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Sample records for gavi ba estefade

  1. GAVI and hepatitis B immunisation in India.

    PubMed

    Kolås, A

    2011-01-01

    In cooperation with Indian health authorities, the GAVI Alliance (GAVI) is introducing Hepatitis B (HepB) vaccination into the immunisation programmes of 11 'better-performing' Indian states. This article describes the concerns and interests of major stakeholders in the programme, including GAVI partners and the Indian government, and summarises Indian debates that have emerged in response to the project, especially on the issue of selective vs. universal immunisation. The article suggests that programme planning should be based on a good knowledge of disease prevalence and the relative importance of perinatal HepB transmission, which would require a comprehensive cross-country study of the epidemiology of HepB among different populations, the relative importance of different transmission routes and the degree of geographical variation in India. Based on this research, further studies could address the feasibility and cost-effectiveness of routine birth-dose administration and selective birth-dose immunisation of infants born to mothers who are chronic HepB virus carriers. The GAVI 'formula' could be strengthened by supporting the basic epidemiological research that is essential to effective programme planning in recipient countries, which are by definition among the world's poorest countries.

  2. GAVI and hepatitis B immunisation in India.

    PubMed

    Kolås, A

    2011-01-01

    In cooperation with Indian health authorities, the GAVI Alliance (GAVI) is introducing Hepatitis B (HepB) vaccination into the immunisation programmes of 11 'better-performing' Indian states. This article describes the concerns and interests of major stakeholders in the programme, including GAVI partners and the Indian government, and summarises Indian debates that have emerged in response to the project, especially on the issue of selective vs. universal immunisation. The article suggests that programme planning should be based on a good knowledge of disease prevalence and the relative importance of perinatal HepB transmission, which would require a comprehensive cross-country study of the epidemiology of HepB among different populations, the relative importance of different transmission routes and the degree of geographical variation in India. Based on this research, further studies could address the feasibility and cost-effectiveness of routine birth-dose administration and selective birth-dose immunisation of infants born to mothers who are chronic HepB virus carriers. The GAVI 'formula' could be strengthened by supporting the basic epidemiological research that is essential to effective programme planning in recipient countries, which are by definition among the world's poorest countries. PMID:20521193

  3. Gavi HPV Programs: Application to Implementation

    PubMed Central

    Hanson, Celina M.; Eckert, Linda; Bloem, Paul; Cernuschi, Tania

    2015-01-01

    Developing countries disproportionately suffer from the burden of cervical cancer yet lack the resources to establish systematic screening programs that have resulted in significant reductions in morbidity and mortality in developed countries. Human Papillomavirus (HPV) vaccination provides an opportunity for primary prevention of cervical cancer in low-resource settings through vaccine provision by Gavi The Vaccine Alliance. In addition to the traditional national introduction, countries can apply for a demonstration program to help them make informed decisions for subsequent national introduction. This article summarizes information from approved Gavi HPV demonstration program proposals and preliminary implementation findings. After two rounds of applications, 23 countries have been approved targeting approximately 400,000 girls for vaccination. All countries are proposing primarily school-based strategies with mixed strategies to locate and vaccinate girls not enrolled in school. Experiences to date include: Reaching marginalized girls has been challenging; Strong coordination with the education sector is key and overall acceptance has been high. Initial coverage reports are encouraging but will have to be confirmed in population based coverage surveys that will take place later this year. Experiences from these countries are consistent with existing literature describing other HPV vaccine pilots in low-income settings. PMID:26343194

  4. Origins, design and implementation of the China GAVI project.

    PubMed

    Liang, Xiaofeng; Cui, Fuqiang; Hadler, Stephen; Wang, Xiaojun; Luo, Huiming; Chen, Yuansheng; Kane, Mark; Shapiro, Craig; Yang, Weizhong; Wang, Yu

    2013-12-27

    China received GAVI support for hepatitis B vaccination in 2001 because of high disease burden and strong government will to protect infants at risk. The China/GAVI project, implemented since 2002, was funded 50% by GAVI and 50% by the Government of China. The purpose of the project was to increase coverage of hepatitis B vaccine through a pro-poor approach targeting all counties of the 12 Western provinces and poverty counties of the 10 Central provinces, to accelerate integration of hepatitis B vaccine into routine immunization, and assure immunization injection safety. The mechanism of internal coordination among multiple government entities and international cooperation was established and comprehensive strategies were used to improve vaccine coverage and injection safety. After 8 years of implementation, 193,000 health care workers in 118,316 health care facilities participated in the project, mostly at the township hospitals level (55,051) and in community centres (104,547). Through the China GAVI project, the 85% HepB3 coverage goal was reached in 98% of GAVI China project counties, the 75% timely birth dose (TBD) coverage goal was reached in 80% of GAVI project counties, and AD syringes were introduced into 100% of GAVI-supported areas. Additionally, the GAVI project was instrumental in convincing the Chinese Government to sustainably introduce and fully fund HepB vaccine for all newborns in China. The impact of hepB vaccination on HBsAg prevalence was observed throughout China, as HBsAg prevalence (previously ~10%) is now less than 1% among children under 5 years of age.

  5. Gavi's Transition Policy: Moving From Development Assistance To Domestic Financing Of Immunization Programs.

    PubMed

    Kallenberg, Judith; Mok, Wilson; Newman, Robert; Nguyen, Aurélia; Ryckman, Theresa; Saxenian, Helen; Wilson, Paul

    2016-02-01

    Gavi, the Vaccine Alliance, was created in 2000 to accelerate the introduction of new and underused vaccines in lower-income countries. The period 2000-15 was marked by the rapid uptake of new vaccines in more than seventy countries eligible for Gavi support. To stay focused on the poorest countries, Gavi's support phases out after countries' gross national income per capita surpasses a set threshold, which requires governments to assume responsibility for the continued financing of vaccines introduced with Gavi support. Gavi's funding will end in the period 2016-20 for nineteen countries that have exceeded the eligibility threshold. To avoid disrupting lifesaving immunization programs and to ensure the long-term sustainable impact of Gavi's investments, it is vital that governments succeed in transitioning from development assistance to domestic financing of immunization programs. This article discusses some of the challenges facing countries currently transitioning out of Gavi support, how Gavi's policies have evolved to help manage the risks involved in this process, and the lessons learned from this experience.

  6. Financial challenges of immunization: a look at GAVI.

    PubMed Central

    Kaddar, Miloud; Lydon, Patrick; Levine, Ruth

    2004-01-01

    Securing reliable and adequate public funding for prevention services, even those that are considered highly cost effective, often presents a challenge. This has certainly been the case with childhood immunizations in developing countries. Although the traditional childhood vaccines cost relatively little, funding in poor countries is often at risk and subject to the political whims of donors and national governments. With the introduction of newer and more costly vaccines made possible under the Global Alliance for Vaccines and Immunization (GAVI), the future financial challenges have become even greater. Experience so far suggests that choosing to introduce new combination vaccines can significantly increase the costs of national immunization programmes. With this experience comes a growing concern about their affordability in the medium term and long term and a realization that, for many countries, shared financial responsibility between national governments and international donors may initially be required. This article focuses on how GAVI is addressing the challenge of sustaining adequate and reliable funding for immunizations in the poorest countries. PMID:15628208

  7. Gavi's policy steers country ownership and self-financing of immunization.

    PubMed

    Henderson, Klara; Gouglas, Dimitrios; Craw, Laura

    2016-08-17

    This commentary examines the 2014 NIPH evaluation of Gavi's co-financing policy and comments on the appropriateness of the subsequent and most significant policy changes taking effect in 2016. PMID:27431423

  8. The GAVI Alliance and the 'Gates approach' to health system strengthening.

    PubMed

    Storeng, Katerini T

    2014-01-01

    Lauded for getting specific health issues onto national and international agendas and for their potential to improve value for money and outcomes, public-private global health initiatives (GHIs) have come to dominate global health governance. Yet, they have also been criticised for their negative impact on country health systems. In response, disease-specific GHIs have, somewhat paradoxically, appropriated the aim of health system strengthening (HSS). This article critically analyses this development through an ethnographic case study of the GAVI Alliance, which funds vaccines in poor countries. Despite GAVI's self-proclaimed 'single-minded' focus on vaccines, HSS support is fronted as a key principle of GAVI's mission. Yet, its meaning remains unclear and contested understandings of the health systems agenda abound, reflecting competing public health ideologies and professional pressures within the global health field. Contrary to broader conceptualisations of HSS that emphasise social and political dimensions, GAVI's HSS support has become emblematic of the so-called 'Gates approach' to global health, focused on targeted technical solutions with clear, measurable outcomes. In spite of adopting rhetoric supportive of 'holistic' health systems, GHIs like GAVI have come to capture the global debate about HSS in favour of their disease-specific approach and ethos.

  9. The GAVI Alliance and the 'Gates approach' to health system strengthening.

    PubMed

    Storeng, Katerini T

    2014-01-01

    Lauded for getting specific health issues onto national and international agendas and for their potential to improve value for money and outcomes, public-private global health initiatives (GHIs) have come to dominate global health governance. Yet, they have also been criticised for their negative impact on country health systems. In response, disease-specific GHIs have, somewhat paradoxically, appropriated the aim of health system strengthening (HSS). This article critically analyses this development through an ethnographic case study of the GAVI Alliance, which funds vaccines in poor countries. Despite GAVI's self-proclaimed 'single-minded' focus on vaccines, HSS support is fronted as a key principle of GAVI's mission. Yet, its meaning remains unclear and contested understandings of the health systems agenda abound, reflecting competing public health ideologies and professional pressures within the global health field. Contrary to broader conceptualisations of HSS that emphasise social and political dimensions, GAVI's HSS support has become emblematic of the so-called 'Gates approach' to global health, focused on targeted technical solutions with clear, measurable outcomes. In spite of adopting rhetoric supportive of 'holistic' health systems, GHIs like GAVI have come to capture the global debate about HSS in favour of their disease-specific approach and ethos. PMID:25156323

  10. The GAVI Alliance and the ‘Gates approach’ to health system strengthening

    PubMed Central

    Storeng, Katerini T.

    2014-01-01

    Lauded for getting specific health issues onto national and international agendas and for their potential to improve value for money and outcomes, public-private global health initiatives (GHIs) have come to dominate global health governance. Yet, they have also been criticised for their negative impact on country health systems. In response, disease-specific GHIs have, somewhat paradoxically, appropriated the aim of health system strengthening (HSS). This article critically analyses this development through an ethnographic case study of the GAVI Alliance, which funds vaccines in poor countries. Despite GAVI's self-proclaimed ‘single-minded’ focus on vaccines, HSS support is fronted as a key principle of GAVI's mission. Yet, its meaning remains unclear and contested understandings of the health systems agenda abound, reflecting competing public health ideologies and professional pressures within the global health field. Contrary to broader conceptualisations of HSS that emphasise social and political dimensions, GAVI's HSS support has become emblematic of the so-called ‘Gates approach’ to global health, focused on targeted technical solutions with clear, measurable outcomes. In spite of adopting rhetoric supportive of ‘holistic’ health systems, GHIs like GAVI have come to capture the global debate about HSS in favour of their disease-specific approach and ethos. PMID:25156323

  11. Contribution of the GAVI Alliance to improving health and reducing poverty.

    PubMed

    Lob-Levyt, Julian

    2011-10-12

    The Global Alliance for Vaccines and Immunization (GAVI), now 10 years old, was established as a successful and innovative public-private partnership to deal with a fundamental inequity. The poorest children in the poorest parts of the world were being denied access to life-saving vaccines simply on the basis of cost. GAVI has been successful in mobilizing significant funding from donors and through innovative financing instruments, immunizing large numbers of children. GAVI has been less successful, at least in the time frames first envisaged, at quickly reducing the prices of new and under-used vaccines to levels affordable by the poorest countries. Vaccines remain some of the most cost effective of public health interventions. As GAVI seeks to introduce a new set of vaccines to tackle major killers such as pneumonia and diarrhoea, and emerging threats such as cervical cancer, it needs to raise significant additional funds. There is no single solution. Multiple and new instruments will be required to raise finance both globally and at the country level, and also to incentivize industry and others to provide vaccines at affordable prices to the poorest countries. PMID:21893535

  12. Overcoming challenges to sustainable immunization financing: early experiences from GAVI graduating countries

    PubMed Central

    Hecht, Robert; Kaddar, Miloud; Schmitt, Sarah; Ryckman, Theresa; Cornejo, Santiago

    2015-01-01

    Over the 5-year period ending in 2018, 16 countries with a combined birth cohort of over 6 million infants requiring life-saving immunizations are scheduled to transition (graduate) from outside financial and technical support for a number of their essential vaccines. This support has been provided over the past decade by the GAVI Alliance. Will these 16 countries be able to continue to sustain these vaccination efforts? To address this issue, GAVI and its partners are supporting transition planning, entailing country assessments of readiness to graduate and intensive dialogue with national officials to ensure a smooth transition process. This approach was piloted in Bhutan, Republic of Congo, Georgia, Moldova and Mongolia in 2012. The pilot showed that graduating countries are highly heterogeneous in their capacity to assume responsibility for their immunization programmes. Although all possess certain strengths, each country displayed weaknesses in some of the following areas: budgeting for vaccine purchase, national procurement practices, performance of national regulatory agencies, and technical capacity for vaccine planning and advocacy. The 2012 pilot experience further demonstrated the value of transition planning processes and tools. As a result, GAVI has decided to continue with transition planning in 2013 and beyond. As the graduation process advances, GAVI and graduating countries should continue to contribute to global collective thinking about how developing countries can successfully end their dependence on donor aid and achieve self-sufficiency. PMID:24510369

  13. Contribution of the GAVI Alliance to improving health and reducing poverty.

    PubMed

    Lob-Levyt, Julian

    2011-10-12

    The Global Alliance for Vaccines and Immunization (GAVI), now 10 years old, was established as a successful and innovative public-private partnership to deal with a fundamental inequity. The poorest children in the poorest parts of the world were being denied access to life-saving vaccines simply on the basis of cost. GAVI has been successful in mobilizing significant funding from donors and through innovative financing instruments, immunizing large numbers of children. GAVI has been less successful, at least in the time frames first envisaged, at quickly reducing the prices of new and under-used vaccines to levels affordable by the poorest countries. Vaccines remain some of the most cost effective of public health interventions. As GAVI seeks to introduce a new set of vaccines to tackle major killers such as pneumonia and diarrhoea, and emerging threats such as cervical cancer, it needs to raise significant additional funds. There is no single solution. Multiple and new instruments will be required to raise finance both globally and at the country level, and also to incentivize industry and others to provide vaccines at affordable prices to the poorest countries.

  14. Contribution of the GAVI Alliance to improving health and reducing poverty

    PubMed Central

    Lob-Levyt, Julian

    2011-01-01

    The Global Alliance for Vaccines and Immunization (GAVI), now 10 years old, was established as a successful and innovative public–private partnership to deal with a fundamental inequity. The poorest children in the poorest parts of the world were being denied access to life-saving vaccines simply on the basis of cost. GAVI has been successful in mobilizing significant funding from donors and through innovative financing instruments, immunizing large numbers of children. GAVI has been less successful, at least in the time frames first envisaged, at quickly reducing the prices of new and under-used vaccines to levels affordable by the poorest countries. Vaccines remain some of the most cost effective of public health interventions. As GAVI seeks to introduce a new set of vaccines to tackle major killers such as pneumonia and diarrhoea, and emerging threats such as cervical cancer, it needs to raise significant additional funds. There is no single solution. Multiple and new instruments will be required to raise finance both globally and at the country level, and also to incentivize industry and others to provide vaccines at affordable prices to the poorest countries. PMID:21893535

  15. Post-GAVI sustainability of the Haemophilus influenzae type b vaccine program: The potential role of economic evaluation.

    PubMed

    Le, Phuc; Nghiem, Van T; Swint, J Michael

    2016-09-01

    Haemophilus influenzae type b (Hib) can cause severe invasive diseases which are, however, preventable by vaccination. To increase access to Hib vaccine, GAVI - the Vaccine Alliance - has provided financial support for 73 lower income countries worldwide. At the same time, GAVI has been implementing its co-financing policy, requiring recipient countries to pay a portion of vaccine costs and to increase this amount over time. Starting in 2016, 5 countries will stop receiving GAVI funding and procure the vaccine themselves. Although the graduating countries have access to the UNICEF/GAVI tendered vaccine price for 5 more years, the uncertainty in market vaccine price may hamper the post-GAVI program sustainability. A possible increase in vaccine price would cause a significant burden on governmental budgets, discouraging countries to continue the program. As a special tool, economic evaluation (EE) can assist decision makers by identifying the maximum affordable vaccine price for countries to pay. Given that only 6 GAVI-eligible countries have such analyses published, more EEs are necessary to strengthen countries' commitment during this transition period. The information will also be useful for manufacturers to determine their pricing policy.

  16. An analysis of how the GAVI alliance and low- and middle-income countries can share costs of new vaccines.

    PubMed

    Saxenian, Helen; Cornejo, Santiago; Thorien, Kira; Hecht, Robert; Schwalbe, Nina

    2011-06-01

    Immunization is one of the "best buys" in global health. However, for the poorest countries, even modest expenditures may be out of reach. The GAVI Alliance is a public-private partnership created to help the poorest countries introduce new vaccines. Since 2008 GAVI has required that countries cover a share of the cost of vaccines introduced with GAVI support. To determine how much countries can contribute to the cost of vaccines--without displacing spending on other essential programs--we analyzed their fiscal capacity to contribute to the purchase of vaccines over the coming decade. For low-income countries, external financing will be required to purchase vaccines supported by GAVI, so co-financing needs to be modest. Relatively better-off "intermediate" countries could support initially modest but gradually increasing co-financing levels. The countries soon to graduate from GAVI can generally afford to follow a rapid path to self-sufficiency. Co-financing for these countries needs to ramp up so that national budgets fully cover the costs of the new generation of vaccines once GAVI support ends.

  17. Post-GAVI sustainability of the Haemophilus influenzae type b vaccine program: The potential role of economic evaluation

    PubMed Central

    Le, Phuc; Nghiem, Van T.; Swint, J. Michael

    2016-01-01

    ABSTRACT Haemophilus influenzae type b (Hib) can cause severe invasive diseases which are, however, preventable by vaccination. To increase access to Hib vaccine, GAVI – the Vaccine Alliance – has provided financial support for 73 lower income countries worldwide. At the same time, GAVI has been implementing its co-financing policy, requiring recipient countries to pay a portion of vaccine costs and to increase this amount over time. Starting in 2016, 5 countries will stop receiving GAVI funding and procure the vaccine themselves. Although the graduating countries have access to the UNICEF/GAVI tendered vaccine price for 5 more years, the uncertainty in market vaccine price may hamper the post-GAVI program sustainability. A possible increase in vaccine price would cause a significant burden on governmental budgets, discouraging countries to continue the program. As a special tool, economic evaluation (EE) can assist decision makers by identifying the maximum affordable vaccine price for countries to pay. Given that only 6 GAVI-eligible countries have such analyses published, more EEs are necessary to strengthen countries' commitment during this transition period. The information will also be useful for manufacturers to determine their pricing policy. PMID:27135964

  18. Applying lessons learned from the USAID family planning graduation experience to the GAVI graduation process.

    PubMed

    Shen, Angela K; Farrell, Marguerite M; Vandenbroucke, Mary F; Fox, Elizabeth; Pablos-Mendez, Ariel

    2015-07-01

    As low income countries experience economic transition, characterized by rapid economic growth and increased government spending potential in health, they have increased fiscal space to support and sustain more of their own health programmes, decreasing need for donor development assistance. Phase out of external funds should be systematic and efforts towards this end should concentrate on government commitments towards country ownership and self-sustainability. The 2006 US Agency for International Development (USAID) family planning (FP) graduation strategy is one such example of a systematic phase-out approach. Triggers for graduation were based on pre-determined criteria and programme indicators. In 2011 the GAVI Alliance (formerly the Global Alliance for Vaccines and Immunizations) which primarily supports financing of new vaccines, established a graduation policy process. Countries whose gross national income per capita exceeds $1570 incrementally increase their co-financing of new vaccines over a 5-year period until they are no longer eligible to apply for new GAVI funding, although previously awarded support will continue. This article compares and contrasts the USAID and GAVI processes to apply lessons learned from the USAID FP graduation experience to the GAVI process. The findings of the review are 3-fold: (1) FP graduation plans served an important purpose by focusing on strategic needs across six graduation plan foci, facilitating graduation with pre-determined financial and technical benchmarks, (2) USAID sought to assure contraceptive security prior to graduation, phasing out of contraceptive donations first before phasing out from technical assistance in other programme areas and (3) USAID sought to sustain political support to assure financing of products and programmes continue after graduation. Improving sustainability more broadly beyond vaccine financing provides a more comprehensive approach to graduation. The USAID FP experience provides a

  19. Applying lessons learned from the USAID family planning graduation experience to the GAVI graduation process.

    PubMed

    Shen, Angela K; Farrell, Marguerite M; Vandenbroucke, Mary F; Fox, Elizabeth; Pablos-Mendez, Ariel

    2015-07-01

    As low income countries experience economic transition, characterized by rapid economic growth and increased government spending potential in health, they have increased fiscal space to support and sustain more of their own health programmes, decreasing need for donor development assistance. Phase out of external funds should be systematic and efforts towards this end should concentrate on government commitments towards country ownership and self-sustainability. The 2006 US Agency for International Development (USAID) family planning (FP) graduation strategy is one such example of a systematic phase-out approach. Triggers for graduation were based on pre-determined criteria and programme indicators. In 2011 the GAVI Alliance (formerly the Global Alliance for Vaccines and Immunizations) which primarily supports financing of new vaccines, established a graduation policy process. Countries whose gross national income per capita exceeds $1570 incrementally increase their co-financing of new vaccines over a 5-year period until they are no longer eligible to apply for new GAVI funding, although previously awarded support will continue. This article compares and contrasts the USAID and GAVI processes to apply lessons learned from the USAID FP graduation experience to the GAVI process. The findings of the review are 3-fold: (1) FP graduation plans served an important purpose by focusing on strategic needs across six graduation plan foci, facilitating graduation with pre-determined financial and technical benchmarks, (2) USAID sought to assure contraceptive security prior to graduation, phasing out of contraceptive donations first before phasing out from technical assistance in other programme areas and (3) USAID sought to sustain political support to assure financing of products and programmes continue after graduation. Improving sustainability more broadly beyond vaccine financing provides a more comprehensive approach to graduation. The USAID FP experience provides a

  20. Sustaining GAVI-supported vaccine introductions in resource-poor countries.

    PubMed

    Zuber, Patrick L F; El-Ziq, Ibrahim; Kaddar, Miloud; Ottosen, Ann E; Rosenbaum, Katinka; Shirey, Meredith; Kamara, Lidija; Duclos, Philippe

    2011-04-12

    Since 2000, GAVI provided essential support for an unprecedented increase in the use of hepatitis B (HepB) and Haemophilus influenzae (Hib) containing vaccines in resource poor countries. This increase was supported with significant funding from international donors, intended to be time-limited. To assess the sustainability of this important expansion of the global access to vaccines, we reviewed supply chains, financial resources for procurement and decision-making in countries that introduced hepatitis B or Hib vaccines with GAVI support. During the period studied, the types of vaccine products supplied fluctuated rapidly in relationship with the number of suppliers and availability of more combination products. The price of the cheaper vaccines decreased while that of pentavalent DTwP-HepB-Hib remained stable. In average, vaccine introduction was associated with an increase of national programs budget, with new vaccines representing more than half of that increase, while the part of GAVI contributions to the budget went from 25% to 46%. Less than 20% of the vaccine introductions were decided by a national advisory body. Strengthening supply chains, adjusting funding schemes and increasing national ownership will be key to the sustained use of hepatitis B and Hib vaccines and the eventual addition of other important vaccines where they are the most needed. PMID:21354249

  1. Sustaining GAVI-supported vaccine introductions in resource-poor countries.

    PubMed

    Zuber, Patrick L F; El-Ziq, Ibrahim; Kaddar, Miloud; Ottosen, Ann E; Rosenbaum, Katinka; Shirey, Meredith; Kamara, Lidija; Duclos, Philippe

    2011-04-12

    Since 2000, GAVI provided essential support for an unprecedented increase in the use of hepatitis B (HepB) and Haemophilus influenzae (Hib) containing vaccines in resource poor countries. This increase was supported with significant funding from international donors, intended to be time-limited. To assess the sustainability of this important expansion of the global access to vaccines, we reviewed supply chains, financial resources for procurement and decision-making in countries that introduced hepatitis B or Hib vaccines with GAVI support. During the period studied, the types of vaccine products supplied fluctuated rapidly in relationship with the number of suppliers and availability of more combination products. The price of the cheaper vaccines decreased while that of pentavalent DTwP-HepB-Hib remained stable. In average, vaccine introduction was associated with an increase of national programs budget, with new vaccines representing more than half of that increase, while the part of GAVI contributions to the budget went from 25% to 46%. Less than 20% of the vaccine introductions were decided by a national advisory body. Strengthening supply chains, adjusting funding schemes and increasing national ownership will be key to the sustained use of hepatitis B and Hib vaccines and the eventual addition of other important vaccines where they are the most needed.

  2. The inception, achievements, and implications of the China GAVI Alliance Project on Hepatitis B Immunization.

    PubMed

    Kane, M A; Hadler, S C; Lee, L; Shapiro, C N; Cui, F; Wang, X; Kumar, R

    2013-12-27

    The China GAVI Hepatitis B Immunization Project was initiated in 2002 with the signing of a Memorandum of Understanding between GAVI and the Government of China. The Project was one of the three (China, India, and Indonesia) GAVI-initiated special projects done to support countries too large to receive full GAVI support for hepatitis B vaccine and safe injections. The Project in China was designed by the Chinese Government and partners to deliver free hepatitis B vaccine and safe injections to all newborns in the 12 Western Provinces and Poverty Counties in 10 Provinces of Central China (1301 Counties with approximately 5.6 million births per year), eliminating the gap in immunization coverage between wealthier and poorer regions of China. The project budget (USD 76 million) was equally shared by GAVI and the Chinese Government. Initially planned for 5 years, two no cost extensions extended the project to 2011. Although China produced hepatitis B vaccine, before the project the vaccine was sold to parents who were also charged a "user fee" for the syringe and vaccine administration. Basic Expanded Program on Immunization (EPI) vaccines such as BCG, DTP, Polio, and measles vaccines were provided free to parents, although they were charged a user fee. Vaccines were sold by China CDC Offices at provincial, prefecture, county level and township hospitals, and village doctors received a substantial portion of their income from the sale of hepatitis B and other vaccines. The result of charging for hepatitis B vaccine was that coverage was relatively high in Eastern and wealthier counties in Central China (~80-90%), but was much lower (~40%) in Western China and Poverty Counties where parents could not afford the vaccine. The Project was administered by the China MOH and China CDC EPI program, and two Project Co-managers, one from the Chinese Government and the other an international assignee, were chosen. The project had an oversight Operational Advisory Group composed

  3. The inception, achievements, and implications of the China GAVI Alliance Project on Hepatitis B Immunization.

    PubMed

    Kane, M A; Hadler, S C; Lee, L; Shapiro, C N; Cui, F; Wang, X; Kumar, R

    2013-12-27

    The China GAVI Hepatitis B Immunization Project was initiated in 2002 with the signing of a Memorandum of Understanding between GAVI and the Government of China. The Project was one of the three (China, India, and Indonesia) GAVI-initiated special projects done to support countries too large to receive full GAVI support for hepatitis B vaccine and safe injections. The Project in China was designed by the Chinese Government and partners to deliver free hepatitis B vaccine and safe injections to all newborns in the 12 Western Provinces and Poverty Counties in 10 Provinces of Central China (1301 Counties with approximately 5.6 million births per year), eliminating the gap in immunization coverage between wealthier and poorer regions of China. The project budget (USD 76 million) was equally shared by GAVI and the Chinese Government. Initially planned for 5 years, two no cost extensions extended the project to 2011. Although China produced hepatitis B vaccine, before the project the vaccine was sold to parents who were also charged a "user fee" for the syringe and vaccine administration. Basic Expanded Program on Immunization (EPI) vaccines such as BCG, DTP, Polio, and measles vaccines were provided free to parents, although they were charged a user fee. Vaccines were sold by China CDC Offices at provincial, prefecture, county level and township hospitals, and village doctors received a substantial portion of their income from the sale of hepatitis B and other vaccines. The result of charging for hepatitis B vaccine was that coverage was relatively high in Eastern and wealthier counties in Central China (~80-90%), but was much lower (~40%) in Western China and Poverty Counties where parents could not afford the vaccine. The Project was administered by the China MOH and China CDC EPI program, and two Project Co-managers, one from the Chinese Government and the other an international assignee, were chosen. The project had an oversight Operational Advisory Group composed

  4. The Fazenda Gavião granodiorite and associated potassic plutons as evidence for Palaeoproterozoic arc-continent collision in the Rio Itapicuru greenstone belt, Brazil

    NASA Astrophysics Data System (ADS)

    Costa, Felipe G.; Oliveira, Elson P.; McNaughton, Neal J.

    2011-08-01

    Several granitic plutons have intruded the Palaeoproterozoic Rio Itapicuru greenstone belt, São Francisco craton, Brazil, in the time interval 2163-2080 Ma, but their tectonic significance is poorly understood. The Fazenda Gavião granodiorite (FGG) is one of a set of plutons emplaced along the western boundary of the greenstone belt with Archaean migmatite-gneiss basement. The pluton is mostly composed of hornblende granodiorite, occasionally crosscut by syn-plutonic mafic dykes. The FGG is metaluminous, medium- to high-K calc-alkaline with relatively constant silica abundances (SiO2 ˜ 63-66 wt%), high Sr (900-800 ppm) and high Ba (1000-1500 ppm). The associated mafic dykes are ultrapotassic, with high abundances of Ba, Sr, MgO, Ni, Cr, and light rare earth elements, suggesting derivation from partial melts of an enriched mantle source. The FGG originated probably by fractional crystallization from a primitive K-rich mafic magma that interacted with crustal melts. Its zircon U-Pb SHRIMP age of 2106 ± 6 Ma indicates that the FGG is younger than the early (2163-2127 Ma) tonalite-trondhjemite-granodiorite (TTG) and calc-alkaline arc plutons of the greenstone belt, and is closely related in time and space with potassic to ultrapotassic plutons (ca. 2110-2105 Ma). The negative ɛNd(t) of FGG and coeval K-rich plutons of the Rio Itapicuru greenstone belt contrasts markedly with the positive ɛNd(t) of the older arc plutons, indicating a major change of isotope signatures in granites of the Rio Itapicuru greenstone belt with time. This isotope shift may be related to magma contamination with older continental material and/or derivation of the parental potassic magma from enriched lithospheric mantle sources. We suggest that the K-rich plutons were emplaced during or shortly after Palaeoproterozoic arc-continent collision.

  5. GAViT: Genome Assembly Visualization Tool for Short Read Data

    SciTech Connect

    Syed, Aijazuddin; Shapiro, Harris; Tu, Hank; Pangilinan, Jasmyn; Trong, Stephan

    2008-03-14

    It is a challenging job for genome analysts to accurately debug, troubleshoot, and validate genome assembly results. Genome analysts rely on visualization tools to help validate and troubleshoot assembly results, including such problems as mis-assemblies, low-quality regions, and repeats. Short read data adds further complexity and makes it extremely challenging for the visualization tools to scale and to view all needed assembly information. As a result, there is a need for a visualization tool that can scale to display assembly data from the new sequencing technologies. We present Genome Assembly Visualization Tool (GAViT), a highly scalable and interactive assembly visualization tool developed at the DOE Joint Genome Institute (JGI).

  6. Global health partnerships in practice: taking stock of the GAVI Alliance's new investment in health systems strengthening.

    PubMed

    Naimoli, Joseph F

    2009-01-01

    Despite a burgeoning literature on global health partnerships (GHPs), there have been few studies of how GHPs, particularly those trying to build a bridge between horizontal and vertical modes of delivering essential health services, operate at global and country levels. This paper will help address this knowledge gap by describing and analyzing the GAVI Alliance's early experience with health systems strengthening (HSS) to improve immunization coverage and other maternal-child health outcomes. To date, the strengths of HSS reside in its potential to optimize GAVI's overall investment in immunization, efforts to harmonize with other initiatives, willingness to acknowledge risk and identify mitigation strategies, engagement of diverse stakeholders, responsiveness to country needs, and effective management of an ambitious grant-making enterprise. The challenges have been forging a common vision and approach, governance, balancing pressure to move money with incremental learning, managing partner roles and relationships, managing the "value for money" risk, and capacity building. This mid-point stock-taking makes recommendations for moving GAVI forward in a thoughtful manner. The findings should be of interest to other GHPs because of their larger significance. This is a story about how a successful alliance that decided to broaden its mandate has responded to the technical, organizational, and political complexities that challenge its traditional business model.

  7. Country Ownership And Gavi Transition: Comprehensive Approaches To Supporting New Vaccine Introduction.

    PubMed

    Shen, Angela K; Weiss, Jonathan M; Andrus, Jon Kim; Pecenka, Clint; Atherly, Deborah; Taylor, Katherine; McQuestion, Michael

    2016-02-01

    Since the mid-2000s low- and lower-middle-income countries have been focusing on developing and using evidence for immunization policy making, with an increasing emphasis on cost-effectiveness analysis, program costing, and financial flows-particularly for the introduction of newer, more expensive vaccines. While this is critical to informing decisions, countries still need to increase national immunization investment and explore innovative approaches to augment financing of immunization programs. The need for increased financing is especially strong in countries transitioning from support by Gavi, the Vaccine Alliance. With increased fiscal space to finance health and immunization programs as a result of improved economic performance, low- and lower-middle-income countries can reach the health status enjoyed by wealthier nations within a generation. However, new strategies and approaches related to domestic resources for immunization programs are needed to achieve this goal. Governments will need to increase their investments and modify existing external immunization financing arrangements if country ownership of immunization programs and the full promise of new vaccines are to be realized. PMID:26858380

  8. An analysis of GAVI, the Global Fund and World Bank support for human resources for health in developing countries.

    PubMed

    Vujicic, Marko; Weber, Stephanie E; Nikolic, Irina A; Atun, Rifat; Kumar, Ranjana

    2012-12-01

    Shortages, geographic imbalances and poor performance of health workers pose major challenges for improving health service delivery in developing countries. In response, multilateral agencies have increasingly recognized the need to invest in human resources for health (HRH) to assist countries in achieving their health system goals. In this paper we analyse the HRH-related activities of three agencies: the Global Alliance for Vaccines and Immunisation (GAVI); the Global Fund for Aids, Tuberculosis, and Malaria (the Global Fund); and the World Bank. First, we reviewed the type of HRH-related activities that are eligible for financing within each agency. Second, we reviewed the HRH-related activities that each agency is actually financing. Third, we reviewed the literature to understand the impact that GAVI, Global Fund and World Bank investments in HRH have had on the health workforce in developing countries. Our analysis found that by far the most common activity supported across all agencies is short-term, in-service training. There is relatively little investment in expanding pre-service training capacity, despite large health worker shortages in developing countries. We also found that the majority of GAVI and the Global Fund grants finance health worker remuneration, largely through supplemental allowances, with little information available on how payment rates are determined, how the potential negative consequences are mitigated, and how payments are to be sustained at the end of the grant period. Based on the analysis, we argue there is an opportunity for improved co-ordination between the three agencies at the country level in supporting HRH-related activities. Existing initiatives, such as the International Health Partnership and the Health Systems Funding Platform, could present viable and timely vehicles for the three agencies to implement this improved co-ordination.

  9. Key outcomes and addressing remaining challenges--perspectives from a final evaluation of the China GAVI project.

    PubMed

    Yang, Weizhong; Liang, Xiaofeng; Cui, Fuqiang; Li, Li; Hadler, Stephen C; Hutin, Yvan J; Kane, Mark; Wang, Yu

    2013-12-27

    During the China GAVI project, implemented between 2002 and 2010, more than 25 million children received hepatitis B vaccine with the support of project, and the vaccine proved to be safe and effective. With careful consideration for project savings, China and GAVI continually adjusted the budget, additionally allowing the project to spend operational funds to support demonstration projects to improve timely birth dose (TBD), conduct training of EPI staff, and to monitor the project impact. Results from the final evaluation indicated the achievement of key outcomes. As a result of government co-investment, human resources at county level engaged in hepatitis B vaccination increased from 29 per county on average in 2002 to 66 in 2009. All project counties funded by the GAVI project use auto-disable syringes for hepatitis B vaccination and other vaccines. Surveyed hepatitis B vaccine coverage increased from 71% in 2002 to 93% in 2009 among infants. The HBsAg prevalence declined from 9.67% in 1992 to 0.96% in 2006 among children under 5 years of age. However, several important issues remain: (1) China still accounts for the largest annual number of perinatal HBV infections (estimated 84,121) in the WHO WPR region; (2) China still lacks a clear national policy for safe injection of vaccines; (3) vaccination of high risk adults and protection of health care workers are still not implemented; (4) hepatitis B surveillance needs to be refined to more accurately monitor acute hepatitis B; and (5) a program for treatment of persons with chronic HBV infection is needed. Recommendations for future hepatitis B control include: using the lessons learned from the China GAVI project for future introductions of new vaccines; addressing unmet needs with a second generation hepatitis B program to reach every infant, including screening mothers, and providing HBIG for infants born to HBsAg positive mothers; expanding vaccination to high risk adults; addressing remaining unsafe

  10. Gates, GAVI, the glorious global funds and more: all you ever wanted to know.

    PubMed

    Nossal, Gustav J V

    2003-02-01

    Global immunization programmes have achieved some remarkable successes. In 1977, Frank Fenner's Commission declared smallpox to have been eradicated by an 11-year-long intensive campaign. The Expanded Programme on Immunization encompassed six important childhood vaccines and reached over three-quarters of the world's children. Polio eradication has gone remarkably well, with only 10 out of 200 countries reporting residual cases. But amidst all the good news, there is also bad news. Coverage is variable; infrastructure is crumbling; and newer vaccines are not being incorporated in many country programmes. The Bill and Melinda Gates Foundation has introduced a new dynamic here. From their initial gift of $100 million in December 1998, their commitment to date is US$1.5 billion - and rising. At the centre is a Global Children's Vaccine Fund which permitted the launch, in January 2000, of the Global Alliance for Vaccines and Immunization. This is targeted to the 74 poorest countries of the world and is designed to improve vaccination infrastructure, to purchase newer vaccines and to support research and development. Even before we know how successful this programme will be, it has had its imitators. The Global Fund to Fight AIDS, TB and Malaria borrowed many concepts from GAVI. The Global Alliance for Improved Nutrition announced in May 2002 does so as well, and is heavily supported by Gates. Highly effective parasite control programmes antedate all this but will be much strengthened. However, we still face a sizeable budgetary gap both for research and for bringing the best advances to all people who need them.

  11. The Caraguataí syenitic suite, a ca. 2.7 Ga-old alkaline magmatism (petrology, geochemistry and U-Pb zircon ages). Southern Gavião block (São Francisco Craton), Brazil

    NASA Astrophysics Data System (ADS)

    Cruz, Simone Cerqueira Pereira; Peucat, Jean-Jacques; Teixeira, Leo; Carneiro, Maurício Antônio; Marques Martins, Adriano Alberto; Santana, Jocilene dos Santos; de Souza, Jailma Santos; Barbosa, Johildo Salomão Figueiredo; Leal, Ângela Beatriz Menezes; Dantas, Elton; Pimentel, Marcio

    2012-08-01

    The Gavião Block comprises amphibolite- and granulite-facies gneisses and migmatites of tonalitic, granodioritic and granitic compositions and supracrustal sequences including volcanosedimentary layers metamorphosed up to the amphibolite facies. In the region of Abaíra-Jussiape (BA), two main igneous suites, called Caraguataí and Jussiape, are exposed in the core of an anticline. The Caraguataí suite encompasses alkali-feldspar granites, syenites and quartz syenites that contain biotite, magnetite/hematite, apatite, titanite, hastingsite/pargasite and zircon as accessory minerals that were adjusted to the amphibolite facies. White mica and epidote minerals are related to retrograde greenschist facies. These rocks were deformed in dextral to reverse-dextral shear zones, giving origin to protomylonites and augen-mesomylonites to ultramylonites. The ultramylonites have a prominent banding parallel to the main foliation of the rocks. Lithogeochemical studies revealed subalkaline to alkaline, metaluminous to peraluminous, Fe-rich protolith for instead of to these rocks associated with A2-type magmatism and partial melting of igneous continental crust. In situ U-Pb zircon dating using the Laser Ablation ICPMS method was carried out for five samples of the Caraguataí alkaline suite. The ages obtained for an isotropic syenite (SCP 1470: 2680 ± 24 Ma), a foliated syenite (SCP 2035: 2703 ± 11 Ma), a syenitic augen gneiss (SCP 2017: 2706 ± 34 Ma) and two ultramylonitic syenitic banded gneisses (SCP 1446: 2711 ± 34 Ma and SCP 1809: 2698 ± 10 Ma) fall in the same range. The average of the 62 concordant analyses obtained from the five samples allows to determine a mean 207Pb/206Pb age of 2696 ± 5 Ma (±2σ) interpreted as that of the alkaline plutonism. The geochronologic data obtained up to now have not helped to constrain an age for the metamorphism that affected the study area. The A2 type of magmatism, instead of and the TDM model ages (ca. 3.2-3.8 Ga) and the

  12. Perceptions of the usefulness of external support to immunization coverage in Chad: an analysis of the GAVI-Alliance cash-based support

    PubMed Central

    Ferrinho, Paulo; Dramé, Mohammed; Tumusiime, Prosper

    2013-01-01

    Introduction Chad is one of the countries supported by the GAVI-Alliance that remains with unsatisfactory vaccination coverage. This paper tries to understand the main barriers to better coverage. Methods These barriers were categorised as up or downstream against the health system building blocks as proposed by WHO and compared with barriers and activities identified by the country in its health system's strengthening grant proposal as approved by the GAVI Alliance in 2007. Data were collected using a modified Delphi system and by analysis of grant and annual report documents. Results Most of the activities anticipated under the GAVI health system's strengthening proposal are activities targeting downstream barriers (the neglect of upstream issues is of major importance in a decentralised state like Chad) and aligned with, not complementary to, immunization services strengthening activities. Further, both set of cash grants are blind to important recommendations such as the need to address barriers at the level of leadership and governance and at the level of the financing system and also about initiatives to promote community demand of vaccination services. Conclusion In Chad slow vaccination progress is aggravated by several contextual barriers: the size of the country, the low population density, the nomadic nature of a significant part of its peoples, the recent civil war, associated with civil unrest and political instability and its geographical localization. In this situation it would be important to sustain downstream operations (the major focus of the ISS grant) while taking a long term view of the needs of the health system. The GAVI effectively supports downstream operations, but neglects the long term view. PMID:24106572

  13. The Siderian-Orosirian magmatism in the Gavião Paleoplate, Brazil: U–Pb geochronology, geochemistry and tectonic implications

    NASA Astrophysics Data System (ADS)

    Pereira Cruz, Simone Cerqueira; Figueiredo Barbosa, Johildo Salomão; Pinto, Marilda Santos; Peucat, Jean-Jacques; Paquette, Jean Louis; Santos de Souza, Jailma; de Souza Martins, Violeta; Júnior, Farid Chemale; Carneiro, Mauricio Antonio

    2016-08-01

    The southern portion of the Gavião Paleoplate is composed by Archean orthogneisses, Archean-Paleoproterozoic metavolcano-sedimentary rocks and Siderian-Rhyacian-Orosirian granitoids. Petrographic, geochemical, U-Pb (Laser Ablation, ICPMS) and Sm-Nd data are presented for five Paleoproterozoic granitoids that were recently mapped: Jussiape II, Lagoa das Almas, Humaitá, Belo Campo and Broco granitoids. These granitoids present U-Pb zircon (LA-ICPMS) ages of 2052 ± 43, 2114 ± 24, 2140 ± 9, 2049 ± 23 and 2038 ± 8 Ma, respectively. In addition to these granitoids, another twenty-five ones were identified and studied by several authors, resulting in a total of twenty-nine plutons. Despite the previous petrography, geochemistry and geochronology studies that have been performed, no model had been proposed to explain the tectonic setting of this extensive granitogenesis. Integration of the new data and the literature has been done and corresponds to the second part of the article. Based on U-Pb dating and geochemical data, Siderian-Rhyacian-Orosirian granitoids of the southern Gavião Paleoplate were classified into five groups, or five suites: 1 (2324 ± 6 to 2091 ± 6.6 Ma), 2a (2054 -6/+8 to 2041 ± 23 Ma), 2b (2066 ± 37 to 2019 ± 32 Ma), 2c (2058 ± 8 to 1852 ± 50 Ma) and 2d (2049 ± 12 to 1929 ± 16 Ma). The granitoids of Group 1 present heterogeneous deformation, while the granitoids of groups 2a to 2d are generally not deformed. Usually the rocks are potassic, but sodic granitic rocks can be found in samples of groups 1, 2c and 2d. Several chemical classification parameters are presented and discussed herein, but it is noteworthy that the granitoids of Group 1 are mainly classified as calcic to calc-alkalic, while the rocks of the second group are mostly classified as alkalic ones. In the remaining groups, the samples vary between calc-alkalic and alkali-calcic. The εNd values range between 4.0 and -15.4 and suggest an important and varied share of the

  14. The Siderian-Orosirian magmatism in the Gavião Paleoplate, Brazil: U-Pb geochronology, geochemistry and tectonic implications

    NASA Astrophysics Data System (ADS)

    Pereira Cruz, Simone Cerqueira; Figueiredo Barbosa, Johildo Salomão; Pinto, Marilda Santos; Peucat, Jean-Jacques; Paquette, Jean Louis; Santos de Souza, Jailma; de Souza Martins, Violeta; Júnior, Farid Chemale; Carneiro, Mauricio Antonio

    2016-08-01

    The southern portion of the Gavião Paleoplate is composed by Archean orthogneisses, Archean-Paleoproterozoic metavolcano-sedimentary rocks and Siderian-Rhyacian-Orosirian granitoids. Petrographic, geochemical, U-Pb (Laser Ablation, ICPMS) and Sm-Nd data are presented for five Paleoproterozoic granitoids that were recently mapped: Jussiape II, Lagoa das Almas, Humaitá, Belo Campo and Broco granitoids. These granitoids present U-Pb zircon (LA-ICPMS) ages of 2052 ± 43, 2114 ± 24, 2140 ± 9, 2049 ± 23 and 2038 ± 8 Ma, respectively. In addition to these granitoids, another twenty-five ones were identified and studied by several authors, resulting in a total of twenty-nine plutons. Despite the previous petrography, geochemistry and geochronology studies that have been performed, no model had been proposed to explain the tectonic setting of this extensive granitogenesis. Integration of the new data and the literature has been done and corresponds to the second part of the article. Based on U-Pb dating and geochemical data, Siderian-Rhyacian-Orosirian granitoids of the southern Gavião Paleoplate were classified into five groups, or five suites: 1 (2324 ± 6 to 2091 ± 6.6 Ma), 2a (2054 -6/+8 to 2041 ± 23 Ma), 2b (2066 ± 37 to 2019 ± 32 Ma), 2c (2058 ± 8 to 1852 ± 50 Ma) and 2d (2049 ± 12 to 1929 ± 16 Ma). The granitoids of Group 1 present heterogeneous deformation, while the granitoids of groups 2a to 2d are generally not deformed. Usually the rocks are potassic, but sodic granitic rocks can be found in samples of groups 1, 2c and 2d. Several chemical classification parameters are presented and discussed herein, but it is noteworthy that the granitoids of Group 1 are mainly classified as calcic to calc-alkalic, while the rocks of the second group are mostly classified as alkalic ones. In the remaining groups, the samples vary between calc-alkalic and alkali-calcic. The ɛNd values range between 4.0 and -15.4 and suggest an important and varied share of the

  15. A new approach to global health institutions? A case study of new vaccine introduction and the formation of the GAVI Alliance.

    PubMed

    Sandberg, Kristin Ingstad; Andresen, Steinar; Bjune, Gunnar

    2010-10-01

    There is an emerging research agenda to analyse empirically the forces driving changes in global health governance. This study applies analytical tools from international relations research to explain the formation of international health regimes. The study utilizes two explanatory perspectives: individual leadership, and the interests of key non-state actors in the formation process, using the case of the formation of the Global Alliance for Vaccines and Immunization (GAVI) from 1995 to 1999. The case study is based on material from interviews with key actors, an archival review of documents from the Children's Vaccine Initiative (CVI), and published literature. Findings show that the regime formation process was initiated by individuals who were primarily affiliated to scientific communities and who led to the World Bank and the Gates Foundation becoming champions of a new coordinating mechanism for new vaccine introduction. Negotiations in the regime formation process were between a small group of founding agencies with divergent interests regarding immunization priorities. The case also sheds light on the authority of the WHO and the resources of the Gates Foundation in driving the process towards the final structure of the alliance. The paper discusses the potential contribution of the international relations approach compared to policy research as a way of understanding the institutional dynamics of global health, particularly in respect of relations between countries and non-state actors. PMID:20692756

  16. Coherent laser excitation of Ba-137 and Ba-138

    NASA Technical Reports Server (NTRS)

    Lam, Kai-Shue

    1992-01-01

    Computations are carried out for the 1S(6s2)-1P(6s,6p) coherent laser excitation of Ba-137 and Ba-138 in a magnetic field. Results are presented for both the steady-state and time-dependent excited-state populations of the Zeeman-split magnetic sublevels. The quantum-statistical Liouville-equation approach (for the reduced density matrix) is compared to the rate-equations approach. Significant differences are found between these, due to the interference between strongly overlapping lines (especially for Ba-137). The time-evolution profiles indicate that the Ba-137 transient time is much longer than that of Ba-138.

  17. Band-overlap metallization of BaS, BaSe and BaTe

    NASA Technical Reports Server (NTRS)

    Carlsson, A. E.; Wilkins, J. W.

    1983-01-01

    The insulator-metal transition volumes for BaS, BaSe, and BaTe are calculated for the first time, using the self-consistent augmented spherical wave technique. The metallized transition volumes are smaller than those corresponding to the NaCl yields CsCl structural transitions, but, 10 to 15% larger than those obtained by the Herzfeld dielectric theory. The calculated equilibrium energy gaps in the NaCl structure underestimate the measured ones by 50 to 60%.

  18. Ba isotopic signature for early differentiation between Cs and Ba in natural fission reactors

    NASA Astrophysics Data System (ADS)

    Hidaka, Hiroshi; Gauthier-Lafaye, François

    2008-08-01

    Ba isotopic studies of the Oklo and Bangombé natural fission reactors in east Gabon provide information on the geochemical behavior of radioactive Cs ( 135Cs and 137Cs) in a geological medium. Large isotopic deviations derived from fissiogenic Ba were found in chemical leachates of the reactor uraninites. The fissiogenic Ba isotopic patterns calculated by subtracting the non-fissiogenic component are classified into three types that show different magnifications of chemical fractionation between Cs and Ba. In addition, the isotopic signatures of fissiogenic 135Ba, 137Ba and 138Ba suggest an early differentiation between Cs and Ba of less than 20 years after the production of fissiogenic Cs and Ba. On the other hand, only small excesses of 135Ba ( ɛ < +1.8) and/or 137Ba ( ɛ < +1.3) were identified in some clay samples, which might have resulted from selective adsorption of 135Cs and 137Cs that migrated from the reactors by differentiation.

  19. Electronic and Optical Properties of BaO, BaS, BaSe, BaTe and BaPo Compounds Under Hydrostatic Pressure

    NASA Astrophysics Data System (ADS)

    Drablia, S.; Meradji, H.; Ghemid, S.; Boukhris, N.; Bouhafs, B.; Nouet, G.

    We have performed first-principle full-potential (linear) augmented plane wave plus local orbital calculations (FP-L/APW + l0) with density functional theory (DFT) in local density approximation (LDA) and generalized gradient approximation (GGA), with the aim to determine and predict the electronic and optical properties of rocksalt BaO, BaS, BaSe, BaTe and BaPo compounds. First we present the main features of the electronic properties of these compounds, where the electronic band structure shows that the fundamental energy gap is indirect (Γ-X) for all compounds except for BaO which is direct (X-X). The different interband transitions have been determined from the imaginary part of the dielectric function. The real and imaginary parts of the dielectric function and the reflectivity are calculated. We have presented the assignment of the different optical transitions existing in these compounds from the imaginary part of the dielectric function spectra with respect to their correspondence in the electronic band. We have also calculated the pressure and volume dependence of the optical properties for these compounds.

  20. Toward the Validation of Ba.

    ERIC Educational Resources Information Center

    Burton, Craig L.; Schwen, Thomas M.

    2003-01-01

    The theory of "ba" or "space" offers a prescription for fostering the conversion of particular kinds of knowledge (tacit-to-explicit, tacit-to-tacit, etc.). Three corporate groups were observed as they collaborated to develop instructional, Web-based stories intended to capture their tacit organizational understandings. A comparative case study…

  1. Phase formation in the BaB2O4-BaF2 system

    NASA Astrophysics Data System (ADS)

    Bekker, T. B.; Fedorov, P. P.; Kokh, A. E.

    2012-07-01

    It is shown that the BaB2O4-BaF2 system is quasi-binary with the following eutectics coordinates: 760°C, 59 mol % BaF2, 41 mol % BaB2O4. Due to the intense pyrohydrolysis during the growth of β-BaB2O4 crystals from the 55.6 mol % BaB2O4-44.4 mol % BaF2 composition, the Ba5B4O11 compound is formed in the system. This process leads to the cocrystallization of the β-BaB2O4 and Ba5B4O11 phases and impedes the formation of high-quality crystals.

  2. Thermoluminescence properties of nanophosphors BaSO₄:Dy and BaSO₄:Tb.

    PubMed

    Rezaee Ebrahim Saraee, Kadijeh; Aghay Kharieky, Amin

    2013-12-01

    Nanocrystalline BaSO4:Dy and BaSO4:Tb were prepared by the coprecipitation method. The materials were characterized with X-ray diffractometry, UV-visible spectroscopy, and scanning electron microscopy. The glow curves of the BaSO4:Dy and BaSO4:Tb nanophosphors feature main peaks at 505 K and 480 K, respectively. The responses to the (60)Co dose are linear in the range 0.1-1 kGy for BaSO4:Dy and in the range 0.1-7 kGy for BaSO4:Tb. The energy dependences of the responses were also studied.

  3. Evolution of octupole correlations in 123Ba

    NASA Astrophysics Data System (ADS)

    Chen, X. C.; Zhao, J.; Xu, C.; Hua, H.; Shneidman, T. M.; Zhou, S. G.; Wu, X. G.; Li, X. Q.; Zhang, S. Q.; Li, Z. H.; Liang, W. Y.; Meng, J.; Xu, F. R.; Qi, B.; Ye, Y. L.; Jiang, D. X.; Cheng, Y. Y.; He, C.; Sun, J. J.; Han, R.; Niu, C. Y.; Li, C. G.; Li, P. J.; Wang, C. G.; Wu, H. Y.; Li, Z. H.; Zhou, H.; Hu, S. P.; Zhang, H. Q.; Li, G. S.; He, C. Y.; Zheng, Y.; Li, C. B.; Li, H. W.; Wu, Y. H.; Luo, P. W.; Zhong, J.

    2016-08-01

    High-spin states of 123Ba have been studied via the 108Cd(19F,3 n p )123Ba fusion-evaporation reaction at a beam energy of 90 MeV. Several E 1 transitions linking the positive-parity ν (d5 /2+g7 /2) band and negative-parity ν h11 /2 band are observed in 123Ba for the first time. Evidence for the existence of octupole correlations in 123Ba is presented based on the systematic comparisons of the B (E 1 )/B (E 2 ) branching ratios and the energy displacements in odd-A Ba isotopes. The characteristics of octupole correlation in the odd-A Ba,125123 are explained by the state-of-the-art multidimensionally-constrained relativistic mean-field model and cluster model based on the dinuclear system concept.

  4. Anomalous magnetic moment at Ba in Au

    NASA Astrophysics Data System (ADS)

    Bhati, A. K.; Kaur, J.; Bansal, N.; Negi, D.; Kumar, R.; Bhowmik, R. K.; Kumar, V.; Dey, C. C.

    2015-04-01

    The Time differential perturbed angular distribution (TDPAD) technique is employed to measure the local susceptibility at the recoil implanted Ba ions in Au following the nuclear reaction 120Sn(12C, 3nγ)129Ba. We have observed first time the local paramagnetic susceptibility of 5.26(18) at Ba ions comparable to 4f-ions in any non-ferromagnetic metal at room temperature which seems to be related to the electronic s-d and s-f transfer at positive lattice pressure.

  5. Syntheses, crystal structure, and electronic properties of the five ABaMQ4 compounds RbBaPS4, CsBaPS4, CsBaVS4, RbBaVSe4, and CsBaVSe4

    NASA Astrophysics Data System (ADS)

    Mesbah, Adel; Prakash, Jai; Rocca, Dario; Lebègue, Sébastien; Beard, Jessica C.; Lewis, Benjamin A.; Ibers, James A.

    2016-01-01

    Five new compounds belonging to the ABaMQ4 family were synthesized by solid-state chemistry at 1123 K. The compounds RbBaPS4, CsBaPS4, CsBaVS4, RbBaVSe4, and CsBaVSe4 are isostructural and have the TlEuPS4 structure type. They crystallize in space group D162h - Pnma of the orthorhombic system. Their structure consists isolated MQ4 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 (RbBaPS4), 3.4 eV (CsBaPS4), 2.3 eV (CsBaVS4), and 1.6 eV (RbBaVSe4).

  6. THE DIRC Detector at BaBar

    SciTech Connect

    Ratcliff, Blair N

    1999-10-12

    A dedicated particle identification system based on the Detection of Internally Reflected Cherenkov (DIRC) light will be used in the BaBar detector. We provide an overview of the DIRC concept, design, and expected performance of the production device and a status report on its construction and commissioning. The DIRC is expected to be operating in the BaBar detector on beam line at the PEP-II B Factory in late spring 1999.

  7. AMiBA First SZ Measurements

    NASA Astrophysics Data System (ADS)

    Lin, K.-Y.; Wu, J.-H. P.; Umetsu, K.; Kock, P.; Liu, G.-C.; Nishioka, H.; Huang, C.-W.; Liao, Y.-W.; Wang, F.-C.; Ho, P.

    2008-10-01

    Y.T.Lee Array for Microwave Background Anisotropy (AMiBA) is an array utilizing the 90GHz band to measure the CMB power spectrum and the Sunyaev-Zeldovich effect of galaxy clusters. The first stage with seven antennae has been completed, and the second stage with thirteen antennae is being constructed. Using the seven-element array, AMiBA has performed observations on six massive galaxy clusters at redshifts 0.09 - 0.32 during 2007.

  8. Changes in Ba phases in BaO/Al₂O₃ upon thermal aging and H₂O treatment

    SciTech Connect

    Kim, Do Heui; Chin, Ya-Huei; Kwak, Ja Hun; Szanyi, Janos; Peden, Charles HF

    2005-12-01

    The effects of thermal aging and H₂O treatment on the physicochemical properties of a BaO/Al₂O₃ model catalyst were investigated by means of XRD, BET, TEM/EDX and NO₂ TPD. Thermal aging at 1000 °C for 10 hrs resulted in conversion of dispersed BaCO₃ into low surface area crystalline BaAl₂O₄. It was found that H₂O treatment on a BaO/Al₂O₃ sample at room temperature transformed not only the BaAl₂O₄, but also the dispersed BaCO₃ into highly crystalline BaCO₃ segregated from the Al₂O₃ support, as evidenced in TEM/EDX and XRD analysis. The sample containing dispersed BaCO3 in the initial phase segregated more severely than the BaAl₂O₄ containing one, with the Ba in the BaAl₂O₄ matrix exhibiting higher resistance towards segregation. Contacting the BaO/Al₂O₃ sample with liquid water over a prolong period of time leads to an increase in crystallinity of the segregated BaCO₃. These phenomena imply that special care must be taken during catalyst synthesis and during realistic operation of Pt/BaO/Al₂O₃ NOx trap catalysts since both processes involve potential exposure of the material with liquid H₂O. Based on the results, a model to explain the behavior of Ba containing species upon thermal aging and H₂O treatment is proposed.

  9. Incorporation of Ba in Al and Fe pollucite

    NASA Astrophysics Data System (ADS)

    Vance, Eric R.; Gregg, Daniel J.; Griffiths, Grant J.; Gaugliardo, Paul R.; Grant, Charmaine

    2016-09-01

    Ba, the transmutation product of radioactive Cs, can be incorporated at levels of up to ∼0.07 formula units in Cs(1-2x)BaxAlSi2O6 aluminium pollucite formed by sol-gel methods and sintering at 1400 °C, with more Ba forming BaAl2Si2O8 phases. The effect of Ba substitution in pollucite-structured CsFeSi2O6 was also studied and no evidence of Ba substitution in the pollucite structure via cation vacancies or Fe2+ formation was obtained. The Ba entered a Fe-silicate glass structure. Charge compensation was also attempted with a Cs+ + Fe3+ ↔ Ba2+ + Ni2+ scheme but again the Ba formed a glass and NiO was evident. PCT leaching data showed CsFeSi2O6 to be very leach resistant.

  10. Transition probabilities in the X(5) candidate {sup 122}Ba

    SciTech Connect

    Bizzeti, P. G.; Giannatiempo, A.; Perego, A.; Bizzeti-Sona, A. M.; Tonev, D.; Petkov, P.; Ur, C. A.; Bazzacco, D.; Farnea, E.; Marginean, R.; Menegazzo, R.; Alvarez, C. Rossi; Dewald, A.; Melon, B.; Fransen, C.; Moeller, O.; Costin, A.; Pietralla, N.; De Angelis, G.; Vedova, F. Della

    2009-01-28

    The lifetimes of excited states of the {sup 122}Ba ground--state band, populated via the {sup 108}Cd({sup 16}O,2n){sup 122}Ba and the {sup 112}Sn({sup 13}C,2n){sup 122}Ba reactions, have been measured using the Recoil Distance Doppler--Shift method. The level scheme of {sup 122}Ba has also been revised.

  11. Benzo[a]pyrene (BaP)

    Integrated Risk Information System (IRIS)

    Benzo [ a ] pyrene ( BaP ) ; CASRN 50 - 32 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarc

  12. Unitarity Triangles at BaBar

    SciTech Connect

    Martinez-Vidal, Fernando; /Valencia U., IFIC

    2011-11-23

    The BaBar experiment has used a variety of methods to determine the angles {alpha}, {beta}, and {gamma} of the Cabibbo-Kobayashi-Maskawa Unitarity Triangle, which give insight into the Standard Model description of CP violation in the quark sector of the electroweak interactions. Here we review the main experimental techniques and analyses, with emphasis in the most recent results.

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

    NASA Technical Reports Server (NTRS)

    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

  14. Cu/Ba/bauxite: an Inexpensive and Efficient Alternative for Pt/Ba/Al2O3 in NOx Removal

    PubMed Central

    Wang, Xiuyun; Chen, Zhilin; Luo, Yongjin; Jiang, Lilong; Wang, Ruihu

    2013-01-01

    Cu/Ba/bauxite possesses superior NOx storage and reduction (NSR) performances, high thermal stability, strong resistance against SO2 poisoning and outstanding regeneration ability in comparison with Pt/Ba/Al2O3. It can serve as a cheap and promising alternative for traditional Pt/Ba/Al2O3 in NOx removal from lean-burn engines. PMID:23536149

  15. Cu/Ba/bauxite: an inexpensive and efficient alternative for Pt/Ba/Al₂O₃ in NOx removal.

    PubMed

    Wang, Xiuyun; Chen, Zhilin; Luo, Yongjin; Jiang, Lilong; Wang, Ruihu

    2013-01-01

    Cu/Ba/bauxite possesses superior NOx storage and reduction (NSR) performances, high thermal stability, strong resistance against SO₂ poisoning and outstanding regeneration ability in comparison with Pt/Ba/Al₂O₃. It can serve as a cheap and promising alternative for traditional Pt/Ba/Al₂O₃ in NOx removal from lean-burn engines.

  16. Different roles of cytoarchitectonic BA 44 and BA 45 in phonological and semantic verbal fluency as revealed by dynamic causal modelling.

    PubMed

    Heim, Stefan; Eickhoff, Simon B; Amunts, Katrin

    2009-11-15

    The interactions of left cytoarchitectonic BA 44 and BA 45 during semantic and phonological verbal fluency tasks were investigated using dynamic causal modelling (DCM). Three different models were tested, all of which featured BA 44 and BA 45 as top-down driven interconnected nodes projecting to the motor cortex as the final output region. Model #1 represents the hypothesis that BA 45 is involved in lexical retrieval including both semantic and phonological processes, while BA 44 supports other phonological processes. Model #2 reflects the notion of a clear-cut segregation of computational processes sustained by BA 44 (phonological processing) and BA 45 (semantic processing). Model #3 was based on the hypothesis that both BA 44 and BA 45 support semantic and phonological processing. When these models were compared against each other by Bayesian model selection, evidence emerged in favour of the first model, implying that BA 45 supports word retrieval processes whereas BA 44 is involved in processing phonological information during word generation. In a subsequent analysis of the derived model parameters for model #1, all connection strengths were significantly positive except for the inhibitory coupling between BA 44 and BA 45. This inhibition may reflect how the phonological analysis in BA 44 during word generation constrains lexical word retrieval in BA 45. To conclude, DCM provided additional insights into the roles of BA 44 and BA 45 during verbal fluency revealing the involvement of BA 45 in lexical retrieval and the relevance of BA 44 for phonological processing during word generation. PMID:19560543

  17. Electronic structure and structural phase stability in BaS, BaSe, and BaTe

    NASA Astrophysics Data System (ADS)

    Kalpana, G.; Palanivel, B.; Rajagopalan, M.

