directly bonded to the borate groups creating a B-O-Si framework.

  6. Vortex pinning in artificially layered Ba(Fe,Co)2As2 film

    Science.gov (United States)

    Oh, M. J.; Lee, Jongmin; Seo, Sehun; Yoon, Sejun; Seo, M. S.; Park, S. Y.; Kim, Ho-Sup; Ha, Dong-Woo; Lee, Sanghan; Jo, Youn Jung

    2018-06-01

    Static high critical current densities (Jc) > 1 MA/cm2 with magnetic field parallel or perpendicular to c-axis were realized in Co-doped/undoped multilayerd BaFe2As2 films. We made a current bridge by FIB to allow precise measurements, and confirmed that the boundary quality using FIB was considerably better than the quality achieved using a laser. The presence of a high in-plane Jc suggested the existence of c-axis correlated vortex pinning centers. To clarify the relationship between the Jc performance and superstructures, we investigated the magnetic flux pinning mechanism using scaling theory of the volume pinning force Fp(H). The Jc(H) curves, Fp/Fp,max vs. h = H/Hirr curves, and parameters p and q depended on the characteristics of the flux pinning mechanism. It was found that the dominant pinning mechanism of Co-doped/undoped multilayerd BaFe2As2 films was Δl-pinning and the inserted undoped BaFe2As2 layers remained non-superconducting. The dominant pin geometry varied when the magnetic field direction changed. It was concluded that the artificially layered BaFe2As2 film is a 3-D superconductor due to its long correlation length compared to the thickness of the non-superconducting layer.

  7. Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials.

    Science.gov (United States)

    Jang, Seon-Min; Yang, Su Chul

    2018-06-08

    Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO 2 epitaxial growth and BaTiO 3 conversion. Through the TiO 2 epitaxial growth on FTO substrate, (001) oriented TiO 2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO 2 NBA was conducted to enlarge the surface area for effective Ba 2+ ion diffusion during the perovskite conversion process from TiO 2 to BaTiO 3 . The final structure of perovskite BaTiO 3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO 3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

  8. Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials

    Science.gov (United States)

    Jang, Seon-Min; Yang, Su Chul

    2018-06-01

    Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO2 epitaxial growth and BaTiO3 conversion. Through the TiO2 epitaxial growth on FTO substrate, (001) oriented TiO2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO2 NBA was conducted to enlarge the surface area for effective Ba2+ ion diffusion during the perovskite conversion process from TiO2 to BaTiO3. The final structure of perovskite BaTiO3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

  9. Band gap and mobility of epitaxial perovskite BaSn1 -xHfxO3 thin films

    Science.gov (United States)

    Shin, Juyeon; Lim, Jinyoung; Ha, Taewoo; Kim, Young Mo; Park, Chulkwon; Yu, Jaejun; Kim, Jae Hoon; Char, Kookrin

    2018-02-01

    A wide band-gap perovskite oxide BaSn O3 is attracting much attention due to its high electron mobility and oxygen stability. On the other hand, BaHf O3 was recently reported to be an effective high-k gate oxide. Here, we investigate the band gap and mobility of solid solutions of BaS n1 -xH fxO3 (x =0 -1 ) (BSHO) as a basis to build advanced perovskite oxide heterostructures. All the films were epitaxially grown on MgO substrates using pulsed laser deposition. Density functional theory calculations confirmed that Hf substitution does not create midgap states while increasing the band gap. From x-ray diffraction and optical transmittance measurements, the lattice constants and the band-gap values are significantly modified by Hf substitution. We also measured the transport properties of n -type La-doped BSHO films [(Ba ,La ) (Sn ,Hf ) O3 ] , investigating the feasibility of modulation doping in the BaSn O3/BSHO heterostructures. The Hall measurement data revealed that, as the Hf content increases, the activation rate of the La dopant decreases and the scattering rate of the electrons sharply increases. These properties of BSHO films may be useful for applications in various heterostructures based on the BaSn O3 system.

  10. The influence of mechanical activation on the morphological changes of Fe/BaTiO_3 powder

    International Nuclear Information System (INIS)

    Kosanović, D.; Obradović, N.; Pavlović, V.P.; Marković, S.; Maričić, A.; Rasić, G.; Vlahović, B.; Pavlović, V.B.; Ristić, M.M.

    2016-01-01

    Highlights: • Fe/BaTiO_3 ceramic was prepared using a solid-state reaction. • Powder mixture of 60% Fe and 40% BaTiO_3 was mechanically activated up to 240 min. • Microstructure was characterized using Powder XRD and SEM. • Thermal stability of the activated samples was investigated using DSC. • Raman spectrum changes with activation, along with atypical resonant scattering. - Abstract: Crystal structure and morphology of mechanically activated nanocrystalline Fe/BaTiO_3 was investigated using a combination of spectroscopic and microscopic methods. These show that mechanical activation led to the creation of new surfaces and the comminution of the initial powder particles. Prolonged milling resulted in formation of larger agglomerates of BaTiO_3 and bimodal particle size distribution, where BaTiO_3 particles were significantly larger than those of iron-containing phases. Milling times of 210 min and above lead to a significant decrease in temperature of the oxidation of iron in the sample, indicating abrupt change in reactivity. Raman spectroscopy analysis has revealed that activation had a pronounced influence on Fe/BaTiO_3 lattice, thereby affecting both the stability of the crystal structure and the phase transition phenomena.

