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  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 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

  3. 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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. 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

  5. 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

  6. Introducing new vaccines in the poorest countries: what did we learn from the GAVI experience with financial sustainability?

    PubMed

    Lydon, P; Levine, R; Makinen, M; Brenzel, L; Mitchell, V; Milstien, J B; Kamara, L; Landry, S

    2008-12-02

    This paper reviews the experience of the Global Alliance for Vaccines and Immunization (GAVI) in introducing hepatitis B and Haemophilus influenzae type b vaccines in the poorest countries, and explores how financing for immunization has changed since GAVI Fund resources were made available during its first wave of support between 2000 and 2006. The analysis of Financial Sustainability Plans in 50 countries allowed for some of the original funding assumptions of the GAVI approach to be tested against the realities in a wide set of countries, and to highlight implications for future immunization efforts. While the initial GAVI experience with financial sustainability has proved successful through the development of plans, and many countries have been able to both introduce new vaccines and mobilize additional financing for immunization, for future GAVI supported vaccine introduction, some country co-financing of these will be needed upfront for the approach to be more sustainable.

  7. Projected health and economic impact of rotavirus vaccination in GAVI-eligible countries: 2011-2030.

    PubMed

    Atherly, Deborah E; Lewis, Kristen D C; Tate, Jacqueline; Parashar, Umesh D; Rheingans, Richard D

    2012-04-27

    Rotavirus is the leading cause of diarrheal disease in children under 5 years of age. It is responsible for more than 450,000 deaths each year, with more than 90% of these deaths occurring in low-resource countries eligible for support by the GAVI Alliance. Significant efforts made by the Alliance and its partners are providing countries with the opportunity to introduce rotavirus vaccines into their national immunization programs, to help prevent childhood illness and death. We projected the cost-effectiveness and health impact of rotavirus vaccines in GAVI-eligible countries, to assist decision makers in prioritizing resources to achieve the greatest health benefits for their populations. A decision-analytic model was used to project the health outcomes and direct costs of a birth cohort in the target population, with and without a rotavirus vaccine. Current data on disease burden, vaccine efficacy, immunization rates, and costs were used in the model. Vaccination in GAVI-eligible countries would prevent 2.46 million childhood deaths and 83 million disability-adjusted life years (DALYs) from 2011 to 2030, with annual reductions of 180,000 childhood deaths at peak vaccine uptake. The cost per DALY averted is $42 for all GAVI countries combined, over the entire period. Rotavirus vaccination would be considered very cost-effective for the entire cohort of GAVI countries, and in each country individually, as cost-effectiveness ratios are less than the gross domestic product (GDP) per capita. Vaccination is most cost-effective and has the greatest impact in regions with high rotavirus mortality. Rotavirus vaccination in GAVI-eligible countries is very cost-effective and is projected to substantially reduce childhood mortality in this population. Copyright © 2012. Published by Elsevier Ltd.

  8. 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.

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

    PubMed

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

    2015-03-01

    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.

  10. GAVI and the Vaccine Fund--a boon for immunization in the developing world.

    PubMed

    Balaji, K A

    2004-01-01

    The Global Alliance for Vaccines and Immunization (GAVI) and The Vaccine Fund are two major global initiatives adopted with the objectives of improving access to immunization services particularly in the underdeveloped and developing countries and introduction of new but under-used vaccines in the developing countries in particular where these diseases are highly prevalent. GAVI is a collaborative mission that brings together governments in developing and industrialized countries, UNICEF, WHO, the World Bank, the Bill & Melinda Gates Foundation, vaccine manufacturers and all other stake holders to harness the strengths and experiences of multiple partners in immunization. The Vaccine Fund is a financing mechanism established to mobilize resources to serve the mission of GAVI. This article reviews the objectives, strategies, organization and the funding issues of this global initiative. In the Indian perspective, GAVI is presently playing a major role in introduction of Hepatitis-B vaccine for infants in India. The article outlined the pilot project currently being implemented by GoI and the future prospects of integrating Hepatitis-B vaccine and auto disable syringes into the routine immunization program as well as strengthening the routine immunization services when the government decides to expand the project.

  11. 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

  12. 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

  13. 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. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Evaluating Global Health Partnerships: A Case Study of a Gavi HPV Vaccine Application Process in Uganda

    PubMed Central

    Kamya, Carol; Shearer, Jessica; Asiimwe, Gilbert; Carnahan, Emily; Salisbury, Nicole; Waiswa, Peter; Brinkerhoff, Jennifer; Hozumi, Dai

    2017-01-01

    Background: Global health partnerships have grown rapidly in number and scope, yet there has been less emphasis on their evaluation. Gavi, the Vaccine Alliance, is one such public-private partnership; in Gavi-eligible countries partnerships are dynamic networks of immunization actors who work together to support all stages and aspects of Gavi support. This paper describes a conceptual framework – the partnership framework – and analytic approach for evaluating the perceptions of partnerships’ added value as well as the results from an application to one case in Uganda. Methods: We used a mixed-methods case study design embedded in the Gavi Full Country Evaluations (FCE) to test the partnership framework on Uganda’s human papillomavirus (HPV) vaccine application partnership. Data from document review, interviews, and social network surveys enabled the testing of the relationships between partnership framework domains (context, structure, practices, performance, and outcomes). Topic guides were based on the framework domains and network surveys identified working together relationships, professional trust, and perceptions of the effectiveness, efficiency, and legitimacy of the partnership’s role in this process. Results: Data from seven in-depth interviews, 11 network surveys and document review were analyzed according to the partnership framework, confirming relationships between the framework domains. Trust was an important contributor to the perceived effectiveness of the process. The network was structured around the EPI program, who was considered the leader of this process. While the structure and composition of the network was largely viewed as supporting an effective and legitimate process, the absence of the Ministry of Education (MoE) may have had downstream consequences if this study’s results had not been shared with the Ministry of Health (MoH) and acted upon. The partnership was not perceived to have increased the efficiency of the process

  15. Health and economic impact of rotavirus vaccination in GAVI-eligible countries.

    PubMed

    Kim, Sun-Young; Sweet, Steve; Slichter, David; Goldie, Sue J

    2010-05-14

    Rotavirus infection is responsible for about 500,000 deaths annually, and the disease burden is disproportionately borne by children in low-income countries. Recently the World Health Organization (WHO) has released a global recommendation that all countries include infant rotavirus vaccination in their national immunization programs. Our objective was to provide information on the expected health, economic and financial consequences of rotavirus vaccines in the 72 GAVI support-eligible countries. We synthesized population-level data from various sources (primarily from global-level databases) for the 72 countries eligible for the support by the GAVI Alliance (GAVI-eligible countries) in order to estimate the health and economic impact associated with rotavirus vaccination programs. The primary outcome measure was incremental cost (in 2005 international dollars [I$]) per disability-adjusted life year (DALY) averted. We also projected the expected reduction in rotavirus disease burden and financial resources required associated with a variety of scale-up scenarios. Under the base-case assumptions (70% coverage), vaccinating one single birth cohort would prevent about 55% of rotavirus associated deaths in the 72 GAVI-eligible countries. Assuming I$25 per vaccinated child (approximately $5 per dose), the number of countries with the incremental cost per DALY averted less than I$200 was 47. Using the WHO's cost-effectiveness threshold based on per capita GDP, the vaccines were considered cost-effective in 68 of the 72 countries (approximately 94%). A 10-year routine rotavirus vaccination would prevent 0.9-2.8 million rotavirus associated deaths among children under age 5 in the poorest parts of the world, depending on vaccine scale-up scenarios. Over the same intervention period, rotavirus vaccination programs would also prevent 4.5-13.3 million estimated cases of hospitalization and 41-107 million cases of outpatient clinic visits in the same population. Our findings

  16. 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

  17. Health and economic outcomes of HPV 16,18 vaccination in 72 GAVI-eligible countries.

    PubMed

    Goldie, Sue J; O'Shea, Meredith; Campos, Nicole Gastineau; Diaz, Mireia; Sweet, Steven; Kim, Sun-Young

    2008-07-29

    The risk of dying from cervical cancer is disproportionately borne by women in developing countries. Two new vaccines are highly effective in preventing HPV 16,18 infection, responsible for approximately 70% of cervical cancer, in girls not previously infected. The GAVI Alliance (GAVI) provides technical assistance and financial support for immunization in the world's poorest countries. Using population-based and epidemiologic data for 72 GAVI-eligible countries we estimate averted cervical cancer cases and deaths, disability-adjusted years of life (DALYs) averted and incremental cost-effectiveness ratios (I$/DALY averted) associated with HPV 16,18 vaccination of young adolescent girls. In addition to vaccine coverage and efficacy, relative and absolute cancer reduction depended on underlying incidence, proportion attributable to HPV types 16 and 18, population age-structure and competing mortality. With 70% coverage, mean reduction in the lifetime risk of cancer is below 40% in some countries (e.g., Nigeria, Ghana) and above 50% in others (e.g., India, Uganda, Kenya). At I$10 per vaccinated girl (approximately $2.00 per dose assuming three doses, plus wastage, administration, program support) vaccination was cost-effective in all countries using a per capita GDP threshold; for 49 of 72 countries, the cost per DALY averted was less than I$100 and for 59 countries, it was less than I$200. Taking into account country-specific assumptions (per capita GNI, DPT3 coverage, percentage of girls who are enrolled in fifth grade) for the year of introduction, percent coverage achieved in the first year, and years to maximum coverage, a 10-year modeled scenario prevented the future deaths of approximately 2 million women vaccinated as adolescents. Despite favorable cost-effectiveness, assessment of financial costs raised concerns about affordability; as the cost per vaccinated girl was increased from I$10 to I$25 (approximately $2 to $5 per dose), the financial costs for the

  18. 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).

  19. Charting the evolution of approaches employed by the Global Alliance for Vaccines and Immunizations (GAVI) to address inequities in access to immunization: a systematic qualitative review of GAVI policies, strategies and resource allocation mechanisms through an equity lens (1999-2014).

    PubMed

    Gandhi, Gian

    2015-11-30

    GAVI's focus on reducing inequities in access to vaccines, immunization, and GAVI funds, - both between and within countries - has changed over time. This paper charts that evolution. A systematic qualitative review was conducted by searching PubMed, Google Scholar and direct review of available GAVI Board papers, policies, and program guidelines. Documents were included if they described or evaluated GAVI policies, strategies, or programs and discussed equity of access to vaccines, utilization of immunization services, or GAVI funds in countries currently or previously eligible for GAVI support. Findings were grouped thematically, categorized into time periods covering GAVI's phases of operations, and assessed depending on whether the approaches mediated equity of opportunity or equity of outcomes between or within countries. Serches yielded 2816 documents for assessment. After pre-screening and removal of duplicates, 552 documents underwent detailed evaluation and pertinent information was extracted from 188 unique documents. As a global funding mechanism, GAVI responded rationally to a semi-fixed funding constraint by focusing on between-country equity in allocation of resources. GAVI's predominant focus and documented successes have been in addressing between-country inequities in access to vaccines comparing lower income (GAVI-eligible) countries with higher income (ineligible) countries. GAVI has had mixed results at addressing between-country inequities in utilization of immunization services, and has only more recently put greater emphasis and resources towards addressing within-country inequities in utilization to immunization services. Over time, GAVI has progressively added vaccines to its portfolio. This expansion should have addressed inter-country, inter-regional, inter-generational and gender inequities in disease burden, however, evidence is scant with respect to final outcomes. In its next phase of operations, the Alliance can continue to

  20. Exploring the influence of the Global Fund and the GAVI Alliance on health systems in conflict-affected countries.

    PubMed

    Patel, Preeti; Cummings, Rachael; Roberts, Bayard

    2015-01-01

    Global Health Initiatives (GHIs) respond to high-impact communicable diseases in resource-poor countries, including health systems support, and are major actors in global health. GHIs could play an important role in countries affected by armed conflict given these countries commonly have weak health systems and a high burden of communicable disease. The aim of this study is to explore the influence of two leading GHIs, the Global Fund and the GAVI Alliance, on the health systems of conflict-affected countries. This study used an analytical review approach to identify evidence on the role of the Global Fund and the GAVI Alliance with regards to health systems support to 19 conflict-affected countries. Primary and secondary published and grey literature were used, including country evaluations from the Global Fund and the GAVI Alliance. The WHO heath systems building blocks framework was used for the analysis. There is a limited evidence-base on the influence of GHIs on health systems of conflict-affected countries. The findings suggest that GHIs are increasingly investing in conflict-affected countries which has helped to rapidly scale up health services, strengthen human resources, improve procurement, and develop guidelines and protocols. Negative influences include distorting priorities within the health system, inequitable financing of disease-specific services over other health services, diverting staff away from more essential health care services, inadequate attention to capacity building, burdensome reporting requirements, and limited flexibility and responsiveness to the contextual challenges of conflict-affected countries. There is some evidence of increasing engagement of the Global Fund and the GAVI Alliance with health systems in conflict-affected countries, but this engagement should be supported by more context-specific policies and approaches.

  1. Landscaping the structures of GAVI country vaccine supply chains and testing the effects of radical redesign.

    PubMed

    Lee, Bruce Y; Connor, Diana L; Wateska, Angela R; Norman, Bryan A; Rajgopal, Jayant; Cakouros, Brigid E; Chen, Sheng-I; Claypool, Erin G; Haidari, Leila A; Karir, Veena; Leonard, Jim; Mueller, Leslie E; Paul, Proma; Schmitz, Michelle M; Welling, Joel S; Weng, Yu-Ting; Brown, Shawn T

    2015-08-26

    Many of the world's vaccine supply chains do not adequately provide vaccines, prompting several questions: how are vaccine supply chains currently structured, are these structures closely tailored to individual countries, and should these supply chains be radically redesigned? We segmented the 57 GAVI-eligible countries' vaccine supply chains based on their structure/morphology, analyzed whether these segments correlated with differences in country characteristics, and then utilized HERMES to develop a detailed simulation model of three sample countries' supply chains and explore the cost and impact of various alternative structures. The majority of supply chains (34 of 57) consist of four levels, despite serving a wide diversity of geographical areas and population sizes. These four-level supply chains loosely fall into three clusters [(1) 18 countries relatively more bottom-heavy, i.e., many more storage locations lower in the supply chain, (2) seven with relatively more storage locations in both top and lower levels, and (3) nine comparatively more top-heavy] which do not correlate closely with any of the country characteristics considered. For all three cluster types, our HERMES modeling found that simplified systems (a central location shipping directly to immunization locations with a limited number of Hubs in between) resulted in lower operating costs. A standard four-tier design template may have been followed for most countries and raises the possibility that simpler and more tailored designs may be warranted. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. 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. Project HOPE—The People-to-People Health Foundation, Inc.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. Lessons learned in shaping vaccine markets in low-income countries: a review of the vaccine market segment supported by the GAVI Alliance.

    PubMed

    Gilchrist, Shawn A N; Nanni, Angeline

    2013-12-01

    The Global Alliance for Vaccines and Immunization (GAVI) anticipated that growing demand for new vaccines could sufficiently impact the vaccines market to allow low-income countries (LICs) to self-finance new vaccines. But the time required to lower vaccine prices was underestimated and the amount that prices would decline overestimated. To better understand how prices in the LIC vaccine market can be impacted, the vaccine market was retrospectively examined. GAVI archives and the published literature on the vaccine markets in LICs were reviewed for the purpose of identifying GAVI's early assumptions for the evolution of vaccine prices, and contrasting these retrospectively with actual outcomes. The prices in Phases I and II of GAVI-supported vaccines failed to decline to a desirable level within a projected 5-year timeframe. GAVI-eligible countries were unable to sustain newly introduced vaccines without prolonged donor support. Two key lessons can be applied to future vaccine market-shaping strategies: (1) accurate demand forecasting together with committed donor funding can increase supply to the LIC vaccines market, but even greater strides can be made to increase the certainty of purchase; and (2) the expected time to lower prices took much longer than 5 years; market competition is inherently linked to the development time for new vaccines--a minimum of 5-10 or more years. Other factors that can lower vaccine prices include: large-scale production or alternate financing mechanisms that can hasten vaccine price maturation. The impacts of competition on vaccine prices in the LIC new-vaccines market occurred after almost 10 years. The time for research and development, acquisition of technological know-how and to scale production must be accounted for to more accurately predict significant declines on vaccine prices. Alternate financing mechanisms and the use of purchase agreements should also be considered for lowering prices when planning new vaccine

  8. A global health partnership's use of time-limited support to catalyze health practice change: the case of GAVI's Injection Safety Support.

    PubMed

    Levin, Ann; Fang, Arnold; Hansen, Peter M; Pyle, David; Dia, Ousmane; Schwalbe, Nina

    2010-09-27

    This paper presents the findings of a study to assess the effectiveness and sustainability of a GAVI (Global Alliance of Vaccines and Immunization) sponsored, time-limited Injection Safety (INS) support. The support came in two forms: 1) in-kind, in the form of AD syringes and safety boxes, and 2) in cash, for those countries that already had a secure, multi-year source of AD syringes and safety boxes, but proposed to use INS support to strengthen their injection safety activities. In total, GAVI gave INS support for a three-year period to 58 countries: 46 with commodities and 12 with cash support. To identify variables that might be associated with financial sustainability, frequencies and cross-tabulations were run against various programmatic and socio-economic variables in the 58 countries. All but two of the 46 commodity-recipient countries were able to replace and sustain the use of AD syringes and safety boxes after the end of their GAVI INS support despite the fact that standard disposable syringes are less costly than ADs (10-15 percent differential). In addition, all 12 cash-recipient countries continued to use AD syringes and safety boxes in their immunization programs in the years following GAVI INS assistance. At the same time, countries were often not prepared for the increased waste management requirements associated with the use of the syringes, suggesting the importance of anticipating challenges with the introduction of new technologies. The sustained use of AD syringes in countries receiving injection safety support from GAVI, in a majority of cases through government financing, following the completion of three years of time-limited support, represents an early indication of how GHPs can contribute to improved health outcomes in immunization safety in the world's poorest countries in a sustainable way.

  9. Performance-based financing with GAVI health system strengthening funding in rural Cambodia: a brief assessment of the impact.

    PubMed

    Matsuoka, Sadatoshi; Obara, Hiromi; Nagai, Mari; Murakami, Hitoshi; Chan Lon, Rasmey

    2014-07-01

    Though Cambodia made impressive gains in immunization coverage between the years 2000 and 2005, it recognized several health system challenges to greater coverage of immunization and sustainability. The Global Alliance for Vaccines and Immunization (GAVI) opened a Health System Strengthening (HSS) funding window in 2006. To address the health system challenges, Cambodia has been receiving the GAVI HSS fund since October 2007. The major component of the support is performance-based financing (PBF) for maternal, neonatal and child health (MNCH) services. To examine the impact of the PBF scheme on MNCH services and administrative management in rural Cambodia. Quantitative and qualitative studies were conducted in Kroch Chhmar Operational District (OD), Cambodia. Quantitative analyses were conducted on the trends of the numbers of MNCH services. A brief analysis was conducted using qualitative data. After the commencement of the PBF support, the volume of MNCH services was significantly boosted. In addition, strengthened financial and operational management was observed in the study area. However, the quality of the MNCH services was not ensured. Technical assistance, rather than the PBF scheme, was perceived by stakeholders to play a vital role in increasing the quality of the services. To improve the quality of the health services provided, it is better to include indicators on the quality of care in the PBF scheme. Mutual co-operation between PBF models and technical assistance may ensure better service quality while boosting the quantity. A robust but feasible data validation mechanism should be in place, as a PBF could incentivize inaccurate reporting. The capacity for financial management should be strengthened in PBF recipient ODs. To address the broader aspects of MNCH, a balanced input of resources and strengthening of all six building blocks of a health system are necessary. Published by Oxford University Press in association with The London School of Hygiene

  10. Paleolithic hominin remains from Eshkaft-e Gavi (southern Zagros Mountains, Iran): description, affinities, and evidence for butchery.