    1994-11-01

    The self-consistent scalar-relativistic band structures for BaS, BaSe, and BaTe in NaCl-type and CsCl-type structures were obtained using the tight-binding linear muffin-tin orbital method. From atomic-sphere approximation (ASA) total-energy calculations the structural phase stability in these compounds has been studied. The equilibrium lattice constant for all three compounds agrees well with the experimental results. The pressures at which these compounds undergo a structural phase transition from NaCl-type to CsCl-type were calculated. The calculated pressures and volumes at transition agree well with the experimental results. The energy band gaps at ambient conditions in the NaCl-type structure and the volume dependence of band gaps in the CsCl-type structure were calculated. In addition the pressures and the volumes at which band overlap metallization occurs were also calculated and compared with experimental and other theoretical results.

  18. Crystal Structure and Thermodynamic Stability of Ba/Ti-Substituted Pollucites for Radioactive Cs/Ba Immobilization

    DOE PAGES

    Xu, Hongwu; Chavez, Manuel E.; Mitchell, Jeremy N.; Garino, Terry J.; Schwarz, Haiqing L.; Rodriguez, Mark A.; Rademacher, David X.; Nenoff, Tina Maria

    2015-04-23

    An analogue of the mineral pollucite (CsAlSi2O6), CsTiSi2O6.5 has a potential host phase for radioactive Cs. However, as 137Cs and 135Cs transmute to 137Ba and 135Ba, respectively, through the beta decay, it is essential to study the structure and stability of this phase upon Cs → Ba substitution. In this work, two series of Ba/Ti-substituted samples, CsxBa(1-x)/2TiSi2O6.5 and CsxBa1-xTiSi2O7-0.5x, (x = 0.9 and 0.7), were synthesized by high-temperature crystallization from their respective precursors. Synchrotron X-ray diffraction and Rietveld analysis reveal that while CsxBa(1-x)/2TiSi2O6.5 samples are phase-pure, CsxBa1-xTiSi2O7-0.5x samples contain Cs3x/(2+x)Ba(1-x)/(2+x)TiSi2O6.5 pollucites (i.e., also two-Cs-to-one-Ba substitution) and a secondary phase, fresnoitemore » (Ba2TiSi2O8). Thus, the CsxBa1-xTiSi2O7-0.5x series is energetically less favorable than CsxBa(1-x)/2TiSi2O6.5. To study the stability systematics of CsxBa(1-x)/2TiSi2O6.5 pollucites, high-temperature calorimetric experiments were performed at 973 K with or without the lead borate solvent. Enthalpies of formation from the constituent oxides (and elements) have thus been derived. Our results show that with increasing Ba/(Cs + Ba) ratio, the thermodynamic stability of these phases decreases with respect to their component oxides. Hence, from the energetic viewpoint, continued Cs → Ba transmutation tends to destabilize the parent silicotitanate pollucite structure. However, the Ba-substituted pollucite co-forms with fresnoite (which incorporates the excess Ba), thereby providing viable ceramic waste forms for all the Ba decay products.« less

  19. Molecular evolution of the hypervariable region of the attachment glycoprotein gene in human respiratory syncytial virus subgroup B genotypes BA9 and BA10.

    PubMed

    Nagasawa, Koo; Hirano, Eiko; Kobayashi, Miho; Ryo, Akihide; Oishi, Kazunori; Obuchi, Masatsugu; Ishiwada, Naruhiko; Noda, Masahiro; Kuroda, Makoto; Shimojo, Naoki; Kimura, Hirokazu

    2015-12-01

    We studied the molecular evolution of the C-terminal 3rd hypervariable region in the attachment glycoprotein gene of human respiratory syncytial virus subgroup B (HRSV-B) genotypes BA9 and BA10. We performed time-scaled phylogenetic analyses using Bayesian Markov chain Monte Carlo methods. We also performed a genetic distance analysis (p-distance analysis), positive and negative selection analyses, and a Bayesian skyline plot (BSP) analysis. We found that genotype BA9 diverged from the common ancestor of genotypes BA7, BA8, and BA10, while genotype BA10 diverged from the ancestor of genotypes BA7 and BA8. Strains of both genotypes were distributed worldwide. BA9 and BA10 diverged between 1999 and 2001. Both BA9 and BA10 evolved rapidly (about 4.8×10(-3)substitutions/site/year) and formed three distinct lineages in a 10-year period. BA10 strains belonging to lineage 3 had large genetic distances (p-distance>0.07). Thus, it may be possible to classify these strains as a new genotype, BA11. No positive selection site was detected in either genotype. Phylodynamic analyses showed that the effective population size of BA10 decreased gradually since 2010 and BA9 slightly decreased since 2009. The results suggested that the recently prevalent HRSV-B genotypes BA9 and BA10 evolved uniquely, leading to epidemics of HRSV-B worldwide over a 15-year period. PMID:26408340

  20. The AMiBA Hexapod Telescope Mount

    NASA Astrophysics Data System (ADS)

    Koch, Patrick M.; Kesteven, Michael; Nishioka, Hiroaki; Jiang, Homin; Lin, Kai-Yang; Umetsu, Keiichi; Huang, Yau-De; Raffin, Philippe; Chen, Ke-Jung; Ibañez-Romano, Fabiola; Chereau, Guillaume; Huang, Chih-Wei Locutus; Chen, Ming-Tang; Ho, Paul T. P.; Pausch, Konrad; Willmeroth, Klaus; Altamirano, Pablo; Chang, Chia-Hao; Chang, Shu-Hao; Chang, Su-Wei; Han, Chih-Chiang; Kubo, Derek; Li, Chao-Te; Liao, Yu-Wei; Liu, Guo-Chin; Martin-Cocher, Pierre; Oshiro, Peter; Wang, Fu-Cheng; Wei, Ta-Shun; Wu, Jiun-Huei Proty; Birkinshaw, Mark; Chiueh, Tzihong; Lancaster, Katy; Lo, Kwok Yung; Martin, Robert N.; Molnar, Sandor M.; Patt, Ferdinand; Romeo, Bob

    2009-04-01

    The Array for Microwave Background Anisotropy (AMiBA) is the largest hexapod astronomical telescope in current operation. We present a description of this novel hexapod mount with its main mechanical components—the support cone, universal joints, jack screws, and platform—and outline the control system with the pointing model and the operating modes that are supported. The AMiBA hexapod mount performance is verified based on optical pointing tests and platform photogrammetry measurements. The photogrammetry results show that the deformations in the inner part of the platform are less than 120 μm rms. This is negligible for optical pointing corrections, radio alignment, and radio phase errors for the currently operational seven-element compact configuration. The optical pointing error in azimuth and elevation is successively reduced by a series of corrections to about 0farcm 4 rms which meets our goal for the seven-element target specifications.

  1. Simulation of BaBar Drift Chamber

    SciTech Connect

    Anderson, Rachel; /Wisconsin U., Eau Claire /SLAC

    2006-09-27

    The BaBar drift chamber (DCH) is used to measure the properties of charged particles created from e{sup +}e{sup -} collisions in the PEP-II asymmetric-energy storage rings by making precise measurements of position, momentum and ionization energy loss (dE/dx). In October of 2005, the PEP-II storage rings operated with a luminosity of 10 x 10{sup 33} cm{sup -2}s{sup -1}; the goal for 2007 is a luminosity of 20 x 10{sup 33} cm{sup -2}s{sup -1}, which will increase the readout dead time, causing uncertainty in drift chamber measurements to become more significant in physics results. The research described in this paper aims to reduce position and dE/dx uncertainties by improving our understanding of the BaBar drift chamber performance. A simulation program--called GARFIELD--is used to model the behavior of the drift chamber with adjustable parameters such as gas mixture, wire diameter, voltage, and magnetic field. By exploring the simulation options offered in GARFIELD, we successfully produced a simulation model of the BaBar drift chamber. We compared the time-to-distance calibration from BaBar to that calculated by GARFIELD to validate our model as well as check for discrepancies between the simulated and calibrated time-to-distance functions, and found that for a 0{sup o} entrance angle there is a very good match between calibrations, but at an entrance angle of 90{sup o} the calibration breaks down. Using this model, we also systematically varied the gas mixture to find one that would optimize chamber operation, which showed that the gas mixture of 80:20 Helium:isobutane is a good operating point, though more calculations need to be done to confirm that it is the optimal mixture.

  2. Hadron Physics in BaBar

    SciTech Connect

    Lafferty, G.D.; /Manchester U.

    2005-08-29

    Some recent results in hadron physics from the BaBar experiment are discussed. In particular, the observation of two new charmed states, the D*{sub sJ}{sup +}(2317) and the D*{sub sJ}{sup +}(2457), is described, and results are presented on the first measurement of the rare decay mode of the B meson, B{sup 0} {pi}{sup 0}{pi}{sup 0}.

  3. The thermodynamic behavior of sulfur in BaO-BaF2 slags

    NASA Astrophysics Data System (ADS)

    Rachev, Ivan P.; Tsukihashi, Fumitaka; Sano, Nobuo

    1991-06-01

    A gas-slag-metal equilibration technique was used to determine the sulfide capacity of the BaO-BaF2 system at 1473 and 1573 K. The dependence of carbonate capacity on the slag composition was also measured at these temperatures. It was found that the BaO-BaF2 system has the highest sulfide capacities among the fluxes which are of metallurgical interest. The dependence of sulfide and carbonate capacities on the partial pressure of O2 and CO2 was also investigated. The partial pressure of CO2 proved to have a strong effect on these values at the investigated temperatures. The influence of temperature on the sulfide and carbonate capacities was studied in the temperature range between 1423 and 1623 K. The data for sulfide and carbonate capacities were correlated in order to check if the carbonate capacity can be used as a measure of basicity of slags. It was found that the carbonate capacity can be used as a representative measure of the slag basicity at low contents of BaO and at temperatures higher than 1623 K when the carbonate dissolution into the slag is low and the ratio of the activity coefficient of a sulfide ion to that of a carbonate ion is independent of slag composition.

  4. Topological phases in Ba-Borate glasses

    NASA Astrophysics Data System (ADS)

    Holbrook, Chad; Czaja, Andrew; Boolchand, Punit

    2015-03-01

    Twelve compositions in the (BaO)x(B2O3)100-x pseudo binary, in the 15% BaCO3, taking care to handle the materials in a dry ambient environment. 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 <24% are in the stressed-rigid phase, in the 24% 30% in the flexible phase. Supported by NSF Grant DMR 08-53957.

  5. Structure refinement and dielectric relaxation of M-type Ba, Sr, Ba-Sr, and Ba-Pb hexaferrites

    NASA Astrophysics Data System (ADS)

    Ashima; Sanghi, Sujata; Agarwal, Ashish; Reetu; Ahlawat, Neetu; Monica

    2012-07-01

    M-type hexaferrites with compositions BaFe12O19 (BFO), SrFe12O19 (SFO), Ba0.5Sr0.5Fe12O19 (BSFO), and Ba0.5Pb0.5Fe12O19 (BPFO) were synthesized by commercial solid state reaction method. The Rietveld refinement of x-ray powder diffraction revealed a single hexagonal phase with space group P63/mmc for BFO, SFO, and BSFO samples, whereas BPFO sample contains hematite (α-Fe2O3) phase with space group R3c along with the M-type main phase. All the samples show dispersion in dielectric constant (ɛ') and dielectric loss (tan δ) values with frequency. The values of ɛ' and tan δ increase with increase in temperature due to increase in the number of charge carriers and their mobilities, which are thermally activated. The reciprocal temperature dependence of conductivity (σac) and the most probable relaxation time (τM″) satisfies the Arrhenius relation. A perfect overlapping of the normalized plots of modulus isotherms on a single "super curve" for all the studied temperatures reveals a temperature independence of dynamic processes involved in conduction and for relaxation. Further, the complex plots of M* (M″ vs M') indicate that dc conductivity dominates in the region below the M″max point. Above M″max, the variations follow Jonscher power law (σ = Aωs) implying that ac conductivity is dominating in this region. Among the prepared samples, SFO hexaferrite has lowest values of σac, ɛ', and tan δ making it suitable for use in microwave devices.

  6. Solubility of BaS in BaO-BaF2 slag and the Influence of FeOx, SiO2, Cr2O3, BaCI2, CaO, and MgO on the sulfide capacity of this system

    NASA Astrophysics Data System (ADS)

    Rachev, Ivan P.; Tsukihashi, Fumitaka; Sano, Nobuo

    1992-03-01

    The influence of SiO2, FeOx, Cr2O3, BaCl2, CaO, and MgO on the sulfide capacity of the BaO-BaF2 system was measured at 1473 K, using a gas-slag-metal equilibration technique. It was found that the substitution of BaF2 by SiO2, FeOx, Cr2O3, and BaCl2 decreases the sulfide capacity of the BaO-BaF2 system. Similar results were obtained for the carbonate capacity. The CaO-saturated BaO-BaF2 flux, however, was found to have slightly higher sulfide and carbonate capacities than the pure BaO-BaF2 flux. The solubility of CaO increased with increasing BaF2 content and was 18 mol pet in BaF2 at 1473 K. The solubility of MgO in the BaO-BaF2 system at the same temperature is very low, and it has no effect on the sulfide and carbonate capacities. The solubility of BaS in the BaO-BaF2 system was also measured at 1473 K and had its maximum for the slag containing 40 mass pet BaO. The activity of BaO in the system was calculated from those data.

  7. Geoenvironmental weathering/deterioration of landfilled MSWI-BA glass.

    PubMed

    Wei, Yunmei; Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki; Zhao, Chun; Peng, Xuya; Gao, Junmin

    2014-08-15

    Municipal solid waste incineration bottom ash (MSWI-BA) glass serves as a matrix of assorted bottom ash (BA) compounds. Deterioration of the BA glass phases is quite important as they regulate the distribution of a series of toxic elements. This paper studied landfilled MSWI-BA samples from the mineralogical and geochemical viewpoint to understand the deterioration behavior of the BA glass phases as well as mechanisms involved. Bulk analysis by PXRD as well as micro-scale analysis by optical microscopy and SEM/EDX was conducted for such purposes. The results revealed that dissolution of the BA glass phases has resulted in a deterioration layer of 10(0)-10(2)μm thickness after years of disposal. This rapid weathering process is highly relevant to the specific glass characteristics and solution pH. The BA glass phases with more embedded compounds and cracks/fissures tend to be more vulnerable. Moreover, the generally alkaline pH in ash deposit favors a rapid disruption of the glass phase. The weathering products are mainly gel phases (including Al-Si gel, Ca-Al-Si gel, Fe-Al-Si gel etc.) with iron oxide/hydroxide as accessory products. Breakdown of the BA glass phases triggers chemical evolution of the embedded compounds. Based on all the findings above, a model is proposed to illustrate a general evolution trend for the landfilled MSWI-BA glass phases.

  8. Growth and characterization of acentric BaHf(BO3)2 and BaZr(BO3)2

    NASA Astrophysics Data System (ADS)

    Mączka, Mirosław; Szymborska-Małek, Katarzyna; Gągor, Anna; Majchrowski, Andrzej

    2015-05-01

    Growth, single crystal X-ray diffraction, polarized Raman and infrared (IR) studies of BaHf(BO3)2 are presented. Raman and IR spectra of polycrystalline BaZr(BO3)2 are also reported to facilitate assignment of modes. BaHf(BO3)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 HfO6 octahedra and BaO6 distorted trigonal prisms that are connected through borate groups. The obtained structural as well as spectroscopic data show that BaHf(BO3)2 is isostructural with BaZr(BO3)2 and the deviations from centrosymmetry is small.

  9. Electronic and optical properties of BaTe, BaSe and BaS from first principles

    NASA Astrophysics Data System (ADS)

    Pourghazi, A.; Dadsetani, M.

    2005-12-01

    Electronic and optical properties of barium chalcogenide compounds BaX (X=S, Se and Te) in NaCl crystal structure are calculated using the band structure results obtained through the full potential linearized augmented plane wave (FP-LAPW) method. The exchange correlation potential is treated by the generalized gradient approximation. The real and imaginary parts of the dielectric function ε(ω), the optical absorption coefficient I(ω), the reflectivity R(ω) and the energy loss function are calculated. The calculated results show good agreement with the available experimental results, particularly in the low-energy region of the spectra. Furthermore the interband transitions responsible for the structures seen in the spectra are specified. It is shown that the chalcogen p states and Ba 5d states play a major role in optical transitions as initial and final states, respectively. The effect of the spin-orbit coupling on the optical properties is also investigated and found to be significant, especially in high-energy regions.

  10. Hadron Physics at BaBar

    SciTech Connect

    Muller, David; /SLAC

    2005-10-26

    The BaBar experiment at SLAC is designed to measure CP violation in the B meson system, however the very high statistics combined with the different e{sup +} and e{sup -} beam energies, the detector design and the open trigger allow a wide variety of spectroscopic measurements. We are beginning to tap this potential via several production mechanisms. Here we present recent results from initial state radiation, hadronic jets, few body B and D hadron decays, and interactions in the detector material. We also summarize measurements relevant to D{sub s} meson spectroscopy, pentaquarks and charmonium spectroscopy from multiple production mechanisms.

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

    PubMed

    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.

  12. Thermoelectric properties of (BaCoO3-y)n BaCo8O11

    NASA Astrophysics Data System (ADS)

    Funahashi, Ryoji; Barbier, Tristan

    2016-08-01

    Thermoelectric properties of a homologous oxide system of (BaCoO3-y)nBaCo8O11 have been investigated at 373-973 K in air. All samples show positive Seebeck coefficient values, S, namely p-type character. Electrical resistivity, ρ of BaCoO3-y (n = ∞) decreases monotonically with increasing temperature. On the other hand, a transition in the electrical conduction is observed in the BaCo8O11 (n = 0), Ba2Co9O14 (n = 1), and Ba3Co10O17 (n = 2) around 500 K. Thermal conductivity looks to be decreased by the corner shared CoO6 structure. As the result of these properties, values of dimension-less figure of merit, ZT increase with increasing temperature and reach about 0.03 at 973 K for Ba2Co9O14. Cationic substitution at the Ba site has been carried out. The composition is Ba1.9M0.1Co9O14 (M: Na, Ca, Sr, and La). The substitution by Na is the most effective to enhance the S values at temperatures lower than 573 K. The values of power factor (= S2/ρ) for the samples substituted by Na and Sr are reach 0.1 mW/m.K2 at 773 K.

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

    NASA Astrophysics Data System (ADS)

    Rogge, J.; Hetaba, W.; Schmalhorst, J.; Bouchikhaoui, H.; Stender, P.; Baither, D.; Schmitz, G.; Hütten, A.

    2015-07-01

    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.

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

    ERIC Educational Resources Information Center

    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…

  15. Unitarity Triangle Angle Measurements at BaBar

    SciTech Connect

    Latham, Thomas E.; /SLAC

    2005-06-30

    We present recent results of measurements of the Unitarity Triangle angles alpha, beta and gamma made with the BaBar detector at the PEP-II asymmetric B factory. We present recent results of measurements of the Unitarity Triangle angles alpha, beta and gamma made with the BaBar detector at the PEP-II asymmetric B factory.

  16. Superstructure formation in SrBa8[BN2]6 and EuBa8[BN2]6.

    PubMed

    Seidel, Stefan; Dierkes, Tobias; Jüstel, Thomas; Benndorf, Christopher; Eckert, Hellmut; Pöttgen, Rainer

    2016-07-26

    X-ray pure samples of SrBa8[BN2]6 and EuBa8[BN2]6 were synthesized from appropriate amounts of binary nitrides (Sr3N2, Ba3N2 and BN in sealed niobium ampoules and EuN, Ba3N2 and BN in BN crucibles, respectively) at temperatures up to 1370 K. The structure of SrBa8[BN2]6 was refined from single crystal X-ray diffractometer data: Fd3[combining macron]m, a = 1595.1(1) pm, wR(F(2)) = 0.0515, 387 F(2) values and 21 variables. EuBa8[BN2]6 has a lattice parameter of 1595.00(9) pm. Both nitridoborates adopt a new 2 × 2 × 2 superstructure variant of the LiCa4[BN2]3 type, realized through ordering of vacancies and Sr(2+) and Eu(2+) cations, respectively. The structures of SrBa8[BN2]6 and LiCa4[BN2]3 are related by a group-subgroup scheme. The Sr(2+)/vacancy ordering leads to an asymmetric coordination (1 × Sr(2+) and 8 × Ba(2+) in a distorted, mono-capped square prism) for the [BN2](3-) units with B-N distances of 132 and 136 pm. Vibrational spectra of SrBa8[BN2]6 and EuBa8[BN2]6 confirm the discrete linear [BN2](3-) units and (11)B solid state MAS NMR spectra are compatible with single crystallographic sites for the boron atoms. In EuBa8[BN2]6 the spectra are profoundly influenced by interactions of the (11)B nuclei with the unpaired electrons of the paramagnetic Eu(2+) ions. PMID:27397545

  17. Superstructure formation in SrBa8[BN2]6 and EuBa8[BN2]6.

    PubMed

    Seidel, Stefan; Dierkes, Tobias; Jüstel, Thomas; Benndorf, Christopher; Eckert, Hellmut; Pöttgen, Rainer

    2016-07-26

    X-ray pure samples of SrBa8[BN2]6 and EuBa8[BN2]6 were synthesized from appropriate amounts of binary nitrides (Sr3N2, Ba3N2 and BN in sealed niobium ampoules and EuN, Ba3N2 and BN in BN crucibles, respectively) at temperatures up to 1370 K. The structure of SrBa8[BN2]6 was refined from single crystal X-ray diffractometer data: Fd3[combining macron]m, a = 1595.1(1) pm, wR(F(2)) = 0.0515, 387 F(2) values and 21 variables. EuBa8[BN2]6 has a lattice parameter of 1595.00(9) pm. Both nitridoborates adopt a new 2 × 2 × 2 superstructure variant of the LiCa4[BN2]3 type, realized through ordering of vacancies and Sr(2+) and Eu(2+) cations, respectively. The structures of SrBa8[BN2]6 and LiCa4[BN2]3 are related by a group-subgroup scheme. The Sr(2+)/vacancy ordering leads to an asymmetric coordination (1 × Sr(2+) and 8 × Ba(2+) in a distorted, mono-capped square prism) for the [BN2](3-) units with B-N distances of 132 and 136 pm. Vibrational spectra of SrBa8[BN2]6 and EuBa8[BN2]6 confirm the discrete linear [BN2](3-) units and (11)B solid state MAS NMR spectra are compatible with single crystallographic sites for the boron atoms. In EuBa8[BN2]6 the spectra are profoundly influenced by interactions of the (11)B nuclei with the unpaired electrons of the paramagnetic Eu(2+) ions.

  18. First-principles study of electronic and optical properties of BaS, BaSe and BaTe

    NASA Astrophysics Data System (ADS)

    Feng, Zhenbao; Hu, Haiquan; Lv, Zengtao; Cui, Shouxin

    2010-10-01

    The optimized crystal structure, energy band structures, density of states (DOS) and optical properties of BaX (X=S, Se and Te) were investigated by the full potential linearized augmented plane wave plus local orbitals method (FP-LAPW+lo). The exchange-correlation potential was treated using the generalized gradient approximation (GGA). We have used also Engel and Vosko GGA (EV-GGA) formalism to improve the band gap results. The calculated results such as band gaps, dielectric constants and reflectivity spectra showed good agreement with the experimental data. The effect of the spin-orbit coupling (SOC) on the optical properties was also studied and found to be very small, especially in the low-energy region.

  19. Surface segregation of Ba in MgO

    NASA Astrophysics Data System (ADS)

    Cotter, M.; Campbell, S.; Cao, L. L.; Egdell, R. G.; Mackrodt, W. C.

    1989-02-01

    Surface segregation of Ba in doped polycrystalline and single crystal MgO has been studied by XPS. There is little variation in surface coverage of Ba over a range of bulk doping levels from 7 to 7000 ppm in ceramic pellets equilibrated at 1630 K. This remarkable behaviour is shown to be consistent with surface coverage calculated from heats of segregation derived from ionic model simulations of the surface if due account is taken of the strong variation of the segregation energy with coverage. The coverage of Ba on a MgO(001) single crystal surface doped by indiffusion of Ba deposited onto the crystal from a getter source can be made similar to that of the polycrystalline material. The Ba-segregated MgO(001) surface exhibits a complex LEED pattern.

  20. Superconductivity in Ba(Pb,Bi,Sb)O 3, Ba(Pb,Bi,Te)O 3 and (Ba,La) (Pb,Bi,Tl)O 3 systems

    NASA Astrophysics Data System (ADS)

    Nagarajan, R.; Vasanthacharya, N. Y.; Gopalakrishnan, J.; Rao, C. N. R.

    1991-02-01

    It is possible to substitute Bi in the superconducting BaPb 0.75Bi 0.25O 3 by Sb or Te without destroying the superconductivity. With Sb, a continuous series of solid solutions BaPb 0.75Bi 0.25-ySb yO 3 (0 ⩽ y ⩽ 0.25) exists, while with Te, perovskite BaPb 0.75Bi 0.25-yTe yO 3 exists only upto y = 0.15. With increasing substitution by Sb or Te, T c decreases continously in both the systems. Superconductivity with a maximum T c of 8K is found in Ba 0.9La 0.1Pb 0.9-yBi yTl 0.1O 3 for y = 0.25.

  1. Innovative methodology for the synthesis of Ba-M hexaferrite BaFe{sub 12}O{sub 19} nanoparticles

    SciTech Connect

    Ahmed, M.A.; Helmy, N.; El-Dek, S.I.

    2013-09-01

    Graphical abstract: Transmission electron microscope images for the BaFe12O19. - Highlights: • BaFe{sub 12}O{sub 19}nanoparticles were prepared in single-phase from organometallic precursors. • BaFe{sub 12}O{sub 19} possesses small size 65 nm, H{sub C} = 3695 Oe and M{sub s} = 58 emu/g. • This method of preparation could be extended in the synthesis of other metal oxide nanoparticles. - Abstract: In this piece of work, high quality and homogeneity, barium hexaferrite (BaM) BaFe{sub 12}O{sub 19} nanoparticles were prepared from organometallic precursors for the 1st time. This method is based on the formation of supramolecular crystal structure of Ba[Fe(H{sub 3}NCH{sub 2}CH{sub 2}NH{sub 3})]Cl{sub 7}·8H{sub 2}O. The crystal structure, morphology and magnetic properties of BaFe{sub 12}O{sub 19} at two different annealing temperatures namely 1000 °C and 1200 °C were investigated using X-ray diffraction, transmission electron microscope TEM and vibrating sample magnetometry (VSM). The results show that monophasic nanoparticles of hexaferrites were obtained. Nanoparticles of crystallite size 40–50 nm distinguished by narrow distribution and excellent homogeneity were obtained with superior magnetic properties which suggested single-domain particles of Ba-M hexaferrite.

  2. G factor of the 2/sub 1//sup +/ state in /sup 140/Ba and /sup 142/Ba

    SciTech Connect

    Pauling, L.

    1987-06-01

    A simple calculation on the basis of the revolving cluster model leads to the value 0.495 for the g factor of /sub //sub <1/ /sub 56//sup 42/Ba/sub 86/, in agreement with the experimental value 0.48 +- 0.14. The same value is predicted for /sup 140/Ba.

  3. Crystal Structure and Thermodynamic Stability of Ba/Ti-Substituted Pollucites for Radioactive Cs/Ba Immobilization

    SciTech Connect

    Xu, Hongwu; Chavez, Manuel E.; Mitchell, Jeremy N.; Garino, Terry J.; Schwarz, Haiqing L.; Rodriguez, Mark A.; Rademacher, David X.; Nenoff, Tina Maria

    2015-04-23

    An analogue of the mineral pollucite (CsAlSi2O6), CsTiSi2O6.5 has a potential host phase for radioactive Cs. However, as 137Cs and 135Cs transmute to 137Ba and 135Ba, respectively, through the beta decay, it is essential to study the structure and stability of this phase upon Cs → Ba substitution. In this work, two series of Ba/Ti-substituted samples, CsxBa(1-x)/2TiSi2O6.5 and CsxBa1-xTiSi2O7-0.5x, (x = 0.9 and 0.7), were synthesized by high-temperature crystallization from their respective precursors. Synchrotron X-ray diffraction and Rietveld analysis reveal that while CsxBa(1-x)/2TiSi2O6.5 samples are phase-pure, CsxBa1-xTiSi2O7-0.5x samples contain Cs3x/(2+x)Ba(1-x)/(2+x)TiSi2O6.5 pollucites (i.e., also two-Cs-to-one-Ba substitution) and a secondary phase, fresnoite (Ba2TiSi2O8). Thus, the CsxBa1-xTiSi2O7-0.5x series is energetically less favorable than CsxBa(1-x)/2TiSi2O6.5. To study the stability systematics of CsxBa(1-x)/2TiSi2O6.5 pollucites, high-temperature calorimetric experiments were performed at 973 K with or without the lead borate solvent. Enthalpies of formation from the constituent oxides (and elements) have thus been derived. Our results show that with increasing Ba/(Cs + Ba) ratio, the thermodynamic stability of these phases decreases with respect to their component oxides. Hence, from the energetic viewpoint, continued Cs → Ba transmutation tends to destabilize the parent silicotitanate pollucite structure. However, the Ba-substituted pollucite co-forms with fresnoite (which incorporates the excess Ba

  4. Electronic structure of BaO/W cathode surfaces

    NASA Technical Reports Server (NTRS)

    Muller, Wolfgang

    1989-01-01

    The local electronic structure of the emissive layer of barium dispenser thermionic cathodes is investigated theoretically using the relativistic scattered-wave approach. The interaction of Ba and O with W, Os, and W-Os alloy surfaces is studied with atomic clusters modeling different absorption environments representative of B- and M-type cathodes. Ba is found to be strongly oxidized, while O and the metal substrate are in a reduced chemical state. The presence of O enhances the surface dipole and Ba binding energy relative to Ba on W. Model results for W-Os alloy substrates show only relatively small changes in Ba and O for identical geometries, but very large charge redistributions inside the substrate, which are attributed to the electronegativity difference between Os and W. If Os is present in the surface layer, the charge transfer from Ba to the substrate and the Ba binding energy increase relative to W. Explanations are offered for the improved electron emission from alloy surfaces and the different emission enhancement for different alloy substrates.

  5. Ba2TeO: A new layered oxytelluride

    DOE PAGES

    Besara, T.; Ramirez, D.; Sun, J.; Whalen, J. B.; Tokumoto, T. D.; McGill, S. A.; Singh, D. J.; Siegrist, T.

    2015-02-01

    For single crystals of the new semiconducting oxytelluride phase, Ba2TeO, we synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba2TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. Moreover, the optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba2TeO is highly insulating.

  6. AMiBA: Array for Microwave Background Anisotropy

    NASA Astrophysics Data System (ADS)

    Umetsu, Keiichi

    2003-07-01

    AMiBA (Array for Microwave Background Anisotropy) is a dual-channel 85-105 GHz interferometric array with full polarization capabilities sited on Mauna-Loa in Hawaii, being built by collaboration between ASIAA/NTU in Taiwan and the Australia Telescope Facility. AMiBA is specifically designed to probe the polarization properties of the Cosmic Microwave Background (CMB) as well as to search for high redshift galaxy clusters via Sunyaev-Zel'dovich effect. Here we review the basic concepts and design details of AMiBA, and explore its potential especially for measuring the CMB temperature and polarization power spectra.

  7. X-ray Rietveld refinement of structure of Ba-deficient Ba3Si6O12N2:Eu phosphor

    NASA Astrophysics Data System (ADS)

    Moriga, Toshihiro; Fujigaki, Hiroshi; Ogita, Yuma; Muguruma, Issei; Bando, Fumika; Murai, Kei-Ichiro; Waterhouse, Geoffrey I. N.

    2015-03-01

    Green oxynitride phosphors Ba3Si6O12N2 were prepared with metallic ratio of Si/Ba = 3. It was found that the nonstoichiometric mixture at Si/Ba = 3 formed the Ba3Si6O12N2-type phase easier than the stoichiometric one at Si/Ba = 2 after it was fired at 1200°C for 5 h under a diluted hydrogen flow (5%H2-95%N2). The excess Si source led to a formation of SiO2 glass, which can act as a flux in case of formation of Ba3Si6O12N2.

  8. Transition probabilities in the X(5) candidate {sup 122}Ba

    SciTech Connect

    Bizzeti, P. G.; Giannatiempo, A.; Melon, B.; Perego, A.; Sona, P.; Bizzeti-Sona, A. M.; Tonev, D.; Ur, C. A.; Bazzacco, D.; Farnea, E.; Marginean, R.; Menegazzo, R.; Rossi Alvarez, C.; Dewald, A.; Fransen, C.; Michelagnoli, C.; Lenzi, S.; Lunardi, S.; Mengoni, D.; Nespolo, M.

    2010-11-15

    To investigate the possible X(5) character of {sup 122}Ba, suggested by the ground-state band energy pattern, the lifetimes of the lowest yrast states of {sup 122}Ba have been measured, via the recoil distance Doppler-shift method. The relevant levels have been populated by using the {sup 108}Cd({sup 16}O,2n){sup 122}Ba and the {sup 112}Sn({sup 13}C,3n){sup 122}Ba reactions. The B(E2) values deduced in the present work are compared to the predictions of the X(5) model and to calculations performed in the framework of the IBA-1 and IBA-2 models.

  9. A Novel BA Complex Network Model on Color Template Matching

    PubMed Central

    Han, Risheng; Yue, Guangxue; Ding, Hui

    2014-01-01

    A novel BA complex network model of color space is proposed based on two fundamental rules of BA scale-free network model: growth and preferential attachment. The scale-free characteristic of color space is discovered by analyzing evolving process of template's color distribution. And then the template's BA complex network model can be used to select important color pixels which have much larger effects than other color pixels in matching process. The proposed BA complex network model of color space can be easily integrated into many traditional template matching algorithms, such as SSD based matching and SAD based matching. Experiments show the performance of color template matching results can be improved based on the proposed algorithm. To the best of our knowledge, this is the first study about how to model the color space of images using a proper complex network model and apply the complex network model to template matching. PMID:25243235

  10. AMiBA: Array for Microwave Background Anisotropy

    NASA Astrophysics Data System (ADS)

    Lo, K.; Martin, R.; Chiueh, T.

    As part of a 4-year Cosmology and Particle Astrophysics (CosPA) Research Excellence Initiative in Taiwan, AMiBA $-$ a 19-element dual-channel 85-105 GHz interferometer array is being specifically built to search for high redshift clusters of galaxies via the Sunyaev-Zeldovich Effect (SZE). In addition, AMiBA will have full polarization capabilities, in order to probe the polarization properties of the Cosmic Microwave Background. AMiBA, to be sited on Mauna Kea in Hawaii or in Chile, will reach a sensitivity of $\\sim 1$ mJy or 7$\\mu$K in 1 hour. The project involves extensive international scientific and technical collaborations. The construction of AMiBA is scheduled to starting operating in early 2004.

  11. AMiBA: Array for microwave background anisotropy

    NASA Astrophysics Data System (ADS)

    Lo, K. Y.; Chiueh, T. H.; Martin, R. N.; Ng, Kin-Wang; Liang, H.; Pen, Ue-Li; Ma, Chung-Pei; Kesteven, M.; Sault, R.; Subrahmanyan, R.; Wilson, W.; Peterson, J.

    2001-10-01

    As part of a 4-year Cosmology and Particle Astrophysics (CosPA) Research Excellence Initiative in Taiwan, AMiBA-a 19-element dual-channel 85-105 GHz interferometer array is being specifically built to search for high redshift clusters of galaxies via the Sunyaev-Zeldovich Effect (SZE). In addition, AMiBA will have full polarization capabilities, in order to probe the polarization properties of the Cosmic Microwave Background. AMiBA, to be sited on Mauna Kea in Hawaii or in Chile, will reach a sensitivity of ~1 mJy or 9 μK in 1 hour. The project involves extensive international scientific and technical collaborations. The construction of AMiBA is scheduled to start operating in early 2004. .

  12. Evidence of fissiogenic Cs estimated from Ba isotopic deviations in an Oklo natural reactor zone

    NASA Astrophysics Data System (ADS)

    Hidaka, Hiroshi; Holliger, Philippe; Masuda, Akimasa

    1993-01-01

    Isotopic studies of many elements from the uranium ore natural nuclear reactors at Oklo provide useful information on the migration of radioactive nuclides. The fissiogenic isotopic composition of Ba is particularly interesting, as it is an important indication in the search for fissiogenic Cs. In this report we detail the detection of remarkable isotopic deviations of Ba in the Oklo samples and estimate the geochemical behaviour of fissiogenic Cs from excess Ba isotopes. Six samples systematically collected from borehole SF84 (zone 10) at the Oklo uranium mine have been analyzed. Isotopic deviations of Ba indicate the existence of fissiogenic Cs and Ba. A good correlation between the elemental abundance of Cs and isotopic abundances of excess 135Ba and 137Ba suggests that fissiogenic 135Ba and 137Ba behaved as Cs rather than Ba.

  13. Formation of single-phase BaO nanoclusters

    SciTech Connect

    Du, Yingge; Kim, Dong Jun; Varga, Tamas; Wang, Zhitao; Szanyi, Janos; Lyubinetsky, Igor

    2011-06-01

    Combined analysis employing in-situ X-rays photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and ex-situ X-ray diffraction (XRD) has demonstrated the feasibility to deposit single-phase barium oxide overlayers by a direct sublimation of BaO material from an effusion cell. Furthermore, in situ scanning tunneling microscopy (STM) has confirmed that the BaO grows as nanoclusters with dimensions down to ~2 nm.

  14. Leptonic B Decays at BaBar

    SciTech Connect

    Baracchini, Elisabetta; /Rome U. /INFN, Rome

    2011-11-10

    We will present the most recent results on leptonic B decays B{sup {+-}(0)} {yields} K*{sup {+-}(0)}{nu}{bar {nu}} and B{sup {+-}} {yields} {mu}{sup {+-}}{nu}, based on the data collected by the BaBar detector at PEP-II, an asymmetric e{sup +}e{sup -} collider at the center of mass energy of the {Upsilon}(4S) resonance. Rare B decays have always been a standard probe for New Physics (NP) searches. The very low Standard Model (SM) rate of these decays often make them unaccessible with the present experimental datasets, unless NP effects enhance the rate up to the current experimental sensitivity. Moreover, as NP effects can modify the decay kinematic, particular attention must be paid in order to perform a model independent analysis. A B-Factory provides an unique environment to investigate these processes. The high number of B{bar B} pairs produced by a B-Factory often allows to approach the needed experimental sensitivity. Moreover, the clean environment and the closed kinematic of the initial state enable to obtaining a very pure sample where to look for these decays.

  15. Tests of AMiBA Data Integrity

    NASA Astrophysics Data System (ADS)

    Nishioka, Hiroaki; Wang, Fu-Cheng; Wu, Jiun-Huei Proty; Ho, Paul T. P.; Huang, Chih-Wei Locutus; Koch, Patrick M.; Liao, Yu-Wei; Lin, Kai-Yang; Liu, Guo-Chin; Molnar, Sandor M.; Umetsu, Keiichi; Birkinshaw, Mark; Altamirano, Pablo; Chang, Chia-Hao; Chang, Shu-Hao; Chang, Su-Wei; Chen, Ming-Tang; Han, Chih-Chiang; Huang, Yau-De; Hwang, Yuh-Jing; Jiang, Homin; Kesteven, Michael; Kubo, Derek Y.; Li, Chao-Te; Martin-Cocher, Pierre; Oshiro, Peter; Raffin, Philippe; Wei, Tashun; Wilson, Warwick

    2009-04-01

    We describe methods used to validate data from the Y.T. Lee Array for Microwave Background Anisotropy (AMiBA), an interferometric array designed to measure the Sunyaev-Zel'dovich effect and the anisotropy of the cosmic microwave background. We perform several statistical tests on data from pointed observations of galaxy clusters taken in 2007 and noise data from long-term blank-sky observations and measurements with the feeds covered by the absorbers. We apply power-spectrum analysis, cross-power-spectrum analysis among different outputs with different time lags in our analog correlator, and sample-variance law tests to noise data. We find that (1) there is no time variation of electronic offsets on the timescale of our two-patch observations (~10 minutes); (2) noise is correlated by less than 10% between different lags; and (3) the variance of noise scales with the inverse of time. To test the Gaussianity of the data, we apply Kolmogorov-Smirnov tests to cluster data and find that a 5% significance level efficiently detects data sets with known hardware problems without rejecting an excess of acceptable data. We also calculate third- and fourth-order moments and cumulants for the noise residual visibilities and find that about 95% of our data are within the 99% confidence regions of Gaussianity.

  16. The metallic Zintl phase Ba 3Sn 4As 6

    NASA Astrophysics Data System (ADS)

    Lam, Robert; Mar, Arthur

    2001-05-01

    The ternary Zintl compound barium tin arsenide, Ba 3Sn 4As 6, has been synthesized at 950 °C, and its structure has been determined by single-crystal X-ray diffraction methods. It crystallizes in the monoclinic space group C2 h5- P2 1/ n with a=8.6374(10) Å, b=18.3536(13) Å, c=9.7209(11) Å, β=90.05(2)°, and Z=4 at 22 °C. The structure of Ba 3Sn 4As 6 can be regarded as an intermediate between the hypothetical limiting structures "Ba 4Sn 2As 6", containing one-dimensional corner-sharing chains of Sn-centered tetrahedra and "Ba 2Sn 6As 6", containing two-dimensional corrugated layers with pentagonal channels. The Ba 2+ cations separate these chains or layers. Resistivity measurements indicate weakly metallic behaviour for Ba 3Sn 4As 6 with a room-temperature resistivity of 2.7×10 -4Ω cm.

  17. Ba termination of Ge(001) studied with STM

    NASA Astrophysics Data System (ADS)

    Curson, Neil; Koczorowski, Wojciech; Grzela, Tomasz; Radny, Marian; Schofield, Steven; Capellini, Giovanni; Czajka, Ryszard; Schroeder, Thomas

    2015-03-01

    We use controlled annealing to tune the interfacial properties of a sub-monolayer and monolayer coverages of Ba atoms deposited on Ge(001), enabling the generation of either of two fundamentally distinct interfacial phases, as revealed by scanning tunneling microscopy (STM). Firstly we identify the two key structural phases associated with this adsorption system, namely on-top adsorption and surface alloy formation, by performing a deposition and annealing experiment at a coverage low enough (0.15 ML) such that isolated Ba-related features can be individually resolved. Subsequently we investigate the monolayer coverage case, of interest for passivation schemes of future Ge based devices, for which we find that thermal evaporation of Ba onto a Ge(001) surface at room temperature results in on-top adsorption. This separation (lack of intermixing) between Ba and Ge layers is retained through successive annealing steps up to 770 K with a gradual ordering of the Ba layer at 570 K and above and a decrease in Ba layer density. Annealing above 770 K produces the 2-D surface alloy phase accompanied by strain relief through monolayer height trench formation. At 1070 K the surface morphology changes again but remains a 2-D surface alloy. WK and NJC acknowledge EPSRC grant EP/I02865X/1. WK, MWR and R.C. acknowledge the Polish Ministry of Science and Higher Education for support (Project No. N-N202-195840).

  18. Constraining Intracluster Gas Models with AMiBA13

    NASA Astrophysics Data System (ADS)

    Molnar, Sandor M.; Umetsu, Keiichi; Birkinshaw, Mark; Bryan, Greg; Haiman, Zoltán; Hearn, Nathan; Shang, Cien; Ho, Paul T. P.; Locutus Huang, Chih-Wei; Koch, Patrick M.; Liao, Yu-Wei Victor; Lin, Kai-Yang; Liu, Guo-Chin; Nishioka, Hiroaki; Wang, Fu-Cheng; Proty Wu, Jiun-Huei

    2010-11-01

    Clusters of galaxies have been extensively used to determine cosmological parameters. A major difficulty in making the best use of Sunyaev-Zel'dovich (SZ) and X-ray observations of clusters for cosmology is that using X-ray observations it is difficult to measure the temperature distribution and therefore determine the density distribution in individual clusters of galaxies out to the virial radius. Observations with the new generation of SZ instruments are a promising alternative approach. We use clusters of galaxies drawn from high-resolution adaptive mesh refinement cosmological simulations to study how well we should be able to constrain the large-scale distribution of the intracluster gas (ICG) in individual massive relaxed clusters using AMiBA in its configuration with 13 1.2 m diameter dishes (AMiBA13) along with X-ray observations. We show that non-isothermal β models provide a good description of the ICG in our simulated relaxed clusters. We use simulated X-ray observations to estimate the quality of constraints on the distribution of gas density, and simulated SZ visibilities (AMiBA13 observations) for constraints on the large-scale temperature distribution of the ICG. We find that AMiBA13 visibilities should constrain the scale radius of the temperature distribution to about 50% accuracy. We conclude that the upgraded AMiBA, AMiBA13, should be a powerful instrument to constrain the large-scale distribution of the ICG.

  19. Electronic structure, optical properties and bonding in alkaline earth halo-fluoride scintillators: BaClF, BaBrF and BaIF

    SciTech Connect

    Yedukondalu, N.; Babu, K. Ramesh; Bheemalingam, Ch.; Singh, David J; Vaitheeswaran, G.; Kanchana, V.

    2011-01-01

    We report first-principles studies of the structural, electronic, and optical properties of the alkaline-earth halofluorides, BaXF (X = Cl, Br, and I), including pressure dependence of structural properties. The band structures show clear separation of the halogen p derived valence bands into higher binding energy F and lower binding energy X derived manifolds reflecting the very high electronegativity of F relative to the other halogens. Implications of this for bonding and other properties are discussed. We find an anisotropic behavior of the structural parameters especially of BaIF under pressure. The optical properties on the other hand are almost isotropic, in spite of the anisotropic crystal structures.

  20. Effects of Hexagonal BaTiO3 Addition on Textured BaTiO3 Thick Films Prepared by Screen Printing

    NASA Astrophysics Data System (ADS)

    Sakai, Yuichi; Futakuchi, Tomoaki

    2013-09-01

    The effects of hexagonal BaTiO3 addition to BaTiO3 thick films were examined. A- and c-axis-preferred BaTiO3 thick films were prepared by hexagonal BaTiO3 addition. The addition of the hexagonal Ba(Ti0.96Mn0.04)O3 was more effective for preparing the a- and c-axis-preferred thick films than the addition of the hexagonal BaTiO3 prepared by reducing BaTiO3 in a 3% H2-N2 atmosphere. According to increases in the firing time at 1370 °C, the Mn of Ba(Ti0.96Mn0.04)O3 in the Ba(Ti0.96Mn0.04)O3-added BaTiO3 thick films was diffused, and the hexagonal phase in the thick films changed to the tetragonal phase. The degree of the preferred orientation of the Ba(Ti0.96Mn0.04)O3-added BaTiO3 thick films increased with increasing firing time. The hexagonal-phase ratio of the reduced BaTiO3-added BaTiO3 thick films decreased markedly when the firing temperature was above 1000 °C. The existence of the hexagonal phase at 1370 °C in which the grain growth advanced could be important in obtaining highly oriented thick films. The tan δ values of the Ba(Ti0.96Mn0.04)O3-added BaTiO3 thick films were lower than 3%. The remanent polarizations of the thick films were greater than 7 µC/cm2.

  1. Structural properties of ultrafine Ba-hexaferrite nanoparticles

    SciTech Connect

    Makovec, Darko; Primc, Darinka; Sturm, Saso; Kodre, Alojz; Hanzel, Darko; Drofenik, Miha

    2012-12-15

    Crystal structure of ultrafine Ba-hexaferrite (BaFe{sub 12}O{sub 19}) nanoparticles was studied using X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption fine structure (XAFS), and Moessbauer spectroscopy (MS), to be compared to the structure of larger nanoparticles and the bulk. The nanoparticles were synthesized with hydrothermal treatment of an appropriate suspension of Ba and Fe hydroxides in the presence of a large excess of OH{sup -}. The ultrafine nanoparticles were formed in a discoid shape, {approx}10 nm wide and only {approx}3 nm thick, comparable to the size of the hexagonal unit cell in the c-direction. The HRTEM image analysis confirmed the hexaferrite structure, whereas EDXS showed the composition matching the BaFe{sub 12}O{sub 19} formula. XAFS and MS analyses showed considerable disorder of the structure, most probably responsible for the low magnetization. - Graphical abstract: Left: HREM image of an ultrafine Ba-hexaferrite nanoparticle (inset: TEM image of the nanoparticles); Right: the experimental HRTEM image is compared with calculated image and corresponding atomic model. Highlights: Black-Right-Pointing-Pointer Crystal structure of ultrafine Ba-hexaferrite (BaFe{sub 12}O{sub 19}) nanoparticles was compared to the structure of the bulk. Black-Right-Pointing-Pointer Thickness the discoid nanoparticles was comparable to the size of the hexagonal unit cell in the c-direction. Black-Right-Pointing-Pointer Considerable disorder of the nanoparticles' structure is most probably responsible for their low magnetization.

  2. Reactions of NO2 with BaO/Pt(111) Model Catalysts: The Effects of BaO Film Thickness and NO2 Pressure on the Formation of Ba(NOx)2 Species

    SciTech Connect

    Mudiyanselage, Kumudu; Yi, Cheol-Woo; Szanyi, Janos

    2011-05-31

    The adsorption and reaction of NO2 on BaO (<1, ~3, and >20 monolayer equivalent (MLE))/Pt(111) model systems were studied with temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and infrared reflection absorption spectroscopy (IRAS) under ultra-high vacuum (UHV) as well as elevated pressure conditions. NO2 reacts with sub-monolayer BaO (<1 MLE) to form nitrites only, whereas the reaction of NO2 with BaO (~3 MLE)/Pt(111) produces mainly nitrites and a small amount of nitrates under UHV conditions (PNO2 ~ 1.0 × 10-9 Torr) at 300 K. In contrast, a thick BaO(>20 MLE) layer on Pt(111) reacts with NO2 to form nitrite-nitrate ion pairs under the same conditions. At elevated NO2 pressures (≥ 1.0 × 10-5 Torr), however, BaO layers at all these three coverages convert to amorphous barium nitrates at 300 K. Upon annealing to 500 K, these amorphous barium nitrate layers transform into crystalline phases. The thermal decomposition of the thus-formed Ba(NOx)2 species is also influenced by the coverage of BaO on the Pt(111) substrate: at low BaO coverages, these species decompose at significantly lower temperatures in comparison with those formed on thick BaO films due to the presence of Ba(NOx)2/Pt interface where the decomposition can proceed at lower temperatures. However, the thermal decomposition of the thick Ba(NO3)2 films follows that of bulk nitrates. Results obtained from these BaO/Pt(111) model systems under UHV and elevated pressure conditions clearly demonstrate that both the BaO film thickness and the applied NO2 pressure are critical in the Ba(NOx)2 formation and subsequent thermal decomposition processes.

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

    PubMed

    Ardila, Alfredo; Bernal, Byron; Rosselli, Monica

    2016-01-01

    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"). PMID:27006905

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

    PubMed Central

    Bernal, Byron

    2016-01-01

    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”). PMID:27006905

  5. Thermodynamics and existing phase of Ba-phenanthrene

    NASA Astrophysics Data System (ADS)

    Heguri, Satoshi; Thi Nhu Phan, Quynh; Tanabe, Yoichi; Tanigaki, Katsumi

    2015-03-01

    The recent discovery of superconductivity in potassium doped picene suggested the possibility of a new class of superconductors. The problem is that no satisfactory guide to improve the superconducting shielding fraction had been provided until recently. However, a high superconducting shielding fraction of 65 % was reported for Ba1.5(phenanthrene). Considering this situation, phenanthrene (PHN) appears to be a key material for confirming the existence of metallicity and superconductivity in the aromatic hydrocarbon (AHC) family, and also for clarifying the physical properties and superconducting mechanism of AHC superconductors. In the present work, the thermodynamics for intercalation of PHN with Ba is studied in comparison with its isomer of anthracene (AN). Contrarily to previous reports by other authors, the important observation that Ba is intercalated into neither PHN nor AN without affecting their molecular structures is unambiguously made by differential scanning calorimetry measurements and annealing time dependences observed by powder x-ray diffraction measurements. The reactions of Ba and PHN at elevated temperatures lead this system to molecular decomposition instead of intercalation. The phenomena of metallicity and superconductivity in PHN intercalated with alkaline earth metals (Ba or Sr) should be reconsidered.

  6. Preparation of BaTiO3/Cu2O and BaTiO3/Cu2O/Au Complexes: Their Photocatalytic and Antipathogenic Effect.

    PubMed

    Cho, Sung-Woo; Nam, Dae-Hyun; Kim, Lee-Han; Jung, Dongwoon

    2016-05-01

    BaTiO3/Cu2O and BaTiO3/Cu2O/Au complexes were prepared from CuCl2, HAuCl4 solution, and BaTiO3 by the solution method. BaTiO3 particles were dispersed in a CuCl2 solution, and the BaTiO3/CuO complex was produced through crystallization of CuO onto the BaTiO3 surface by hydrolysis of CuCl2 in the first stage. After the reaction, CuO was reduced to Cu2O by treatment with glucose, thereby yielding the BaTiO3/Cu2O complex. The BaTiO3/Cu2O/Au complex was prepared by treating the BaTiO3/Cu2O particles with HAuCl4. Under visible light, the obtained BaTiO3/Cu2O0/Au complex showed higher photocatalytic activity than the Degussa P-25sample. In addition, the BaTiO3/Cu2O complex showed excellent antipathogenic effect. PMID:27483887

  7. Growth of BaTiO{sub 3} in hydrothermally derived (<100 C) BaTiO{sub 3}/polymer composite thin films

    SciTech Connect

    Collins, D.E.; Slamovich, E.B.

    1997-09-01

    Composite BaTiO{sub 3}/polymer films (< 1 {micro}m thickness) were processed by the in-situ growth of BaTiO{sub 3} particles in a polymer matrix. A solution of a polybutadiene-polystyrene triblock copolymer and titanium and diisoproxide bis(ethylacetoacetate) dissolved in toluene was cast onto an Ag-coated substrate. Subsequent hydrothermal treatment of the films in 1.0 M Ba(OH){sub 2} solutions at 80 C resulted in the nucleation and growth of BaTiO{sub 3} within the polymer matrix. The volume fraction/connectivity of BaTiO{sub 3} was controlled by varying the relative amounts of titanium precursor and polymer in solution. Growth of BaTiO{sub 3} within the polymer was examined by infrared spectroscopy and electron microscopy. The dielectric constant of the composite films increased with BaTiO{sub 3} content.

  8. Three new phosphates with isolated P2O7 units: noncentrosymmetric Cs2Ba3(P2O7)2 and centrosymmetric Cs2BaP2O7 and LiCsBaP2O7.

    PubMed

    Li, Lin; Han, Shujuan; Lei, Bing-Hua; Wang, Ying; Li, Hongyi; Yang, Zhihua; Pan, Shilie

    2016-03-01

    Three new phosphates, a noncentrosymmetric (NCS) Cs2Ba3(P2O7)2 and centrosymmetric (CS) Cs2BaP2O7 and LiCsBaP2O7, have been synthesized from high-temperature solutions for the first time. Analysis of the structures determined by single-crystal X-ray diffraction showed that although the three compounds contained isolated P2O7 units, they yielded different three-dimensional (3D) networks: Cs2Ba3(P2O7)2 crystallized in the NCS Orthorhombic space group P212121, Cs2BaP2O7 in the CS monoclinic space group P21/n, and LiCsBaP2O7, having an identical stoichiometry with Cs2BaP2O7, crystallized in monoclinic space group, P21/c. Structural comparisons suggested the differences between their 3D frameworks to be due to differences between the sizes and coordination environments of the cations. Characterizations including thermal and optical analyses showed Cs2Ba3(P2O7)2 and Cs2BaP2O7 to melt congruently, and Cs2Ba3(P2O7)2 to exhibit a wide transparent region with a cut-off edge below 176 nm. The NLO properties and electronic structures of these compounds were investigated using first-principles calcualtions. PMID:26831497

  9. Thermoelectric properties of Ni-doped BaSi2

    NASA Astrophysics Data System (ADS)

    Xu, Yidong; Wu, Yixuan; Chen, Zhiwei; Shen, Wenjia; Jian, Zhengzhong; Lin, Siqi; Li, Juan; Li, Wen; Pei, Yanzhong

    2016-01-01

    BaSi2 has been known as a wide gap semiconductor with an intrinsic low lattice thermal conductivity, therefore may be a promising environmental friendly thermoelectric (TE) material with abundant constituent elements. In this work, NixBa1-xSi2 compounds with 0≤x≤0.3 are synthesized by arc melting. The resistivity, thermal conductivity and Seebeck coefficient are measured in the temperature range of 300-850K. The resistivity of the undoped BaSi2 is as high as 480mOhmṡcm at room temperature. Through Ni-doping, both resistivity and the Seebeck coefficient decrease dramatically. Meanwhile, the total thermal conductivity has no apparent difference due to Ni-doping. The lattice thermal conductivity decreases with increasing temperature monotonously to be lower than 1W/mṡK at high temperatures.

  10. Antiferromagnetic Critical Fluctuations in BaFe$_2$As$_2$

    SciTech Connect

    Wilson, Stephen D; Yamani, Z.; Rotundu, C. R.; Freelon, B.; Valdivia, P. N.; Bourret-Courchesne, E. D.; Lynn, J W; Chi, Songxue; Hong, Tao; Birgeneau, R. J.

    2010-01-01

    Magnetic correlations near the magnetostructural phase transition in the bilayer iron-pnictide parent compound, BaFe{sub 2}As{sub 2}, are measured. In close proximity to the antiferromagnetic phase transition in BaFe{sub 2}As{sub 2}, a crossover to three-dimensional critical behavior is anticipated and has been preliminarily observed. Here we report complementary measurements of two-dimensional magnetic fluctuations over a broad temperature range about T{sub N}. The potential role of two-dimensional critical fluctuations in the magnetic phase behavior of BaFe{sub 2}As{sub 2} and their evolution near the anticipated crossover to three-dimensional critical behavior and long-range order are discussed.

  11. Chemical fabrication of superconducting Y-Ba-Cu oxide films

    NASA Astrophysics Data System (ADS)

    Hussain, A. A.; Sayer, M.

    1992-02-01

    High-Tc superconducting films of Y-Ba-Cu oxide were prepared on 100-plane MgO substrates by a sol-gel method. A procedure is described for preparing a superconducting film using acetate compounds dissolved in salicylic or lactic acids in the presence of ethylene glycol. This solution has superior qualities in terms of homogeneity, viscosity, and stability against atmospheric hydration. The results indicate that the nature of the solvent influences the microstructure and superconducting properties of Y-Ba-Cu-O films. X-ray diffraction analysis reveals that the annealed films are textured and had orthorhombic orientation. A correlation between the crystal structure and the superconducting properties of the Y-Ba-Cu-O films is presented.

  12. Raman sideband cooling of 138 Ba+ on a Zeeman transition

    NASA Astrophysics Data System (ADS)

    Seck, Christopher; Kokish, Mark; Dietrich, Matthew; Odom, Brian

    2016-05-01

    Here, we report motional ground state preparation of a single 138 Ba+ ion using Raman sideband cooling with the two S1/2 Zeeman sublevels. Owing to the small Zeeman splitting, Raman sideband cooling of 138 Ba+ requires only two AOMs and the Doppler cooling lasers. Additionally, we demonstrate coherent operations using a second, far-off-resonant laser driving Raman π-pulses between the two Zeeman sublevels to characterize our mean motional occupation number, Raman sideband cooling frequency resonance, Raman sideband cooling rate, and ion trap motional heating rate. Motional ground state cooling and molecular internal state preparation, both realized in our group, are important elements for molecular quantum logic spectroscopy (mQLS). We are now working towards motional ground state preparation of a 138 Ba+ and AlH+ ion pair for mQLS. Supported by the AFOSR and the NSF.

  13. Physical properties of single crystalline BaSn{sub 5}

    SciTech Connect

    Lin, Xiao; Budko, Sergey; Canfield, Paul

    2012-01-30

    We present a comprehensive study of the binary intermetallic superconductor, BaSn{sub 5}. High-quality single crystalline BaSn{sub 5} was grown out of a Sn flux. Detailed thermodynamic and transport measurements were performed to study BaSn{sub 5}'s normal and superconducting state properties. This material appears to be a strongly coupled, multiband superconductor. H{sub c2}(T) is almost isotropic. De Haas–van Alphen oscillations were observed and two effective masses were estimated from the FFT spectra. Hydrostatic pressure causes a decrease in the superconducting transition temperature at the rate of ≈−0.053 ± 0.001 K/kbar.

  14. Recent Bottomonium Results from BaBar and Belle

    SciTech Connect

    Ziegler, Veronique; /SLAC

    2012-06-25

    Selected studies in bottomonium physics carried out by the BaBar and Belle experiments are presented. They include a study of radiative bottomonium transitions using {gamma} {yields} e{sup +}e{sup -} conversions done by BaBar, the search for the h{sub b}(1P) and h{sub b}(2P) states leading to an evidence for the h{sub b}(1P) seen by BaBar in {Upsilon}(3S) {yields} {pi}{sup 0} h{sub b} decay and to the Belle observation of both the h{sub b}(1P) and the h{sub b}(2P) in the reaction e{sup +}e{sup -} {yields} {pi}{sup +}{pi}{sup -} h{sub b}(1P,2P) from {Upsilon}(5S) data.

  15. Dynamic shape effect in {sup 126}Ba at low spin

    SciTech Connect

    Dewald, A.; Weil, D.; Kruecken, R.; Kuehn, R.; Peusquens, R.; Tiesler, H.; Vogel, O.; Zell, K.O.; von Brentano, P.; Bazzacco, D.; Rossi-Alvarez, C.; Pavan, P.; DeAcuna, D.; De Angelis, G.; De Poli, M. ||

    1996-11-01

    Lifetimes of excited states in {sup 126}Ba have been measured with high precision by means of the GASP spectrometer using the coincidence recoil distance technique. The reaction {sup 100}Mo({sup 30}Si,4{ital n}) {sup 126}Ba at a beam energy of 130 MeV was used. The data were analyzed with the differential decay-curve method (DDCM). The obtained transition quadrupole moments disagree with the predictions of the asymmetric rotor model (ARM), the interacting boson model (IBM), and the general collective model (GCM). They give evidence for a sudden dynamic shape change in {sup 126}Ba between the 4{sup +} and 10{sup +} levels of the ground-state band. {copyright} {ital 1996 The American Physical Society.}

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

    SciTech Connect

    Wu, H.

    1998-02-23

    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{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub 7} solid solution (Gd123ss) in low oxygen partial pressure. Processing of supersaturated Gd{sub 1.2}Ba{sub 1.8}Cu{sub 3}O{sub 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{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub 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{sub 2} for temperature above 608 C, and at lower temperatures the equilibrium second phases are Ba{sub 2}CuO{sub 3.3} and Ba{sub 2}Cu{sub 3}O{sub 5+y}. However, annealing at

  17. Study of F- Production in BaBar RPCs

    SciTech Connect

    Band, H.R.; Bellini, F.; Covarelli, R.; Di Marco, E.; D'Orazio, A.; Ferroni, F.; Li Gioi, L.; Lopez, L.; Polci, F.; /Rome U. /INFN, Rome

    2008-02-22

    The BaBar detector has operated over 200 2nd generation Resistive Plate Chambers (RPCs) in the forward endcap since 2002. Many chambers have increased noise rates and high voltage currents. These aging symptoms are correlated with the integrated RPC current as expected, but also depend on the rate and direction of the gas flow, indicating that pollutants produced in the gas can accelerate aging of downstream RPC surfaces. HF produced by decomposition of the Freon 134a component of the BaBar RPC gas in electric discharges has been proposed as the main pollutant. This paper presents measurements of HF production and absorption rates in BaBar RPCs. Since many of the highest rate chambers in the forward endcap were converted to avalanche mode operation, a comparison of HF production in streamer and avalanche mode RPCs is made. Correlations between the HF production rate and other chamber operating conditions were also explored.

  18. AMiBA: Array for Microwave Background Anisotropy

    NASA Astrophysics Data System (ADS)

    Lo, K. Y.; Chiueh, T. H.; Martin, R. N.; Ng, Kin-Wang; Liang, H.; Pen, Ue-Li; Ma, Chung-Pei

    An Array for Microwave Background Anisotropy (AMiBA) is being built to measure the polarization of the CMB and to survey for high z clusters via the Sunyaev-Zeldovich effect (SZE). AMiBA is a platform mounted 19-element interferometer operating between 85 - 105 GHz, with full polarization capabilities. The aperture size of the elements can be changed between 0.3m and 1.2m, in order to provide a range of fields of view and l-resolution. The platform size is about 10-m so that the resolution can be as high as 1 arc-minute. The sensitivity can be as low as 2 mJy and 7 μK in an hour. The array is to be placed on Mauna Kea in Hawaii or in the Atacama desert in Chile, and is scheduled to be completed in 2003. The current status of AMiBA will be described.

  19. Experimental determination of the partition coefficient for Ba in Neogloboquadrina dutertrei suggests calcification occurs in a Ba-enriched microenvironment

    NASA Astrophysics Data System (ADS)

    Fehrenbacher, J. S.; Russell, A. D.; Davis, C. V.; Spero, H. J.; Chu, E.

    2015-12-01

    The Ba/Ca ratio in several spinose planktic foraminifer species varies as a function of the Ba/Ca concentration of seawater and is not affected by other parameters such as the seawater salinity, temperature and pH (Honisch et al., 2011). Since seawater Ba concentration is linearly related to Ba in nearshore environments, Ba/Ca ratios in spinose species shows promise as an indicator of past changes in monsoon strength and river runoff (e. g. Weldeab et al. 2007). In contrast, the non-spinose foraminifers often have intrashell variability in Ba/Ca, with Ba/Ca ratios much higher than expected for the range of Ba concentrations observed in the ocean. Furthermore, the Ba/Ca ratio can vary by over a factor of 10 within a single specimen. This suggests either 1) the partition coefficient for Ba in non-spinose species differs from that determined for spinose species, or 2) non-spinose species calcify in a micro-environment that is enriched in Ba. We conducted experiments on live specimens to determine the partition coefficient for Ba in the non-spinose foraminifer N. dutertrei. Specimens were collected via plankton net from the Southern California Bight and cultured at the Wrigley Marine Science Center, Santa Catalina Island during the summer of 2013-2015. We use isotopically labeled seawater (87Sr) to identify discrete portions of calcite that grew in culture. We use laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for trace element analyses and to identify ocean grown vs. culture grown calcite. We show that the partition coefficient is similar to the spinose species: N. dutertrei incorporates Ba as a function of seawater chemistry. We conclude from these observations that N. dutertrei forms its calcite from fluids enriched in Ba, and hypothesize that this process occurs via attachment to organic-rich particles such as marine snow.