  11. First-principles study of the (001) surface of cubic Ba0.5Sr0.5TiO3

    International Nuclear Information System (INIS)

    Wang, Yuan Xu

    2008-01-01

    We have theoretically investigated basic properties of the (001) surface of cubic Ba 0.5 Sr 0.5 TiO 3 (BST) by the plane-wave pseudopotential method within the local-density approximation. For the BaSrO 2 -terminated surface, the surface-layer Sr atoms move inward and the surface-layer Ba atoms move outward. Moreover, the displacement of the surface-layer Sr atoms is much larger than the surface-layer Ba atoms. The rumpling of the BaSrO 2 -terminated surface is much larger than that of the Ti 2 O 4 -terminated one. The surface state appears in the band structure of the Ti 2 O 4 -terminated surface of BST. Based on the results of the calculated grand thermodynamic potential, only the BaSrO 2 -terminated surface can exist in the (001) surface of cubic BST. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. La temperatura de transición en SrxBa1-xHfO3

    Directory of Open Access Journals (Sweden)

    López-García, A.

    2002-02-01

    Full Text Available In this contribution the transition temperature TC to the cubic phase in SrxBa1-xHfO3 compounds with x = 0.12, 0.25, 0.50, 0.75 and 0.88 is presented. These temperatures were deduced from the measurements of the perturbed angular correlation on tantalum probes. The purpose of this work is to study how the Sr substitution by Ba affect this temperature. The oxides BaHfO3 and SrHfO3 have at RT cubic and orthorhombic structures, respectively. The Sr-compound transform from tetragonal to cubic at TC1 ≈ 1400. From TC2 ≈ 1000K and up to TC1 the oxygen octahedra are tilted and the tilt angle decreases steadily as T approaches TC1. This rotation is originated by the interaction of strontium with oxygen because the Sr ionic radius (rSr ≈ 1.13 Å allows to be closer than Ba (rBa ≈ 1.35 Å. Then in SrxBa1-xHfO3 compounds a competition between the Ba-O interaction, 2.9502 Å apart and Sr-O interaction at a distance of 2.9098 Å in their respective pure compounds, is established.En este trabajo se presenta las temperaturas de transición TC a la estructura cúbica, en la familia de compuestos SrXBa1-XHfO3 donde x es igual a 0.12, 0.25, 0.50, 0.75 y 0.88, determinadas por medidas de la Correlación Angular Perturbada y usando al tantalio como sonda. El interés es estudiar como la sustitución de estroncio por bario modifica dicha temperatura. El BaHfO3 es cúbico a temperatura ambiente. En cambio, el SrHfO3 presenta una transición estructural de tetragonal a cúbica cuando TC1 ≈ 1400 K. Por debajo de esta temperatura y hasta TC2 ≈ 1000 K los octaedros de oxígeno están rotados uno con respecto al consecutivo, en un ángulo φ alrededor del eje z de la red tetragonal que disminuye a cero a medida que T→TC. Esta rotación está relacionada con la interacción del estroncio con el oxígeno, ya que el radio iónico del catión rSr (≈ 1.13 Å permite un mayor acercamiento entre ambos que el bario al oxígeno, pues rBa (≈ 1.35 Å. Entonces, en

  13. Dynamic Displacement Disorder of Cubic BaTiO3

    Science.gov (United States)

    Paściak, M.; Welberry, T. R.; Kulda, J.; Leoni, S.; Hlinka, J.

    2018-04-01

    The three-dimensional distribution of the x-ray diffuse scattering intensity of BaTiO3 has been recorded in a synchrotron experiment and simultaneously computed using molecular dynamics simulations of a shell model. Together, these have allowed the details of the disorder in paraelectric BaTiO3 to be clarified. The narrow sheets of diffuse scattering, related to the famous anisotropic longitudinal correlations of Ti ions, are shown to be caused by the overdamped anharmonic soft phonon branch. This finding demonstrates that the occurrence of narrow sheets of diffuse scattering agrees with a displacive picture of the cubic phase of this textbook ferroelectric material. The presented methodology allows one to go beyond the harmonic approximation in the analysis of phonons and phonon-related scattering.

  14. Quarkonium Spectroscopy And Search for New States at BaBar

    Energy Technology Data Exchange (ETDEWEB)

    Cibinetto, G.

    2011-11-04

    The BaBar experiment at the PEP-II B-factory gives excellent opportunities for the quarkonium spectroscopy. Investigation of the properties of new states like the X(3872), Y(3940) and Y(4260) are performed aiming to understand their nature. Recent BaBar results will be presented in this paper. At the B-factories charmonium and charmonium-like states are copiously produced via several mechanisms: in B decay (color suppressed b {yields} c transition), double charmonium production (e{sup +}e{sup -} {yields} c{bar c} + c{bar c}), two photons production ({gamma}*{gamma}* {yields} c{bar c}, where the c{bar c} state has positive C-parity) and in initial state radiation (ISR) when the e{sup {+-}} in its initial state emits a photon lowering the effective center of mass energy of the e{sup +}e{sup -} interaction (e{sup +}e{sup -} {yields} {gamma}{sub ISR} + c{bar c}, where the charmonium state has the quantum numbers J{sup PC} = 1{sup -2}). Many new states have been recently discovered at the B-factories, BaBar and Belle, above the D{bar D} threshold in the charmonium energy region. While some of them appear to be consistent with conventional c{sub c} states others do not fit with any expectation. Several interpretations for these states have been proposed: for some of them the mass values suggest that they could be conventional charmonia, but also other interpretations like D{sup 0}{bar D}*{sup 0} molecule or diquark-antidiquark states among many other models have been advanced. Reviews can be found in Refs. [1][2]. In all cases the picture is not completely clear. This situation could be remedied by a coherent search of the decay pattern to D{bar D}, search for production in two-photon fusion and ISR, and of course improving the statistical precision upon the current measurements. The BaBar experiment at the PEP-II asymmetric collider, designed to perform precision measurement of CP violation in the B meson system, has an extensive quarkonium spectroscopy program. Recent

  15. Electrochemical performance of BaSnO3 anode material for lithium-ion battery prepared by molten salt method

    CSIR Research Space (South Africa)

    Nithyadharseni, P

    2016-01-01

    Full Text Available Perovskite-like structure BaSnO(sub3) ceramic oxide has been prepared by low temperature molten salt method using KOH as a flux and Ba(OH)(sub2) and BaCl(sub2) as precursors. The as-prepared compounds were characterized by various techniques...