    PubMed

    Scott, Jeremiah E; Marean, Curtis W

    2009-09-01

    Eshkaft-e Gavi is a cave located in the southern Zagros Mountains of Iran and is one of the few archaeological sites in the region to preserve both Middle Paleolithic and Upper Paleolithic occupations. Excavation of the site in the 1970s yielded an assemblage of lithic and faunal remains, including ten hominin specimens: a mandibular molar, four cranial fragments, a clavicular diaphysis, the proximal half of a metacarpal, a fragment of os coxa, the proximal diaphysis of a juvenile femur, and a patella. The bones derive from a minimum of four individuals, including two juveniles. Although many of these remains could be Epi-Paleolithic in age, one of the juvenile specimens-the mandibular molar-occurs at the base of the cave's Upper Paleolithic sequence. The remains are very fragmentary, but those that preserve diagnostic morphology indicate that they represent modern humans. The molar is taxonomically diagnostic, thus confirming the association of the Aurignacian-like Baradostian Industry with modern humans. Four of the specimens-a piece of frontal bone, the clavicle, the juvenile femur, and the patella-display clear evidence for intentional butchery in the form of stone-tool cutmarks. These cutmarked specimens, along with a fragment of parietal bone, are also burned. Although this evidence is consistent with cannibalism, the small sample makes it difficult to say whether or not the individuals represented by the hominin remains were butchered and cooked for consumption. Nevertheless, the cutmarked Eshkaft-e Gavi specimens add to a growing sample of hominin remains extending back into the Plio-Pleistocene that display evidence of intentional defleshing.

  11. 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

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

    PubMed

    Ferrinho, Paulo; Dramé, Mohammed; Tumusiime, Prosper

    2013-01-01

    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. 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. 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. 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.

  13. The estimated mortality impact of vaccinations forecast to be administered during 2011-2020 in 73 countries supported by the GAVI Alliance.

    PubMed

    Lee, Lisa A; Franzel, Lauren; Atwell, Jessica; Datta, S Deblina; Friberg, Ingrid K; Goldie, Sue J; Reef, Susan E; Schwalbe, Nina; Simons, Emily; Strebel, Peter M; Sweet, Steven; Suraratdecha, Chutima; Tam, Yvonne; Vynnycky, Emilia; Walker, Neff; Walker, Damian G; Hansen, Peter M

    2013-04-18

    From August to December 2011, a multidisciplinary group with expertise in mathematical modeling was constituted by the GAVI Alliance and the Bill & Melinda Gates Foundation to estimate the impact of vaccination in 73 countries supported by the GAVI Alliance. The number of deaths averted in persons projected to be vaccinated during 2011-2020 was estimated for ten antigens: hepatitis B, yellow fever, Haemophilus influenzae type B (Hib), Streptococcus pneumoniae, rotavirus, Neisseria meningitidis serogroup A, Japanese encephalitis, human papillomavirus, measles, and rubella. Impact was calculated as the difference in the number of deaths expected over the lifetime of vaccinated cohorts compared to the number of deaths expected in those cohorts with no vaccination. Numbers of persons vaccinated were based on 2011 GAVI Strategic Demand Forecasts with projected dates of vaccine introductions, vaccination coverage, and target population size in each country. By 2020, nearly all GAVI-supported countries with endemic disease are projected to have introduced hepatitis B, Hib, pneumococcal, rotavirus, rubella, yellow fever, N. meningitidis serogroup A, and Japanese encephalitis-containing vaccines; 55 (75 percent) countries are projected to have introduced human papillomavirus vaccine. Projected use of these vaccines during 2011-2020 is expected to avert an estimated 9.9 million deaths. Routine and supplementary immunization activities with measles vaccine are expected to avert an additional 13.4 million deaths. Estimated numbers of deaths averted per 1000 persons vaccinated were highest for first-dose measles (16.5), human papillomavirus (15.1), and hepatitis B (8.3) vaccination. Approximately 52 percent of the expected deaths averted will be in Africa, 27 percent in Southeast Asia, and 13 percent in the Eastern Mediterranean. Vaccination of persons during 2011-2020 in 73 GAVI-eligible countries is expected to have substantial public health impact, particularly in Africa and

  14. Distributional impact of rotavirus vaccination in 25 GAVI countries: estimating disparities in benefits and cost-effectiveness.

    PubMed

    Rheingans, Richard; Atherly, Deborah; Anderson, John

    2012-04-27

    Other studies have demonstrated that the impact and cost effectiveness of rotavirus vaccination differs among countries, with greater mortality reduction benefits and lower cost-effectiveness ratios in low-income and high-mortality countries. This analysis combines the results of a country level model of rotavirus vaccination published elsewhere with data from Demographic and Health Surveys on within-country patterns of vaccine coverage and diarrhea mortality risk factors to estimate within-country distributional effects of rotavirus vaccination. The study examined 25 countries eligible for funding through the GAVI Alliance. For each country we estimate the benefits and cost-effectiveness of vaccination for each wealth quintile assuming current vaccination patterns and for a scenario where vaccine coverage is equalized to the highest quintile's coverage. In the case of India, variations in coverage and risk proxies by state were modeled to estimate geographic distributional effects. In all countries, rates of vaccination were highest and risks of mortality were lowest in the top two wealth quintiles. However countries differ greatly in the relative inequities in these two underlying variables. Similarly, in all countries examined, the cost-effectiveness ratio for vaccination ($/Disability-Adjusted Life Year averted, DALY) is substantially greater in the higher quintiles (ranging from 2-10 times higher). In all countries, the greatest potential benefit of vaccination was in the poorest quintiles. However, due to reduced vaccination coverage, projected benefits for these quintiles were often lower. Equitable coverage was estimated to result in an 89% increase in mortality reduction for the poorest quintile and a 38% increase overall. Rotavirus vaccination is most cost-effective in low-income groups and regions. However in many countries, simply adding new vaccines to existing systems targets investments to higher income children, due to disparities in vaccination

  15. Costs of Introducing and Delivering HPV Vaccines in Low and Lower Middle Income Countries: Inputs for GAVI Policy on Introduction Grant Support to Countries

    PubMed Central

    Levin, Ann; Wang, Susan A.; Levin, Carol; Tsu, Vivien; Hutubessy, Raymond

    2014-01-01

    Background In November 2011, the GAVI Alliance made the decision to add HPV vaccine as one of the new vaccines for which countries eligible for its funding (less than $1520 per capita income) could apply to receive support for national HPV vaccination, provided they could demonstrate the ability to deliver HPV vaccines. This paper describes the data and analysis shared with GAVI policymakers for this decision regarding GAVI HPV vaccine support. The paper reviews why strategies and costs for HPV vaccine delivery are different from other vaccines and what is known about the cost components from available data that originated primarily from HPV vaccine delivery costing studies in low and middle income-countries. Methods Financial costs of HPV vaccine delivery were compared across three sources of data: 1) vaccine delivery costing of pilot projects in five low and lower-middle income countries; 2) cost estimates of national HPV vaccination in two low income countries; and 3) actual expenditure data from national HPV vaccine introduction in a low income country. Both costs of resources required to introduce the vaccine (or initial one-time investment, such as cold chain equipment purchases) and recurrent (ongoing costs that repeat every year) costs, such as transport and health personnel time, were analyzed. The cost per dose, cost per fully immunized girl (FIG) and cost per eligible girl were compared across studies. Results Costs varied among pilot projects and estimates of national programs due to differences in scale and service delivery strategy. The average introduction costs per fully immunized girl ranged from $1.49 to $18.94 while recurrent costs per girl ranged from $1.00 to $15.69, with both types of costs varying by delivery strategy and country. Evaluating delivery costs along programme characteristics as well as country characteristics (population density, income/cost level, existing service delivery infrastructure) are likely the most informative and

  16. Costs of introducing and delivering HPV vaccines in low and lower middle income countries: inputs for GAVI policy on introduction grant support to countries.

    PubMed

    Levin, Ann; Wang, Susan A; Levin, Carol; Tsu, Vivien; Hutubessy, Raymond

    2014-01-01

    In November 2011, the GAVI Alliance made the decision to add HPV vaccine as one of the new vaccines for which countries eligible for its funding (less than $1520 per capita income) could apply to receive support for national HPV vaccination, provided they could demonstrate the ability to deliver HPV vaccines. This paper describes the data and analysis shared with GAVI policymakers for this decision regarding GAVI HPV vaccine support. The paper reviews why strategies and costs for HPV vaccine delivery are different from other vaccines and what is known about the cost components from available data that originated primarily from HPV vaccine delivery costing studies in low and middle income-countries. Financial costs of HPV vaccine delivery were compared across three sources of data: 1) vaccine delivery costing of pilot projects in five low and lower-middle income countries; 2) cost estimates of national HPV vaccination in two low income countries; and 3) actual expenditure data from national HPV vaccine introduction in a low income country. Both costs of resources required to introduce the vaccine (or initial one-time investment, such as cold chain equipment purchases) and recurrent (ongoing costs that repeat every year) costs, such as transport and health personnel time, were analyzed. The cost per dose, cost per fully immunized girl (FIG) and cost per eligible girl were compared across studies. Costs varied among pilot projects and estimates of national programs due to differences in scale and service delivery strategy. The average introduction costs per fully immunized girl ranged from $1.49 to $18.94 while recurrent costs per girl ranged from $1.00 to $15.69, with both types of costs varying by delivery strategy and country. Evaluating delivery costs along programme characteristics as well as country characteristics (population density, income/cost level, existing service delivery infrastructure) are likely the most informative and useful for anticipating costs

  17. Evaluation of policies and practices to prevent mother to child transmission of hepatitis B virus in China: results from China GAVI project final evaluation.

    PubMed

    Cui, Fuqiang; Luo, Huiming; Wang, Fuzhen; Zheng, Hui; Gong, Xiaohong; Chen, Yuansheng; Wu, Zhenhua; Miao, Ning; Kane, Mark; Hennessey, Karen; Hadler, Stephen C; Hutin, Yvan J; Liang, Xiaofeng; Yang, Weizhong

    2013-12-27

    Mother to Child Transmission (MTCT) has remained a leading cause of HBV infection in China, accounting for 40% of total infections. Providing hepatitis B vaccine (HepB) to all infants within 24h of birth (Timely Birth Dose, TBD), and subsequent completion of at least 3 vaccine doses is key to preventing perinatal HBV infection. In 2002, with the financial support of the Global Alliance on Vaccine and Immunization (GAVI) targeted to Western region and 223 poverty-affected counties in Central region, hepatitis B vaccine was provided for free. In 2010, we evaluated the China GAVI project in terms of its activities to prevent perinatal infections. The objectives of the evaluation were to (1) measure achievements in the China GAVI project in terms of TBD coverage, and (2) describe practices for HBsAg screening of pregnant women and HBIG use outside the GAVI China project. We used the methods recommended by WHO to select a cluster sample of health care facilities for the purpose of an injection safety assessment. We stratified China into three regions based on economic criteria, and selected eight counties with a probability proportional to population size in each region. In each selected county, we selected (a) 10 townships at random among the list of townships of the county and (b) the one county level hospital. In each hospital, we abstracted 2002 through 2009 records to collect information regarding birth cohorts, hospitals deliveries, vaccine management, hepatitis B vaccination delivery, HBsAg screening practices and results, and HBIG administration. In addition, in all hospitals, we abstracted records regarding the delivery of TBD. We visited 244 facilities in the three regions, including 24 county hospitals and 220 township hospitals. We reviewed 837,409 birth summary records, 699,249 for infants born at county or township hospitals. Hospital delivery rates increased from 58% in 2002 to 93% in 2009. Surveyed TBD coverage increased from 60% in 2002 to 91% in 2009

  18. 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

  19. 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.

  20. What have we learned on costs and financing of routine immunization from the comprehensive multi-year plans in GAVI eligible countries?

    PubMed

    Brenzel, Logan

    2015-05-07

    Immunization is one of the most cost-effective health interventions, but as countries introduce new vaccines and scale-up immunization coverage, costs will likely increase. This paper updates estimates of immunization costs and financing based on information from comprehensive multi-year plans (cMYPs) from GAVI-eligible countries during a period when countries planned to introduce a range of new vaccines (2008-2016). The analysis database included information from baseline and 5-year projection years for each country cMYP, resulting in a total sample size of 243 observations. Two-thirds were from African countries. Cost data included personnel, vaccine, injection, transport, training, maintenance, cold chain and other capital investments. Financing from government and external sources was evaluated. All estimates were converted to 2010 US Dollars. Statistical analysis was performed using STATA, and results were population-weighted. Results pertain to country planning estimates. Average annual routine immunization cost was $62 million. Vaccines continued to be the major cost driver (51%) followed by immunization-specific personnel costs (22%). Non-vaccine delivery costs accounted for almost half of routine program costs (44%). Routine delivery cost per dose averaged $0.61 and the delivery cost per infant was $10. The cost per DTP3 vaccinated child was $27. Routine program costs increased with each new vaccine introduced. Costs accounted for 5% of government health expenditures. Governments accounted for 67% of financing. Total and average costs of routine immunization programs are rising as coverage rates increase and new vaccines are introduced. The cost of delivering vaccines is nearly equivalent to the cost of vaccines. Governments are financing greater proportions of the immunization program but there may be limits in resource scarce countries. Price reductions for new vaccines will help reduce costs and the burden of financing. Strategies to improve efficiency

  1. Ba incorporation in benthic foraminifera

    NASA Astrophysics Data System (ADS)

    de Nooijer, Lennart J.; Brombacher, Anieke; Mewes, Antje; Langer, Gerald; Nehrke, Gernot; Bijma, Jelle; Reichart, Gert-Jan

    2017-07-01

    Barium (Ba) incorporated in the calcite of many foraminiferal species is proportional to the concentration of Ba in seawater. Since the open ocean concentration of Ba closely follows seawater alkalinity, foraminiferal Ba / Ca can be used to reconstruct the latter. Alternatively, Ba / Ca from foraminiferal shells can also be used to reconstruct salinity in coastal settings in which seawater Ba concentration corresponds to salinity as rivers contain much more Ba than seawater. Incorporation of a number of minor and trace elements is known to vary (greatly) between foraminiferal species, and application of element / Ca ratios thus requires the use of species-specific calibrations. Here we show that calcite Ba / Ca correlates positively and linearly with seawater Ba / Ca in cultured specimens of two species of benthic foraminifera: Heterostegina depressa and Amphistegina lessonii. The slopes of the regression, however, vary two- to threefold between these two species (0.33 and 0.78, respectively). This difference in Ba partitioning resembles the difference in partitioning of other elements (Mg, Sr, B, Li and Na) in these foraminiferal taxa. A general trend across element partitioning for different species is described, which may help develop new applications of trace elements in foraminiferal calcite in reconstructing past seawater chemistry.

  2. 3.30 Ga high-silica intraplate volcanic-plutonic system of the Gavião Block, São Francisco Craton, Brazil: Evidence of an intracontinental rift following the creation of insulating continental crust

    NASA Astrophysics Data System (ADS)

    Zincone, Stefano A.; Oliveira, Elson P.; Laurent, Oscar; Zhang, Hong; Zhai, Mingguo

    2016-12-01

    High-silica rhyolites having U-Pb zircon ages of 3303 ± 11 Ma occur along the eastern border of the Gavião Block (Brazil) associated with the Contendas-Mirante and Mundo Novo supracrustal belts. Unlike many Archean greenstone sequences, they are not interlayered with mafic to intermediate units. Instead, they belong to an inter-related plutonic-volcanic system, together with granitic massifs having similar zircon crystallization ages of ca. 3293 ± 3 Ma and 3328 ± 3 Ma and plotting along the same geochemical trends as the rhyolites. The rhyolites show well-preserved primary volcanic features such as magma flow textures and euhedral phenocrysts. High emplacement temperatures are indicated by petrographic evidence (β-quartz phenocrysts), zircon saturation temperatures (915-820 °C) and geochemical data, especially high SiO2 (74-79 wt.%) together with elevated Fe2O3(T) ( 3 wt.%), MgO (0.5-1.5 wt.%) and low Al2O3 (< 11 wt.%). The rhyolites show homogeneous trace element ratios (La/YbN 4.8 ± 1.8; EuN/Eu* 0.55; Sr/Y 0.7) and negative ԐHf(3.3 Ga) from 0 to - 7, indicating derivation from a single crustal source for both occurrences. Specifically, the rhyolites would have derived from extraction and eruption of highly silicic residual liquid formed by crystallization of granitic magma in a relatively shallow (< 10 km) reservoir, now represented by the granite massifs. The granite magma was formed by melting or differentiation of material similar to the diorite gneiss that occurs regionally. The 3.30 Ga volcanic-plutonic systems formed after a period of crustal growth and stabilization of a thick continental lithosphere, represented by massive 3.40-3.33 Ga TTG and medium to high-K calk-alkaline magmatism in the Gavião Block. The 3.30 Ga-old rhyolites and granites would therefore have formed in an intracontinental tectonic setting after the formation and stabilization of new continental crust, and accordingly would represent the first stages of rifting and continental

  3. 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.

  4. 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.

  5. Who pays for cooperation in global health? A comparative analysis of WHO, the World Bank, the Global Fund to Fight HIV/AIDS, Tuberculosis and Malaria, and Gavi, the Vaccine Alliance.

    PubMed

    Clinton, Chelsea; Sridhar, Devi

    2017-01-27

    In this report we assess who pays for cooperation in global health through an analysis of the financial flows of WHO, the World Bank, the Global Fund to Fight HIV/AIDS, TB and Malaria, and Gavi, the Vaccine Alliance. The past few decades have seen the consolidation of influence in the disproportionate roles the USA, UK, and the Bill & Melinda Gates Foundation have had in financing three of these four institutions. Current financing flows in all four case study institutions allow donors to finance and deliver assistance in ways that they can more closely control and monitor at every stage. We highlight three major trends in global health governance more broadly that relate to this development: towards more discretionary funding and away from core or longer-term funding; towards defined multi-stakeholder governance and away from traditional government-centred representation and decision-making; and towards narrower mandates or problem-focused vertical initiatives and away from broader systemic goals.

  6. 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%.

  7. Event Structure and the "Ba" Construction.

    ERIC Educational Resources Information Center

    Rhys, Catrin Sian

    1996-01-01

    Much earlier controversy surrounding the Chinese "ba" construction stems from dissention over whether or not "ba" has any independent semantic content. "Ba" was assumed either to be a purely formal particle whose function was to assign case, or to have semantic content translating into thematic content. However, under the hypothesis that abstract…

  8. Y-Ba Superconducting Ceramics

    NASA Astrophysics Data System (ADS)

    Shunbao, Tian; Xiaofei, Li; Tinglian, Wen; Zuxiang, Lin; Shichun, Li; Huijun, Yu

    Polycrystalline Y-Ba-Cu-O superconducting materials have been studied. It was found that chemical composition and processing condition may play an important role in the final structure and superconducting properties. The density has been determined and compared with the calculated value according to the structure model reported by Bell Labs. The grain size and the morphology of the materials were observed by SEM.

  9. 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.

  10. IBFM for Ba isotopes and chaoticity

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Cáta-Danil, G.; Ivasçu, M.; Gizon, A.; Gizon, J.; Ur, C. A.

    1992-06-01

    Fluctuation properties have been analysed for the energy levels predicted by IBFM calculations in the Ba isotopes121Ba to131Ba. The results indicate, in general, a situation which is close to the chaotic limit. For the lighter isotopes studied (121 and 123), a phase transition is obtained in the low-spin, positive parity states, from a situation close to regularity at low excitation energies, towards chaoticity at higher excitations.