  20. Bi3+ Luminescence in ABiO2Cl (A = Sr, Ba) and BaBiO2Br

    SciTech Connect

    Porter-Chapman, Yetta D.; Bourret-Courchesne, Edith E.; Derenzo,Stephen E.

    2007-01-18

    Trivalent bismuth luminescence is reported in three Sillenbismuth oxyhalide phases, SrBiO2Cl, BaBiO2Cl, and BaBiO2Br. Thesecompounds exhibit Bi 6s6->6 s2 emission under UV and X-ray radiation.At room temperature, BaBiO2Cl shows the most intense light emission, withspectral and decay properties similar to those found in Bi4Ge3O12 (BGO).At low temperatures, each phase show an increase in the photoluminescenceintensities and a narrowing of the emission peaks. In contrast to thetemperature dependence of BGO, X-ray excited luminescence intensities ofall three phases remain relatively constant throughout the temperaturerange 10 - 295 K. This result indicates that the Sillen phases undergoless thermal quenching than BGO. The low temperature and room temperatureradio-luminescence decay times were determined from pulsed x-raymeasurements. At room temperature, SrBiO2Cl exhibits faster decays thanBGO, while, BaBiO2Cl and BaBiO2Br have decay times similar toBGO.

  1. Soft x-ray spectroscopy of Ba24Ge100: electronic phase transition and Ba-atom rattling.

    PubMed

    Rachi, Takeshi; Kitajima, Masaki; Kobayashi, Kensuke; Guo, FangZhun; Nakano, Takehito; Ikemoto, Yuka; Kobayashi, Keisuke; Tanigaki, Katsumi

    2005-08-15

    The electronic states of Ba24Ge100 are studied by soft x-ray photoelectron spectroscopy (XPS) at a high-energy photon factory. A large reduction in the density of states (DOS) at the Fermi level is clearly shown before and after the electronic phase transition at 200 K. The changes in the spectrum widths and the fine structures of the core-level Ba 4d spectra give a very reasonable indication of the Ba-atom rattlings in the clathrate polyhedra. On-resonance experiments using the excitation from Ba 3d to 4f levels display that the wave functions of Ba 5d and 6s orbitals give only a small contribution to make a Fermi surface through the hybridization with the Ge20 cluster orbitals. Importantly, reliable values of the DOS at the Fermi level NEF are successfully deduced, using two data sets of DOS obtained from high-resolution XPS and the total magnetic susceptibilities by a superconducting quantum interference device, to be 0.149 and 0.0427 states eV(-1) (Ge atom)(-1) for a high-temperature and for a low-temperature phase.

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

    SciTech Connect

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

    2007-10-25

    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.

  3. New insights into the application of the valence rules in Zintl phases-Crystal and electronic structures of Ba7Ga4P9, Ba7Ga4As9, Ba7Al4Sb9, Ba6CaAl4Sb9, and Ba6CaGa4Sb9

    NASA Astrophysics Data System (ADS)

    He, Hua; Stoyko, Stanislav; Bobev, Svilen

    2016-04-01

    Crystals of three new ternary pnictides-Ba7Al4Sb9, Ba7Ga4P9, and Ba7Ga4As9 have been prepared by reactions of the respective elements in molten Al or Pb fluxes. Single-crystal X-ray diffraction studies reveal that the three phases are isotypic, crystallizing in the orthorhombic Ba7Ga4Sb9-type structure (space group Pmmn, Pearson symbol oP40, Z=2), for which only the prototype is known. The structure is based on TrPn4 tetrahedra (Tr=Al, Ga; Pn=P, As, Sb), connected in an intricate scheme into 1D-ribbons. Long interchain Pn-Pn bonds (dP-P>3.0 Å; dAs-As>3.1 Å; dSb-Sb>3.3 Å) account for the realization of 2D-layers, separated by Ba2+ cations. Applying the classic valance rules to rationalize the bonding apparently fails, and Ba7Ga4Sb9 has long been known as a metallic Zintl phase. Earlier theoretical calculations, both empirical and ab-initio, suggest that the possible metallic properties originate from filled anti-bonding Pn-Pn states, and the special roles of the "cations" in this crystal structure. To experimentally probe this hypothesis, we sought to synthesize the ordered quaternary phases Ba6CaTr4Sb9 (Tr=Al, Ga). Single-crystal X-ray diffraction work confirms Ba6.145(3)Ca0.855Al4Sb9 and Ba6.235(3)Ca0.765Ga4Sb9, with Ca atoms preferably substituting Ba on one of the three available sites. The nuances of the five crystal structures are discussed, and the chemical bonding in Ba7Ga4As9 is interrogated by tight-binding linear muffin-tin orbital calculations.

  4. Distributed Online Conditions Database of the BaBar Experiment

    SciTech Connect

    Khan, A.; Gaponenko, I.A.; Brown, D.N.; /LBL, Berkeley

    2011-11-21

    This paper presents CDB - The distributed Conditions Database of the BaBar Experiment. CDB is the second major iteration of the database deployed in BaBar for production use as of October 2002. It replaced the original version of the database used through the first three years of the data taking. The new design and its implementation aims to improve the performance and scalability of the original database and addresses the emerging challenges of the distributed data production and analysis system of the Experiment.

  5. Reaction kinetics and magnetic properties of Ba and Sr ferrites

    NASA Astrophysics Data System (ADS)

    Melzer, K.; Martin, A.; Klink, T.; Wartewig, P.

    1992-04-01

    This Mössbauer study is concerned with the formation mechanism of hexaferrites (n=6) and of monoferrites (n=1) in the systems (1) BaCO3+nFe2O3, (2) SrCO3+nFe2O3 and (3) 0.5BaCO3+0.5SrCO3+nFe2O3. With a molar ratio of 1∶1 for the starting materials one gets final reaction products with different crystalline structures. The experimental results indicate that the thermodynamical final state of the hexaferrite formation is reached on different routes. Various reaction models are discussed.

  6. The Danish Microbiology Database (MiBa) 2010 to 2013.

    PubMed

    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.

  7. Electron microscopy of a Gd-Ba-Cu-O superconductor

    NASA Technical Reports Server (NTRS)

    Ramesh, R.; Thomas, G.; Meng, R. L.; Hor, P. H.; Chu, C. W.

    1989-01-01

    An electron microscopy study has been carried out to characterize the microstructure of a sintered Gd-Ba-Cu-O superconductor alloy. The GdBa2Cu3O(7-x) phase in the oxygen annealed sample is orthorhombic, while in the vacuum annealed sample it is tetragonal. It is shown that the details of the fine structure in the 001-line zone axis convergent beam patterns can be used to distinguish between the orthorhombic form and the tetragonal form. In addition to this matrix phase, an amorphous phase is frequently observed at the triple grain junctions. Gd-rich inclusions have been observed inside the matrix phase.

  8. Observing the CMB with the AMiBA

    NASA Astrophysics Data System (ADS)

    Subrahmanyan, R.

    I discuss the capabilities and limitations of the AMiBA for imaging CMB anisotropies. Michael Kesteven (ATNF-CSIRO) has proposed drift-scanning as an observing strategy for measuring and rejecting any instrumental response that the close-packed interferometers may have to the local environment. The advantages of mosaic imaging CMB anisotropies using a co-mounted interferometric array in a drift-scanning observing mode are discussed. A particular case of mosaic imaging a sky strip using a two-element AMiBA prototype interferometer is considered and the signal-to-noise ratio in the measurement of sky anisotropy using this observing strategy is analysed.

  9. Magnetic characterization of Ca substituted Ba and Sr hexaferrites

    NASA Astrophysics Data System (ADS)

    Asti, G.; Carbucicchio, M.; Deriu, A.; Lucchini, E.; Slokar, G.

    1980-04-01

    A magnetic characterization has been worked out for the solid solution from Ba and Sr hexaferrites (BaFe 1 2O 1 9, SrFe 1 2O 1 9) towards CaO- xFe 2O 3 (2 ⪕ x ⪕5.5). Measurements of Curie temperature, saturation magnetization, magnetic anisotropy, together with Mössbauer characterization indicate that the intrinsic properties of the studied compounds do not change appreciably with increasing Ca content. These results, together with the X-ray data, are consistent with the formation of an undistorted M-type cell with a low content of iron and oxygen vacancies.

  10. Search for cluster radioactivity of {sup 114}Ba

    SciTech Connect

    Oganesyan, Yu.Ts.; Mikheev, V.L.; Tret`yakova, S.P.; Kharitonov, Yu.P.; Yakushev, A.B.; Timokhin, S.N.; Ponomarenko, V.A.; Golovchenko, A.N.

    1994-07-01

    The possibilities of experimental verification of theoretical predictions for cluster-decay probabilities in a new nuclear region near the shells with Z=50 and N=50 are considered. The experiments on production of {sup 114}Ba in the nuclear reaction {sup 58}Ni({sup 58}Ni, 2n) are carried out. The detected {sup 12}C particles can be formed as a result of the cluster decay {sup 114}Ba {yields} {sup 12}C with a branching ratio of 10{sup {minus}4} - 10{sup {minus}5}. 14 refs., 4 figs.

  11. X-ray absorption spectroscopy study in the BaFe2As2 family

    NASA Astrophysics Data System (ADS)

    Koh, Yoonyoung; Kim, Yeongkwan; Yang, Wanli; Kim, Changyoung

    2012-02-01

    One of the representative Fe-based superconductor families, BaFe2As2 (Tc =38K) is a semimetal with the same number of hole and electron carriers, and is in a spin density wave state below 139K. It has been reported that various types of ``doped'' BaFe2As2 systems can obtained by substitution of Ba, Fe, and As atoms. However, an important issue has been recently raised regarding whether each type of substitution indeed induces effective charge doping or not. It is essential to clarify whether each type of substitution indeed induce an effective doping in BaFe2As2 system. To clarify the carrier doping issue, we performed high resolution X-ray absorption spectroscopy experiment on Ba(Fe,Co)2As2, Ba(Fe,Ru)2As2, BaFe2(As,P)2 which are representative ``doped'' BaFe2As2 systems.

  12. A thermodynamic study of BaO + BaCl2 + Cr2O3 fluxes used for the removal of phosphorus from chromium-containing iron melts

    NASA Astrophysics Data System (ADS)

    Inouye, T. K.; Fujiwara, H.; Ichise, E.; Iwase, M.

    1994-10-01

    Electrochemical measurements with solid-oxide galvanic cell of the type Mo/Mo + MoO2//ZrO2(MgO)//{Cu + Cr}alloy + (Cr2O3)slag/Mo were conducted at 1473 K in order to obtain the activities of Cr2O3 in BaO + BaCl2 + Cr2O3 slags used for dephosphorization of chromium-containing iron melts. Based on the activity measurements, it is concluded that in the system BaO + BaCl2 + Cr2 O3 at 1473 K, there are 1 two-phase region in saturation with pure Cr2O3(s) and 3 three-phase regions. The activities of Cr2O3 within such three-phase regions decrease with an increase in BaO/BaCl2 mole ratios. The Cr2O3 activities in BaO + BaCl2 + Cr2O3 fluxes are, in general, greater than those in CaO + CaCl2 + Cr2O3, corresponding to much more effective dephosphorization by BaO + BaCl2 + Cr2O3 fluxes rather than CaO + CaCl2 + Cr2O3 slag.

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

    SciTech Connect

    Mączka, Mirosław; Szymborska-Małek, Katarzyna; Gągor, Anna; Majchrowski, Andrzej

    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.

  14. Structure and physical properties of the barium niobium sulfides BaNbS{sub 3} and BaNb{sub 0.8}S{sub 3-{delta}}

    SciTech Connect

    Kim, Sung-Jin; Bae, Hyun-Sook; Yee, Kyeong-Ae; Choy, Jin-Ho; Kim, Dong-Kuk; Hur, Nan-Hwi

    1995-03-01

    BaNb{sub 0.8}S{sub 3-{delta}} and BaNbS{sub 3} were prepared by heating desired amounts of BaCO{sub 3} and Nb{sub 2}O{sub 5} under CS{sub 2}/N{sub 2} flow. The authors found that nominal composition of BaNb{sub 0.8}S has sulfur defect, and therefore should be written as BaNb{sub 0.8}S{sub 3-{delta}}. XANES experiments of Nb K-edges and XPS experiments proved that the oxidation state of Nb is the same in BaNb{sub 0.8}S{sub 3-{delta}} and BaNbS{sub 3}. To understand their structures, the electronic and physical properties of the BaMX{sub 3} (M = V, Nb, X = S; M = Ta, X = S, Se) phases are compared. In spite of their structural similarity, they exhibit rather different physical properties. It has been known that BaVS{sub 3} is a metal and undergoes a metal to semiconductor transition at 130 K, and this phase shows the ferro/antiferromagnetic transition at a lower temperature. However, BaNbS{sub 3} and BaTaS{sub 3} are diamagnetic semiconductors at room temperature. The major factor stabilizing the semiconducting state for BaTaX{sub 3} and BaNbS{sub 3} may be a large spin-orbit coupling rather than a structural distortion.

  15. Microstructural evolution and electrical properties of base-metal electroded BaTi4O9 materials with B-Si-Ba-Zn-O glass system.

    PubMed

    Chou, Chen-Chia; Su, Yu-Hsuan; Liu, Ze-Ming; Utami, Brianti Satrianti; Chen, Cheng-Sao; Chu, Li-Wen

    2012-09-01

    Barium titanate-based microwave dielectrics usually require relatively high temperatures to sinter, which prevents the use of base metals such as copper for electrodes. In this work, BaTi(4)O(9) microwave dielectric ceramics co-fired with copper electrodes are made possible by adding B-Si-Ba- Zn-O glass to induce liquid-phase sintering at sufficiently low temperature and in reduced atmosphere. The microstructures and electric properties of the BaTi(4)O(9) ceramics thus obtained are carefully examined and studied. Proper glass composition may significantly facilitate mass transportation in the low-temperature co-fired ceramic (LTCC) material, resulting in better densification without serious degradation of electric properties. Although the B2O3/SiO2 ratio enhances the glass mobility during sintering, the BaO/ZnO ratio contributes to the chemical affinity of glass to BaTi(4)O(9) ceramics. In addition, various Ba-Ti-O phases with different Ba/Ti ratios may be found in the specimen through the X-ray diffraction patterns when the BaO/ZnO ratio is varied. If the BaO/ZnO ratio is high and the glass flows easily in the material, the Ba(4)Ti(13)O(30) phase is formed. If the BaO/ZnO ratio is low and the glass flows easily in the material, the BaTi(6)O(13) phase appears. We find that glass-induced Ba(4)Ti(13)O(30) transformation may significantly decrease Qxf values in the BT4-BSBZ materials. Therefore, the appropriate glass composition must be selected to ensure the phase stability of dielectrics to achieve the best performance possible.

  16. Nonlinearity parameter B/A of biological tissue ultrasound imaging in echo mode

    SciTech Connect

    Toulemonde, M. Varray, F.; Bernard, A.; Basset, O.; Cachard, C.

    2015-10-28

    The nonlinearity B/A parameter influences the distortion of ultrasound waves during their propagation in tissue. Normal and pathological media have different B/A values and this parameter may be used to characterize them. In this paper the multitaper coherent plane wave compounding (MCPWC) is combined with the extended comparative method (ECM) to estimate the B/A parameter in simulation and acquisition. Using plane wave transmission and orthogonal apodization during beam forming improves the B/A estimation and delineation.

  17. Behavior of BaBr2, BaI2, and BaCl2 at high pressure as analogs to SiO2.

    NASA Astrophysics Data System (ADS)

    Smart, T. J.; Stackhouse, S.; Diamond, M. R.; Godwal, B. K.; Jeanloz, R.

    2015-12-01

    Motivated by the expectation that giant and supergiant planets likely contain rocky components in their cores, we study analogs of the archetypal rock constituent, SiO2. The crystal structures of SiO2 under ultra-high pressures, greater than feasible experimental conditions, are believed to be documented by the high pressure structural sequence of AX2 compounds. Experimental and theoretical work agree on a high pressure transition to the cotunnite (orthorhombic) phase, with first-principles theory predicting that SiO2 transforms to the cotunnite structure at 750 GPa. However, the existence of a postcotunnite (monoclinic) phase as the final high pressure polymorph, suggested by X-ray diffraction (XRD) experiments on ambient pressure cotunnite-structured AX2 compounds (e.g. PbCl2, SnCl2), has been challenged by density-functional theory (DFT) computations. This disagreement could perhaps be due to sensitivity in diamond-anvil cell (DAC) experiments to pressure gradients; conversely, it could perhaps arise from limitations of DFT. This study further explores both the experimental and theoretical sides of this debate, with an aim to resolve this discrepancy. We present synchrotron XRD data on the AX2 compounds BaCl2, BaBr2, and BaI2, compressed up to 70 GPa at room temperature in a DAC. Here we compare our experimentally observed crystallography and equations of state with results from our DFT simulations.

  18. Study of B1 (NaCl-type) to B2 (CsCl-type) pressure-induced structural phase transition in BaS, BaSe and BaTe using first-principles computations

    NASA Astrophysics Data System (ADS)

    Khare, Sanjay; Zhou, Xiuquan; Roehl, Jason L.; Lind, Cora

    2013-03-01

    We have studied the pressure-induced phase transitions from NaCl-type (B1) to CsCl-type (B2) structure in BaS, BaSe and BaTe by using ab initio density functional theory computations in the local density approximation. The Buerger and WTM[2] mechanisms were explored by mapping the enthalpy contours in two and four dimensional configuration space for the two mechanisms, respectively. Transition pressures for BaS, BaSe and BaTe were determined to be 5.5 GPa, 4.9 GPa and 3.4 GPa, respectively. From these configuration space landscapes, a low enthalpy barrier path was constructed for the transitions to proceed at three different pressures. We obtained barriers of 0.18, 0.16 and 0.15 eV/pair (17.4, 15.4 and 14.5 kJ/mol) for the Buerger mechanism and 0.13, 0.13 and 0.12 eV/pair (12.5, 12.5 and 11.6 kJ/mol) for the WTM mechanism at the transition pressures for BaS, BaSe and BaTe, respectively, indicating that the WTM mechanism is slightly more favorable in these compounds. We describe the difference of the two mechanisms by differences in their symmetry and atomic coordination. National Science Foundation (#DMR 1005911, #DMR 0705464, #CMMI 1234777 and CNS 0855134), Ohio Supercomputer Center (OSC).

  19. Study of B1 (NaCl-type) to B2 (CsCl-type) pressure-induced structural phase transition in BaS, BaSe and BaTe using ab initio computations

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Roehl, J. L.; Lind, C.; Khare, S. V.

    2013-02-01

    We have studied the pressure-induced phase transitions from NaCl-type (B1) to CsCl-type (B2) structure in BaS, BaSe and BaTe by using ab initio density functional theory computations in the local density approximation. The Buerger and WTM mechanisms were explored by mapping the enthalpy contours in two- and four-dimensional configuration space for the two mechanisms, respectively. Transition pressures for BaS, BaSe and BaTe were determined to be 5.5 GPa, 4.9 GPa and 3.4 GPa, respectively. From these configuration space landscapes, a low enthalpy barrier path was constructed for the transitions to proceed at three different pressures. We obtained barriers of 0.18, 0.16 and 0.15 eV/pair (17.4, 15.4 and 14.5 kJ mol-1) for the Buerger mechanism and 0.13, 0.13 and 0.12 eV/pair (12.5, 12.5 and 11.6 kJ mol-1) for the WTM mechanism at the transition pressures for BaS, BaSe and BaTe, respectively, indicating that the WTM mechanism is slightly more favorable in these compounds. We describe the difference between the two mechanisms by differences in their symmetry and atomic coordination.

  20. Recent Results From BaBar in Tau Physics

    SciTech Connect

    Lewczuk, Mateusz; /Victoria U.

    2009-06-25

    The BaBar collaboration has accumulated over 400 million {tau}-pairs which can be used to study charged leptonic and hadronic weak currents to unprecedented precision. This note presents results on lepton universality, measurements of |V{sub us}|, and searches for {tau} decays which violate lepton flavour conservation, or {tau} decays that proceed through a suppressed second class current.

  1. Recent Measurements of sin2beta at BaBar

    SciTech Connect

    Sciolla, Gabriella; /MIT

    2005-12-14

    The angle {beta} is the most accurately measured quantity that determines the Unitarity Triangle. In this article I review the various measurements of this angle performed by the BaBar Collaboration, and discuss their implications in the search for new physics.

  2. High-spin states in ^122_ 56Ba

    NASA Astrophysics Data System (ADS)

    Chiara, C. J.; Cardona, J.; Fossan, D. B.; Koike, T.; Lafosse, D. R.; Starosta, K.; Ye, Z.; Freeman, S.; Leddy, M.; Smith, J. F.; Wadsworth, R.; Wilson, A. N.; Devlin, M.; Lerma, F.; Sarantites, D. G.; Wilson, J. N.; Carpenter, M. P.; Davids, C. N.; Janssens, R. V. F.; Seweryniak, D.

    2000-10-01

    High-spin states in ^122Ba have been studied via the ^64Zn(^64Zn,α2p) reaction. A 260-MeV ^64Zn beam was provided by the Argonne Tandem/Linac Accelerator System. The emitted γ rays were detected using the Gammasphere array of 101 suppressed Ge detectors. In addition, the Microball charged-particle detector array was used to select the α 2p channel, thus isolating ^122Ba. The level scheme of ^122Ba has been substantially extended from the previously published level scheme of only six γ rays(J. Conrad, Nucl. Phys. A234), 157 (1974).. Six decoupled bands and two strongly-coupled bands have been observed to spins of up to 40hbar. Configuration assignments are made with the aid of the systematic alignment properties of ^122Ba and its neighbors. Octupole deformation is predicted to develop in Z ≈ 56 nuclei due to the occupation of Δ l = Δ j = 3 proton orbitals. Systematics of proposed negative-parity side bands in the A ≈ 120 barium isotopes will be discussed. Comparisons with cranked Nilsson-Strutinsky calculations will also be presented in light of possible smooth band termination properties.

  3. Thin film processing of photorefractive BaTiO3

    NASA Technical Reports Server (NTRS)

    Schuster, Paul R.; Potember, Richard S.

    1991-01-01

    The principle objectives of this ongoing research involve the preparation and characterization of polycrystalline single-domain thin films of BaTiO3 for photorefractive applications. These films must be continuous, free of cracks, and of high optical quality. The two methods proposed are sputtering and sol-gel related processing.

  4. AMiBA-array for microwave background anisotropy

    NASA Astrophysics Data System (ADS)

    Kesteven, M.

    2002-03-01

    AMiBA is a 90 GHz interferometric array of the ASIAA (Academia Sinica, Institue of Astronomy and Astrophysics). It will make a detailed study of the polarization of the CMB anisotropy; it will also undertake a survey of Sunyaev-Zel'dovich clusters. It is under construction at present, with an expected completion date of late 2003. .

  5. AMiBA: Array for Microwave Background Anisotropy

    NASA Astrophysics Data System (ADS)

    Lo, K. Y.; Chiueh, T.; Martin, R. N.

    2000-12-01

    As part of a 4-year US\\ 15 million Cosmology and Particle Astrophysics (CosPA) Research Excellence Initiative in Taiwan, AMiBA - a 19-element dual-channel 85-105 GHz interferometer array is being specifically built to survey for high redshift clusters of galaxies via the Sunyaev-Zeldovich Effect. In addition, the AMiBA will have full polarization capabilities in order to probe the polarization properties of the Cosmic Microwave Background. The AMiBA, to be sited on Mauna Kea in Hawaii or in Chile, will reach a sensitivity of 1.5 mJy or 7\\mu$K in 1 hour. The project involves scientific and technical collaborations with the Australia Telescope National Facilities (ATNF), the Canadian Institute of Theoretical Astrophysics (CITA), the Physics departments of the Carnegie-Mellon University (CMU) and the University of Pennsylvania (UPenn). The construction of the AMiBA is scheduled to be completed in 2003. Current status of the project will be discussed.

  6. Complete Genome Sequence of the Methanogen Methanoculleus bourgensis BA1 Isolated from a Biogas Reactor

    PubMed Central

    Maus, Irena; Wibberg, Daniel; Winkler, Anika; Pühler, Alfred; Schnürer, Anna

    2016-01-01

    Methanoculleus bourgensis BA1, a hydrogenotrophic methanogen, was isolated from a laboratory-scale biogas reactor operating under an elevated ammonium concentration. Here, the complete genome sequence of M. bourgensis BA1 is reported. The availability of the BA1 genome sequence enables detailed comparative analyses involving other Methanoculleus spp. representing important members of microbial biogas communities. PMID:27340059

  7. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 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...

  8. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2010 CFR

    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...

  9. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 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...

  10. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 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...

  11. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 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...

  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

    NASA Technical Reports Server (NTRS)

    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. Co{sub 2}FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

    SciTech Connect

    Rogge, J.; Schmalhorst, J.; Hütten, A.; Hetaba, W.

    2015-07-15

    We succeed to integrate BaO as a tunneling barrier into Co{sub 2}FeAl 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 Co{sub 2}FeAl (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.

  14. Syntheses, crystal structures, and electronic properties of Ba8Si2US14 and Ba8SiFeUS14

    NASA Astrophysics Data System (ADS)

    Mesbah, Adel; Prakash, Jai; Lebègue, Sébastien; Stojko, Wojciech; Ibers, James A.

    2015-10-01

    Black single crystals of the new compounds Ba8Si2US14 and Ba8SiFeUS14 have been obtained by high-temperature solid-state methods at 1223 K. These isostructural compounds crystallize in a new structure type in space group C2h3 - C2/m of the monoclinic system. The salt-like structure comprises isolated US6 octahedra and MS4 tetrahedra separated by Ba cations. The US6 octahedra form pseudo-layers that are separated by two other pseudo-layers formed by isolated MS4 tetrahedra. These compounds do not show any short S-S interactions. Ba8Si2US14 charge balances with 8 Ba2+, 2 Si4+, 1 U4+, and 14 S2-; Ba8SiFeUS14 can be charge balanced with 8 Ba2+, 1 Si4+, 1 Fe3+, 1 U5+, and 14 S2-. DFT calculations using the HSE functional indicate that the compounds are semiconductors. The calculated band gaps are 1.2 eV and 1.8 eV for Ba8Si2US14 and Ba8SiFeUS14, respectively.

  15. Performance of two-pole bandpass filters photodefined on double-sided Y-Ba-Cu-O and Tl-Ba-Ca-Cu-O thin films

    NASA Technical Reports Server (NTRS)

    Miranda, F. A.; Toncich, S. S.; Bhasin, K. B.

    1993-01-01

    The performance of 7.3-GHz two-pole bandpass filters (5% bandwidth) fabricated on double-sided Y-Ba-Cu-O and Tl-Ba-Ca-Cu-O thin films deposited on LaAlO3 is discussed. At 77 K, the Tl-Ba-Ca-Cu-O and Y-Ba-Cu-O superconducting filters exhibited minimum passband insertion losses of 0.3 and 1.2 dB, respectively. An insertion loss of 3.4 dB was measured for an all-gold filter at 77 K.

  16. The effects of BaSO₄ loading on OPC cementing system for encapsulation of BaSO₄ scale from oil and gas industry.

    PubMed

    Hussein, O; Utton, C; Ojovan, M; Kinoshita, H

    2013-10-15

    The BaSO4 scales obtained from piping decontamination from oil and gas industries are most often classified as low level radioactive waste. These wastes could be immobilised by stable cement matrix to provide higher safety of handling, transportation, storage and disposal. However, the information available for the effects of the basic formulation such as waste loading on the fundamental properties is still limited. The present study investigated the effect of BaSO4 loading and water content on the properties of OPC-BaSO4 systems containing fine BaSO4 powder and coarse granules. The BaSO4 with different particle size had a marked effect on the compressive strength due to their different effects on hydration products formed. Introduction of fine BaSO4 powder resulted in an increased formation of CaCO3 in the system, which significantly contributed to the compressive strength of the products. Amount of water was important to control the CaCO3 formation, and water to cement ratio of 0.53 was found to be a good level to maintain a low porosity of the products both for fine BaSO4 powder and coarse BaSO4 granule. BaSO4 loading of up to 60 wt% has been achieved satisfying the minimum compressive strength of 5 MPa required for the radioactive wasteforms. PMID:23911824

  17. Experimental and numerical studies of microwave properties of BaTiO3-Pt composites

    NASA Astrophysics Data System (ADS)

    Kuga, Yasuo; Lee, Seung-Woo; Almajid, Abdulhakim; Taya, Minoru; Li, Jing-Feng; Watanabe, Ryuzo

    2002-10-01

    In this paper, we will present the experimental results of the microwave properties of BaTiO3 and BaTiO3-Pt composites. These composites materials were designed to increase the effective dielectric constant at microwave frequency. Three different platinum volume fractions were used, 3, 5 and 10%, to make BaTiO3-Pt composites, in addition to a pure BaTiO3 material. To characterize the BaTiO3-Pt composites, microwave measurements were conducted using the waveguide transmission measurements. The experimental results verify that it is possible to increase the dielectric constant using the conductor loading method.

  18. Luminescence and site occupancy of Ce3+ in Ba2Ca(BO3)2

    NASA Astrophysics Data System (ADS)

    Lin, Huihong; Liang, Hongbin; Han, Bing; Zhong, Jiuping; Su, Qiang; Dorenbos, Pieter; Birowosuto, M. Danang; Zhang, Guobin; Fu, Yibing; Wu, Wenqing

    2007-07-01

    The phosphors of Ce3+ activated Ba2Ca(BO3)2 with chemical formulas Ba2(1-x)CexNaxCa(BO3)2 and Ba2Ca1-2xCexNax(BO3)2 were prepared. The luminescence properties have been investigated under vacuum ultraviolet UV and x-ray excitation. Though the point defects CeBa• and NaBa' are expected to occur in samples Ba2(1-x)CexNaxCa(BO3)2 , and CeCa• and NaCa' are expected to appear in samples Ba2Ca1-2xCexNax(BO3)2 according to the formulas of the compounds, however, two types of Ce3+ centers were found in all samples due to the occupancy of both Ba2+ and Ca2+ sites. So the influence of doping concentration on the preferential site occupancy was studied, and it was found that Ce3+ ions always preferentially enter Ba2+ sites at low doping concentration for both samples Ba2(1-x)CexNaxCa(BO3)2 and Ba2Ca1-2xCexNax(BO3)2 . In addition, the 5d energy levels and decay behaviors for Ce3+ in Ba2+ and Ca2+ sites, the concentration quenching, and the x-ray excited photon output were evaluated to clearly reveal the luminescence features.

  19. Progress Towards Measurement of the Anapole Moment of 137 Ba19 F

    NASA Astrophysics Data System (ADS)

    Cahn, Sidney; Altuntas, Emine; Demille, David; Kozlov, Mikhail

    2016-05-01

    Weak interactions inside the nucleus produce a toroidal current distribution around the axis of nuclear spin. This current distribution, known as the nuclear anapole moment is the dominant source of nuclear spin-dependent parity violation (NSD-PV) effects for nuclei with nucleon number A >= 20.We propose to measure the anapole moment of 137 Ba19 F. To diagnose systematics and establish a measurement sequence we use 138 Ba19 F, which has negligible NSD-PV effects. 138 Ba19 F has a larger isotopic abundance and fewer hyperfine levels compared to those of 137 Ba19 F. Therefore fluorescence signals from 138 Ba19 F are approximately 26 times larger than those from 137 Ba19 F. Here we present planned improvements to our apparatus, including a magnetic hexapole lens to improve the molecular beam flux and preliminary spectroscopy measurements with 137 Ba19 F.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Growth and transport properties of Y-Ba-Cu-O/Pr-Ba-Cu-O superlattices

    SciTech Connect

    Lowndes, D.H.; Norton, D.P.; Budai, J.D.; Christen, D.K.; Klabunde, C.E.; Warmack, R.J.; Pennycook, S.J.

    1990-01-01

    The pulsed-laser deposition method has been used to fabricate epitaxial, nonsymmetric M(Y) {times} N(Pr) superlattices in which YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) layers either M = 1,2,3,4,8, or 16 c-axis unit cells thick are separated by insulating PrBa{sub 2}Cu{sub 3}O{sub 7-x} (PBCO) layers N unit cells thick (N = 1 to {approximately}32). The zero-resistance superconducting transition temperature, T{sub c0}, initially decreases rapidly with increasing PBCO layer thickness, but then saturates at T{sub c0} {approximately} 19 K, 54 K, 71 K, or 80 K, or structures containing 1-,2-,3-, or 4-cell-thick YBCO layers, respectively. Critical current density measurements carried out on structures with 16- or 32-cell thick YBCO layers show that the magnitude of J{sub c}(H = 0) {approximately} 1-2 MA/cm{sup 2}, as well as the magnetic field dependence and the anisotropy of J{sub c}(H) all are in good agreement with corresponding measurements on thicker, single-layer YBCO films. Thus, there is no evidence of an enhanced J{sub c}(H) due to the multi-layered structure, for the layer thickness investigated to date. The systematic variation of T{sub c0}, as a function of the YBCO and PBCO layer thickness, is discussed in light of other recent experiments and theoretical model calculations. The superlattices' structural and compositional order are characterized using x-ray diffraction, transmission electron microscopy, and scanning tunneling microscopy, and details of the pulsed-laser deposition process are reported. 42 refs., 7 figs.

  2. Superconductivity in the Graphite Intercalation Compound BaC(6).

    PubMed

    Heguri, Satoshi; Kawade, Naoya; Fujisawa, Takumi; Yamaguchi, Akira; Sumiyama, Akihiko; Tanigaki, Katsumi; Kobayashi, Mototada

    2015-06-19

    Among many two-dimensional (2D) high T(C) superconductors, graphite intercalation compounds (GICs) are the most famous intercalation family, which are classified as typical electron-phonon mediated superconductors. We show unambiguous experimental facts that BaC(6), the superconductivity of which has been missing for many years so far among various alkaline earth metal (Ca, Sr, and Ba) intercalted GICs, exhibits superconductivity at T(C)=65  mK. By adding this finding as the additional experimental point, a complete figure displaying the relationship between T(C) and interlayer distance (d) for GICs is now provided, and their possible superconducting mechanisms raised so far are revisited. The present study settles a long-running debate between theories and experiments on the superconductivity in the first stage GICs.

  3. BaMn2Sb2: A New Semiconducting Ferromagnet

    NASA Astrophysics Data System (ADS)

    Li, Jianneng; Stadler, S.; Karki, A.; Xiong, Y.; Jin, R.

    2012-02-01

    We have grown high-quality single crystals of BaMn2Sb2, which possesses the ThCr2Si2 structure as determined by X-ray powder diffraction technique. Magnetization measurements indicate that BaMn2Fe2 is ferromagnetic below TC = 580K. On the other hand, the temperature dependence of electrical resistivity shows semiconducting behavior, which can be described by thermally-activated resistivity formula with thermal activation energy about 0.25 eV . While the Hall coefficient has positive sign between 2 and 300 K, the Seebeck Coefficient undergoes sign change from positive at high temperatures to negative at low temperatures, reaching -260 μV/K at 70 K. The implication will be discussed.

  4. AMiBA: Broadband Heterodyne Cosmic Microwave Background Interferometry

    NASA Astrophysics Data System (ADS)

    Chen, Ming-Tang; Li, Chao-Te; Hwang, Yuh-Jing; Jiang, Homin; Altamirano, Pablo; Chang, Chia-Hao; Chang, Shu-Hao; Chang, Su-Wei; Chiueh, Tzi-Dar; Chu, Tah-Hsiung; Han, Chih-Chiang; Huang, Yau-De; Kesteven, Michael; Kubo, Derek; Martin-Cocher, Pierre; Oshiro, Peter; Raffin, Philippe; Wei, Tashun; Wang, Huei; Wilson, Warwick; Ho, Paul T. P.; Huang, Chih-Wei; Koch, Patrick; Liao, Yu-Wei; Lin, Kai-Yang; Liu, Guo-Chin; Molnar, Sandor M.; Nishioka, Hiroaki; Umetsu, Keiichi; Wang, Fu-Cheng; Wu, Jiun-Huei Proty

    2009-04-01

    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.

  5. Dynamic moments of inertia in Xe, Cs and Ba nuclei

    SciTech Connect

    El-Samman, H.; Barci, V.; Gizon, A.; Gizon, J.; Hildingsson, L.; Jerrestam, D.; Klamra, W.; Kossakowski, R.; Lindblad, T.; Gono, Y.; Bengtsson, T.; Leander, G.A.

    1984-01-01

    The ..gamma..-rays following the reactions induced by /sup 12/C ions on /sup 115/In, /sup 112/,/sup 117/,/sup 122/Sn and /sup 123/Sb targets have been investigated using six NaI(Tl) detectors in a two-dimensional arrangement. The collective moment of inertia I(/sup 2/) /sub band/ of /sup 118/,/sup 122/Xe, /sup 123/Cs and /sup 128/,/sup 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(/sup 2/)/sub eff/ of /sup 118/Xe and /sup 130/Ba measured by sum-spectrometer techniques. 13 references.

  6. New States and Charmonium Spectroscopy at BaBar

    SciTech Connect

    Dunwoodie, W.; /SLAC

    2011-12-06

    Several charmonium-like states above D{bar D} threshold have been discovered at the Belle and BaBar B-factories. Some are produced via Initial State Radiation (e.g. Y(4260) and Y(4350)), and some are observed in B meson decays (e.g. X(3872), Y(3940), and Z-(4430)). The Z-(4430) state has generated a great deal of interest, having minimum quark content (c{bar c}d{bar u}) and, thus, representing the unequivocal manifestation of a four-quark meson state. Here we summarize recent BaBar results on the Y(4260), X(3872), Y(3940), and on a search for the Z-(4430).

  7. Luminescence in Li2BaP2O7.

    PubMed

    Hatwar, L R; Wankhede, S P; Moharil, S V; Muthal, P L; Dhopte, S M

    2015-09-01

    The photo-, thermo- and optically stimulated luminescence in Li2BaP2O7 activated with Eu(2+) /Cu(+) are reported. Strong thermoluminescence, which is about two times greater than LiF-TLD 100 was observed in the Eu(2+) -activated sample. It also exhibited optically stimulated luminescence sensitivity of ~20% that of commercial Al2O3:C phosphor. PMID:25351563

  8. Primary lithium organic electrolyte battery BA-5557( )/U

    NASA Astrophysics Data System (ADS)

    Raman, N.

    1982-01-01

    The BA-5557( )/U is a lithium-sulfur dioxide type battery especially designed for constant power devices; this 30-volt battery has Li/SO2 coulombic fuel ratio of approximately 0.9, contains two (2) replaceable 8/10 amp slo-blo fuses and has a capacity of 2.5 Ah at c/4 rate at 70 degrees F. The battery case consists of a flame retardant ABS material.

  9. Analysis of Jupiter's Oval BA: A Streamlined Approach

    NASA Technical Reports Server (NTRS)

    Sussman, Michael G.; Chanover, Nancy J.; Simon-Miller, Amy A.; Vasavada, Ashwin R.; Beebe, Reta F.

    2010-01-01

    We present a novel method of constructing streamlines to derive wind speeds within jovian vortices and demonstrate its application to Oval BA for 2001 pre-reddened Cassini flyby data, 2007 post-reddened New Horizons flyby data, and 1998 Galileo data of precursor Oval DE. Our method, while automated, attempts to combine the advantages of both automated and manual cloud tracking methods. The southern maximum wind speed of Oval BA does not show significant changes between these data sets to within our measurement uncertainty. The northern maximum dries appear to have increased in strength during this time interval, tvhich likely correlates with the oval's return to a symmetric shape. We demonstrate how the use of closed streamlines can provide measurements of vorticity averaged over the encircled area with no a priori assumptions concerning oval shape. We find increased averaged interior vorticity between pre- and post-reddened Oval BA, with the precursor Oval DE occupying a middle value of vorticity between these two.

  10. Photoreduction of Sm(3+) in Nanocrystalline BaFCl.

    PubMed

    Riesen, Nicolas; François, Alexandre; Badek, Kate; Monro, Tanya M; Riesen, Hans

    2015-06-18

    We demonstrate that exposure of nanocrystalline BaFCl:Sm(3+) X-ray storage phosphor to blue laser pulses with peak power densities on the order of 10 GW/cm(2) results in conversion of Sm(3+) to Sm(2+). This photoreduction is found to be strongly power-dependent with an initial fast rate, followed by a slower rate. The photoreduction appears to be orders of magnitude more efficient than that for previously reported systems, and it is estimated that up to 50% of the samarium ions can be photoreduced to the divalent state. The main mechanism is most likely based on multiphoton electron-hole creation, followed by subsequent trapping of the electrons in the conduction band at the Sm(3+) centers. Nanocrystalline BaFCl:Sm(3+) is an efficient photoluminescent X-ray storage phosphor with possible applications as dosimetry probes, and the present study shows for the first time that the power levels of the blue light have to be kept relatively low to avoid the generation of Sm(2+) in the readout process. A system comprising the BaFCl:Sm(3+) nanocrystallites embedded into a glass is also envisioned for 3D memory applications.

  11. Metabolism and DNA binding of BaP in the presence of complex organic mixtures

    SciTech Connect

    Springer, D.L.; Dankovic, D.A.; Thomas, B.L.; Hopkins, K.L.; Bean, R.E.; Mahlum, D.D.

    1986-04-01

    Previous studies have shown that the mutagenic, carcinogenic and DNA binding activities of benzo(a)pyrene (BaP) were decreased when BaP was coadministered with complex organic mixtures. We have continued these studies to identify the components of the mixture that were responsible for this effect. For this study a high-boiling coal liquid was separated into aliphatic, polycyclic aromatic hydrocarbon (PAH), nitrogen-containing polycyclic aromatic compounds (NPAC) and oxygen containing PAH fractions (HPAH); these were spiked with /sup 3/H-BaP, administered dermally to mice and DNA isolated twenty-four hours later. Binding of BaP, as estimated by radioactivity associated the DNA, decreased to 47, 55 and 66% of that for the same dose of BaP alone for the PAH, NPAC and HPAH fractions, respectively. In vitro studies with Aroclor-induced rat liver S9 demonstrated that the rate of metabolism of BaP decreased when it was coadministered with the mixtures but that the BaP metabolite profiles were similar for BaP alone and in the presence of the mixture. These data suggest that the differences in mutagenic, and presumable carcinogenic activities, for BaP, when administered with the complex mixture, were due to decreased rates of conversion of BaP to reactive metabolites. 15 refs., 2 figs., 3 tabs.

  12. Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl: Interesting size effects originated from the tetrahedral anions

    SciTech Connect

    Pan, Ming-Yan; Xia, Sheng-Qing Liu, Xiao-Cun; Tao, Xu-Tang

    2014-11-15

    Two new barium chalcogenides, Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl, were synthesized by using high temperature solid-state reactions and their structures were determined by single-crystal X-ray diffraction technique. Despite the similar chemical formula, the structures of Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl are subtly different due to the size effects originated from the tetrahedral anions. Ba{sub 3}GeS{sub 5} crystallizes in the orthorhombic space group Pnma (no. 62) with cell parameters of a=12.0528(9) Å, b=9.5497(7) Å and c=8.5979(6) Å, while Ba{sub 3}InS{sub 4}Cl adopts a different tetragonal system (space group: I4/mcm, no. 140, a=b=8.3613(6) Å, c=14.3806(18) Å). The measured optical band gap of Ba{sub 3}GeS{sub 5} is 3.0 eV, a little smaller than the value of 3.42 eV in Ba{sub 3}InS{sub 4}Cl. Theoretical calculations by Wien2k are provided as well in order to better understand these results. - Graphical abstract: The polyhedral structure view for Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl in which Ba, S and Cl atoms are plotted in purple, red and green spheres. - Highlights: • Two new barium chalcogenides, Ba{sub 3}GeS{sub 5} and Ba{sub 3}InS{sub 4}Cl, were synthesized from the BaCl{sub 2}-flux reactions. • Their crystal structures feature discrete [MS{sub 4}] tetrahedra which embody interesting size effects. • Both compounds exhibit a band gap around 3.0 eV. • They are thermally stable up to 1073 K.

  13. Electric characterization of (Sr, Sr-Ba, Ba) M-type ferrites by AC measurements[Alternating Current

    SciTech Connect

    Huanosta-Tera, A.; Lira-Hueso, R. de; Perez-Orta, O.; Palomares-Sanchez, S.A.; Ponce-Castaneda, S.; Mirabal-Garcia, M.

    2000-02-01

    Considering the electrical conductivity in ceramics, necessary reference should be given to dynamic processes occurring as a function of frequency and temperature. Although the most immediate interest in ferrites lies in their magnetic properties, technological applications require a wider knowledge of general physical properties as well. This is especially applicable when the materials are studied as a function of composition or when adding different modifiers. In this report, the authors present results of the ac and dc electric characteristics of a family of magneto-plumbite-type hexaferrites, where Ba gradually substitutes Sr in the Ba{sub x}Sr{sub 1{minus}x}Fe{sub 12}O{sub 19} compound (0 {le} x {le} 1). The results were determined over a wide range of frequencies and temperatures.

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

    PubMed Central

    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. PMID:26618713

  15. Advective excess Ba transport as shown from sediment and trap geochemical signatures

    SciTech Connect

    Fagel, N.; Andre, L.; Dehairs, F.

    1999-08-01

    The authors report the results of a geochemical study of sediment and trap material. Major and trace elements (Zr, Ba, rare earth elements, and Th) were analyzed on bulk sedimentary material collected along the NE Atlantic margin. The aim is to test the widespread use of Ba-barite as a proxy for paleoproductivity in a continental margin area. This environment is of great interest because atmospheric-oceanic exchanges are important. In sediments, the geochemical signatures remain close to an upper crust reference, with flat shale-normalized rare earth elements patterns and constant elementary ratios. The calculated biogenic fraction of Ba or excess Ba (20--45%) remains lower than the excess Ba record in trap material (80--99%). The evolution of the geochemical signature along the margin reflects variable dilution of a detrital Post Archean Australian Shale-like component by a biogenic carbonaceous seawater-derived component. The trap material displays a wide range of variation in its trace element content (e.g., Ba {approximately}150--3,000 ppm, Zr {approximately}2--100 ppm), except for the abyssal site, which is characterized by constant signature. In the two other sites, all of the trace element contents increase with water depth and present pronounced seasonal changes at each sampled water depth. The amount of excess Ba also increases in the deepest traps, and its evolution throughout the year mimics the change of the other analyzed trace elements. In contrast, its relationships with particulate organic carbon are not obvious. In terms of fluxes, two periods of enhanced excess Ba fluxes are observed: (1) excess Ba flux increases with the detrital-like elements like Th especially during winter, and (2) excess Ba flux is enhanced without any change for the other trace elements during spring. To explain the first case, a supply through lateral advection is proposed. Such transient input of significant excess Ba flux will have a great impact on the yearly averaged

  16. Electrical and Optical Property of Ferroelectric BaTiO3:Eu

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon; Grichener, Alexander; Jensen, Jacob; Choi, Sang H.

    2005-01-01

    We studied various electrical and optical properties of Europium (1 atomic %) incorporated BaTiO3 film on n-Si(100) substrate. The thin film structure was analyzed by X-ray diffraction. Film thickness and optical refractive index were measured with an ellipsometer. P-E hysteresis measurement shows the remnant polarization of 37 micro C/sq cm in BaTiO3:Eu film. C-V measurements on the pure BaTiO3 film show recovery of capacitance across sweeping voltage ranges with a narrow transition zone due to the polarization change. On the other hand, C-V and I-V measurements on the BaTiO3:Eu film show that Europium incorporation increases positively charged states in the BaTiO3 layer such that BaTiO3:Eu/n-Si interface behaves like a leaky p-n junction.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Synthesis, characterization of polyaniline/BaFe 12O 19 composites with microwave-absorbing properties

    NASA Astrophysics Data System (ADS)

    Ting, Tzu-Hao; Wu, Kuo-Hui

    2010-08-01

    Polyaniline/BaFe 12O 19 (PANI/Ba ferrite) composites were synthesized by in situ polymerization at different aniline/Ba ferrite weight ratios (Ani/Ba ferrite=1/2, 1/1 and 2/1) and introduced into epoxy resin to be microwave absorber. The spectroscopic characterizations of the formation processes of PANI/Ba ferrite composites were studied using Fourier transform infrared, ultraviolet-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron spin resonance. Microwave-absorbing properties were investigated by measuring complex permittivity, complex permeability and reflection loss in the 2-18 and 18-40 GHz microwave frequency range using the free space method. The results showed that a wider absorption frequency range could be obtained by adding different polyaniline contents in Ba ferrite.

  19. Interfacial reactions and microstructure of BaTiO 3 films prepared using fluoride precursor method

    NASA Astrophysics Data System (ADS)

    Fujihara, Shinobu; Schneller, Theodor; Waser, Rainer

    2004-01-01

    Interfacial reactions of BaF 2 and TiO 2 were investigated in preparing BaTiO 3 thin films using a fluoride precursor method. Trifluoroacetate solutions were prepared from barium acetate, titanium tetraisopropoxide (TTIP), and trifluoroacetic acid (TFA, CF 3COOH) with additives such as water and acetylacetone. The solutions were deposited on platinized Si wafers by spin-coating, were pyrolysed at 400 °C in air and were finally heated typically at 700 °C in a water vapor atmosphere. The perovskite BaTiO 3 phase was obtained although a small portion of BaF 2 remained unreacted. Thus, the films were characterized as the mixture of BaTiO 3, BaF 2, and amorphous TiO 2. Influence of the solution chemistry on the phase evolution and microstructure was examined in order to discuss the reaction pathway of the perovskite phase.

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

    SciTech Connect

    Li, X.; Bai, Y.; Su, Y. J.; Wang, B. C.

    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.

  1. Reflection Asymmetric Shapes in the Neutron-Rich 140,143Ba Isotopes

    NASA Astrophysics Data System (ADS)

    Zhu Sheng-jiang (S, J. Zhu; Wang, Mu-ge; J, H. Hamilton; A, V. Ramayya; B, R. S. Babu; W, C. Ma; Long, Gui-lu; Deng, Jing-kang; Zhu, Ling-yan; Li, Ming; T, N. Ginter; J, Komicki; J, D. Cole; R, Aryaeinejad; Y, K. Dardenne; M, W. Drigert; J, O. Rasmussen; Ts, Yu Oganessian; M, A. Stoyer; S, Y. Chu; K, E. Gregorich; M, F. Mohar; S, G. Prussin; I, Y. Lee; N, R. Johnson; F, K. McGowan

    1997-08-01

    Level schemes for the neutron-rich 140,143Ba nuclei have been determined by study of prompt γ-rays in spontaneous fission of 252Cf. The level pattern and enhanced E1 transitions between π = + and π = - bands show reflection asymmetric shapes with simplex quantum number s = +1 in 140Ba and s = ±i in 143Ba, respectively. The octupole deformation stability with spin variation has been discussed.

  2. Ba{sub 2}TeO: A new layered oxytelluride

    SciTech Connect

    Besara, T.; Ramirez, D.; Sun, J.; Whalen, J.B.; Tokumoto, T.D.; McGill, S.A.; Singh, D.J.; Siegrist, T.

    2015-02-15

    Single crystals of the new semiconducting oxytelluride phase, Ba{sub 2}TeO, were synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba{sub 2}TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. The optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba{sub 2}TeO is highly insulating. - Graphical abstract: Starting from a simple stacking of rocksalt layers, the final structure of Ba{sub 2}TeO can be obtained by accommodation of structural strain via atom displacements. Density of states calculations and optical absorbance measurements show that Ba{sub 2}TeO has a band gap of 2.93 eV, indicative of semiconductor behavior. - Highlights: • Single crystal synthesis of a new layered oxytelluride, Ba{sub 2}TeO. • The structure features inverse PbO-type BaO layers and NaCl-type BaTe layers. • Optical absorbance show Ba{sub 2}TeO to be a semiconductor with a 2.93 eV gap. • Density of states indicate a small hybridization between Te 5p and Ba 5d states. • The BaTe (BaO) layers dominate the heat capacity at low (high) temperatures.

  3. Oxygen and cation ordered perovskite, Ba 2Y 2Mn 4O 11

    NASA Astrophysics Data System (ADS)

    Karppinen, M.; Okamoto, H.; Fjellvåg, H.; Motohashi, T.; Yamauchi, H.

    2004-06-01

    A three-step route has been developed for the synthesis of a new oxygen-ordered double perovskite, BaYMn 2O 5.5 or Ba 2Y 2Mn 4O 11. (i) The A-site cation ordered perovskite, BaYMn 2O 5+ δ, is first synthesized at δ≈0 by an oxygen-getter-controlled low-O 2-pressure encapsulation technique utilizing FeO as the getter for excess oxygen. (ii) The as-synthesized, oxygen-deficient BaYMn 2O 5.0 phase is then readily oxygenated to the δ≈1 level by means of 1-atm-O 2 annealing at low temperatures. (iii) By annealing this fully oxygenated BaYMn 2O 6.0 in flowing N 2 gas at moderate temperatures the new intermediate oxygen content oxide, BaYMn 2O 5.5 or Ba 2Y 2Mn 4O 11, is finally obtained. From thermogravimetric observation it is seen that the final oxygen depletion from δ≈1.0 to 0.5 occurs in a single sharp step about 600°C, implying that the oxygen stoichiometry of BaYMn 2O 5+ δ is not continuously tunable within 0.5< δ<1.0. For BaYMn 2O 5.5 synchrotron X-ray diffraction analysis reveals an orthorhombic crystal lattice and a long-range ordering of the excess oxygen atoms in the YO 0.5 layer. The magnetic behavior of BaYMn 2O 5.5 (with a ferromagnetic transition at ˜133 K) is found different from those previously reported for the known phases, BaYMn 2O 5.0 and BaYMn 2O 6.0.

  4. Piezoelectric and Dielectric Properties of Multilayered BaTiO3/(Ba,Ca)TiO3/CaTiO3 Thin Films.

    PubMed

    Zhu, Xiao Na; Gao, Ting Ting; Xu, Xing; Liang, Wei Zheng; Lin, Yuan; Chen, Chonglin; Chen, Xiang Ming

    2016-08-31

    Highly oriented multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films were fabricated on Nb-doped (001) SrTiO3 (Nb:STO) substrates by pulsed laser deposition. The configurations of multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films are designed with the thickness ratio of 1:1:1 and 2:1:1 and total thickness ∼300 nm. Microstructural characterization by X-ray diffraction indicates that the as-deposited thin films are highly c-axis oriented and large in-plane strain is determined in BaTiO3 and CaTiO3 layers. Piezoresponse force microscopy (PFM) studies reveal an intense in-plane polarization component, whereas the out-of-plane shows inferior phase contrast. The optimized combination is found to be the BaTiO3-(Ba0.85Ca0.15)TiO3-CaTiO3 structure with combination ratio 2:1:1, which displays the largest domain switching amplitude under DC electric field, the largest room-temperature dielectric constant ∼646, a small dielectric loss of 0.03, and the largest dielectric tunability of ∼50% at 400 kV/cm. These results suggest that the enhanced dielectric and tunability performance are greatly associated with the large in-plane polarization component and domain switching.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    Ruddlesden-Popper Ba3Zr2O7 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 Ba3Zr2O7 phase from BaZrO3 target. In order to see the post-annealing effects on the structural and optical properties, the deposited Ba3Zr2O7 thin films were annealed at 500, 600 and 800 °C. X-ray diffraction (XRD) reveals the formation of Ba3Zr2O7 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 Ba3Zr2O7 Ruddlesden-Popper-type perovskite structure.

  6. Piezoelectric and Dielectric Properties of Multilayered BaTiO3/(Ba,Ca)TiO3/CaTiO3 Thin Films.

    PubMed

    Zhu, Xiao Na; Gao, Ting Ting; Xu, Xing; Liang, Wei Zheng; Lin, Yuan; Chen, Chonglin; Chen, Xiang Ming

    2016-08-31

    Highly oriented multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films were fabricated on Nb-doped (001) SrTiO3 (Nb:STO) substrates by pulsed laser deposition. The configurations of multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films are designed with the thickness ratio of 1:1:1 and 2:1:1 and total thickness ∼300 nm. Microstructural characterization by X-ray diffraction indicates that the as-deposited thin films are highly c-axis oriented and large in-plane strain is determined in BaTiO3 and CaTiO3 layers. Piezoresponse force microscopy (PFM) studies reveal an intense in-plane polarization component, whereas the out-of-plane shows inferior phase contrast. The optimized combination is found to be the BaTiO3-(Ba0.85Ca0.15)TiO3-CaTiO3 structure with combination ratio 2:1:1, which displays the largest domain switching amplitude under DC electric field, the largest room-temperature dielectric constant ∼646, a small dielectric loss of 0.03, and the largest dielectric tunability of ∼50% at 400 kV/cm. These results suggest that the enhanced dielectric and tunability performance are greatly associated with the large in-plane polarization component and domain switching. PMID:27514235

  7. [Study on continued degradation of BaP and its metabolites].

    PubMed

    Zang, Shu-yan; Li, Pei-Jun; Zhou, Qi-xing; Wang, Xin; Lin, Gui-feng; Wang, Juan

    2006-12-01

    Two metabolites, cis-BP4, 5-dihydrodiol and cis-BP7, 8-dihydrodiol, were identified by high-performance liquid chromatography (HPLC) during the degradation of BaP by Bacillus-07 (BA-07). The two metabolites were hardly further metabolized for their toxicity to microorganism. To promote degradation of BaP and decrease accumulation of cis-BP4, 5-dihydrodiol and cis-BP7, 8-dihydrodiol, two methods (degradation only by BA-07, degradation by coupling the BA-07 and KMnO4) were compared. In addition, parameters of continued degradation of BaP and the two metabolites were optimized under the experiment conditions. The results showed that (1)the method of coupling the chemical oxidation and biodegradation (BA-07 and KMnO4) was better than only biodegradation (BA-07); (2) residue rate of cis-BP4, 5-dihydrodiol was higher than that of cis-BP7, 8-dihydrodiol when the samples were determined in the same time; (3)the effect of continued degradation was the best when the initial concentration of BaP was 40 microg/mL, pH value of the culture was 7.0, co-metabolic substrates was sodium succinate. Meanwhile, it was put forward that the method of coupling the chemical oxidation and biodegradation was effective on continued degradation of persistent organic contaminants in the environment.

  8. 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

    NASA Astrophysics Data System (ADS)

    Rizzo, F.; Augieri, A.; Angrisani Armenio, A.; Galluzzi, V.; Mancini, A.; Pinto, V.; Rufoloni, A.; Vannozzi, A.; Bianchetti, M.; Kursumovic, A.; MacManus-Driscoll, J. L.; Meledin, A.; Van Tendeloo, G.; Celentano, G.

    2016-06-01

    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.

  9. Synthesis and characterization of barium silicide (BaSi2) nanowire arrays for potential solar applications

    NASA Astrophysics Data System (ADS)

    Pokhrel, Ankit; Samad, Leith; Meng, Fei; Jin, Song

    2015-10-01

    In order to utilize nanostructured materials for potential solar and other energy-harvesting applications, scalable synthetic techniques for these materials must be developed. Herein we use a vapor phase conversion approach to synthesize nanowire (NW) arrays of semiconducting barium silicide (BaSi2) in high yield for the first time for potential solar applications. Dense arrays of silicon NWs obtained by metal-assisted chemical etching were converted to single-crystalline BaSi2 NW arrays by reacting with Ba vapor at about 930 °C. Structural characterization by X-ray diffraction and high-resolution transmission electron microscopy confirm that the converted NWs are single-crystalline BaSi2. The optimal conversion reaction conditions allow the phase-pure synthesis of BaSi2 NWs that maintain the original NW morphology, and tuning the reaction parameters led to a controllable synthesis of BaSi2 films on silicon substrates. The optical bandgap and electrochemical measurements of these BaSi2 NWs reveal a bandgap and carrier concentrations comparable to previously reported values for BaSi2 thin films.In order to utilize nanostructured materials for potential solar and other energy-harvesting applications, scalable synthetic techniques for these materials must be developed. Herein we use a vapor phase conversion approach to synthesize nanowire (NW) arrays of semiconducting barium silicide (BaSi2) in high yield for the first time for potential solar applications. Dense arrays of silicon NWs obtained by metal-assisted chemical etching were converted to single-crystalline BaSi2 NW arrays by reacting with Ba vapor at about 930 °C. Structural characterization by X-ray diffraction and high-resolution transmission electron microscopy confirm that the converted NWs are single-crystalline BaSi2. The optimal conversion reaction conditions allow the phase-pure synthesis of BaSi2 NWs that maintain the original NW morphology, and tuning the reaction parameters led to a controllable

  10. Synthesis and Photoluminescent Properties of Eu²⁺-Doped BaSiF₆ Nanoparticles.

    PubMed

    Zhao, Xin; Hua, Ruinian; Zhang, Wei; Zhao, Jun; Tang, Dongxin; Sun, Zhengang

    2016-01-01

    By adjusting the molar ratio of oleic acid (OA), oleylamine (OM), and 1-octadecene (OD) ligands in reaction solution, Eu²⁺-doped BaSiF₆ nanoparticles were synthesized using a thermal decomposition synthesis route. Eu²⁺ ions have been successfully doped into BaSiF₆ host lattice and strong 4f-4f line emission of the Eu²⁺ in BaSiF₆ matrix is observed. Meanwhile, the photoluminescent (PL) properties of BaSiF₆:Eu²⁺ nanoparticles doping Eu²⁺ ions at different concentrations were also studied. PMID:27398531

  11. Method of forming superconducting Tl-Ba-Ca-Cu-O films

    DOEpatents

    Wessels, Bruce W.; Marks, Tobin J.; Richeson, Darrin S.; Tonge, Lauren M.; Zhang, Jiming

    1993-01-01

    A method of forming a superconducting Tl-Ba-Ca-Cu-O film is disclosed, which comprises depositing a Ba-Ca-Cu-O film on a substrate by MOCVD, annealing the deposited film and heat-treating the annealed film in a closed circular vessel with TlBa.sub.2 Ca.sub.2 Cu.sub.3 O.sub.x and cooling to form said superconducting film of TlO.sub.m Ba.sub.2 Ca.sub.n-1 Cu.sub.n O.sub.2n+2, wherein m=1,2 and n=1,2,3.

  12. Induced antiferromagnetism in Mn doped BaMgF{sub 4}

    SciTech Connect

    Manikandan, M. Muthukumaran, A. Venkateswaran, C.

    2014-04-24

    Pure and Mn doped BaMgF{sub 4} samples have been synthesized by the hydrothermal method. X-ray diffraction (XRD) pattern of both the samples reveal the formation of pure BaMgF{sub 4} phase. High resolution scanning electron micrographs (HRSEM) show rectangular shape particles. At room temperature, the undoped BaMgF{sub 4} shows diamagnetic behavior where as the 5% Mn doped BaMgF{sub 4} exhibits antiferromagnetic hysteresis loop. The possible reason for room temperature antiferromagnetism and the role of dopant ion have been investigated.

  13. Controlled confinement of half-metallic two-dimensional electron gas in BaTiO3/Ba2FeReO6 /BaTiO3 heterostructures: A first-principles study

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    Using density functional theory calculations, we establish that the half-metallicity of bulk Ba2FeReO6 survives down 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 ultrathin spintronic devices.

  14. On Ba(+) production in the CRIT 2 experiment

    NASA Technical Reports Server (NTRS)

    Liou, K.; Torbert, R. B.

    1995-01-01

    Analysis of partical data from the CRIT 2 experiment, studying Alfven's critical ionization velocity (CIV) effect, shows that the density of newly created ions (presumably Ba(+) from the shaped-charge beam) is consistent with the increase in total plasma density measured by the independent RF plasma probe on board (Swenson et al., 1990) at the most active time period. We model this ion production using the measured electron flux data and the neutral barium model of Stenbaek-Nielsen et al. (1990a). To identify the main source mechanisms which may contribute most to the barium ionization, a simple model for the barium ion density at the payload location is developed based on Liouvilles theorem. We estimate that the electron impact ionization is responsible for 90% of the barium ion production observed by CRIT 2 in the first release and up to 45% in the second release. By employing a two-state approximation calculation (Rapp and Francis, 1962), the Ba-O(+) charge exchange cross section is found to range from about 2.0 X 10(exp -17) sq cm at a velocity of 4 km/s to 2.0 X 10(exp -15) sq cm at a velocity of 20 km/s. This result suggests that the Ba-O(+) charge exchange is probably dominant among all the non-CIV ionization processes. By considering the charge exchange process in our density model, the barrium ion densities are calculated for the two releases on CRIT II. The comparison between the model results and the observed data is found to be resonably consistent if the cross sections, as calculated above, are multiplied by 0.3 for the first release and 1.0 for the second release. Our result suggests that the charge exchange process could be the most important non-CIV ionization mechanism in the CRIT II experiment and it should be considered carefully case by case in CIV experiments.

  15. On Ba(+) production in the CRIT 2 experiment

    NASA Astrophysics Data System (ADS)

    Liou, K.; Torbert, R. B.