  16. Synthesis of transparent chloroborosilicate nanoglass-ceramics: Crystallization and growth mechanism of BaCl2 nanocrystals

    Directory of Open Access Journals (Sweden)

    Nilanjana Shasmal

    2015-12-01

    Full Text Available Oxyfluoride glass-ceramics are extensively being investigated for their excellent optical properties and widespread use in photonic applications. But oxychloride systems are scarcely studied although they are potential candidates for those fields. Here we report chloroborosilicate glass system SiO2–B2O3–BaO–K2O–Al2O3–BaCl2 (mol% within which BaCl2 nanocrystals have been generated by melt-quench technique followed by heat treatment. Samples were characterized by differential scanning calorimetry, X-ray diffraction, infrared and UV–vis spectroscopy, elastic constants measurement, etc. Micro- and nanostructures were analyzed by using FESEM, TEM and SAED. Formation and growth mechanism of BaCl2 nanocrystals have been demonstrated with the help of schematic representations. Size (7–47 nm and morphology of the nanocrystals were found to be controlled by temperature and heat-treatment time. Activation energy for crystallization was determined by non-isothermal method using DSC and found to be 510 kJ/mol. Chloroborosilicate glasses containing BaCl2 nanocrystals having low-phonon energy (∼350 cm−1 are promising for different photonic applications.

  17. Decay /sup 133/Ba

    Energy Technology Data Exchange (ETDEWEB)

    Singh, K; Hasiza, M L; Grewal, B S; Sahota, H S

    1982-07-01

    The relative gamma ray intensities of transitions in the decay of /sup 133/Ba have been measured using an intrinsic Ge detector. The electron capture branching ratios have been determined for 81, 161, 384 and 437 keV levels. The attenuation effect of long half-life of 81 keV levels has been studied in solid and liquid media. The electron capture decay has been investigated by changing the concentration of ethylene-diamine-tetraacetic acid (EDTA) environment. The 5/2/sup +/ yields 5/2/sup +/ 79.67 keV transition has an E0 to E2 intensity qsub(k)sup(2) <= 0.31. 10 refs., 4 figures.

  18. Anneden Allah'a: Bağlanma Teorisi ve İslâm'da Allah Tasavvuru

    OpenAIRE

    HAYTA, Akif

    2006-01-01

    John Bowlby tarafından geliştirilen bağlanma teorisi, yaşam boyu süren psikolojik bir sosyal ve kişilik gelişim teorisidir. Bağlanma teorisi bebek-çocuk ve bakıcısı arasındaki bağın gelişimi ve bu ilişkinin çeşitli fonksiyonlarının daha sonraki psikolojik gelişim üzerindeki etkilerine odaklanmıştır. Bağlanma teorisi bebek ve çocuk üzerine yapılan çalışmaları önemli derecede etkilemiş ve yığınla araştırmaya konu olmuştur. Aynı zamanda geniş bir alana yayılarak din psikolojisi araştırmalarında ...

  19. X-ray photoelectron spectroscopy study on Ba1-xEuxTiO3

    International Nuclear Information System (INIS)

    Lu, D.-Y.; Sugano, Mikio; Sun Xiuyun; Su Wenhui

    2005-01-01

    X-ray photoelectron spectroscopy is employed to study inner-shell core-level binding energies Eu 4d, Ti 2p and O 1s, Ba 3d for new single-phase Ba 1-x Eu x TiO 3 (0.1 ≤ x ≤ 0.4) samples prepared by solid state reaction at 4.0 GPa and 1090 deg. C. The peak positions of binding energies determined by linear background subtraction and Gaussian fit are presented. XPS analysis indicates that the mixed-valent Eu 3+ /Eu 2+ ions at A-site and Ti 4+ /Ti 3+ ions at B-site coexisted in the Ba 1-x Eu x TiO 3 powder surface, and the amount of Eu 2+ ions is equal to Eu 3+ ions

  20. Hexagonal perovskites with cationic vacancies. 25. Hexagonal 5 L stacking polytypes in the systems Ba/sub 5/BaWsub(3-x)sup(VI)Msub(x)sup(V)vacantOsub(15-x/2)vacantsub(x/2) with Msup(V) = Nb, Ta

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-12-01

    In the systems BaO-M/sub 2/sup(V)O/sub 5/-WO/sub 3/ (Msup(V) = Nb, Ta) a new phase Ba/sub 5/BaWsub(3-x)Msub(x)sup(V)vacantOsub(15-x/2)vacantsub(x/2) with hexagonal 5 L structure (sequence hhccc; space group P-3m1) could be prepared. The range of existence is restricted to Msup(V) containing compounds. With Msup(V) = Nb the lower phase boundary is x = 3. In the Ta system it is reached between x = 2 and 3; the pure Ta pervoskite (Ba:Ta:O = 6:3:13 1/2 = 4:2:9) represents the final member of the series Ba/sub 3/Srsub(1-y)Basub(y)Ta/sub 2/O/sub 9/ with y = 1.