  11. Ba2phenanthrene is the main component in the Ba-doped phenanthrene superconductor

    NASA Astrophysics Data System (ADS)

    Yan, Xun-Wang; Huang, Zhongbing; Lin, Hai-Qing

    2014-12-01

    We have systematically investigated the crystal structure of Ba-doped phenanthrene with various Ba doping levels by the first-principles calculations combined with the X-ray diffraction (XRD) spectra simulations. Although the experimental stoichiometry ratio of Ba atom and phenanthrene molecule is 1.5:1, the simulated XRD spectra, space group symmetry and optimized lattice parameters of Ba1.5phenanthrene are not consistent with the experimental ones, while the results for Ba2phenanthrene are in good agreement with the measurements. The strength difference of a few XRD peaks can be explained by the existence of pristine phenanthrene. Our findings suggest that instead of uniform Ba1.5phenanthrene, there coexist Ba2phenanthrene and undoped phenanthrene in the superconducting sample. The electronic calculations indicate that Ba2phenanthrene is a semiconductor with a small energy gap less than 0.05 eV.

  12. Ba{sub 2}phenanthrene is the main component in the Ba-doped phenanthrene superconductor

    SciTech Connect

    Yan, Xun-Wang; Huang, Zhongbing; Lin, Hai-Qing

    2014-12-14

    We have systematically investigated the crystal structure of Ba-doped phenanthrene with various Ba doping levels by the first-principles calculations combined with the X-ray diffraction (XRD) spectra simulations. Although the experimental stoichiometry ratio of Ba atom and phenanthrene molecule is 1.5:1, the simulated XRD spectra, space group symmetry and optimized lattice parameters of Ba{sub 1.5}phenanthrene are not consistent with the experimental ones, while the results for Ba{sub 2}phenanthrene are in good agreement with the measurements. The strength difference of a few XRD peaks can be explained by the existence of pristine phenanthrene. Our findings suggest that instead of uniform Ba{sub 1.5}phenanthrene, there coexist Ba{sub 2}phenanthrene and undoped phenanthrene in the superconducting sample. The electronic calculations indicate that Ba{sub 2}phenanthrene is a semiconductor with a small energy gap less than 0.05 eV.

  13. Quasi-classical Trajectory Study of Ba+HI→BaI+H Reaction

    NASA Astrophysics Data System (ADS)

    Atasie, V. N.

    2010-10-01

    The quasi-classical trajectory calculations based on extended London-Eyring-Polanyi-Sato potential energy surface have been used to study the reaction of Ba+HI→BaI+H system. The rotational, vibrational, translational, and angular distributions of the product BaI have been calculated. The calculated results are in good agreement with the experimental ones.

  14. BaGe6 and BaGe(6-x): incommensurately ordered vacancies as electron traps.

    PubMed

    Akselrud, Lev; Wosylus, Aron; Castillo, Rodrigo; Aydemir, Umut; Prots, Yurii; Schnelle, Walter; Grin, Yuri; Schwarz, Ulrich

    2014-12-15

    We report the high-pressure high-temperature synthesis of the germanium-based framework compounds BaGe6 (P = 15 GPa, T = 1073 K) and BaGe(6-x) (P = 10 GPa, T = 1073 K) which are metastable at ambient conditions. In BaGe(6-x), partial fragmentation of the BaGe6 network involves incommensurate modulations of both atomic positions and site occupancy. Bonding analysis in direct space reveals that the defect formation in BaGe(6-x) is associated with the establishment of free electron pairs around the defects. In accordance with the electron precise composition of BaGe(6-x) for x = 0.5, physical measurements evidence semiconducting electron transport properties which are combined with low thermal conductivity.

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

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

    The dielectric response to an inhomogeneous electric field has been investigated for Ba and Ba2 within a molecular beam experiment. The ratio of the polarizabilities per atom of Ba2 and Ba is determined to be 1.30±0.13 . The experimental result is compared to a high level ab initio quantum chemical coupled cluster calculation with an energy-consistent scalar relativistic small-core pseudopotential for Ba. For the barium atom a polarizability of 40.82Å3 is obtained and the isotropic value of the polarizability calculated for Ba2 is 97.88Å3 , which is in good agreement with the experimental results, demonstrating that a quantitative understanding of the interaction between two closed-shell heavy element metal atoms has been achieved.

  16. The BaBar electromagnetic calorimeter

    SciTech Connect

    Stahl, A.

    1997-07-01

    The progress on the design and construction of the BaBar electromagnetic calorimeter including its mechanical structure, the readout system, the mechanical and optical properties of the crystals, and the schedule for the final assembly and testing is summarized.

  17. Thermophysical properties of BaUO4

    NASA Astrophysics Data System (ADS)

    Tanaka, Kosuke; Tokushima, Kazuyuki; Kurosaki, Ken; Ohishi, Yuji; Muta, Hiroaki; Yamanaka, Shinsuke

    2013-11-01

    Polycrystalline specimens of barium uranate, BaUO4, were prepared and several properties such as the thermal expansion coefficient, elastic moduli, thermal conductivity, and Debye temperature were evaluated. The sintered specimens had a single-phase orthorhombic structure and were crack-free. The elastic moduli of BaUO4 were determined from the longitudinal and shear sound velocities and from micro-indentation tests. The Debye temperature was also determined from the sound velocities and lattice parameter measurements. The thermal conductivity of BaUO4 was calculated from the measured density at room temperature, literature values of heat capacity, and thermal diffusivity measured by the laser flash method in vacuum. The thermophysical properties of BaUO4 were examined and compared with literature data for other barium ternary oxides and SrUO4.

  18. BaBar Forward Endcap Upgrade

    SciTech Connect

    Anulli, F.

    2004-06-17

    The muon and neutral hadron detector (Instrumented Flux Return or IFR) in the forward endcap of the BaBar detector at SLAC was upgraded by the installation of a new generation of Resistive Plate Chambers (RPCs) and by increasing the absorber. The chamber replacement was made necessary by the rapid aging and efficiency loss of the original BaBar RPCs. Based on our experience with those original RPCs and 24 RPCs with thinner linseed oil treatments, improvements in the design, construction, and testing of the new generation RPCs were implemented and are described in detail.

  19. BaBar forward endcap upgrade

    NASA Astrophysics Data System (ADS)

    Anulli, F.; Baldini, R.; Calcaterra, A.; Daniello, L.; de Sangro, R.; Finocchiaro, G.; Patteri, P.; Piccolo, M.; Santoni, M.; Zallo, A.; Cheng, C. H.; Lange, D. J.; Wright, D. M.; Boyce, R.; Krebs, J.; Messner, R.; Putallaz, G.; Wisniewski, W. J.; Buzzo, A.; Crosetti, G.; LoVetere, M.; Minutoli, S.; Passaggio, S.; Pollovio, P.; Robutti, E.; Tosi, S.; Trovato, A.; Cartaro, C.; Fabozzi, F.; Lista, L.; Piccolo, D.; Paolucci, P.; Avanzini, C.; Carpinelli, M.; Forti, F.; Neri, N.; Paoloni, E.; Rizzi, D.; Bellini, F.; Buccheri, A.; Cavoto, G.; del Re, D.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gargiulo, C.; Gaspero, M.; Lunadei, R.; Mazzoni, M. A.; Morganti, S.; Pelosi, A.; Pierini, M.; Piredda, G.; Voena, C.; Sinev, N.; Strom, D.; Foulkes, S.; Wang, K.; Band, H. R.; Hollar, J.; Tan, P.

    2005-02-01

    The muon and neutral hadron detector (instrumented flux return or IFR) in the forward endcap of the BaBar detector at SLAC was upgraded by the installation of a new generation of resistive plate chambers (RPCs) and by increasing the absorber. The chamber replacement was made necessary by the rapid aging and efficiency loss of the original BaBar RPCs. Based on our experience with those original RPCs and 24 RPCs with thinner linseed oil treatments, improvements in the design, construction, and testing of the new generation RPCs were implemented and are described in detail.

  20. Liquidus temperatures and phase equilibria in the BaCl2-MCl-BaO systems

    NASA Astrophysics Data System (ADS)

    Nikolaeva, E. V.; Bovet, A. L.; Korzun, I. V.

    2017-02-01

    The liquidus temperatures of the BaO-BaCl2-MCl systems (with M = alkali metal) are determined by thermal analysis. The caloric effects observed during melting of the barium-containing chloride eutectic with barium oxide additions are studied. A chemical mechanism of barium oxide dissolution in the melts is confirmed. X-ray diffraction patterns taken for the melt solidified after experiment indicate the presence of barium oxychloride Ba4OCl6 in the solid phase. It is shown that the significant increase in the liquidus temperature in adding the barium oxide to barium-containing chloride molten mixtures is related to substantial changes in their composition and structure.

  1. Subnitride chemistry: A first-principles study of the NaBa 3N, Na 5Ba 3N, and Na 16Ba 6N phases

    NASA Astrophysics Data System (ADS)

    Oliva, Josep M.

    2005-04-01

    An ab initio study on the electronic structure of the subnitrides NaBa 3N, Na 5Ba 3N, and Na 16Ba 6N is performed for the first time. The NaBa 3N and Na 5Ba 3N phases consist of infinite 1∞[NBa 6/2] strands composed of face-sharing NBa 6 octahedra surrounded by a "sea" of sodium atoms. The Na 16Ba 6N phase consist of discrete [NBa 6] octahedra arranged in a body-cubic fashion, surrounded by a "sea" of sodium atoms. Our calculations suggest that the title subnitrides are metals. Analysis of the electronic structure shows partial interaction of N(2s) with Ba(5 p) electrons in the lower energy region for NaBa 3N and Na 5Ba 3N. However, no dispersion is observed for the N(2s) and Ba(5 p) bands in the cubic phase Na 16Ba 6N. The metallic band below the Fermi level shows a strong mixing of N(2p), Ba(6 s), Ba(5 d), Ba(6 p), Na(3 s) and Na(3 p) orbitals. The metallic character in these nitrides stems from delocalized electrons corresponding to hybridized 5dl6sm6pn barium orbitals which interact with hybridized 3sn3pm sodium orbitals. Analysis of the electron density and electronic structure in these nitrides shows two different regions: a metallic matrix corresponding to the sodium atoms and the regions around them and heteropolar bonding between nitrogen and barium within the infinite 1∞[NBa 6/2] strands of the NaBa 3N and Na 5Ba 3N phases, and within the isolated [NBa 6] octahedra of the Na 16Ba 6N phase. The nitrogen atoms inside the strands and octahedra are negatively charged, the anionic character of nitrogens being larger in the isolated octahedra of the cubic phase Na 16Ba 6N, due to the lack of electron delocalization along one direction as opposed to the other phases. The sodium and barium atoms appear to be slightly negatively and positively charged, the latter to a larger extent. From the computed Ba-N overlap populations as well as the analysis of the contour maps of differences between total density and superposition of atomic densities, we suggest

  2. 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.

  3. 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.

  4. 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

  5. Charm Physics at BaBar

    SciTech Connect

    Chen, Chunhui; /Maryland U.

    2005-06-29

    Large production of the c{bar c} pairs and high integrated luminosity make the PEPII B Factory an excellent place for studying the charm hadrons. In this paper, we present a few most recent results from BaBar collaboration in charm sector.

  6. Semileptonic B decays at BaBar

    SciTech Connect

    Cote, D.; /Montreal U.

    2007-05-23

    This paper summarizes the content of a talk given by the author at the Lake Louise Winter Institute, on February 21st 2007. It presents recent measurements of the rates for semileptonic B decays using data collected by the BaBar detector at the PEP-II asymmetric-energy collider at the Stanford Linear Accelerator Center.

  7. Magnetic comparison of BaCa and BaSr substituted hexaferrite powders

    NASA Astrophysics Data System (ADS)

    González-Angeles, A.; Lipka, J.; Grusková, A.; Sláma, J.; Jančárik, V.; Slugeň, V.

    2010-03-01

    Results on magnetic studies of Ba0.5Sr0.5Fe12-2x(ZnTi)xO19 and Ba0.75Ca0.25Fe12-2x(ZnTi)xO19, where x = 0.2 to 0.6, ferromagnetic powders prepared by mechanical alloying are discussed. The structural and magnetic properties of the resulting powders were analyzed by thermo-magnetic analysis, X-ray diffraction, scanning electron microscopy, Mössbauer spectroscopy and magnetic measurements. Curie temperature, Tc decreased dramatically (drop ~ 39%) for BaCa samples, whilst for BaSr samples remained almost without change (diminution ~ 2%) at x <= 0.2. SEM studies showed that all the particles present nearly hexagonal platelet shape.

  8. Spectroscopy of Ba and Ba+ deposits in solid xenon for barium tagging in nEXO

    NASA Astrophysics Data System (ADS)

    Mong, B.; Cook, S.; Walton, T.; Chambers, C.; Craycraft, A.; Benitez-Medina, C.; Hall, K.; Fairbank, W.; Albert, J. B.; Auty, D. J.; Barbeau, P. S.; Basque, V.; Beck, D.; Breidenbach, M.; Brunner, T.; Cao, G. F.; Cleveland, B.; Coon, M.; Daniels, T.; Daugherty, S. J.; DeVoe, R.; Didberidze, T.; Dilling, J.; Dolinski, M. J.; Dunford, M.; Fabris, L.; Farine, J.; Feldmeier, W.; Fierlinger, P.; Fudenberg, D.; Giroux, G.; Gornea, R.; Graham, K.; Gratta, G.; Heffner, M.; Hughes, M.; Jiang, X. S.; Johnson, T. N.; Johnston, S.; Karelin, A.; Kaufman, L. J.; Killick, R.; Koffas, T.; Kravitz, S.; Krücken, R.; Kuchenkov, A.; Kumar, K. S.; Leonard, D. S.; Licciardi, C.; Lin, Y. H.; Ling, J.; MacLellan, R.; Marino, M. G.; Moore, D.; Odian, A.; Ostrovskiy, I.; Piepke, A.; Pocar, A.; Retiere, F.; Rowson, P. C.; Rozo, M. P.; Schubert, A.; Sinclair, D.; Smith, E.; Stekhanov, V.; Tarka, M.; Tolba, T.; Twelker, K.; Vuilleumier, J.-L.; Walton, J.; Weber, M.; Wen, L. J.; Wichoski, U.; Yang, L.; Yen, Y.-R.; Zhao, Y. B.; nEXO Collaboration

    2015-02-01

    Progress on a method of barium tagging for the nEXO double beta decay experiment is reported. Absorption and emission spectra for deposits of barium atoms and ions in solid xenon matrices are presented. Excitation spectra for prominent emission lines, temperature dependence, and bleaching of the fluorescence reveal the existence of different matrix sites. A regular series of sharp lines observed in Ba+ deposits is identified with some type of barium hydride molecule. Lower limits for the fluorescence quantum efficiency of the principal Ba emission transition are reported. Under current conditions, an image of fewer than or equal to 104 Ba atoms can be obtained. Prospects for imaging single Ba atoms in solid xenon are discussed.

  9. 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

  10. Geometry and Unoccupied Electronic States of Ba and BaO on W(001)

    NASA Technical Reports Server (NTRS)

    Lamouri, A.; Mueller, W.; Krainsky, I. L.

    1994-01-01

    A study aimed at understanding the geometrical and electronic properties of barium and oxygen coadsorbed on the tungsten(001) surface has been carried out by means of work-function measurements (Delta-phi), Auger-electron spectroscopy, low-energy electron diffraction, inverse photoelectron spectroscopy, and relativistic-electronic-structure calculations. A report of the experimental measurements and a comparison with theoretical results from embedded-cluster-model calculations are presented. Our experimental studies show that the work function of the W(001) surface (phi = 4.63 eV) is lowered to approximately 2.3-2.4 eV by coadsorption of 1 ML of Ba and O regardless of the order of deposition of these two species. The technique of IPS in the isochromat mode was used to determine the unoccupied electronic-energy band structure for ordered c (2 X 2) Ba and O layers on W(001). Several spectral features are observed above the Fermi level (E(F)), which we assign to transitions into Ba and W d-states. The measured two-dimensional electronic band structure is independent of the order of Ba and O deposition. Using embedded-cluster-model calculations, we investigated two possible adsorption configurations of an ordered c(2 X 2) adlayer of Ba and O on W(001): 'tilted,' where Ba and O are placed on alternate fourfold-hollow sites, and 'upright,' where the adsorbed atoms lay above the same site with Ba outer-most. The calculated densities of states for the tilted geometry show distinct peaks above E(F) originating from Ba and W d-orbitals and are in good agreement with the experimental results.

  11. 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.

  12. Dynamics of photoexcited Ba(+) cations in (4)He nanodroplets.

    PubMed

    Leal, Antonio; Zhang, Xiaohang; Barranco, Manuel; Cargnoni, Fausto; Hernando, Alberto; Mateo, David; Mella, Massimo; Drabbels, Marcel; Pi, Martí

    2016-03-07

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

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

    NASA Astrophysics Data System (ADS)

    Leal, Antonio; Zhang, Xiaohang; Barranco, Manuel; Cargnoni, Fausto; Hernando, Alberto; Mateo, David; Mella, Massimo; Drabbels, Marcel; Pi, Martí

    2016-03-01

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

  14. Ba and BaO on W and on Sc 2O 3 coated W

    NASA Astrophysics Data System (ADS)

    Shih, A.; Yater, J. E.; Hor, C.

    2005-03-01

    Temperature-programmed desorption (TPD) and Auger electron spectroscopy (AES) are used to characterize the surface layers that form under an evaporating flux of a dispenser cathode (which is a Ba and BaO source) on a W substrate and Sc 2O 3-coated W substrate to simulate the surface layer of a conventional dispenser cathode and scandate cathode, respectively. The surface layers were prepared while the substrate was either at 940 °C b (1272 K), a typical operating temperature, or at 1125 °C b (1477 K), a typical activation temperature. Our investigation found that a partial layer of BaO formed on W, similar to the surface layer that forms on a dispenser cathode. Heating to the activation temperature causes the BaO to form a stronger bond with W. For the Sc 2O 3-coated W substrate, heating to the activation temperature is necessary for the inter-diffusion between the Sc 2O 3 and W to occur. BaO layers form a stronger bond to the inter-diffused layer than to pure W. However, the most important finding is that a stable BaO-containing compound forms and continues to accumulate under the impinging flux on the Sc 2O 3 and W covered substrate at 940 °C b. Surface emission models describe successfully all other dispenser cathodes, but fail to explain the emission characteristics of scandate cathodes. Raju and Maloney proposed an alternate model, which requires the presence of a thick layer of semi-conducting material. Our finding suggests that it is possible to form a thick layer from simultaneous presence of BaO, Sc 2O 3 and W. However, further investigation is necessary to determine if the Raju and Maloney type layer is indeed present on top of scandate cathodes.

  15. 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.; ...

    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

  16. 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.

  17. Synthesis and crystal structure of LiBa 2N and identification of LiBa 3N

    NASA Astrophysics Data System (ADS)

    Smetana, Volodymyr; Babizhetskyy, Volodymyr; Vajenine, Grigori V.; Simon, Arndt

    2007-06-01

    The metal-rich part of the Li sbnd Ba sbnd N system was investigated using powder and single-crystal X-ray diffraction analysis. The crystal structures of two new ternary subnitrides, LiBa 2N and of LiBa 3N, were determined from single-crystal and powder X-ray diffraction data, respectively. LiBa 2N has a tetragonal structure (space group, P4 2/nmc, Z=8, a=7.980(1), c=14.263(2) Å). The structure contains infinite mutually perpendicular rows of edge-sharing LiBa 5N octahedra. LiBa 3N is isostructural with NaBa 3N ( P6 3/mmc, Z=2, a=8.182(1), c=6.922(4) Å).

  18. 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}.