    1995-04-01

    Analysis of partical data from the CRIT 2 experiment, studying Alfven's critical ionization velocity (CIV) effect, shows that the density of newly created ions (presumably Ba(+) from the shaped-charge beam) is consistent with the increase in total plasma density measured by the independent RF plasma probe on board (Swenson et al., 1990) at the most active time period. We model this ion production using the measured electron flux data and the neutral barium model of Stenbaek-Nielsen et al. (1990a). To identify the main source mechanisms which may contribute most to the barium ionization, a simple model for the barium ion density at the payload location is developed based on Liouvilles theorem. We estimate that the electron impact ionization is responsible for 90% of the barium ion production observed by CRIT 2 in the first release and up to 45% in the second release. By employing a two-state approximation calculation (Rapp and Francis, 1962), the Ba-O(+) charge exchange cross section is found to range from about 2.0 X 10(exp -17) sq cm at a velocity of 4 km/s to 2.0 X 10(exp -15) sq cm at a velocity of 20 km/s. This result suggests that the Ba-O(+) charge exchange is probably dominant among all the non-CIV ionization processes. By considering the charge exchange process in our density model, the barrium ion densities are calculated for the two releases on CRIT II. The comparison between the model results and the observed data is found to be resonably consistent if the cross sections, as calculated above, are multiplied by 0.3 for the first release and 1.0 for the second release. Our result suggests that the charge exchange process could be the most important non-CIV ionization mechanism in the CRIT II experiment and it should be considered carefully case by case in CIV experiments.

  16. Thermodynamics of phosphorus and sulfur in the BaO-MnO flux system between 1573 and 1673 K

    NASA Astrophysics Data System (ADS)

    Watanabe, Yoshinori; Kitamura, Katsuhiro; Rachev, Ivan Petkov; Tsukihashi, Fumitaka; Sano, Nobuo

    1993-04-01

    The oxidative dephosphorization of carbon-saturated Fe-Mn alloys was successfully demonstrated by measuring the phosphorus partition ratio between BaO-MnO, BaO-MnO-BaF2, and BaO-CaOsatd.-MnO fluxes and liquid Fe-Mn-Csatd. alloy between 1573 and 1673 K. The phosphorus partition ratio increases with increasing BaO content of the flux. The phosphate capacity of the BaO-MnO flux is as high as that of the BaO-BaF2 flux and is far larger than those of CaO-bearing fluxes. Addition of BaF2 to the BaO-MnO flux increases BaO solubility, which increases the phosphate capacity. The manganese partition ratios between the BaO-MnO flux and Fe-Mn-Csatd. alloy were approximately constant at 0.64, 0.33, and 0.23 at 1573, 1623, and 1673 K, respectively. The carbon content of the BaO-MnO flux was measured as functions of slag composition, temperature, and partial pressure of CO. A stable species of carbon in the BaO-MnO flux was found to be BaC2 experimentally and thermodynamically. The sulfide capacity of the BaO-MnO system at 1573 K has been shown to be far larger than any known flux systems and to be a few times larger than that for the BaO-BaF2 system.

  17. Charm and Charmonium Spectroscopy at BaBar

    SciTech Connect

    Palano, Antimo; /Bari U. /INFN, Bari

    2011-11-22

    In the last few years many new unexpected new particles have been discovered in the analysis of B-factories data. In the charm sector, the newly discovered D{sub s} mesons are difficult to explain within potential models. In the charmonium sector, the large variety of new states are difficult to accommodate in the quark model and some of them are candidates for being hybrids or 4-quark states. Results will be presented on charm and charmonium spectroscopy from BaBar experiment using inclusive e{sup +}e{sup -} interactions, B decays and exclusive ISR reactions.

  18. EBSD analysis of the microtexture of Ba-hexaferrite samples

    NASA Astrophysics Data System (ADS)

    Koblischka-Veneva, A.; Koblischka, M. R.; Schmauch, J.; Chen, Y.; Harris, V. G.

    2010-01-01

    The microtexture of differently prepared Ba-hexaferrite samples is investigated by means of electron backscatter diffraction (EBSD). Kikuchi patterns are obtained with a high image quality, enabling a spatial resolution of the EBSD maps of about 20 nm. The spatially highly resolved EBSD mappings provide additional information (individual grain orientation, misorientation angles, grain size distribution) as compared to the standard analysis techniques, which can contribute to an optimization of the growth process. Furthermore, as the crystallographic orientation of each grain is known, an exact analysis of the grain aspect ratio becomes possible which provides further insight to the microstructural dependence of the magnetic properties of ferrites.

  19. Photogrammetry measurement of the AMiBA 6-meter platform

    NASA Astrophysics Data System (ADS)

    Huang, Yau De; Raffin, Philippe; Chen, Ming-Tang; Altamirano, Pablo; Oshiro, Peter

    2008-07-01

    This paper describes the photogrammetry method as a mean to measure the deformation of the 6-meter carbon fiber reinforced plastic (CFRP) Platform of the AMiBA interferometric array telescope installed at the Mauna Loa Observatory, Hawaii. The Platform was surveyed at a series of elevation, azimuth and polarization angles. Photogrammetry demonstrates that the deformation of the Platform is not only gravity-induced but also due to the Hexapod mount actuator. The measurement results verify the predictions of the Finite Element Analysis (FEA).

  20. The Yuan Tseh Lee AMiBA Project

    NASA Astrophysics Data System (ADS)

    Ho, Paul T. P.; Altimirano, Pablo; Birkinshaw, Mark; Chang, Su-Wei; Chang, Cha-Hao; Chen, Ke-Jun; Chen, Mingtang; Chiueh, Tzi-Dar; Chiueh, Tzihong; Chu, Tah-Hsiung; Han, Chih-Chiang; Huang, Chi-Wei; Huang, Yao-De; Hwang, W.-Y. Pauchy; Hwang, Yuh-Jing; Jiang, Homin; Kesteven, Michael; Koch, Patrick; Kubo, Derek; Lancaster, Katy; Li, Chao-Te; Liang, Haida; Liao, Yao-Wei; Lim, Jeremy; Lin, Yen-Shen; Lin, Kai-Yang; Liu, Guo-Chin; Lo, Kwok-Yung; Ma, Cheng-Jiun; Martin-Cocher, Pierre; Martin, Robert N.; Molnar, Sandor; Ng, Kin-Wang; Nishioka, Hiroaki; Park, Chan-Gyung; Patt, Ferdinand; Peterson, Jeffrey B.; Raffin, Philippe; Romano, Fabi; Wang, Huei; Umetsu, Keiichi; Wang, Fu-Cheng; Wu, Jiun-Huei Proty

    The Array for Microwave Background Anisotropy is a 7-element interferometer sited on Mauna Loa, Hawaii. The seven 60cm telescopes are mounted on a 6-meter platform, and operates at 3mm wavelength. In October 2006, the telescope was officially dedicated and renamed as the Y. T. Lee AMiBA. During 2007, scientific operations have begun, after a long process of calibration and testing. At the time of this meeting, six clusters of galaxies have been detected and mapped via the inverse Compton scattering of the Cosmic Microwave Background radiation, also known as the Sunyaev-Zel'dovich Effect.

  1. Selected Topics on Hadronic B Decays From BaBar

    SciTech Connect

    Suzuki, K.; /SLAC

    2011-11-23

    Recent measurements of branching fractions and decay-rate asymmetries in charmless hadronic B decays at the BaBar experiment are presented. The selected topics include Dalitz plot analyses of B {yields} K{sup +} {pi}{sup -}{pi} and signal searches in B {yields} PP and PV, where isoscalar mesons are involved, and in B {yields} b{sub 1}P, P and V denote a pseudoscalar and vector meson, respectively. Several measurements in charmless hadronic B decays have indicated possible deviations from the theoretical predictions within the Standard Model. The measurements presented would contribute to searching for and resolving such puzzles.

  2. Ca/Ba/Sr-induced conformational changes of ciliary axonemes.

    PubMed

    Tamm, S; Tamm, S

    1990-01-01

    Macrocilia of the ctenophore Beroë undergo Ca/Ba/Sr-dependent activation of ciliary beating and microtubule sliding disintegration [Tamm, J. Comp. Physiol. A163:23-31, 1988a; Tamm, Cell Motil. Cytoskeleton 11:126-138, 1988b; Tamm, Cell Motil. Cytoskeleton 12:104-112, 1989; Tamm and Tamm, Proc. Natl. Acad. Sci. U.S.A. 86:6987-6991, 1989]. Here we report that detergent-extracted macrocilia show an ATP-independent conformational change in response to high concentrations of Ca, Ba, or Sr ions. When applied locally by iontophoresis, these ions induce a rapid planar curvature of the distal end of the macrociliary shaft, followed by a slower relaxation to the rest position. Tip curling occurs in a direction opposite to the physiological Ca/Ba/Sr response. When applied uniformly in the bath, a threshold concentration of 10(-1) M Sr is required to induce curling of the tip, and the distal ends remain curved. Calmodulin antagonists do not inhibit the tip curling response. Previous workers found that Ca induces changes in the helical shape of isolated doublet microtubules [Miki-Noumura and Kamiya, Exp. Cell Res. 97:451-453, 1976; Miki-Noumura and Kamiya, J. Cell Biol. 81:355-360, 1979; Takasaki and Miki-Noumura, J. Mol. Biol. 158:317-324, 1982] and sperm axonemes [Okuno and Brokaw, Cell Motil. 1:349-362, 1981] and suggested that conformational changes in microtubules may play a role in Ca regulation of ciliary motility. We propose that the Ca/Ba/Sr-induced curling of the macrociliary tip is due to similar helical changes of doublet microtubules, some of which in macrocilia are prevented from sliding by permanent connections (compartmenting lamellae) between adjacent axonemes within the shaft. Although the tip curling response does not appear to be directly relevant to the physiological Ca response of macrocilia, it provides a novel system for investigating Ca-induced conformational changes of microtubules independent of dynein-powered active sliding.

  3. Dynamic nonlinearity in epitaxial BaTi O3 films

    NASA Astrophysics Data System (ADS)

    Tyunina, M.; Savinov, M.

    2016-08-01

    Dynamic dielectric and piezoelectric constants of ferroelectrics increase proportionally to the amplitude of alternating electric field as a result of hysteretic Rayleigh-type motion of domain walls. Here a hysteresis-free quadratic field dependence of the dynamic dielectric response is experimentally demonstrated in the absence of domain walls in epitaxial BaTi O3 films. This extraordinary behavior is related to polar entities, whose presence is confirmed by the Vogel-Fulcher relaxation. The polar entities are ascribed to polarization fluctuations associated with lattice inhomogeneity.

  4. BaCdSnS4 and Ba3CdSn2S8: syntheses, structures, and non-linear optical and photoluminescence properties.

    PubMed

    Zhen, Ni; Wu, Kui; Wang, Ying; Li, Qiang; Gao, Wenhui; Hou, Dianwei; Yang, Zhihua; Jiang, Huaidong; Dong, Yongjun; Pan, Shilie

    2016-06-28

    Two non-centrosymmetric metal chalcogenides, BaCdSnS4 and Ba3CdSn2S8, were synthesized using a high temperature solid-state reaction in an evacuated silica tube. Although the two compounds have the same building units in their structures, namely CdS4, SnS4 and BaS8 units, both of them have different structures. BaCdSnS4 crystallizes in the orthorhombic space group Fdd2 and its structure can be characterized by the two-dimensional ∞[Cd-Sn-S] layers composed of corner- and edge-sharing CdS4 and SnS4 tetrahedra with Ba atoms located between the two adjacent ∞[Cd-Sn-S] layers. Ba3CdSn2S8 crystallizes in the space group I4[combining macron]3d of the orthorhombic system and the CdS4 and SnS4 groups are connected with each other via corner-sharing to form a three-dimensional framework, which is different from the 2D ∞[Cd-Sn-S] layer structure in BaCdSnS4. The UV-vis-NIR diffuse-reflectance spectra show that the experimental band gaps are about 2.30 eV for BaCdSnS4 and 2.75 eV for Ba3CdSn2S8, respectively. IR and Raman measurement results indicate that their transparent ranges are up to 25 μm. Second-order NLO measurements show that BaCdSnS4 exhibits strong powder second-harmonic generation (SHG) intensities at 2.09 μm laser pumping that are ∼5 and 0.7 times that of AgGaS2 in the particle size 38-55 and 150-200 μm, respectively, whereas Ba3CdSn2S8 only exhibits SHG intensities of about 0.8 and 0.1 times that of AgGaS2 at the same particle sizes. The origin of the NLO response in BaCdSnS4 may originate from the macroscopic arrangement of the SnS4 and CdS4 tetrahedra. Furthermore, the photoluminescence properties of the two compounds have also been investigated and show obvious blue and green light emission. PMID:27272926

  5. Improved synthesis of ceramic superconductors with alkaline earth peroxides - Synthesis and processing of Ba2YCu3O(7-x)

    NASA Technical Reports Server (NTRS)

    Hepp, A. F.; Gaier, J. R.; Philipp, W. H.; Warner, J. D.; Aron, P. R.; Pouch, J. J.

    1988-01-01

    Synthesis processes for the preparation of ceramic conductors Ba2YCu3O(7-x) from BaO2 or BaCO3 in flowing O2 or N2 are described, and the characteristics of the materials produced in these processes are compared. Results of EDAX, XRD, SEM, and dc resistivity analyses demonstrated that superconducting materials made from BaO2 were more homogeneous, denser, and more metallic than materials produced from BaCO3, because of the higher reactivity of BaO2. Potential applications of this processes are discussed.

  6. NOx Uptake Mechanism on Pt/BaO/Al2O3 Catalysts

    SciTech Connect

    Kwak, Ja Hun; Kim, Do Heui; Szailer, Tamas; Peden, Charles HF; Szanyi, Janos

    2006-11-01

    The NOx adsorption mechanism on Pt/BaO/Al2O3 catalysts was investigated by performing NOx storage/reduction cycles, NO2 adsorption and NO + O2 adsorption on 2%Pt/(x)BaO/Al2O3 (x = 2, 8 and 20 wt%) catalysts. NOx uptake profiles on 2%Pt/20%BaO/Al2O3 at 523 K show complete uptake behavior for almost 5 min, and then the NOx level starts gradually increasing with time and it reaches 75% of the inlet NOx concentration after 30 min time-on-stream. Although this catalyst shows fairly high NOx conversion at 523 K, only ~ 2.4 wt% out of 20 wt% BaO is converted to Ba(NO3)2. Adsorption studies by using NO2 and NO + O2 suggest two different NOx adsorption mechanisms. The NO2 uptake profile on 2%Pt/20%BaO/Al2O3 shows the absence of a complete NOx uptake period at the beginning of adsorption and the overall NOx uptake is controlled by the gas-solid equilibrium between NO2 and BaO/Ba(NO3)2 phase. When we use NO + O2, complete initial NOx uptake occurs and the time it takes to convert ~ 4 % of BaO to Ba(NO3)2 is independent of the NO concentration. These NOx uptake characteristics suggest that the NO + O2 reaction on the surface of Pt particles produces NO2 that is subsequently transferred to the neighboring BaO phase by spill over. At the beginning of the NOx uptake, this spill-over process is very fast and so it is able to provide complete NOx storage. However, the NOx uptake by this mechanism slows down as BaO in the vicinity of Pt particles are converted to Ba(NO3)2. The formation of Ba(NO3)2 around the Pt particles results in the development of a diffusion barrier for NO2, and increases the probability of NO2 desorption and consequently, the beginning of NOx slip. As NOx uptake by NO2 spill-over mechanism slows down due to the diffusion barrier formation, the rate and extent of NO2 uptake are determined by the diffusion rate of nitrate ions into the BaO bulk, which, in turn, is determined by the gas phase NO2 concentration.

  7. Barium Qubit State Detection and Ba Ion-Photon Entanglement

    NASA Astrophysics Data System (ADS)

    Sosnova, Ksenia; Inlek, Ismail Volkan; Crocker, Clayton; Lichtman, Martin; Monroe, Christopher

    2016-05-01

    A modular ion-trap network is a promising framework for scalable quantum-computational devices. In this architecture, different ion-trap modules are connected via photonic buses while within one module ions interact locally via phonons. To eliminate cross-talk between photonic-link qubits and memory qubits, we use different atomic species for quantum information storage (171 Yb+) and intermodular communication (138 Ba+). Conventional deterministic Zeeman-qubit state detection schemes require additional stabilized narrow-linewidth lasers. Instead, we perform fast probabilistic state detection utilizing efficient detectors and high-NA lenses to detect emitted photons from circularly polarized 493 nm laser excitation. Our method is not susceptible to intensity and frequency noise, and we show single-shot detection efficiency of ~ 2%, meaning that we can discriminate between the two qubits states with 99% confidence after as little as 50 ms of averaging. Using this measurement technique, we report entanglement between a single 138 Ba+ ion and its emitted photon with 86% fidelity. This work is supported by the ARO with funding from the IARPA MQCO program, the DARPA Quiness program, the AFOSR MURI on Quantum Transduction, and the ARL Center for Distributed Quantum Information.

  8. Energy levels, lifetimes and radiative data of Ba XXVI

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Goyal, Arun; Khatri, Indu; Aggarwal, Sunny; Sharma, Rinku; Mohan, Man

    2016-05-01

    We report an extensive and an elaborate theoretical study of atomic data for Ba XXVI by considering Singlet, Doublet and Triplet (SDT) electron excitations within N-shell and single excitations from N-shell to O-shell. We have calculated energy levels and lifetimes for lowest 110 fine structure levels by using Multi-configuration Dirac-Fock method (MCDF). We have also considered Quantum Electrodynamics (QED) and Breit corrections in our calculations. We have presented the radiative data for electric and magnetic dipole (E1, M1) and quadrupole (E2, M2) transitions among lowest 110 levels. We have made comparisons of our calculated excitation energies and EUV (Extreme Ultraviolet) transition wavelengths with experimentally observed energy levels and wavelengths and achieved good agreement. We have also computed energy levels by performing similar relativistic distorted wave calculations using Flexible Atomic Code (FAC). Additionally, we have provided new atomic data for Ba XXVI which are not published elsewhere in the literature. We believe that our results may be beneficial in fusion plasma research and astrophysical investigations and applications.

  9. Towards a sub 15-dBA optical micromachined microphone

    PubMed Central

    Kim, Donghwan; Hall, Neal A.

    2014-01-01

    Micromachined microphones with grating-based optical-interferometric readout have been demonstrated previously. These microphones are similar in construction to bottom-inlet capacitive microelectromechanical-system (MEMS) microphones, with the exception that optoelectronic emitters and detectors are placed inside the microphone's front or back cavity. A potential advantage of optical microphones in designing for low noise level is the use of highly-perforated microphone backplates to enable low-damping and low thermal-mechanical noise levels. This work presents an experimental study of a microphone diaphragm and backplate designed for optical readout and low thermal-mechanical noise. The backplate is 1 mm × 1 mm and is fabricated in a 2-μm-thick epitaxial silicon layer of a silicon-on-insulator wafer and contains a diffraction grating with 4-μm pitch etched at the center. The presented system has a measured thermal-mechanical noise level equal to 22.6 dBA. Through measurement of the electrostatic frequency response and measured noise spectra, a device model for the microphone system is verified. The model is in-turn used to identify design paths towards MEMS microphones with sub 15-dBA noise floors. PMID:24815250

  10. Redetermination of β-Ba(PO3)2.

    PubMed

    Weil, Matthias

    2014-02-01

    In comparison with the previous structure determination of the β-modification of barium catena-polyphosphate that was based on Weissenberg film data [Grenier et al. (1967 ▶). Bull. Soc. Fr. Minéral. Cristallogr. 90, 24-31], the current CCD-data-based redetermination reveals all atoms with anisotropic displacement parameters, standard uncertainties for the atomic coordinates, and the determination of the absolute structure. Moreover, a much higher accuracy in terms of the bond-length distribution for the polyphosphate chain, with two shorter and two longer P-O distances, was achieved. The structure consists of polyphosphate chains extending parallel to [100] with a periodicity of two PO4 tetra-hedra. The Ba(2+) cations are located between the chains and are surrounded by ten O atoms in the form of a distorted coordination polyhedron, with Ba-O distances ranging from 2.765 (3) to 3.143 (3) Å, also reflecting the higher precision of the current redetermination.

  11. Multi-colony calibrations of coral Ba/Ca with a contemporaneous in situ seawater barium record

    NASA Astrophysics Data System (ADS)

    LaVigne, Michèle; Grottoli, Andréa G.; Palardy, James E.; Sherrell, Robert M.

    2016-04-01

    The coral skeleton barium to calcium ratio (Ba/Cacoral), a proxy for seawater barium concentrations (BaSW), has been interpreted as a tracer of upwelling based on the characteristic "nutrient like" depth profile of BaSW. However, in some tropical regions, such as the Gulf of Panamá, substantial influence of terrestrial runoff inputs and differences between the vertical distribution of BaSW and that of the major nutrients (nitrate and phosphate) in the upper water column can complicate the interpretation of Ba/Cacoral as an upwelled nutrient proxy. In the Gulf of Panamá, contemporaneous Ba/Cacoral records from multiple colonies of Porites lobata, Pavona gigantea, and Pavona clavus corals record a nearly twofold change in surface water BaSW as a 20-70% increase in skeletal Ba/Ca with excellent correlation among Ba/Ca records from co-located colonies (r = 0.86-0.99). These results provide, for the first time, an absolute calibration of the coral Ba proxy with a contemporaneous BaSW record. Compiling the Ba/Cacoral records from three co-located colonies of each species into taxon-specific composite regressions reveals strong statistically significant correlations with the BaSW time-series record (p < 0.001). Differences among taxa in regression slope, y-intercept, and average distribution coefficient, as well as a demonstration of the application of the P. clavus calibration to a previously published Ba/Cacoral record, emphasize the necessity of using taxon-specific calibrations to reconstruct changes in BaSW with accuracy. These results support the application of Ba/Cacoral to reconstruct past changes in absolute BaSW concentrations, adding an important tool to the collection of geochemical proxies for reconstructing surface ocean biogeochemical processes in the past.

  12. Characterization of novel BaZnSnO thin films by solution process and applications in thin film transistors

    SciTech Connect

    Li, Jun; Huang, Chuan-Xin; Zhang, Jian-Hua; Zhu, Wen-Qing; Jiang, Xue-Yin; Zhang, Zhi-Lin

    2015-08-15

    Graphical abstract: This work reports the Ba content on thin film transistor based on a novel BaZnSnO semiconductor using solution process. - Highlights: • No reports about BaZnSnO thin film using solution process. • BaZnSnO thin film transistor (TFT) was firstly fabricated. • BaZnSnO-TFT shows a acceptable performace. • Influence of Ba content on BaZnSnO-TFT. - Abstract: A novel BaZnSnO semiconductor is fabricated using solution process and the influence of Ba addition on the structure, the chemical state of oxygen and electrical performance of BaZnSnO thin films are investigated. A high performance BaZnSnO-based thin film transistor with 15 mol% Ba is obtained, showing a saturation mobility of 1.94 cm{sup 2}/V s, a threshold voltage of 3.6 V, an on/off current ratio of 6.2 × 10{sup 6}, a subthreshold swing of 0.94 V/decade, and a good bias stability. Transistors with solution processed BaZnSnO films are promising candidates for the development of future large-area, low-cost and high-performance electronic devices.

  13. Evidence for extinct 135Cs from Ba isotopes in Allende CAIs?

    NASA Astrophysics Data System (ADS)

    Bermingham, K. R.; Mezger, K.; Desch, S. J.; Scherer, E. E.; Horstmann, M.

    2014-05-01

    The abundance and distribution of isotopes throughout the Solar System can be used to constrain the number and type of nucleosynthetic events that contributed material to the early nebula. Barium is particularly well suited to quantifying the degree of isotope heterogeneity in the Solar System because it comprises seven stable isotopes that were synthesized by three different nucleosynthetic processes (s-, r-, and p-processes), all of which contributed material to the Solar System. There is also potential contribution to 135Ba from short-lived radioisotope 135Cs, conclusive evidence for which is yet to be reported. Four Allende (CV3) Ca,Al-rich inclusions (CAI 1, CAI 2, CAI 4, CAI 5) and one Allende dark inclusion (DI) were analyzed for Ba isotope variability. Two CAIs (CAI 2 and CAI 5) display 135Ba excesses that are not accompanied by 137Ba anomalies. Calcium-aluminum-rich inclusion 1 displays a 135Ba excess that is possibly coupled with a 137Ba excess, and the remaining refractory inclusions (CAI 2 and DI) have terrestrial Ba isotope compositions. These Ba isotope data are presented in conjunction with published whole rock Ba isotope data from individual Allende CAIs. The enrichment in 135Ba and absence of coupled 137Ba excesses in CAI 2 and CAI 5 is interpreted to indicate that the anomalies are not purely nucleosynthetic in origin but also contain contributions (16-48 ppm) from the decay of short-lived 135Cs. The majority of Allende CAIs studied to date may also have similar contributions from 135Cs on the basis of higher than expected 135Ba excesses if the Ba isotope anomalies were purely nucleosynthetic in origin. The 135Ba anomalies appear not to be coupled with superchondritic Cs/Ba, which may imply that the contribution to 135Ba did not occur via in situ decay of live 135Cs. However, it is feasible that the CAIs had a superchondritic Cs/Ba during decay of 135Cs, but Cs was subsequently removed from the system during aqueous alteration on the parent body

  14. Microstructures and properties of superconducting Y-ErBaCuO thin films obtained from disordered Y-ErBaF2Cu films

    NASA Technical Reports Server (NTRS)

    Cikmach, P.; Diociaiuti, M.; Fontana, A.; Giovannella, C.; Iannuzzi, M.; Lucchini, C.; Merlo, V.; Messi, R.; Paoluzi, L.; Scopa, L.

    1991-01-01

    The preparation procedure used to obtain superconducting thin films by radio frequency magnetron sputtering of a single mosaic target is described in detail. The single mosaic target is composed of (Y-Er), BaF2, and Cu.

  15. Electron-impact ionization of laser-excited Ba-138 (... 5p6 6s 6p) and Ba-138 (... 5p6 6s 5d) atoms

    NASA Technical Reports Server (NTRS)

    Trajmar, S.; Nickel, J. C.; Antoni, T.

    1986-01-01

    Electron-impact ionization cross sections for laser-excited Ba-138 (... 5p6 6s 6p; 1P1, M = - 1) and cascade-populated Ba-138 (... 5p6 6s 5d; 1D + 3D) atoms were measured in the threshold to 10 eV energy range. The peak cross sections for the excited species are about a factor of 2 larger than that for ground-state Ba. In addition, it was demonstrated that ionization from individual magnetic substates of various hyperfine levels can be studied. The ionization cross sections in the case of Ba-138 (1P1) were found to be equal for the M = 0 and for the M = + or - 1 sublevels within the experimental error limit.

  16. Synthesis, crystal and electronic structures of the new Zintl phases Ba3Al3Pn5 (Pn = P, As) and Ba3Ga3P5.

    PubMed

    He, Hua; Tyson, Chauntae; Saito, Maia; Bobev, Svilen

    2013-01-01

    The new Zintl compounds Ba(3)Al(3)P(5), Ba(3)Al(3)As(5,) and Ba(3)Ga(3)P(5) have been synthesized using molten metal fluxes. They are isoelectronic and isotypic, crystallizing with a novel rhombohedral structure type in the space group R3c with unit cell constants a = 14.5886(9) Å, c = 28.990(3) Å for Ba(3)Al(3)P(5), a = 14.613(3) Å, c = 28.884(8) Å for Ba(3)Ga(3)P(5), and a = 14.9727(13) Å, c = 29.689(4) Å for Ba(3)Al(3)As(5), respectively. The structures are based on TrPn(4) (Tr = Al, Ga; Pn = P, As) tetrahedra that share both edges and corners, leading to intricate arrangements embodied in the [Tr(4)Pn(9)](15-) and [Tr(3)Pn(6)](9-) strands, interconnected by dimeric [Tr(2)Pn(6)](12-) units. The Ba(2+) cations reside within cylindrical channels within the polyanionic framework and provide the valence electrons needed for Tr-Pn covalent bonding. In spite of the large and complex structure, there are no homoatomic Tr-Tr or Pn-Pn interactions, hence, the structures can be readily rationalized in the context of the Zintl-Klemm formalism as follows [Ba(2+)](3)[Tr(3+)](3)[Pn(3-)](5); calculations on their electronic band-structures confirm this reasoning and reveal about 1.4-1.9 eV energy band gaps, that is, semiconducting behavior. Structural parallels with other known Zintl compounds are also presented.

  17. Microstructures and properties of superconducting Y-Er-BaCu-O thin films obtained from disordered Y-Er-BaF2-Cu films

    NASA Technical Reports Server (NTRS)

    Cikmach, P.; Diociaiuti, M.; Fontana, A.; Giovannella, C.; Iannuzzi, M.; Lucchini, C.; Messi, R.; Paoluzi, L.; Scopa, L.; Tripodi, P.

    1990-01-01

    Since the first reports on superconducting thin films obtained by evaporating BaF2, Cu and Y(sup 1), or Yb or Er(sup 2), several others have followed. All these reports describe thin films prepared by means of molecular beam cells or electron guns. Researchers show that films with similar properties can be obtained by radio frequency sputtering of a single mosaic target composed by Y-Er, BaF2 and Cu. Process steps are described.

  18. A facile method for the preparation of Eu{sup 2+}-doped nanocrystalline BaFCl

    SciTech Connect

    Wang, Xianglei; Liu, Zhiqiang; Stevens-Kalceff, Marion A.; Riesen, Hans

    2013-10-15

    Graphical abstract: - Highlights: • A facile co-precipitation method for the preparation of Eu{sup 2+}-doped BaFCl. • Reduction of Eu{sup 3+} to Eu{sup 2+} by zinc granular under nitrogen flow. • Photoluminescence and cathodoluminescence spectroscopy of the as-prepared BaFCl:Eu{sup 2+}. • Temperature dependent photoluminescence properties of Eu{sup 2+} ions in BaFCl. - Abstract: A facile method for the preparation of Eu{sup 2+}-doped BaFCl is reported. The method is based on the co-precipitation of aqueous solutions of BaCl{sub 2} and NH{sub 4}F to yield BaFCl. The doping by europium in the 2+ oxidation state is realized by the reduction of Eu{sup 3+} to Eu{sup 2+} employing granular zinc in the BaCl{sub 2} solution under nitrogen. Powder X-ray diffraction and electron microscopy have been used to confirm the BaFCl phase and photoluminescence, in the temperature range of 2.5–290 K, and room-temperature cathodoluminescence spectra have been measured to characterize the Eu{sup 2+} ions in the sample.

  19. The solubility of BaCO3(cr) (witherite) in CO2-H2O solutions between 0 and 90°C, evaluation of the association constants of BaHCO3+(aq) and BaCO30(aq) between 5 and 80°C, and a preliminary evaluation of the thermodynamic properties of Ba2+(aq)

    USGS Publications Warehouse

    Busenberg, Eurybiades; Plummer, L. Niel

    1986-01-01

    Problems in the thennodynamic selections of Ba compounds are considered. Newer data require the revision of ΔfH° and ΔfG° of Ba2+(aq) to −532.5 and −555.36 kJ · mol−1, respectively, for agreement with solubility data.

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

    SciTech Connect

    Hough, J.L.; Darrow, D.; Eaton, J.; Baird, M.B. )

    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. The Acquisition of the BA Construction by English-Speaking Learners of Chinese

    ERIC Educational Resources Information Center

    Xu, Hongying

    2012-01-01

    This study examined the acquisition of the BA construction by English-speaking learners of Chinese. The BA construction is a unique yet important grammar phenomenon in Chinese. Whether second language (L2) learners of Chinese are able to understand and use this construction correctly and appropriately may affect the overall success of their…

  2. PrBa{sub 2}Cu{sub 3}O{sub 7}: A new superconductor

    SciTech Connect

    Blackstead, H.A.; Dow, J.D.

    1995-10-01

    PrBa{sub 2}Cu{sub 3}O{sub 7} superconducts, provided Pr is kept off Ba-sites - experimentally confirming the prediction of the oxygen model and indicating that superconductivity originates in the chains, not in the planes.

  3. Characterization of LiF/CuO-Codoped BaTiO3 for Embedded Capacitors

    NASA Astrophysics Data System (ADS)

    Lee, Kyoungho

    2015-03-01

    Sintering additives for BaTiO3 were studied in order to facilitate the use of BaTiO3 as a material for embedded decoupling capacitors in high-density multilayered low-temperature cofired ceramic (LTCC) modules for mobile communication systems and three-dimensional (3D) printing modules. Among the studied additives, the CuO/LiF mixture was the most promising sintering additive for cofiring BaTiO3 with a commercial low-permittivity ( ɛ r) LTCC sheet (MLS-22, NEG Co.). The temperature dependence of the dielectric properties of BaTiO3 was successfully controlled by adjusting the CuO/LiF amount and ratio and the sintering temperature. BaTiO3 codoped with 10 wt.% LiF/CuO (1:1 ratio) and sintered at 860°C for 30 min showed 95% sintering density. The room-temperature permittivity ( ɛ r) of LiF/CuO-codoped BaTiO3 was 1620 at 1 MHz, and the temperature coefficient of capacitance satisfied the X5R specification. After cofiring this LiF/CuO-codoped BaTiO3 ceramic with an MLS-22 sheet at 860°C, there was no crack formation at the layer boundary. Also a chemical compatibility test revealed that there were no severe reactions between the LiF/CuO-codoped BaTiO3 and an Ag electrode.

  4. Extraction of potassium from biotite by Ba2+/K+ ion exchange and the structural transformation

    NASA Astrophysics Data System (ADS)

    Meng, Peng; Li, Ziqian; Huang, Zhiliang; Chen, Changlian

    2016-06-01

    Potassium has been extracted successfully from biotite by Ba2+/K+ ion exchange. The potassium release rate increased along S-curve versus reaction time. The maximum of potassium release rate was about 96 %. Powder X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy were used to characterize the obtained samples to reveal the exchanging behavior and structural transformation. The results showed that after treated with Ba(NO3)2 four times the original biotite transformed to vermiculite-type hydrated Ba-mica. The (001) basal plane was expanded from 1.000 nm of biotite to 1.221 nm of hydrated Ba-mica. Because of the "vacancy effect," the Ba2+ has two different statuses, causing the structural water vibration of vermiculite-type hydrated Ba-mica split. The edge of vermiculite-type hydrated Ba-mica was crimped compared with the flat edge of original biotite. The (001) basal plane of dehydrated Ba-mica was also split, supporting the "vacancy effect."

  5. Preparation and Properties of Ce3+:BaF2 Transparent Ceramics by Vacuum Sintering.

    PubMed

    Luo, Junming; Ye, Lifang; Xu, Jilin

    2016-04-01

    Ce0.001Ba0.999F2.001 powders were prepared by a chemical coprecipitation method using Ba(N03)2, KF.2H2O and Ce(NO3)3 6H20 as raw materials. Ce0.001Ba0.999F2.001 transparent ceramics were prepared by vacuum sintering. The results show that the Ce0.001Ba0.999F2.001 powders were blocky, and both powdered and sintered transparent ceramics were composed of BaF2 phases without the secondary phase. The maximum light transmittance of the Ce0.001Ba0.999F2.001 transparent ceramics reached 55%. The fracture morphology shows a cleavage fracture with a few micropores. The fluorescence spectra show that the Ce0.1Ba0.999F2.001 powders displayed emissions at 410 nm, 480 nm and 620 nm under 275 nm excitation. The Ce0.1Ba0.9F2.1 transparent ceramics displayed0emissions at 450 nm and 620 nm under 294 nm excitation. PMID:27451752

  6. Luminescence and Site Occupancy of Eu2+ in Ba2 Ca(BO3)2

    NASA Astrophysics Data System (ADS)

    Li, Pan-Lai; Wang, Zhi-Jun; Yang, Zhi-Ping; Guo, Qing-Lin

    2011-01-01

    A green phosphor Ba2Ca(BO3)2:Eu2+ was synthesized by a high temperature solid-state reaction method under a reductive atmosphere. The luminescence and site occupancy of Eu2+ in Ba2Ca(BO3)2 are investigated. Ba2Ca(BO3)2:Eu2+ shows one green band (537 nm) under 400 nm near ultraviolet excitation which is suitable for UV LED. Ca2+ and Ba2+ ions in Ba2Ca(BO3)2 are replaced by Eu2+ ions, the Ba2Ca(BO3)2:Eu2+ shows a dissymmetrical emission band. The influence of Eu2+ doping concentrations on the emission intensity of Ba2Ca(BO3)2:Eu2+ is studied. It is found that the emission intensity is influenced by the Eu2+ concentration and reaches the maximum value at 2% Eu2+. According to the Dexter theory, the concentration quenching mechanisms of Eu2+ in Ba2Ca(BO3)2 are the d-dinteraction.

  7. Dipole strength distributions in the stable Ba isotopes 134 138 Ba : A study in the mass region of a nuclear shape transition

    NASA Astrophysics Data System (ADS)

    Scheck, M.; von Garrel, H.; Tsoneva, N.; Belic, D.; von Brentano, P.; Fransen, C.; Gade, A.; Jolie, J.; Kneissl, U.; Kohstall, C.; Linnemann, A.; Nord, A.; Pietralla, N.; Pitz, H. H.; Stedile, F.; Stoyanov, C.; Werner, V.

    2004-10-01

    The low-lying dipole strength distributions in the odd-mass isotopes 135,137 Ba were studied in nuclear resonance fluorescence experiments (NRF) performed at the Stuttgart Dynamitron facility using bremsstrahlung beams with end point energies of 4.1, 3.1, and 2.5 MeV . Numerous excited states, most of them unknown so far, were observed in the excitation energy range up to 4 MeV . Detailed spectroscopic information has been obtained on excitation energies, decay widths, decay branching ratios, and transition probabilities. The results for 137Ba are compared with calculations in the framework of the Quasiparticle-Phonon Model. The new data for 135,137 Ba complete the systematics of low-lying dipole excitations as observed for the even Ba isotopes 134,136,138 Ba in previous NRF experiments in Stuttgart. The complete systematics within the Ba isotopic chain, exhibiting a nuclear shape transition, is discussed with respect to E1 two-phonon excitations, M1 scissors mode excitations, and in regard to the new critical point symmetries.

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

    SciTech Connect

    Miller, D.; Richards, P.L. ); Garrison, S.M.; Newman, N. ); Eom, C.B.; Geballe, T.H. . Dept. of Applied Physics); Etemad, S.; Inam, A.; Venkatesan, T. ); Martens, J.S. (Sandia National Labs., Albuquerque, NM (Unite

    1992-03-01

    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{sub 2}Cu{sub 3}O{sub 7}, Tl{sub 2}Ca{sub 2}Ba{sub 2}Cu{sub 3}O{sub 10} and Tl{sub 2}CaBa{sub 2}Cu{sub 2}O{sub 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 {approximately} 1 THz. We are able to fit the losses in the Y-Ba-Cu-O films to a weakly coupled grain model for the a-b plane conductivity, in good agreement with results from a Kramers-Kronig analysis of the loss data. We observe strong phonon structure in the Tl-Ca-Ba-Cu-O films for frequencies between 2 and 21 THz, and are unable to fit these losses to the simple weakly coupled grain model. This is in strong contrast to the case for other high {Tc} superconductors such as YBa{sub 2}Cu{sub 3}O{sub 7}, where phonon structure observed in ceramic samples is absent in epitaxial oriented films and crystals because of the electronic screening due to the high conductivity of the a-b planes.

  9. Direct spectroscopic evidence for completely filled Cu 3d shell in BaCu₂As₂ and α – BaCu₂Sb₂

    DOE PAGES

    Wu, S. F.; Richard, P.; van Roekeghem, A.; Nie, S. M.; Miao, H.; Xu, N.; Qian, T.; Saparov, B.; Fang, Z.; Biermann, S.; et al

    2015-06-08

    We use angle-resolved photoemission spectroscopy to extract the band dispersion and the Fermi surface of BaCu₂As₂ and α - BaCu₂Sb₂. While the Cu 3d bands in both materials are located around 3.5 eV below the Fermi level, the low-energy photoemission intensity mainly comes from As 4p states, suggesting a completely filled Cu 3d shell. The splitting of the As 3d core levels and the lack of pronounced three-dimensionality in the measured band structure of BaCu₂As₂ indicate a surface state likely induced by the cleavage of this material in the collapsed tetragonal phase, which is consistent with our observation of amore » Cu⁺¹ oxidation state. However, the observation of Cu states at similar energy in α - BaCu₂Sb₂ without the pnictide-pnictide interlayer bonding characteristic of the collapsed tetragonal phase suggests that the short interlayer distance in BaCu₂As₂ follows from the stability of the Cu⁺¹ rather than the other way around. Our results confirm the prediction that BaCu₂As₂ is an sp metal with weak electronic correlations.« less

  10. Direct spectroscopic evidence for completely filled Cu 3d shell in BaCu₂As₂ and α – BaCu₂Sb₂

    SciTech Connect

    Wu, S. F.; Richard, P.; van Roekeghem, A.; Nie, S. M.; Miao, H.; Xu, N.; Qian, T.; Saparov, B.; Fang, Z.; Biermann, S.; Sefat, Athena S.; Ding, H.

    2015-06-08

    We use angle-resolved photoemission spectroscopy to extract the band dispersion and the Fermi surface of BaCu₂As₂ and α - BaCu₂Sb₂. While the Cu 3d bands in both materials are located around 3.5 eV below the Fermi level, the low-energy photoemission intensity mainly comes from As 4p states, suggesting a completely filled Cu 3d shell. The splitting of the As 3d core levels and the lack of pronounced three-dimensionality in the measured band structure of BaCu₂As₂ indicate a surface state likely induced by the cleavage of this material in the collapsed tetragonal phase, which is consistent with our observation of a Cu⁺¹ oxidation state. However, the observation of Cu states at similar energy in α - BaCu₂Sb₂ without the pnictide-pnictide interlayer bonding characteristic of the collapsed tetragonal phase suggests that the short interlayer distance in BaCu₂As₂ follows from the stability of the Cu⁺¹ rather than the other way around. Our results confirm the prediction that BaCu₂As₂ is an sp metal with weak electronic correlations.

  11. Ba11La4Br34: a new barium lanthanum bromide

    PubMed Central

    Eagleman, Yetta; Wu, Guang; Gundiah, Gautam; Bourret-Courchesne, Edith; Derenzo, Stephen

    2011-01-01

    The structure of the title compound, barium lanthanum bromide (11/4/34), can be derived from the fluorite structure. The asymmetric unit contains two Ba sites (one with site symmetry 4/m..), one La site (site symmetry 4..), one mixed-occupied Ba and La site (ratio 1:1, site symmetry m..) and six Br sites (one with site symmetry \\=4.., one with 2.., one with m.., the latter being disordered over two positions with a 0.86:0.14 ratio). The fundamental building units of the structure are edge-sharing polyhedral clusters made up of Ba and La bromide clusters inter­connected to BaBr8 square prisms and BaBr10 groups. PMID:22064368

  12. The Structural Disorder and Lattice Stability of (Ba,Sr)(Co,Fe)O3 Complex Perovskites

    SciTech Connect

    S.N.Rashkeev

    2011-05-01

    The structural disorder and lattice stability of complex perovskite (Ba,Sr)(Co,Fe)O3, a promising cathode material for solid oxide fuel cells and oxygen permeation membranes, is explored by means of first principles DFT calculations. It is predicted that Ba and Sr ions easily exchange their lattice positions (A-cation disorder) similarly to Co and Fe ions (B-cation disorder). The cation antisite defects (exchange of A- and B-type cations) have a relatively high formation energy. The BSCF is predicted to exist in an equilibrium mixture of several phases and can decompose exothermically into the Ba- and Co-rich hexagonal (Ba,Sr)CoO3 and Sr- and Fe-rich cubic (Ba,Sr)FeO3 perovskites.

  13. Effects of Oxide Additives to (Ba,Sr)TiO3 Ceramics Fired under Reduced Atmosphere

    NASA Astrophysics Data System (ADS)

    Sakai, Y.; Futakuchi, T.; Adachi, M.

    2011-10-01

    Ba0.6Sr0.4TiO3 doped with MgO, CaO, SrO, or BaO thick films with Ni electrodes were prepared by screen printing. The prepared thick films showed a perovskite single phase. TC was changed corresponding to the kinds of doping oxides. The tunability and tanδ value of thick films doping with 2 mol% of BaO or CaO at an electric field of 10 V/μm were approximately 85% and 0.3%, respectively. The leakage current of Ba0.6Sr0.4TiO3 thick films doped with 2 mol% of BaO thick films at 10 V/μm was less than 10-6 A/cm2 and the value was less than that of thick films doped with 2 mol% of CaO.

  14. Greatly enhanced magnetic properties of electrodeposited Ni-Co-P-BaFe12O19 composites

    NASA Astrophysics Data System (ADS)

    El-Sayed, Adly H.; Hemeda, O. M.; Tawfik, A.; Hamad, Mahmoud A.

    2016-03-01

    We prepared electrodeposited Ni-Co-P-M-type BaFe12O19 (BaM) film as magnetic soft-hard composites with a large amount of entrapped BaM particles more than 40 wt% were grown over polycrystalline copper substrates. The results show that the saturation magnetization of BaM particles remarkably increases by more than 300% and Mr increases by more than 700% when they embedded into the Ni-Co-P metal. In contrast to previous reports, it is clear that values of coercivity and squareness for our work are significantly better than corresponding values obtained for electrodeposited Ni-Co-BaM composite films of previous works.

  15. Ab initio structure determination of new compound Ba 3(BO 3)(PO 4)

    NASA Astrophysics Data System (ADS)

    Ma, H. W.; Liang, J. K.; Wu, L.; Liu, G. Y.; Rao, G. H.; Chen, X. L.

    2004-10-01

    The crystal structure of new compound Ba3BPO7 was determined by ab initio method from high-resolution conventional X-ray powder diffraction data. The Rietveld refinement converged to Rp=5.92%, Rwp=8.87%, Rexp=5.00% with the following details: Hexagonal, space group P63mc, a=5.4898 (1) Å, c=14.7551(1) Å, Z=2. The basic unit of the structure is the [BaO10]-[BO3]-[PO4] polar polyhedra-chain composed of Ba1-B-P-O cluster. These chains, running along c-axis, stack in a HCP mode to build the whole structure with triangular prism channels. The channels are parallel to c-axis too, in which Ba2 and Ba3 are located.

  16. On the existence of a homologous series of Ba mCu m+nO y oxides with the cubic structure of the BaCuO 2 oxide

    NASA Astrophysics Data System (ADS)

    Klinkova, L. A.; Nikolaichik, V. I.; Barkovskii, N. V.; Fedotov, V. K.

    2010-12-01

    Phase relations have been studied in the BaO-CuO x system in the range of 42.0-83.0 mol.% CuO at P(O 2) = 21 kPa (air) by visual polythermal analysis (VPA), powder X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TGA), chemical analysis (CA), and electron diffraction (ED) with simultaneous elemental analysis (EA) in a transmission electron microscope (TEM). The existence of discrete crystallization fields of barium-copper oxides of cation compositions Ba 4Cu 5O y, Ba 5Cu 6O y, Ba 7Cu 8O y, Ba 12Cu 13O y, and Ba 24Cu 25O y, which have the cubic structure of the BaCuO 2 oxide, is revealed in the studied region of the system. The oxides may be represented as members of a Ba mCu m+nO y homologous series. The BaCuO 2 oxide does not exist in the subsolidus region and does not have its own crystallization field. The oxygen-deficient oxide BaCuO 1.78 of the cation composition (Ba:Cu) 1:1 with the BaCuO 2 cubic structure is found in melted samples of the 50.0 mol.% CuO composition quenched at 1020-1060 °С.

  17. The oxidation of Ba dosed Mo(100) surfaces with O/sub 2/ at moderately high temperatures

    SciTech Connect

    Rogers, J.W. Jr.; Blair, D.S.; Paffett, M.T.

    1987-01-01

    The oxidation of Mo(100) and Ba-covered Mo(100) by O/sub 2/ have been examined at moderately high temperature (700 to 1400/sup 0/K) using x-ray photoelectron spectroscopy. Results indicate that the Ba or BaO overlayer retards but does not prevent oxidation of the underlying Mo surface. The high temperature surface chemistry of the O/Ba/Mo surface is described. 11 refs., 3 figs.

  18. Ba/Ca Ratios in North Pacific Bamboo Corals Record Changes in Intermediate Water Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Serrato Marks, G.; LaVigne, M.; Hill, T. M.; Sauthoff, W.; Guilderson, T. P.; Roark, E. B.; Dunbar, R. B.

    2015-12-01

    Trace elemental ratios preserved in the skeleton of bamboo corals, which live for hundreds of years at >500m depth, have been utilized as archives of deep-ocean conditions. However, it was previously unclear whether trace element data from these corals were internally reproducible and could therefore be used as reliable climate proxies. This study tests the internal reproducibility of Ba/Ca in the calcite of nine bamboo corals to further develop a new proxy for dissolved Ba in seawater (BaSW). Trace element LA-ICP-MS data were collected along three replicate radii of varying lengths of the calcitic internodes of well-dated corals collected live from the Gulf of Alaska (720m and 643m) and the California Margin (870m, 1012m, 1295m, 1500m, 1521m, 1954m, and 2054m; samples from 1295-1521m are not yet dated). Data were aligned using visible bands measured with a petrographic microscope to account for irregular growth. Ba/Ca data filtered with a 50μm (1.5-2 year) moving average were reproducible within each coral to 2.9 ± 2.1% (n=3 radii/coral, 9 corals), suggesting that regional geochemical signals are recorded as reproducible Ba/Ca signals on >annual timescales. Coral Ba/Ca presents an excellent proxy for BaSW, which has been found to be correlated with refractory nutrients (e.g. silicate) and oxygen minima. Increasing BaSW with depth and increased variability near 1000m suggests that BaSW is not constant with depth or with time. Several factors, including barite saturation state, particulate organic carbon (POC) remineralization rate, and particle sinking time, may be involved in the observed changes in BaSW. Further examination of such mechanisms could provide new insights into modern changes in deep-sea biogeochemistry.

  19. Catalytic decomposition of Ba(NO3)2 on Pt(111)

    SciTech Connect

    Mudiyanselage, Kumudu; Weaver, Jason F.; Szanyi, Janos

    2011-04-07

    The decomposition of Ba(NO3)2 formed on BaO/Pt(111) (Pt(111) surface is partially covered by BaO) in the presence of CO was studied using temperature programmed desorption (TPD), infrared reflection absorption (IRA) and X-ray photoelectron (XP) spectroscopies. The exposure of BaO/Pt(111) to elevated NO2 pressure (1.0×10-4 Torr) at 450 K leads to the formation of Ba(NO3)2, chemisorbed O (OPt) and Pt-oxide-like domains. During TPD, the Ba(NO3)2 begins to thermally decompose near 490 K, releasing NO and NO2 with the maximum NOx desorption rate seen at 605 K. The OPt species formed following the exposure of BaO/Pt(111) to NO2 react with CO to release CO2 at 450 K. The consumption of OPt during CO oxidation initiates the migration of O from the Pt-oxide-like domains to the chemisorbed phase, where the CO oxidation reaction occurs. Therefore, the removal of OPt by CO leads to the reduction of oxidized Pt, and to the formation of metallic Pt(111) domains, where, subsequently, catalytic decomposition of Ba(NO3)2 can take place. The Pt-catalyzed decomposition of Ba(NO3)2 occurs readily at 450 K, a temperature much lower than the onset of the decomposition temperature of Ba(NO3)2 in the presence of oxidized Pt. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  20. Structural insight into the E. coli HigBA complex.

    PubMed

    Yang, Jingsi; Zhou, Ke; Liu, Peng; Dong, Yuhui; Gao, Zengqiang; Zhang, Jianjun; Liu, Quansheng

    2016-09-30

    The toxin-antitoxin system is ubiquitously existed in bacteria and archaea, performing a wide variety of functions modulating cell fitness in response to environmental cues. In this report, we solved the crystal structure of the toxin-antitoxin HigBA complex from E. coli K-12 to 2.7 Å resolution. The crystal structure of the HigBA complex displays a hetero-tetramer (HigBA)2 form comprised by two HigB and two HigA subunits. Each toxin HigB resumes a microbial RNase T1 fold, characteristic of a three antiparallel β-sheet core shielded by a few α-helices at either side. Each antitoxin HigA composed of all α-helices resembles a "C"-shaped clamp nicely encompassing a HigB in the (HigBA)2 complex. Two HigA monomers dimerize at their N-terminal domain. We showed that HigA helix α1 was essential for HigA dimerization and the hetero-tetramer (HigBA)2 formation, but not for a hetero-dimeric HigBA formation. HigA dimerization mediated by helix α1 was dispensable for DNA-binding, as a heterodimeric HigBA complex still bound to the higBA operator in vitro. The HigA C-terminal domain with a helix-turn-helix fold was essential for DNA binding. We also defined two palindromes in higBA operator specifically recognized by HigA and HigBA in vitro. PMID:27601326

  1. Draft Genome Sequence of Bacillus pumilus BA06, a Producer of Alkaline Serine Protease with Leather-Dehairing Function

    PubMed Central

    Zhao, Chuan-Wu; Wang, Hai-Yan; Zhang, Yi-Zheng

    2012-01-01

    Bacillus pumilus BA06 was isolated from the proteinaceous soil and produced an extracellular alkaline protease with leather-dehairing function. The genome of BA06 was sequenced. The comparative genome analysis indicated that strain BA06 is different in genome from the other B. pumilus strains, with limited insertions, deletions, and rearrangements. PMID:23144411

  2. U, Ra and Ba incorporation during precipitation of hydrothermal carbonates: Implications for {sup 226}Ra-Ba dating of impure travertines

    SciTech Connect

    Rihs, S.; Condomines, M.; Sigmarsson, O.

    2000-02-01

    The authors studied U, Ra and Ba incorporation in calcite in a natural CO{sub 2}-rich hydrothermal area from the French Massif Central. Along the western border of the Limagne graben, several springs are exploited for the petrification of various artifacts with calcite. These sites offer the opportunity to sample the water and the calcite layers downflow from the spring, and thus to follow the evolution of their U, Ra and Ba contents as precipitation proceeds. Results show that the apparent partition coefficients of U, Ra and Ba between water and calcite decrease during precipitation for the three elements. The authors found no direct relation between this variation and the main factors able to influence the partition coefficient, such as precipitation rate, which suggests that the incorporation of these trace elements could result from a composite process of adsorption and coprecipitation. Ra and Ba have a similar behavior, with an apparent partition coefficient decreasing from 0.80 to 0.47 for Ra and 0.96 to 0.68 for Ba, resulting in a small ({le}10%) variation of the Ra/Ba ratio. The apparent partition coefficient of U decreases from 0.38 to 0.20. These apparent coefficients are much higher than equilibrium values but might be applicable to natural systems with high precipitation rates. The authors also investigated the possibility of using the decay of the {sup 226}Ra-excess, or the decrease of the ({sup 226}Ra)/Ba ratio to date older deposits. Whereas the {sup 226}Ra initial activity at the time of deposition has not remained constant, and cannot be used for dating, the ({sup 226}Ra)/Ba method gives better results, when appropriate corrections for detrital contamination in Ba are made. Mixing diagrams using Th as an indicator of contamination allow calculation of the ({sup 226}Ra)/Ba ratio of the pure carbonate component. The calculated ages of five travertine layers range from 330 to 800 years, suggesting a mean deposition rate of about 1 cm/yr. The

  3. Investigation of structural, mechanical, electronic, optical, and dynamical properties of cubic BaLiF3, BaLiH3, and SrLiH3

    NASA Astrophysics Data System (ADS)

    Yalcin, Battal G.; Salmankurt, Bahadır; Duman, Sıtkı

    2016-03-01

    The structural, mechanical, electronic, optical, and dynamical properties of BaLiF3, BaLiH3, and SrLiH3 cubic perovskite materials are theoretically investigated by using first principles calculations. Obtained results are in reasonable agreement with other available theoretical and experimental studies. The considered materials are found to be mechanically stable in the cubic structure. We found that all materials are brittle. The modified Becke-Johnson (mBJ) exchange potential has been used here to obtain an accurate band order. The calculated band-gap energy value of BaLiF3 (8.26 eV) within the mBJ potential agrees very well with the experimentally reported value of 8.41 eV. In order to have a deeper understanding of the bonding mechanism and the effect of atomic relaxation on the electronic band structure, the total and partial density of states have also been calculated. We have investigated the fundamental optical properties, such as the real ɛ 1(ω) and imaginary ɛ 2(ω) parts of the dielectric function, absorption coefficient α(ω), reflectivity R(ω), and refractive index n(ω) in the energy range from 0 to 40 eV within the mBJ potential. The band-gap energy obtained from the absorption spectrum is around 8.76, 3.99, and 3.31 eV for BaLiF3, BaLiH3, and SrLiH3 crystals, respectively. It should be noted that BaLiF3 could be a strong potential candidate as a laser material for the development of a vacuum-ultraviolet light emitting diode once direct transition is confirmed by experimental studies. Finally, we have calculated the lattice dynamical properties of BaLiF3, BaLiH3, SrLiH3, and SrLiF3 crystals. The full phonon dispersion curves of these materials are reported for the first time. Our results clearly indicate that the materials are dynamically stable, except for SrLiF3, in the cubic structure. The obtained zone-center phonon frequencies of BaLiF3, BaLiH3, and SrLiH3 accord very well with previous experimental measurements.

  4. CVD Diamonds in the BaBar Radiation Monitoring System

    NASA Astrophysics Data System (ADS)

    Bruinsma, M.; Burchat, P.; Edwards, A. J.; Kagan, H.; Kass, R.; Kirkby, D.; Petersen, B. A.

    2006-01-01

    To prevent excessive radiation damage to its Silicon Vertex Tracker, the BaBar experiment at SLAC uses a radiation monitoring and protection system that triggers a beam abort whenever radiation levels are anomalously high. The existing system, which employs large area Si PIN diodes as radiation sensors, has become increasingly difficult to operate due to radiation damage. We have studied CVD diamond sensors as a potential alternative for these silicon sensors. Two diamond sensors have been routinely used since their installation in the Vertex Tracker in August 2002. The experience with these sensors and a variety of tests in the laboratory have shown CVD diamonds to be a viable solution for dosimetry in high radiation environments. However, our studies have also revealed surprising side-effects.

  5. Dielectric response of polystyrene - BaTiO3 nanocomposites

    NASA Astrophysics Data System (ADS)

    Korotkova, Tatyana N.; Sysoev, Oleg I.; Belov, Pavel A.; Emelianov, Nikita A.; Velyaev, Yury O.; Mandalawi, Wissam M. Al; Korotkov, Leonid N.

    2016-07-01

    The series of composite materials based on polystyrene and non-ferroelectric BaTiO3 nanoparticles ((1-x)PS-xBT, where the volume concentration x = 0-1.0) was prepared. Their dielectric properties were studied within the temperature range 20-160 °C at the frequency of 100 kHz. It is found that an increase in the barium titanate concentration leads to increase of the both dielectric permittivity (ɛ) and dielectric losses (tgδ). The concentration dependence of ɛ can be described by the modified Kerner model. It was found that the glass transition in polystyrene matrix is diffused and its temperature is increased with concentration x.

  6. Experience with the BaBar Resistive Plate Chambers

    SciTech Connect

    Band, H.

    2005-04-06

    The BaBar detector has operated over 2000 m{sup 2} of Resistive Plates Chambers (RPCs) as muon and neutral hadron detectors since 1999. Most of the original RPC production have lost significant efficiency and many are now completely inefficient. Both the linseed oil used to coat the inner surfaces and the graphite coating on the outer surfaces are implicated as contributors to the efficiency loss which was accelerated by the operation of the RPCs at 29 to 34 C during the first summer. RPCs from 2 more recent production runs have been installed and tested. The most recent RPCs have exhibited stable efficiencies and high voltage plateaus during the first 8 months of service. Some have shown increased dark currents and noise rates.

  7. A wideband analog correlator system for AMiBA

    NASA Astrophysics Data System (ADS)

    Li, Chao-Te; Kubo, Derek; Han, Chih-Chiang; Chen, Chung-Cheng; Chen, Ming-Tang; Lien, Chun-Hsien; Wang, Huei; Wei, Ray-Ming; Yang, Chia-Hsiang; Chiueh, Tzi-Dar; Peterson, Jeffrey; Kesteven, Michael; Wilson, Warwick

    2004-10-01

    A wideband correlator system with a bandwidth of 16 GHz or more is required for Array for Microwave Background Anisotropy (AMiBA) to achieve the sensitivity of 10μK in one hour of observation. Double-balanced diode mixers were used as multipliers in 4-lag correlator modules. Several wideband modules were developed for IF signal distribution between receivers and correlators. Correlator outputs were amplified, and digitized by voltage-to-frequency converters. Data acquisition circuits were designed using field programmable gate arrays (FPGA). Subsequent data transfer and control software were based on the configuration for Australia Telescope Compact Array. Transform matrix method will be adopted during calibration to take into account the phase and amplitude variations of analog devices across the passband.

  8. The New BaBar Data Reconstruction Control System

    SciTech Connect

    Ceseracciu, Antonio

    2003-06-02

    The BaBar experiment is characterized by extremely high luminosity, a complex detector, and a huge data volume, with increasing requirements each year. To fulfill these requirements a new control system has been designed and developed for the offline data reconstruction system. The new control system described in this paper provides the performance and flexibility needed to manage a large number of small computing farms, and takes full benefit of OO design. The infrastructure is well isolated from the processing layer, it is generic and flexible, based on a light framework providing message passing and cooperative multitasking. The system is actively distributed, enforces the separation between different processing tiers by using different naming domains, and glues them together by dedicated brokers. It provides a powerful Finite State Machine framework to describe custom processing models in a simple regular language. This paper describes this new control system, currently in use at SLAC and Padova on {approx}450 CPUs organized in 12 farms.

  9. muSR in Ba2CoO4

    NASA Astrophysics Data System (ADS)

    Russo, Peter; Sugiyama, Jun; Ansaldo, Eduardo; Brewer, Jess; Stubbs, Scott; Chow, Kim; Jin, R.; Sha, H.; Zhang, J.

    2008-03-01

    A positive muon spin rotation and relaxation (&+circ;SR) experiment on the single crystal Ba2CoO4 indicates the existence of an antiferromagnetic (AF) transition occurring at TN˜25 K. Weak transverse field measurements (wTF-&+circ;SR) show that the paramagnetic volume fraction of the sample decreases rapidly at the magnetic transition indicating a bulk effect. Zero field measurements (ZF-&+circ;SR) show the presence of a magnetically ordered state below TN. The results are compared to recent magnetic susceptibility and neutron measurements. Although there are two possible AF spin structures proposed by recent neutron experiments, the μSR results clearly exclude AF order along the c-axis while supporting AF order in the ab plane.

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

    PubMed Central

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

    2014-01-01

    Background: 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. Objectives: 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. Patients and Methods: 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. Results: 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. Conclusions: The adoption of 85 dBA as the permissible exposure

  11. Multiferroic properties of nanocrystalline BaTiO 3

    NASA Astrophysics Data System (ADS)

    Mangalam, R. V. K.; Ray, Nirat; Waghmare, Umesh V.; Sundaresan, A.; Rao, C. N. R.

    2009-01-01

    Some of the Multiferroics [H. Schmid, Ferroelectrics 162 (1994) 317] form a rare class of materials that exhibit magneto-electric coupling arising from the coexistence of ferromagnetism and ferroelectricity, with potential for many technological applications [J.F. Scott, Nat. Mater. 6 (2007) 256; N.A. Spaldin, M. Fiebig, Science 309 (2005) 391]. Over the last decade, an active research on multiferroics has resulted in the identification of a few routes that lead to multiferroicity in bulk materials [C. Ederer, N.A. Spaldin, Nat. Mater. 3 (2004) 849; D.V. Efremov, J. van den Brink, D.I. Khomskii, Nat. Mater. 3 (2004) 853; N. Hur, S. Park, P.A. Sharma, J.S. Ahn, S. Guha, S.W. Cheong, Nature 429 (2004) 392]. While ferroelectricity in a classic ferroelectric such as BaTiO 3 is expected to diminish with the reducing particle size, [C.H. Ahn, K.M. Rabe, J.M. Triscone, Science 303 (2004) 488; J. Junquera, P. Ghosez, Nature 422 (2003) 506] ferromagnetism cannot occur in its bulk form [N.A. Hill, J. Phys. Chem. B 104 (2000) 6694]. Here, we use a combination of experiment and first-principles simulations to demonstrate that multiferroic nature emerges in intermediate size nanocrystalline BaTiO 3, ferromagnetism arising from the oxygen vacancies at the surface and ferroelectricity from the core. A strong coupling between a surface polar phonon and spin is shown to result in a magnetocapacitance effect observed at room temperature, which can open up possibilities of new electro-magneto-mechanical devices at the nano-scale.

  12. Activity and diffusivity of oxygen in liquid Ag-Yb1Ba2Cu3 and Tl1Ba2Ca2Cu3 alloys

    NASA Astrophysics Data System (ADS)

    Chou, H.; Chen, H. S.; Fang, W. C.; Wu, M. K.

    1992-12-01

    We have measured the activity and diffusivity of oxygen in liquid Ag-Yb1Ba2Cu3 and Tl1Ba2Ca2Cu3 at 930 and 900 °C, respectively, by a modified coulometric titration method on the galvanic cell: O_ in liquid alloys/yttria stabilized zirconia/air, Pt. The standard Gibbs formation energy and the diffusivity of oxygen in liquid Ag-Yb1Ba2Cu3 alloy for 1/2O2(1 atm)→O_(1 at. %) are determined to be ΔG=-247.4 kJ/g atom, and D=1.52×10-4 cm2/s. The oxygen solubility Cs in the Ag-Yb1Ba2Cu3 alloy is 0.0913 at. %, a factor of 5.5 higher than that in Yb1Ba2Cu3 alloy. The addition of Ag does not alter the growth mechanism and the oxygen diffusion controls the film growth. The growth speed is enhanced as a result of the enhanced oxygen solubility. ΔG and the diffusion coefficient of oxygen in the Tl1Ba2Ca2Cu3 liquid alloy are -257 kJ/g atom and 1.2×10-4 cm2/s, respectively. The oxygen solubility of the Tl1Ba2Ca2Cu3 alloy at 900 °C is found to be very high at ˜5.74 at. %. All thermodynamic data for oxygen in the precursor alloys are consistent with each other but there is a deviation of activity coefficient with composition for the different alloys from the theoretical model.