  1. Comparison of rheological, mechanical, electrical properties of HDPE filled with BaTiO{sub 3} with different polar surface tension

    Energy Technology Data Exchange (ETDEWEB)

    Su, Jun [Department of Polymer Science and Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China); College of Mechanics Engineering, Nanjing Institute of Industry Technology, Nanjing, 210023 (China); Zhang, Jun, E-mail: zhangjun@njtech.edu.cn [Department of Polymer Science and Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China)

    2016-12-01

    Graphical abstract: - Highlights: • The non-polar and short vinyl groups can greatly reduce G′ of HDPE composites. • Long chains on BaTiO{sub 3} surface enhance the interaction of BaTiO{sub 3} with HDPE. • Polar amino groups on BaTiO{sub 3} surface raise the interaction of BaTiO{sub 3} with HDPE. • Polar amino groups can boost the dielectric constant of HDPE composites. • The potential use in electronic equipment of the KH550 composites is obtained. - Abstract: In this work, three types of coupling agents: isopropyl trioleic titanate (NDZ105), vinyltriethoxysilane (SG-Si151), 3-aminopropyltriethoxysilane (KH550) were applied to modify the surface tension of Barium titanate (BaTiO{sub 3}) particles. The Fourier transform infrared (FT-IR) spectra confirm the chemical adherence of coupling agents to the particle surface. The long hydrocarbon chains in NDZ105 can cover the particle surface and reduce the polar surface tension of BaTiO{sub 3} from 37.53 mJ/m{sup 2} to 7.51 mJ/m{sup 2}, turning it from hydrophilic to oleophilic properties. The short and non-polar vinyl groups in SG-Si151 does not influence the surface tension of BaTiO{sub 3}, but make BaTiO{sub 3} have both hydrophilic and oleophilic properties. The polar amino in KH550 can keep BaTiO{sub 3} still with hydrophilic properties. It is found that SG-Si151 modified BaTiO{sub 3} has the lowest interaction with HDPE matrix, lowering the storage modulus of HDPE composites to the greatest extent. As for mechanical properties, the polar amino groups in KH550 on BaTiO{sub 3} surface can improve the adhesion of BaTiO{sub 3} with HDPE matrix, which increases the elongation at break of HDPE composites to the greatest extent. In terms of electrical properties, the polar amino groups on surface of BaTiO{sub 3} can boost the dielectric properties of HDPE/BaTiO{sub 3} composites and decrease the volume resistivity of HDPE/BaTiO{sub 3} composites. The aim of this study is to investigate how functional groups

  2. Steam Electrolysis by Proton-Conducting Solid Oxide Electrolysis Cells (SOECs) with Chemically Stable BaZrO3-Based Electrolytes

    KAUST Repository

    Bi, Lei

    2015-07-17

    BaZrO3-based material was applied as the electrolyte for proton-conducting solid oxide fuel cells (SOECs). Compared with the instability of BaCeO3-based proton-conductors, BaZrO3-based material could be a more promising candidate for proton-conducting SOECs due to its excellent chemical stability under H2O conditions, but few reports on this aspect has been made due to the processing difficulty for BaZrO3. Our recent pioneering work has demonstrated the feasibility of using BaZrO3-based electrolyte for SOECs and the fabricated cell achieves relatively high cell performance, which is comparable or even higher than that for BaCeO3-based SOECs and offers better chemical stability. Cell performance can be further improved by tailoring the electrolyte and electrode. © The Electrochemical Society.

  3. Highly constrained ferroelectric [BaTiO3](1−x)Λ/[BaZrO3]xΛ superlattices: X-ray diffraction and Raman spectroscopy

    International Nuclear Information System (INIS)

    Belhadi, J.; El Marssi, M.; Gagou, Y.; El Mendili, Y.; Bouyanfif, H.; Yuzyuk, Yu. I.; Raevski, I. P.; Wolfman, J.

    2014-01-01

    We report an x-ray diffraction (XRD) and a Raman-scattering investigation of ferroelectric/paraelectric superlattices [BaTiO 3 ] (1−x)Λ /[BaZrO 3 ] xΛ for which the composition varied, 0.15 ≤ x ≤ 0.85, while the superlattice (SL) modulation period Λ was kept constant at about 100 Å. The samples were epitaxially grown by pulsed laser deposition on MgO substrates buffered with La 0.5 Sr 0.5 CoO 3 . Based on the XRD analysis and on polarized Raman spectra, we have showed that the large strain in SLs induced ferroelectricity in BaZrO 3 (BZ) for all SLs, a material that is paraelectric in the bulk form at any temperature and in the single film. The induced polar axis in BZ layers is perpendicular to the plane of substrate while BaTiO 3 (BT) layers exhibit in-plane polar orientation. Raman spectroscopy revealed a lattice ordering in SLs due to the misfit strain generated by the large lattice mismatch between the alternating BZ and BT layers. This strain induced a huge upward frequency of the lowest E(1TO) soft mode from 60 cm −1 in the BT single film to 215 cm −1 in the SL with x = 0.85. These results show that in spite of relatively large periodicity of SLs, they are highly constrained and the variation of BZ ratio allowed modifying strains between layers. The temperature dependence of the Raman spectra for BT 0.3Λ /BZ 0.7Λ and BT 0.7Λ /BZ 0.3Λ samples revealed giant shift of the ferroelectric phase transition. The phase transition temperature was found to be upshifted by about 300 °C with respect to BT single crystal.