  19. New Spectroscopy at BaBar

    SciTech Connect

    Mazzoni, M.A.; /INFN, Rome

    2007-04-18

    The Babar experiment at the SLAC B factory has accumulated a high luminosity that offers the possibility of systematic studies of quarkonium spectroscopy and of investigating rare new phenomena. Recent results in this field are presented. In recent times spectroscopy has become exciting again, after the discovery of new states that are not easily explained by conventional models. States such as the X(3872) and the Y(4260) could be new excited charmonium states, but require precise measurements for positive identification. The BaBar experiment [1] is installed at the asymmetric storage ring PEP-II. 90% of the data accumulated by BaBar are taken at the Y(4S) (10.58 GeV) and 10% just below (10.54 GeV). The BaBar detector includes a 5-layer, double-sided silicon vertex tracker and a 40-layer drift chamber in a 1.5 T solenoidal magnetic field, which detect charged particles and measures their momenta and ionization energy losses. Photons, electrons, and neutral hadrons are detected with a CsI(Tl)-crystal electromagnetic calorimeter. An internally reflecting ring-imaging Cherenkov is also used for particle id. Penetrating muon and neutral hadrons are identified by an array of resistive-plate chambers embedded in the steel of the flux return. The detector allows good track and vertex resolution, good particle id and good photon detection so it is especially suited for spectroscopy studies.

  20. 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.

  1. Electronic correlations in vanadium chalcogenides: BaV Se(3) versus BaV S(3).

    PubMed

    Grieger, Daniel; Boehnke, Lewin; Lechermann, Frank

    2010-07-14

    Albeit structurally and electronically very similar, at low temperature the quasi-one-dimensional vanadium sulfide BaV S(3) shows a metal-to-insulator transition via the appearance of a charge-density-wave state, while BaV Se(3) apparently remains metallic down to zero temperature. This different behavior upon cooling is studied by means of density functional theory and its combination with the dynamical mean-field theory and the rotationally invariant slave-boson method. We reveal several subtle differences between these chalcogenides that provide indications for the deviant behavior of BaV Se(3) at low temperature. In this regard, a smaller Hubbard U in line with an increased relevance of the Hund's exchange J plays a vital role.

  2. Electronic correlations in vanadium chalcogenides: BaV Se3 versus BaV S3

    NASA Astrophysics Data System (ADS)

    Grieger, Daniel; Boehnke, Lewin; Lechermann, Frank

    2010-07-01

    Albeit structurally and electronically very similar, at low temperature the quasi-one-dimensional vanadium sulfide BaV S3 shows a metal-to-insulator transition via the appearance of a charge-density-wave state, while BaV Se3 apparently remains metallic down to zero temperature. This different behavior upon cooling is studied by means of density functional theory and its combination with the dynamical mean-field theory and the rotationally invariant slave-boson method. We reveal several subtle differences between these chalcogenides that provide indications for the deviant behavior of BaV Se3 at low temperature. In this regard, a smaller Hubbard U in line with an increased relevance of the Hund's exchange J plays a vital role.

  3. Atomic absorption background of Ba in EXAFS analysis of BaFe(12)O(19) nanoparticles.

    PubMed

    Padeznik Gomilšek, Jana; Kodre, Alojz; Arčon, Iztok; de Panfilis, Simone; Makovec, Darko

    2011-07-01

    The approximate barium X-ray atomic absorption in the energy region of L-edges is reconstructed from the absorption spectrum of an aqueous solution of BaCl(2). The result is corroborated by comparison with pure atomic absorption spectra of neighbour elements Xe and Cs. The application of the atomic absorption signal as a proper EXAFS background is demonstrated and discussed in the analysis of Ba hexaferrite nanoparticles with a very weak structural signal. The essential gain is found in the decrease of uncertainty intervals of structural parameters and their correlations. A simple analytical model of the absorption background for the practical EXAFS analysis is demonstrated.

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

    SciTech Connect

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

    2012-07-01

    M-type hexaferrites with compositions BaFe{sub 12}O{sub 19} (BFO), SrFe{sub 12}O{sub 19} (SFO), Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19} (BSFO), and Ba{sub 0.5}Pb{sub 0.5}Fe{sub 12}O{sub 19} (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 P6{sub 3}/mmc for BFO, SFO, and BSFO samples, whereas BPFO sample contains hematite ({alpha}-Fe{sub 2}O{sub 3}) phase with space group R3c along with the M-type main phase. All the samples show dispersion in dielectric constant ({epsilon} Prime ) and dielectric loss (tan {delta}) values with frequency. The values of {epsilon} Prime and tan {delta} 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 ({sigma}{sub ac}) and the most probable relaxation time ({tau}{sub M Double-Prime }) 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{sup *} (M Double-Prime vs M Prime ) indicate that dc conductivity dominates in the region below the M Double-Prime {sub max} point. Above M Double-Prime {sub max}, the variations follow Jonscher power law ({sigma} = A{omega}{sup s}) implying that ac conductivity is dominating in this region. Among the prepared samples, SFO hexaferrite has lowest values of {sigma}{sub ac}, {epsilon} Prime , and tan {delta} making it suitable for use in microwave devices.

  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. Growth and characterization of sputtered BSTO/BaM multilayers

    NASA Astrophysics Data System (ADS)

    Srinath, S.; Frey, N. A.; Heindl, R.; Srikanth, H.; Coffey, K. R.; Dudney, N. J.

    2005-05-01

    Multilayers of Ba0.5Sr0.5TiO3 (BSTO) and BaFe12O19 (BaM), with tunable permeability and permittivity are attractive systems for radio frequency and microwave applications. We have grown multilayers of BSTO and BaM using magnetron sputtering on Al2O3 substrates. Film growth conditions such as sputtering parameters were optimized to obtain high quality multilayers. X-ray diffraction established that both BSTO and BaM were formed and cross-sectional SEM studies showed sharp interfaces between BSTO and BaM layers. Magnetization showed a large coercivity (˜2000Oe ) consistent with the hexaferrite component. The hysteresis loops also revealed the distinct influence of magnetocrystalline and shape anisotropies at different temperatures.

  7. Growth and Characterization of Sputtered BSTO/BaM Multilayers

    SciTech Connect

    Srinath, S.; Frey, N. A.; Heindl, R.; Srikanth, H.; Coffey, K. R.; Dudney, Nancy J

    2005-01-01

    Multilayers of Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BSTO) and BaFe{sub 12}O{sub 19} (BaM), with tunable permeability and permittivity are attractive systems for radio frequency and microwave applications. We have grown multilayers of BSTO and BaM using magnetron sputtering on Al{sub 2}O{sub 3} substrates. Film growth conditions such as sputtering parameters were optimized to obtain high quality multilayers. X-ray diffraction established that both BSTO and BaM were formed and cross-sectional SEM studies showed sharp interfaces between BSTO and BaM layers. Magnetization showed a large coercivity ( {approx}2000 Oe) consistent with the hexaferrite component. The hysteresis loops also revealed the distinct influence of magnetocrystalline and shape anisotropies at different temperatures.

  8. Preparation of directionally solidified BaTi2O5-Ba6Ti17O40 eutectic by the floating zone method

    NASA Astrophysics Data System (ADS)

    Shiga, K.; Katsui, H.; Goto, T.

    2017-02-01

    The BaTi2O5-Ba6Ti17O40 eutectic (BaO-68.7 mol% TiO2) was directionally solidified by the floating zone (FZ) method and crystalline phases, microstructures and orientation were investigated. Ba6Ti17O40 with faceted rod-like shape was dispersed in the BaTi2O5 matrix. The growth directions of BaTi2O5 and Ba6Ti17O40 were parallel to the b and a axis, respectively, and the orientation relations were BaTi2O5 (010)//Ba6Ti17O40(60 2 ̅) and BaTi2O5 (001)//Ba6Ti17O40 (001).

  9. 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.

  10. Polarizabilities of Ba and Ba{sub 2}: Comparison of molecular beam experiments with relativistic quantum chemistry

    SciTech Connect

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

    2007-11-15

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

  11. 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.

  12. Porous Ba Ferrite Prepared from Wood Template

    PubMed Central

    Adachi, Nobuyasu; Kuwahara, Masayuki; Sia, Chee Kiong; Ota, Toshitaka

    2009-01-01

    Ba ferrite materials with porous microstructures were prepared from a natural cedar wood template in order to investigate new electromagnetic shielding materials. The wood templates were infiltrated with barium nitrate and iron nitrate solutions (molar ratio = 1:12) and dried to form ferrite gel, then, they were sintered in air at a temperature between 800 °C and 1400 °C. The 1-dimensional porous structures were retained after sintering and the pore size was approximately 10–20 μm. These ferrites show large coercive force and anisotropy field. The largest coercive force was obtained for the specimen sintered at 800 °C.

  13. 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.

  14. Syntheses, structures, and electronic properties of Ba3FeUS6 and Ba3AgUS6.

    PubMed

    Mesbah, Adel; Malliakas, Christos D; Lebègue, Sébastien; Sarjeant, Amy A; Stojko, Wojciech; Koscielski, Lukasz A; Ibers, James A

    2014-03-17

    The compounds Ba3FeUS6 and Ba3AgUS6 have been synthesized by the reactions of BaS, U, S, and M (= Fe or Ag) at 1223 K. These two isostructural compounds crystallize in the K4CdCl6 structure type in the trigonal system in space group D3d(6)–R3c. Both structures feature infinite ∞(1)[MUS6(6–)] chains along c that are separated by Ba atoms. The ∞(1)[FeUS6(6–)] chains are formed by the face-sharing of US6 trigonal prisms with FeS6 octahedra; in contrast, the ∞(1)[AgUS6(6–)] chains are formed by the face-sharing of US6 octahedra with AgS6 trigonal prisms. The Ba3FeUS6 compound charge balances with 3 Ba(2+), 1 Fe(2+), 1 U4+, and 6 S(2–), whereas Ba3AgUS6 charge balances with 3 Ba(2+), 1 Ag(1+), 1 U(5+), and 6 S(2–). This structure offers a remarkable flexibility in terms of the oxidation state of the incorporated uranium depending on the oxidation state of the d-block metal. DFT calculations performed with the HSE functional have led to band gaps of 2.3 and 2.2 eV for Ba3FeUS6 and Ba3AgUS6, respectively. From resistivity measurements, the Arrhenius activation energies are 0.12(1) and 0.43(1) eV for Ba3FeUS6 and Ba3AgUS6, respectively.

  15. Ba(OH)2 Equilibria in the System Ba-O-H-F, With Application to the Formation of Ba2YCu3O6.5 + x From BaF2-Precursors

    PubMed Central

    Cook, L. P.; Wong-Ng, W.; Feenstra, R.

    2005-01-01

    The ex situ process for fabricating Ba2YCu3O6.5 + x superconducting tapes from BaF2- based precursors involves a hydration/oxidation reaction at ≈730 °C to 750 °C generally written as: (2BaF2+Y+3Cu)(amorphous)+(2H2O+2.25O2)(g)→Ba2YCu3O6.5+x(s)+4HF(g). However, microscopic observations of partially processed films suggest the presence of a transient liquid phase during conversion. Alternatively, the conversion reaction can be rewritten as the sum of several intermediate steps, including the formation of a barium hydroxide liquid: (BaF2)(amorphous)+2H2O(g)→Ba(OH)2(liq)+2HF(g). To evaluate the possibility of a hydroxide liquid conversion step, thermodynamic calculations on the stability of Ba(OH)2(liq) have been completed from 500 °C to 900 °C at 0.1 MPa ptotal. Based on currently available data, the calculated phase diagrams suggest that a viable hydroxide reaction path exists in the higher part of this temperature range. The calculations indicate that Ba(OH)2(liq) may be stable at log pH2O (Pa) values from ≈4 to 5, provided log pHF (Pa) values can be maintained below 0 to −1. Limited experimental confirmation is provided by results of an experiment on BaF2(s) at 815 °C, 0.1 MPa pH2O, in which essentially all F at the surface was replaced by O. It is therefore possible that processing routes exist for producing Ba2YCu3O6.5 + x based on the presence of a Ba(OH)2 liquid, which might have an effect on conversion rates and texturing in the superconducting film. PMID:27308108

  16. Evolution Of The Oval Ba During 2004-2005

    NASA Astrophysics Data System (ADS)

    Go, Christopher Y.; de Pater, I.; Wong, M.; Lockwood, S.; Marcus, P.; Asay-Davis, X.; Shetty, S.

    2006-09-01

    During 1939-41, dark features appeared in the South Tropical Zone, and in between these features the 3 Great South Temperate Belt White Ovals, designated as BC, DE and FA, emerged (The Giant Planet Jupiter, J. Rogers p.223). The ovals were elongated, like the Great Red Spot (GRS), with an aspect ratio (major/minor axis) of about 2. The ovals merged in 1998-2000 into White Oval BA, and this oval was much rounder than its predecessors, with an aspect ratio of 1.3. Since 2000 the Oval has been observed regularly from the ground by amateur astronomers, using equipment that provided diffraction-limited images of Jupiter. These images reveal major changes in the Oval BA. During the last conjunction between the Oval BA and the GRS, in 2004, the Oval BA became more elongated for a brief period of time. During the 2005 apparition of Jupiter, features were observed inside the Oval BA. These changes culminated in December 2005 when the Oval BA turned red (between December 1-9), the same shade of red as the GRS. Methane band images (892nm) showed that the Oval BA, like the GRS, is bright. This filter signifies high altitude clouds. Amateur images along with Hubble Space Telescope images further showed the formation of a red ring inside Oval BA. Another conjunction between the Oval BA and the GRS is currently on going. As in 2004, the Oval BA is now more elongated. In this poster we will show a compilation of images taken between 2004 and 2006, highlighting the changes that have occurred in Oval BA throughout conjunction in July 2006. Amateur images, alongside HST observations from April 2006, and Keck adaptive optics images from 21 July 2006 (UT) will be shown.

  17. Syntheses, characterization, and optical properties of ternary Ba-Sn-S system compounds: acentric Ba7Sn5S15, centric BaSn2S5, and centric Ba6Sn7S20.

    PubMed

    Luo, Zhong-Zhen; Lin, Chen-Sheng; Cheng, Wen-Dan; Zhang, Hao; Zhang, Wei-Long; He, Zhang-Zhen

    2013-01-07

    Three new ternary Ba-Sn-S system compounds, acentric Ba(7)Sn(5)S(15), centric BaSn(2)S(5), and centric Ba(6)Sn(7)S(20) have been designed and synthesized by a conventional high-temperature solid-state reaction method using the evacuated silica tubes. The crystal structure of Ba(7)Sn(5)S(15) shows the coexistence of a SnS(4) tetrahedral and a Sn(2)S(3) trigonal bipyramid. Importantly, the larger dipole moment of the [Sn(2)S(3)](2-) trigonal bipyramid group and the polarity enhancement of the bipyramidal arrangements result in a strong SHG effect at 2.05 μm, which is 10 times of the SHG intensity of the benchmark AgGaS(2) with the particle size of 30-46 μm and twice as much as that with the particle size of 150-212 μm. Evidently, the acentric Ba(7)Sn(5)S(15) is a novel IR NLO crystal material with a wide mid-IR window and a strong SHG effect, which is the first reported among the Ba-Sn-S ternary system. Moreover, Ba(7)Sn(5)S(15) can achieve type-I phase-matching that can be used for practical applications. In the centric BaSn(2)S(5,) all Sn atoms are coordinated by five S atoms to form novel SnS(5) trigonal bipyramid polyhedrons. In the other centric Ba(6)Sn(7)S(20), there is the coexistence of the two coordination patterns with a SnS(5) trigonal bipyramid and SnS(4) tetrahedral polyhedrons, featuring a special crystal structure in the Ba-Sn-S system.

  18. Low Temperature Synthesis of BaB6 Nanometer Powders

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaohua; Min, Guanghui; Zhang, Lin; Liang, Limei; Yu, Huashun

    The reaction synthesis of barium boride (BaB6) nanoparticles under low temperature was investigated in this study. X-ray diffraction (XRD) was used to investigate the phase and the structure of BaB6. The characterization for microstructure was performed by Field Emission Scanning Electron Microscope (FESEM) with EDS, TEM, Fourier transform infrared (FTIR) spectroscopy and Raman scattering spectroscopy. It is concluded that BaB6 nanoparticles can be successfully prepared under low temperature at 500°C. XRD pattern shows that the nanoparticles are consisted of predominantly (110)-oriented BaB6 phase. The powders are polygonal-like shape with the average size of 200 nanometers. TEM identified that each nanoparticle shows perfect single crystal and cubic structure. The boron-to-barium atomic ratio of 5.24:1 was determined, less than the stoichiometric ratio of 6:1. BaB6 nanoparticles can absorb infrared spectrum at 459, 690, 993, 1329, 1619, 2449 and 3423cm-1 in the test range of 400~4000cm-1, respectively. Three peaks at 677.1, 823.5 and 1116.4cm-1 can be observed clearly from the Raman spectra of BaB6 nanoparticles at room temperature. The results showed that the electron dispersion of B6 octahedron in BaB6 is two-dimensional pancake-type without lattice distortion, which may account for the unique physical properties of BaB6 nanoparticles.

  19. 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…

  20. 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…

  1. 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.

  2. 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.

  3. Thermodynamics and existing phase of Ba-phenanthrene

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    The thermodynaqmics for intercalation of phenanthrene (PHN) with Ba, for which superconductivity has been reported, is studied in comparison with its isomer of a linear aromatic hydrocarbon of anthracene (AN). Contrary 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 (XRD) measurements. The reactions of Ba and PHN at elevated temperatures lead this system to molecular decomposition instead of intercalation, resulting in the Ba C2 carbide or amorphous carbon formation, which is clearly supported by XRD and Raman spectroscopy. The phenomena of metallicity and superconductivity in PHN intercalated with alkaline-earth metals (Ba or Sr) should be reconsidered.

  4. Fabrication of multifilamentary Y-Ba-Cu-O oxide superconductors

    NASA Astrophysics Data System (ADS)

    Sekine, H.; Inoue, K.; Maeda, H.; Numata, K.; Mori, K.

    1988-06-01

    Workability of Y-Ba-Cu-O composite wires with an Ag sheath has been studied, and multifilamentary Y-Ba-Cu-O superconductors with an Ag matrix have been successfully fabricated. Observations of the wires with a scanning electron microscope reveal that as the areal reduction ratio R increases, the average Y-Ba-Cu-O grain size decreases. The study on the workability of the composite wires reveals that composite wires consisting of the Y-Ba-Cu-O powder and an Ag matrix can be rolled or drawn to any extent by a cold-work process with intermediate annealings at 150 C for R of about 10. Based on this study, a 252 filament Y-Ba-Cu-O wire which shows a Tc (onset) of about 95 K has been successfully fabricated.

  5. The van der Waals potentials of MgCa, MgSr, MgBa, CaSr, CaBa, and SrBa

    NASA Astrophysics Data System (ADS)

    Wei, L. M.; Li, P.; Tang, K. T.

    2015-08-01

    Based on the facts that the potential energy curves of the homo-nuclear group 2 dimers (group IIA metal), except Be2, are conformal, and they can be described by the Tang-Toennies potential model, a set of simple combining rules are proposed for the parameters of the reduced potentials of the hetero-nuclear dimers. Together with the well-established combining rules of the range parameters of the exponential repulsion and the known dispersion coefficients, these rules enable us to determine the ground state potential energy curves of MgCa, MgSr, MgBa, CaSr, CaBa, and SrBa from those of Mg2, Ca2, Sr2, and Ba2. The determined potentials are comparable to some ab initio calculations and in excellent agreement with the experiment.