  13. Benzo[a]pyrene (BaP) metabolites and 1-hydroxypyrene as urinary biomarkers for human environmental exposure to BaP

    SciTech Connect

    Buckley, T.J.

    1991-01-01

    Environmental exposures to benzo[a]pyrene (BaP) through inhalation and ingestion pathways and the corresponding elimination of BaP metabolites in the urine were evaluated through regression and mass balance models. Personal air sampling (24-h) yielded BaP inhalation dose estimates of 11.0 and 2.3 ng/d for winter and late summer, respectively, while duplicate plate sampling yielded an ingested dose estimate of 176 ng/d. The daily inhalation dose was exceeded by the ingested dose by median factors of 6 and 122 for the respective study phases. Using the reverse metabolism method of analysis, median urinary BaP metabolite elimination rates were 121 and 129 ng/d for Phase 2 and 3, respectively. BaP dose (inhalation and ingestion) and urinary BaP metabolite elimination variables were related using multiple linear regression. When the difference between week 1 and 2 in dose and metabolite elimination was considered, and when body weight was included, a statistically significant model was determined (r = 0.620, p = 0.015, n = 25) with most of the variation in urine elimination being explained by ingested dose. A separate controlled exposure study was conducted among five nonsmoking males to define the time-course of urinary 1-hydroxypyrene (1-OHPY) elimination associated with ingestion of foods containing polycyclic aromatic hydrocarbons (PAHs). This investigation showed that a 100-250 fold increase in the dietary BaP does paralleled to 4 to 12 fold increase in the elimination of 1-OHPY. A biexponential model was fitted to the 1-OHPY elimination rate data yielding an average half-life estimate of 4.4 h and an average time of maximal rate of elimination of 6.3 h after the ingested dose.

  14. First principles investigations of structural, elastic, dielectric and piezoelectric properties of { Ba,Sr,Pb } TiO3, { Ba,Sr,Pb } ZrO3 and { Ba,Sr,Pb } { Zr,Ti } O3 ceramics

    NASA Astrophysics Data System (ADS)

    Akgenc, Berna; Tasseven, Cetin; Cagin, Tahir

    2015-03-01

    We use first-principle density-functional study of structural, anisotropic mechanical, dielectric and piezoelectric properties of {Ba,Sr,Pb}TiO3, {Ba,Sr,Pb}ZrO3 and {Ba,Sr,Pb}{Zr,Ti}O3 alloys in cubic perovskite structures at zero temperature. Because there is significant interest in finding new piezoelectrics that do not contain toxic elements such as lead. In this study, we compare piezoelectric response of those alloys to synthesize outstanding piezoelectric materials. In perovskite structures, the spontaneous polarization is due to enormous values of Born effective charges computed by linear response within density functional perturbation theory, which are much larger than predicted nominal charge. We deeply investigated the effects of composition, order and site defects structure on piezoelectric constants.

  15. Facile synthesis of BaTiO3 nanotubes and their microwave absorption properties.

    PubMed

    Zhu, Yao-Feng; Zhang, Li; Natsuki, Toshiaki; Fu, Ya-Qin; Ni, Qing-Qing

    2012-04-01

    Uniform BaTiO(3) nanotubes were synthesized via a simple wet chemical route at low temperature (50 °C). The as-synthesized BaTiO(3) nanotubes were characterized using powder X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The results show that the BaTiO(3) nanotubes formed a cubic phase with an average diameter of ~10 nm and wall thickness of 3 nm at room temperature. The composition of the mixed solvent (ethanol and deionized water) was a key factor in the formation of these nanotubes; we discuss possible synthetic mechanisms. The microwave absorption properties of the BaTiO(3) nanotubes were studied at microwave frequencies between 0.5 and 15 GHz. The minimum reflection loss of the BaTiO(3) nanotubes/paraffin wax composite (BaTiO(3) nanotubes weight fraction = 70%) reached 21.8 dB (~99.99% absorption) at 15 GHz, and the frequency bandwidth less than -10 dB is from 13.3 to 15 GHz. The excellent absorption property of BaTiO(3) nanotubes at high frequency indicates that these nanotubes could be promising microwave-absorbing materials. PMID:22409350

  16. Low affinity block of native and cloned hyperpolarization-activated Ih channels by Ba2+ ions.

    PubMed

    van Welie, Ingrid; Wadman, Wytse J; van Hooft, Johannes A

    2005-01-10

    Ba2+ is commonly used to discriminate two classes of ion currents. The classical inward-rectifying K+ current, I(Kir), is blocked by low millimolar concentrations of Ba2+, whereas the hyperpolarization-activated cation current, I(h), is assumed not to be sensitive to Ba2+. Here we investigated the effects of Ba2+ on I(h) currents recorded from rat hippocampal CA1 pyramidal neurons, and on cloned I(h) channels composed of either HCN1 or HCN2 subunits transiently expressed in Human Embryonic Kidney (HEK) 293 cells. The results show that low millimolar concentrations of Ba2+ reduce the maximal I(h) conductance (IC50 approximately 3-5 mM) in both CA1 pyramidal neurons and in HEK 293 cells without specificity for HCN1 or HCN2 subunits. In addition, Ba2+ decreases the rate of activation and increases the rate of deactivation of I(h) currents. Neither the half-maximal voltage of activation, V(h), nor the reversal potential of the I(h) channels were affected by Ba2+. The combined results suggest that B2+, at concentrations commonly used to block I(Kir) currents, also reduces the conductance of I(h) channels without subunit specificity, and affects the kinetics of I(h) channel gating.

  17. Graphene oxide-BaGdF5 nanocomposites for multi-modal imaging and photothermal therapy.

    PubMed

    Zhang, Hao; Wu, Huixia; Wang, Jun; Yang, Yan; Wu, Dongmei; Zhang, Yingjian; Zhang, Yang; Zhou, Zhiguo; Yang, Shiping

    2015-02-01

    By using a solvothermal method in the presence of polyethylene glycol (PEG), BaGdF5 nanoparticles are firmly attached on the surface of graphene oxide (GO) nanosheets to form the GO/BaGdF5/PEG nanocomposites. The resulting GO/BaGdF5/PEG shows low cytotoxicity, positive magnetic resonance (MR) contrast effect and better X-ray attenuation property than Iohexol, which enables effective dual-modality MR and X-ray computed tomography (CT) imaging of the tumor model in vivo. The enhanced near-infrared absorbance, good photothermal stability and efficient tumor passive targeting of GO/BaGdF5/PEG result in the highly efficient photothermal ablation of tumor in vivo after intravenous injection of GO/BaGdF5/PEG and the following 808-nm laser irradiation (0.5 W/cm(2)). The histological and biochemical analysis data reveal no perceptible toxicity of GO/BaGdF5/PEG in mice after treatment. These results indicate potential application of GO/BaGdF5/PEG in dual-modality MR/CT imaging and photothermal therapy of cancers.

  18. 10 kbar phase equilibria in the Y-Ba-Cu oxide system at 950 C

    SciTech Connect

    Lawanier, J.P.; Meen, J.K.; Elthon, D.

    1996-02-01

    Phase equilibria in the YO{sub 1.5}BaO-CuO system have been determined at 950 C at 10 kbar using a piston-cylinder apparatus. The oxide phases stable under these conditions are Y{sub 2}O{sub 3}, Y{sub 2}Cu{sub 2}O{sub 5}, CuO, Y{sub 2}BaCuO{sub 5}, YBa{sub 2}Cu{sub 3}O{sub 6.5}, BaCuO{sub 2}, Y{sub 2}BaO{sub 4}, Y{sub 2}Ba{sub 3}O{sub 6}, and YBa{sub 4}Cu{sub 2}O{sub 7.5}. The phase stabilities observed at 950 C at 10 kbar are identical to those observed at 950 C in air or oxygen at 1 atm for compositions with < 40% Ba of the cations. In more Ba-rich portions of the phase diagram, carbonates and oxycarbonates are stabilized and a systematic determination of the phase equilibria has not been successful.

  19. Mitochondrial decay is involved in BaP-induced cervical damage.

    PubMed

    Gao, Meili; Long, Jiangang; Li, Yongfei; Shah, Walayat; Fu, Ling; Liu, Jiankang; Wang, Yili

    2010-12-01

    Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon and a potent inducer of carcinogenesis. Many studies have reported that the carcinogenic effects of BaP might be due to its intermediate metabolites and to reactive oxygen species (ROS) that cause oxidative damage to the cells. However, the mechanisms of BaP-induced oxidative damage in cervical tissue are still not clear. We studied these mechanisms in female ICR mice treated with BaP either orally or intraperitoneally by measuring (1) several general biomarkers of oxidative stress in serum, (2) mitochondrial function in the cervix, and (3) the morphology of mitochondria in cervical tissue. BaP treatment (1) significantly lowered levels of vitamins A, C, and E and of glutathione; (2) reduced activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione S-transferases; and (3) significantly increased lipid peroxidation levels. In addition, significant increases in the levels of superoxide anion, hydrogen peroxide, and hydroxyl radical were observed. These results were confirmed by morphological changes in mitochondria and by decreases in membrane potential levels and in succinate dehydrogenase and malate dehydrogenase activities. The changes in these biomarkers and mitochondrial damage were BaP-dose-dependent and eventually induced both cell apoptosis and necrosis in cervical tissue. As mitochondria are the major sites of ROS generation, these findings show that mitochondrial decay greatly contributes to BaP-induced cervical damage.

  20. Thermodynamic stability of radiogenic Ba in CsAlSi2O6 pollucite

    NASA Astrophysics Data System (ADS)

    Jaffe, John; van Ginhoven, Renée; Jiang, Weilin

    2013-03-01

    Pollucite, a zeolite-like nanoporous aluminosilicate structure with nominal composition CsAlSi2O6, has been suggested as a nuclear waste storage form for fission-product radioactive isotopes of cesium, especially 137Cs. One factor affecting the long-term stability of this waste form is the valence change associated with the beta decay that converts Cs into barium. We have used first-principles density functional total energy calculations to evaluate the thermodynamic stability of pollucite with Ba replacing Cs at regular lattice sites with respect to the precipitation of Ba, Cs or their oxides. We included small clusters of substitutional BaCs as well as localized complexes of BaCs with compensating electron donor defects, specifically Cs vacancies and interstitial oxygen. We conclude that Cs-Ba pollucite is thermodynamically stable against precipitation of Cs or its oxide, but that partial precipitation of Ba or BaO may be thermodynamically favored under some conditions. Even this change may be kinetically limited, however. Fuel Cycle Research and Development, U.S. Department of Energy Waste Form Campaign

  1. Thickness-dependent dielectric properties of nanoscale Pt/(Pb,Ba)ZrO 3/BaPbO 3 capacitors

    NASA Astrophysics Data System (ADS)

    Wu, Lin-Jung; Wu, Jenn-Ming

    2007-10-01

    Lead barium zirconate (PBZ) thin films on BaPbO 3(BPO)/Pt/Ti/SiO 2/Si substrates have been prepared by rf-magnetron sputtering at 500 °C. The orientation of PBZ film changes from random to (1 1 1)-prefer oriented when the thickness increases. The grain size increases with increasing PBZ thickness. The dielectric properties are greatly suppressed when the thickness of dielectrics decreases. The dielectric constant and tunability decrease from 536% and 49.1% to 205% and 22.7%, respectively, when the thickness of PBZ decreases from 323 to 62 nm. The origins of the collapsed dielectric behavior are discussed. The variation of dielectric properties with film thickness can be interpreted by (a) antiferroelectric layer at PBZ/BPO interface, (b) dead layer at Pt/PBZ interface, and (c) grain boundary dead layers.

  2. Effects of induced optical tunable and ferromagnetic behaviors of Ba doped nanocrystalline LaB6.

    PubMed

    Bao, Lihong; Qi, Xiaoping; Tana; Chao, Lumen; Tegus, O

    2016-07-28

    Multiple nanocrystalline rare-earth hexaborides La1-xBaxB6 have been synthesized via a single step solid-state reaction. The Ba doping effects on crystal structure, grain morphology, magnetic and optical absorption properties were investigated using XRD, FESEM, HRTEM, SQUID magnetometry and optical measurements. The results show that all the Ba-doped hexaborides crystallize in the CsCl-type single phase, indicating the Ba atoms occupied the lattice sites of LaB6. The optical absorption results indicate that the absorption valleys of LaB6 are red-shifted from 622 nm to 780 nm when the Ba doping content increases to x = 0.8. The first-principle calculation results reveal that Ba doping reduces the total kinetic energy of the electrons of LaB6, which lead to the absorption valleys moving toward a higher wavelength. Meanwhile, the band gap of BaB6 obtained from optical absorption is in good agreement with the theoretical calculation results. The magnetic measurements results showed that Ba doping lead to room-temperature ferromagnetism of LaB6 due to the different ionic radii of La(3+) and Ba(2+) causing intrinsic crystal defects, which is directly observed experimentally by HRTEM. This is the first time that we have found the tunable optical and ferromagnetic behavior of Ba doped nanocrystalline LaB6. Thus, nanocrystalline La1-xBaxB6, as multi-functional materials, should open up a new route to extend the optical and magnetic applications of LaB6 nanopowder. PMID:27362626

  3. Crystallization of BaF2-ZnF2-YbF3-ThF4 glass

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Doremus, Robert H.; Ko, Sen-Hou; Margraf, Tracey; Bansal, Narottam P.

    1988-01-01

    The phases and the rates of crystallization in a Ba-Zn-Yb-Th fluoride glass were studied using differential scanning calorimetry, XRD, and observational and chemical SEM analyses. The crystallizing phases that were identified included a BaYbTh fluoride, ZnF2, and YbF3. The BaYbTh fluoride crystallized first at about 450 C, and ZnF2, which was excluded from this phase, crystallized at its surfaces. At higher temperatures, the BaYbTh fluoride phase decomposed partially to BaThF6 and YbF3 phases.

  4. Possible octupole deformation in Cs and Ba nuclei from their differential radii

    SciTech Connect

    Sheline, R.K.; Jain, A.K.; Jain, K.

    1988-12-01

    The odd-even staggering of the differential radii of Fr and Ra and the Cs and Ba nuclei is compared. This staggering is inverted in the region of known octupole deformation in the Fr and Ra nuclei. The normal staggering is eliminated in the Cs nuclei and attenuated in the Ba nuclei for neutron numbers 85--88. This fact is used to suggest the possible existence of octupole deformation and its neutron number range in the Cs and Ba nuclear ground states.

  5. Inter-atomic force constants of BaF{sub 2} by diffuse neutron scattering measurement

    SciTech Connect

    Sakuma, Takashi Makhsun,; Sakai, Ryutaro; Xianglian; Takahashi, Haruyuki; Basar, Khairul; Igawa, Naoki; Danilkin, Sergey A.

    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.

  6. Ferroelectric switching induced magnetic anisotropy in Fe/BaTiO3 bilayers

    NASA Astrophysics Data System (ADS)

    Duan, Chun-Gang; Jaswal, S. S.; Tsymbal, E. Y.

    2007-03-01

    Ferromagnetic/ferroelectric heterostructures have recently attracted significantly interest due to their potential applications in multifunctional electronic devices. We have recently predicted a magnetoelectric effect at the Fe/BaTiO3 interface induced by ferroelectric polarization reversal [1]. In this report, calculations are being carried out on the magnetic anisotropy of Fe/BaTiO3 films. Preliminary results show that the ferroelectric switching of the BaTiO3 has appreciable effect on the magnetic anisotropy of magnetic Fe films. This should be of interest in multiferroic device applications. [1] Chun-gang Duan, S. S. Jaswal, E. Y. Tsymbal, Phys. Rev. Lett. 97, 047201 (2006).

  7. Hydrothermal processing of BaTiO{sub 3}/polymer films

    SciTech Connect

    Slamovich, E.B.; Aksay, I.A.

    1994-12-31

    Hydrothermally derived films of BaTiO{sub 3} were fabricated by reacting thin layers of titanium organometallic liquid precursors in aqueous solutions containing Ba(OH){sub 2} and having a high pH. Cubic submicron polycrystalline films of BaTiO{sub 3} (thickness {approx} 1 {mu}m) were formed at 70 C. Low concentrations of block copolymers of polybutadiene and polystyrene were incorporated into the liquid precursor to prevent precursor film cracking. Higher polymer concentrations allowed fabrication of polymer/ceramic composite films by virtue of the low temperature used in hydrothermal processing.

  8. BaSTI: An updated, advanced and VO-compliant database of stellar evolution predictions

    NASA Astrophysics Data System (ADS)

    Pietrinferni, A.; Molinaro, M.; Cassisi, S.; Pasian, F.; Salaris, M.; Pelusi, D.; Manzato, P.; Vuerli, C.

    2014-11-01

    Stellar evolution model databases, spanning a wide ranges of masses and initial chemical compositions, are nowadays a major tool to study Galactic and extragalactic stellar populations. We describe here the current status of the widely used BaSTI (A Bag of Stellar Tracks and Isochrones) database. We focus in particular on the efforts devoted to port BaSTI to a VO-compliant environment, the BaSTI Web portal that enables users to retrieve data tables and run a range of web tools to facilitate the theoretical analysis of observations, and planned future developments within the framework of the Italian Virtual Observatory project.

  9. Metrological activity determination of 133Ba by sum-peak absolute method

    NASA Astrophysics Data System (ADS)

    da Silva, R. L.; de Almeida, M. C. M.; Delgado, J. U.; Poledna, R.; Santos, A.; de Veras, E. V.; Rangel, J.; Trindade, O. L.

    2016-07-01

    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. 133Ba is used in research laboratories and on calibration of detectors for analysis in different work areas. Classical absolute methods don't calibrate 133Ba due to its complex decay scheme. The sum-peak method using gamma spectrometry with germanium detector standardizes 133Ba samples. Uncertainties lower than 1% to activity results were obtained.

  10. Effect of ferroelectricity on electron transport in Pt/BaTiO3/Pt tunnel junctions.

    PubMed

    Velev, J P; Duan, Chun-Gang; Belashchenko, K D; Jaswal, S S; Tsymbal, E Y

    2007-03-30

    Based on first-principles calculations, we demonstrate the impact of the electric polarization on electron transport in ferroelectric tunnel junctions (FTJs). Using a Pt/BaTiO3/Pt FTJ as a model system, we show that the polarization of the BaTiO3 barrier leads to a substantial drop in the tunneling conductance due to changes in the electronic structure driven by ferroelectric displacements. We find a sizable change in the transmission probability across the Pt/BaTiO3 interface with polarization reversal, a signature of the electroresistance effect. These results reveal exciting prospects that FTJs offer as resistive switches in nanoscale electronic devices. PMID:17501233

  11. Superconducting behaviors in (Y1 - xLax)Ba2Cu3Oy (0 <= x <= 1)

    NASA Astrophysics Data System (ADS)

    Okada, M.; Matsuoka, D.; Zou, H.; Homma, M.

    1988-11-01

    The superconducting behavior of (Y1-xLax)Ba2Cu3Oy compounds for 0≤x≤1 was studied. It was found that Tc decreased with increasing La content. (Y1-xLax)Ba2Cu3Oy for 0≤x≤0.4, fired at 1050 °C in air, shows onset temperatures above 90 K. Annealing (Y1-xLax)Ba2Cu3Oy at 300 °C in O2 enhanced the onset temperature above 70 K for all studied compositions (x=0-1), and altered the crystal structure from tetragonal to orthorhombic.

  12. Genomics-based high-resolution mapping of the BaMMV/BaYMV resistance gene rym11 in barley (Hordeum vulgare L.).

    PubMed

    Lüpken, Thomas; Stein, Nils; Perovic, Dragan; Habekuss, Antje; Krämer, Ilona; Hähnel, Urs; Steuernagel, Burkhard; Scholz, Uwe; Zhou, Rounan; Ariyadasa, Ruvini; Taudien, Stefan; Platzer, Matthias; Martis, Mihaela; Mayer, Klaus; Friedt, Wolfgang; Ordon, Frank

    2013-05-01

    Soil-borne barley yellow mosaic virus disease, caused by different strains of Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus (BaMMV), is one of the most important diseases of winter barley (Hordeum vulgare L.) in Europe and East Asia. The recessive resistance gene rym11 located in the centromeric region of chromosome 4HL is effective against all so far known strains of BaMMV and BaYMV in Germany. In order to isolate this gene, a high-resolution mapping population (10,204 meiotic events) has been constructed. F2 plants were screened with co-dominant flanking markers and segmental recombinant inbred lines (RILs) were tested for resistance to BaMMV under growth chamber and field conditions. Tightly linked markers were developed by exploiting (1) publicly available barley EST sequences, (2) employing barley synteny to rice, Brachypodium distachyon and sorghum and (3) using next-generation sequencing data of barley. Using this approach, the genetic interval was efficiently narrowed down from the initial 10.72 % recombination to 0.074 % recombination. A marker co-segregating with rym11 was developed providing the basis for gene isolation and efficient marker-assisted selection.

  13. Improving the superconducting properties of single grain Sm-Ba-Cu-O bulk superconductors fabricated in air by increased control of Sm/Ba substitution effects

    NASA Astrophysics Data System (ADS)

    Shi, Y.; Desmedt, M.; Durrell, J.; Dennis, A. R.; Cardwell, D. A.

    2013-09-01

    The extreme sensitivity of Sm/Ba at high temperature in air becomes an obstacle to the fabrication of SmBCO single grains that exhibit stable and reliable superconducting properties. In this research, the superconducting properties of SmBCO single grains fabricated by top seeded melt growth (TSMG) from different batches of commercial SmBa2Cu3O7-d (Sm-123) precursor powder using different processing atmospheres (air and 0.1% O2 in Ar), different processing methods (isothermal growth and continuous cooling) and different amounts of BaO2 content to suppress Sm/Ba substitution in air have been investigated in an attempt to understand fully the TSMG process for this system. As a result, based on extensive data, a novel and simple, low temperature post-annealing approach is proposed specifically to overcome the sensitivity of Tc to Sm/Ba substitution in order to simplify the fabrication of SmBCO and to increase its reliability with a view to the practical processing of these materials. Initial processing trials have been performed successfully to demonstrate the viability of the novel post-annealing process.

  14. The role of Area 10 (BA10) in human multitasking and in social cognition: a lesion study.

    PubMed

    Roca, María; Torralva, Teresa; Gleichgerrcht, Ezequiel; Woolgar, Alexandra; Thompson, Russell; Duncan, John; Manes, Facundo

    2011-11-01

    A role for rostral prefrontal cortex (BA10) has been proposed in multitasking, in particular, the selection and maintenance of higher order internal goals while other sub-goals are being performed. BA10 has also been implicated in the ability to infer someone else's feelings and thoughts, often referred to as theory of mind. While most of the data to support these views come from functional neuroimaging studies, lesion studies are scant. In the present study, we compared the performance of a group of frontal patients whose lesions involved BA10, a group of frontal patients whose lesions did not affect this area (nonBA10), and a group of healthy controls on tests requiring multitasking and complex theory of mind judgments. Only the group with lesions involving BA10 showed deficits on multitasking and theory of mind tasks when compared with control subjects. NonBA10 patients performed more poorly than controls on an executive function screening tool, particularly on measures of response inhibition and abstract reasoning, suggesting that theory of mind and multitasking deficits following lesions to BA10 cannot be explained by a general worsening of executive function. In addition, we searched for correlations between performance and volume of damage within different subregions of BA10. Significant correlations were found between multitasking performance and volume of damage in right lateral BA10, and between theory of mind and total BA10 lesion volume. These findings stress the potential pivotal role of BA10 in higher order cognitive functions.

  15. Uptake, metabolism and macromolecular binding of benzo(a)pyrene (BaP) metabolites in channel catfish

    SciTech Connect

    Elskus, A.A.; McElroy, A.E.

    1995-12-31

    Polynuclear aromatic hydrocarbons (PAH), such as BaP, are contaminants with demonstrated carcinogenicity, yet little is known about the fate of PAH metabolites in aquatic organisms. Some invertebrates actively metabolize BaP to hydroxylated and conjugated forms, becoming BaP metabolite-rich prey items for fish. The authors examined the fate of BaP metabolites acquired by fish through diet. Channel catfish, Ictaluruspunctatus, were fed a single dose (2.5 umoles/kg fish) of either {sup 3}H-parent BaP or individual {sup 3}H-BaP metabolites: 3-hydroxy, 9-hydroxy, 9-sulfate or 9-glucuronidated BaP. After 24 hrs fish were killed, and samples of intestinal mucosa, bile, liver and muscle immediately frozen at {minus}80 C. Mean (n = 3--5) percent of dose retained was lowest for conjugated BaP (3.7%), 2--4 times higher for hydroxylated BaP (8.9%), and 5 times higher for parent BaP (18.9%). Differences were also observed between the distributions of individual metabolites in tissues. Radioactivity derived from parent and hydroxylated BaP was several fold higher in intestinal mucosa and bile than in liver or muscle. In contrast, radioactivity derived from conjugated BaP metabolites was more evenly distributed between all four tissues. These data demonstrate that in fish (1) dietary BaP metabolites are absorbed by the intestine, and they or their metabolites are transported to and absorbed by major tissue reservoirs (liver, muscle), (2) conjugated metabolites are less readily absorbed and/or retained than parent or hydroxylated BaP, and (3) some differences in metabolic fate exist between metabolites from the same class. DNA, RNA and protein adducts, as well as metabolite profiles, are being determined in liver and intestine.

  16. Pressure dependence of electronic properties of BaI{sub 2}

    SciTech Connect

    Kumar, Pradeep; Vedeshwar, Agnikumar G.

    2015-08-28

    We present Density Functional Theoretical (DFT) calculations of the electronic properties of scintillator material BaI{sub 2} under pressure which were carried out using Perdew-Burke-Ernzerhof genralized gradient approximation. We found that BaI{sub 2} is a direct band gap material with band gap calculated as 3.35 eV. The pressure effect on BaI{sub 2} indicates a linear monotonously decreasing band gap and increasing valence band width with pressure. We have observed the shifting of band extrema from the Γ point with pressure. The pressure coefficient of band gap is found to be −0.047 eV/GPa. The interatomic ionicity factor of BaI{sub 2} is found to be 0.51. Trends in bonding and ionicity under pressure are also discussed.

  17. New Resonances and Meson Spectroscopy at BaBar and Belle

    SciTech Connect

    Poireau, Vincent; /Annecy, LAPP

    2007-06-06

    We present a short review on the recent progresses that have been made in meson spectroscopy. We discuss the experimental discoveries made at the BaBar and Belle experiments, as well as the possible interpretations of the new resonances.

  18. Yttrium enrichment and improved magnetic properties in partially melted Y-Ba-Cu-O materials

    NASA Technical Reports Server (NTRS)

    Alterescu, Sidney; Hojaji, Hamid; Barkatt, Aaron; Michael, Karen A.; Hu, Shouxiang

    1990-01-01

    The yttrium-rich compositions in the Y-Ba-Cu-O system were mapped out in a systematic manner to quantify their magnetic properties and to correlate them with the microstructure and phase composition as determined by scanning electron microscopy and X-ray diffraction analysis. It is found that the microstructure of Y-Ba-Cu-O compositions is a sensitive function of both their composition and processing conditions. Measurements of magnetic susceptibility and maximum (low-field) and remanent magnetization for the system Y:Ba:Cu = x:2:3 show highest values for x = 2. The corresponding structures involve numerous small crystals of Y2BaCuO5 (211) embedded in highly ordered assemblages of continous YBa2Cu3O(7-y) (123) layers.

  19. Ba{sub 2}TeO as an optoelectronic material: First-principles study

    SciTech Connect

    Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; Singh, David J.; Siegrist, Theo

    2015-05-21

    The band structure, optical, and defects properties of Ba{sub 2}TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba{sub 2}TeO crystallizes with tetragonal structure (space group P4/nmm) and with a 2.93 eV optical bandgap [Besara et al., J. Solid State Chem. 222, 60 (2015)]. We find relatively modest band masses for both electrons and holes suggesting applications. Optical properties show infrared-red absorption when doped. This could potentially be useful for combining wavelength filtering and transparent conducting functions. Furthermore, our defect calculations show that Ba{sub 2}TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneous formation of the donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.

  20. Hydrothermal synthesis and tunable luminescence of NaBaPO4:Eu2+/Tb3+ phosphors

    NASA Astrophysics Data System (ADS)

    Wei, Zhen; Guan, Jinyu; Song, Juanjuan; Xu, Yongchun

    2015-12-01

    NaBaPO4:Eu2+/Tb3+ phosphors were synthesized by the hydrothermal process. The phase structure of obtained samples was characterized by powder X-ray diffraction. The morphology and size were obtained by field emission scanning electron microscope. Under the excitation at 346 nm, NaBaPO4:Eu2+/Tb3+ phosphors exhibited the emission band originating from the 4f65d1 → 4f7 transitions of Eu2+ and the emission bands originating from the 5D4 → 7Fj transitions of Tb3+. The intensities and lifetimes of Eu2+ decrease with increasing Tb3+ concentrations. On the basis of luminescence properties of NaBaPO4:Eu2+/Tb3+ phosphors, we can conclude the energy transfer occurs between Eu2+ and Tb3+ in NaBaPO4 host.

  1. SAmBA: an interactive software for optimizing the design of biological macromolecules crystallization experiments.

    PubMed

    Audic, S; Lopez, F; Claverie, J M; Poirot, O; Abergel, C

    1997-10-01

    SAmBA is a new software for the design of minimal experimental protocols using the notion of orthogonal arrays of strength 2. The main application of SAmBA is the search of protein crystallization conditions. Given a user input defining the relevant effectors/variables (e.g., pH, temperature, salts) and states (e.g., pH: 5, 6, 7 and 8), this software proposes an optimal set of experiments in which all tested variables and the pairwise interactions between them are symmetrically sampled. No a priori restrictions on the number and range of experimental variables is imposed. SAmBA consists of two complementary programs, SAm and BA, using a simulated annealing approach and a backtracking algorithm, respectively. The software is freely available as C code or as an interactive JAVA applet at http:/(/)igs-server.cnrs-mrs.fr. PMID:9329089

  2. BaMBa: towards the integrated management of Brazilian marine environmental data

    PubMed Central

    Meirelles, Pedro Milet; Gadelha, Luiz M. R.; Francini-Filho, Ronaldo Bastos; de Moura, Rodrigo Leão; Amado-Filho, Gilberto Menezes; Bastos, Alex Cardoso; Paranhos, Rodolfo Pinheiro da Rocha; Rezende, Carlos Eduardo; Swings, Jean; Siegle, Eduardo; Asp Neto, Nils Edvin; Leitão, Sigrid Neumann; Coutinho, Ricardo; Mattoso, Marta; Salomon, Paulo S.; Valle, Rogério A.B.; Pereira, Renato Crespo; Kruger, Ricardo Henrique; Thompson, Cristiane; Thompson, Fabiano L.

    2015-01-01

    A new open access database, Brazilian Marine Biodiversity (BaMBa) (https://marinebiodiversity.lncc.br), was developed in order to maintain large datasets from the Brazilian marine environment. Essentially, any environmental information can be added to BaMBa. Certified datasets obtained from integrated holistic studies, comprising physical–chemical parameters, -omics, microbiology, benthic and fish surveys can be deposited in the new database, enabling scientific, industrial and governmental policies and actions to be undertaken on marine resources. There is a significant number of databases, however BaMBa is the only integrated database resource both supported by a government initiative and exclusive for marine data. BaMBa is linked to the Information System on Brazilian Biodiversity (SiBBr, http://www.sibbr.gov.br/) and will offer opportunities for improved governance of marine resources and scientists’ integration. Database URL: http://marinebiodiversity.lncc.br PMID:26454874

  3. Synthesis, crystal structure, and photocatalytical properties of Ba3Ta5O14N

    NASA Astrophysics Data System (ADS)

    Anke, B.; Bredow, T.; Soldat, J.; Wark, M.; Lerch, M.

    2016-01-01

    Light yellow Ba3TaV5O14N was successfully synthesized as phase-pure material crystallizing isostructurally to well-known mixed-valence Ba3TaV4TaIVO15. The electronic structure of Ba3Ta5O14N was studied theoretically with a hybrid Hartree-Fock-DFT method. The most stable structure was obtained when nitrogen atoms were placed at 4 h sites having fourfold coordination. By incorporating nitrogen, the band gap decreases from ∼3.8 eV commonly known for barium tantalum(V) oxides to 2.8 eV for the oxide nitride, giving rise to an absorption band well in the visible-light region. Ba3Ta5O14N was also tested for photocatalytic hydrogen formation.

  4. Electronic structures and optical spectra of BaO from first principles

    SciTech Connect

    Wu, Chang-Wei; Pan, Bo; Wang, Neng-Ping

    2015-08-21

    We present the results of first-principles study for the electronic structure and optical absorption spectrum of the alkaline-earth metal oxide BaO. The quasiparticle band structure is evaluated within the Hedin's GW approximation [Phys. Rev. 139, A796 (1965)]. Thereafter, the electron-hole interaction is taken into consideration and the Bethe-Salpeter equation for the electron-hole two-particle Green function is solved. The calculated quasiparticle band gap of BaO is 4.1 eV, which is in good agreement with the experimental result. The calculated optical absorption spectrum of BaO is also in agreement with the experimental data. In particular, the calculated excitation energy for the lowest exciton peak in the optical absorption spectrum of BaO reproduces very well the corresponding experimental result.

  5. The electronic structure of the high-symmetry perovskite iridate Ba2IrO4

    NASA Astrophysics Data System (ADS)

    Moser, S.; Moreschini, L.; Ebrahimi, A.; Dalla Piazza, B.; Isobe, M.; Okabe, H.; Akimitsu, J.; Mazurenko, V. V.; Kim, K. S.; Bostwick, A.; Rotenberg, E.; Chang, J.; Rønnow, H. M.; Grioni, M.

    2014-01-01

    We report angle-resolved photoemission (ARPES) measurements, density functional and model tight-binding calculations on Ba2IrO4 (Ba-214), an antiferromagnetic (TN = 230 K) insulator. Ba-214 does not exhibit the rotational distortion of the IrO6 octahedra that is present in its sister compound Sr2IrO4 (Sr-214), and is therefore an attractive reference material to study the electronic structure of layered iridates. We find that the band structures of Ba-214 and Sr-214 are qualitatively similar, hinting at the predominant role of the spin-orbit interaction in these materials. Temperature-dependent ARPES data show that the energy gap persists well above TN, and favor a Mott over a Slater scenario for this compound.

  6. Consequences of Ca multisite occupation for the conducting properties of BaTiO3

    NASA Astrophysics Data System (ADS)

    Zulueta, Y. A.; Dawson, J. A.; Leyet, Y.; Anglada-Rivera, J.; Guerrero, F.; Silva, R. S.; Nguyen, Minh Tho

    2016-11-01

    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 BaTiO3. Simulation results for Ca solution energies in the BaTiO3 lattice show that the new oxygen vacancy inducing mixed mode exhibits low defect energies. A reduction in dc conductivity compared with undoped BaTiO3 is witnessed for the incorporation of Ca. The conducting properties of 5 mol% Ca-doped BaTiO3 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.

  7. Preparation and Luminescence Properties of Eu2+-ACTIVATED Ba-Six-O-N Phosphors

    NASA Astrophysics Data System (ADS)

    Zhang, Ruili; Numata, Manaka; Maeda, Tomonori; Akazawa, Yuji; Murai, Kei-Ichiro; Moriga, Toshihiro

    A series of oxonitridosilicates phosphors Ba-Six-O-N /Eu2+ (x=Si/Ba=1~8, 5atom% Eu2+) were synthesized using traditional solid-state reaction. For x = 2~8, the main phase of the obtained samples was Ba3Si6O12N2. All Ba-Six-O-N /Eu2+ (x = 1~8) materials could be efficiently excited in the UV to visible region(310~450nm) and had a green emission at 508~522nm, making them attractive as conversion phosphors for white LED applications. With increasing x values, the emission peaks shifted to the longer wavelength region, while the emission intensity had a maximum at x = 6. The influence of the firing times was also discussed, after twice fired, there was a tendency of single-phased formed of the obtained materials and the emission intensity was greatly improved.

  8. Ba2TeO as an optoelectronic material: First-principles study

    SciTech Connect

    Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; Siegrist, Theo; Singh, David J.

    2015-05-21

    The band structure, optical and defects properties of Ba2TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba2TeO crystallizes with tetragonal structure (space group P4/nmm) and with a 2.93 eV optical band gap1. We find relatively modest band masses for both electrons and holes suggesting applications. Optical properties show a infrared-red absorption when doped. This could potentially be useful for combining wavelength filtering and transparent conducting functions. Furthermore, our defect calculations show that Ba2TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneous formation of the donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.

  9. Deviations from soft mode behaviour in the Raman spectrum of incommensurate BaMnF 4

    NASA Astrophysics Data System (ADS)

    Murray, A. F.; Brims, G.; Sprunt, S.

    1981-09-01

    New measurements of the Raman spectrum of incommensurate BaMnF 4 reveal that there is not a classically 'soft' amplitude mode as has hitherto been assumed. This finding questions the validity of predictions based on straightforward Landau theory.

  10. Ba2TeO as an optoelectronic material: First-principles study

    DOE PAGES

    Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; Siegrist, Theo; Singh, David J.

    2015-05-21

    The band structure, optical and defects properties of Ba2TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba2TeO crystallizes with tetragonal structure (space group P4/nmm) and with a 2.93 eV optical band gap1. We find relatively modest band masses for both electrons and holes suggesting applications. Optical properties show a infrared-red absorption when doped. This could potentially be useful for combining wavelength filtering and transparent conducting functions. Furthermore, our defect calculations show that Ba2TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneous formation of themore » donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.« less

  11. Order-disorder transition in clathrate Ba6Ge25 studied by positron annihilation

    NASA Astrophysics Data System (ADS)

    Li, X. F.; Zhao, B.; Zhang, T.; He, H. F.; Zhang, Q.; Yang, D. W.; Chen, Z. Q.; Tang, X. F.

    2015-07-01

    Clathrate Ba6Ge25 is prepared by melt method and spark plasma sintering. Structural transition below room temperature is studied by positron annihilation and X-ray diffraction measurements. There is a pronounced transition in the temperature range of 200-250 K which might be involved with the movement of Ba atoms in Ge cages and result in disordered structure. This transition is further confirmed by the theoretical calculation of positron annihilation states. Thus our results confirm the structural models proposed by Carrillo-Cabrera et al. (2005). The measured specific heat capacity, electric resistivity and magnetic susceptibility all show anomalous transition in the same temperature range, indicating that the movement of Ba atoms in the cage has influence on the thermal, electric as well as magnetic properties of Ba6Ge25.

  12. Pregnane X receptor protects HepG2 cells from BaP-induced DNA damage.

    PubMed

    Naspinski, Christine; Gu, Xinsheng; Zhou, Guo-Dong; Mertens-Talcott, Susanne U; Donnelly, Kirby C; Tian, Yanan

    2008-07-01

    Pregnane X receptor (PXR) is a nuclear receptor that coordinately regulates transcriptional expression of both phase I and phase II metabolizing enzymes. PXR plays an important role in the pharmacokinetics of a broad spectrum of endogenous and xenobiotic compounds and appears to have evolved in part to protect organisms from toxic xenobiotics. Metabolism of benzo[a]pyrene (BaP), a well-established carcinogen and ubiquitous environmental contaminant, can result in either detoxification or bioactivation to its genotoxic forms. Therefore, PXR could modulate the genotoxicity of BaP by changing the balance of the metabolic pathways in favor of BaP detoxification. To examine the role of PXR in BaP genotoxicity, BaP-DNA adduct formation was measured by 32P-postlabeling in BaP-treated parental HepG2 cells and human PXR-transfected HepG2 cells. The presence of transfected PXR significantly reduced the level of adducts relative to parental cells by 50-65% (p < 0.001), demonstrating that PXR protects liver cells from genotoxicity induced by exposure to BaP. To analyze potential PXR-regulated detoxification pathways in liver cells, a panel of genes involved in phase I and phase II metabolism and excretion was surveyed with real-time quantitative reverse transcription PCR. The messenger RNA levels of CYP1A2, GSTA1, GSTA2, GSTM1, UGT1A6, and BCRP (ABCG2) were significantly higher in cells overexpressing PXR, independent of exposure to BaP. In addition, the total GST enzymatic activity, which favors the metabolic detoxification of BaP, was significantly increased by the presence of PXR (p < 0.001), independent of BaP exposure. Taken together, these results suggest that PXR plays an important role in protection against DNA damage by polycyclic aromatic hydrocarbons (PAHs) such as BaP, and that these protective effects may be through a coordinated regulation of genes involved in xenobiotic metabolism.

  13. Barium aluminides Ba{sub x}Al{sub 5}(x=3,3.5,4)

    SciTech Connect

    Jehle, Michael; Scherer, Harald; Wendorff, Marco; Roehr, Caroline

    2009-05-15

    Three aluminides of the series Ba{sub x}Al{sub 5}(x=3,3.5,4) were synthesized from stoichiometric ratios of the elements in Ta crucibles. The crystal structure of the new compound Ba{sub 7}Al{sub 10} was determined using single crystal X-ray data (space group R3-barm, a=604.23(9), c=4879.0(12)pm, Z=3, R1=0.0325). The compound exhibits Al Kagome (3.6.3.6.) nets in which half of the triangles form the basis of trigonal bipyramids Al{sub 5}. The apical Al are thus three-bonded assuming a charge of -2 ({sup 27}Al-NMR chemical shift delta=660pm), whereas the Al atoms of the basal triangle (i.e. of the Kagome net) are four-bonded and thus of formal charge -1(delta=490ppm). The total charge of the anion is thus exactly compensated by the Ba cations, i.e. the compound can be interpreted as an electron precise Zintl phase, exhibiting a distinct pseudo-band gap at the Fermi level of the calculated tDOS. According to the total formula, the structure displays a combination the stacking sequences of Ba{sub 3}Al{sub 5} and Ba{sub 4}Al{sub 5}, the structures of which have been redetermined with current methods (both hexagonal with space group P6{sub 3}/mmc; Ba{sub 3}Al{sub 5}: a=606.55(7), c=1461.8(2)pm, Z=2, R1=0.0239; Ba{sub 4}Al{sub 5}: a=609.21(7), c=1775.8(3)pm, Z=2, R1=0.0300). These three compounds with slightly different electron counts but similar polyanions allow to compare the bond lengths, the electronic structures and the overall bonding situation in dependence of positive or negative deviation of the electron count in relation to the novel formally electron precise Zintl compound Ba{sub 7}Al{sub 10}. - Al{sub 5} layers of Kagome nets in the new binary electron precise Zintl compound Ba{sub 3.5}Al{sub 5}, also found in Ba{sub 3}Al{sub 5} and Ba{sub 4}Al{sub 5}.

  14. NO2 uptake under practically relevant conditions on BaO/Pt(111)

    SciTech Connect

    Mudiyanselage, Kumudu; Szanyi, János

    2012-02-01

    The formation of nitrites and nitrates (Ba(NOx)2) under practically relevant conditions (PNO2 up to 1.0 Torr and T = 500 K) and their thermal decomposition on BaO (>20 monolayer equivalent (MLE))/Pt(1 1 1) were studied using temperature programmed desorption (TPD), infrared reflection absorption (IRA), and Xray photoelectron (XP) spectroscopies. The exposure of BaO to 1.0 × 10-8 Torr NO2 at 500 K leads to the formation of a Ba(NOx)2 layer with small, disordered crystalline nitrate clusters. Under these conditions (PNO2 = 1.0 × 10-8 Torr and T = 500 K) only the top portion of the BaO layer converts to Ba(NOx)2 and the nitrites in this Ba(NOx)2 layer stay without converting completely to nitrates even after 100 min of NO2 exposure. In the thermal decomposition of Ba(NOx)2, first nitrites decompose, releasing NO and then the decomposition of nitrates occurs via two pathways releasing NO2 and NO + O2. At 500 K and PNO2 ≥ 1.0 × 10-7 Torr, first NO2 reacts with BaO to form small disordered crystalline Ba(NO3)2 particles and then these particles agglomerate to form large, well-ordered (bulk-like) crystalline nitrates as the NO2 exposure increases. The thermal decomposition of these well-ordered, bulk-like crystalline nitrate aggregates occurs in two steps releasing NO2 and NO + O2 in each step in two different temperature regions. NO2 pressure ≥1.0 × 10-5 Torr is required for the complete oxidation of initially formed nitrites to nitrates and the full nitration of the BaO layer at 500 K sample temperature. We gratefully acknowledge the US Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by

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

    NASA Astrophysics Data System (ADS)

    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).

  16. Radioluminescence as a function of temperature and low temperature thermoluminescence of BaY2F8:Ce and BaY2F8:Nd crystals

    NASA Astrophysics Data System (ADS)

    Kowalski, Z.; Kaczmarek, S. M.; Brylew, K.; Drozdowski, W.

    2016-09-01

    Radioluminescence spectra at temperatures ranging from 10 to 320 K and low temperature thermoluminescence glow curves of BaY2F8:Ce and BaY2F8:Nd scintillator crystals have been investigated. In both materials the intensities of the excitonic and the activator ion's emission at X-ray excitation vary with temperature, anticorrelating with each other, which provides valuable information on the host-to-ion energy transfer. Detailed thermoluminescence studies, in turn, prove the existence of charge traps, which introduce quasi-continuous distributions of energy levels into the bandgap.

  17. Photoluminescence and long after glow in Ba2MgSi2O7: Eu2+ and Ba2ZnSi2O7: Eu2+ phosphors

    NASA Astrophysics Data System (ADS)

    Talwar, Gurjeet J.; Moharil, S. V.; Joshi, C. P.

    2016-05-01

    Silicate phosphors doped with Eu2+ find application in solid state lighting, plasma display panel, liquid crystal display and long after glow. In present work long lasting silicate phosphors are prepared by a modified combustion synthesis. The photoluminescence spectra and long lasting decay curves are measured. The Emission wavelength of Ba2MgSi2O7: Eu2+ is observed at 500 nm for excitation 345 nm.The emission wavelength of Ba2ZnSi2O7: Eu2+ is obtained at 496 nm at excitation 350 nm. Decay constants are calculated for both the phosphors.

  18. Effect of conductive BaPbO3 electrode on the structural and dielectric properties of (Pb,Ba)ZrO3 films

    NASA Astrophysics Data System (ADS)

    Wu, Lin-Jung; Wu, Jenn-Ming

    2007-08-01

    Highly (1 1 1)-oriented (Pb,Ba)ZrO3 (PBZ) thin films were deposited on BaPbO3(BPO) electrode at different deposition temperatures and different thicknesses. As the deposition temperature increased, the dielectric constant and tunability increased from 150 and 4% to 500 and 56%, respectively. A current transient peak observed prior to dielectric degradation can be related to oxygen vacancy migration (redistribution) with space-charge-limited current transient or modulation of the electric conductivity. We infer that an interfacial layer lying between the PBZ and BPO effectively increases the oxygen vacancy (density ~1020 cm-3) mobility by Pb4+ diffusing into the PBZ films.

  19. Ba/Ca Reproducibility and Growth Banding in Gulf of Alaska Bamboo Corals

    NASA Astrophysics Data System (ADS)

    Serrato Marks, G.; LaVigne, M.; Hill, T. M.; Sauthoff, W.; Guilderson, T. P.; Roark, E. B.; Dunbar, R. B.

    2014-12-01

    Deep-sea bamboo corals have been proposed as deep-ocean paleoceanographic archives because of their longevity and radial growth bands. Previous work has shown that bamboo coral Ba/Ca is a promising proxy for seawater barium, however, validation of Ba/Ca reproducibility is required. In addition, the growth band formation mechanism is uncertain, with some proposing that crystal orientation causes banding visible under light microscopy. The objective of this study was to evaluate Ba/Ca reproducibility and characterize growth band crystal orientation. Visible bands measured with a petrographic microscope were used to align LA-ICP-MS data collected along three replicate radii of the calcitic internodes of two well-dated corals from the Gulf of Alaska (collected live at 720m and 643m; 48°3'N, 132°44'W). Ba/Ca signals smoothed to ~annual resolution were reproducible within each coral (r=0.6-0.7; p<0.0001; n=3 radii/coral), suggesting that Ba/Ca varies in response to the external environment on annual timescales. Ba/Ca in the 720m coral increased from 1977 to 1998, a warm Pacific Decadal Oscillation (PDO) regime, possibly due to increased export production. The shallower coral (634m) revealed the inverse trend, suggesting variability in seawater barium dynamics with depth. Electron backscatter diffraction analysis of visible growth bands showed a preferred crystal orientation that does not correspond to location of visible bands or elemental composition, suggesting that crystal orientation does not cause bamboo coral banding. Overall, results show that regional oceanic signals are recorded as reproducible Ba/Ca variability in these corals. Comparison of these data to other well-dated records from the northeast Pacific would determine whether the relationship between Ba/Ca and PDO is regional. Additional archives of trace element variability will strengthen our understanding of how rapid climate change impacts intermediate ocean biogeochemistry.

  20. Synthesis and photoactivity enhancement of Ba doped Bi{sub 2}WO{sub 6} photocatalyst

    SciTech Connect

    Li, Wen Ting; Huang, Wan Zhen; Zhou, Huan; Yin, Hao Yong; Zheng, Yi Fan; Song, Xu Chun

    2015-04-15

    Highlights: • The Ba-doped Bi{sub 2}WO{sub 6} photocatalyst have been synthesized by a hydrothermal route. • The photocatalytic activity of Bi{sub 2}WO{sub 6} was greatly enhanced by Ba-doping. • The effect of Ba on the catalytic activity of Bi{sub 2}WO{sub 6} was studied and discussed. - Abstract: In this study, Bi{sub 2}WO{sub 6} doped with different barium contents were successfully prepared by a simple hydrothermal route at 180 °C for 12 h. The as-synthesized samples were characterized in detailed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffusere flectance spectroscopy (UV–vis DRS) and Brunauer–Emmet–Teller (BET) theory. Their photocatalytic activities were evaluated by photodegradation of Rhodamine B (RhB) under simulated solar light. As a result, the photocatalytic properties were enhanced after Ba doping and the Ba-doped Bi{sub 2}WO{sub 6} with R{sub Ba} = 0.15 showed the highest photocatalytic activities of 96.3% RhB was decomposed in 50 min. Close investigation revealed that the proper Ba doped into Bi{sub 2}WO{sub 6} could not only increases its BET surface area, decrease its crystalline size, but also act as electron traps and facilitate the separation of photogenerated electron–hole pairs. The mechanism of enhanced photocatalytic activities of Ba-doped Bi{sub 2}WO{sub 6} were further investigated.

  1. Resistance to micro-plastic deformation in superconducting Y-Ba-Cu-O

    NASA Astrophysics Data System (ADS)

    Nishi, Yoshitake; Tokunaga, Shigeki; Toyama, Toshinobu

    1988-01-01

    The stress-strain behavior of a Y-Ba-Cu-O superconducting ceramic (Tc above 90 K) is investigated experimentally under conditions of microplastic deformation using X-ray diffraction analysis and Vickers hardness measurements. The resistance of YBa2Cu3O(9-y) specimens to microplastic deformation is estimated at HV 520 at the surface and 300 in the bulk. It is further shown that polishing increases Tc by removing a surface layer of sintered Y-Ba-Cu oxide.

  2. Evidence for superconductivity above 40 K in the La-Ba-Cu-O compound system

    NASA Technical Reports Server (NTRS)

    Chu, C. W.; Hor, P. H.; Meng, R. L.; Gao, L.; Huang, Z. J.

    1987-01-01

    An apparent superconducting transition with an onset temperature above 40 K has been detected under pressure in the La-Ba-Cu-O compound system synthesized directly from a solid-state reaction of La2O3, CuO, and BaCO3 followed by a decomposition of the mixture in a reduced atmosphere. The experiment is described and the results of effects of magnetic field and pressure are discussed.

  3. Superconductivity in the Sn-Ba-Sr-Y-Cu-O system

    NASA Technical Reports Server (NTRS)

    Aleksandrov, K. S.; Khrustalev, B. P.; Krivomazov, S. N.; Petrov, M. I.; Vasilyev, A. D.; Zwegintsev, S. A.

    1991-01-01

    After the discovery of high-T(sub c) superconductivity in the La-Ba-Cu-O compound, several families of superconducting oxides were synthesized. Here, researchers report the results of the search for superconductivity in the compounds based on tin which has a lone electron pair like Bi, Tl, and Pb. The following compounds were synthesized: Sn1Ba1Sr1Cu3O(sub x), Sn1Ba1Ca1Cu3O(sub x), Sn1Ba1Mg1Cu3O(sub x), Sn1Sr1Ca1Cu3O(sub x), Sn1Sr1Mg1Cu3O(sub x), and Sn1Ca1Mg1Cu3O(sub x). The initial components were oxides and carbonates of the appropriate elements. A standard firing-grinding procedure was used. Final heating was carried out at 960 C during 12 hours. Then the samples were cooled inside the furnace. All the synthesis cycles were carried out in air atmosphere. Among the synthesized compounds only Sn1Ba1Sr1Cu3O(sub x) showed remarkable conductivity. Other compounds were practically dielectrics. Presence of a possible superconductivity in Sn1Ba1Sr1Cu3O(sub x) was defined by using the Meissner effect. At low temperature a deviation from paramagnetic behavior is observed. The hysteresis loops obtained at lower temperature undoubtly testify to the presence of a superconductive phase in the sample. However, the part of the superconductive phase in the Sn1Ba1Sr1Cu3O(sub x) ceramic turned out to be small, less than 2 percent, which agrees with the estimation from magnetic data. In order to increase the content of the superconductive phase, two-valent cations Ba and Sr were partially substituted by univalent (K) and three-valent ones (Y).

  4. Superconductivity in the Sn-Ba-Sr-Y-Cu-O system

    NASA Technical Reports Server (NTRS)

    Aleksandrov, K. S.; Khrustalev, B. P.; Krivomazov, S. N.; Petrov, M. I.; Vasilyev, A. D.; Zwegintsev, S. A.

    1990-01-01

    Since Bednorz and Muller discovered high-T(sub c) superconductivity in the La-Ba-Cu-O compound, several families of superconducting oxides have been synthesized. Here, researchers report the results of search for superconductivity in the compounds based on tin, which has a lone electron pair like Bi, Tl, Pb. The following compounds were synthesized: Sn1Ba1Sr1Cu3Ox, Sn1Ba1Ca1Cu3Ox, Sn1Ba1Mg1Cu3Ox, Sn1Sr1Ca1Cu3Ox, Sn1Sr1Mg1Cu3Ox, Sn1Ca1Mg1Cu3Ox. The initial components were oxides and carbonates of the appropriate elements. Standard firing-grinding procedure was used. Final heating was carried out at 960 C during 12 hours. Then the samples were cooled inside the furnace. All the synthesis cycles were carried out in air atmosphere. Among the synthesized compounds only Sn1Ba1Sr1Cu3Ox showed remarkable conductivity. Other compounds were practically dielectrics. Presence of a possible superconductivity in Sn1Ba1Sr1Cu3Ox was defined by using the Meissner effect. At low temperature a deviation from paramagnetic behavior is observed. The hysteresis loops obtained at lower temperatures undoubtly testify to the presence of a superconductive phase in the sample. However, the part of the superconductive phase in the Sn1Ba1Sr1Cu3Ox ceramic turned out to be small, less than 2 percent, which agrees with the estimation from magnetic data. In order to increase the content of the superconductive phase two-valent cations Ba, Sr were partially substituted by univalent (K) and three-valent ones (Y).

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Picosecond Nd:BaY2F8 laser discretely tunable around 1 μm

    NASA Astrophysics Data System (ADS)

    Agnesi, A.; Pirzio, F.; Reali, G.; Toncelli, A.; Tonelli, M.

    2010-09-01

    Passive mode-locking of a diode-pumped Nd:BaY2F8 (Nd:BaYF) was achieved on four lines in the range 1040-1074 nm, employing a semiconductor saturable absorber mirror (SAM). Nearly Fourier-limited pulses with durations of 2.6 to 7.2 ps and output power ≈50 mW were generated in a dispersion-controlled resonator using a single prism for wavelength selection, tuning and dispersion management.

  7. Plastic debris ingestion by sea turtle in Paraíba, Brazil.

    PubMed

    Mascarenhas, Rita; Santos, Robson; Zeppelini, Douglas

    2004-08-01

    Coastal gill net entanglement and debris intake are important threats to the survival of sea turtles. Two sea turtles (Lepidochelys olivacea and Chelonia mydas) were found stranded along the coast of Paraíba. After necropsy, plastic debris were found in the stomach. The debris is described. This is the first record of this sort of problem for the Paraíba littoral.

  8. Expected production of new exotic α emitters 108Xe and 112Ba in complete fusion reactions

    NASA Astrophysics Data System (ADS)

    Kalandarov, Sh. A.; Adamian, G. G.; Antonenko, N. V.; Wieleczko, J. P.

    2016-05-01

    The production cross sections of neutron-deficient isotopes Xe-110108 and Ba-114112 in the complete fusion reactions Ni,5658+54Fe and Ni,5658+58Ni with stable and radioactive beams are studied with the dinuclear system model. The calculated results are compared with the available experimental data. The optimal beam energies and corresponding maximum production cross sections of new isotopes 108Xe and 112Ba are predicted.

  9. Superconductivity in the Sn-Ba-Sr-Y-Cu-O system

    NASA Astrophysics Data System (ADS)

    Aleksandrov, K. S.; Khrustalev, B. P.; Krivomazov, S. N.; Petrov, M. I.; Vasilyev, A. D.; Zwegintsev, S. A.

    1990-04-01

    Since Bednorz and Muller discovered high-T(sub c) superconductivity in the La-Ba-Cu-O compound, several families of superconducting oxides have been synthesized. Here, researchers report the results of search for superconductivity in the compounds based on tin, which has a lone electron pair like Bi, Tl, Pb. The following compounds were synthesized: Sn1Ba1Sr1Cu3Ox, Sn1Ba1Ca1Cu3Ox, Sn1Ba1Mg1Cu3Ox, Sn1Sr1Ca1Cu3Ox, Sn1Sr1Mg1Cu3Ox, Sn1Ca1Mg1Cu3Ox. The initial components were oxides and carbonates of the appropriate elements. Standard firing-grinding procedure was used. Final heating was carried out at 960 C during 12 hours. Then the samples were cooled inside the furnace. All the synthesis cycles were carried out in air atmosphere. Among the synthesized compounds only Sn1Ba1Sr1Cu3Ox showed remarkable conductivity. Other compounds were practically dielectrics. Presence of a possible superconductivity in Sn1Ba1Sr1Cu3Ox was defined by using the Meissner effect. At low temperature a deviation from paramagnetic behavior is observed. The hysteresis loops obtained at lower temperatures undoubtly testify to the presence of a superconductive phase in the sample. However, the part of the superconductive phase in the Sn1Ba1Sr1Cu3Ox ceramic turned out to be small, less than 2 percent, which agrees with the estimation from magnetic data. In order to increase the content of the superconductive phase two-valent cations Ba, Sr were partially substituted by univalent (K) and three-valent ones (Y).

  10. Crystallography and Physical Properties of BaCo2As2, Ba0.94K0.06Co2As2, and Ba0.78K0.22Co2As2

    SciTech Connect

    Anand, V K; Quirinale, Dante G; Lee, Yongbin; Harmon, Bruce N; Furukawa, Yuji; Ogloblichev, V V; Huq, A; Abernathy, D L; Stephens, P W; McQueeney, Robert J; Kreyssig, Aandreas; Goldman, Alan I; Johnston, David C

    2014-08-01

    The crystallographic and physical properties of polycrystalline and single crystal samples of BaCo2As2 and K-doped Ba{1-x}K{x}Co2As2 (x = 0.06, 0.22) are investigated by x-ray and neutron powder diffraction, magnetic susceptibility chi, magnetization, heat capacity Cp, {75}As NMR and electrical resistivity rho measurements versus temperature T. The crystals were grown using both Sn flux and CoAs self-flux, where the Sn-grown crystals contain 1.6-2.0 mol% Sn. All samples crystallize in the tetragonal ThCr2Si2-type structure (space group I4/mmm). For BaCo2As2, powder neutron diffraction data show that the c-axis lattice parameter exhibits anomalous negative thermal expansion from 10 to 300 K, whereas the a-axis lattice parameter and the unit cell volume show normal positive thermal expansion over this T range. No transitions in BaCo2As2 were found in this T range from any of the measurements. Below 40-50 K, we find rho ~ T^2 indicating a Fermi liquid ground state. A large density of states at the Fermi energy D(EF) ~ 18 states/(eV f.u.) for both spin directions is found from low-T Cp(T) measurements, whereas the band structure calculations give D(EF) = 8.23 states/(eV f.u.). The {75}As NMR shift data versus T have the same T dependence as the chi(T) data, demonstrating that the derived chi(T) data are intrinsic. The observed {75}As nuclear spin dynamics are consistent with the presence of ferromagnetic and/or stripe-type antiferromagnetic spin fluctuations. The crystals of Ba{0.78}K{0.22}Co2As2 were grown in Sn flux and show properties very similar to those of undoped BaCo2As2. On the other hand, the crystals from two batches of Ba{0.94}K{0.06}Co2As2 grown in CoAs self-flux show evidence of weak ferromagnetism at T < 10 K with small ordered moments at 1.8 K of 0.007 and 0.03 muB per formula unit, respectively.

  11. Measurements of the CKM Angle Alpha at BaBar

    SciTech Connect

    Stracka, Simone; /Milan U. /INFN, Milan

    2012-04-04

    The authors present improved measurements of the branching fractions and CP-asymmetries fin the B{sup 0} {yields} {pi}{sup +}{pi}{sup -}, B{sup 0} {yields} {pi}{sup 0}{pi}{sup 0}, and B{sup +} {yields} {rho}{sup +}{rho}{sup 0} decays, which impact the determination of {alpha}. The combined branching fractions of B {yields} K{sub 1}(1270){pi} and B {yields} K{sub 1}(1400){pi} decays are measured for the first time and allow a novel determination of {alpha} in the B{sup 0} {yields} {alpha}{sub 1}(1260){sup {+-}}{pi}{sup {-+}} decay channel. These measurements are performed using the final dataset collected by the BaBar detector at the PEP-II B-factory. The primary goal of the experiments based at the B factories is to test the Cabibbo-Kobayashi-Maskawa (CKM) picture of CP violation in the standard model of electroweak interactions. This can be achieved by measuring the angles and sides of the Unitarity Triangle in a redundant way.

  12. Redetermination of β-Ba(PO3)2

    PubMed Central

    Weil, Matthias

    2014-01-01

    In comparison with the previous structure determination of the β-modification of barium catena-polyphosphate that was based on Weissenberg film data [Grenier et al. (1967 ▶). Bull. Soc. Fr. Minéral. Cristallogr. 90, 24–31], the current CCD-data-based redetermination reveals all atoms with anisotropic displacement parameters, standard uncertainties for the atomic coordinates, and the determination of the absolute structure. Moreover, a much higher accuracy in terms of the bond-length distribution for the polyphosphate chain, with two shorter and two longer P—O distances, was achieved. The structure consists of polyphosphate chains extending parallel to [100] with a periodicity of two PO4 tetra­hedra. The Ba2+ cations are located between the chains and are surrounded by ten O atoms in the form of a distorted coordination polyhedron, with Ba—O distances ranging from 2.765 (3) to 3.143 (3) Å, also reflecting the higher precision of the current redetermination. PMID:24764803

  13. The BaBar Gas Bubbler Upgrade and Evaluation

    SciTech Connect

    Gan, Yu; Young, C.; /SLAC

    2005-12-15

    The Instrumented Flux Return region (muon and K{sub L} detection barrel) of the BaBar detector at SLAC requires careful monitoring of the gas flow through the detector array. This is currently done by a system of digital gas bubblers which monitor the flow rate by using photogate technology to detect the presence of bubbles formed by gas flowing through an internal oil chamber. Recently, however, a design flaw was discovered in these bubblers. Because the bubblers are connected directly to the detector array with no filter, during rises in atmospheric pressure or a drop in the gas flow rate (e.g. when the gas system is shut off for maintenance), the oil in this chamber could be forced backwards into the detector tubes. To compensate for this problem, we upgraded the existing gas bubbler systems by installing metal traps into the old gas lines to capture the oil. This installation was followed by an evaluation of the retro-fitted bubblers during which we determined a relationship between the bubble counting rate and the actual gas flow rate, but encountered recurring problems with baseline fluctuations and unstable bubble counting rates. Future work will involve the study of how these instabilities develop, and whether or not they can be mitigated.

  14. 137 Ba Double Gamma Decay Measurement with GAMMASPHERE

    SciTech Connect

    Merchán, E.; Moran, K.; Lister, C. J.; Chowdhury, P.; McCutchan, E. A.; Greene, J. P.; Zhu, S.; Lauritsen, T.; Carpenter, M. P.; Shearman, R.

    2015-05-28

    The study of the electromagnetic moments (EM), and decay probability, provides detailed information about nuclear wave functions. The well-know properties of EM interactions are good for extracting information about the motion of nucleons. Higher order EM processes always occur, but are usually too weak to be measured. In the case of a 0+ → 0+ transitions, where a single gamma transition is forbidden, the simultaneous emission of two γ-rays has been studied. An interesting opportunity to further investigate 2-photon emission phenomena is by using a standard 137Cs source populating, via β-decay, the Jπ = 11/2- isomeric state at 662 keV in 137Ba. In this case, two photon process can have contributions from quadrupole-quadrupole or dipole-octupole multipolarities in direct competition with the high multipolarity M4 decay. Since the yield of the double gamma decay is around six orders of magnitude less than the first order transition, very good statistics are needed in order to observe the phenomena and great care must be taken to suppress the first-order decay. The Gammasphere array is ideal since its configuration allows a good coverage of the angular distribution and the Compton events can be suppressed. Nevertheless the process to understand and eliminate the Compton background is a challenge. Geant4 simulations were carried out to help understand and correct for those factors.