  4. Cetuximab tedavisine bağlı trikomegali: 4 olgu sunumu

    OpenAIRE

    Ordu, Çetin; Pilancı, Kezban Nur; Okutur, Kerem; Sağlam, Sezer; Demir, Osman Gökhan; Köksal, Ülkühan İner

    2014-01-01

    Amaç: Cetuximab, kolorektal kanserler ve baş-boyun kanserlerinin tedavisinde kullanılan, epidermal büyüme faktörü reseptörüne (EGFR) karşı geliştirilmiş bir monoklonal antikordur. En önemli yan etkisi cilt toksisitesidir. Cetuximab ile ilişkili kıllanma değişiklikleri ise trikomegali (kaş ve kirpiklerde anormal uzama, kıvrılma, kalınlaşma) ve hipertrikozisdir. Çalışmamızda 4 kolorektal kanser olgusunda cetuximaba bağlı trikomegali yan etkisi sunulmuştur. Hastaların genel özellikleri Tablo 1' ...

  5. Dynamic moments of inertia in Xe, Cs and Ba nuclei

    International Nuclear Information System (INIS)

    El-Samman, H.; Barci, V.; Gizon, A.

    1984-01-01

    The γ-rays following the reactions induced by 12 C ions on 115 In, 112 , 117 , 122 Sn and 123 Sb targets have been investigated using six NaI(Tl) detectors in a two-dimensional arrangement. The collective moment of inertia I( 2 ) /sub band/ of 118 , 122 Xe, 123 Cs and 128 , 130 Ba have been extracted from the energy-correlation spectra. The behaviour of these nuclei and the observed differences are interpreted in terms of high-spin collective properties. Data are also presented on the effective moment of inertia I( 2 )/sub eff/ of 118 Xe and 130 Ba measured by sum-spectrometer techniques. 13 references

  6. Electronic structure of PrBa2Cu3O7

    International Nuclear Information System (INIS)

    Singh, D.J.

    1994-01-01

    Electronic-structure calculations, within the local spin density approximation (LSDA), are reported for PrBa 2 Cu 3 O 7 . Significant charge transfer from the Pr ions to both the CuO 2 planes and the chains is found relative to YBa 2 Cu 3 O 7 . This supports hole depletion explanations for the insulating character of PrBa 2 Cu 3 O 7 . The LSDA electronic structure shows a prominent ''ridge'' Fermi surface analogous to that in YBa 2 Cu 3 O 7 , but broader. It is proposed that high-resolution positron measurements of this width may provide a useful test of hole depletion models

  7. Phonon modes in Gd1-xCexBa2Cu3O7-δ

    Directory of Open Access Journals (Sweden)

    SH Mozaffari

    2009-08-01

    Full Text Available  XRD and Raman analyses were performed to probe the phase formation and the variation of the normal phonon frequencies of the high temperature superconductor GdBa2Cu3O7-δ upon Ce doping. It was found that in addition to the orthorhombic 123 phase, some nonsuperconducting peaks, which are mainly due to the BaCeO3 secondary phase, are also formed that suppress the superconducting transition temperature. Besides, analysis of the Raman peaks shows that substitutions of Ce for Gd in GdBa2Cu3O7-δ are restricted to low concentrations in favor of impurity island formation .

  8. Thermophysical properties of proton conducting perovskite: BaCeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Aarti, E-mail: aarti.phy@gmail.com; Parey, Vanshree; Thakur, Rasna; Shrivastava, Archana; Gaur, N. K. [Department of Physics, Barkatullah University, Bhopal-462026 (India)

    2015-06-24

    We present the thermal properties of the proton conducting orthorhombic BaCeO{sub 3} by the means of a Rigid Ion Model (RIM). We report the cohesive energy (φ), Reststrahlen frequency (υ), Debye temperature (θ{sub D}) and Gruneisen parameter (γ). The value of Gruneisen parameter (γ), which supports the earlier, reported values. Besides, the specific heat values presented in this work by using RIM are in reasonable agreement with the available experimental data for BaCeO{sub 3} at low temperature (2K ≤ T ≤ 300K)

  9. Magnetic moment measurement of 140Ba nuclei using transient field technique

    International Nuclear Information System (INIS)

    Saxena, Mansi; Mandal, S.; Siwal, Davinder; Rainovski, G.; Danchev, M.; Damyanova, A.; Gladnishki, K.; Leske, J.; Bauer, C.; Bloch, T.; John, P.; Pietralla, N.; Wollersheim, H.J.; Kojouharov, I.; Pietri, S.; Schaffner, H.

    2011-01-01

    Mixed symmetry states have been identified in the neutron proton version of the Interacting Boson Model. The motivation of this experiment is to identify uniquely one phonon mixed symmetry states in 140 Ba nuclei by g factor measurement of the states. Magnetic moments measurements provide substantial information on the microscopic structure of the nuclei as the magnetic moment of a nuclei is described by the wave function of one state only. In this present paper we report the preliminary results of the g factor measurement of the first 2 + state of 140 Ba

  10. Syntheses of nanocrystalline BaTiO3 and their optical properties

    Science.gov (United States)

    Yu, J.; Chu, J.; Zhang, M.

    Stoichiometric and titanium-excess nanocrystalline barium titanates were synthesized using a hydrothermal process at various hydrothermal temperatures and with further heat treatment at 500 °C and 900 °C. Owing to the different process conditions, the excess titanium exists in different states and configurations within the nanocrystalline BaTiO3 matrix; this was demonstrated by X-ray diffraction, Raman scattering, and photoluminescence. In these nanocrystalline BaTiO3, the 590, 571, 543 and 694 nm light emission bands were observed; mechanisms leading to such emissions were also discussed.