  6. Vibrational properties of the gallium monohydrides SrGaGeH, BaGaSiH, BaGaGeH, and BaGaSnH

    SciTech Connect

    Evans, Michael J.; Lee, Myeong H.; Holland, Gregory P.; Daemen, Luke L.; Sankey, Otto F.; Haeussermann, Ulrich

    2009-08-15

    Vibrational properties of the gallium monohydrides SrGaGeH, BaGaSiH, BaGaGeH, and BaGaSnH (AeGaTtH) have been investigated by means of inelastic neutron scattering (INS) and first principles calculations. The compounds contain separated Ga-H units being part of a two dimensional polyanionic layer, [TtGaH]{sup 2-} (Tt=Si, Ge, Sn). The INS spectra show internal Ga-H bending and stretching modes at frequencies around 900 and 1200 cm{sup -1}, respectively. While the stretching mode is virtually invariant with respect to the variable chemical environment of the Ga-H unit, the bending mode frequency varies and is highest for BaGaSiH and lowest for BaGaSnH. The stretching mode is a direct measure of the Ga-H bond strength, whereas the bending mode reflects indirectly the strength of alkaline earth metal-hydrogen interaction. Accordingly, the terminal Ga-H bond in solid state AeGaTtH is distinct, but-compared to molecular gallium hydrides-very weak. - Graphical abstract: Vibrational properties of the gallium monohydrides SrGaGeH, BaGaSiH, BaGaGeH, and BaGaSnH have been investigated and revealed Ga-H stretching mode frequencies around 1200 cm{sup -1}. This implies that the terminal Ga-H bond in solid state polyanionic gallium hydrides is very weak compared to molecular gallium hydride species.

  7. 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.

  8. 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.

  9. When one becomes two: Ba12In4Se20, not quite isostructural to Ba12In4S19

    NASA Astrophysics Data System (ADS)

    Yin, Wenlong; Iyer, Abishek K.; Li, Chao; Yao, Jiyong; Mar, Arthur

    2017-09-01

    The ternary selenide Ba12In4Se20 was synthesized by reaction of BaSe, In2Se3, and Se at 1023 K. Single-crystal X-ray diffraction revealed a trigonal structure (space group R 3 bar, Z = 6, a = 10.0360(6) Å, c = 78.286(4) Å at room temperature) consisting of one-dimensional stacks of InSe4 tetrahedra, In2Se7 double tetrahedra, selenide Se2- anions, and diselenide Se22- anions, with Ba2+ cations in the intervening spaces. The selenide Ba12In4Se20 can be derived from the corresponding sulfide Ba12In4S19 by replacing one monoatomic Ch2- anion with a diatomic Ch22- anion. An optical band gap of 1.70(2) eV, consistent with the dark red colour of the crystals, was deduced from the UV-vis-NIR diffuse reflectance spectrum.

  10. 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

  11. Structural Transformation of Hexagonal (0001)BaTiO3 Ceramics to Tetragonal (111)BaTiO3 Ceramics

    NASA Astrophysics Data System (ADS)

    Watanabe, Takayuki; Shimada, Mikio; Aiba, Toshiaki; Yabuta, Hisato; Miura, Kaoru; Oka, Kengo; Azuma, Masaki; Wada, Satoshi; Kumada, Nobuhiro

    2011-09-01

    A ceramic slurry that contains a 6H-type Ba(Ti0.95Mn0.05)O3 powder was casted into a plaster mold under 10 T magnetic field to form a green compact of (0001)-oriented Ba(Ti0.95Mn0.05)O3. After sintering the green compact at 1300 °C in air, it was confirmed that the (0001)-oriented 6H-type perovskite structure transformed to a (111)-oriented 3C-type perovskite structure. The structural transformation was again examined using hexagonal BaTiO3 prepared by reducing pseudo-cubic BaTiO3 powder in H2 atmosphere. In this case, the preferred (0001) orientation was not confirmed for the green compacts. After sintering the green compacts at 1300 °C in air, mixed crystal orientations of (100)/(001) and (111) were observed for the resultant tetragonal BaTiO3 ceramics. This (100)/(001) orientation was suppressed by annealing the hexagonal BaTiO3 powder at 1000 °C before slip-casting, leading to highly (111)-oriented ceramics. It was found that the green compacts of (0001)-oriented hexagonal BaTiO3 can transform into (111)-oriented tetragonal BaTiO3 ceramics, maintaining the macroscopic crystal orientations due to a similar atomic stacking along [0001] of 6H-type BaTiO3 and [111] of 3C-type BaTiO3.

  12. 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.

  13. Stellar neutron capture cross sections of the Ba isotopes

    NASA Astrophysics Data System (ADS)

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

    1994-11-01

    The neutron capture cross sections of 134Ba, 135Ba, 136Ba, and 137Ba were measured in the energy range from 5 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li (p,n)7 Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4π barium fluoride detector. The cross section ratios were determined with an overall uncertainty of ~3%, an improvement by factors of 5 to 8 compared to existing data. Severe discrepancies were found with respect to previous results. As a new possibility in time of flight experiments, isomeric cross section ratios could be determined for 135Ba, 136Ba, and 137Ba. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=10 keV and 100 keV. These stellar cross sections were used in an s-process analysis. For the s-only isotopes 134Ba and 136Ba the Ns<σ> ratio was determined to 0.875+/-0.025. Hence, a significant branching of the s-process path at 134Cs can be claimed for the first time, in contrast to predictions from the classical approach. This branching yields information on the s-process temperature, indicating values around T8=2. The new cross sections are also important for the interpretation of barium isotopic anomalies, which were recently discovered in SiC grains of carbonaceous chondrite meteorites. Together with the results from previous experiments on tellurium and samarium, a general improvement of the Ns<σ> systematics in the mass range A=120-150 is achieved. This yields a more reliable separation of s- and r-process contributions for comparison with stellar observations, but reveals a 20% discrepancy with respect to the solar barium abundance.

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

    SciTech Connect

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

    2016-01-15

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

  15. Ba2TeO: A new layered oxytelluride

    DOE PAGES

    Besara, T.; Ramirez, D.; Sun, J.; ...

    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.

  16. Ba-hexaferrite Films for Next Generation Microwave Devices (invited)

    SciTech Connect

    Harris,V.; Chen, Z.; Chen, Y.; Yoon, S.; Sakai, T.; Geiler, A.; Yang, A.; He, Y.; Ziemer, K.; et al.

    2006-01-01

    Next generation magnetic microwave devices require ferrite films to be thick (>300 {mu}m), self-biased (high remanent magnetization), and low loss in the microwave and millimeter wave bands. Here we examine recent advances in the processing of thick Ba-hexaferrite (M-type) films using pulsed laser deposition (PLD), liquid-phase epitaxy, and screen printing. These techniques are compared and contrasted as to their suitability for microwave materials processing and industrial production. Recent advances include the PLD growth of BaM on wide-band-gap semiconductor substrates and the development of thick, self-biased, low-loss BaM films by screen printing.

  17. Double Resonance Spectroscopy of BaF Autoionizing Rydberg States

    NASA Astrophysics Data System (ADS)

    Barnum, Timothy J.; Grimes, David; Zhou, Yan; Field, Robert W.

    2015-06-01

    We have studied the ν=1 Rydberg states of BaF in the energy region E=38800-39100 wn (n*=15-25) via optical-optical double resonance spectroscopy. Rydberg states excited above the first ionization potential spontaneously autoionize and 138Ba19F+ ions are detected by TOF-MS. In addition, BaF possesses a particularly low ionization potential, which allows for the study of autoionization dynamics in the absence of predissociative decay. This work extends the assignments of core-penetrating Rydberg states of BaF (Jakubek and Field, 2000) for applications to state-selective ion production schemes. Polarization and Stark spectroscopy techniques will be discussed in the context of accurate and efficient assignment of spectra.

  18. Ferroelectric BaTiO3 nanoparticles: biosynthesis and characterization.

    PubMed

    Jha, Anal K; Prasad, K

    2010-01-01

    A new low-cost, green and reproducible Lactobacillus sp. assisted biosynthesis of BaTiO(3) nanoparticles is reported. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of BaTiO(3) nanoparticles. The apparent crystallite size and lattice strain are estimated from Williamson-Hall approach. XRD analysis of the compound indicated the formation of a single-phase tetragonal structure. Individual nanoparticles as well as a few aggregate having the size of 20-80 nm are found. A possible involved mechanism for the biosynthesis of nano-BaTiO(3) has also been proposed in which ROS as well as partial pressure of gaseous hydrogen (rH(2)) of the culture solution seems to play an important role in the process. Remarkable enhancement in dielectric properties was observed in BaTiO(3)/polyvinylidene fluoride (PVDF) nanocomposite.

  19. Octa-Coordination and the Aqueous Ba(2+) Ion.

    PubMed

    Chaudhari, Mangesh I; Soniat, Marielle; Rempe, Susan B

    2015-07-16

    The hydration structure of Ba(2+) ion is important for understanding blocking mechanisms in potassium ion channels. Here, we combine statistical mechanical theory, ab initio molecular dynamics simulations, and electronic structure methods to calculate the hydration free energy and local hydration structure of Ba(2+)(aq). The predicted hydration free energy (-304 ± 1 kcal/mol) agrees with the experimental value (-303 kcal/mol) when a maximally occupied, unimodal inner solvation shell is treated. In the local environment defined by the first shell of hydrating waters, Ba(2+) is directly and stably coordinated by eight (8) waters. Octa-coordination resembles the crystal structure of Ba(2+) and K(+) bound in potassium ion channels, but differs from the local hydration structure of K(+)(aq) determined earlier.

  20. Operability test report for 211BA flow proportional sampler

    SciTech Connect

    Weissenfels, R.D.

    1995-01-01

    This operability report will verify that the 211-BA flow proportional sampler functions as intended by design. The sampler was installed by Project W-007H and is part of BAT/AKART for the BCE liquid effluent stream.

  1. Effect of local environment on crossluminescence kinetics in SrF2:Ba and CaF2:Ba solid solutions

    NASA Astrophysics Data System (ADS)

    Terekhin, M. A.; Makhov, V. N.; Lebedev, A. I.; Sluchinskaya, I. A.

    2015-10-01

    Spectral and kinetic properties of extrinsic crossluminescence (CL) in SrF2:Ba(1%) and CaF2:Ba(1%) are compared with those of intrinsic CL in BaF2 and are analyzed taking into account EXAFS data obtained at the Ba LIII edge and results of first-principles calculations. The CL decay time was revealed to be longer in SrF2:Ba and CaF2:Ba compared to BaF2. This fact contradicts the expected acceleration of luminescence decay which could result from an increased overlap of wave functions in solid solutions due to shortening of the Ba-F distance obtained in both EXAFS measurements and first-principles calculations. This discrepancy is explained by the effect of migration and subsequent non-radiative decay of the Ba(5p) core holes in BaF2 and by decreasing of the probability of optical transitions between Ba(5p) states and the valence band in SrF2:Ba and CaF2:Ba predicted by first-principles calculations.

  2. 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.

  3. Beyond CP Violation: Hadronic Physics at BaBar

    SciTech Connect

    Sciolla, G.

    2005-03-14

    I report on recent studies of hadronic physics performed by the BaBar Collaboration. Emphasis is given to the measurement of the properties of newly discovered charmed hadrons and to the searches for light and heavy pentaquarks. I report on recent studies of hadronic physics performed by the BaBar Collaboration. Emphasis is given to the measurement of the properties of newly discovered charmed hadrons and to the searches for light and heavy pentaquarks.

  4. Kinetic and equilibrium Ba isotope fractionation during carbonate precipitation

    NASA Astrophysics Data System (ADS)

    van Zuilen, Kirsten; Mavromatis, Vasileios; Purgstaller, Bettina; Baldermann, Andre; Nägler, Thomas F.; Dietzel, Martin

    2017-04-01

    Variations in stable isotope ratios recorded in carbonates are widely used to reconstruct the physicochemical conditions, e.g., pH, temperature and redox conditions, prevailing at the time of carbonate mineral formation. Knowledge of isotope fractionation factors during mineral precipitation under varying environmental conditions is irremissible for the interpretation of isotope variations in natural sedimentary archives. However, experimentally derived fractionation factors, of for instance Ca isotopes, are often ambiguous and incommensurable due to differences in experimental parameters. Here, Ba isotope fractionation during carbonate mineral formation was investigated [1]. Time-resolved experiments of witherite (BaCO3) precipitation revealed an initial kinetic isotope effect with increasing Δ137/134Ba values of the ambient solution, following Rayleigh fractionation (αwitherite-fluid = 0.99993 ± 0.00004). After precipitation, the witherite crystals remained in contact with the ambient solution for about nine days. During this time, chemical steady state was achieved between solution and witherite; however, the Δ137/134Ba values of the solution decreased. At isotopic equilibrium, the ambient solution and the witherite crystals exhibited identical δ137/134Ba values, within the analytical uncertainty of ±0.04 ‰Ṫhis observation is interpreted as the result of continuous exchange of Ba2+ ions between witherite and solution after initial preferential uptake of the lighter Ba isotopes in the precipitating carbonates. Mass balance calculations indicate that the ion exchange affects several subsurface layers of the crystals. In summary, Ba isotope exchange between carbonate and ambient solution occurs at chemical equilibrium, and pristine isotopic signatures in carbonates may thus be reset at low temperatures. [1] Mavromatis et al. (2016) Geochim. Cosmochim. Acta 190, 72-84.

  5. 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).

  6. CONSTRAINING INTRACLUSTER GAS MODELS WITH AMiBA13

    SciTech Connect

    Molnar, Sandor M.; Umetsu, Keiichi; Ho, Paul T. P.; Koch, Patrick M.; Victor Liao, Yu-Wei; Lin, Kai-Yang; Liu, Guo-Chin; Nishioka, Hiroaki; Birkinshaw, Mark; Bryan, Greg; Haiman, Zoltan; Shang, Cien; Hearn, Nathan

    2010-11-10

    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 {beta} 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.

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

    PubMed

    Koczorowski, W; Grzela, T; Radny, M W; Schofield, S R; Capellini, G; Czajka, R; Schroeder, T; Curson, N J

    2015-04-17

    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. 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) 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 the 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 to temperatures of 470, 570, 670 and 770 K although a gradual ordering of the Ba layer is observed at 570 K and above, accompanied by a decrease in Ba layer density. Annealing above 770 K produces the 2D surface alloy phase accompanied by strain relief through monolayer height trench formation. An annealing temperature of 1070 K sees a further change in surface morphology but retention of the 2D surface alloy characteristic. These results are discussed in view of their possible implications for future semiconductor integrated circuit technology.

  8. Structural and dielectric properties of Ba 2YbTaO 6, Ba 2YSbO 6 and Ba 2EuZrO 5.5

    NASA Astrophysics Data System (ADS)

    Konopka, Janusz; Jose, Rajan; Wołcyrz, Marek

    2006-03-01

    Structural and dielectric properties of Ba2YbTaO6, Ba2YSbO6 and Ba2EuZrO5.5 perovskites are presented. Because these materials were suggested as prospective buffer layers and substrates for HTS electronic devices such as SIS structures etc., their chemical stability with YBa2Cu3O7-δ (YBCO) and Bi2Sr2CanCun+1Ox (n = 1, 2; BiSCCO) was examined up to processing temperatures of listed superconductors. All three materials were found to be chemically stable with both YBCO and BiSCCO. Moreover, addition of ca. 20% of these perovskites to YBCO did not have any detrimental effect on the transition temperature. Dielectric properties of all a.m. materials were determined with high accuracy by measuring resonant frequencies of completely filled dielectric cavities at frequencies up to 40 GHz and at temperatures from 60 K to 350 K. The dielectric permittivities for particular materials are as follows: Ba2YbTaO6 → ε‧ = 29.4; Ba2EuZrO5.5 → ε‧ = 30.8; Ba2YSbO6 → ε‧ = 13.5. In microwave range all materials exhibit low or moderate losses. However, at temperatures where HTS materials enter into superconducting state (80-130 K), they exhibit some unusual features (a kind of a phase transition), which may either help or hamper their suggested applications in HTS electronics [J. Konopka, I. Wolff, S.J. Lewandowski, J. Appl. Phys. 72 (1992) 218].

  9. Syntheses, crystal structures, and optical properties of CsBa5Ti2Se9Cl and CsBa2Cl5

    NASA Astrophysics Data System (ADS)

    Mesbah, Adel; Prakash, Jai; Malliakas, Christos D.; Lebègue, Sébastien; Badawi, Michael; Ibers, James A.

    2017-09-01

    The mixed-cation compounds CsBa5Ti2Se9Cl and CsBa2Cl5 were synthesized in the same solid-state reaction at 1173 K. CsBa5Ti2Se9Cl adopts the Cs3CoCl5 structure type in the tetragonal crystal system whereas CsBa2Cl5 crystallizes in the PbU2Se5 structure type in the monoclinic crystal system. The CsBa5Ti2Se9Cl structure displays both Cs/Ba and Se/Cl disorder. From optical absorption measurements CsBa5Ti2Se9Cl is an indirect wide-gap semiconductor. From theoretical calculations CsBa2Cl5 has a large band gap of 6.4 eV.

  10. 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.

  11. Decay Data Evaluation Project (DDEP): Updated evaluation of the 133Ba, 140Ba, 140La and 141Ce decay characteristics

    NASA Astrophysics Data System (ADS)

    Chechev, Valerii P.; Kuzmenko, Nikolai K.

    2017-09-01

    Within the Decay Data Evaluation Project (DDEP) an updated comprehensive assessment has been made of the decay characteristics of 133Ba, 140Ba, 140La, and 141Ce. Experimental data published up to 2016 along with other information (new compilations, analyses and corrections) were taken into account. Newly evaluated values of the half-lives and a number of other key decay characteristics are presented in this paper for all four radionuclides.

  12. 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.

  13. BaTiO3-Based Non-Reducible Low-Loss Dielectric Ceramics

    NASA Astrophysics Data System (ADS)

    Nakamura, Tomoyuki; Sano, Harunobu; Konoike, Takehiro; Tomono, Kunisaburo

    1999-09-01

    Dielectrics composed of BaTiO3-rare earth oxide-MgO havebeenstudied to design a non-reducible low-loss dielectricmaterial. Curie temperatures of dielectrics composed ofBaTiO3 Gd2O3 MgO were lowered by Gd2O3, which provided thedielectrics with low power loss. It was found that the addition ofBaZrO3 to BaTiO3 Gd2O3 MgO decreased the capacitance change withtemperature. Gd2O3 diffused easily into BaTiO3, but, it could noteasily diffuse into BaTiO3 to which BaZrO3 had been added. It wasconsidered that BaZrO3 prevented the Gd2O3 diffusion into BaTiO3,resulting the remains of ferroelectricity and reduced capacitancechange. Thus non-reducible and low power loss X7R dielectricceramics were developed.

  14. Synthesis and Characterization of Benzylidene Acetal-Type Bridged Nucleic Acids (BA-BNA).

    PubMed

    Kodama, Tetsuya; Morihiro, Kunihiko; Obika, Satoshi

    2014-09-08

    Benzylidene acetal-type bridged nucleic acids (BA-BNAs) have a bridged structure that cleaves upon exposure to appropriate external stimuli, which induces changes in oligonucleotide properties. In particular, duplex stability and resistance to enzymatic digestion vary depending on the incorporation number and/or position of BA-BNAs. This unit describes the synthesis of some types of BA-BNA thymine nucleosides and the corresponding BA-BNA phosphoramidites, as well as the incorporation of BA-BNA nucleosides into oligonucleotides. Moreover, typical procedures that induce property changes in each BA-BNA are described. 6-Nitroveratrylidene and 2-nitrobenzylidene acetal type BA-BNA respond to photoirradiation and subsequent thiol treatment. Benzylidene and 4-nitrobenzylidene acetal type BA-BNAs respond to acids and reducing agents, respectively. Every BA-BNA is derivatized into 4'-C-hydroxymethyl RNA by hydrolysis of the acetal-bridged structure. Copyright © 2014 John Wiley & Sons, Inc.