  15. The BaBar Data Reconstruction Control System

    SciTech Connect

    Ceseracciu, A

    2005-04-20

    The BaBar experiment is characterized by extremely high luminosity and very large volume of data produced and stored, with increasing computing requirements each year. To fulfill these requirements a Control System has been designed and developed for the offline distributed data reconstruction system. The control system described in this paper provides the performance and flexibility needed to manage a large number of small computing farms, and takes full benefit of OO design. The infrastructure is well isolated from the processing layer, it is generic and flexible, based on a light framework providing message passing and cooperative multitasking. The system is distributed in a hierarchical way: the top-level system is organized in farms, farms in services, and services in subservices or code modules. It provides a powerful Finite State Machine framework to describe custom processing models in a simple regular language. This paper describes the design and evolution of this control system, currently in use at SLAC and Padova on {approx}450 CPUs organized in 9 farms.

  16. 137 Ba Double Gamma Decay Measurement with GAMMASPHERE

    DOE PAGES

    Merchán, E.; Moran, K.; Lister, C. J.; Chowdhury, P.; McCutchan, E. A.; Greene, J. P.; Zhu, S.; Lauritsen, T.; Carpenter, M. P.; Shearman, R.

    2015-05-28

    The study of the electromagnetic moments (EM), and decay probability, provides detailed information about nuclear wave functions. The well-know properties of EM interactions are good for extracting information about the motion of nucleons. Higher order EM processes always occur, but are usually too weak to be measured. In the case of a 0+ → 0+ transitions, where a single gamma transition is forbidden, the simultaneous emission of two γ-rays has been studied. An interesting opportunity to further investigate 2-photon emission phenomena is by using a standard 137Cs source populating, via β-decay, the Jπ = 11/2- isomeric state at 662 keVmore » in 137Ba. In this case, two photon process can have contributions from quadrupole-quadrupole or dipole-octupole multipolarities in direct competition with the high multipolarity M4 decay. Since the yield of the double gamma decay is around six orders of magnitude less than the first order transition, very good statistics are needed in order to observe the phenomena and great care must be taken to suppress the first-order decay. The Gammasphere array is ideal since its configuration allows a good coverage of the angular distribution and the Compton events can be suppressed. Nevertheless the process to understand and eliminate the Compton background is a challenge. Geant4 simulations were carried out to help understand and correct for those factors.« less

  17. Mechanical properties of DyBaCuO superconducting bulks

    NASA Astrophysics Data System (ADS)

    Fujimoto, H.; Shimada, H.; Yoshizawa, S.

    2007-10-01

    Melt-processed REBaCuO (RE: rare earth) superconductors have a high Jc at 77 K and a high magnetic field, which are expected to be used for high field applications such as superconducting permanent magnets with liquid nitrogen refrigeration, flywheels, current leads and so on. Mechanical properties such as flexural strength, fracture toughness and ductility are very crucial as well as the superconducting properties: Tc, Jc, and Hirr for industrial applications of high-Tc oxide superconductors. However, oxide superconductors have the intrinsic brittleness of the perovskite structure, thus, the strength and the fracture toughness of REBaCuO superconductors have been reported to be low and anisotropic. Therefore, we should investigate and improve mechanical properties to achieve structural reliability for applications. Large single domain of melt-processed REBaCuO (Dy-123) superconductors with Dy2BaCuO5 (Dy-211) particles and Ag2O of 10 wt% was fabricated with a seeding and temperature gradient method in air. In this study, we discuss mechanical properties such as the hardness and the surface roughness, and the flexural strength of the RE-123 bulk, measured at RT. The results of Vickers hardness, surface roughness and the flexural strength showed very important information for evaluating characteristics of RE-123 bulks.

  18. Ferroelectric and ferromagnetic properties in BaTiO{sub 3} thin films on Si (100)

    SciTech Connect

    Singamaneni, Srinivasa Rao Prater, John T.; Punugupati, Sandhyarani; Hunte, Frank; Narayan, Jagdish

    2014-09-07

    In this paper, we report on the epitaxial integration of room temperature lead-free ferroelectric BaTiO{sub 3} thin (∼1050 nm) films on Si (100) substrates by pulsed laser deposition technique through a domain matching epitaxy paradigm. We employed MgO and TiN as buffer layers to create BaTiO{sub 3}/SrRuO{sub 3}/MgO/TiN/Si (100) heterostructures. C-axis oriented and cube-on-cube epitaxial BaTiO{sub 3} is formed on Si (100) as evidenced by the in-plane and out-of-plane x-ray diffraction, and transmission electron microscopy. X-ray photoemission spectroscopic measurements show that Ti is in 4(+) state. Polarization hysteresis measurements together with Raman spectroscopy and temperature-dependent x-ray diffraction confirm the room temperature ferroelectric nature of BaTiO{sub 3}. Furthermore, laser irradiation of BaTiO{sub 3} thin film is found to induce ferromagnetic-like behavior but affects adversely the ferroelectric characteristics. Laser irradiation induced ferromagnetic properties seem to originate from the creation of oxygen vacancies, whereas the pristine BaTiO{sub 3} shows diamagnetic behavior, as expected. This work has opened up the route for the integration of room temperature lead-free ferroelectric functional oxides on a silicon platform.

  19. Luminescence and scintillation properties of BaF2sbnd Ce transparent ceramic

    NASA Astrophysics Data System (ADS)

    Luo, Junming; Sahi, Sunil; Groza, Michael; Wang, Zhiqiang; Ma, Lun; Chen, Wei; Burger, Arnold; Kenarangui, Rasool; Sham, Tsun-Kong; Selim, Farida A.

    2016-08-01

    Cerium doped Barium Fluoride (BaF2sbnd Ce) transparent ceramic was fabricated and its luminescence and scintillation properties were studied. The photoluminescence shows the emission peaks at 310 nm and 323 nm and is related to the 5d-4f transitions in Ce3+ ion. Photo peak at 511 keV and 1274 keV were obtained with BaF2sbnd Ce transparent ceramic for Na-22 radioisotopes. Energy resolution of 13.5% at 662 keV is calculated for the BaF2sbnd Ce transparent ceramic. Light yield of 5100 photons/MeV was recorded for BaF2sbnd Ce(0.2%) ceramic and is comparable to its single crystal counterpart. Scintillation decay time measurements shows fast component of 58 ns and a relatively slow component of 434 ns under 662 keV gamma excitation. The slower component in BaF2sbnd Ce(0.2%) ceramic is about 200 ns faster than the STE emission in BaF2 host and is associated with the dipole-dipole energy transfer from the host matrix to Ce3+ luminescence center.

  20. EPR study of La 2- xM xCuO 4 (M = Sr, Ba)

    NASA Astrophysics Data System (ADS)

    Khan, Shakeel; Singh, Arti; Singh, R. J.

    1998-06-01

    EPR spectra of deoxygenated La 1.81Sr 0.19CuO 4 and La 1.94Ba 0.06CuO 4 have been investigated. In both of them 4 Cu 2+ ions are found to combine ferromagnetically to give S = 2 spectra. At low {Sr}/{Ba} content the spins probably start getting polarised in the ab plane. Spin-Hamiltonian parameters for all the spectra have been determined. Dependence of Tc on the content of Sr or Ba has been attempted to be explained. It seems that holes which are generated on the substitution of La 3+ by Sr 2+ or Ba 2+ and are current carriers first get uniformly distributed over the LaO plane but on increasing Sr 2+ or Ba 2+ content, they may combine together to form O 22- peroxide ions and become unable to carry current. On further increasing the Sr 2+ or Ba 2+ content, the same process is repeated, until the substance becomes metallic or until further amounts of the substituents can bot be dissolved in the parent compound.

  1. [Effects of BaP exposure on ultrastructures of hepatic cells of Boleophthalmus pectinirostris].

    PubMed

    Feng, Tao; Zheng, Weiyun; Ouyang, Gaoliang; Hong, Wanshu

    2003-10-01

    The changes of ultrastructures of hepatic cells of Boleophthalmus pectinirostris were investigated after the fish were exposed under benzo(a) pyrene in different concentrations under experimental condition. The results showed that the organelles in hepatic cells of B. pectinirostris were damaged to different extents after the fish was exposed under lower concentration of BaP (0.5 mg.L-1) for up to 7 d, in which, mitochondria and endoplasmic reticulum were the chief organelles affected by BaP exposure. While the fish was exposed under higher concentration of BaP (5 mg.L-1) for 2 h, almost all of the organelles including mitochondria and endoplasmic reticulum in hepatic cells of B. pectinirostr were affected by BaP exposure. The structures of liver cells were seriously damaged. It was demonstrated that BaP could produce multiorganalle lesions in hepatic cells of B. pectinirostris, and the severity extent of such lesions was dependent on the concentration level of BaP.

  2. Photoresponse properties of BaSi2 film grown on Si (100) by vacuum evaporation

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    We have succeeded in the observation of high photoresponsivity of orthorhombic BaSi2 film grown on crystalline Si by a vacuum evaporation method, raising the prospect of its promising application in high-efficiency thin-film solar cells. Photocurrent was observed at photon energies larger than 1.28 eV, which corresponds to the band gap of evaporated BaSi2 film, indicating that the photoresponsivity originates from the BaSi2 film. The effect of the substrate temperature on the film’s properties was also investigated. The films grown at a substrate temperature larger than 500 °C are single-phase polycrystalline BaSi2 films, while those grown at a substrate temperature of 400 °C is a mixture of phases. We confirmed that undoped evaporated BaSi2 films are an n-type material with high carrier concentration. High carrier lifetime of 4.8 and 2.7 μs can be found for the films grown at 500 °C and 400 °C, respectively. BaSi2 film grown at a substrate temperature of 500 °C, which is crack-free and single-phase, shows the best photoresponsivity. The maximum value of photocurrent was obtained at photon energy of 1.9 eV, corresponding to an external quantum efficiency of 22% under reverse applied voltage of 2 V.

  3. Systematic investigation of chemical substitution in BaSnO3 using the combinatorial approach

    NASA Astrophysics Data System (ADS)

    Takeuchi, Ichiro; Shin, Jongmoon; Lee, Seunghun; Zhang, Xiaohang; Jaim, H. M. Iftekhar; Jeong, Se-Young

    BaSnO3 has been regarded as a possible material for photo-catalysis, dielectric capacitors, and transparent conductors. We are systematically investigating the effect of chemical substitution for A and B sites in BaSnO3 using a high-throughput methodology. We have thus far investigated the effect of substituting La and Sr for the Ba-site and Pb and Bi for the Sn-site. The composition spread films were prepared on MgO, SrTiO3 and LaAlO3 using combinatorial pulsed laser deposition. The lattice parameters and band-gap energies were found to continually change as a function of the concentration of each substitutional dopant. We find that the band gap can be tuned from 2.8 eV for BaSn0.05Pb0.95O3 to 4.5 eV for Ba0.05La0.95SnO3. Especially for Ba1-xLaxSnO3 with x in the range of 0.05

  4. Insecticidal peptides from the theraposid spider Brachypelma albiceps: an NMR-based model of Ba2.

    PubMed

    Corzo, Gerardo; Bernard, Cedric; Clement, Herlinda; Villegas, Elba; Bosmans, Frank; Tytgat, Jan; Possani, Lourival D; Darbon, Herve; Alagón, Alejandro

    2009-08-01

    Soluble venom and purified fractions of the theraposid spider Brachypelma albiceps were screened for insecticidal peptides based on toxicity to crickets. Two insecticidal peptides, named Ba1 and Ba2, were obtained after the soluble venom was separated by high performance liquid chromatography and cation exchange chromatography. The two insecticidal peptides contain 39 amino acid residues and three disulfide bonds, and based on their amino acid sequence, they are highly identical to the insecticidal peptides from the theraposid spiders Aphonopelma sp. from the USA and Haplopelma huwenum from China indicating a relationship among these genera. Although Ba1 and Ba2 were not able to modify currents in insect and vertebrate cloned voltage-gated sodium ion channels, they have noteworthy insecticidal activities compared to classical arachnid insecticidal toxins indicating that they might target unknown receptors in insect species. The most abundant insecticidal peptide Ba2 was submitted to NMR spectroscopy to determine its 3-D structure; a remarkable characteristic of Ba2 is a cluster of basic residues, which might be important for receptor recognition.

  5. Preparation, characterization and magnetic properties of the BaFe12O19 @ chitosan composites

    NASA Astrophysics Data System (ADS)

    Li, Lei; Zhang, Zunju; Xie, Yu; Zhao, Jie

    2016-07-01

    The BaFe12O19 @ chitosan composites are synthesized by the crosslinking reaction through chitosan and glutaraldehyde onto the surface of BaFe12O19. The structures of the samples were characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The shape and size were observed by scanning electron microscopy and transmission electron microscopy. These results showed that chitosan has been decorated onto the surface of BaFe12O19, and the chitosan-glutaraldehyde Schiff-base composites have also been formed within the chitosan layers. Then, the magnetic properties of the samples were tested with the vibrating sample magnetometer. The magnetic saturation (MS), residual magnetization (Mr) and coercive force (Hc) values of the BaFe12O19 @ chitosan Schiff-base composite have achieved 44.94 emu/g, 27.82 emu/g and 3580.7 Oe, respectively. Compared with single BaFe12O19, the MS, and Mr of the BaFe12O19 @ chitosan composites decreases 12.31 emu/g and 8.58 emu/g, respectively. Finally, based on the experimental results, the probable formation mechanism of this composite has been investigated.

  6. Octupole deformation in 144,146Ba measured by Coulomb excitation of radioactive beams

    NASA Astrophysics Data System (ADS)

    Bucher, Brian; Zhu, Shaofei; ANL, LBNL, LLNL, Rochester, Florida State, Liverpool, Maryland, Notre Dame, Ohio, W. Scotland Collaboration

    2015-10-01

    The exotic, neutron-rich 144Ba (t1 / 2 = 11.5 s) and 146Ba (t1 / 2 = 2.2 s) nuclei are expected to exhibit some of the strongest octupole correlations in A < 200 systems. Up to now, evidence for such strong octupole correlations has been inferred from observations of low-lying negative-parity states and from the interleaving of positive- and negative-parity levels in the ground-state band. However, the E1 transition strengths are very different in these two nuclei, with two orders of magnitude reduction in 146Ba. In this experiment, we measure the octupole strength directly by Coulomb excitation of post-accelerated 144,146Ba beams produced at CARIBU using CHICO2 and GRETINA. In 144Ba, we found B(E3;3 -->0) = 48(-34+ 25) W.u., a value considerably larger than theoretical predictions, while preliminary results for 146Ba are also indicative of strong octupole collectivity. The experimental conditions, the analysis, and the results from these challenging new measurements will be presented. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 (ANL), DE-AC02-05CH11231 (LBNL, GRETINA), DOE DE-AC52-07NA27344 (LLNL), and NSF.

  7. Probing the Metal-Insulator Transition in BaTiO3 by Electrostatic Doping

    NASA Astrophysics Data System (ADS)

    Raghavan, Santosh; Zhang, Jack Y.; Shoron, Omor F.; Stemmer, Susanne

    2016-07-01

    The metal-to-insulator transition in BaTiO3 is investigated using electrostatic doping, which avoids effects from disorder and strain that would accompany chemical doping. SmTiO3/BaTiO3/SrTiO3 heterostructures are doped with a constant sheet carrier density of 3 ×1014 cm-2 that is introduced via the polar SmTiO3/BaTiO3 interface. Below a critical BaTiO3 thickness, the structures exhibit metallic behavior with high carrier mobilities at low temperatures, similar to SmTiO3/SrTiO3 interfaces. Above this thickness, data indicate that the BaTiO3 layer becomes ferroelectric. The BaTiO3 lattice parameters increase to a value consistent with a strained, tetragonal unit cell, the structures are insulating below ˜125 K , and the mobility drops by more than an order of magnitude, indicating self-trapping of carriers. The results shed light on the interplay between charge carriers and ferroelectricity.

  8. Photoluminescent BaMoO{sub 4} nanopowders prepared by complex polymerization method (CPM)

    SciTech Connect

    Azevedo Marques, Ana Paula de . E-mail: apamarques@liec.ufscar.br; Melo, Dulce M.A. de; Paskocimas, Carlos A.; Pizani, Paulo S.; Joya, Miryam R.; Leite, Edson R.; Longo, Elson

    2006-03-15

    The BaMoO{sub 4} nanopowders were prepared by the Complex Polymerization Method (CPM). The structure properties of the BaMoO{sub 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{sub 4} at 300 deg. C was disordered. At 400 deg. C and higher temperature, BaMoO{sub 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{sub 4} nanopowders, with the advantages of lower temperature, smaller time and reduced cost. The optical properties observed for BaMoO{sub 4} nanopowders suggested that this material is a highly promising candidate for photoluminescent applications.

  9. Ba6Sn6Se13: a new mixed valence selenostannate with NLO property.

    PubMed

    Feng, Kai; Jiang, Xingxing; Kang, Lei; Yin, Wenlong; Hao, Wenyu; Lin, Zheshuai; Yao, Jiyong; Wu, Yicheng; Chen, Chuangtian

    2013-10-01

    A new ternary selenostannate Ba6Sn6Se13 has been synthesized by a high temperature solid-state method. The compound crystallizes in the non-centrosymmetric orthorhombic space group P2(1)2(1)2(1) and may be represented as Ba6Sn5(2+)Sn(4+)Se13 with mixed valence Sn atoms. Sn(4+) cations lie in a tetrahedral environment, while Sn(2+) cations are found in two kinds of coordination environments: the trigonal pyramid and quadrangular pyramid. SnSe(n) (n = 3, 4, 5) polyhedra are further connected to generate a three-dimensional framework with Ba(2+) residing in cavities. Ba6Sn6Se13 shows moderate nonlinear optical response and is the first reported NLO compound in the Ba-Sn-Se system. In addition, diffuse reflectance spectroscopy measurement indicates that the band gap of Ba6Sn6Se13 is 1.52(2) eV and thermal analysis suggests that the compound melts incongruently. The theoretically calculated SHG response and band gap are in good agreement with experimental results.

  10. Insecticidal peptides from the theraposid spider Brachypelma albiceps: an NMR-based model of Ba2.

    PubMed

    Corzo, Gerardo; Bernard, Cedric; Clement, Herlinda; Villegas, Elba; Bosmans, Frank; Tytgat, Jan; Possani, Lourival D; Darbon, Herve; Alagón, Alejandro

    2009-08-01

    Soluble venom and purified fractions of the theraposid spider Brachypelma albiceps were screened for insecticidal peptides based on toxicity to crickets. Two insecticidal peptides, named Ba1 and Ba2, were obtained after the soluble venom was separated by high performance liquid chromatography and cation exchange chromatography. The two insecticidal peptides contain 39 amino acid residues and three disulfide bonds, and based on their amino acid sequence, they are highly identical to the insecticidal peptides from the theraposid spiders Aphonopelma sp. from the USA and Haplopelma huwenum from China indicating a relationship among these genera. Although Ba1 and Ba2 were not able to modify currents in insect and vertebrate cloned voltage-gated sodium ion channels, they have noteworthy insecticidal activities compared to classical arachnid insecticidal toxins indicating that they might target unknown receptors in insect species. The most abundant insecticidal peptide Ba2 was submitted to NMR spectroscopy to determine its 3-D structure; a remarkable characteristic of Ba2 is a cluster of basic residues, which might be important for receptor recognition. PMID:19374957

  11. Magnetic ordering of the buckled honeycomb lattice antiferromagnet Ba2NiTeO6

    NASA Astrophysics Data System (ADS)

    Asai, Shinichiro; Soda, Minoru; Kasatani, Kazuhiro; Ono, Toshio; Avdeev, Maxim; Masuda, Takatsugu

    2016-01-01

    We investigate the magnetic order of the buckled honeycomb lattice antiferromagnet Ba2NiTeO6 and its related antiferromagnet Ba3NiTa2O9 by neutron diffraction measurements. We observe magnetic Bragg peaks below the transition temperatures, and identify propagation vectors for these oxides. A combination of representation analysis and Rietveld refinement leads to a collinear magnetic order for Ba2NiTeO6 and a 120∘ structure for Ba3NiTa2O9 . We find that the spin model of the bilayer triangular lattice is equivalent to that of the two-dimensional buckled honeycomb lattice having magnetic frustration. We discuss the magnetic interactions and single-ion anisotropy of Ni+2 ions for Ba2NiTeO6 in order to clarify the origin of the collinear magnetic structures. Our calculation suggests that the collinear magnetic order of Ba2NiTeO6 is induced by the magnetic frustration and easy-axis anisotropy.

  12. Chemical processing and dielectric properties of BaTiO{sub 3} ceramics

    SciTech Connect

    Hayashi, Takashi; Satoh, Kimihiko; Suganuma, Katsuaki

    1995-09-01

    BaTiO{sub 3} powders were prepared at room temperature by the hydrolysis of a Ba-Ti solution, which was obtained by mixing titanium isopropoxide and a methanol suspension of barium hydroxide. As-prepared powders were crystalline with the average particle size of less than 30nm. The crystallinity and dielectric properties of as-prepared BaTiO{sub 3} powders depended upon the amount of water. Highly crystalline BaTiO{sub 3} powders were obtained, when the hydrolysis of Ba-Ti solution was performed with excess amount of water (molar ratio of H{sub 2}O/alkoxide {ge} 60). BaTiO{sub 3} ceramics from the powders obtained with H{sub 2}O/alkoxide=60 exhibited a dielectric constant of about 4500 and loss tangent of about 0.02. The micro- structure exhibited the bimodal grain structure consisting of exaggerated grains (>50 {mu} m) and small grains (about 1 {mu} m).

  13. A novel LiCl-BaCl2:Eu2+ eutectic scintillator for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Wu, Yuntao; Lukosi, Eric D.; Zhuravleva, Mariya; Lindsey, Adam C.; Melcher, Charles L.

    2015-10-01

    A natLiCl-BaCl2:Eu2+ eutectic scintillator was synthesized by the vertical Bridgman method aiming at the application of thermal neutron detection. The molar ratio of LiCl and BaCl2 was 75.1/24.9, which corresponds to the eutectic composition in the LiCl-BaCl2 system. The grown eutectic showed a periodic microstructure of BaCl2:Eu2+ and LiCl phases with 2-3 μm thickness. The α-particle induced radioluminescence spectrum of the scintillator showed an intense emission peak at 406 nm due to the Eu2+ 5d1→4f emission from the BaCl2:Eu2+ phase and an additional weak emission peak at 526 nm. The scintillation decay time was 412 ns. LiCl-BaCl2:Eu2+ eutectic samples exhibited non-correlated neutron detection efficiency and light yield as a function of crystal length, suggesting material non-uniformities within the boule. The relative light yield was equal to or greater than that of Nucsafe lithium glass. Gamma-ray exposures indicate that gamma/neutron threshold discrimination for higher energy gamma-rays will be limited.

  14. Synthesis of Y1Ba2Cu3O(sub x) superconducting powders by intermediate phase reaction

    NASA Technical Reports Server (NTRS)

    Moore, C.; Fernandez, J. F.; Recio, P.; Duran, P.

    1990-01-01

    One of the more striking problems for the synthesis of the Y1Ba2Cu3Ox compound is the high-temperature decomposition of the BaCO3. This compound is present as raw material or as an intermediate compound in chemical processes such as amorphous citrate, coprecipitation oxalate, sol-gel process, acetate pyrolisis, etc. This fact makes difficult the total formation reaction of the Y1Ba2Cu3Ox phase and leads to the presence of undesirable phases such as the BaCuO2 phase, the 'green phase', Y2BaCuO5 and others. Here, a new procedure to overcome this difficulty is studied. The barium cation is previously combined with yttrium and/or copper to form intermediate compounds which can react between them to give Y1Ba2Cu3Ox. BaY2O4 and BaCu2O3 react according to the equation BaY2O4+3BaCu2O3 yields 2Y1Ba2Cu3Ox. BaY2O4 is a stable compound of the Y2O3-BaO system; BaCu2O3 is an intimate mixture of BaCuO2 and uncombined CuO. The reaction kinetics of these phases have been established between 860 and 920 C. The phase evolution has been determined. The crystal structure of the Y1Ba2Cu3Ox obtained powder was studied. According to the results obtained from the kinetics study the Y1Ba2Cu3Ox the synthesis was performed at temperatures of 910 to 920 C for short treatment times (1 to 2 hours). Pure Y1Ba2Cu3Ox was prepared, which develops orthorombic type I structure despite of the cooling cycle. Superconducting transition took place at 91 K. The sintering behavior and the superconducting properties of sintered samples were studied. Density, microstructure and electrical conductivity were measured. Sintering densities higher than 95 percent D(sub th) were attained at temperatures below 940 C. Relatively fine grained microstructure was observed, and little or no-liquid phase was detected.

  15. An investigation of new infrared nonlinear optical material: BaCdSnSe4, and three new related centrosymmetric compounds: Ba2SnSe4, Mg2GeSe4, and Ba2Ge2S6.

    PubMed

    Wu, Kui; Su, Xin; Yang, Zhihua; Pan, Shilie

    2015-12-14

    A series of new metal chalcongenides, BaCdSnSe4 (1), Ba2SnSe4 (2), Mg2GeSe4 (3), and Ba2Ge2S6 (4), were successfully synthesized for the first time. Among them, compounds 2 and 4 were prepared by a molten flux method with Zn as the flux. In their structures, all of them have MQ4 (M = Sn, Ge; Q = S, Se) units. For compound 1, the CdSe4 and SnSe4 groups are connected to form CdSnSe6 layers and these layers are linked together by the Ba atoms. Compounds 2 and 3 are composed of isolated MSe4 (M = Sn, Ge) units and charge-balanced by the Ba or Mg atoms, respectively, while compound 4 has infinite ∞(GeS3)n chains, which is different from the structures of the other three compounds that only have isolated MSe4 (M = Sn, Ge) units. The measured IR and Raman data of the title compounds show wide infrared transmission ranges. The experimental band gaps of compounds 1, 2, 3 and were determined to be 1.79, 1.90, and 2.02 eV, respectively. Band structures were also calculated and indicate that their tetrahedral units, such as [SnSe4], [GeS4] and [GeSe4], determine the energy band gaps of the title compounds, respectively. As for compound 1, based on fundamental light at 2.09 μm, the experimental second harmonic generation (SHG) response is about 1.6 times that of the benchmark AgGaS2, which is also consistent with the calculated value. Based on the above results, compound 1 has promising applications in the IR field as a NLO material. PMID:26509847

  16. Environmental Stress-Dependent Effects of Deletions Encompassing Hsp70Ba on Canalization and Quantitative Trait Asymmetry in Drosophila melanogaster

    PubMed Central

    Takahashi, Kazuo H.; Daborn, Phillip J.; Hoffmann, Ary A.; Takano-Shimizu, Toshiyuki

    2011-01-01

    Hsp70 genes may influence the expression of wing abnormalities in Drosophila melanogaster but their effects on variability in quantitative characters and developmental instability are unclear. In this study, we focused on one of the six Hsp70 genes, Hsp70Ba, and investigated its effects on within-and among-individual variability in orbital bristle number, sternopleural bristle number, wing size and wing shape under different environmental conditions. To do this, we studied a newly constructed deletion, Df(3R)ED5579, which encompasses Hsp70Ba and nine non-Hsp genes, in the heterozygous condition and another, Hsp70Ba304, which deletes only Hsp70Ba, in the homozygous condition. We found no significant effect of both deletions on within-individual variation quantified by fluctuating asymmetry (FA) of morphological traits. On the other hand, the Hsp70Ba304/Hsp70Ba304 genotype significantly increased among-individual variation quantified by coefficient of variation (CV) of bristle number and wing size in female, while the Df(3R)ED5579 heterozygote showed no significant effect. The expression level of Hsp70Ba in the deletion heterozygote was 6 to 20 times higher than in control homozygotes, suggesting that the overexpression of Hsp70Ba did not influence developmental stability or canalization significantly. These findings suggest that the absence of expression of Hsp70Ba increases CV of some morphological traits and that HSP70Ba may buffer against environmental perturbations on some quantitative traits. PMID:21541022

  17. New insights into BaP-induced toxicity: role of major metabolites in transcriptomics and contribution to hepatocarcinogenesis.

    PubMed

    Souza, Terezinha; Jennen, Danyel; van Delft, Joost; van Herwijnen, Marcel; Kyrtoupolos, Soterios; Kleinjans, Jos

    2016-06-01

    Benzo(a)pyrene (BaP) is a ubiquitous carcinogen resulting from incomplete combustion of organic compounds and also present at high levels in cigarette smoke. A wide range of biological effects has been attributed to BaP and its genotoxic metabolite BPDE, but the contribution to BaP toxicity of intermediary metabolites generated along the detoxification path remains unknown. Here, we report for the first time how 3-OH-BaP, 9,10-diol and BPDE, three major BaP metabolites, temporally relate to BaP-induced transcriptomic alterations in HepG2 cells. Since BaP is also known to induce AhR activation, we additionally evaluated TCDD to source the expression of non-genotoxic AhR-mediated patterns. 9,10-Diol was shown to activate several transcription factor networks related to BaP metabolism (AhR), oxidative stress (Nrf2) and cell proliferation (HIF-1α, AP-1) in particular at early time points, while BPDE influenced expression of genes involved in cell energetics, DNA repair and apoptotic pathways. Also, in order to grasp the role of BaP and its metabolites in chemical hepatocarcinogenesis, we compared expression patterns from BaP(-metabolites) and TCDD to a signature set of approximately nine thousand gene expressions derived from hepatocellular carcinoma (HCC) patients. While transcriptome modulation by TCDD appeared not significantly related to HCC, BaP and BPDE were shown to deregulate metastatic markers via non-genotoxic and genotoxic mechanisms and activate inflammatory pathways (NF-κβ signaling, cytokine-cytokine receptor interaction). BaP also showed strong repression of genes involved in cholesterol and fatty acid biosynthesis. Altogether, this study provides new insights into BaP-induced toxicity and sheds new light onto its mechanism of action as a hepatocarcinogen.

  18. Cage-forming compounds in the Ba-Rh-Ge system: from thermoelectrics to superconductivity.

    PubMed

    Falmbigl, M; Kneidinger, F; Chen, M; Grytsiv, A; Michor, H; Royanian, E; Bauer, E; Effenberger, H; Podloucky, R; Rogl, P

    2013-01-18

    Phase relations and solidification behavior in the Ge-rich part of the phase diagram have been determined in two isothermal sections at 700 and 750 °C and in a liquidus projection. A reaction scheme has been derived in the form of a Schulz-Scheil diagram. Phase equilibria are characterized by three ternary compounds: τ(1)-BaRhGe(3) (BaNiSn(3)-type) and two novel phases, τ(2)-Ba(3)Rh(4)Ge(16) and τ(3)-Ba(5)Rh(15)Ge(36-x), both forming in peritectic reactions. The crystal structures of τ(2) and τ(3) have been elucidated from single-crystal X-ray intensity data and were found to crystallize in unique structure types: Ba(3)Rh(4)Ge(16) is tetragonal (I4/mmm, a = 0.65643(2) nm, c = 2.20367(8) nm, and R(F) = 0.0273), whereas atoms in Ba(5)Rh(15)Ge(36-x) (x = 0.25) arrange in a large orthorhombic unit cell (Fddd, a = 0.84570(2) nm, b = 1.4725(2) nm, c = 6.644(3) nm, and R(F) = 0.034). The body-centered-cubic superstructure of binary Ba(8)Ge(43)□(3) was observed to extend at 800 °C to Ba(8)Rh(0.6)Ge(43)□(2.4), while the clathrate type I phase, κ(I)-Ba(8)Rh(x)Ge(46-x-y)□(y), reveals a maximum solubility of x = 1.2 Rh atoms in the structure at a vacancy level of y = 2.0. The cubic lattice parameter increases with increasing Rh content. Clathrate I decomposes eutectoidally at 740 °C: κ(I) ⇔ (Ge) + κ(IX) + τ(2). A very small solubility range is observed at 750 °C for the clathrate IX, κ(IX)-Ba(6)Rh(x)Ge(25-x) (x ∼ 0.16). Density functional theory calculations have been performed to derive the enthalpies of formation and densities of states for various compositions Ba(8)Rh(x)Ge(46-x) (x = 0-6). The physical properties have been investigated for the phases κ(I), τ(1), τ(2), and τ(3), documenting a change from thermoelectric (κ(I)) to superconducting behavior (τ(2)). The electrical resistivity of κ(I)-Ba(8)Rh(1.2)Ge(42.8)□(2.0) increases almost linearly with the temperature from room temperature to 730 K, and the Seebeck coefficient is negative

  19. Preparation of LTCC materials with adjustable permittivity based on BaO–B{sub 2}O{sub 3}–SiO{sub 2}/BaTiO{sub 3} system

    SciTech Connect

    Wang, Kai-tuo; He, Yan; Liang, Zhong-yuan; Cui, Xue-min

    2015-05-15

    Graphical abstract: The dielectric constant (ϵ) of the sintered BaO–B{sub 2}O{sub 3}–SiO{sub 2}/BaTiO{sub 3} glass/ceramics (the sintered samples with line shrinkage of 10%) changed from 5 to 30 and the dielectric losses (tanδ) was lower than 0.05 at 100 MHz with the amount of BaTiO{sub 3} additive increment from 60 wt% to 90 wt% fraction. - Highlights: • The ϵ of BaO–B{sub 2}O{sub 3}–SiO{sub 2} glass can be adjusted from 5 to 30 by adding BaTiO{sub 3}. • The influence factors on dielectric are the secondary phase and microstructure. • BaO–B{sub 2}O{sub 3}–SiO{sub 2}/BaTiO{sub 3} system can fabricate LTCC when BaTiO{sub 3} located in 60–80 wt%. - Abstract: This paper studied the preparation and characterization of LTCC (low temperature co-fired ceramics) materials based on BaO–B{sub 2}O{sub 3}–SiO{sub 2}/BaTiO{sub 3} glass–ceramics, where the sintering temperature was about 900 °C and dielectric constant was effectively adjustable from 5 to 30 by changing the BaTiO{sub 3} fraction from 60 wt% to 90 wt%. X-ray diffractometer (XRD), scanning electron microscopy (SEM) were used to examine the effect of different amounts additive on the dielectric properties of this LTCC system and the crystal structure change. The results indicated that BaTiO{sub 3} can be used as a dielectric additive aim to adjust the permittivity of BaO–B{sub 2}O{sub 3}–SiO{sub 2} glass, which the main influence factors on dielectric are the contents of the secondary phase, the BaTiO{sub 3} phase fraction and the porous structure of the sintered body. Therefore, the microstructure and dielectric property of BaO–B{sub 2}O{sub 3}–SiO{sub 2}/BaTiO{sub 3} glass–ceramics composites could be controlled by adjusting the content of BaTiO{sub 3} additive.

  20. Search for compounds of the NaBaR(BO{sub 3}){sub 2} family (R = La, Nd, Gd, and Yb) and the new NaBaYb(BO{sub 3}){sub 2} orthoborate

    SciTech Connect

    Svetlyakova, T. N. Kokh, A. E.; Kononova, N. G.; Fedorov, P. P.; Rashchenko, S. V.; Maillard, A.

    2013-01-15

    A search for compounds of the NaBaR(BO{sub 3}){sub 2} composition (where R = La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, or Yb{sup 3+}) is performed by solid state synthesis and spontaneous crystallization. A new compound, NaBaYb(BO{sub 3}){sub 2}, is found in this series. It crystallizes in space group R3{sup -} and belongs to the family of sublayer complex orthoborates with isolated BO{sub 3} groups NaBaR(BO{sub 3}){sub 2} (R = Y, Sc, and Yb). Theoretical X-ray powder diffraction patterns of NaBaY(BO{sub 3}){sub 2}, NaBaSc(BO{sub 3}){sub 2}, and NaBaYb(BO{sub 3}){sub 2} are calculated based on single-crystal data.

  1. Comparison of the dynamics of the reactions of Ba with aromatic halides and alkyl halides LIF studies of the reactions of Ba with C 6H 5X (X  Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Han, Ke-Li; He, Guo-Zhong; Lou, Nan-Quan

    1993-03-01

    Nascent internal state energy distributions of BaX have been studied for the reactions Ba + C 6H 5X→BaX+C 6H 5 (X  Cl, Br, 1) using the laser-induced fluorescence method in a beam-gas arrangement. The energy disposal differs markedly from that of the reactions Ba + CH 3X. With the change of X from Cl to I, the vibrational excitations and the reactive cross sections decrease for the reactions Ba + C 6H 5X, whereas those of the reactions Ba + CH 3X increase. The CNDO/2 calculations of C 6H 5X and CH 3X have been used to interpret the experimental results qualitatively.

  2. Effect of the [Ba2BO3F]∞ Layer on the Band Gap: Synthesis, Characterization, and Theoretical Studies of BaZn2B2O6·nBa2BO3F (n = 0, 1, 2).

    PubMed

    Wu, Hongping; Su, Xin; Han, Shujuan; Yang, Zhihua; Pan, Shilie

    2016-05-16

    Two new zincoborate fluorides with the common formula BaZn2B2O6·nBa2BO3F (n = 1, 2) have been successfully synthesized for the relationship study between the band gaps and crystal structures in zinc-containing borate fluorides. Ba3Zn2B3O9F with n = 1 in the common formula belongs to the orthorhombic space group Pnma (No. 20), and Ba5Zn2B4O12F2 with n = 2 in the common formula crystallizes in the monoclinic space group C2/c (No. 62). They can both be seen as compounds with the n[Ba2BO3F]∞ (n = 1 or 2) layer inserted in the structure of BaZn2B2O6. UV-vis-near-IR diffuse-reflectance spectra show that the band gaps of BaZn2B2O6·nBa2BO3F (n = 0, 1, 2) gradually increase with more [Ba2BO3F]∞ layers inserted. The first-principles calculation indicates that the inserted n[Ba2BO3F]∞ layers play a positive effect in increasing the band gaps of zincoborate fluorides. Furthermore, the IR spectra, thermal behaviors, and refractive indices of these compounds are also studied. PMID:27119618

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Effect of divalent Ba cation substitution with Sr on coupled 'multiglass' state in the magnetoelectric multiferroic compound Ba3NbFe3Si2O14.

    PubMed

    Rathore, Satyapal Singh; Vitta, Satish

    2015-01-01

    (Ba/Sr)3NbFe3Si2O14 is a magneto-electric multiferroic with an incommensurate antiferromagnetic spiral magnetic structure which induces electric polarization at 26 K. Structural studies show that both the compounds have similar crystal structure down to 6 K. They exhibit a transition, TN at 26 K and 25 K respectively, as indicated by heat capacity and magnetization, into an antiferromagnetic state. Although Ba and Sr are isovalent, they exhibit very different static and dynamic magnetic behaviors. The Ba-compound exhibits a glassy behavior with critical slowing dynamics with a freezing temperature of ~35 K and a critical exponent of 3.9, a value close to the 3-D Ising model above TN, in addition to the invariant transition into an antiferromagnetic state. The Sr-compound however does not exhibit any dispersive behavior except for the invariant transition at TN. The dielectric constant reflects magnetic behavior of the two compounds: the Ba-compound has two distinct dispersive peaks while the Sr-compound has a single dispersive peak. Thus the compounds exhibit coupled 'multiglass' behavior. The difference in magnetic properties between the two compounds is found to be due to modifications to super exchange path angle and length as well as anti-site defects which stabilize either ferromagnetic or antiferromagnetic interactions. PMID:25988657

  5. Linking large piezoelectric coefficients to highly flexible polarization of lead free BaTiO3-CaTiO3-BaZrO3 ceramics

    NASA Astrophysics Data System (ADS)

    Benabdallah, F.; Simon, A.; Khemakhem, H.; Elissalde, C.; Maglione, M.

    2011-06-01

    We report a large d31 piezoelectric coefficient and corresponding electromechanical coupling factor, Kp, of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BCTZ50) and 0.68Ba(Zr0.2Ti0.8)O3-0.32(Ba0.7Ca0.3)TiO3 (BCTZ32) lead-free piezoceramics. The piezoelectric coefficient, d31, reaches a high value of 200 pC/N for BCTZ50 at room temperature which is comparable to the one of the soft PZT. This confirms the previously reported d33 for the same material. A useful way to achieve such performances at the expense of a smaller thermal budget is suggested, enabling better control of the ceramics composition and microstructure. Based on pyroelectric and ferroelectric hysteresis loops measurements, we show that such outstanding properties are likely due to the high flexibility of polarization under thermal and electric stresses.

  6. TuBaFrost: European virtual tumor tissue banking.

    PubMed

    Riegman, P H J; Oomen, M H A; Dinjens, W N M; Oosterhuis, J W; Lam, K H; Spatz, A; Ratcliffe, C; Knox, K; Mager, R; Kerr, D; Pezzella, F; Van Damme, B; Van De Vijver, M; Van Boven, H; Morente, M M; Alonso, S; Kerjaschki, D; Pammer, J; López-Guerrero, J A; Llombart-Bosch, A; Carbone, A; Gloghini, A; Teodorovic, I; Isabelle, M; Passioukov, A; Lejeune, S; Therasse, P; Van Veen, E B

    2006-01-01

    TuBaFrost is a consortium responsible for the task to create a virtual European human frozen tumor tissue bank, composed of high quality frozen tumor tissue collections with corresponding accurate diagnosis stored in European cancer centers and universities, searchable on the Internet, providing rules for access and use and a code of conduct to comply with the various legal and ethical regulations in European countries. Such infrastructure would enlarge tissue availability and accessibility in large amounts of specified or even rare tumor samples. Design of an infrastructure for European residual tissue banking with the described characteristics, clear focus points emerge that can be broken down in dedicated subjects: (1) standardization and quality assurance (QA) to avoid inter-institute quality variation; (2) law and ethics enabling exchange of tissue samples possible between institutes in the different European countries, where law and ethics are characterized by a strong variability; (3) rules for access, with sufficient incentives for collectors; (4) central database application containing innovations on search and selection procedures; (5) support when needed with histology images; and (6) Internet access to search and upload, with in addition a solid website giving proper information on the procedures, intentions and activities not only to the scientific community, but also to the general public. One consortium decision, part of the incentives for collectors, had major impact on the infrastructure; custodianship over the tissues as well as the tissues stay with the collector institute. Resulting in specimens that are not given to an organization, taking decisions on participation of requests, but instead the local collected tissues stay very easy to access by the collector and allows autonomous negotiation between collector and requestor on cooperation, coauthorship in publication or compensation in costs. Thereby, improving availability of large amounts of

  7. Structure and Relaxor Behaviour of Ba2+ Substituted NBT Ceramics

    NASA Astrophysics Data System (ADS)

    Rao, K. Sambasiva; Tilak, B.; Rajulu, K. Ch. Varada; Swathi, A.; Workineh, Haileeyesus; Ganagadharudu, D.

    2011-11-01

    In the course of search for environmental-friendly lead-free relaxor ferroelectrics, (Bi,Na)TiO3-(NBT) based ceramics show very good physical properties among several lead-free compositions. The NBT composition exhibits a strong ferroelectricity and high Curie temperature, and considered to be a good candidate for lead-free ceramics as a substitute for lead-based materials (e.g., PZT). In the present communication barium substituted NBT, (Na0.5Bi0.5)0.912Ba0.088TiO3-0.088BNBT composition has been prepared by conventional solid-state reaction process. The tolerance factor has been estimated and found to be 0.819, indicating the stability of the perovskite structure. The XRD analysis of the material revealed a pure perovskite with tetragonal structure. The average grain size as observed from SEM, was found to be 1.04μm. Detailed studies exhibit a relaxor behaviour with diffuse phase transition. The diffuseness parameter has been established to be 1.97. The dielectric relaxation obeyed the Vogel-Fulcher (V-F) relation. From the V-F plot, the obtained values are Tf = 305°C, Ea = 0.0131eV and νo = 2.95×105Hz, which provide the evidence of relaxor behaviour. The electrical behaviour has been probed through complex impedance spectroscopy. The frequency-dependent conductivity spectra obey the power law in the frequency range of 45Hz-5MHz and temperature range of 35 °C-60 °C.

  8. Properties of polycarbonate containing BaTiO3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Lomax, J. F.; Fontanella, J. J.; Edmondson, C. A.; Wintersgill, M. C.; Wolak, M. A.; Westgate, M. A.; Lomax, E. A.; Lomax, P. Q.; Bogle, X.; Rúa, A.; Greenbaum, S. G.

    2014-03-01

    The real part of the relative permittivity, ɛ', and dielectric loss, tan δ, have been determined at audio frequencies at temperatures from about 5 K to 350 K for nano-composites composed of BaTiO3 nanoparticles and polycarbonate. The room temperature breakdown strength was also measured and thermal analysis, nuclear magnetic resonance and scanning electron microscopy studies were carried out. For some films the nanoparticles were surface-treated (STNP) while for others they were not (UNP). For concentrations of UNP greater than about 3.4 vol. %, ɛ' is much larger than expected on the basis of laws of mixing. On the other hand, ɛ' for materials made using STNP is well-behaved. Correspondingly, increased loss (ɛ″ or tan δ) in the vicinity of room temperature is observed for the materials made from UNP. The anomalously large values of relative permittivity and increased loss are attributed to the presence of large aggregates in the materials made using the UNP. For both UNP-and STNP-based materials, the breakdown strength is found to decrease as nanoparticle concentration increases. The breakdown strength for the materials made using STNP is found to be larger for all concentrations than for those containing UNP despite the presence of large aggregates in some of the STNP-based materials. This shows that breakdown is strongly affected by the nanoparticle surfaces and/or the interface layer. It is also found that the breakdown strength for materials made using UNP increases as particle size increases. Finally, variable temperature and pressure proton nuclear magnetic resonance relaxation measurements were made to assess the effect of nanoparticle inclusion on polymer motion, and the effects were found to be very minor.

  9. Insulator-to-semiconductor transition of nanocrystalline BaTiO3 at temperatures ≤200 °C.

    PubMed

    Guo, Xin

    2014-10-14

    As a classic dielectric material, BaTiO3 is one of the most important materials used in electronic applications. In this work, highly dense BaTiO3 ceramics with an average grain size of 35 nm were prepared, and dielectric and electrical properties were investigated. Microcrystalline BaTiO3 is an insulator at low temperatures; however, nanocrystalline BaTiO3 shows considerable semiconductivity with an activation energy of only 0.27 eV at temperatures ≤200 °C. At room temperature, the conductivity of nanocrystalline BaTiO3 is about fourteen orders of magnitude higher than that of the microcrystalline counterpart. Only by decreasing the grain size, one can transform BaTiO3 from an insulator to a semiconductor.

  10. Nuclear structure of even 120-136Ba under the framework of IBM, IVBM and new method (SEF)

    NASA Astrophysics Data System (ADS)

    Al-Jubbori, Mushtaq A.; Kassim, Huda H.; Sharrad, Fadhil I.; Hossain, I.

    2016-11-01

    The positive and negative-state bands of even-even 120-136Ba nuclei have been studied. The energy levels for the ground-state band of 120-136Ba have been calculated using Interacting Boson Model (IBM), Interacting Vector Boson Model (IVBM) and a new method called Semi-Empirical Formula (SEF). The negative parity band of even-even 120-136Ba isotopes has been also calculated using (IVBM) and (SEF). The γ and β-bands of even-even 120-136Ba isotopes have been calculated using IBM and SEF. The parameters of the best fit to the measured data are determined. The reduced transition probabilities B (E 2) of these nuclei was calculated. The critical points have been determined for 134,136Ba isotopes. The potential energy surfaces for even-even Ba isotopes are studied using the simplified form of Interacting Boson Model (IBM) with an intrinsic coherent state.

  11. Crystal structure of the oxides BaCuGd/sub 2/O/sub 5/ and Ba/sub 2/Cu/sub 3/GdO/sub 7-//sub x/

    SciTech Connect

    Campa, J.A.; de Salazar, J.M.G.; Gutierrez-Puebla, E.; Monge, M.A.; Rasines, I.; Ruiz-Valero, C.

    1988-01-01

    We have grown crystals of BaCuGd/sub 2/O/sub 5/ and Ba/sub 2/Cu/sub 3/GdO/sub 7-//sub x/ and determined their structures by single-crystal x-ray diffraction. Green and black BaCuGd/sub 2/O/sub 5/ are roughly identical. In the refinement of Ba/sub 2/Cu/sub 3/GdO/sub 7-//sub x/ a value of x = 0.5 is obtained. The existence of oxygen vacancies is compatible with an incommensurable system and also with high-order superstructures.

  12. Surfactant-assisted synthesis of mono-dispersed cubic BaTiO{sub 3} nanoparticles

    SciTech Connect

    Hai, Chunxi; Inukai, Koji; Takahashi, Yosuke; Izu, Noriya; Akamatsu, Takafumi; Itoh, Toshio; Shin, Woosuck

    2014-09-15

    Mono-dispersed BaTiO{sub 3} nanoparticles have been prepared via the assistance of capping agent poly(vinylpyrrolidone) (PVP). - Highlights: • BaTiO{sub 3} nanoparticles with single cubic crystal structure. • Poor dispersibility of nanoparticles has been overcome by in situ modification way. • Growth competition between BaTiO3 core and polymer shell. - Abstract: In this study, poly(vinylpyrrolidone)-assisted synthesis of mono-dispersed BaTiO{sub 3} nanoparticles have been reported. The various processing parameters, namely, refluxing temperature, KOH concentration, and poly(vinylpyrrolidone) concentration, have been varied, and the effects on the growth of BaTiO{sub 3} particles have been analyzed systematically. X-ray diffraction studies indicated that poly(vinylpyrrolidone) did not affect the crystal structure, but rather influenced the crystal lattice structure. In addition, the use of surfactant poly(vinylpyrrolidone) hindered the agglomeration of the nanoparticles, and facilitated the formation of mono-dispersed core–shell organic/inorganic hybrid nanocomposite. Furthermore, the mineralizer KOH promoted the dissolution of reactants and promoted the crystallization of BaTiO{sub 3} particles. Accordingly, the dissolution-precipitation scheme was believed to be the mechanism underlying the formation of BaTiO{sub 3} particles. This was further substantiated by the experimental observations, which indicated that the nucleation and crystallization of the particles was affected by the KOH concentration in the reaction system. Finally, the formation of mono-dispersed core–shell nanocomposites proceeded via reaction limited cluster aggregation. We believe that the method proposed in this study could be extended for the synthesis of mono-dispersed nanoparticles for industrial applications.

  13. Barium isotope fractionation during witherite (BaCO3) dissolution, precipitation and at equilibrium

    NASA Astrophysics Data System (ADS)

    Mavromatis, Vasileios; van Zuilen, Kirsten; Purgstaller, Bettina; Baldermann, Andre; Nägler, Thomas F.; Dietzel, Martin

    2016-10-01

    This study examines the behavior of Ba isotope fractionation between witherite and fluid during mineral dissolution, precipitation and at chemical equilibrium. Experiments were performed in batch reactors at 25 °C in 10-2 M NaCl solution where the pH was adjusted by continuous bubbling of a water saturated gas phase of CO2 or atmospheric air. During witherite dissolution no Ba isotope fractionation was observed between solid and fluid. In contrast, during witherite precipitation, caused by a pH increase, a preferential uptake of the lighter 134Ba isotopomer in the solid phase was observed. In this case, the isotope fractionation factor αwitherite-fluid is calculated to be 0.99993 ± 0.00004 (or Δ137/134Bawitherite-fluid ≈ -0.07 ± 0.04‰, 2 sd). The most interesting feature of this study, however, is that after the attainment of chemical equilibrium, the Ba isotope composition of the aqueous phase is progressively becoming lighter, indicating a continuous exchange of Ba2+ ions between witherite and fluid. Mass balance calculations indicate that the detachment of Ba from the solid is not only restricted to the outer surface layer of the solid, but affects several (∼7 unit cells) subsurface layers of the crystal. This observation comes in excellent agreement with the concept of a dynamic system at chemical equilibrium in a mineral-fluid system, denoting that the time required for the achievement of isotopic equilibrium in the witherite-fluid system is longer compared to that observed for chemical equilibrium. Overall, these results indicate that the isotopic composition of Ba bearing carbonates in natural environments may be altered due to changes in fluid composition without a net dissolution/precipitation to be observed.

  14. Structure and magnetic properties of the cubic oxide fluoride BaFeO{sub 2}F

    SciTech Connect

    Berry, Frank J.; Coomer, Fiona C.; Hancock, Cathryn; Helgason, Orn; Moore, Elaine A.; Slater, Peter R.; Wright, Adrian J.; Thomas, Michael F.

    2011-06-15

    Fluorination of the parent oxide, BaFeO{sub 3-{delta}}, with polyvinylidine fluoride gives rise to a cubic compound with a=4.0603(4) A at 298 K. {sup 57}Fe Moessbauer spectra confirmed that all the iron is present as Fe{sup 3+}. Neutron diffraction data showed complete occupancy of the anion sites, indicating a composition BaFeO{sub 2}F, with a large displacement of the iron off-site. The magnetic ordering temperature was determined as T{sub N}=645{+-}5 K. Neutron diffraction data at 4.2 K established G-type antiferromagnetism with a magnetic moment per Fe{sup 3+} ion of 3.95 {mu}{sub B}. However, magnetisation measurements indicated the presence of a weak ferromagnetic moment that is assigned to the canting of the antiferromagnetic structure. {sup 57}Fe Moessbauer spectra in the temperature range 10-300 K were fitted with a model of fluoride ion distribution that retains charge neutrality of the perovskite unit cell. - Graphical abstract: The cubic oxide fluoride of composition BaFeO{sub 2}F has been synthesised and characterised. Highlights: > Fluorination of BaFeO{sub 3-{delta}} with polyvinylidene fluoride gives a cubic oxide fluoride of composition BaFeO{sub 2}F. > BaFeO{sub 2}F adopts a canted antiferromagnetic structure and is different from the related phase of composition SrFeO{sub 2}F. > A model of fluoride ion distribution about iron in BaFeO{sub 2}F has been explored.

  15. Ba, B, and U element partitioning in magnesian calcite skeletons of Octocorallia corals

    NASA Astrophysics Data System (ADS)

    Yoshimura, T.; Suzuki, A.; Iwasaki, N.

    2015-01-01

    Barium, boron and uranium element partitioning and oxygen and carbon isotope fractionation of high-Mg calcite skeletons of Octocorallia corals were investigated. The dissolved Ba concentration in seawater and the coral Ba/Ca ratio showed a clear positive correlation. The empirically derived barium partition coefficient is comparable to previous data for not only calcitic corals but also intermediate- to deep-water-dwelling scleractinian corals whose skeletons are composed of aragonite. Octocorallia corals are geologically important producers of biominerals, and they provide long-term records (up to hundreds of years) of environmental conditions in the deep ocean. Our data suggest that Ba/Ca ratios in Octocorallia corals may be a useful proxy for nutrients in intermediate and deep waters. The Ba/Ca ratio, a possible proxy for pH or carbonate ion concentration in seawater, showed the largest correlation with δ13C among the examined parameters. This result implies that the pH of the extracytoplasmic calcifying fluid (ECF) simultaneously influences δ18O, δ13C, and Ba/Ca by influencing the relative contributions of dissolved carbon sources in the ECF. Positive correlations of Ba/Ca with δ18 and δ13C suggest that δ18 and δ13C are enriched in light isotopes when conditions are less alkaline, suggesting a potential role of biological alkalinity pumping becomes more favorable with decreasing calcifying fluid pH. Substantial inter- and intra-specimen variations in Ba/Ca suggest that physicochemical factors do not exert a dominant systematic control on U incorporation.

  16. Investigation of structure and oxygen permeability of Ba-Ce-Co-Fe-O system

    SciTech Connect

    Li, Qiming; Zhu, Xuefeng; Yang, Weishen

    2010-09-15

    Mixed ionic-electronic conducting perovskite oxides, BaCe{sub 0.1}Co{sub x}Fe{sub 0.9-x}O{sub 3-{delta}}, were synthesized with a combined citric acid and EDTA complexing method. The structure and oxygen permeability of BaCe{sub 0.1}Co{sub x}Fe{sub 0.9-x}O{sub 3-{delta}} series was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and oxygen permeation operation. XRD characterization showed that pure cubic perovskite structure can be obtained only if the content of cobalt and cerium in B-site of Ba-Ce-Co-Fe-O series is no more than 40% and 15%, respectively. Lattice parameters of BaCe{sub 0.1}Co{sub x}Fe{sub 0.9-x}O{sub 3-{delta}} gradually increase with cobalt and cerium content, iodine titration experiment revealed that the doping of cerium ions with big radius can keep B-site cobalt and iron ions in low valence state. Oxygen permeation operation showed that oxygen permeation flux of all BaCe{sub 0.1}Co{sub x}Fe{sub 0.9-x}O{sub 3-{delta}} membranes gradually increases with testing time in the initial stage, and the time to reach steady state becomes longer with the increase of cobalt content. After reaching permeation steady state, BaCe{sub 0.1}Co{sub 0.4}Fe{sub 0.5}O{sub 3-{delta}} exhibits highest oxygen flux amongst BaCe{sub 0.1}Co{sub x}Fe{sub 0.9-x}O{sub 3-{delta}} series.

  17. Adsorption of Ba2+ by Ca-exchange clinoptilolite tuff and montmorillonite clay.

    PubMed

    Chávez, M L; de Pablo, L; García, T A

    2010-03-15

    The adsorption of barium by Ca-exchanged clinoptilolite and montmorillonite is presented. The kinetics of adsorption of Ba(2+) were evaluated contacting 1g portion of each adsorber with 100mL 0.1N BaCl(2) for 200 h. Adsorption by Ca-clinoptilolite is defined by second-order kinetics of rate constant K(v) 8.232 x 10(-2) g mg(-1)h(-1) and maximum removal of 71.885 mg g(-1). It is a two-stage process initiated by a rapid uptake of Ba(2+) followed by more moderate kinetics. The adsorption isotherms were determined contacting 0.2g of each adsorber with 10 mL 0.1-0.005N BaCl(2)+CaCl(2) solution, Ba(2+)/Ca(2+) ratio 1, for periods of 7 days for the tuff and 2 days for the clay. The equilibrium adsorption is described by the Langmuir model, of equilibrium constant K 0.0151 L mg(-1) and maximum adsorption of 15.29 mg g(-1). The adsorption of Ba(2+) by Ca-exchanged montmorillonite also follows a second-order reaction of rate constant K(v) 3.179 x 10(-2) g mg(-1)h(-1), and calculated separation of 36.74 mg g(-1); the Langmuir isotherm is defined by the constant K 0.034 L mg(-1) and maximum adsorption of 15.29 mg g(-1). X-ray diffraction shows that the exchange of Ba(2+) modifies the d(001) of Ca-montmorillonite from 15.4 to 12.4A. PMID:19926210

  18. Jumping the gun: Smoking constituent BaP causes premature primordial follicle activation and impairs oocyte fusibility through oxidative stress

    SciTech Connect

    Sobinoff, A.P.; Pye, V.; Nixon, B.; Roman, S.D.; McLaughlin, E.A.

    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.

  19. Anomalous Ba/Ca signals associated with low temperature stresses in Porites corals from Daya Bay, northern South China Sea.

    PubMed

    Chen, Tianran; Yu, Kefu; Li, Shu; Chen, Tegu; Shi, Qi

    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.

  20. Synthesis and Characterization of a Series of Quaternary Chalcogenides Ba LnMQ3 ( Ln=Rare Earth, M=Coinage Metal, Q=Se or Te)

    NASA Astrophysics Data System (ADS)

    Yang, Yuting; Ibers, James A.

    1999-10-01

    The compounds BaGdAuSe3, BaLaCuTe3, BaYCuTe3, BaYAgTe3, BaLaAgTe3, BaYbCuTe3, BaGdAgTe3, BaNdCuTe3, and BaPrCuTe3 were prepared by the reaction in a BaBr2/KBr flux at 850°C of a rare earth, a coinage-group metal, a chalcogen, and BaSe or BaTe. The unit cells of all of the compounds and the crystal structures of the first four compounds were determined by single-crystal X-ray diffraction methods. With the exception of BaLaCuTe3, which crystallizes with four formula units in the orthorhombic space group Pnma, all of these compounds crystallize with four formula units in the orthorhombic space group Cmcm. BaLaCuTe3, isostructural with β-BaLaCuSe3 and Eu2CuS3 (i.e., Eu2+Eu3+Cu+(S2-)3), and BaGdAuSe3, BaYCuTe3, and BaYAgTe3, isostructural with KZrCuS3, crystallize in a layered structure in which there are 2∞[LnMQ2-3] layers separated by Ba2+ ions. Ln atoms are coordinated by six Q atoms at the corners of a distorted octahedron, and M atoms are coordinated by four Q atoms at the corners of a tetrahedron. The layers are formed by the connection of edge-sharing octahedral chains and corner-sharing tetrahedral chains. Ba atoms are coordinated by seven Q atoms in BaLaCuTe3 and by eight Q atoms in BaGdAuSe3, BaYCuTe3, and BaYAgTe3. BaNdAgTe3 shows temperature-dependent paramagnetism. Its magnetic susceptibility follows the Curie-Weiss law. The effective magnetic moment of 3.4(3) μB is in agreement with the theoretical value of 3.6 μB for Nd3+.

  1. Work Function Reduction by BaO: Growth of Crystalline Barium Oxide on Ag(001) and Ag(111) Surfaces

    SciTech Connect

    Droubay, Timothy C.; Kong, Lingmei; Chambers, Scott A.; Hess, Wayne P.

    2015-02-01

    Ultrathin films of barium oxide were grown on Ag(001) and Ag(111) using the evaporation of Ba metal in an O2 atmosphere by molecular beam epitaxy. Ultraviolet photoemission spectroscopy reveals that films consisting of predominantly BaO or BaO2 result in Ag(001) work function reductions of 1.74 eV and 0.64 eV, respectively. On the Ag(001) surface, Ba oxide growth is initiated by two-dimensional nucleation of epitaxial BaO, followed by a transition to three-dimensional dual-phase nucleation of epitaxial BaO and BaO2. Three-dimensional islands of primarily BaO2(111) nucleate epitaxially on the Ag(111) substrate leaving large patches of Ag uncovered. We find no indication of chemical reaction or charge transfer between the films and the Ag substrates. These data suggest that the origin of the observed work function reduction is largely due to a combination of BaO surface relaxation and an electrostatic compressive effect.

  2. Rapid chemical synthesis of the barium ferrate super-iron Fe (VI) compound, BaFeO 4

    NASA Astrophysics Data System (ADS)

    Licht, Stuart; Naschitz, Vera; Wang, Baohui

    An alternate rapid synthesis of BaFeO 4 is demonstrated. Fe(VI) salts, including BaFeO 4, are energetic cathode materials in super-iron batteries ranging from primary to secondary, and including aqueous and non-aqueous cells. Of the Fe(VI) salts, BaFeO 4 sustains unusually facile charge transfer, of importance to the high power domain of alkaline batteries. Unlike previous syntheses, BaFeO 4 preparation is demonstrated from all solid state room temperature reactants. This eliminates several synthetic procedural steps and improves stability to approach that of the rigorously stable chemically synthesized K 2FeO 4 salt.

  3. Magnetic and transport properties of some Ln-Ba-Cu-O (Ln=Yb, Tm, Sm) superconducting oxides

    NASA Astrophysics Data System (ADS)

    Marcus, J.; Escribe-Filippini, C.; Schlenker, C.; Buder, R.; Devenyi, J.; Reydet, P. L.

    1987-07-01

    Powders of Yb-Ba-Cu-O, Tm-Ba-Cu-O and Sm-Ba-Cu-O have been synthetized. Electrical resistivity and magnetic susceptibility measurements show that they are superconducting with onset transition temperatures in the range 91 K - 85 K. The thermopower, in these oxides as well as in Sr xLa 2-xCuO 4-δ and Ba 2YCu 3O 7-δ, is found to be positive between T c and 300 K. Hysteresis of the diamagnetic magnetization is also reported.

  4. Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2.

    PubMed

    Liu, Jinyu; Hu, Jin; Cao, Huibo; Zhu, Yanglin; Chuang, Alyssa; Graf, D; Adams, D J; Radmanesh, S M A; Spinu, L; Chiorescu, I; Mao, Zhiqiang

    2016-01-01

    Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm(2)V(-1)S(-1)) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons. PMID:27466151

  5. Large linear magnetoresistance in a new Dirac material BaMnBi2

    NASA Astrophysics Data System (ADS)

    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).

  6. Surface structures and growth modes of Ba deposited on Mo(110) surface

    NASA Astrophysics Data System (ADS)

    Jo, S.; Gotoh, Y.

    2000-10-01

    The surface structures and growth modes of barium (Ba) on an Mo(110) surface have been investigated using a molecular beam epitaxy system equipped with a high-energy electron diffraction (RHEED) apparatus. Three kinds of surface structures were observed, c(2×2), (1.6×2) and (1.5×1.8), in regions with low Ba coverage, and their phase diagram was obtained. All Ba atoms which form the c(2×2) structure coincide with Mo atoms, and the (1.6×2) and (1.5×1.8) structures with the regular triangle lattice have line coincidences with the atomic arrangement of the substrate along the [11¯0]Mo and [001]Mo directions, respectively. In the thickness range beyond 1 ML, the growth modes of the Ba-Mo(110) system were different due to the substrate temperature. The growth of the Ba-Mo(110) system is in accordance with the Frank-van der Merwe growth mode at room temperature and the Stranski-Krastanov growth mode at high temperatures.

  7. Hybrid molecular beam epitaxy for the growth of stoichiometric BaSnO{sub 3}

    SciTech Connect

    Prakash, Abhinav Dewey, John; Yun, Hwanhui; Jeong, Jong Seok; Mkhoyan, K. Andre; Jalan, Bharat

    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}.