  11. Kulturna baština - poticatelj dječjeg razvoja (likovni aspekt)

    OpenAIRE

    Kuščević, Dubravka

    2015-01-01

    Kulturna baština slika je života određene društvene zajednice, a nastala je kao posljedica mnogih povijesnih previranja te je kao takva predmet proučavanja mnogih znanstvenih disciplina. Bez kulturne uvjetovanosti nije moguće shvatiti povijest i razvoj naroda i društava, a bez kulture, s obzirom da predstavlja temeljnu antropološku komunikaciju, nije moguć ni život pojedinca u zajednici. Mnogi oblici kulturne baštine kriju u sebi različita povijesna značenja koja produbljuju spoznaju stvar...

  12. Improved osteoblasts growth on osteomimetic hydroxyapatite/BaTiO{sub 3} composites with aligned lamellar porous structure

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Beilei [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); Chen, Liangjian, E-mail: jian007040@sina.com [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Shao, Chunsheng [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); Zhang, Fuqiang; Zhou, Kechao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Cao, Jun [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); Zhang, Dou, E-mail: dzhang@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

    2016-04-01

    Osteoblasts growing into bone substitute is an important step of bone regeneration. This study prepared porous hydroxyapatite (HA)/BaTiO{sub 3} piezoelectric composites with porosity of 40%, 50% and 60% by ice-templating method. Effects of HA/BaTiO{sub 3} composites with different porosities, with and without polarizing treatment on adhesion, proliferation and differentiation of osteoblasts were investigated in vitro. Results revealed that cell densities of the porous groups were significantly higher than those of the dense group (p < 0.05), so did the alkaline phosphate (ALP) and bone gla protein (BGP) activities. Porosity of 50% group exhibited higher ALP activity and BGP activity than those of the 40% and 60% groups. Scanning electron microscopy (SEM) observations revealed that osteoblasts adhered and stretched better on porous HA/BaTiO{sub 3} than on the dense one, especially HA/BaTiO{sub 3} with porosity of 50% and 60%. However, there was no significant difference in the cell morphology, cell densities, ALP and BGP activities between the polarized group and the non-polarized group (p > 0.05). The absence of mechanical loading on the polarized samples may account for this. The results indicated that hierarchically porous HA/BaTiO{sub 3} played a favorable part in osteoblasts proliferation, differentiation and adhesion process and is a promising bone substitute material. - Graphical abstract: Aligned porous structure of HA/BaTiO{sub 3} piezoelectric composites prepared by ice-templating method was similar to the lamellar Haversian system in bone tissue. When co-cultured with human osteosarcoma cells (MG63), porous HA/BaTiO{sub 3} composites exhibited remarkable biological activity in promoting proliferation, differentiation and adhesion of MG63 cells. - Highlights: • The aligned porous structure of HA/BaTiO{sub 3} composite was similar to the lamellar Haversian system in bone tissue. • The piezoelectric d{sub 33} coefficient of HA/BaTiO{sub 3} with porosity

  13. Preparation, photoluminescent properties and luminescent dynamics of BaAlF{sub 5}:Eu{sup 2+} nanophosphors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei [Stem Cell and Tissue Engineering Laboratory, Dalian University of Technology, Dalian, Liaoning 116023 (China); College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China); Hua, Ruinian, E-mail: rnhua@dlnu.edu.cn [College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China); Liu, Tianqing, E-mail: liutq@dlut.edu.cn [Stem Cell and Tissue Engineering Laboratory, Dalian University of Technology, Dalian, Liaoning 116023 (China); Zhao, Jun [College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China); Department of Physics, Dalian Maritime University, Dalian, Liaoning 116026 (China); Na, Liyan [College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China); Chen, Baojiu [Department of Physics, Dalian Maritime University, Dalian, Liaoning 116026 (China)

    2014-12-15

    Graphical abstract: Rice-shaped BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via one-pot hydrothermal process. The as-prepared BaAlF{sub 5}:Eu{sup 2+} are composed of many particles with an average diameter of 40 nm. When excited at 260 nm, the sharp line emission located at 361 nm of Eu{sup 2+} was observed. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The strong ultraviolet emission of Eu{sup 2+} ions in BaAlF{sub 5}:Eu{sup 2+} nanoparticles suggests that these nanoparticles may have potential applications for sensing, solid-state lasers and spectrometer calibration. - Highlights: • BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via a mild hydrothermal process. • The Van and Huang models were used to research the mechanism of concentration quenching. • The optimum doping concentration of Eu2+ was confirmed to be 5 mol%. - Abstract: Eu{sup 2+}-doped BaAlF{sub 5} nanophosphors were synthesized via a facile one-pot hydrothermal method. The final products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. XRD results showed that the prepared samples are single-phase. The FE-SEM and TEM images indicated that the prepared BaAlF{sub 5}:Eu{sup 2+} nanophosphors are composed of many rice-shaped particles with an average diameter of 40 nm. When excited at 260 nm, BaAlF{sub 5}:Eu{sup 2+} nanophosphors exhibit the sharp line emissions of Eu{sup 2+} at room temperature. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The Van and Huang models were used to study the mechanism of concentration quenching and the electric dipole–dipole interaction between Eu{sup 2+} can be deduced to be a dominant for quenching fluorescence in BaAlF{sub 5}:Eu{sup 2+} nanophosphors. The strong ultraviolet emission of Eu{sup 2+} in BaAlF{sub 5}:Eu{sup 2+} nanophosphors suggests that