  15. Prediction of a stable half-metal ferromagnetic BaCl solid

    NASA Astrophysics Data System (ADS)

    Greschner, Michael J.; Klug, Dennis D.; Yao, Yansun

    2016-03-01

    The modification of Ba in BaCl compounds from alkaline-metal to transition- and half-metal behavior is explored. High-pressure structural changes in BaCl are predicted using an ab initio structure search method. Dynamically stable bcc and R -3 m forms of BaCl are predicted at 15 and 10 GPa, respectively. The BaCl forms are more stable than elemental Ba plus BaC l2 above ˜10 GPa. Ba in stable BaCl adopts transition-metal properties via an s -d transition. At ambient pressure the fcc structure is ferromagnetic, and the bcc structure is half metallic and ferromagnetic. The transition-metal electronic structure found is sufficient to support superconductivity, with Tc as high as 3.4 K near ambient pressure.

  16. Influence of excess Ba concentration on the dielectric nonlinearity in Mn and V-doped BaTiO3 multi layer ceramic capacitors

    NASA Astrophysics Data System (ADS)

    Yoon, Seok-Hyun; Kim, Sun-Jung; Kim, Sang-Hyuk; Kim, Doo-Young

    2013-12-01

    The effect of excess Ba concentration on the dielectric nonlinearity was investigated in Mn and V-doped BaTiO3 multi layer ceramic capacitors (MLCC) under the same grain size condition, which was described by the Preisach model utilizing the first order reversal curve (FORC) distribution. The high-field dielectric constant and its ac field dependence dramatically changed increasing to a maximum and then decreasing with the increase of Ba concentration. The saturation polarization which scales to the magnitude of spontaneous polarization also showed similar behavior. These results indicate that the dependence of the dielectric constant on the Ba concentration is associated with the variation of both domain wall contribution and the magnitude of the spontaneous polarization, which could be correlated with the same dependence on the Ba concentration of the reversible FORC distribution at zero bias and the irreversible FORC distribution near origin. In the corresponding bulk specimens of the dielectrics of MLCC, almost the same amount of the Ba2TiSi2O8 second phases were detected irrespective of Ba concentration, which shows that the excess Ba incorporate into BaTiO3. Thus, low and high Ba concentration corresponds to Ba-deficient and Ba-rich or Ti-deficient BaTiO3, respectively, which results in a small spontaneous polarization and low domain wall density. The intermediate Ba concentration for the maximum dielectric constant is supposed to be near stoichiometric condition in the ABO3 structure corresponding to large spontaneous polarization and high domain wall density. The excess Ba concentration and its resultant A/B stoichiometry is a crucial factor controlling dielectric properties.

  17. 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

  18. Preparation and crystal structure of Ba 2NF

    NASA Astrophysics Data System (ADS)

    Seibel, H.; Wagner, T. R.

    2004-08-01

    Single crystalline Ba 2NF was prepared by heating a mixture of KCuF 3 and Ba metal to 900°C under dynamic flow of N 2, followed by slow cooling from the melt. Crystals of Ba 2NF were dark violet in color and very air sensitive. X-ray diffraction experiments revealed that Ba 2NF is isostructural with rocksalt-type BaO, and has space group Fm-3 m (No. 225) with cell parameter of a=5.6796(19) Å, Z=2. X-ray data was collected on a Bruker SMART APEX 4k CCD Single Crystal Diffractometer at 100 K, using Mo( Kα) radiation. Structure refinement was carried out by full-matrix least squares on F2 on all data, to give R1=0.0194 (all data) and w R2=0.0433 for 3 parameters and 23 independent reflections. The final position assignments were analyzed via bond valence sum calculations.

  19. 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.

  20. Observation of the Nuclear Magnetic Octupole Moment of 137Ba+

    NASA Astrophysics Data System (ADS)

    Hoffman, Matthew

    Single trapped ions are ideal systems in which to test atomic physics at high precision, which can in turn be used for searches for violations of fundamental symmetries and physics beyond the standard model, in addition to quantum computation and a number of other applications. The ion is confined in ultra-high vacuum, is laser cooled to mK temperatures, and kept well isolated from the environment which allows these experimental efforts. In this thesis, a few diagnostic techniques will be discussed, covering a method to measure the linewidth of a narrowband laser in the presence of magnetic field noise, as well as a procedure to measure the ion's temperature using such a narrowband laser. This work has led to two precision experiments to measure atomic structure in 138Ba+, and 137Ba+ discussed here. First, employing laser and radio frequency spectroscopy techniques in 138Ba+, we measured the Lande- gJ factor of the 5D5/2 level at the part-per-million level, the highest precision to date. Later, the development of apparatus to efficiently trap and laser cool 137Ba+ has enabled a measurement of the hyperfine splittings of the 5D3/2 manifold, culminating in the observation of the nuclear magnetic octupole moment of 137Ba+.

  1. Bismuthates: BaBiO3 and related superconducting phases

    NASA Astrophysics Data System (ADS)

    Sleight, Arthur W.

    2015-07-01

    BaBiO3 has the perovskite structure, but tilting of the BiO6 octahedra destroy the ideal cubic symmetry except at temperatures above 820 K. BaBiO3 is a diamagnetic semiconductor due to a charge density wave (CDW), which is equivalent to a Ba2Bi3+Bi5+O6 representation. Recent calculations and experimental results confirm that there is no significant deviation from the oxidation states of 3+ and 5+. Superconductivity with a Tc as high as 13 K occurs for BaPb1-xBixO3 phases where the 6s band is about 25% filled, and superconductivity with a Tc as high as 34 K occurs for Ba1-xKxBiO3 phases where the 6s band is about 35% filled. Structures in these two solid solutions can have cubic, tetragonal, orthorhombic, or monoclinic symmetry. However, superconductivity has only been observed when the symmetry is tetragonal.

  2. Thermoelectric properties of doped BaHfO{sub 3}

    SciTech Connect

    Dixit, Chandra Kr. E-mail: sharmarameshfgiet@gmail.com; Bhamu, K. C.; Sharma, Ramesh E-mail: sharmarameshfgiet@gmail.com

    2016-05-06

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

  3. Flux Pinning of Y-Ba-Cu-O Films Doped With BaZrO3 Nanoparticles by Multilayer and Single Target Methods (Postprint)

    DTIC Science & Technology

    2007-06-01

    AFRL-RZ-WP-TP-2012-0130 FLUX PINNING OF Y-Ba-Cu-O FILMS DOPED WITH BaZrO3 NANOPARTICLES BY MULTILAYER AND SINGLE TARGET METHODS (POSTPRINT...To) February 2012 Journal Article Postprint 04 April 2005 – 04 April 2007 4. TITLE AND SUBTITLE FLUX PINNING OF Y-Ba-Cu-O FILMS DOPED WITH BaZrO3...effort was completed in 2007. 14. ABSTRACT The superconducting properties of YBa2Cu3O7-x (YBCO or 123) thin films doped with BaZrO3 (BZO

  4. Nature of the Transient BaF2-Related Phases in the "BaF2" Processing of Ba2YCu3O7-x Superconductors

    SciTech Connect

    Wong-Ng, W.; Levin, I.; Cook, L. P.; Feenstra, Roeland

    2006-01-01

    Transient BaF{sub 2}-based oxyfluoride phases are thought to play a critical role in the formation of the c-textured Ba{sub 2}YCu{sub 3}O{sub 7-x} layers of coated conductors. In situ high-temperature x-ray diffraction from the precursor films containing pure BaF{sub 2} as well as pseudobinary BaF{sub 2-Y}, BaF{sub 2-}Cu, and Y-Cu mixtures and heat treated in water vapor under reduced conditions revealed that the transient BaF{sub 2}-based superstructures, similar to those observed during formation of Ba{sub 2}Cu{sub 3}O{sub 7-x}, develop even from the pure BaF{sub 2} precursor. These superstructures results from the dissolution of oxygen in BaF{sub 2} leading to formation of the oxyfluoride phase, Ba(F{sub 2-2x}{open_square}{sub x})O{sub x}, with an ordered arrangement of O, F, and F vacancies.

  5. 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.

  6. BaH molecular spectroscopy with relevance to laser cooling

    NASA Astrophysics Data System (ADS)

    Tarallo, M. G.; Iwata, G. Z.; Zelevinsky, T.

    2016-03-01

    We describe a simple experimental apparatus for laser ablation of barium monohydride (BaH) molecules and the study of their rovibrational spectra relevant to direct laser cooling. BaH is a promising candidate for laser cooling and ultracold fragmentation, both of which are precursors to novel experiments in many-body physics and precision measurement. We present a detailed analysis of the properties of ablation plumes that can improve the understanding of surface ablation and deposition technologies. A range of absorption spectroscopy and collisional thermalization regimes has been studied. We directly measured the Franck-Condon factor of the B 2Σ+(v'=0 ) ←X 2Σ+(v''=1 ) cycling transition. Prospects for production of a high luminosity cryogenic BaH beam are outlined.

  7. 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.

  8. 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.

  9. Reflectors for canning a BaF 2 crystal

    NASA Astrophysics Data System (ADS)

    Sinha, B. K.; Bhattacharya, R.

    1989-03-01

    The performance of BaF 2 crystals with various reflectors like teflon tape, ZrO 2, Al 2O 3 and CaF 2 powders is tested by measuring the energy and time resolution at different energies. It is shown that CaF 2 powder is a somewhat better reflector than the Al 2O 3 powder so far used by different workers. It is also seen that the reflectivity of CaF 2 powder for the BaF 2 emission spectrum is not much inferior to that of teflon tape which is, however, the best reported so far. Based on these observations a method of canning a BaF 2 crystal is proposed.

  10. Magnetism in BaCoS{sub 2}

    SciTech Connect

    Mandrus, D.; Chakoumakos, B.C.; Fernandez-Baca, J.A.; Nagler, S.E.; Sales, B.C.; Sarrao, J.L.

    1996-08-01

    BaCoS{sub 2} is a layered Mott-Hubbard insulator that orders antiferromagnetically near 300 K. We report magnetic susceptibility measurements on polycrystalline BaCoS{sub 2} from 77 K to 800 K, and in- and out-of-plane measurements on single crystals from 2 K to 350 K. We also report a powder neutron refinement of the magnetic structure of BaCoS{sub 2}. The neutron measurements indicate that the moments lie in the plane, and that the magnetic unit cell is the same as the (orthorhombic) chemical cell. The ordered moment obtained from the neutron refinement is close to 3 {mu}{sub B} indicating that the Co ions are in the high-spin (S = 3/2) configuration. The effective moment inferred from the high temperature susceptibility, p = 5.26 {mu}{sub B} is also consistent with high-spin Co{sup +2}.

  11. 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

  12. The BaBar instrumented flux return performance: lessons learned

    NASA Astrophysics Data System (ADS)

    Anulli, F.; Bagnasco, S.; Baldini, R.; Band, H. R.; Bionta, R.; Brau, J. E.; Brigljević, V.; Buzzo, A.; Calcaterra, A.; Carpinelli, M.; Cartaro, C.; Cavallo, N.; Crosetti, G.; de Sangro, R.; De Nardo, G.; Eichenbaum, A.; Fabozzi, F.; Falciai, D.; Ferrarotto, F.; Ferroni, F.; Finocchiaro, G.; Forti, F.; Frey, R.; Gatto, C.; Grauges, E.; Iakovlev, N. I.; Iwasaki, M.; Johnson, J. R.; Lange, D. J.; Lista, L.; Lo Vetere, M.; Lu, C.; Macri, M.; Messner, R.; Moore, T. B.; Morganti, S.; Neri, N.; Neal, H.; Palano, A.; Paoloni, E.; Paolucci, P.; Passaggio, S.; Pastore, F. C.; Patteri, P.; Peruzzi, I.; Piccolo, M.; Piccolo, D.; Piredda, G.; Robutti, E.; Roodman, A.; Santroni, A.; Sciacca, C.; Sinev, N. B.; Strom, D.; Soha, A.; Tosi, S.; Va'vra, J.; Wisniewski, W. J.; Wright, D. M.; Xie, Y.; Zallo, A.

    2002-11-01

    The BaBar Collaboration has operated an instrumented flux return (IFR) system covering over 2000 m2 with resistive plate chambers (RPCs) for nearly 3 years. The chambers are constructed of bakelite sheets separated by 2 mm. The inner surfaces are coated with linseed oil. This system provides muon and neutral hadron detection for BaBar. Installation and commissioning were completed in 1998, and operation began mid-year 1999. While initial performance of the system reached design, over time, a significant fraction of the RPCs demonstrated significant degradation, marked by increased currents and reduced efficiency. A coordinated effort of investigations have identified many of the elements responsible for the degradation. This article presents our current understanding of the aging process of the BaBar RPCs along with the action plan to combat performance degradation of the IFR system.

  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. 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.

  15. 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.

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

    PubMed

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

    2012-07-16

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

  17. 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.

  18. Elevated bile acids in newborns with Biliary Atresia (BA).

    PubMed

    Zhou, Kejun; Lin, Na; Xiao, Yongtao; Wang, Yang; Wen, Jie; Zou, Gang-Ming; Gu, Xuefan; Cai, Wei

    2012-01-01

    Biliary Atresia (BA), a result from inflammatory destruction of the intrahepatic and extrahepatic bile ducts, is a severe hepatobiliary disorder unique to infancy. Early diagnosis and Kasai operation greatly improve the outcome of BA patients, which encourages the development of early screening methods. Using HPLC coupled tandem mass spectrometry, we detected primary bile acids content in dried blood spots obtained from 8 BA infants, 17 neonatal jaundice and 292 comparison infants at 3-4 days of life. Taurocholate (TC) was significantly elevated in biliary atresia infants (0.98 ± 0.62 µmol/L) compared to neonatal jaundice (0.47 ± 0.30 µmol/L) and comparison infants (0.43 ± 0.40 µmol/L), with p=0.0231 and p=0.0016 respectively. The area under receiver operating characteristic (ROC) curve for TC to discriminate BA and comparison infants was 0.82 (95% confidence interval: 0.72-0.92). A cutoff of 0.63 µmol/L produced a sensitivity of 79.1% and specificity of 62.5%. The concentrations of total bile acids were also raised significantly in BA compared to comparison infants (6.62 ± 3.89 µmol/L vs 3.81 ± 3.06 µmol/L, p=0.0162), with the area under ROC curve of 0.75 (95% confidence interval: 0.61-0.89). No significant difference was found between the bile acids of neonatal jaundice and that of comparison infants. The early increase of bile acids indicates the presentation of BA in the immediate newborn period and the possibility of TC as newborn screening marker.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Quasiclassical calculation of the chemical reaction Ba+C3H7Br→BaBr+C3H7

    NASA Astrophysics Data System (ADS)

    Jiang, Yong-Chao; Li, Gui-Xia; Shi, Xiao-Feng; Huang, Shu-Lai

    2012-12-01

    The quasi-classical trajectory (QCT) method based on the extended London—Eyring—Polanyi—Sato potential energy surface is used to investigate the product vibrational distribution, angular distribution and angle-resolved kinetic distribution of the reaction Ba+C3H7Br→BaBr+C3H7 at 2.58 kcal/mol. The calculated results show that the product BaBr vibrational distribution is quite hot, the vibrational population peaks are located at v = 12, and the angular product distribution tends to backward scattering. The calculated angle-resolved kinetic distribution shows that the kinetic distribution is obviously related to angle. The QCT results are always qualitatively acceptable and sometimes even quantitatively.

  5. Synthesis, structural characterization and optical properties of new compounds: Centrosymmetric Ba2GaMQ5 (M=Sb,Bi; Q=Se,Te), Ba2InSbTe5 and noncentrosymmetric Ba2InSbSe5

    NASA Astrophysics Data System (ADS)

    Hao, Wenyu; Mei, Dajiang; Yin, Wenlong; Feng, Kai; Yao, Jiyong; Wu, Yicheng

    2013-02-01

    The six compounds Ba2GaMQ5 (M=Sb,Bi; Q=Se,Te) and Ba2InSbQ5 (Q=Se,Te) have been synthesized for the first time. Ba2GaMQ5 (M=Sb,Bi; Q=Se,Te) and Ba2InSbTe5 crystallize in the centrosymmetric space group Pnma, while Ba2InSbSe5 belongs to the noncentrosymmetric polar space group Cmc21. The structures of the six new compounds contain infinite [MM]4-∞1 anionic chains built by MQ4 (M'=Ga,In) tetrahedra and heavily distorted M'Q6 (M'=Sb,Bi) octahedra. Ba2InSbSe5 possesses a band gap of 1.92(5) eV and exhibits a weak powder second harmonic generation signal using the 2090 nm laser as fundamental wavelength.

  6. 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.

  7. 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.

  8. Phase Transitions in Quasi-one-dimensional Selenide BaNbSe 3and Superconductivity in BaNb 2Se 5

    NASA Astrophysics Data System (ADS)

    Ohtani, T.; Honji, S.; Takano, M.

    1997-08-01

    Samples with various compositions around BaNbSe3were prepared. X-ray analysis revealed that the compound is stable at the composition of BaNb0.80Se3, which formally requires Nb5+ions (d0). The single-phase region extends to the composition BaNb0.95Se3. A semiconductor-to-metal transition was observed at ∼140 K in BaNb0.95Se3. Seebeck measurements showed that the dominant carriers were electrons, which are considered to originate from Nb4+ions (d1) coexisting with Nb5+ions. On the basis of detailed phase study, the transition was revealed to be intrinsic to BaNb0.95Se3with a very slight Ba deficiency. BaNb0.95Se3with a slight Ba excess shows a semiconductor-to-semiconductor transition at 200-300 K. Seebeck measurements showed that the dominant carriers are electrons above the transition and are holes below the transition. A new compound, BaNb2Se5with a BaTa2S5-type structure, was found to show superconductivity at 2.5 K.

  9. Barium stable isotopes in the global ocean: Tracer of Ba inputs and utilization

    NASA Astrophysics Data System (ADS)

    Hsieh, Yu-Te; Henderson, Gideon M.

    2017-09-01

    Barium has been used as a biogeochemical tracer for alkalinity, productivity, and riverine inputs in the ocean, but its oceanic cycle remains poorly constrained. Barium stable isotope measurements may improve the use of Ba as a tracer and better constrain the cycling of Ba, but data are only available in limited regions of the oceans. In this study, we present dissolved seawater Ba isotopic compositions in a sample collection spanning the North Atlantic, South Atlantic, North Pacific and Southern Oceans. Compiled global upper-ocean [Ba] data show a relatively constant [Ba] (35-45 nM) in the near-surface waters throughout the global ocean, with the exception of areas near river inputs or strong upwelling. The relatively uniform distribution of [Ba] in the upper ocean seawater indicates that Ba removal is slow relative to supply and mixing, and implies that near-surface Ba isotope values are controlled by basin-scale balances rather than by regional or short-term processes. Seawater Ba isotopic compositions show a large variation of δ 138 / 134 Ba values ranging from 0.24 to 0.65‰, and a tight relationship with [Ba]. This global relationship can be simply modelled assuming a primary deep Southern Ocean source for Ba to yield a maximum isotope fractionation of α = 1.00058 ± 0.00010 (α =seawater 138/134Ba/particle 138/134Ba). This suggested isotope fractionation during Ba removal from seawater is larger than implied by laboratory measurement during barite formation, suggesting additional fractionating phases or a two-stage fractionation process. Riverine input from the Rio de la Plata to the South Atlantic has a signature of δ 138 / 134 Ba = - 0.06- 0.11 ‰, which is too light to explain the heavy values (>0.58‰) observed in the surface open ocean. Globally, the Ba isotope composition of the upper ocean waters is correlated with the fraction of Ba utilization at the basin scale (which varies from <15 to 70% at sites studied here). In the deep Atlantic Ocean

  10. 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.