  8. Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2

    PubMed Central

    Liu, Jinyu; Hu, Jin; Cao, Huibo; Zhu, Yanglin; Chuang, Alyssa; Graf, D.; Adams, D. J.; Radmanesh, S. M. A.; Spinu, L.; Chiorescu, I.; Mao, Zhiqiang

    2016-01-01

    Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm2V−1S−1) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons. PMID:27466151

  9. BaTiO3 and polypropylene nanocomposites for capacitor applications

    NASA Astrophysics Data System (ADS)

    Dong, Daxuan; Tang, Longxiang; Zhu, Lei; Lee, Je; Case Western Reserve University Collaboration; Agiltron, Inc Collaboration

    2013-03-01

    A novel strategy to uniformly disperse 70-nm BaTiO3 ferroelectric nanoparticles in a dielectric polypropylene (PP) matrix is developed in order to achieve high dielectric constant and high energy density for capacitor applications. By modifying BaTiO3 surface with a bis-phosphonic acid-terminated polyhedral oligomeric selsisquioxane (POSS), a nanocomposite with BaTiO3@POSS uniformly dispersed in PP matrix was achieved. The nanocomposite film containing a high nanoparticle content of 30 vol.% exhibited a high dielectric constant of 32 and a breakdown voltage of 220 MV/m, but with a high energy loss. Improvement of this nanocomposite by understanding the interfacial polarization is carried out in this work. The dielectric constant difference between BaTiO3 and PP can generate interfacial polarization and subsequent internal conduction in BaTiO3 particles upon bipolar polarization. Reduction of this internal conduction mechanism will significantly reduce the hysteresis loss in polymer nanodielectrics.

  10. Size dependent magnetic and electrical properties of Ba-doped nanocrystalline BiFeO3

    NASA Astrophysics Data System (ADS)

    Hasan, Mehedi; Hakim, M. A.; Basith, M. A.; Hossain, Md. Sarowar; Ahmmad, Bashir; Zubair, M. A.; Hussain, A.; Islam, Md. Fakhrul

    2016-03-01

    Improvement in magnetic and electrical properties of multiferroic BiFeO3 in conjunction with their dependence on particle size is crucial due to its potential applications in multifunctional miniaturized devices. In this investigation, we report a study on particle size dependent structural, magnetic and electrical properties of sol-gel derived Bi0.9Ba0.1FeO3 nanoparticles of different sizes ranging from ˜ 12 to 49 nm. The substitution of Bi by Ba significantly suppresses oxygen vacancies, reduces leakage current density and Fe2+ state. An improvement in both magnetic and electrical properties is observed for 10 % Ba-doped BiFeO3 nanoparticles compared to its undoped counterpart. The saturation magnetization of Bi0.9Ba0.1FeO3 nanoparticles increase with reducing particle size in contrast with a decreasing trend of ferroelectric polarization. Moreover, a first order metamagnetic transition is noticed for ˜ 49 nm Bi0.9Ba0.1FeO3 nanoparticles which disappeared with decreasing particle size. The observed strong size dependent multiferroic properties are attributed to the complex interaction between vacancy induced crystallographic defects, multiple valence states of Fe, uncompensated surface spins, crystallographic distortion and suppression of spiral spin cycloid of BiFeO3.

  11. Ba4Ga2Se8: A ternary selenide containing chains and discrete Se22- units

    NASA Astrophysics Data System (ADS)

    Yin, Wenlong; Iyer, Abishek K.; Lin, Xinsong; Mar, Arthur

    2016-05-01

    The ternary selenide Ba4Ga2Se8 has been synthesized by reaction of BaSe, Ga2Se3, and Se at 1023 K. Single-crystal X-ray diffraction analysis revealed a monoclinic structure (space group P21/c, Z=4, a=13.2393(5) Å, b=6.4305(2) Å, c=20.6432(8) Å, β=104.3148(6)°) featuring one-dimensional chains of corner-sharing Ga-centered tetrahedra and discrete Se22- anionic units, with charge-compensating Ba2+ cations located between them. The UV/vis/NIR diffuse reflectance spectrum reveals an optical band gap of 1.63(2) eV, which is consistent with the black color of the crystals and agrees with a calculated gap of 1.51 eV obtained from band structure calculations. The presence of the Se22- units narrows the band gap in Ba4Ga2Se8 relative to other Ba-Ga-Se phases.

  12. Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2

    NASA Astrophysics Data System (ADS)

    Liu, Jinyu; Hu, Jin; Cao, Huibo; Zhu, Yanglin; Chuang, Alyssa; Graf, D.; Adams, D. J.; Radmanesh, S. M. A.; Spinu, L.; Chiorescu, I.; Mao, Zhiqiang

    2016-07-01

    Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0 m0, mass of free electron), high quantum mobility (1280 cm2V‑1S‑1) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons.

  13. Study of Ba and Zr stability in UO2±x by density functional calculations

    NASA Astrophysics Data System (ADS)

    Brillant, G.; Pasturel, A.

    2008-05-01

    Barium and zirconium behavior in nuclear fuels is investigated using density functional theory (DFT). More particularly, incorporation and solution energies of Ba and Zr in preexisting trap sites of UO2 (vacancies, interstitials, U-O divacancy, and Schottky trio defects) are calculated using the projector-augmented-wave method as implemented in the Vienna ab initio simulation package (VASP). Correlation effects are taken into account within the DFT+U approach. Our results are discussed in relation to those based on conventional functionals and with available experimental data. For both functionals, zirconium is found to be much more soluble than barium. However, the most favorable solution site depends on the treatment of correlation effects, the difference between DFT+U and DFT based results being more pronounced for Zr than for Ba. We also demonstrate that the solution process for more complex phases like BaO, ZrO2 , BaUO3 , and BaZrO3 are very sensitive to the correct description of correlation effects in UO2 .

  14. Magnetic and magnetocaloric properties of Ba and Ti co-doped SrRuO3

    NASA Astrophysics Data System (ADS)

    Sarkar, Babusona; Dalal, Biswajit; Dev Ashok, Vishal; De, S. K.

    2014-12-01

    Temperature evolution of magnetic properties in Ba and Ti doped SrRuO3 has been investigated to observe the effects of larger ionic radius Ba at Sr site and isovalent nonmagnetic impurity Ti at Ru site. Ionic radius mismatch and different electronic configuration in comparison with Ru modify Sr(Ba)-O and Ru(Ti)-O bond lengths and Ru-O-Ru bond angle. The apical and basal Ru-O-Ru bond angles vary significantly with Ti doping. Ferromagnetic Curie temperature decreases from 161 K to 149 K monotonically with Ba (10%) and Ti (10%) substitutions at Sr and Ru sites. The zero field cooled (ZFC) magnetization reveals a prominent peak which shifts towards lower temperature with application of magnetic field. The substitution of tetravalent Ti with localized 3d0 orbitals for Ru with more delocalized 4d4 orbitals leads to a broad peak in ZFC magnetization. A spontaneous ZFC magnetization becomes negative below 160 K for all the compositions. The occurrence of both normal and inverse magnetocaloric effects in Ba and Ti co-doped SrRuO3 makes the system more interesting.

  15. [Research on the degradation of BaP with potassium ferrate characterized by fluorescence].

    PubMed

    Chen, Yu-Zhe; He, Qiang; Yu, Dan-Ni; Li, Si; Tan, Xue-Mei

    2012-07-01

    The degradation of Benzo(a)pyrene (BaP) by potassium ferrate was researched by means of multiple fluorescence spectroscopic methods such as synchronous, time-scan, excitation emission matrix (EEM) and photometry, under the optimal condition. Within the degradation process, the characteristics of the BaP's concentration at different time-intervals, and the kinetics of the degradation of BaP by potassium ferrate were discussed. From the experimental data, both synchronous and EEM spectra's results showed that the concentration of BaP was reduced 90% by potassium ferrate within 20 s after degradation, and the reaction process was very slow after 60 s. The degradation kinetic equation, ln(F0/Ft) = 0.563 2t + 0.171 2, (R2 = 0.994 2), was obtained through a convenient and fast way combining the time-scan fluorescence data and photometry data, and the photometry included the synchronous photometry and emission photometry. According to the kinetic equation, the degradation of BaP by potassium ferrate was in accord with the order of the first order reaction. So this article could provide a very useful conference for the research on the pollutant degradation by potassium ferrate, especially for the degradation process and the degradation mechanisms.

  16. Sintering and Microstructure of BaTiO3 Nano Particles Synthesized by Molten Salt Method.

    PubMed

    Lee, Chang-Hyun; Shin, Hyo-Soon; Yeo, Dong-Hun; Ha, Gook-Hyun; Nahm, Sahn

    2016-05-01

    In order to establish thinner dielectric layers in thick film electronic components such as MLCC (Multilayer ceramic capacitor), BaTiO3 nanoparticles have been utilized. However, studies on the synthesis of nanoparticles smaller than 20 nm, the characteristics of the BaTiO3 powder, and the powder's sintering are lacking. Therefore, this paper aims to synthesize BaTiO3 particles smaller than 20 nm by using the molten salt method and evaluate the microstructure and dielectric properties by varying the sintering temperature from 750 degrees C to 1200 degrees C. Through the molten salt method and by using KOH-KCl mixed salt, 20 nm BaTiO3 powder was synthesized at a low temperature of 150 degrees C. Sintering the pellets formed from the synthesized 20 nm BaTiO3 nano powder led to the observation of an unusual phenomenon where the particles grew to approximate sizes below 850 degrees C where densification progressed. At sintering temperatures above 950 degrees C, particles that expanded into rod shapes were observed and these particles were identified to be unreacted TiO2 based on the results of the EDX (Energy Dispersive X-ray Spectroscopy) analysis and phase analysis results.

  17. Synthesis and Microwave Absorption Properties of BaTiO3-polypyrrole Composite

    NASA Astrophysics Data System (ADS)

    Li, Qiao-ling; Zhang, Cun-rui; Li, Jian-qiang

    2010-10-01

    BaTiO3 powders are prepared by sol-gel method by cotton template. Polypyrrole is prepared by chemical oxidation route in the emulsion polymerization system. Then BaTiO3-polypyrrole composites with different mixture ratios are prepared by as-prepared material. The structure, morphology, and properties of the composites are characterized with Infrared spectrum, X-ray diffraction, scanning electron microscope, and net-wok analyzer. The complex permittivity and reflection loss of the composites are measured at different microwave frequencies in S-band and C-band (0.03-6 GHz) employing vector network analyzer model PNA 3629D vector. The effect of the mass ratio of BaTiO3 to polypyrrole on the microwave loss properties of the composites is investigated. A possible microwave absorbing mechanism of BaTiO3-polypyrrole composite is proposed. The BaTiO3-polypyrrole composite can find applications in suppression of electromagnetic interference and reduction of radar signature.

  18. Structure investigation with the (p,t) reaction on {sup 132,134}Ba nuclei

    SciTech Connect

    Pascu, S.; Cata-Danil, Gh.; Bucurescu, D.; Marginean, N.; Zamfir, N. V.; Mueller, C.; Graw, G.; Gollwitzer, A.; Hofer, D.; Valnion, B. D.

    2010-01-15

    The low-lying excited states in {sup 132,134}Ba isotopes have been studied with high-resolution (p,t) reactions. The experiments were performed at the Munich Q3D spectrograph with a 25-MeV proton beam and the 1.5-m-long focal plane detector. The high-resolution triton spectra allowed the observation of levels up to {approx}4 MeV. The experimental results revealed 75 excited states in {sup 134}Ba and 79 in {sup 132}Ba, many of them observed for the first time. The measured angular distributions compared with distorted-wave Born approximation calculations allowed spin assignments for these levels in most cases. The systematics of the monopole and quadrupole two-neutron transfer strengths is compared with the prediction of the interacting boson approximation model. The results indicate a transitional structure in {sup 132}Ba and {sup 134}Ba and contribute additional evidence in favor of a description between the U(5) and O(6) symmetries of the model.

  19. Investigation of the {sup 128}Ba nucleus with the (p,t) reaction

    SciTech Connect

    Pascu, S.; Cata-Danil, Gh.; Bucurescu, D.; Marginean, N.; Zamfir, N. V.; Graw, G.; Gollwitzer, A.; Hofer, D.; Valnion, B. D.

    2009-06-15

    The low lying states in {sup 128}Ba have been investigated for the first time with the {sup 130}Ba(p,t){sup 128}Ba reaction. The experiment was performed at the Munich Q3D magnetic spectrograph with a 25-MeV proton beam and a high-resolution, 1.5-m-long focal plane detector. As a result of this experiment 27 excited levels with energies below 3.7 MeV have been observed for the first time, significantly increasing (by {approx}50%) the number of levels observed in {sup 128}Ba. Angular distributions of tritons were measured and their comparison with the distorted wave Born approximation calculation allowed in most cases spin and parity assignments for the nuclear levels. The experimental two-neutron transition strengths with transferred angular momentum L=0 and 2 are compared with the predictions of the IBA-1 model with a new set of parameters. The results indicate for the first time from a hadronic probe perspective a transitional structure close to the O(6) symmetry for the {sup 128}Ba nucleus, confirming previous conclusions of {gamma}-ray spectroscopy studies.

  20. Microstructure and Cs Behavior of Ba-Doped Aluminosilicate Pollucite Irradiated with F+ Ions

    SciTech Connect

    Jiang, Weilin; Kovarik, Libor; Zhu, Zihua; Varga, Tamas; Engelhard, Mark H.; Bowden, Mark E.; Nenoff, Tina M.; Garino, Terry

    2014-06-24

    Radionuclide 137Cs is one of the major fission products that dominate heat generation in spent fuels over the first 300 hundred years. A durable waste form for 137Cs that decays to 137Ba is needed to minimize its environmental impact. Aluminosilicate pollucite CsAlSi2O6 is selected as a model waste form to study the decay-induced structural effects. While Ba-containing precipitates are not present in charge-balanced Cs0.9Ba0.05AlSi2O6, they are found in Cs0.9Ba0.1AlSi2O6 and identified as monoclinic Ba2Si3O8. Pollucite is susceptible to electron irradiation induced amorphization. The threshold density of the electronic energy deposition for amorphization is determined to be ~235 keV/nm3. Pollucite can be readily amorphized under F+ ion irradiation at 673 K. A significant amount of Cs diffusion and release from the amorphized pollucite is observed during the irradiation. However, cesium is immobile in the crystalline structure under He+ ion irradiation at room temperature. The critical temperature for amorphization is not higher than 873 K under F+ ion irradiation. If kept at or above 873 K all the time, the pollucite structure is unlikely to be amorphized; Cs diffusion and release are improbable. A general discussion regarding pollucite as a potential waste form is provided in this report.

  1. Lattice dynamics of BaFe2X3(X=S,Se) compounds

    DOE PAGES

    Popović, Z. V.; Šćepanović, M.; Lazarević, N.; Opačić, M.; Radonjić, M. M.; Tanasković, D.; Lei, Hechang; Petrovic, C.

    2015-02-27

    We present the Raman scattering spectra of the S=2 spin ladder compounds BaFe₂X₃ (X=S,Se) in a temperature range between 20 and 400 K. Although the crystal structures of these two compounds are both orthorhombic and very similar, they are not isostructural. The unit cell of BaFe₂S₃ (BaFe₂Se₃) is base-centered Cmcm (primitive Pnma), giving 18 (36) modes to be observed in the Raman scattering experiment. We have detected almost all Raman active modes, predicted by factor group analysis, which can be observed from the cleavage planes of these compounds. Assignment of the observed Raman modes of BaFe₂S(Se)₃ is supported by themore » lattice dynamics calculations. The antiferromagnetic long-range spin ordering in BaFe₂Se₃ below TN=255K leaves a fingerprint both in the A1g and B3g phonon mode linewidth and energy.« less

  2. Precipitation method for barium metaborate (BaB2O4) synthesis from borax solution

    NASA Astrophysics Data System (ADS)

    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.

  3. Functional magnetic resonance imaging connectivity analyses reveal efference-copy to primary somatosensory area, BA2.

    PubMed

    Cui, Fang; Arnstein, Dan; Thomas, Rajat Mani; Maurits, Natasha M; Keysers, Christian; Gazzola, Valeria

    2014-01-01

    Some theories of motor control suggest efference-copies of motor commands reach somatosensory cortices. Here we used functional magnetic resonance imaging to test these models. We varied the amount of efference-copy signal by making participants squeeze a soft material either actively or passively. We found electromyographical recordings, an efference-copy proxy, to predict activity in primary somatosensory regions, in particular Brodmann Area (BA) 2. Partial correlation analyses confirmed that brain activity in cortical structures associated with motor control (premotor and supplementary motor cortices, the parietal area PF and the cerebellum) predicts brain activity in BA2 without being entirely mediated by activity in early somatosensory (BA3b) cortex. Our study therefore provides valuable empirical evidence for efference-copy models of motor control, and shows that signals in BA2 can indeed reflect an input from motor cortices and suggests that we should interpret activations in BA2 as evidence for somatosensory-motor rather than somatosensory coding alone.

  4. Functional Magnetic Resonance Imaging Connectivity Analyses Reveal Efference-Copy to Primary Somatosensory Area, BA2

    PubMed Central

    Cui, Fang; Arnstein, Dan; Thomas, Rajat Mani; Maurits, Natasha M.; Keysers, Christian; Gazzola, Valeria

    2014-01-01

    Some theories of motor control suggest efference-copies of motor commands reach somatosensory cortices. Here we used functional magnetic resonance imaging to test these models. We varied the amount of efference-copy signal by making participants squeeze a soft material either actively or passively. We found electromyographical recordings, an efference-copy proxy, to predict activity in primary somatosensory regions, in particular Brodmann Area (BA) 2. Partial correlation analyses confirmed that brain activity in cortical structures associated with motor control (premotor and supplementary motor cortices, the parietal area PF and the cerebellum) predicts brain activity in BA2 without being entirely mediated by activity in early somatosensory (BA3b) cortex. Our study therefore provides valuable empirical evidence for efference-copy models of motor control, and shows that signals in BA2 can indeed reflect an input from motor cortices and suggests that we should interpret activations in BA2 as evidence for somatosensory-motor rather than somatosensory coding alone. PMID:24416222

  5. Structural and electrical transport properties of proficient Ba-Pb nanoferrites

    NASA Astrophysics Data System (ADS)

    Haq, A.; Anis-ur-Rehman, M.; Malik, Muhammad Ali

    2012-03-01

    The excellent combination of magnetic and dielectric properties of hexaferrites makes these materials suitable for use in high-frequency applications. Ba-Pb nanocrystalline ferrites having the general formula Ba1-xPbxFe12O19 (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were prepared by the co-precipitation method. X-ray powder diffraction (XRD) patterns of all prepared samples indicated the formation of the required phase. The crystallite size, lattice parameters and porosities of samples were measured from XRD data. Scanning electron microscopy was carried out to observe the morphology of the synthesized Ba-Pb ferrites. Temperature-dependent dc electrical resistivity, dielectric constant, dielectric loss tangent and the ac electrical conductivity of nanocrystalline Ba ferrites were investigated as a function of frequency and Pb concentration. The effect of Pb doping on dielectric and electric properties of Ba nanoferrites was explained on the basis of cation distribution in the crystal structure.

  6. Significant increase of Curie temperature in nano-scale BaTiO3

    NASA Astrophysics Data System (ADS)

    Li, Yueliang; Liao, Zhenyu; Fang, Fang; Wang, Xiaohui; Li, Longtu; Zhu, Jing

    2014-11-01

    The low Curie temperature (Tc = 130 °C) of bulk BaTiO3 greatly limits its applications. In this work, the phase structures of BaTiO3 nanoparticles with sizes ranging from 2.5 nm to 10 nm were studied at various temperatures by using aberration-corrected transmission electron microscopy (TEM) equipped with an in-situ heating holder. The results implied that each BaTiO3 nanoparticle was composed of different phases, and the ferroelectric ones were observed in the shells due to the complicated surface structure. The ferroelectric phases in BaTiO3 nanoparticles remained at 600 °C, suggesting a significant increase of Tc. Based on the in-situ TEM results and the data reported by others, temperature-size phase diagrams for BaTiO3 particles and ceramics were proposed, showing that the phase transition became diffused and the Tc obviously increased with decreasing size. The present work sheds light on the design and fabrication of advanced devices for high temperature applications.

  7. Significant increase of Curie temperature in nano-scale BaTiO{sub 3}

    SciTech Connect

    Li, Yueliang; Liao, Zhenyu; Fang, Fang; Zhu, Jing; Wang, Xiaohui; Li, Longtu

    2014-11-03

    The low Curie temperature (T{sub c} = 130 °C) of bulk BaTiO{sub 3} greatly limits its applications. In this work, the phase structures of BaTiO{sub 3} nanoparticles with sizes ranging from 2.5 nm to 10 nm were studied at various temperatures by using aberration-corrected transmission electron microscopy (TEM) equipped with an in-situ heating holder. The results implied that each BaTiO{sub 3} nanoparticle was composed of different phases, and the ferroelectric ones were observed in the shells due to the complicated surface structure. The ferroelectric phases in BaTiO{sub 3} nanoparticles remained at 600 °C, suggesting a significant increase of T{sub c}. Based on the in-situ TEM results and the data reported by others, temperature-size phase diagrams for BaTiO{sub 3} particles and ceramics were proposed, showing that the phase transition became diffused and the T{sub c} obviously increased with decreasing size. The present work sheds light on the design and fabrication of advanced devices for high temperature applications.

  8. Calculation of B/A for n-alkane liquids using the Tait equation

    PubMed

    Hartmann; Lee; Balizer

    2000-07-01

    The B/A parameter of acoustic nonlinearity was calculated for a series of n-alkane liquids using the Tait PVT equation of state supplemented with specific heat data. The calculations of sound speed, sound speed derivatives, the two components of B/A, and the value of B/A itself were compared with experimental data taken from the literature and with earlier calculations using a different equation of state. In addition, a comparison of the results with Ballou's rule (linear relation of B/A and reciprocal sound speed) was made. It is concluded that B/A can be calculated from the Tait equation of state with about the same accuracy as direct measurements of sound speed versus pressure and temperature, though the the temperature derivatives of the sound speed are calculated with much lower accuracy than pressure derivatives. The calculations made using the Tait equation are about the same accuracy as calculations made using our equation of state. Also, Ballou's rule does not hold for these liquids. PMID:10923871

  9. Thermoluminescence studies of bismuth doped Ba xCa 1- xS nanostructures

    NASA Astrophysics Data System (ADS)

    Singh, Surender; Lochab, S. P.; Kumar, Ravi; Singh, Nafa

    2011-01-01

    Bismuth doped Ba 1- xCa xS:Bi ( x=0-1) nanocrystallities have been prepared by the solid state reaction method and characterized by XRD and TEM. X-ray diffraction analysis shows the formation of the compounds in cubic structure at room temperature. Only partial replacement of Ba is possible and we found that Ba 0.5Ca 0.5S:Bi could not be prepared due to the difference between ionic radii of barium and calcium. Thermoluminescence studies of these samples after exposure to UV radiation have been carried out. The TL glow curve of Ba xCa 1 -xS:Bi has been found to be a simple structure with a single peak at 405, 428 and 503 K for x=1, 0.8 and 0, respectively. The kinetic parameters at various heating rates namely activation energy ( E), order of kinetics ( b) and frequency factor ( s) of the Ba 1- xCa xS:Bi ( x=0.2) (0.4 mol%) sample have been determined using Chen’s method. The deconvolution of curve was done using the GCD function suggested by Kitis. The effect of different heating rates and different amount of dose has also been discussed.

  10. Antiperovskite Chalco-Halides Ba3(FeS4)Cl, Ba3(FeS4)Br, and Ba3(FeSe4)Br with Spin Super-Super Exchange

    PubMed Central

    Zhang, Xian; Liu, Kai; He, Jian-Qiao; Wu, Hui; Huang, Qing-Zhen; Lin, Jian-Hua; Lu, Zhong-Yi; Huang, Fu-Qiang

    2015-01-01

    Perovskite-related materials have received increasing attention for their broad applications in photovoltaic solar cells and information technology due to their unique electrical and magnetic properties. Here we report three new antiperovskite chalco-halides: Ba3(FeS4)Cl, Ba3(FeS4)Br, and Ba3(FeSe4)Br. All of them were found to be good solar light absorbers. Remarkably, although the shortest Fe-Fe distance exceeds 6 Å, an unexpected anti-ferromagnetic phase transition near 100 K was observed in their magnetic susceptibility measurement. The corresponding complex magnetic structures were resolved by neutron diffraction experiments as well as investigated by first-principles electronic structure calculations. The spin-spin coupling between two neighboring Fe atoms along the b axis, which is realized by the Fe-S···S-Fe super-super exchange mechanism, was found to be responsible for this magnetic phase transition. PMID:26525136

  11. Mitochondrial dysfunction and transactivation of p53-dependent apoptotic genes in BaP-treated human fetal lung fibroblasts.

    PubMed

    Yang, Guangtao; Jiang, Ying; Rao, Kaimin; Chen, Xi; Wang, Qian; Liu, Ailin; Xiong, Wei; Yuan, Jing

    2011-12-01

    Benzo(a)pyrene (BaP) has been shown to be an inducer of apoptosis. However, mechanisms involved in BaP-induced mitochondrial dysfunction are not well-known. In this study, human fetal lung fibroblasts cells were treated with BaP (8, 16, 32, 64 and 128 μM) for 4 and 12 h. Cell viability, intracellular level of reactive oxygen species (ROS), total antioxidant capacity (T-AOC), mitochondrial membrane potential (ΔΨ(m)) and cytochrome c release were determined. Changes in transcriptional levels of p53-dependent apoptotic genes (p53, APAF1, CASPASE3, CASPASE9, NOXA and PUMA) were measured. At time point of 4 h, BaP induced the intracellular ROS generation in 64 (p < .05) and 128 μM BaP groups (p < .01) but decreased the T-AOC activities in 32, 64 (p < .05 for both) and 128 μM BaP groups (p < .01). At time point of 12 h, ΔΨ(m) significantly decreased in ≥32 μM BaP groups (p < .05 for all). Amount of mitochondrial cytochrome c significantly increased in 128 μM BaP group (p < .01). Transcriptional levels of CASPASE3, CASPASE9, APAF1 and PUMA were up-regulated in all BaP groups (p < .05 for all) and in ≥32 μM groups for NOXA (p < .05). But only in 16 μM BaP group a relatively little expression of p53 mRNA was observed (p < .05). The results indicate that in the earlier period BaP promoted the generation of excessive ROS and subsequently the mitochondrial depolarization, whereas transactivations of the p53-dependent apoptotic genes were significantly induced at the later period.

  12. Reactive two-body and three-body collisions of Ba+ in an ultracold Rb gas

    NASA Astrophysics Data System (ADS)

    Krükow, Artjom; Mohammadi, Amir; Härter, Arne; Hecker Denschlag, Johannes

    2016-09-01

    We analyze reactive collisions of a single Ba+ ion in contact with an ultracold gas of Rb atoms at low three-body collision energies of 2.2(9) mK ×kB . Mapping out the Ba+ loss rate dependence on the Rb atom density we can discern two-body reactive collisions from three-body ones and determine both rate coefficients, which are k2=3.1 (6 ) (6 ) ×10-13cm3s-1 and k3=1.04 (4 ) (45 ) ×10-24cm6s-1 , respectively (statistical and systematic errors in parentheses). Thus, the measured ternary recombination dominates over binary reactions even at moderate atom densities of n ≈1012cm-3 . The results for Ba+ and Rb are representative for a wide range of cold ion-atom systems and can serve as guidance for the future development of the field of hybrid atom-ion research.

  13. Spectroscopic and theoretical studies of the low-lying states of BaO{sup +}

    SciTech Connect

    Bartlett, Joshua H.; VanGundy, Robert A.; Heaven, Michael C.

    2015-07-28

    The BaO{sup +} cation is of interest from the perspectives of electronic structure and the potential for cooling to ultra-cold temperatures. Spectroscopic data for the ion have been obtained using a two-color photoionization technique. The ionization energy for BaO was found to be 6.8123(3) eV. The ground state of BaO{sup +} was identified as X{sup 2}Σ{sup +}, and both vibrational and rotational constants were determined. Vibrationally resolved spectra were recorded for A{sup 2}Π, the first electronically excited state. These data yielded the term energy, vibrational frequency, and the spin-orbit interaction constant. Relativistic electronic structure calculations were carried out using multi-reference configuration interaction (MRCI), coupled cluster and density functional theory methods. Transition moments for the pure vibrational and A{sup 2}Π-X{sup 2}Σ{sup +} transitions were predicted using the MRCI method.

  14. Superconductivity and structural distortion in BaPt2As2.

    PubMed

    Jiang, W B; Guo, C Y; Weng, Z F; Wang, Y F; Chen, Y H; Chen, Y; Pang, G M; Shang, T; Lu, X; Yuan, H Q

    2015-01-21

    We report the synthesis of BaPt2As2 single crystals and the discovery of superconductivity and a structural phase transition in this compound by measuring the electrical resistivity, magnetic susceptibility and specific heat as well as the x-ray diffraction at low temperatures. BaPt2As2 crystallizes in the CaBe2Ge2-type tetragonal structure (P4/nmm) at room temperature and undergoes a first-order structural transition at TS ≃ 275 K, which is likely to be associated with a charge-density-wave (CDW) instability. BCS-like superconductivity with two subsequent transitions Tc1 ≃ 1.67 K and Tc2 ≃ 1.33 K is observed. Our results demonstrate that BaPt2As2 may serve as a new system for studying the interplay of superconductivity and the CDW order.

  15. Pseudogap and anharmonic phonon behavior in Ba8Ga16Ge30: An NMR study

    NASA Astrophysics Data System (ADS)

    Sirusi, Ali A.; Ross, Joseph H.

    2016-08-01

    We have performed 69Ga, 71Ga, and 137Ba NMR on Ba8Ga16Ge30, a clathrate semiconductor which has been of considerable interest due to its large figure of merit for thermoelectric applications. In measurements from 4 K to 450 K, we used measurements on the two Ga nuclei to separate the magnetic and electric quadrupole hyperfine contributions and thereby gain information about the metallic and phonon behavior. The results show the presence of a pseudogap in the Ga electronic states within the conduction band, superposed upon a large Ba contribution to the conduction band. Meanwhile the phonon contributions to the Ga relaxation rates are large and increase more rapidly with temperature than typical semiconductors. These results provide evidence for enhanced anharmonicity of the propagative phonon modes over a wide range, providing experimental evidence for enhanced phonon-phonon scattering as a mechanism for the reduced thermal conductivity.

  16. A General Reliability Model for Ni-BaTiO3-Based Multilayer Ceramic Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, Donhang

    2014-01-01

    The evaluation of multilayer ceramic capacitors (MLCCs) with Ni electrode and BaTiO3 dielectric material for potential space project applications requires an in-depth understanding of their reliability. A general reliability model for Ni-BaTiO3 MLCC is developed and discussed. The model consists of three parts: a statistical distribution; an acceleration function that describes how a capacitor's reliability life responds to the external stresses, and an empirical function that defines contribution of the structural and constructional characteristics of a multilayer capacitor device, such as the number of dielectric layers N, dielectric thickness d, average grain size, and capacitor chip size A. Application examples are also discussed based on the proposed reliability model for Ni-BaTiO3 MLCCs.

  17. A General Reliability Model for Ni-BaTiO3-Based Multilayer Ceramic Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, Donhang

    2014-01-01

    The evaluation for potential space project applications of multilayer ceramic capacitors (MLCCs) with Ni electrode and BaTiO3 dielectric material requires an in-depth understanding of the MLCCs reliability. A general reliability model for Ni-BaTiO3 MLCCs is developed and discussed in this paper. The model consists of three parts: a statistical distribution; an acceleration function that describes how a capacitors reliability life responds to external stresses; and an empirical function that defines the contribution of the structural and constructional characteristics of a multilayer capacitor device, such as the number of dielectric layers N, dielectric thickness d, average grain size r, and capacitor chip size A. Application examples are also discussed based on the proposed reliability model for Ni-BaTiO3 MLCCs.

  18. Final Report: BaBar Detector and Experimental at SLAC, September 30, 1998 - September 29, 1999

    SciTech Connect

    Judd, Dennis J.

    2000-01-20

    The Prairie View A&M University High Energy Physics Group with its contingent of three undergraduates physics majors, joined the BaBar Collaboration at SLAC in September 1994. BaBar is the experiment and detector running in the PEP-II ring at SLAC as part of the Asymmetric B Factory project there to study CP violation and heavy flavor physics. The focus of our effort before this year was with the Muon/Neutral Hadron Detector/Instrumented Flux Return (IFD) subgroup within the BaBar collaboration, and particularly with the GEANT simulation of the IFR. With the GEANT3 simulation essentially frozen, and the GEANT4 full simulation of the IFR done, we have decided to redirect our efforts toward other areas.

  19. Irreversibility in Ba sub 0. 625 K sub 0. 375 BiO sub 3

    SciTech Connect

    Shi, D. ); Ling, X.S. ); Xu, M. ); Fang, M.M. ); Luo, S.; Budnick, J.I. ); Dabrowski, B.; Hinks, D.G.; Richards, D.R.; Zheng, Y. )

    1991-02-01

    An irreversibility line has been identified in bulk Ba{sub 0.625}K{sub 0.375}BiO{sub 3}, which follows the relation 1{minus}{ital T}/{ital T}{sub {ital c}}{similar to}{ital H}{sup 2/3}. According to the flux-creep model, the magnetic irreversibility is caused by thermally activated flux creep and is closely connected with the field-induced resistive broadening. However, previous resistivity measurements showed that the Ba{sub 0.625}K{sub 0.375}BiO{sub 3} system did not exhibit resistive transition broadening. Thus, an alternative explanation based on the Josephson-coupling model is suggested to interpret the irreversibility observed in Ba{sub 0.625}K{sub 0.375}BiO{sub 3}.

  20. Mechanochemical preparation of nanocrystalline BaFCl doped with samarium in the 2+ oxidation state.

    PubMed

    Wang, Xiang-lei; Liu, Zhi-qiang; Stevens-Kalceff, Marion A; Riesen, Hans

    2014-09-01

    We report a facile mechanochemical preparation method for nanocrystalline BaFCl doped with samarium in the 2+ oxidation state by ball milling BaCl2, BaF2, and SmI2 under a nitrogen atmosphere. The resulting phosphors were characterized by powder X-ray diffraction; electron microscopy, X-ray photoelectron spectroscopy; and photoluminescence, photoexcitation, cathodoluminescence, and diffuse reflectance spectroscopy. This is the first report of a direct preparation method of Sm(2+) doped alkaline earth fluorohalides at room temperature and points to a significant potential for the preparation of a wide range of related X-ray storage phosphors containing rare earth ions in divalent and trivalent cationic states by mechanochemical methods.

  1. Preparation of BaZrO3 nanoparticles using a solvothermal reaction

    NASA Astrophysics Data System (ADS)

    Nakashima, Kouichi; Goto, Takayuki; Iwatsuki, Shougo; Kera, Masatoshi; Fujii, Ichiro; Wada, Satoshi

    2011-10-01

    Barium zirconate (BaZrO3) nanoparticles were successfully prepared by a solvothermal reaction. These were synthesized by a solvothermal method at 230°C -240°C for 18 h using a mixture solution of ethanol and 2-metoxy-thanol as the reaction medium. The prepared particles were collected using a centrifugal separator. The X-ray diffraction (XRD) measurement confirmed the presence of perovskite BaZrO3 particles. The scanning electron microscopy (SEM) observations revealed that the particles were composed of highly dispersed nanoparticles. The results of our study indicate that the addition of water to the reaction medium is an important for the preparation of a perovskite structure and control of the size of the BaZrO3.

  2. EXPLAINING THE Sr AND Ba SCATTER IN EXTREMELY METAL-POOR STARS

    SciTech Connect

    Aoki, W.; Suda, T.; Boyd, R. N.; Kajino, T.; Famiano, M. A. E-mail: takuma.suda@nao.ac.jp E-mail: kajino@nao.ac.jp

    2013-03-20

    Compilations of abundances of strontium and barium in extremely metal-poor stars show that an apparent cutoff is observed for [Sr/Ba] at [Fe/H] < -3.6 and large fluctuations for [Fe/H] > -3.6 with a clear upper bound depending on metallicity. We study the factors that place upper limits on the logarithmic ratio [Sr/Ba]. A model is developed in which the collapses of type II supernovae are found to reproduce many of the features seen in the data. This model is consistent with galactic chemical evolution constraints of light-element enrichment in metal-poor stars. Effects of turbulence in an explosive site have also been simulated, and are found to be important in explaining the large scatter observed in the [Sr/Ba] data.

  3. Spectroscopic and theoretical studies of the low-lying states of BaO+

    NASA Astrophysics Data System (ADS)

    Bartlett, Joshua H.; VanGundy, Robert A.; Heaven, Michael C.

    2015-07-01

    The BaO+ cation is of interest from the perspectives of electronic structure and the potential for cooling to ultra-cold temperatures. Spectroscopic data for the ion have been obtained using a two-color photoionization technique. The ionization energy for BaO was found to be 6.8123(3) eV. The ground state of BaO+ was identified as X2Σ+, and both vibrational and rotational constants were determined. Vibrationally resolved spectra were recorded for A2Π, the first electronically excited state. These data yielded the term energy, vibrational frequency, and the spin-orbit interaction constant. Relativistic electronic structure calculations were carried out using multi-reference configuration interaction (MRCI), coupled cluster and density functional theory methods. Transition moments for the pure vibrational and A2Π-X2Σ+ transitions were predicted using the MRCI method.

  4. The Composition and Structure of Y-Ba-Cu-O Superconductors

    NASA Astrophysics Data System (ADS)

    Hua, Z. Y.; Jia, C. L.; Cheng, H. S.; Cai, Y. M.; Jiang, A. R.

    High Tc superconductors of Y-Ba-Cu-O system with (Y+Ba):Cu=1~2 have been investigated. Results show that any sample in this system with a proportion of Y:Cu between 0.6 and 1.2 is oxygen-deficient and will be superconductive after sintering in an oxygen flow. In this system all superconductors with different nominal composition have a superconductive phase of perovskite-1ike YBa2Cu3O7 (Phase A), and the difference of constituents is shown in another phase (Phase B) which acts as a gettering center. When the composition has an excess of Y, there will be a third phase (Phase C) which has been identified as small particles of Y2O3. For an exact nominal proportion of Y:Ba:Cu=1:2:3, single-phase superconductors can be prepared.

  5. Pseudogap and anharmonic phonon behavior in Ba8Ga16Ge30: An NMR study.

    PubMed

    Sirusi, Ali A; Ross, Joseph H

    2016-08-01

    We have performed (69)Ga, (71)Ga, and (137)Ba NMR on Ba8Ga16Ge30, a clathrate semiconductor which has been of considerable interest due to its large figure of merit for thermoelectric applications. In measurements from 4 K to 450 K, we used measurements on the two Ga nuclei to separate the magnetic and electric quadrupole hyperfine contributions and thereby gain information about the metallic and phonon behavior. The results show the presence of a pseudogap in the Ga electronic states within the conduction band, superposed upon a large Ba contribution to the conduction band. Meanwhile the phonon contributions to the Ga relaxation rates are large and increase more rapidly with temperature than typical semiconductors. These results provide evidence for enhanced anharmonicity of the propagative phonon modes over a wide range, providing experimental evidence for enhanced phonon-phonon scattering as a mechanism for the reduced thermal conductivity. PMID:27497567

  6. Properties of epitaxial BaTiO{sub 3} deposited on GaAs

    SciTech Connect

    Contreras-Guerrero, R.; Droopad, R.; Veazey, J. P.; Levy, J.

    2013-01-07

    Single crystal BaTiO{sub 3} (BTO) has been grown epitaxially on GaAs using molecular beam epitaxy with a 2 unit cell SrTiO{sub 3} nucleation layer. The oxide film is lattice-matched to GaAs through an in-plane rotation of 45 Degree-Sign relative to the (100) surface leading to c-axis orientation of the BaTiO{sub 3}. X-ray diffraction confirmed the crystallinity and orientation of the oxide film with a full width half maximum of 0.58 Degree-Sign for a 7.5 nm thick layer. Piezoresponse force microscopy was used to characterize the ferroelectric domains in the BaTiO{sub 3} layer, and a coercive voltage of 1-2 V and piezoresponse amplitude {approx}5 pm/V was measured.

  7. Photomultiplier Tubes for BaF/sub 2//BGO crystal scintillators

    SciTech Connect

    Kume, H.; Watanabe, T.; Iida, M.; Matsushita, T.; Suzuki, S.

    1986-02-01

    BGO/BaF/sub 2/ crystals have been widely employed as scintillation detectors for radioactive sources and charged particles. Photomultiplier Tubes (PMT) are conventionally used on the detector with these scintillators. For these applications, the PMT with rectangular and dual photocathode (to be coupled with BGO crystal) was developed in order to reduce the dead space among PMTs in assembling them together as a ring camera. Furthermore, a PMT of 3/8'' in diameter with a fused silica window was developed for BaF/sub 2/ scintillator, so that it has the high spatial resolution as well as an excellent time resolving capability. This PMT exhibits the coincidence resolving time of 390 psec with positron emitter of Na-22 and BaF/sub 2/ crystals. In this paper, the authors report the basic design, construction and characteristics of these latest developed PMTs.

  8. Limited Streamer Tubes for the BaBar Instrumented Flux Return Upgrade

    SciTech Connect

    Lu, C.; /Princeton U.

    2005-10-11

    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&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&D results, and leave other issues of the IFR system upgrade to the future publications.

  9. AMiBA: Cluster Sunyaev-Zel’dovich Effect Observations with the Expanded 13-element Array

    NASA Astrophysics Data System (ADS)

    Lin, Kai-Yang; Nishioka, Hiroaki; Wang, Fu-Cheng; Locutus Huang, Chih-Wei; Liao, Yu-Wei; Proty Wu, Jiun-Huei; Koch, Patrick M.; Umetsu, Keiichi; Chen, Ming-Tang; Chan, Shun-Hsiang; Chang, Shu-Hao; Lucky Chang, Wen-Hsuan; Cheng, Tai-An; Duy, Hoang Ngoc; Fu, Szu-Yuan; Han, Chih-Chiang; Ho, Solomon; Ho, Ming-Feng; Ho, Paul T. P.; Huang, Yau-De; Jiang, Homin; Kubo, Derek Y.; Li, Chao-Te; Lin, Yu-Chiung; Liu, Guo-Chin; Martin-Cocher, Pierre; Molnar, Sandor M.; Nunez, Emmanuel; Oshiro, Peter; Pai, Shang-Ping; Raffin, Philippe; Ridenour, Anthony; Shih, Chia-You; Stoebner, Sara; Teo, Giap-Siong; Yeh, Jia-Long Johnny; Williams, Joshua; Birkinshaw, Mark

    2016-10-01

    The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) is a co-planar interferometer array operating at a wavelength of 3 mm to measure the Sunyaev–Zel’dovich effect (SZE) of galaxy clusters at arcminute scales. The first phase of operation—with a compact 7-element array with 0.6 m antennas (AMiBA-7)—observed six clusters at angular scales from 5\\prime to 23\\prime . Here, we describe the expansion of AMiBA to a 13-element array with 1.2 m antennas (AMiBA-13), its subsequent commissioning, and cluster SZE observing program. The most noticeable changes compared to AMiBA-7 are (1) array re-configuration with baselines ranging from 1.4 m to 4.8 m, allowing us to sample structures between 2\\prime and 10\\prime , (2) 13 new lightweight carbon-fiber-reinforced plastic (CFRP) 1.2 m reflectors, and (3) additional correlators and six new receivers. Since the reflectors are co-mounted on and distributed over the entire six-meter CFRP platform, a refined hexapod pointing error model and phase error correction scheme have been developed for AMiBA-13. These effects—entirely negligible for the earlier central close-packed AMiBA-7 configuration—can lead to additional geometrical delays during observations. Our correction scheme recovers at least 80 ± 5% of the point-source fluxes. We, therefore, apply an upward correcting factor of 1.25 to our visibilities to correct for phase decoherence, and a ±5% systematic uncertainty is added in quadrature with our statistical errors. We demonstrate the absence of further systematics with a noise level consistent with zero in stacked uv-visibilities. From the AMiBA-13 SZE observing program, we present here maps of a subset of 12 clusters with signal-to-noise ratios above five. We demonstrate combining AMiBA-7 with AMiBA-13 observations on Abell 1689, by jointly fitting their data to a generalized Navarro–Frenk–White model. Our cylindrically integrated Compton-y values for five radii are consistent with

  10. Field-effect BaTiO{sub 3}-Si solar cells

    SciTech Connect

    Wang, Wentao; Liu, Fude Man Lau, Chor; Wang, Lei; Yang, Guandong; Zheng, Dawei; Li, Zhigang

    2014-03-24

    Conventional solar cells make use of the spatial variation in electronic environment due to junctions for charge separation. We investigated field-effect BaTiO{sub 3}-Si solar cells that utilize the bound surface charges of BaTiO{sub 3} to separate charge carriers in silicon. Rectifying behavior and photovoltaic effect were observed on cells with forward polarization. Theoretical simulation indicated that the induced electric field due to BaTiO{sub 3} polarization could extend into the silicon layer, which is consistent with experimental observations. In addition, adjusting relevant parameters may optimize the electric field distribution. The cells are promising in terms of material selection, device design, and fabrication.

  11. Low Temperature Structural Phase Transition of Ba3NaIr2O9

    SciTech Connect

    Conrad, H.; Loye, Z; Kim, S; Macquart, R; Smith, M; Lee, Y; Vogt, T

    2009-01-01

    Single crystal X-ray and synchrotron X-ray powder diffraction have been used to probe the structure of Ba3NaIr2O9 from 300 K down to 20 K. Ba3NaIr2O9 is found to undergo a structural transition from hexagonal symmetry, P63/mmc, at ambient temperature to monoclinic symmetry, C2/c, at low temperature. The evolution of the unit cell volume upon cooling is indicative of a higher order structural transition, and the symmetry breaking becomes apparent as the temperature is decreased. The low temperature monoclinic structure of Ba3NaIr2O9 contains strongly distorted [NaO6] and [IrO6] octahedra in comparison to the room temperature hexagonal structure.

  12. Pulsed laser deposition of Tl-Ca-Ba-Cu-O films

    NASA Technical Reports Server (NTRS)

    Ianno, N. J.; Liou, S. H.; Woollam, John 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.

  13. Kinetics of Sr/Ba and Sr/Ca ion exchange in synthetic zeolite A

    SciTech Connect

    Gaus, H.; Lutze, W.

    1981-01-08

    The isotopic exchange kinetics of Sr, Ba, and Ca have been measured in zeolites with different compositions and found to be describable as self-diffusion. The self-diffusion coefficients are strongly dependent on the composition. Also the Sr/Ba and Sr/Ca ion exchanges are measured in both directions and described as interdiffusion. While for Sr/Ba tolerable agreement is reached, for Sr/Ca a modification is necessary. The interdiffusion coefficient is multiplied by a factor which takes into account the activity, i.e., the selectivity of the zeolite. As a continuation of an earlier paper the zeolite is described as a mixture of microcells and free water. The above-mentioned factor must be calculated for a nonequilibrium state with respect to the water content in order to get agreement with the measurements.

  14. Ba2TeO: A new layered oxytelluride

    SciTech Connect

    Besara, T.; Ramirez, D.; Sun, J.; Whalen, J. B.; Tokumoto, T. D.; McGill, S. A.; Singh, D. J.; Siegrist, T.

    2015-02-01

    For single crystals of the new semiconducting oxytelluride phase, Ba2TeO, we synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba2TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. Moreover, the optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba2TeO is highly insulating.

  15. Simulation of Cosmic Microwave Background Polarization Fields for AMiBA Experiment

    NASA Astrophysics Data System (ADS)

    Park, Chan-Gyung; Park, Changbom

    2002-06-01

    We have made a topological study of cosmic microwave background (CMB) polarization maps by simulating the AMiBA experiment results. A ΛCDM CMB sky is adopted to make mock interferometric observations designed for the AMiBA experiment. CMB polarization fields are reconstructed from the AMiBA mock visibility data using the maximum entropy method. We have also considered effects of Galactic foregrounds on the CMB polarization fields. The genus statistic is calculated from the simulated Q and U polarization maps, where Q and U are Stokes parameters. Our study shows that the Galactic foreground emission, even at low Galactic latitude, is expected to have small effects on the CMB polarization field. Increasing survey area and integration time is essential to detect non-Gaussian signals of cosmological origin through genus measurement.

  16. Transport and structural properties of the Ho1Ba2Cu3O9 - delta superconductor

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Ik; Golben, John P.; Song, Yi; Lee, Sang Young; Noh, Tae W.; Chen, Xiao-dong; Testa, Joe; Gaines, J. R.; Tettenhorst, Rodney T.

    1987-07-01

    The compound Ho1Ba2Cu3O9-δ has been found to be a high Tc superconductor. The onset of the superconducting transition is 88 K with zero resistance achieved at 87 K. The x-ray diffraction spectrum of this material shows it to be a single-phase perovskite similar to the Y1Ba2Cu3O9-δ compound but different from the K2NiF4 perovskite which is believed to be the superconducting phase for the La2(1-x) Ba2xCuO4-δ system. Possible oxygen deficiencies in several of the unit cell planes are discussed. The room-temperature resistance, the superconducting onset temperature, and the emergence of the single phase all depend upon the sample preparation firing conditions.

  17. Direct growth of nanocrystalline graphitic carbon films on BaF2 by alcohol CVD

    NASA Astrophysics Data System (ADS)

    Tan, Yan; Nakamura, Atsushi; Kubono, Atsushi

    2016-03-01

    Multilayered nanocrystalline graphitic carbon films were directly formed on BaF2 substrates by the alcohol chemical vapor deposition method using ethanol. Domain size was typically 46 nm as estimated from the peak intensity ratios of G- and D-band of the Raman spectra, which were higher than currently reported values for various dielectric substrates. Sheet resistance measured by the four-probe method was 900 Ω/sq. A possible formation mechanism of the graphitic carbon layer was discussed referring to the results of X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) for a composition analysis. It was found that the graphitic carbon layers were formed on the BaO surface, which was produced by the oxidization of the BaF2 substrate by the ethanol source.

  18. High-mobility BaSnO{sub 3} grown by oxide molecular beam epitaxy

    SciTech Connect

    Raghavan, Santosh; Schumann, Timo; Kim, Honggyu; Zhang, Jack Y.; Cain, Tyler A.; Stemmer, Susanne

    2016-01-01

    High-mobility perovskite BaSnO{sub 3} films are of significant interest as new wide bandgap semiconductors for power electronics, transparent conductors, and as high mobility channels for epitaxial integration with functional perovskites. Despite promising results for single crystals, high-mobility BaSnO{sub 3} films have been challenging to grow. Here, we demonstrate a modified oxide molecular beam epitaxy (MBE) approach, which supplies pre-oxidized SnO{sub x}. This technique addresses issues in the MBE of ternary stannates related to volatile SnO formation and enables growth of epitaxial, stoichiometric BaSnO{sub 3}. We demonstrate room temperature electron mobilities of 150 cm{sup 2} V{sup −1} s{sup −1} in films grown on PrScO{sub 3}. The results open up a wide range of opportunities for future electronic devices.

  19. Preparation and thermal behavior of aerosol-derived BaFe 12O 19 nanoparticles

    NASA Astrophysics Data System (ADS)

    Yu, Hsuan-Fu; Lin, Hsin-Yi

    2004-12-01

    Pure BaFe12O19 nanoparticles, having single magnetic domain sizes, were obtained at 700 °C using a process combining the citrate precursor method and spray technique. A neutralized aqueous solution, containing Ba2+ and Fe3+ chelated by citric acid, was nebulized to undergo thermal decomposition in a flowing air with a maximum temperature of 250 °C. The dried solid precursor so obtained was calcined at different temperatures and was then chemically and physically characterized. Crystalline barium hexaferrites were formed at temperatures as low as 650 °C, but calcination temperatures higher than 680 °C were required to produce pure barium ferrite powder. Based on the obtained experimental results, the reaction mechanism for the aerosol-derived precursor to form BaFe12O19 was proposed and discussed in this study.

  20. Redetermination of Ba(2)CdTe(3) from single-crystal X-ray data.

    PubMed

    Yang, Min; Xia, Sheng-Qing; Tao, Xu-Tang

    2012-10-01

    The previous structure determination of the title compound, dibarium tritelluridocadmate, was based on powder X-ray diffraction data [Wang & DiSalvo (1999 ▶). J. Solid State Chem.148, 464-467]. In the current redetermination from single-crystal X-ray data, all atoms were refined with anisotropic displacement parameters. The previous structure report is generally confirmed, but with some differences in bond lengths. Ba(2)CdTe(3) is isotypic with Ba(2)MX(3) (M = Mn, Cd; X = S, Se) and features (1) (∞)[CdTe(2/2)Te(2/1)](4-) chains of corner-sharing CdTe(4) tetra-hedra running parallel [010]. The two Ba(2+) cations are located between the chains, both within distorted monocapped trigonal-prismatic coordination polyhedra. All atoms in the structure are located on a mirror plane.

  1. Superconductivity in the Tl-Ca-Ba-Cu-O System:. Synthesis, Characterization and Mechanism

    NASA Astrophysics Data System (ADS)

    Ganguli, A. K.; Swamy, K. S. Nanjunda; Subbanna, G. N.; Rajumon, M. K.; Sarma, D. D.; Rao, C. N. R.

    Synthesis and characterization of some of the members of the Tl-Ca-Ba-Cu-O system are presented. Tc in both the TlCan-1Ba2CunO2n+3 and Tl2Can-1Ba2CunO2n+4 series increase with the number of Cu-O layers, n; Tc in the latter series with two Tl-O layers are generally higher than in the former with a single Tl-O layer. Tl in the cuprates is in the 3+ state while Cu is in the 1+ and 2+ states, showing the importance of oxygen holes. The concentration of these holes seems to increase with the number of Tl-O layers.

  2. Experimental and first principle studies on electronic structure of BaTiO{sub 3}

    SciTech Connect

    Sagdeo, Archna Ghosh, Haranath Chakrabarti, Aparna Kamal, C. Ganguli, Tapas Deb, S. K.; Phase, D. M.

    2014-04-24

    We have carried out photoemission experiments to obtain valence band spectra of various crystallographic symmetries of BaTiO{sub 3} system which arise as a function of temperature. We also present results of a detailed first principle study of these symmetries of BaTiO{sub 3} using generalized gradient approximation for the exchange-correlation potential. Here we present theoretical results of density of states obtained from DFT based simulations to compare with the experimental valence band spectra. Further, we also perform calculations using post density functional approaches like GGA + U method as well as non-local hybrid exchange-correlation potentials like PBE0, B3LYP, HSE in order to understand the extent of effect of correlation on band gaps of different available crystallographic symmetries (5 in number) of BaTiO{sub 3}.

  3. Growth and characterization of Ba3InB9O18 single crystals

    NASA Astrophysics Data System (ADS)

    Lv, Xian-Shun; Li, Qing-Gang; Liu, Bing; Zhang, Yuan-Yuan; Wei, Lei; Yang, Yu-Guo; Wang, Xu-Ping; Xu, Jian-Hua; Ma, Ling; Wang, Ji-Yang

    2016-09-01

    Ba3InB9O18 is expected to be potential ultraviolet optical materials. In this work, a crack free and colorless transparent Ba3InB9O18 single crystal has been grown by the Czochralski technique. The as-grown Ba3InB9O18 crystals show good UV transparency with the cutoff wavelength locating at 195 nm. An indirect band gap of 5.25 eV was obtained from the calculated electronic structure results. The factor group analysis results show that the total lattice modes are 15Au + 14Bg + 36E1u + 28E2u + 34E2g + 26E1g + 17Bu + 16Ag, of which 17E2g + 13E1g + 16Ag are Raman-active. The strongest recorded Raman peak at 642 cm-1 was assigned with the assistance of the first-principle calculation and factor group analysis results.

  4. Electric Properties of [(BaO)1.00(XO)x](Ti0.95Zr0.05)O2 (X = Ca, Sr, Ba) Ceramics Fired under Reduced Atmosphere

    NASA Astrophysics Data System (ADS)

    Sakai, Yuichi; Futakuchi, Tomoaki; Adachi, Masatoshi

    2009-09-01

    Ba(Ti0.95Zr0.05)O3 doped with CaO, SrO, or BaO was investigated in order to develop materials suitable for lead-free actuators with resistance to reduction. The grain sizes of [(BaO)1.00(XO)x](Ti0.95Zr0.05)O2 (X = Ca, Sr, Ba; x = 0-0.05) ceramics decreased with increasing amount of dopant concentration x. The grain sizes of the ceramics with a dopant concentration x in the range of 0.005 to 0.05 are approximately 1-2 µm. The crystalline phases of the ceramics with a dopant concentration x = 0.01 or less were perovskite single phases. CaO, SrO, or BaO doping concentrations of x = 0.005 or more were effective for preventing the reduction of Ba(Ti0.95Zr0.05)O3 during firing under 3% H2-N2 atmosphere. The remanent polarizations and dynamic piezoelectric constants of the ceramics decreased with increasing dopant concentration of CaO, SrO, or BaO. The dynamic piezoelectric constant of the ceramics with BaO dopant concentration x of 0.005 was approximately 640 pm/V. The Curie temperature was approximately 109 °C in this composition.

  5. Photoluminescence and Raman scattering spectroscopies of BaSiF6:Mn4+ red phosphor

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Daisuke; Nara, Jun-ichi; Adachi, Sadao

    2013-05-01

    We report on a simple method of synthesizing BaSiF6:Mn4+ red phosphor by chemical reaction of BaCl2.2H2O in a H2SiF6 solution. The Mn4+-activated BaSiF6 phosphor exhibits sharp red emission peaks at ˜630 nm. The optical properties of BaSiF6:Mn4+ are investigated using photoluminescence (PL) analysis, PL excitation spectroscopy, luminescence decay time measurement, and Raman scattering spectroscopy. The zero-phonon line (ZPL) emission and excitation peaks in BaSiF6:Mn4+ are observed to occur at ˜1.99 eV (2E → 4A2), ˜2.43 eV (4A2 → 4T2), and ˜2.86 eV (4A2 → 4T1) at 300 K. The ZPL and phonon-assisted emission peaks show clear splittings with energy of ˜3 meV being due to the trigonal distortion of the MnF62- octahedron in the BaSiF6 host. A single exponential decay time of ˜6.5 ms is observed, which is indicative of the forbidden character of the intra-d-shell transitions in Mn4+ ions. Temperature dependence of the PL intensity is also measured between T = 20 and 300 K with steps of 10 K and interpreted by taking into consideration the Bose-Einstein phonon statistics together with the thermal quenching process.

  6. Diamagnetic vortex barrier stripes in underdoped BaFe2(As1-xPx) 2

    NASA Astrophysics Data System (ADS)

    Yagil, A.; Lamhot, Y.; Almoalem, A.; Kasahara, S.; Watashige, T.; Shibauchi, T.; Matsuda, Y.; Auslaender, O. M.

    2016-08-01

    We report magnetic force microscopy (MFM) measurements on underdoped BaFe2(As1 -xPx)2 (x =0.26 ) that show enhanced superconductivity along stripes parallel to twin boundaries. These stripes of enhanced diamagnetic response repel superconducting vortices and act as barriers for them to cross. The width of the stripes is hundreds of nanometers, on the scale of the penetration depth, well within the inherent spatial resolution of MFM and implying that the width is set by the interaction of the superconductor with the MFM's magnetic tip. Unlike similar stripes observed previously by scanning SQUID in the electron doped Ba (Fe1 -xCox)2As2 , the stripes in the isovalently doped BaFe2(As1 -xPx)2 disappear gradually when we warm the sample towards the superconducting transition temperature. Moreover, we find that the stripes move well below the reported structural transition temperature in BaFe2(As1 -xPx)2 and that they can be much denser than in the Ba (Fe1 -xCox)2As2 study. When we cool in finite magnetic field we find that some vortices appear in the middle of stripes, suggesting that the stripes may have an inner structure, which we cannot resolve. Finally, we use both vortex decoration at higher magnetic field and deliberate vortex dragging by the MFM magnetic tip to obtain bounds on the strength of the interaction between the stripes and vortices. We find that this interaction is strong enough to play a significant role in determining the critical current in underdoped BaFe2(As1 -xPx)2 .

  7. Frustration of Negative Capacitance in Al2O3/BaTiO3 Bilayer Structure

    PubMed Central

    Kim, Yu Jin; Park, Min Hyuk; Lee, Young Hwan; Kim, Han Joon; Jeon, Woojin; Moon, Taehwan; Do Kim, Keum; Jeong, Doo Seok; Yamada, Hiroyuki; Hwang, Cheol Seong

    2016-01-01

    Enhancement of capacitance by negative capacitance (NC) effect in a dielectric/ferroelectric (DE/FE) stacked film is gaining a greater interest. While the previous theory on NC effect was based on the Landau-Ginzburg-Devonshire theory, this work adopted a modified formalism to incorporate the depolarization effect to describe the energy of the general DE/FE system. The model predicted that the SrTiO3/BaTiO3 system will show a capacitance boost effect. It was also predicted that the 5 nm-thick Al2O3/150 nm-thick BaTiO3 system shows the capacitance boost effect with no FE-like hysteresis behavior, which was inconsistent with the experimental results; the amorphous-Al2O3/epitaxial-BaTiO3 system showed a typical FE-like hysteresis loop in the polarization – voltage test. This was due to the involvement of the trapped charges at the DE/FE interface, originating from the very high field across the thin Al2O3 layer when the BaTiO3 layer played a role as the NC layer. Therefore, the NC effect in the Al2O3/BaTiO3 system was frustrated by the involvement of reversible interface charge; the highly stored charge by the NC effect of the BaTiO3 during the charging period could not be retrieved during the discharging process because integral part of the polarization charge was retained within the system as a remanent polarization. PMID:26742878

  8. A new barium titanium (III) pyrophosphate: BaTi 2(P 2O 7) 2

    NASA Astrophysics Data System (ADS)

    Wang, Shumin; Hwu, Shiou-Jyh

    1991-01-01

    The new barium titanium (III) pyrophosphate BaTi 2(P 2O 7) 2 has been prepared by conventional high temperature solid state reaction at 900°C in a fused silica tube. BaTi 2(P 2O 7) 2 crystallizes with four formula units in a cell with dimensions a = 10.680(3) Å, b = 10.564(4) Å, c = 9.834(4) Å/, β = 102.88(3)° and V = 1081.6(6) Å 3 in space group C 62h  C {2}/{c} (No. 15) of the monoclinic system. The single crystal structure refinement gives a final structure solution with R index on F2o of 0.018 for 99 variables and GOF = 1.05. BaTi 2(P 2O 7) 2 displays a new layered type structure which consists of layers of slightly distorted TiO 6 octahedra with (P 2O 7) and (BaO 10) polyhedra between the layers. The structural framework is built up from corner-sharing TiO 6 octahedra and P 2O 7 pyrophosphate groups, to give rise to [Ti 2(P 2O 7) 2] 2- units and to form tunnels where the barium cations reside. Magnetic susceptibility measurements on selected single crystals confirm the presence of Ti 3+ ( d1) ions with spin S = {1}/{2}. The high oxidative thermal stability of BaTi 2(P 2O 7) 2 versus the stabilities of other trivalent titanium cation-containing compounds, including Ti 2O 3, TiPO 4, and BaTi 2(PO 4) 3, owing to possible anion matrix effects are discussed.

  9. Crystal structure and polarization hysteresis properties of ferroelectric BaTiO3 thin-film capacitors on (Ba,Sr)TiO3-buffered substrates

    NASA Astrophysics Data System (ADS)

    Maki, Hisashi; Noguchi, Yuji; Kutsuna, Kazutoshi; Matsuo, Hiroki; Kitanaka, Yuuki; Miyayama, Masaru

    2016-10-01

    Ferroelectric BaTiO3 (BT) thin-film capacitors with a buffer layer of (Ba1- x Sr x )TiO3 (BST) have been fabricated on (001) SrTiO3 (STO) single-crystal substrates by a pulsed laser deposition method, and the crystal structure and polarization hysteresis properties have been investigated. X-ray diffraction reciprocal space mapping shows that the BST buffer effectively reduces the misfit strain relaxation of the BT films on SrRuO3 (SRO) electrodes. The BT capacitor with the SRO electrodes on the BST (x = 0.3) buffer exhibits a well-saturated hysteresis loop with a remanent polarization of 29 µC/cm2. The hysteresis loop displays a shift toward a specific field direction, which is suggested to stem from the flexoelectric coupling between the out-of-plane polarization and the strain gradient adjacent to the bottom interface.

  10. Conductor-backed coplanar waveguide resonators of Y-Ba-Cu-O and Tl-Ba-Ca-Cu-O on LaAlO3

    NASA Technical Reports Server (NTRS)

    Miranda, F. A.; Bhasin, K. B.; Stan, M. A.; Kong, K. S.; Itoh, T.

    1992-01-01

    Conductor-backed coplanar waveguide (CBCPW) resonators operating at 10.8 GHz have been fabricated from Tl-Ba-Ca-O (TBCCO) and Y-Ba-Cu-O (YBCO) thin films on LaAlO3. The resonators consist of a coplanar waveguide (CPW) patterned on the superconducting film side of the LaAlO3 substrate with a gold ground plane coated on the opposite side. These resonators were tested in the temperature range from 14 to 106 K. At 77 K, the best of our TBCCO and YBCO resonators have an unloaded quality factor (Qo) 7 and 4 times, respectively, larger than that of a similar all-gold resonator. In this study, the Qo's of the TBCCO resonators were larger than those of their YBCO counterparts throughout the aforementioned temperature range.

  11. The luminescence of BaF{sub 2} nanoparticles upon high-energy excitation

    SciTech Connect

    Vistovskyy, V. V. Zhyshkovych, A. V.; Halyatkin, O. O.; Voloshinovskii, A. S.; Mitina, N. E.; Zaichenko, A. S.; Rodnyi, P. A.; Vasil'ev, A. N.; Gektin, A. V.

    2014-08-07

    The dependence of X-ray excited luminescence intensity on BaF{sub 2} nanoparticle size was studied. A sharp decrease of self-trapped exciton luminescence intensity was observed when the nanoparticle size is less than 80 nm. The main mechanism of the luminescence quenching is caused by the escape of electrons from the nanoparticles. Escape of electrons from nanoparticles is confirmed by the considerable increase of luminescence intensity of the polystyrene scintillator with embedded BaF{sub 2} nanoparticles comparing with pure polystyrene scintillator.

  12. Thermophysical properties of proton conducting perovskite: BaCeO{sub 3}

    SciTech Connect

    Shukla, Aarti Parey, Vanshree; Thakur, Rasna; Shrivastava, Archana; Gaur, N. K.