  14. BaFe{sub 12}O{sub 19} powder with high magnetization prepared by acetone-aided coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hsuan-Fu, E-mail: hfyu@mail.tku.edu.tw

    2013-09-15

    BaFe{sub 12}O{sub 19} particles with high magnetization were produced using an acetone-aided coprecipitation process. An aqueous solution of iron and barium nitrates, in an Fe{sup 3+}/Ba{sup 2+} molar ratio of 12, was added in a stirred precipitation liquid medium composed of H{sub 2}O, CH{sub 3}(CO)CH{sub 3} and NH{sub 4}OH. After reacting metallic ions with ammonia, the precipitates were formed, centrifugally filtered, freeze dried and calcined. Effects of amount of the acetone in the precipitation liquid medium on the formation of crystalline BaFe{sub 12}O{sub 19} were investigated. The presence of acetone in the precipitation liquid medium can greatly promote formation of the crystalline BaFe{sub 12}O{sub 19} at temperature as low as 650 °C and can enhance magnetization of the derived particles. On the other hand, raising the calcination temperature can effectively accelerate development of crystallite morphology and magnetic characters of the barium hexaferrites. While the barium hexaferrite powder obtained without acetone additions and calcined at 1000 °C had magnetization (measured at 50 kOe; M(50 kOe)) of 63.5 emu/g, remanence magnetization (Mr) of 31.3 emu/g and coercivity (Hc) of 4.7 kOe, the single magnetic domain size BaFe{sub 12}O{sub 19} powder with M(50 kOe) of 70.6 emu/g, Mr of 34.4 emu/g and Hc of 3.7 kOe was produced at 1000 °C, using a precipitation liquid medium of 64 vol% acetone. - Highlights: • BaFe{sub 12}O{sub 19} with high magnetic characters was produced by an acetone-aided coprecipitation. • The effects of acetone addition in the precipitation on the formation of BaFe{sub 12}O{sub 19} were studied. • Acetone presence in the precipitation liquid medium promoted BaFe{sub 12}O{sub 19} formation at ≥650 °C. • BaFe{sub 12}O{sub 19} with M(50 kOe) of 70.6 emu/g, Mr of 34.4 emu/g and Hc of 3.7 kOe was obtained.

  15. AMiBA: BROADBAND HETERODYNE COSMIC MICROWAVE BACKGROUND INTERFEROMETRY

    International Nuclear Information System (INIS)

    Chen, M.-T.; Li, C.-T.; Hwang, Y.-J.; Jiang Homin; Altamirano, Pablo; Chang, C.-H.; Chang, S.-H.; Chang, S.-W.; Han, C.-C.; Huang, Y.-D.; Kubo, Derek; Martin-Cocher, Pierre; Oshiro, Peter; Raffin, Philippe; Wei Tashun; Chiueh, T.-D.; Chu, T.-H.; Wang Huei; Kesteven, Michael; Wilson, Warwick

    2009-01-01

    The Y. T. Lee Array for Microwave Background (AMiBA) has reported the first results on the detection of galaxy clusters via the Sunyaev-Zel'dovich effect. The objectives required small reflectors in order to sample large-scale structures (20'), while interferometry provided modest resolutions (2'). With these constraints, we designed for the best sensitivity by utilizing the maximum possible continuum bandwidth matched to the atmospheric window at 86-102 GHz, with dual polarizations. A novel wide-band analog correlator was designed that is easily expandable for more interferometer elements. Monolithic millimeter-wave integrated circuit technology was used throughout as much as possible in order to miniaturize the components and to enhance mass production. These designs will find application in other upcoming astronomy projects. AMiBA is now in operation since 2006, and we are in the process to expand the array from seven to 13 elements.

  16. Layered SmBaCuCoO5+δ and SmBaCuFeO5+δ perovskite oxides as cathode materials for proton-conducting SOFCs

    International Nuclear Information System (INIS)

    Nian Qiong; Zhao Ling; He Beibei; Lin Bin; Peng Ranran; Meng Guangyao; Liu Xingqin

    2010-01-01

    A dense BaCe 0.8 Sm 0.2 O 5+δ (BCS) electrolyte was fabricated on a porous anode by in situ drop-coating to develop a simple and cost-effective route to fabricate proton-conducting solid oxide fuel cells (SOFCs). Layered perovskite-structure oxides SmBaCuCoO 5+δ (SBCC) and SmBaCuFeO 5+δ (SBCF) were prepared and the electrical conductivity, the thermal expansion coefficient and electrochemical performance were investigated as potential cathode materials for proton-conducting SOFCs. Thermal expansion coefficients of SBCC and SBCF were suitable for BCS electrolyte and the electrical conductivity of the SBCC is higher than that of the SBCF. The maximum power density of 449 mW cm 2 and 333 mW cm 2 at 700 o C were obtained for the SBCC/BCS/NiO-BCS and SBCF/BCS/NiO-BCS cells, respectively. The interfacial polarization resistances for SBCC and SBCF cathode are as low as 0.137 Ω cm -2 and 0.196 Ω cm -2 at 700 o C, respectively. The results indicate that the SBCC and SBCF are promising cathode materials for proton-conducting SOFCs.