  11. R-Ferrite-type barium cobalt stannate, BaCo2Sn4O11

    PubMed Central

    Yamane, Hisanori; Ono, Takeshi; Yamada, Takahiro

    2008-01-01

    BaCo2Sn4O11 is isotypic with R-ferrite, BaTi2Fe4O11. The Co atoms fully occupy trigonal–bipyramidal sites () and are disordered with Sn atoms in octa­hedral sites (.2/m symmetry), as represented in the formula BaCoSn2(Co0.34Sn0.66)4O11. Ba atoms are situated in a 12-fold coordinated site ( symmetry). PMID:21200980

  12. Antiferroelectric-to-paraelectric transition in BaFCl

    NASA Astrophysics Data System (ADS)

    Sundarakkannan, B.; Kesavamoorthy, R.; Adelene Nisha, J.; Sridharan, V.; Sivakumar, T.

    1998-05-01

    Thermoanalytical investigations are carried out on the flux-grown BaFCl crystals. An endothermic peak at 725 °C and 1.2% weight loss in the temperature range from 730 to 860 °C is observed in differential thermal analysis and thermogravimetric analysis measurements. Heating rate dependency of the endotherm peak position and that of weight loss onset temperature indicate that these two processes are independent from one another. Endotherm is attributed to the antiferroelectric to paraelectric transition in BaFCl. High-temperature Raman scattering, high-temperature x-ray diffraction (XRD) measurements and thermomechanical analysis show that BaFCl has no structural transition from 25 to 800 °C. Our results indicate order-disorder type transition. We propose the origin of the dipole to be the displacement of a Ba ion center from the nonpolar site, viz. anionic cage charge center. Weight loss is attributed to the evolution of halides with the activation energy of 1.57 eV. The weight loss results in the shrinkage of the unit cell as determined by XRD, leading to the shifting of the endotherm peak to 823 °C. The signature of defects produced by the evolution of halide is seen in optical absorption spectra.

  13. Backscatter Mossbauer Spectrometer (BaMS) for extraterrestrial applications

    NASA Technical Reports Server (NTRS)

    Agresti, D. G.; Shelfer, T. D.; Pimperl, M. M.; Wills, E. L.; Shen, M. H.; Morris, R. V.

    1993-01-01

    Mossbauer spectroscopy is a nuclear gamma resonance technique particularly well suited to the study of materials that contain iron (Fe-57). It can provide information on the oxidation state of iron as well as the type and proportion of iron-containing mineral species in a sample of interest. Iron Mossbauer spectroscopy (FeMS) has been applied to samples believed to have come from Mars (SNC meteorites) and has been helpful in refining the choice among putative Martian surface materials by suggesting a likely nanophase component of the Martian regolity. FeMS spectrum of a Martial analogue material (Hawaiian palagonite) is shown; it is dominated by ferric-bearing phases and shows evidence of a nanophase component. FeMS has also been applied to lunar materials. It can be used to measure the maturity of lunar surface material and has been proposed as a prospector for lunar ilmenite, an oxygen resource mineral. Several years ago we suggested a backscatter Mossbauer spectrometer (BaMS) for a Mars rover mission. Backscatter design was selected as most appropriate for in-situ application because no sample preparation is required. Since that time, we have continued to develop the BaMS instrument in anticipation that it would eventually find a home on a NASA planetary mission. Gooding proposed BaMS as a geochemistry instrument on MESUR. More recently, an LPI workshop has recommended that BaMS be included in a three-instrument payload on the next (1996?) lunar lander.

  14. The BaBar detector: Upgrades, operation and performance

    SciTech Connect

    Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; del Amo Sanchez, P.; Gaillard, J. -M.; Hicheur, A.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prudent, X.; Robbe, P.; Tisserand, V.; Zghiche, A.; Grauges, E.; Garra Tico, J.; Lopez, L.; Martinelli, M.; Palano, A.; Pappagallo, M.; Pompili, A.; Chen, G. P.; Chen, J. C.; Qi, N. D.; Rong, G.; Wang, P.; Zhu, Y. S.; Eigen, G.; Stugu, B.; Sun, L.; Abrams, G. S.; Battaglia, M.; Borgland, A. W.; Breon, A. B.; Brown, D. N.; Button-Shafer, J.; Cahn, R. N.; Charles, E.; Clark, A. R.; Day, C. T.; Furman, M.; Gill, M. S.; Groysman, Y.; Jacobsen, R. G.; Kadel, R. W.; Kadyk, J. A.; Kerth, L. T.; Kolomensky, Yu. G.; Kral, J. F.; Kukartsev, G.; LeClerc, C.; Levi, M. E.; Lynch, G.; Merchant, A. M.; Mir, L. M.; Oddone, P. J.; Orimoto, T. J.; Osipenkov, I. L.; Pripstein, M.; Roe, N. A.; Romosan, A.; Ronan, M. T.; Shelkov, V. G.; Suzuki, A.; Tackmann, K.; Tanabe, T.; Wenzel, W. A.; Zisman, M.; Barrett, M.; Bright-Thomas, P. G.; Ford, K. E.; Harrison, T. J.; Hart, A. J.; Hawkes, C. M.; Knowles, D. J.; Morgan, S. E.; O'Neale, S. W.; Penny, R. C.; Smith, D.; Soni, N.; Watson, A. T.; Watson, N. K.; Goetzen, K.; Held, T.; Koch, H.; Kunze, M.; Lewandowski, B.; Pelizaeus, M.; Peters, K.; Schmuecker, H.; Schroeder, T.; Steinke, M.; Fella, A.; Antonioli, E.; Boyd, J. T.; Chevalier, N.; Cottingham, W. N.; Foster, B.; Mackay, C.; Walker, D.; Abe, K.; Asgeirsson, D. J.; Cuhadar-Donszelmann, T.; Fulsom, B. G.; Hearty, C.; Knecht, N. S.; Mattison, T. S.; McKenna, J. A.; Thiessen, D.; Khan, A.; Kyberd, P.; McKemey, A. K.; Randle-Conde, A.; Saleem, M.; Sherwood, D. J.; Teodorescu, L.; Blinov, V. E.; Bukin, A. D.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Korol, A. A.; Kravchenko, E. A.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Telnov, V. I.; Todyshev, K. Yu.; Yushkov, A. N.; Best, D. S.; Bondioli, M.; Bruinsma, M.; Chao, M.; Curry, S.; Eschrich, I.; Kirkby, D.; Lankford, A. J.; Mandelkern, M.; Martin, E. C.; McMahon, S.; Mommsen, R. K.; Stoker, D. P.; Abachi, S.; Buchanan, C.; Hartfiel, B. L.; Weinstein, A. J. R.; Atmacan, H.; Foulkes, S. D.; Gary, J. W.; Layter, J.; Liu, F.; Long, O.; Shen, B. C.; Vitug, G. M.; Wang, K.; Yasin, Z.; Zhang, L.; Hadavand, H. K.; Hill, E. J.; Paar, H. P.; Rahatlou, S.; Schwanke, U.; Sharma, V.; Berryhill, J. W.; Campagnari, C.; Cunha, A.; Dahmes, B.; Hong, T. M.; Kovalskyi, D.; Kuznetsova, N.; Levy, S. L.; Lu, A.; Mazur, M. A.; Richman, J. D.; Verkerke, W.; Beck, T. W.; Beringer, J.; Eisner, A. M.; Flacco, C. J.; Grillo, A. A.; Grothe, M.; Heusch, C. A.; Kroseberg, J.; Lockman, W. S.; Martinez, A. J.; Nesom, G.; Schalk, T.; Schmitz, R. E.; Schumm, B. A.; Seiden, A.; Spencer, E.; Spradlin, P.; Turri, M.; Walkowiak, W.; Wang, L.; Wilder, M.; Williams, D. C.; Wilson, M. G.; Winstrom, L. O.; Chen, E.; Cheng, C. H.; Doll, D. A.; Dorsten, M. P.; Dvoretskii, A.; Echenard, B.; Erwin, R. J.; Fang, F.; Flood, K.; Hitlin, D. G.; Metzler, S.; Narsky, I.; Oyang, J.; Piatenko, T.; Porter, F. C.; Ryd, A.; Samuel, A.; Yang, S.; Zhu, R. Y.; Andreassen, R.; Devmal, S.; Geld, T. L.; Jayatilleke, S.; Mancinelli, G.; Meadows, B. T.; Mishra, K.; Sokoloff, M. D.; Abe, T.; Antillon, E. A.; Barillari, T.; Becker, J.; Blanc, F.; Bloom, P. C.; Chen, S.; Clifton, Z. C.; Derrington, I. M.; Destree, J.; Dima, M. O.; Ford, W. T.; Gaz, A.; Gilman, J. D.; Hachtel, J.; Hirschauer, J. F.; Johnson, D. R.; Kreisel, A.; Nagel, M.; Nauenberg, U.; Olivas, A.; Rankin, P.; Roy, J.; Ruddick, W. O.; Smith, J. G.; Ulmer, K. A.; van Hoek, W. C.; Wagner, S. R.; West, C. G.; Zhang, J.; Ayad, R.; Blouw, J.; Chen, A.; Eckhart, E. A.; Harton, J. L.; Hu, T.; Toki, W. H.; Wilson, R. J.; Winklmeier, F.; Zeng, Q. L.; Altenburg, D.; Feltresi, E.; Hauke, A.; Jasper, H.; Karbach, M.; Merkel, J.; Petzold, A.; Spaan, B.; Wacker, K.; Brandt, T.; Brose, J.; Colberg, T.; Dahlinger, G.; Dickopp, M.; Eckstein, P.; Futterschneider, H.; Kaiser, S.; Kobel, M. J.; Krause, R.; Müller-Pfefferkorn, R.; Mader, W. F.; Maly, E.; Nogowski, R.; Otto, S.; Schubert, J.; Schubert, K. R.; Schwierz, R.; Sundermann, J. E.; Volk, A.; Wilden, L.; Bernard, D.; Brochard, F.; Cohen-Tanugi, J.; Dohou, F.; Ferrag, S.; Latour, E.; Mathieu, A.; Renard, C.; Schrenk, S.; T'Jampens, S.; Thiebaux, Ch.; Vasileiadis, G.; Verderi, M.; Anjomshoaa, A.; Bernet, R.; Clark, P. J.; Lavin, D. R.; Muheim, F.; Playfer, S.; Robertson, A. I.; Swain, J. E.; Watson, J. E.; Xie, Y.; Andreotti, D.; Andreotti, M.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Carassiti, V.; Cecchi, A.; Cibinetto, G.; Cotta Ramusino, A.; Evangelisti, F.; Fioravanti, E.; Franchini, P.; Garzia, I.; Landi, L.; Luppi, E.; Malaguti, R.; Negrini, M.; Padoan, C.; Petrella, A.; Piemontese, L.; Santoro, V.; Sarti, A.; Anulli, F.; Baldini-Ferroli, R.; Calcaterra, A.; Finocchiaro, G.; Pacetti, S.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Rama, M.; de Sangro, R.; Santoni, M.; Zallo, A.; Bagnasco, S.; Buzzo, A.; Capra, R.; Contri, R.; Crosetti, G.; Lo Vetere, M.; Macri, M. M.; Minutoli, S.; Monge, M. R.; Musico, P.; Passaggio, S.; Pastore, F. C.; Patrignani, C.; Pia, M. G.; Robutti, E.; Santroni, A.; Tosi, S.; Bhuyan, B.; Prasad, V.; Bailey, S.; Brandenburg, G.; Chaisanguanthum, K. S.; Lee, C. L.; Morii, M.; Won, E.; Wu, J.; Adametz, A.; Dubitzky, R. S.; Marks, J.; Schenk, S.; Uwer, U.; Klose, V.; Lacker, H. M.; Aspinwall, M. L.; Bhimji, W.; Bowerman, D. A.; Dauncey, P. D.; Egede, U.; Flack, R. L.; Gaillard, J. R.; Gunawardane, N. J. W.; Morton, G. W.; Nash, J. A.; Nikolich, M. B.; Panduro Vazquez, W.; Sanders, P.; Smith, D.; Taylor, G. P.; Tibbetts, M.; Behera, P. K.; Chai, X.; Charles, M. J.; Grenier, G. J.; Hamilton, R.; Lee, S. -J.; Mallik, U.; Meyer, N. T.; Chen, C.; Cochran, J.; Crawley, H. B.; Dong, L.; Eyges, V.; Fischer, P. -A.; Lamsa, J.; Meyer, W. T.; Prell, S.; Rosenberg, E. I.; Rubin, A. E.; Gao, Y. Y.; Gritsan, A. V.; Guo, Z. J.; Lae, C. K.; Schott, G.; Albert, J. N.; Arnaud, N.; Beigbeder, C.; Breton, D.; Davier, M.; Derkach, D.; Dû, S.; Firmino da Costa, J.; Grosdidier, G.; Höcker, A.; Laplace, S.; Le Diberder, F.; Lepeltier, V.; Lutz, A. M.; Malaescu, B.; Nief, J. Y.; Petersen, T. C.; Plaszczynski, S.; Pruvot, S.; Roudeau, P.; Schune, M. H.; Serrano, J.; Sordini, V.; Stocchi, A.; Tocut, V.; Trincaz-Duvoid, S.; Wang, L. L.; Wormser, G.; Bionta, R. M.; Brigljević, V.; Lange, D. J.; Simani, M. C.; Wright, D. M.; Bingham, I.; Burke, J. P.; Chavez, C. A.; Coleman, J. P.; Forster, I. J.; Fry, J. R.; Gabathuler, E.; Gamet, R.; George, M.; Hutchcroft, D. E.; Kay, M.; Parry, R. J.; Payne, D. J.; Schofield, K. C.; Sloane, R. J.; Touramanis, C.; Azzopardi, D. E.; Bellodi, G.; Bevan, A. J.; Clarke, C. K.; Cormack, C. M.; Di Lodovico, F.; Dixon, P.; George, K. A.; Menges, W.; Potter, R. J. L.; Sacco, R.; Shorthouse, H. W.; Sigamani, M.; Strother, P.; Vidal, P. B.; Brown, C. L.; Cowan, G.; Flaecher, H. U.; George, S.; Green, M. G.; Hopkins, D. A.; Jackson, P. S.; Kurup, A.; Marker, C. E.; McGrath, P.; McMahon, T. R.; Paramesvaran, S.; Salvatore, F.; Vaitsas, G.; Winter, M. A.; Wren, A. C.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Griessinger, K.; Hafner, A.; Prencipe, E.; Allison, J.; Alwyn, K. E.; Bailey, D. S.; Barlow, N. R.; Barlow, R. J.; Chia, Y. M.; Edgar, C. L.; Forti, A. C.; Fullwood, J.; Hart, P. A.; Hodgkinson, M. C.; Jackson, F.; Jackson, G.; Kelly, M. P.; Kolya, S. D.; Lafferty, G. D.; Lyon, A. J.; Naisbit, M. T.; Savvas, N.; Weatherall, J. H.; West, T. J.; Williams, J. C.; Yi, J. I.; Anderson, J.; Farbin, A.; Hulsbergen, W. D.; Jawahery, A.; Lillard, V.; Roberts, D. A.; Schieck, J. R.; Simi, G.; Tuggle, J. M.; Blaylock, G.; Dallapiccola, C.; Hertzbach, S. S.; Kofler, R.; Koptchev, V. B.; Li, X.; Moore, T. B.; Salvati, E.; Saremi, S.; Staengle, H.; Willocq, S. Y.; Cowan, R.; Dujmic, D.; Fisher, P. H.; Henderson, S. W.; Koeneke, K.; Lang, M. I.; Sciolla, G.; Spitznagel, M.; Taylor, F.; Yamamoto, R. K.; Yi, M.; Zhao, M.; Zheng, Y.; Klemetti, M.; Lindemann, D.; Mangeol, D. J. J.; Mclachlin, S. E.; Milek, M.; Patel, P. M.; Robertson, S. H.; Biassoni, P.; Cerizza, G.; Lazzaro, A.; Lombardo, V.; Neri, N.; Palombo, F.; Pellegrini, R.; Stracka, S.; Bauer, J. M.; Cremaldi, L.; Eschenburg, V.; Kroeger, R.; Reidy, J.; Sanders, D. A.; Summers, D. J.; Zhao, H. W.; Godang, R.; Brunet, S.; Cote, D.; Nguyen, X.; Simard, M.; Taras, P.; Viaud, B.; Nicholson, H.; Cavallo, N.; De Nardo, G.; Fabozzi, F.; Gatto, C.; Lista, L.; Monorchio, D.; Onorato, G.; Paolucci, P.; Piccolo, D.; Sciacca, C.; Baak, M. A.; Raven, G.; Snoek, H. L.; Jessop, C. P.; Knoepfel, K. J.; LoSecco, J. M.; Wang, W. F.; Allmendinger, T.; Benelli, G.; Brau, B.; Corwin, L. A.; Gan, K. K.; Honscheid, K.; Hufnagel, D.; Kagan, H.; Kass, R.; Morris, J. P.; Rahimi, A. M.; Regensburger, J. J.; Smith, D. S.; Ter-Antonyan, R.; Wong, Q. K.; Blount, N. L.; Brau, J.; Frey, R.; Igonkina, O.; Iwasaki, M.; Kolb, J. A.; Lu, M.; Potter, C. T.; Rahmat, R.; Sinev, N. B.; Strom, D.; Strube, J.; Torrence, E.; Borsato, E.; Castelli, G.; Colecchia, F.; Crescente, A.; Dal Corso, F.; Dorigo, A.; Fanin, C.; Furano, F.; Gagliardi, N.; Galeazzi, F.; Margoni, M.; Marzolla, M.; Michelon, G.; Morandin, M.; Posocco, M.; Rotondo, M.; Simonetto, F.; Solagna, P.; Stevanato, E.; Stroili, R.; Tiozzo, G.; Voci, C.; Akar, S.; Bailly, P.; Ben-Haim, E.; Bonneaud, G.; Briand, H.; Chauveau, J.; Hamon, O.; John, M. J. J.; Lebbolo, H.; Leruste, Ph.; Malclès, J.; Marchiori, G.; Martin, L.; Ocariz, J.; Perez, A.; Pivk, M.; Prendki, J.; Roos, L.; Sitt, S.; Stark, J.; Thérin, G.; Vallereau, A.; Biasini, M.; Covarelli, R.; Manoni, E.; Pennazzi, S.; Pioppi, M.; Angelini, C.; Batignani, G.; Bettarini, S.; Bosi, F.; Bucci, F.; Calderini, G.; Carpinelli, M.; Cenci, R.; Cervelli, A.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Marchiori, G.; Morganti, M.; Morsani, F.; Paoloni, E.; Raffaelli, F.; Rizzo, G.; Sandrelli, F.; Triggiani, G.; Walsh, J. J.; Haire, M.; Judd, D.; Biesiada, J.; Danielson, N.; Elmer, P.; Fernholz, R. E.; Lau, Y. P.; Lu, C.; Miftakov, V.; Olsen, J.; Lopes Pegna, D.; Sands, W. R.; Smith, A. J. S.; Telnov, A. V.; Tumanov, A.; Varnes, E. W.; Baracchini, E.; Bellini, F.; Bulfon, C.; Buccheri, E.; Cavoto, G.; D'Orazio, A.; Di Marco, E.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gaspero, M.; Jackson, P. D.; Lamanna, E.; Leonardi, E.; Li Gioi, L.; Lunadei, R.; Mazzoni, M. A.; Morganti, S.; Piredda, G.; Polci, F.; del Re, D.; Renga, F.; Safai Tehrani, F.; Serra, M.; Voena, C.; Bünger, C.; Christ, S.; Hartmann, T.; Leddig, T.; Schröder, H.; Wagner, G.; Waldi, R.; Adye, T.; Bly, M.; Brew, C.; Condurache, C.; De Groot, N.; Franek, B.; Geddes, N. I.; Gopal, G. P.; Olaiya, E. O.; Ricciardi, S.; Roethel, W.; Wilson, F. F.; Xella, S. M.; Aleksan, R.; Bourgeois, P.; Emery, S.; Escalier, M.; Esteve, L.; Gaidot, A.; Ganzhur, S. F.; Giraud, P. -F.; Georgette, Z.; Graziani, G.; Hamel de Monchenault, G.; Kozanecki, W.; Langer, M.; Legendre, M.; London, G. W.; Mayer, B.; Micout, P.; Serfass, B.; Vasseur, G.; Yèche, Ch.; Zito, M.; Allen, M. T.; Akre, R.; Aston, D.; Azemoon, T.; Bard, D. J.; Bartelt, J.; Bartoldus, R.; Bechtle, P.; Becla, J.; Benitez, J. F.; Berger, N.; Bertsche, K.; Boeheim, C. T.; Bouldin, K.; Boyarski, A. M.; Boyce, R. F.; Browne, M.; Buchmueller, O. L.; Burgess, W.; Cai, Y.; Cartaro, C.; Ceseracciu, A.; Claus, R.; Convery, M. R.; Coupal, D. P.; Craddock, W. W.; Crane, G.; Cristinziani, M.; DeBarger, S.; Decker, F. J.; Dingfelder, J. C.; Donald, M.; Dorfan, J.; Dubois-Felsmann, G. P.; Dunwoodie, W.; Ebert, M.; Ecklund, S.; Erickson, R.; Fan, S.; Field, R. C.; Fisher, A.; Fox, J.; Franco Sevilla, M.; Fulsom, B. G.; Gabareen, A. M.; Gaponenko, I.; Glanzman, T.; Gowdy, S. J.; Graham, M. T.; Grenier, P.; Hadig, T.; Halyo, V.; Haller, G.; Hamilton, J.; Hanushevsky, A.; Hasan, A.; Hast, C.; Hee, C.; Himel, T.; Hryn'ova, T.; Huffer, M. E.; Hung, T.; Innes, W. R.; Iverson, R.; Kaminski, J.; Kelsey, M. H.; Kim, H.; Kim, P.; Kharakh, D.; Kocian, M. L.; Krasnykh, A.; Krebs, J.; Kroeger, W.; Kulikov, A.; Kurita, N.; Langenegger, U.; Leith, D. W. G. S.; Lewis, P.; Li, S.; Libby, J.; Lindquist, B.; Luitz, S.; Lüth, V.; Lynch, H. L.; MacFarlane, D. B.; Marsiske, H.; McCulloch, M.; McDonald, J.; Melen, R.; Menke, S.; Metcalfe, S.; Messner, R.; Moss, L. J.; Mount, R.; Muller, D. R.; Neal, H.; Nelson, D.; Nelson, S.; Nordby, M.; Nosochkov, Y.; Novokhatski, A.; O'Grady, C. P.; O'Neill, F. G.; Ofte, I.; Ozcan, V. E.; Perazzo, A.; Perl, M.; Petrak, S.; Piemontese, M.; Pierson, S.; Pulliam, T.; Ratcliff, B. N.; Ratkovsky, S.; Reif, R.; Rivetta, C.; Rodriguez, R.; Roodman, A.; Salnikov, A. A.; Schietinger, T.; Schindler, R. H.; Schwarz, H.; Schwiening, J.; Seeman, J.; Smith, D.; Snyder, A.; Soha, A.; Stanek, M.; Stelzer, J.; Su, D.; Sullivan, M. K.; Suzuki, K.; Swain, S. K.; Tanaka, H. A.; Teytelman, D.; Thompson, J. M.; Tinslay, J. S.; Trunov, A.; Turner, J.; van Bakel, N.; van Winkle, D.; Va'vra, J.; Wagner, A. P.; Weaver, M.; Weinstein, A. J. R.; Weber, T.; West, C. A.; Wienands, U.; Wisniewski, W. J.; Wittgen, M.; Wittmer, W.; Wright, D. H.; Wulsin, H. W.; Yan, Y.; Yarritu, A. K.; Yi, K.; Yocky, G.; Young, C. C.; Ziegler, V.; Chen, X. R.; Liu, H.; Park, W.; Purohit, M. V.; Singh, H.; Weidemann, A. W.; White, R. M.; Wilson, J. R.; Yumiceva, F. X.; Sekula, S. J.; Bellis, M.; Burchat, P. R.; Edwards, A. J.; Majewski, S. A.; Meyer, T. I.; Miyashita, T. S.; Petersen, B. A.; Roat, C.; Ahmed, M.; Ahmed, S.; Alam, M. S.; Bula, R.; Ernst, J. A.; Jain, V.; Liu, J.; Pan, B.; Saeed, M. A.; Wappler, F. R.; Zain, S. B.; Gorodeisky, R.; Guttman, N.; Peimer, D.; Soffer, A.; De Silva, A.; Lund, P.; Krishnamurthy, M.; Ragghianti, G.; Spanier, S. M.; Wogsland, B. J.; Eckmann, R.; Ritchie, J. L.; Ruland, A. M.; Satpathy, A.; Schilling, C. J.; Schwitters, R. F.; Wray, B. C.; Drummond, B. W.; Izen, J. M.; Kitayama, I.; Lou, X. C.; Ye, S.; Bianchi, F.; Bona, M.; Gallo, F.; Gamba, D.; Pelliccioni, M.; Bomben, M.; Borean, C.; Bosisio, L.; Cossutti, F.; Della Ricca, G.; Dittongo, S.; Grancagnolo, S.; Lanceri, L.; Poropat, P.; Rashevskaya, I.; Vitale, L.; Vuagnin, G.; Manfredi, P. F.; Re, V.; Speziali, V.; Frank, E. D.; Gladney, L.; Guo, Q. H.; Panetta, J.; Azzolini, V.; Lopez-March, N.; Martinez-Vidal, F.; Milanes, D. A.; Oyanguren, A.; Agarwal, A.; Albert, J.; Banerjee, Sw.; Bernlochner, F. U.; Brown, C. M.; Choi, H. H. F.; Fortin, D.; Fransham, K. B.; Hamano, K.; Kowalewski, R.; Lewczuk, M. J.; Nugent, I. M.; Roney, J. M.; Sobie, R. J.; Back, J. J.; Gershon, T. J.; Harrison, P. F.; Ilic, J.; Latham, T. E.; Mohanty, G. B.; Puccio, E.; Band, H. R.; Chen, X.; Cheng, B.; Dasu, S.; Datta, M.; Eichenbaum, A. M.; Hollar, J. J.; Hu, H.; Johnson, J. R.; Kutter, P. E.; Li, H.; Liu, R.; Mellado, B.; Mihalyi, A.; Mohapatra, A. K.; Pan, Y.; Pierini, M.; Prepost, R.; Scott, I. J.; Tan, P.; Vuosalo, C. O.; von Wimmersperg-Toeller, J. H.; Wu, S. L.; Yu, Z.; Greene, M. G.; Kordich, T. M. B.