    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)

  13. Synthesis and characterization of hollow mesoporous BaFe12O19 spheres

    SciTech Connect

    Xu, X; Park, J; Hong, YK; Lane, AM

    2015-02-01

    A facile method is reported to synthesize hollow mesoporous BaFe12O19 spheres using a template-free chemical etching process. Hollow BaFe12O19 spheres were synthesized by conventional spray pyrolysis. The mesoporous structure is achieved by alkaline ethylene glycol etching at 185 degrees C, with the porosity controlled by the heating time. The hollow porous structure is confirmed by SEM, TEM, and FIB-FESEM characterization. The crystal structure and magnetic properties are not significantly affected after the chemical etching process. The formation mechanism of the porous structure is explained by grain boundary etching. (C) 2014 Elsevier Inc. All rights reserved.

  14. Non Fermi Liquid behavior and disorder in BaVS3

    NASA Astrophysics Data System (ADS)

    Akrap, Ana; Barisic, Neven; Rullier-Albenque, Florence; Berger, Helmuth; Forro, Laszlo

    2009-03-01

    In strongly correlated BaVS3, the interplay between a wide one-dimensional dz^2 band and the localized eg electrons leads to a wealth of electronic phases. In this work we investigate the high pressure non-Fermi liquid (NFL) phase of BaVS3 by means of transport measurements, focusing on the influence of disorder, introduced by fast electron irradiation and sulfur deficiency. Our results are interpreted within a novel scenario in which quasi-one dimensional 2kF-CDW fluctuations are responsible for the NFL behavior.ootnotetextN. Barisi'c et al., arXiv:0712.3393v1

  15. Spin-driven multiferroics in BaYFeO{sub 4}

    SciTech Connect

    Cong, Jun-Zhuang; Shen, Shi-Peng; Chai, Yi-Sheng; Yan, Li-Qin; Shang, Da-Shan; Wang, Shou-Guo; Sun, Young

    2015-05-07

    We report on the spin-driven multiferroic property and magnetoelectric effect in the lately synthesized compound BaYFeO{sub 4}. Due to its peculiar crystal structure, the system exhibits complex magnetic phases with multiple transitions. The dielectric and pyroelectric measurements evidence a spin-driven multiferroic state raised by the cycloidal spin structure below T{sub 1} = 36 K. Strong magnetoelectric effect has also been observed in the multiferroic state. The origin of noncollinear cycloidal spin structure in BaYFeO{sub 4} is believed to arise from the interactions between low-dimensional magnetic columns.

  16. Crystal structures and phase transitions in Ba{sub 2}HoTaO{sub 6}

    SciTech Connect

    Kennedy, Brendan J. Saines, Paul J.; Kubota, Yoshiki; Minakata, Chiharu; Hano, Hiroko; Kato, Kenichi; Takata, Masaki

    2007-11-06

    The structure of the cation-ordered double perovskite Ba{sub 2}HoTaO{sub 6} was examined using synchrotron X-ray powder diffraction at fine temperature intervals over the range of 90-300 K. Ba{sub 2}HoTaO{sub 6} has a cubic structure in space group Fm3-barm at room temperature. A proper ferroelastic phase transition to I4/m tetragonal symmetry occurs near approximately 260 K. Analysis of the spontaneous tetragonal strain versus temperature indicated that the phase transition is second order in nature.

  17. Processing, electrical and microwave properties of sputtered Tl-Ca-Ba-Cu-O superconducting thin films

    NASA Technical Reports Server (NTRS)

    Subramanyam, G.; Kapoor, V. J.; Chorey, C. M.; Bhasin, K. B.

    1993-01-01

    A reproducible fabrication process has been established for TlCaBaCuO thin films on LaAlO3 substrates by RF magnetron sputtering and post-deposition processing methods. Electrical transport properties of the thin films were measured on patterned four-probe test devices. Microwave properties of the films were obtained from unloaded Q measurements of all-superconducting ring resonators. This paper describes the processing, electrical and microwave properties of Tl2Ca1Ba2Cu2O(x) 2122-plane phase thin films.

  18. Energy Calibration of the BaBar EMC Using the Pi0 Invariant Mass Method

    SciTech Connect

    Tanner, David J.; /Manchester U.

    2007-04-06

    The BaBar electromagnetic calorimeter energy calibration method was compared with the local and global peak iteration procedures, of Crystal Barrel and CLEO-II. An investigation was made of the possibility of {Upsilon}(4S) background reduction which could lead to increased statistics over a shorter time interval, for efficient calibration runs. The BaBar software package was used with unreconstructed data to study the energy response of the calorimeter, by utilizing the {pi}{sup 0} mass constraint on pairs of photon clusters.

  19. Structural properties of composites of polyvinylidene fluoride and mechanically activated BaTiO3 particles

    NASA Astrophysics Data System (ADS)

    Pavlović, V. P.; Pavlović, V. B.; Vlahović, B.; Božanić, D. K.; Pajović, J. D.; Dojčilović, R.; Djoković, V.

    2013-11-01

    Nanocomposites of electroactive ceramics and ferroelectric polymers exploit favorable features of the matrix polymer and the nanostructured filler to produce new functional materials for pressure and IR sensors. In this study, the influence of mechanical activation of barium titanate (BaTiO3) particles on the structural properties of BaTiO3/polyvinylidene fluoride (PVDF) nanocomposites was investigated. Nanocomposite films were prepared by the solution casting method and characterized by scanning electron microscopy, x-ray diffraction and Raman spectroscopy. It was found that mechanically activated fillers promote the formation of a ferroelectric β-phase during crystallization of PVDF.

  20. Combined backscatter Moessbauer spectrometer/x ray fluorescence analyzer (BaMS/XRF) for extraterrestrial surfaces

    NASA Technical Reports Server (NTRS)

    Shelfer, T. D.; Wills, E. L.; Agresti, D. G.; Pimperl, M. M.; Shen, M. H.; Morris, R. V.; Nguyen, T.

    1993-01-01

    We have designed and tested a prototype combined backscatter Moessbauer spectrometer and x-ray fluorescence analyzer (BaMS/XRF). A space qualified instrument based on this design would be suitable for in-situ use on planetary missions to the surfaces of the Moon (Artemis and lunar outpost), Mars (MESUR), asteroids, or other solid solar system objects. The BaMS/XRF instrument is designed to be capable of concurrent sample analyses for the mineralogy of iron-bearing phases and elemental composition without the need for sample preparation.

  1. Luminescent and kinetic properties of the polystyrene composites based on BaF2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Demkiv, T. M.; Halyatkin, O. O.; Vistovskyy, V. V.; Gektin, A. V.; Voloshinovskii, A. S.

    2016-02-01

    Luminescence-kinetic properties of polystyrene composites based on BaF2 nanoparticles were studied. The electron emission from the nanoparticles due to the photoelectric effect is the main luminescence excitation mechanism in the case of polystyrene composites loaded with small BaF2 nanoparticles (~20 nm). Scintillation pulse of polystyrene composites possesses only fast decay component with the time constant τ~2 ns, and its emission intensity considerably exceeds the one for pure polystyrene scintillator upon the X-ray excitations.

  2. Magnetoelectric coupling in ordered arrays of multilayered heteroepitaxial BaTiO₃/CoFe₂O₄ nanodots.

    PubMed

    Lu, Xiaoli; Kim, Yunseok; Goetze, Silvana; Li, Xiaoguang; Dong, Sining; Werner, Peter; Alexe, Marin; Hesse, Dietrich

    2011-08-10

    Fully epitaxial BaTiO(3)/CoFe(2)O(4) ferroelectric/ferromagnetic multilayered nanodot arrays, a new type of magnetoelectric (ME) nanocomposite with both horizontal and vertical orderings, were fabricated via a stencil-derived direct epitaxy technique. By reducing the clamping effect, ferroelectric domain modification and distinct magnetization change proportional to different interfacial area around the BaTiO(3) phase transition temperatures were found, which may pave the way to quantitative introducing of ME coupling at nanoscale and build high density multistate memory devices. PMID:21749120

  3. Pr Substitution at Y and Ba sites in YBCO (123) System

    NASA Astrophysics Data System (ADS)

    Sharma, P. K.; Kumar, Sudhish; Dolia, S. N.; Singhal, R. K.

    2011-07-01

    We present structural, transport, and iodometric study of YBa2Cu3O7-δ system with Pr3+ substituting both the Y3+ and the Ba2+sites. The rate of the Tc depression in the case when with Pr3+ substitutes the Ba2+ is much higher than the case when Pr3+ is substituted at the Y3+ site. This is explained due to a composite effect of the depletion of itinerant holes due to the progressive depletion of the oxygen content, and the loss of orthorhombicity. Further studies on electronic structure and itinerant holes and their relation with superconductivity are underway.

  4. Lowest four-quasiparticle magnetic dipole band in {sup 128}Ba

    SciTech Connect

    Vogel, O.; Dewald, A.; von Brentano, P.; Gableske, J.; Kruecken, R.; Nicolay, N.; Gelberg, A.; Petkov, P.; Gizon, A.; Gizon, J.; Bazzacco, D.; Rossi Alvarez, C.; Pavan, P.; Lunardi, S.; Napoli, D.R.; Frauendorf, S.; Doenau, F.

    1997-09-01

    The four-quasiparticle magnetic dipole band in {sup 128}Ba has been investigated with the {sup 96}Zr({sup 36}S,4n){sup 128}Ba reaction at the GASP spectrometer of the Laboratori Nazionali di Legnaro. Linking transitions to the previously known positive parity states have been observed for the first time in this mass region and new transitions on top of the band have been found. The experimental results are compared to previously made tilted axis cranking calculations. {copyright} {ital 1997} {ital The American Physical Society}

  5. Variations in the morphotropic phase boundary with Bi deficiency on Ba-substituted sodium bismuth titanate

    NASA Astrophysics Data System (ADS)

    Yamatoh, Tomonori; Fujimori, Hirotaka

    2016-08-01

    We successfully demonstrated that a slight Bi deficiency causes the rhombohedral-tetragonal morphotropic phase boundary (MPB) to shift to the considerably lower Ba content in a (Na0.5Bi0.5)1-xBaxTiO3 (Ba-substituted NBT) system. Rietveld analysis revealed that the composition yielding the MPB was located at x = 0.10 when using the polymerizable complex method to prevent evaporation of sodium and bismuth and at x = 0.068 in samples of (Na0.5Bi0.5-z)1-xBaxTiO3-δ with a Bi deficiency of z = 0.03.

  6. Stability limits of the perovskite structure in the Y-Ba-Cu-O system

    NASA Astrophysics Data System (ADS)

    Bormann, R.; Nölting, J.

    1989-05-01

    The equilibrium (molecular) oxygen partial pressure of the Y1Ba2Cu3O7-x phase has been measured by an electrochemical method. The investigations are focused on the low-temperature range between 560 and 750 °C and on oxygen stoichiometries close to the oxygen-poor phase boundary. In particular, the oxygen partial pressure has been determined below which the perovskite structure becomes thermodynamically unstable. This critical value should be considered during the preparation of high Tc Y1Ba2Cu3O7-x superconductors, especially in the case of an in situ preparation of thin films.

  7. Critical currents of aligned grains of Tl-Ba-Ca-Cu-O compounds

    NASA Technical Reports Server (NTRS)

    Fang, M. M.; Finnemore, D. K.; Farrell, D. E.; Bansal, N. R.

    1989-01-01

    A study of irreversibility in the magnetization curves of Tl2Ba2Ca2Cu3O10 and Tl2Ba2Ca1Cu2O8 was undertaken to determine the intragranular critical currents and the effects of flux-creep in grain-aligned samples of these materials. For fields of greater than 0.3 T, and H parallel to c axis, the critical supercurrent falls approximately exponentially with both magnetic field and temperature. Flux-creep is found to be linear in the logarithm of time at low fields over a wide temperature range.

  8. Electron-hole asymmetry, Dirac fermions, and quantum magnetoresistance in BaMnBi2

    NASA Astrophysics Data System (ADS)

    Li, Lijun; Wang, Kefeng; Graf, D.; Wang, Limin; Wang, Aifeng; Petrovic, C.

    2016-03-01

    We report two-dimensional quantum transport and Dirac fermions in BaMnBi2 single crystals. BaMnBi2 is a layered bad metal with highly anisotropic conductivity and magnetic order below 290 K. Magnetotransport properties, nonzero Berry phase, small cyclotron mass, and the first-principles band structure calculations indicate the presence of Dirac fermions in Bi square nets. Quantum oscillations in the Hall channel suggest the presence of both electron and hole pockets, whereas Dirac and parabolic states coexist at the Fermi level.

  9. Calculation of the specific heat of optimally K-doped BaFe₂As₂.

    PubMed

    Oh, Hyungju; Coh, Sinisa; Cohen, Marvin L

    2015-08-26

    The calculated specific heat of optimally K-doped BaFe2As2 in density functional theory is about five times smaller than that found in the experiment. We report that by adjusting the potential on the iron atom to be slightly more repulsive for electrons improves the calculated heat capacity as well as the electronic band structure of Ba0.6K0.4Fe2As2. In addition, structural and magnetic properties are moved in the direction of experimental values. Applying the same correction to the antiferromagnetic state, we find that the electron-phonon coupling is strongly enhanced.

  10. Crossings in alternating-parity bands of neutron-rich Ba nuclei

    SciTech Connect

    Urban, W.; Jones, M.A.; Durell, J.L.

    1995-07-22

    {sup 144}Ba and {sup 146}Ba nuclei produced in the spontaneous fission of {sup 248}Cm have been studied using the EUROGRAM II array. Spins and parities of excited levels have been deduced from triple-{gamma} angular correlation and direction-polarization correlation measurements, which is the first use of these techniques in studies of fission product nuclei. Ground-state, alternating-parity bands have been extended significantly and crossing in these bands has been found in both isotopes. For the first time alternating-parity band termination by particle alignment has been observed.

  11. Electron-hole asymmetry, Dirac fermions, and quantum magnetoresistance in BaMnBi2

    DOE PAGES

    Li, Lijun; Wang, Kefeng; Graf, D.; Wang, Limin; Wang, Aifeng; Petrovic, C.

    2016-03-28

    Here, we report two-dimensional quantum transport and Dirac fermions in BaMnBi2 single crystals. BaMnBi2 is a layered bad metal with highly anisotropic conductivity and magnetic order below 290 K. Magnetotransport properties, nonzero Berry phase, small cyclotron mass, and the first-principles band structure calculations indicate the presence of Dirac fermions in Bi square nets. Quantum oscillations in the Hall channel suggest the presence of both electron and hole pockets, whereas Dirac and parabolic states coexist at the Fermi level.

  12. The role of BaCO{sub 3} in high temperature synthesis of electronic materials

    SciTech Connect

    Malecki, A.; Oblakowski, J.; Labus, S.

    1995-06-01

    The syntheses of superconducting YBCO powders, prepared by solid state reaction, vacuum pyrolysis of acetates, spray pyrolysis of acetates and calcinated oxalates were performed. All of the powders in a paste form were deposited on the Al{sub 2}O{sub 3} substrate. After sintering and annealing the obtained superconducting YBCO thick layers were examined in different (CO{sub 2}+O{sub 2}) atmospheres. The thermogravimetric as well as IR spectroscopy and SEM study confirm that on the grain boundaries the BaCO{sub 3} phase is formed. The presence of BaCO{sub 3} phase may cause degradation of superconducting materials.

  13. Reflectance Profile of BaTiO3 on Multilayer Antireflection Coating Systems

    NASA Astrophysics Data System (ADS)

    Karaomerlioglu, Filiz

    2011-05-01

    Antireflection (AR) coating systems are very important technology for optoelectronic devices. The optical characteristics of the system can be regulated by external electric or thermal field, and designed broadband ultra low reflection coating systems. It is investigated optical properties of multilayer AR coatings based on different ferroelectric materials to reduce reflectance in other studies. In this study, reflectance profile of BaTiO3 on multilayer AR coating systems has been developed in the visible region. It has been used ZnSe and ZrO2 as multilayer AR coatings, and BaTiO3 as the substrate. Fortran program has been simulated on Fresnell equations base.

  14. Three-phase percolative silver-BaTiO3-epoxy nanocomposites with high dielectric constants

    SciTech Connect

    Qi, Lai; Lee, Burtrand I.; Samuels, William D.; Exarhos, Gregory J.; Parker, Sam G.

    2006-08-01

    A three-phase epoxy-based composite with randomly distributed Ag nanoparticles and BaTiO3 particles was synthesized in this work. By integrating Ag nanoparticles into the epoxy resin, the dielectric properties of the resin is significantly enhanced, which provides an ideal host for further mixing with BaTiO3 to prepare high-dielectric-constant polymer-based dielectrics. The devices that adopt these composites demonstrate high relative dielectric constants (?r ? 450) at room temperature, which is 110 times higher than that of the epoxy matrix. These nanocomposites were found with potential to be applied in the embedded capacitor applications.

  15. Crystal growth of Ba 3BP 3O 12 with BPO 4-NaF flux

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-Jun; Wang, Hong; Hu, Guan-Qin; Chen, Hao-Hong; Yang, Xin-Xin; Zhao, Jing-Tai

    2010-04-01

    Single crystals of Ba 3BP 3O 12 with size of 10×8×2 mm 3 have been grown by the top-seeded solution growth (TSSG) method using BPO 4-NaF mixture as the flux. The crystals were characterized by X-ray powder diffraction, field emission scanning electron microscopy (FE-SEM) and transmittance spectrum. Ba 3BP 3O 12 single crystal exhibits wide transparency in the range 250-800 nm. The preparation process of starting materials and the effect of flux on the crystal growth were discussed.

  16. A New Family of Perovskite Catalysts for Oxygen-Evolution Reaction in Alkaline Media: BaNiO3 and BaNi(0.83)O(2.5).

    PubMed

    Lee, Jin Goo; Hwang, Jeemin; Hwang, Ho Jung; Jeon, Ok Sung; Jang, Jeongseok; Kwon, Ohchan; Lee, Yeayeon; Han, Byungchan; Shul, Yong-Gun

    2016-03-16

    Establishment of a sustainable energy society has been strong driving force to develop cost-effective and highly active catalysts for energy conversion and storage devices such as metal-air batteries and electrochemical water splitting systems. This is because the oxygen evolution reaction (OER), a vital reaction for the operation, is substantially sluggish even with precious metals-based catalysts. Here, we show for the first time that a hexagonal perovskite, BaNiO3, can be a highly functional catalyst for OER in alkaline media. We demonstrate that the BaNiO3 performs OER activity at least an order of magnitude higher than an IrO2 catalyst. Using integrated density functional theory calculations and experimental validations, we unveil that the underlying mechanism originates from structural transformation from BaNiO3 to BaNi(0.83)O(2.5) (Ba6Ni5O15) over the OER cycling process.

  17. A New Family of Perovskite Catalysts for Oxygen-Evolution Reaction in Alkaline Media: BaNiO3 and BaNi(0.83)O(2.5).

    PubMed

    Lee, Jin Goo; Hwang, Jeemin; Hwang, Ho Jung; Jeon, Ok Sung; Jang, Jeongseok; Kwon, Ohchan; Lee, Yeayeon; Han, Byungchan; Shul, Yong-Gun

    2016-03-16

    Establishment of a sustainable energy society has been strong driving force to develop cost-effective and highly active catalysts for energy conversion and storage devices such as metal-air batteries and electrochemical water splitting systems. This is because the oxygen evolution reaction (OER), a vital reaction for the operation, is substantially sluggish even with precious metals-based catalysts. Here, we show for the first time that a hexagonal perovskite, BaNiO3, can be a highly functional catalyst for OER in alkaline media. We demonstrate that the BaNiO3 performs OER activity at least an order of magnitude higher than an IrO2 catalyst. Using integrated density functional theory calculations and experimental validations, we unveil that the underlying mechanism originates from structural transformation from BaNiO3 to BaNi(0.83)O(2.5) (Ba6Ni5O15) over the OER cycling process. PMID:26910187

  18. Elemental analysis of BaTi0.96Fe0.04O3 & BaTi0.96Co0.04O3

    NASA Astrophysics Data System (ADS)

    Mishra, Ashutosh; Mishra, Niyati; Mahalakshmi, Kanaka; Bisen, Supriya

    2014-09-01

    A finest possible sample of 4% Iron doped & cobalt doped BaTiO3 (BTO) with possible tetragonal & cubic structure via solid state route was prepared. Prepared samples were characterized by X-ray diffraction (XRD) using by Bruker D8 advance XRD instrument, the value of 2Θ is in between 200 to 800. X-ray photoelectron spectroscopy (XPS) spectra were measured using a VSW Scientific instruments at UGC-DAE CSR.

  19. Atomized BaF2-CaF7 for Better-Flowing Plasma-Spray Feedstock

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Stanford, Malcolm K.

    2008-01-01

    Atomization of a molten mixture of BaF2 and CaF2 has been found to be superior to crushing of bulk solid BaF2- CaF2 as a means of producing eutectic BaF2-CaF2 powder for use as an ingredient of the powder feedstock of a high-temperature solid lubricant material known as PS304. Developed to reduce friction and wear in turbomachines that incorporate foil air bearings, PS304 is applied to metal substrates by plasma spraying. The constituents of PS304 are: a) An alloy of 80 weight percent Ni and 20 weight percent Cr, b) Cr2O3, c) Ag, and d) The BaF2-CaF2 eutectic, specifically, 62 weight percent BaF2 and 38 weight percent CaF2. The superiority of atomization as a means of producing the eutectic BaF2-CaF2 powder lies in (1) the shapes of the BaF2-CaF2 particles produced and (2) the resulting flow properties of the PS304 feedstock powder: The particles produced through crushing are angular, whereas those produced through atomization are more rounded. PS304 feedstock powder containing the more rounded BaF2-CaF2 particles flows more freely and more predictably, as is preferable for plasma spraying.

  20. Draft Genome Sequence of Photorhabdus luminescens Strain BA1, an Entomopathogenic Bacterium Isolated from Nematodes Found in Egypt.

    PubMed

    Ghazal, Shimaa; Hurst, Sheldon G; Morris, Krystalynne; Abebe-Akele, Feseha; Thomas, W Kelley; Badr, Usama M; Hussein, Mona A; Abouzaied, Mohamed A; Khalil, Kamal M; Tisa, Louis S

    2014-01-01

    Photorhabdus luminescens strain BA1 is an entomopathogenic bacterium that forms a symbiotic association with Heterorhabditis nematodes. We report here a 5.0-Mbp draft genome sequence for P. luminscens strain BA1, with a G+C content of 42.46% and 4,250 candidate protein-coding genes. PMID:24786955

  1. Baumot BA-B Diesel Particulate Filter with Pre-Catalyst (ETV Mobile Source Emissions Control Devices) Verification Report

    EPA Science Inventory

    The Baumot BA-B Diesel Particulate Filter with Pre-Catalyst is a diesel engine retrofit device for light, medium, and heavy heavy-duty diesel on-highway engines for use with commercial ultra-low-sulfur diesel (ULSD) fuel. The BA-B particulate filter is composed of a pre-catalyst ...

  2. Structural insights into the thermal decomposition sequence of barium tetrahydrogenorthotellurate(VI), Ba[H4TeO6

    NASA Astrophysics Data System (ADS)

    Weil, Matthias; Stöger, Berthold; Gierl-Mayer, Christian; Libowitzky, Eugen

    2016-09-01

    The compounds Ba[H4TeO6] (I), Ba[H2TeO5] (II), Ba[Te2O6(OH)2] (III) and Ba[TeO4] (IV) were prepared by application of a diffusion method (I), under hydrothermal conditions (II and III) and from solid state reactions (IV), respectively. Structure analysis on the basis of single crystal X-ray diffraction data revealed novel structure types for (I), (II) and (III) and isotypism of (IV) with PrSbO4 and LaSbO4. Common feature of the four oxotellurate(VI) structures are [TeO6] octahedra. Whereas in the crystal structure of (I) the octahedral units are isolated, they are condensed into chains via corner-sharing in (II) and via edge-sharing in (III) and (IV). The coordination numbers of the barium cations in the four structures range from seven to ten. Although hydrogen atom positions could not be located for the structures of (I) and (II), short interpolyhedral O···O contacts are evident for strong hydrogen bonding. The temperature behaviour of (I), (II) and (IV) was monitored by simultaneous thermal analysis (STA) measurements and in situ powder X-ray diffraction, revealing the decomposition sequence Ba[H4TeO6] → Ba[H2TeO5] → Ba[TeO4]→ Ba[TeO3] upon heating to temperatures up to 900 °C.

  3. The Role of Area 10 (BA10) in Human Multitasking and in Social Cognition: A Lesion Study

    ERIC Educational Resources Information Center

    Roca, Maria; Torralva, Teresa; Gleichgerrcht, Ezequiel; Woolgar, Alexandra; Thompson, Russell; Duncan, John; Manes, Facundo

    2011-01-01

    A role for rostral prefrontal cortex (BA10) has been proposed in multitasking, in particular, the selection and maintenance of higher order internal goals while other sub-goals are being performed. BA10 has also been implicated in the ability to infer someone else's feelings and thoughts, often referred to as theory of mind. While most of the data…

  4. Modification of microsomal metabolism of benzo(a)pyrene (BaP) by superoxide generated in vitro

    SciTech Connect

    Byczkowski, J.Z.; Gessner, T.

    1986-03-01

    Reactive oxygen species may play a role in bioactivation of BaP and its procarcinogenic metabolites. The effect of superoxide (O/sub 2/) and/or other active oxygen species, generated in vitro by xanthine/xanthine oxidase (X/XO) +/- Fe/sup 3 +/, on BaP metabolism by mouse liver microsomes fortified with NADPH and UDP-glucuronic acid was examined. Analysis of the reaction mixtures by reversed-phase high pressure liquid chromatography in methanol-water gradient showed that the peroxidative conditions evoked by X/XO + Fe/sup 3 +/ decreased the overall metabolism of /sup 14/C-BaP by some 40% and decreased glucuronidation of BaP metabolites by about 85%, while protein bound metabolites increased by 80%. Even without added Fe/sup 3 +/, O/sub 2/ increased the production of epoxides by 174%. Addition of superoxide dismutase reversed the decreases in both glucuronidation and overall metabolism of BaP. This indicates that O/sub 2/ switches the BaP metabolism to direct epoxidation and increases the amount of intermediates able to bind protein, while damage to membrane bound enzymes curtails further metabolism of BaP. Thus, it appears that during oxidative burst, such as in inflammatory reactions, there would be a limited mixed function oxidase mediated bioactivation of BaP.

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

    SciTech Connect

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

    2015-01-15

    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{sub 6}, SrB{sub 6}, BaB{sub 6} and the ternary hexaborides Ca{sub x}Sr{sub 1−x}B{sub 6}, Ca{sub x}Ba{sub 1−x}B{sub 6}, Sr{sub x}Ba{sub 1−x}B{sub 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{sub 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.

  6. 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

    SciTech Connect

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

    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)

  7. A thermodynamic study of BaO + BaCl[sub 2] + Cr[sub 2]O[sub 3] fluxes used for the removal of phosphorus from chromium-containing iron melts

    SciTech Connect

    Inouye, T.K.; Fujiwara, H.; Ichise, E.; Iwase, M. )

    1994-10-01

    Electrochemical measurements with solid-oxide galvanic cell of the type Mo/Mo + MoO[sub 2]//ZrO[sub 2](MgO)//(Cu + Cr)[sub alloy] + (Cr[sub 2]O[sub 3])[sub slag]/Mo were conducted at 1,473 K in order to obtain the activities of Cr[sub 2]O[sub 3] in BaO + BaCl[sub 2] + Cr[sub 2]O[sub 3] slags used for dephosphorization of chromium-containing iron melts. Based on the activity measurements, it is concluded that in the system BaO + BaCl[sub 2] + Cr[sub 2]O[sub 3] at 1,473 K, there are 1 two-phase region in saturation with pure Cr[sub 2]O[sub 3](s) and 3 three-phase regions. The activities of Cr[sub 2]O[sub 3] within such three-phase regions decrease with an increase in BaO/BaCl[sub 2] mole ratios. The Cr[sub 2]O[sub 3] activities in BaO + BaCl[sub 2] + Cr[sub 2]O[sub 3] fluxes are, in general, greater than those in CaO + CaCl[sub 2] + Cr[sub 2]O[sub 3], corresponding to much more effective dephosphorization by BaO + BaCl[sub 2] + Cr[sub 2]O[sub 3] fluxes rather than CaO + CaCl[sub 2] + Cr[sub 2]O[sub 3] slag.

  8. Ca, Sr and Ba stable isotopes reveal the fate of soil nutrients along a tropical climosequence

    USGS Publications Warehouse

    Bullen, Thomas D.; Chadwick, Oliver A.

    2016-01-01

    Nutrient biolifting is an important pedogenic process in which plant roots obtain inorganic nutrients such as phosphorus (P) and calcium (Ca) from minerals at depth and concentrate those nutrients at the surface. Here we use soil chemistry and stable isotopes of the alkaline earth elements Ca, strontium (Sr) and barium (Ba) to test the hypothesis that biolifting of P has been an important pedogenic process across a soil climosequence developed on volcanic deposits at Kohala Mountain, Hawaii. The geochemical linkage between these elements is revealed as generally positive site-specific relationships in soil mass gains and losses, particularly for P, Ba and Ca, using the ratio of immobile elements titanium and niobium (Ti/Nb) to link individual soil samples to a restricted compositional range of the chemically and isotopically diverse volcanic parent materials. At sites where P is enriched in surface soils relative to abundances in deeper soils, the isotope compositions of exchangeable Ca, Sr and Ba in the shallowest soil horizons (< 10 cm depth) are lighter than those of the volcanic parent materials and trend toward those of plants growing on fresh volcanic deposits. In contrast the isotope composition of exchangeable Ba in deeper soil horizons (> 10 cm depth) at those sites is consistently heavier than the volcanic parent materials. The isotope compositions of exchangeable Ca and Sr trend toward heavier compositions with depth more gradually, reflecting increasing leakiness from these soils in the order Ba < Sr < Ca and downward transfer of light biocycled Ca and Sr to deeper exchange sites. Given the long-term stability of ecosystem properties at the sites where P is enriched in surface soils, a simple box model demonstrates that persistence of isotopically light exchangeable Ca, Sr and Ba in the shallowest soil horizons requires that the uptake flux to plants from those near-surface layers is less than the recycling flux returned to the surface as

  9. EROD activity and genotoxicity in the seabob shrimp Xiphopenaeus kroyeri exposed to benzo[a]pyrene (BaP) concentrations.

    PubMed

    da Silva Rocha, Arthur José; Gomes, Vicente; Rocha Passos, Maria José de Arruda Campos; Hasue, Fabio Matsu; Alves Santos, Thaís Cruz; Bícego, Márcia Caruso; Taniguchi, Satie; Van Ngan, Phan

    2012-11-01

    Seabob shrimp Xiphopenaeus kroyeri is a marine species that lives in shallow waters of coastal environments, often impacted by polycyclic aromatic hydrocarbons (PAH) pollution. In the present study, seabob shrimp were exposed for 96 h to benzo[a]pyrene (BaP) at the nominal concentrations of 100, 200, 400 and 800 microg-L(-1). Animals of the control groups were exposed either to clean water or to the BaP-carrier (DMSO). At the end of the exposures, muscle tissues were sampled for BaP uptake assessment and hepatopancreas and hemolymph for EROD enzyme activity and hemocytes DNA damage, respectively. EROD activity and DNA damage increased significantly as a function of BaP exposure concentrations. Significant correlations between BaP uptake and both EROD activity and DNA damage suggest that they can be used as suitable tools for integrated levels of study on the biomarkers of PAH exposure.

  10. Cyclic MAM synthesis of SPION/BaMoO4:Er3+,Yb3+ composite and its optical properties

    NASA Astrophysics Data System (ADS)

    Lim, C. S.; Atuchin, V. V.

    2013-05-01

    Er3+/Yb3+ co-doped BaMoO4 (BaMoO4:Er3+/Yb3+) composites with superparamagnetic iron oxide nanoparticles (SPIONs) incorporated were successfully synthesized by a cyclic microwave-assisted metathetic (MAM) method followed by heat-treatment. The microstructure exhibited well-defined and homogeneous morphology with the BaMoO4:Er3+/Yb3+ particle size of 1-2 μm and Fe3O4 particle size of 0.1-0.5 μm. The Fe3O4 particles were self-preferentially crystallized and immobilized on the surface of BaMoO4:Er3+/Yb3+ particles. The synthesized SPION/BaMoO4:Er3+,Yb3+ composites were characterized by X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Optical properties were examined using photoluminescence emission measurements and Raman spectroscopy.

  11. Nematic magnetoelastic effect contrasted between Ba (Fe1 -xCox)2As2 and FeSe

    NASA Astrophysics Data System (ADS)

    Hu, Yuwen; Ren, Xiao; Zhang, Rui; Luo, Huiqian; Kasahara, Shigeru; Watashige, Tatsuya; Shibauchi, Takasada; Dai, Pengcheng; Zhang, Yan; Matsuda, Yuji; Li, Yuan

    2016-02-01

    To elucidate the origin of nematic order in Fe-based superconductors, we report a Raman scattering study of lattice dynamics, which quantify the extent of C4-symmetry breaking, in BaFe2As2 and FeSe. FeSe possesses a nematic ordering temperature Ts and orbital-related band-energy split below Ts that are similar to those in BaFe2As2 , but unlike BaFe2As2 it has no long-range magnetic order. We find that the Eg phonon-energy split in FeSe becomes substantial only well below Ts, and its saturated value is much smaller than that in BaFe2As2 . Together with reported results for the Ba (Fe1 -xCox)2As2 family, the data suggest that magnetism exerts a major influence on the lattice.

  12. BaO/W(100) thermionic emitters and the effects of Sc, Y, La, and the density functional used in computations.

    SciTech Connect

    Zavadil, Kevin Robert; King, Donald Bryan; Schultz, Peter Andrew; Jennison, Dwight Richard

    2003-06-01

    Density functional theory is used to predict workfunctions, {psi}. For relaxed clean W(1 0 0), the local density approximation (LDA) agrees with experiment better than the newer generalized gradient approximation, probably due to the surface electron self-energy. The large Ba metallic radius indicates it covers W(1 0 0) at about 0.5 monolayer (ML). However, Ba{sup 2+}, O{sup 2-}, and metallic W all have similar radii. Thus 1 ML of BaO (one BaO unit for each two W atoms) produces minimum strain, indicating commensurate interfaces. BaO (1 ML) and Ba (1/2 ML) have the same {psi} to within 0.02 V, so at these coverages reduction or oxidation is not important. Due to greater chemical activity of ScO vs. highly ionic BaO, when mixing the latter with this suboxide of scandia, the overlayer always has BaO as the top layer and ScO as the second layer. The BaO/ScO bilayer has a rocksalt structure, suggesting high stability. In the series BaO/ScO/, BaO/YO/, and BaO/LaO/W(1 0 0), the latter has a remarkably low {psi} of 1.3 V (LDA), but 2 ML of rocksalt BaO also has {psi} at 1.3 V. We suggest BaO (1 ML) does not exist and that it is worthwhile to attempt the direct synthesis and study of BaO (2 ML) and BaO/LaO.

  13. Studies of local structural distortions in strained ultrathin BaTiO3 films using scanning transmission electron microscopy.

    PubMed

    Park, Daesung; Herpers, Anja; Menke, Tobias; Heidelmann, Markus; Houben, Lothar; Dittmann, Regina; Mayer, Joachim

    2014-06-01

    Ultrathin ferroelectric heterostructures (SrTiO3/BaTiO3/BaRuO3/SrRuO3) were studied by scanning transmission electron microscopy (STEM) in terms of structural distortions and atomic displacements. The TiO2-termination at the top interface of the BaTiO3 layer was changed into a BaO-termination by adding an additional BaRuO3 layer. High-angle annular dark-field (HAADF) imaging by aberration-corrected STEM revealed that an artificially introduced BaO-termination can be achieved by this interface engineering. By using fast sequential imaging and frame-by-frame drift correction, the effect of the specimen drift was significantly reduced and the signal-to-noise ratio of the HAADF images was improved. Thus, a quantitative analysis of the HAADF images was feasible, and an in-plane and out-of-plane lattice spacing of the BaTiO3 layer of 3.90 and 4.22 Å were determined. A 25 pm shift of the Ti columns from the center of the unit cell of BaTiO3 along the c-axis was observed. By spatially resolved electron energy-loss spectroscopy studies, a reduction of the crystal field splitting (CFS, ΔL3=1.93 eV) and an asymmetric broadening of the eg peak were observed in the BaTiO3 film. These results verify the presence of a ferroelectric polarization in the ultrathin BaTiO3 film.

  14. Removals of non-analogous OTC and BaP in AMCBR with and without primary substrate.

    PubMed

    Çelebi, Hakan; Gök, Oğuzhan; Sponza, Delia Teresa

    2016-01-01

    Anaerobic biodegradation of mixed non-analogous two substrates was studied in a binary system with and without the primary substrate using an anaerobic multichamber bed (AMCBR). In the binary mixture, the biodegradation of less-degradable oxytetracycline (OTC) was restarted in the presence of more degradable benzo[a]pyrene (BaP) in the initial runs of the AMCBR, but enhanced biodegradation of the more recalcitrant OTC occurs in the later runs of the AMCBR due to enhanced biomass growth on dual substrates without the primary carbon source. The biodegradation yields of the OTC, BaP were discussed with sole-substrate systems and with the dual substrate system in the presence of the primary substrate. The maximum OTC and BaP yields were 93% in Run 3 with the primary substrate, while the maximum BaP and OTC yields were 95%, 98% in Run 3 without the primary substrate. A dual form of the Monod was found to adequately predict the substrate interactions in the binary mixture of OTC and BaP using only the parameters derived from batch experiments. At low BaP (4 mg L(-1)) and OTC (40 mg L(-1)) concentrations, a non-competitive inhibition does not affect the binding of the substrate and so the K(s) were was not affected while the µ(max) was lowered. At high BaP (10 mg L(-1)) and OTC (100 mg L(-1)) concentrations, the BaP and OTC were biodegraded according to competitive inhibition with increased K(s) while µ(max) was not affected. BaP and OTC were biodegraded according to Haldane at high concentrations (>10 mg L(-1) for BaP, 100 mg L(-1) OTC) where they were used as the sole substrate.

  15. The use of 133 Ba+ as a new candidate for trapped atomic ion qubits

    NASA Astrophysics Data System (ADS)

    Hucul, David; Christiansen, Justin; Campbell, Wesley; Hudson, Eric

    2016-05-01

    Trapped atomic ions are qubit standards in quantum information science because of their long coherence times and high fidelity entangling gates. Many different atomic ions have been used as qubits, each with strengths and weaknesses dictated by its atomic structure. We propose to use 133 Ba+ as an atomic qubit. 133 Ba+ is a nearly ideal, all-purpose candidate by combining many of the strengths of different workhorse atomic ions. 133 Ba+, like 171 Yb+, has a nuclear spin 1/2, allowing for a robust hyperfine qubit with simple state preparation and readout via differential fluorescence. The lack of a low-lying F-state, like in Ca+, simplifies high-fidelity qubit state detection that relies on shelving a qubit level to a meta-stable excited state. In addition, 133 Ba+ can be used for background-free qubit state detection where the wavelength of the qubit detection light differs from all excitation light by at least 50 THz. Unlike all other ions in use, the optical transitions of barium are in the visible spectrum, enabling the use of high power lasers, low-loss fibers, high quantum efficiency detectors, and other technologies developed for visible wavelengths of light to ease some requirements toward scaling a quantum system.

  16. Chemical and orbital fluctuations in Ba3CuSb2O9

    NASA Astrophysics Data System (ADS)

    Wakabayashi, Yusuke; Nakajima, Daisuke; Ishiguro, Yuki; Kimura, Kenta; Kimura, Tsuyoshi; Tsutsui, Satoshi; Baron, Alfred Q. R.; Hayashi, Kouichi; Happo, Naohisa; Hosokawa, Shinya; Ohwada, Kenji; Nakatsuji, Satoru

    2016-06-01

    Structural fluctuation in Ba3CuSb2O9 , which is proposed to exhibit a spin-orbital entangled state, has been studied by diffuse x-ray scattering, x-ray fluorescence holography, and inelastic x-ray scattering. Two kinds of spatial fluctuations are observed: temperature-independent and temperature-dependent ones. The former is related to Cu/Sb arrangement. The short-range chemical correlation in Ba3CuSb2O9 is honeycomblike, whereas the correlation length is as short as the diameter of the honeycomb unit. The temperature variation of ferro- and antiferro-orbital correlations is extracted from Huang scattering intensity distributions. Both of these correlations increase with decreasing temperature down to 60 K, which corresponds to the energy of magnetic interaction of Ba3CuSb2O9 . A wide distribution of the characteristic time scale of the orbital motion is proposed from the spatial fluctuation of the ionic arrangement in Ba3CuSb2O9 .

  17. Synthesis and Structure Determination of Ferromagnetic Semiconductors LaAMnSnO6 (A = Sr Ba)

    SciTech Connect

    T Yang; T Perkisas; J Hadermann; M Croft; A Ignatov; M Greenblatt

    2011-12-31

    LaAMnSnO{sub 6} (A = Sr, Ba) have been synthesized by high temperature solid-state reactions under dynamic 1% H{sub 2}/Ar flow. Rietveld refinements on room temperature powder X-ray diffraction data indicate that LaSrMnSnO{sub 6} crystallizes in the GdFeO{sub 3}-structure, with space group Pnma and, combined with transmission electron microscopy, LaBaMnSnO{sub 6} in Imma. Both space groups are common in disordered double-perovskites. The Mn{sup 3+} and Sn{sup 4+} ions whose valence states were confirmed by X-ray absorption spectroscopy, are completely disordered over the B-sites and the BO{sub 6} octahedra are slightly distorted. LaAMnSnO{sub 6} are ferromagnetic semiconductors with a T{sub C} = 83 K for the Sr- and 66 K for the Ba-compound. The title compounds, together with the previously reported LaCaMnSnO{sub 6} provide an interesting example of progression from Pnma to Imma as the tolerance factor increases. An analysis of the relationship between space group and tolerance factor for the series LaAMnMO{sub 6} (A = Ca, Sr, Ba; M = Sn, Ru) provides a better understanding of the symmetry determination for double perovskites.

  18. Specification of hepatopancreas progenitors in zebrafish by hnf1ba and wnt2bb

    PubMed Central

    Lancman, Joseph J.; Zvenigorodsky, Natasha; Gates, Keith P.; Zhang, Danhua; Solomon, Keely; Humphrey, Rohan K.; Kuo, Taiyi; Setiawan, Linda; Verkade, Heather; Chi, Young-In; Jhala, Ulupi S.; Wright, Christopher V. E.; Stainier, Didier Y. R.; Dong, P. Duc Si

    2013-01-01

    Although the liver and ventral pancreas are thought to arise from a common multipotent progenitor pool, it is unclear whether these progenitors of the hepatopancreas system are specified by a common genetic mechanism. Efforts to determine the role of Hnf1b and Wnt signaling in this crucial process have been confounded by a combination of factors, including a narrow time frame for hepatopancreas specification, functional redundancy among Wnt ligands, and pleiotropic defects caused by either severe loss of Wnt signaling or Hnf1b function. Using a novel hypomorphic hnf1ba zebrafish mutant that exhibits pancreas hypoplasia, as observed in HNF1B monogenic diabetes, we show that hnf1ba plays essential roles in regulating β-cell number and pancreas specification, distinct from its function in regulating pancreas size and liver specification, respectively. By combining Hnf1ba partial loss of function with conditional loss of Wnt signaling, we uncover a crucial developmental window when these pathways synergize to specify the entire ventrally derived hepatopancreas progenitor population. Furthermore, our in vivo genetic studies demonstrate that hnf1ba generates a permissive domain for Wnt signaling activity in the foregut endoderm. Collectively, our findings provide a new model for HNF1B function, yield insight into pancreas and β-cell development, and suggest a new mechanism for hepatopancreatic specification. PMID:23720049

  19. Grain Growth Kinetics of BaTiO3 Nanocrystals During Calcining Process

    NASA Astrophysics Data System (ADS)

    Song, Xiao-lan; He, Xi; Yang, Hai-ping; Qu, Yi-xin; Qiu, Guan-zhou

    2008-06-01

    BaTiO3 nanocrystals were synthesized by sol-gel method using barium acetate (Ba(CH3COO)2) and tetra-butyl titanate (Ti(OC4H9)4) as raw materials. Xerogel precursors and products were characterized by means of thermogravimetric/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD) and transmission electron microscope (TEM). The influence of the calcination temperature and duration on the lattice constant, the lattice distortion, and the grain size of BaTiO3 nanocrystals was discussed based on the XRD results. The grain growth kinetics of BaTiO3 nanocrystals during the calcination process were simulated with a conventional grain growth model which only takes into account diffusion, and an isothermal model proposed by Qu and Song, which takes into account both diffusion and surface reactions. Using these models, the pre-exponential factor and the activation energy of the rate constant were estimated. The simulation results indicate that the isothermal model is superior to the conventional one in describing the grain growth process, implying that both diffusion and surface reactions play important roles in the grain growth process.

  20. SuperMemo; XIA LI BA REN (Macintosh Version 1.0).

    ERIC Educational Resources Information Center

    Wharton, Charlotte; Bourgerie, Dana S.

    1994-01-01

    Describes "SuperMemo," a memorization tool that uses an automated flashcard scheme that can include sound and graphics in the database of study items. Based on the learner's performance, "SuperMemo" schedules items to appear for review. Xia Li Ba Ren ("common person" in Chinese) is the name of a Chinese word processor that runs with a standard…

  1. Optical and magnetic properties of Ba5(BO3)3F single crystals.

    PubMed

    Yelisseyev, A P; Jiang, Xingxing; Solntsev, V P; Bekker, T B; Lin, Zheshuai

    2014-12-01

    Ba5(BO3)3F single crystals of high optical quality and up to 1.5 cm in diameter were grown. Its transparency range is 0.23 to 6.6 μm (on 10% level). Direct allowed electronic transitions at the Γ-point give band gap values of 5.31 and 5.40 eV at 300 and 80 K, respectively. Luminescence is excited in the near-edge absorption bands near 265 and 365 nm. X-ray irradiation induces an additional absorption in dominant 252, 317 and 710 nm bands. Combined electron spin-resonance spectroscopy and theoretical analysis allow one to associate the three absorption peaks with O(5-), O(1-) and e6(-) (fluorine vacancy), respectively. The original transparency is restored after heating the crystal to 400 K and charge carrier release from traps with ET = 0.87 eV and s = 10(12) s(-1). Dispersion curves for the refractive indices were calculated and Sellmeier equations were built. Theoretical analysis shows strong localization of the Ba 5s and F 2s orbitals, strong ionicity of the Ba cations and strong covalency of the B-O bond. The optical properties of Ba5(BO3)3F are dominantly determined by electron transitions within the (BO3)(3-) groups, despite the transition between barium and oxygen also having a little contribution. PMID:25322208

  2. Noncentrosymmetric selenide Ba4Ga4GeSe12: Synthesis, structure, and optical properties

    NASA Astrophysics Data System (ADS)

    Yin, Wenlong; Iyer, Abishek K.; Li, Chao; Lin, Xinsong; Yao, Jiyong; Mar, Arthur

    2016-09-01

    The selenide Ba4Ga4GeSe12, synthesized by reaction of BaSe, Ga2Se3, and GeSe2 at 1173 K, adopts a noncentrosymmetric tetragonal structure (space group P 4 bar21 c , Z=2, a=13.5468(4) Å, c=6.4915(2) Å) consisting of a three-dimensional network built from two types of corner-sharing MSe4 tetrahedra, with Ba cations occupying the intervening voids. It is isostructural to Pb4Ga4GeS12, Pb4Ga4GeSe12, and Ba4Ga4SnSe12, but differs subtly in site ordering. Structural refinements and bond valence sum analysis suggest partial disorder manifested by mixing of 0.75 Ga and 0.25 Ge within one tetrahedral site, and occupation of exclusively Ga within the other tetrahedral site. The optical band gap of 2.18(2) eV, measured from the UV/VIS/NIR diffuse reflectance spectrum, agrees with a calculated gap of 2.35 eV between valence and conduction bands and is consistent with the orange-yellow color of the crystals. Nonlinear optical measurements on powder samples revealed a weak second harmonic generation signal using 2.09 μm as the fundamental laser wavelength.

  3. Atomic and electronic structure of the ferroelectric BaTiO{sub 3}/Ge(001) interface

    SciTech Connect

    Fredrickson, Kurt D.; Ponath, Patrick; Posadas, Agham B.; Demkov, Alexander A.; McCartney, Martha R.; Smith, David J.; Aoki, Toshihiro

    2014-06-16

    In this study, we demonstrate the epitaxial growth of BaTiO{sub 3} on Ge(001) by molecular beam epitaxy using a thin Zintl template buffer layer. A combination of density functional theory, atomic-resolution electron microscopy and in situ photoemission spectroscopy is used to investigate the electronic properties and atomic structure of the BaTiO{sub 3}/Ge interface. Aberration-corrected scanning transmission electron micrographs reveal that the Ge(001) 2 × 1 surface reconstruction remains intact during the subsequent BaTiO{sub 3} growth, thereby enabling a choice to be made between several theoretically predicted interface structures. The measured valence band offset of 2.7 eV matches well with the theoretical value of 2.5 eV based on the model structure for an in-plane-polarized interface. The agreement between the calculated and measured band offsets, which are highly sensitive to the detailed atomic arrangement, indicates that the most likely BaTiO{sub 3}/Ge(001) interface structure has been identified.

  4. Enhanced emissions in Tb3+-doped oxyfluoride scintillating glass ceramics containing BaF2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Huang, Lihui; Jia, Shijie; Li, Yang; Zhao, Shilong; Deng, Degang; Wang, Huanping; Jia, Guohua; Hua, Youjie; Xu, Shiqing

    2015-07-01

    Transparent Tb3+-doped glass ceramics containing BaF2 nanocrystals were prepared by melt-quenching method with subsequent heat treatment. The XRD and EDS results showed the precipitated crystalline phase in the glass matrix was BaF2. Under 376 nm light, Tb3+ doped oxyfluoride glass ceramics containing BaF2 nanocrystals showed more intense green emission than the as-made glass, and the emission intensity increased with increasing heat treatment temperature and time. The lifetimes of 541 nm emission of Tb3+ doped oxyfluoride glass ceramics were longer than that of as-made glass, which are in the range from 3.00 ms to 3.55 ms. Under X-ray excitation, the green emission was enhanced in the glass ceramics compared to the as-made glass. The results indicate Tb3+ doped oxyfluoride glass ceramics containing BaF2 nanocrystals could be a material candidate for X-ray glass scintillator for slow event detection.

  5. Measurements of electron excitation and recombination for Ne-like Ba/sup 46 +/

    SciTech Connect

    Marrs, R.E.; Levine, M.A.; Knapp, D.A.; Henderson, J.R.

    1987-07-01

    A new facility at Lawrence Livermore National Laboratory has been used to obtain measurements for electron-impact excitation, dielectronic recombination and radiative recombination for the neon-like Ba/sup 46 +/ ion. The experimental technique consists of trapping highly charged ions inside the space charge of an electron beam and measuring their x-ray emission spectra.

  6. A Learning Module for BA Students to Develop ICT Skills for Their Learning Activities

    ERIC Educational Resources Information Center

    Platteaux, Hervé; Hoein, Sergio

    2015-01-01

    This case illustrates the process of developing a learning module to support BA students in their use of ICT (Information and Communication Technology) tools in their learning. At the university where this case occurred, the skill level of ICT use among students in a learning context was very heterogeneous. The E-learning Competency Centre, or…

  7. mP-BaP₃: a new phase from an old binary system.

    PubMed

    Dolyniuk, Juli-Anna; Kaseman, Derrick C; Sen, Sabyasachi; Zhao, Jing; Osterloh, Frank E; Kovnir, Kirill

    2014-08-18

    A polyphosphide, mP-BaP3, with a unique two-dimensional phosphorus layer has been discovered and characterized. It crystallizes in the monoclinic space group P2₁/c with unit-cell parameters a=6.486(1), b=7.710(1), c=8.172(2) Å; β=104.72(3)°; Z=4. Its phosphorus polyanion can be derived from the strong elongation of 2/3 of the P-P bonds present in the layers of black phosphorus. The unit-cell volume of the mP-BaP3 phase is 1.4% larger than the volume of another polymorph, mS-BaP3, reported more than 40 years ago. The latter phase features the presence of one-dimensional phosphorus chains separated by Ba atoms. The differences in the structures of the phosphorus fragments in both polymorphs of barium triphosphide result in large differences in both the thermal stability of these materials as well as in their properties as evidenced by DSC, (31)P solid-state MAS NMR, UV/Vis, and surface photovoltage spectroscopies, alongside quantum-chemical calculations.

  8. Ba STARS AND OTHER BINARIES IN FIRST AND SECOND GENERATION STARS IN GLOBULAR CLUSTERS

    SciTech Connect

    D'Orazi, Valentina; Gratton, Raffaele; Lucatello, Sara; Carretta, Eugenio; Bragaglia, Angela; Marino, Anna F.

    2010-08-20

    The determination of the Ba abundance in globular cluster (GC) stars is a very powerful test to address several issues in the framework of multiple population scenarios. We measured the Ba content for a sample of more than 1200 stars in 15 Galactic GCs, using high-resolution FLAMES/Giraffe spectra. We found no variation in [Ba/Fe] ratios for different stellar populations within each cluster; this means that low-mass asymptotic giant branch stars do not significantly contribute to the intracluster pollution. Very interestingly, we found that the fraction of Ba stars in first generation (FG) stars is close to the values derived for field stars ({approx}2%); on the other hand, second generation (SG) stars present a significantly lower fraction. An independent and successful test, based on radial velocity variations among giant stars in NGC 6121, confirms our finding: the binary fraction among FG stars is about {approx}12%, to be compared with {approx}1% of SG stars. This is an evidence that SG stars formed in a denser environment, where infant mortality of binary systems was particularly efficient.

  9. Improvement of Gd123 superconductor bulks with the additions of BaFe12O19

    NASA Astrophysics Data System (ADS)

    Zhang, Yufeng; Peng, Liqi; Zhou, Wenli; Zhou, Xiaojuan; Jia, Lingling; Izumi, Mitsuru

    2015-07-01

    The flux pinning performance of the superconductors is important for the application of the Gd123 bulk superconductors. The study shows that to introduce the secondary phases into the Gd123 bulk matrix can enhance the flux pinning performance. In this article, by using top-seeding melt texture growth process method, single domain GdBa2Cu3O7-δ superconductor bulks doping with the different amounts of BaFe12O19 (0.0mol% to 0.8mol%) were successfully achieved. The property and micro-structure have also been investigated. The result shows that there is an obvious improvement on JC with 0.2mol% BaFe12O19 addition. The fine distribution and smaller size of Gd211 particles appear in the micro-structure which may result in the enhancement of JC. At the same time, BaFe12O19 may also form an effective pinning center to increase JC.

  10. Rare Hadronic and Radiative Penguin B Decays at BaBar

    SciTech Connect

    Willocq, Stephane

    2002-02-07

    We report recent results in the study of rare hadronic and radiative penguin decays of B mesons. These results are based on a sample of 23 million BB pairs collected by the BaBar Collaboration at the SLAC PEP-II e+e- B Factory.

  11. The theoretical 3D structure of Bacillus thuringiensis Cry5Ba.

    PubMed

    Xia, Li-Qiu; Zhao, Xin-Min; Ding, Xue-Zhi; Wang, Fa-Xiang; Sun, Yun-Jun

    2008-09-01

    Cry5Ba is a delta-endotoxin produced by Bacillus thuringiensis PS86A1 NRRL B-18900. It is active against nematodes and has great potential for nematode control. Here, we predict the first theoretical model of the three-dimensional (3D) structure of a Cry5Ba toxin by homology modeling on the structure of the Cry1Aa toxin, which is specific to Lepidopteran insects. Cry5Ba resembles the previously reported Cry1Aa toxin structure in that they share a common 3D structure with three domains, but there are some distinctions, with the main differences being located in the loops of domain I. Cry5Ba exhibits a changeable extending conformation structure, and this special structure may also be involved in pore-forming and specificity determination. A fuller understanding of the 3D structure will be helpful in the design of mutagenesis experiments aimed at improving toxicity, and lead to a deep understanding of the mechanism of action of nematicidal toxins.

  12. Optical observation of spin-density-wave fluctuations in Ba122 iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Xu, B.; Dai, Y. M.; Xiao, H.; Shen, B.; Ye, Z. R.; Forget, A.; Colson, D.; Feng, D. L.; Wen, H. H.; Qiu, X. G.; Lobo, R. P. S. M.

    2016-08-01

    In iron-based superconductors, a spin-density-wave (SDW) magnetic order is suppressed with doping, and unconventional superconductivity appears in close proximity to the SDW instability. The optical response of the SDW order shows clear gap features: substantial suppression in the low-frequency optical conductivity, alongside a spectral weight transfer from low to high frequencies. Here, we study the detailed temperature dependence of the optical response in three different series of the Ba122 system [Ba1 -xKxFe2As2 , Ba (Fe1-xCox) 2As2 , and BaFe2(As1-xPx) 2 ]. Intriguingly, we find that the suppression of the low-frequency optical conductivity and spectral weight transfer appear at a temperature T* much higher than the SDW transition temperature TSDW. Since this behavior has the same optical feature and energy scale as the SDW order, we attribute it to SDW fluctuations. Furthermore, T* is suppressed with doping, closely following the doping dependence of the nematic fluctuations detected by other techniques. These results suggest that the magnetic and nematic orders have an intimate relationship, in favor of the magnetic-fluctuation-driven nematicity scenario in iron-based superconductors.

  13. Polygyny without wealth: popularity in gift games predicts polygyny in BaYaka Pygmies

    PubMed Central

    Chaudhary, Nikhil; Salali, Gul Deniz; Thompson, James; Dyble, Mark; Page, Abigail; Smith, Daniel; Mace, Ruth; Migliano, Andrea Bamberg

    2015-01-01

    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. PMID:26064662

  14. (228)Ra and (226)Ra measurement on a BaSO4 co-precipitation source.

    PubMed

    Medley, Peter; Martin, Paul; Bollhöfer, Andreas; Parry, David

    2014-10-14

    One of the most commonly-used methods for determination of (226)Ra, particularly in water samples, utilises co-precipitation of Ra with BaSO4, followed by microfiltration to produce a source for alpha counting. This paper describes two extensions to BaSO4 co-precipitation methods which enable determination of (228)Ra using the same source. The adaptations presented here do not introduce any contaminants that will affect the separation of radium or alpha counting for (226)Ra, and can be used for re-analysis of already existing sources prepared by BaSO4 co-precipitation. The first adaptation uses detection of (228)Ac on the source by gamma spectrometry. The detection efficiency is high, allowing analysis of water samples at sufficiently low activity to be suitable in testing for compliance with drinking water quality standards. As (228)Ac grows in quickly, taking less than 2 days to reach equilibrium with the (228)Ra parent, this can also be useful in radiological emergency response situations. The second adaptation incorporates a method for the digestion of BaSO4 sources, allowing separation of thorium and subsequent determination of (228)Th activity. Although ingrowth periods for (228)Th can be lengthy, very low detection limits for (228)Ra can be achieved with this technique.

  15. RssAB-FlhDC-ShlBA as a major pathogenesis pathway in Serratia marcescens.

    PubMed

    Lin, Chuan-Sheng; Horng, Jim-Tong; Yang, Chun-Hung; Tsai, Yu-Huan; Su, Lin-Hui; Wei, Chia-Fong; Chen, Chang-Chieh; Hsieh, Shang-Chen; Lu, Chia-Chen; Lai, Hsin-Chih

    2010-11-01

    Serratia marcescens has long been recognized as an important opportunistic pathogen, but the underlying pathogenesis mechanism is not completely clear. Here, we report a key pathogenesis pathway in S. marcescens comprising the RssAB two-component system and its downstream elements, FlhDC and the dominant virulence factor hemolysin ShlBA. Expression of shlBA is under the positive control of FlhDC, which is repressed by RssAB signaling. At 37°C, functional RssAB inhibits swarming, represses hemolysin production, and promotes S. marcescens biofilm formation. In comparison, when rssBA is deleted, S. marcescens displays aberrant multicellularity favoring motile swarming with unbridled hemolysin production. Cellular and animal infection models further demonstrate that loss of rssBA transforms this opportunistic pathogen into hypervirulent phenotypes, leading to extensive inflammatory responses coupled with destructive and systemic infection. Hemolysin production is essential in this context. Collectively, a major virulence regulatory pathway is identified in S. marcescens.

  16. KrF laser-induced ablation and patterning of Y--Ba--Cu--O films

    SciTech Connect

    Heitz, J.; Wang, X.Z.; Schwab, P.; Baeuerle, D. ); Schultz, L. )

    1990-09-01

    The ablation and patterning of Y--Ba--Cu--O films on (100) SrTiO{sub 3} and (100) MgO substrates by KrF excimer-laser light projection was investigated. Three different regimes of laser-material interactions were observed. Transition temperatures and critical current densities in laser-fabricated strip lines were investigated.

  17. (228)Ra and (226)Ra measurement on a BaSO4 co-precipitation source.

    PubMed

    Medley, Peter; Martin, Paul; Bollhöfer, Andreas; Parry, David

    2014-10-14

    One of the most commonly-used methods for determination of (226)Ra, particularly in water samples, utilises co-precipitation of Ra with BaSO4, followed by microfiltration to produce a source for alpha counting. This paper describes two extensions to BaSO4 co-precipitation methods which enable determination of (228)Ra using the same source. The adaptations presented here do not introduce any contaminants that will affect the separation of radium or alpha counting for (226)Ra, and can be used for re-analysis of already existing sources prepared by BaSO4 co-precipitation. The first adaptation uses detection of (228)Ac on the source by gamma spectrometry. The detection efficiency is high, allowing analysis of water samples at sufficiently low activity to be suitable in testing for compliance with drinking water quality standards. As (228)Ac grows in quickly, taking less than 2 days to reach equilibrium with the (228)Ra parent, this can also be useful in radiological emergency response situations. The second adaptation incorporates a method for the digestion of BaSO4 sources, allowing separation of thorium and subsequent determination of (228)Th activity. Although ingrowth periods for (228)Th can be lengthy, very low detection limits for (228)Ra can be achieved with this technique. PMID:25464199

  18. Giant thermal vibrations in the framework compounds Ba1 -xSrxAl2O4

    NASA Astrophysics Data System (ADS)

    Kawaguchi, S.; Ishii, Y.; Tanaka, E.; Tsukasaki, H.; Kubota, Y.; Mori, S.

    2016-08-01

    Synchrotron x-ray diffraction experiments were performed on the network compounds Ba1 -xSrxAl2O4 at temperatures between 15 and 800 K. The ferroelectric phase of the parent BaAl2O4 is largely suppressed by substituting a small amount of Sr for Ba and disappears for x ≥0.1 . Structural refinements reveal that the isotropic atomic displacement parameter Biso in the bridging oxygen atom is largely independent of temperature and retains an anomalously large value in the adjacent paraelectric phase even at the lowest temperature. The Biso systematically increases as x increases, exhibiting an especially large value for x =0.5 . According to previous electron diffraction experiments for Ba1 -xSrxAl2O4 with x ≥0.1 , strong thermal diffuse scattering occurs at two reciprocal points relating to two distinct soft modes at the M and K points over a wide range of temperatures below 800 K [Y. Ishii et al., Sci. Rep. 6, 19154 (2016), 10.1038/srep19154]. Although the latter mode disappears at approximately 200 K, the former does not condense, at least down to 100 K. The anomalously large Biso observed in this study is ascribed to these soft modes existing in a wide temperature range.

  19. High-temperature electronic transport properties of (YCa)BaCo4O7 compounds

    NASA Astrophysics Data System (ADS)

    Hao, Haoshan; He, Qinglin; Cheng, Yongguang; Zhao, Limin

    2014-04-01

    Y1-xCaxBaCo4O7 (0.0≤x≤1.0) samples were prepared by the solid-state reaction method and their high-temperature electronic transport properties were investigated in nitrogen and oxygen respectively. Phase structure of Y1-xCaxBaCo4O7 transforms from hexagonal symmetry for x ≤0.6 samples to orthorhombic symmetry for x≥0.8 samples. In nitrogen, Y1-xCaxBaCo4O7 samples evolve three kinds of electronic transport behaviors with the increase of Ca content: thermal activation conduction, small polaron hopping conduction, and a possible mixed conduction. Ca doping increases the hole concentration and thus decreases Seebeck coefficients. In oxygen, the temperature dependence of electrical resistivity and Seebeck coefficients of Y1-xCaxBaCo4O7 samples displays similar change to their respective thermogravimetric curve, showing their electronic transport behavior under the control of their oxygen adsoption/desorption process.

  20. Influence of metal ions on the order-disorder transition temperature of the Ba-M-O (M: La, Y, In, or Ga) system

    SciTech Connect

    Mitamura, Takashi; Ogino, Hiroyuki; Kobayashi, Hidehiko . Dept. of Applied Chemistry); Mori, Toshiyuki; Yamamura, Hiroshi . Tsukuba Research Lab.)

    1993-08-01

    Preparation of BaLa[sub 2]O[sub 4], Ba[sub 3]Y[sub 4]O[sub 9], Ba[sub 2]In[sub 2]O[sub 5], and Ba[sub 3]Ga[sub 2]O[sub 6] powders and their sintering were investigated in Ar or air. These sintered bodies with perovskite-related structure were synthesized by reaction sintering, using mixed powders in the atomic ratios of Ba/La = 1, Ba/Y = 0.75, Ba/In = 1, and Ba/Ga = 1.5. The order-disorder transition temperatures of the BaLa[sub 2]O[sub 4], Ba[sub 3]Y[sub 4]O[sub 9], Ba[sub 2]In[sub 2]O[sub 5], and Ba[sub 3]Ga[sub 2]O[sub 6], sintered bodies were 270, 350, 880, and 1,230 C, respectively. It was found that the temperatures were influenced by the ionic radius of cations in B sites, and the transition temperatures decreased with increasing ionic radius.