  17. Precipitation method for barium metaborate (BaB2O4) synthesis from borax solution

    International Nuclear Information System (INIS)

    Akşener, Eymen; Figen, Aysel Kantürk; Pişkin, Sabriye

    2013-01-01

    In this study, barium metaborate (BaB 2 O 4 , BMB) synthesis from the borax solution was carried out. BMB currently is used in production of ceramic glazes, luminophors, oxide cathodes as well as additives to pigments for aqueous emulsion paints and also β−BaB 2 O 4 single crystals are the best candidate for fabrication of solid-state UV lasers operating at a wavelength of 200 nm due to excellent nonlinear optical properties. In the present study, synthesis was carried out from the borax solution (Na 2 B 4 O 7⋅ 10H 2 O, BDH) and barium chloride (BaCI 2⋅ 2H 2 O, Ba) in the glass-batch reactor with stirring. The effect of, times (5-15 min), molar ratio [stoich.ration (1.0:2.0), 1.25:2.0, 1.5:2.0, 2.5:2:0, 3.0:2.0, 3.5:2.0,4.0:2.0, 5.0:2.0] and also crystallization time (2-6 hour) on the BMB yield (%) was investigated at 80 °C reaction temperature. It is found that, BMB precipitation synthesis with 90 % yield can be performed from 0.50 molar ration (BDH:Ba), under 80 °C, 15 minute, and 6 hours crystallization time. The structural properties of BMB powders were characterized by using XRD, FT-IR and DTA-TG instrumental analysis technique

  18. Precipitation method for barium metaborate (BaB2O4) synthesis from borax solution

    Science.gov (United States)

    Akşener, Eymen; Figen, Aysel Kantürk; Pişkin, Sabriye

    2013-12-01

    In this study, barium metaborate (BaB2O4, BMB) synthesis from the borax solution was carried out. BMB currently is used in production of ceramic glazes, luminophors, oxide cathodes as well as additives to pigments for aqueous emulsion paints and also β-BaB2O4 single crystals are the best candidate for fabrication of solid-state UV lasers operating at a wavelength of 200 nm due to excellent nonlinear optical properties. In the present study, synthesis was carried out from the borax solution (Na2B4O7ṡ10H2O, BDH) and barium chloride (BaCI2ṡ2H2O, Ba) in the glass-batch reactor with stirring. The effect of, times (5-15 min), molar ratio [stoich.ration (1.0:2.0), 1.25:2.0, 1.5:2.0, 2.5:2:0, 3.0:2.0, 3.5:2.0,4.0:2.0, 5.0:2.0] and also crystallization time (2-6 hour) on the BMB yield (%) was investigated at 80 °C reaction temperature. It is found that, BMB precipitation synthesis with 90 % yield can be performed from 0.50 molar ration (BDH:Ba), under 80 °C, 15 minute, and 6 hours crystallization time. The structural properties of BMB powders were characterized by using XRD, FT-IR and DTA-TG instrumental analysis technique.

  19. Ultrasonic investigations on polonides of Ba, Ca, and Pb

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Devraj; Bhalla, Vyoma [Amity School of Engineering and Technology, New Delhi (India). Dept. of Applied Physics; Bala, Jyoti [Amity School of Engineering and Technology, New Delhi (India). Dept. of Applied Physics; Guru Gobind Singh Indraprastha Univ., New Delhi (India). USICT; Wadhwa, Shikha [Amity Univ., Noida (India). Amity Inst. of Nanotechnology

    2017-07-01

    The temperature-dependent mechanical and ultrasonic properties of barium, calcium, and lead polonides (BaPo, CaPo, and PbPo) were investigated in the temperature range 100-300 K. The second- and third-order elastic constants (SOECs and TOECs) were computed using Coulomb and Born-Mayer potential and these in turn have been used to estimate other secondary elastic properties such as strength, anisotropy, microhardness, etc. The theoretical approach followed the prediction that BaPo, CaPo, and PbPo are brittle in nature. PbPo is found to be the hardest amongst the chosen compounds. Further the SOECs and TOECs are applied to determine ultrasonic velocities, Debye temperature, and acoustic coupling constants along left angle 100 right angle, left angle 110 right angle, and left angle 111 right angle orientations at room temperature. Additionally thermal conductivity has been computed using Morelli and Slack's approach along different crystallographic directions at room temperature. Finally ultrasonic attenuation due to phonon-phonon interaction and thermoelastic relaxation mechanisms has been computed for BaPo, CaPo, and PbPo. The behaviour of these compounds is similar to that of semi-metals with thermal relaxation time of the order 10{sup -11} s. The present computation study is reasonably in agreement with the available theoretical data for the similar type of materials.

  20. Pre-Training Reversible Inactivation of the Basal Amygdala (BA Disrupts Contextual, but Not Auditory, Fear Conditioning, in Rats.

    Directory of Open Access Journals (Sweden)

    Elisa Mari Akagi Jordão

    Full Text Available The basolateral amygdala complex (BLA, including the lateral (LA, basal (BA and accessory basal (AB nuclei, is involved in acquisition of contextual and auditory fear conditioning. The BA is one of the main targets for hippocampal information, a brain structure critical for contextual learning, which integrates several discrete stimuli into a single configural representation. Congruent with the hodology, selective neurotoxic damage to the BA results in impairments in contextual, but not auditory, fear conditioning, similarly to the behavioral impairments found after hippocampal damage. This study evaluated the effects of muscimol-induced reversible inactivation of the BA during a simultaneous contextual and auditory fear conditioning training on later fear responses to both the context and the tone, tested separately, without muscimol administration. As compared to control rats micro-infused with vehicle, subjects micro-infused with muscimol before training exhibited, during testing without muscimol, significant reduction of freezing responses to the conditioned context, but not to the conditioned tone. Therefore, reversible inactivation of the BA during training impaired contextual, but not auditory fear conditioning, thus confirming and extending similar behavioral observations following selective neurotoxic damage to the BA and, in addition, revealing that this effect is not related to the lack of a functional BA during testing.