    2013-11-01

    The BaBar detector operated successfully at the PEP-II asymmetric e+e- collider at the SLAC National Accelerator Laboratory from 1999 to 2008. This report covers upgrades, operation, and performance of the collider and the detector systems, as well as the trigger, online and offline computing, and aspects of event reconstruction since the beginning of data taking.

  15. PEM Fuel Cell System Replacement for BA-559O Battery

    DTIC Science & Technology

    2007-11-02

    H Power Corp. developed a fuel cell system to demonstrate that fuel cells can be effectively designed for missions requiring a high degree of...equivalent in size to that of a BA-5590 battery. The system comprised an air-cooled fuel cell stack, a metal-hydride-based fuel storage section, and a

  16. 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.

  17. 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.

  18. 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.

  19. Generator Coordinate Method Analysis of Xe and Ba Isotopes

    NASA Astrophysics Data System (ADS)

    Higashiyama, Koji; Yoshinaga, Naotaka; Teruya, Eri

    Nuclear structure of Xe and Ba isotopes is studied in terms of the quantum-number projected generator coordinate method (GCM). The GCM reproduces well the energy levels of high-spin states as well as low-lying states. The structure of the low-lying states is analyzed through the GCM wave functions.

  20. Backscatter Mossbauer Spectrometer (BaMS) for extraterrestrial applications

    NASA Astrophysics Data System (ADS)

    Agresti, D. G.; Shelfer, T. D.; Pimperl, M. M.; Wills, E. L.; Shen, M. H.; Morris, R. V.

    1993-06-01

    Mossbauer spectroscopy is a nuclear gamma resonance technique particularly well suited to the study of materials that contain iron (Fe-57). It can provide information on the oxidation state of iron as well as the type and proportion of iron-containing mineral species in a sample of interest. Iron Mossbauer spectroscopy (FeMS) has been applied to samples believed to have come from Mars (SNC meteorites) and has been helpful in refining the choice among putative Martian surface materials by suggesting a likely nanophase component of the Martian regolity. FeMS spectrum of a Martial analogue material (Hawaiian palagonite) is shown; it is dominated by ferric-bearing phases and shows evidence of a nanophase component. FeMS has also been applied to lunar materials. It can be used to measure the maturity of lunar surface material and has been proposed as a prospector for lunar ilmenite, an oxygen resource mineral. Several years ago we suggested a backscatter Mossbauer spectrometer (BaMS) for a Mars rover mission. Backscatter design was selected as most appropriate for in-situ application because no sample preparation is required. Since that time, we have continued to develop the BaMS instrument in anticipation that it would eventually find a home on a NASA planetary mission. Gooding proposed BaMS as a geochemistry instrument on MESUR. More recently, an LPI workshop has recommended that BaMS be included in a three-instrument payload on the next (1996?) lunar lander.

  1. 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.

  2. Measurements of Form Factors with the BaBar Experiment

    SciTech Connect

    Li, Selina Z.; /SLAC

    2011-08-25

    Selected recent results on measurements of form factors by the BaBar Collaboration are reviewed, including e{sup +}e{sup -} {yields} {eta}{prime}{gamma}, leptonic and semileptonic charm decays from data collected at or near the {Upsilon}(4S) resonance.

  3. Thermomechanical response of polycrystalline BaZrO{sub 3}.

    SciTech Connect

    Goretta, K. C.; Park, E. T.; Koritala, R. E.; Cuber, M. M.; Pascual, E. A.; Chen, N.; de Arellano-Lopez, A. R.; Routbort, J. L.; Univ. de Sevilla

    1998-01-01

    Thermomechanical properties of fine-grained, 96% dense, polycrystalline BaZrO{sub 3} specimens were studied. The average thermal expansion coefficient of BaZrO{sub 3} at 2511000{sup o}C was 7.72x10{sup -6}{sup o}C{sup -1}. At 25{sup o}C, Young's modulus was 240.5 GPa and the shear modulus was 97.2 GPa. These values decreased by {approx}10% with heating to 1015{sup o}C. Poisson's ratio was 0.237 and was independent of temperature. The BaZrO{sub 3} specimens exhibited a thermal expansion coefficient of about one half, and elastic moduli more than twice, those of polycrystalline high-temperature superconductors. Diffusional creep was observed when BaZrO{sub 3} was compressed at 1300-1400{sup o}C; the activation energy for steady-state deformation was 460{+-}30 kJ/mole. The mechanism was probably grain-boundary sliding, controlled by diffusion of one of the cations along grain boundaries. Deformation rates below 1000{sup o}C were too low to relax thermally generated stresses.

  4. LaBaNiO4: a Fermi glass

    NASA Astrophysics Data System (ADS)

    Schilling, A.; Dell'Amore, R.; Karpinski, J.; Bukowski, Z.; Medarde, M.; Pomjakushina, E.; Müller, K. A.

    2009-01-01

    Polycrystalline samples of LaSr1-xBaxNiO4 show a crossover from a state with metallic transport properties for x = 0 to an insulating state as x\\to 1 . The end member LaBaNiO4 with a nominal nickel Ni 3d7 configuration might therefore be regarded as a candidate for an antiferromagnetic insulator. However, we do not observe any magnetic ordering in LaBaNiO4 down to 1.5 K, and despite its insulating transport properties several other physical properties of LaBaNiO4 resemble those of metallic LaSrNiO4. Based on an analysis of electrical and thermal-conductivity data as well as magnetic-susceptibility and low-temperature specific-heat measurements, we suggest that LaBaNiO4 is a Fermi glass with a finite electron density of states at the Fermi level but these states are localized.

  5. Quaternary system SrO-CaO-BaO-CuO at 950 C. 2: Phase equilibria related to the substitution Sr/Ba in (Sr/Ba){sub 2}Ca{sub 2}Cu{sub 2}Cu{sub 3}O{sub 7} and (Sr/Ba){sub 2}CaCu{sub 2}O{sub 5} samples

    SciTech Connect

    Lebbou, K.; Abraham, R.; Trosset, S.; Cohen-Adad, M.T.

    1997-08-01

    A partial study of the solid-solid equilibria in the quaternary system BaO-SrO-CaO-CuO has been undertaken in order to determine the observed phases and their evolution when Ba is substituted for Sr in mixtures (Sr/Ba){sub 2}CaCu{sub 2}O{sub x} and (Sr/Ba){sub 2}Ca{sub 2}Cu{sub 3}O{sub x}. The temperature was fixed at 950 C and samples were elaborated under 1 bar of flowing oxygen. It has been shown that two four-phased domains exist in this quaternary system, including the following phases: ({und Ba}/Sr/Ca)CuO{sub 2}, ({und Sr/Ca}/Ba){sub 2}CuO{sub 3}, ({und Sr/Ca}/Ba){sub 14}Cu{sub 24}O{sub x}, and Ba{sub 4}CaCu{sub 3}O{sub 8} substituted Sr/Ca for the one and ({und Ba}/Sr/Ca)CuO{sub 2}, ({und Sr/Ca}/Ba){sub 2}CuO{sub 3}, ({und Sr/Ca}/Ba){sub 14}Cu{sub 24}O{sub x}, and ({und Sr/Ca}/Ba/)CuO{sub 2} for the other.

  6. 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 P-00...

  7. 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 P-00...

  8. 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 P-00...

  9. Core-corona PSt/P(BA-AA) composite particles by two-stage emulsion polymerization

    NASA Astrophysics Data System (ADS)

    Xie, Delong; Ren, Xiaolin; Zhang, Xinya; Liao, Shijun

    2016-03-01

    Raspberry-shaped composite particles with polystyrene (PSt) as core and poly(n-butyl acrylate-co-acrylic acid) (P(BA-AA)) as corona were synthesized via emulsion polymerization. The random copolymer, P(BA-AA), was pre-prepared and used as a polymeric surfactant, its emulsifying properties adjusted by changing the mass ratio of BA and AA. The morphology of the resulting core-corona composite particles, P(St/P(BA-AA)), could be regulated and controlled by varying the concentrations of P(BA-AA) or the mass ratio of BA:AA in P(BA-AA). The experimental results indicate that 3.0-6.0 wt% of P(BA-AA) is required to obtain stable composite emulsions, and P(BA-AA) with a mass ratio of BA:AA = 1:2 is able to generate distinct core-corona structures. A mechanism of composite particle formation is proposed based on the high affinity between the PSt core and the hydrophobic segments of P(BA-A). The regular morphology of the colloidal film is expected to facilitate potential application of core-corona particles in the field of light scattering. Furthermore, the diversity of core-corona particles can be expanded by replacing P(BA-AA) corona particles with other amphiphilic particles.

  10. 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 P-00...

  11. 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...

  12. 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

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

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

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

  14. Superconductivity in Al-substituted Ba8Si46 clathrates

    NASA Astrophysics Data System (ADS)

    Li, Yang; Garcia, Jose; Chen, Ning; Liu, Lihua; Li, Feng; Wei, Yuping; Bi, Shanli; Cao, Guohui; Feng, Z. S.

    2013-05-01

    There is a great deal of interest vested in the superconductivity of Si clathrate compounds with sp3 network, in which the structure is dominated by strong covalent bonds among silicon atoms, rather than the metallic bonding that is more typical of traditional superconductors. A joint experimental and theoretical investigation of superconductivity in Al-substituted type-I silicon clathrates is reported. Samples of the general formula Ba8Si46-xAlx, with different values of x were prepared. With an increase in the Al composition, the superconducting transition temperature TC was observed to decrease systematically. The resistivity measurement revealed that Ba8Si42Al4 is superconductive with transition temperature at TC = 5.5 K. The magnetic measurements showed that the bulk superconducting Ba8Si42Al4 is a type II superconductor. For x = 6 sample Ba8Si40Al6, the superconducting transition was observed down to TC = 4.7 K which pointed to a strong suppression of superconductivity with increasing Al content as compared with TC = 8 K for Ba8Si46. Suppression of superconductivity can be attributed primarily to a decrease in the density of states at the Fermi level, caused by reduced integrity of the sp3 hybridized networks as well as the lowering of carrier concentration. These results corroborated by first-principles calculations showed that Al substitution results in a large decrease of the electronic density of states at the Fermi level, which also explains the decreased superconducting critical temperature within the BCS framework. The work provided a comprehensive understanding of the doping effect on superconductivity of clathrates.

  15. Hysteretic electrical transport in BaTiO{sub 3}/Ba{sub 1−x}Sr{sub x}TiO{sub 3}/Ge heterostructures

    SciTech Connect

    Ngai, J. H.; Kumah, D. P.; Walker, F. J.; Ahn, C. H.

    2014-02-10

    We present electrical transport measurements of heterostructures comprised of BaTiO{sub 3} and Ba{sub 1−x}Sr{sub x}TiO{sub 3} epitaxially grown on Ge. Sr alloying imparts compressive strain to the BaTiO{sub 3}, which enables the thermal expansion mismatch between BaTiO{sub 3} and Ge to be overcome to achieve c-axis oriented growth. The conduction bands of BaTiO{sub 3} and Ba{sub 1−x}Sr{sub x}TiO{sub 3} are nearly aligned with the conduction band of Ge, which facilitates electron transport. Electrical transport measurements through the dielectric stack exhibit rectifying behavior and hysteresis, where the latter is consistent with ferroelectric switching.

  16. 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.

  17. 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.

  18. 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.

  19. Superconducting EuBa 2Cu 3O 7-δ and YbBa 2Cu 3O 7-δ produced by oxidation of microcrystalline precursor alloys

    NASA Astrophysics Data System (ADS)

    Weiss, F.; Yavari, A. R.; Rouault, A.; Hadar, R.; Senateur, J. P.; Desre, P.

    1988-06-01

    EuBa2Cu3 and YbBa2Cu3 microcrystalltne alloys obtained by rapid solidification have been oxidized completely in flowing oxygen at a temperature higher than 900° C with subsequent slow cooling and have yield the high temperature oxides EuBa2Cu37-δ and YbBa2Cu3O7-δ. The onset of superconductivity occured at 92 K in the case of Eu and at 89 K in the case of Yb. The resistivity in the normal state ( ρ at 100 K) is lower than in sintered powder materials Sue to a better compaction and to a better intergrain coupling.

  20. 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.

  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. Ab initio calculations of BaTiO3 (111) surfaces

    NASA Astrophysics Data System (ADS)

    Eglitis, R. I.

    2013-11-01

    The article presents the results of calculations of polar (111) surface relaxations and energetics using the ab initio code CRYSTAL and a hybrid description of exchange and correlation. Using a hybrid B3LYP approach, the surface relaxation has been calculated for the two possible Ti and BaO3 BaTiO3 (111) surface terminations. For both Ti- and BaO3-terminated BaTiO3 (111) surfaces, the upper layer atoms relax inward. The second layer atoms, with the sole exception of Ti-terminated BaTiO3 (111) surface Ba atom, relax outward. The calculated surface relaxation energy for Ti-terminated BaTiO3 (111) surface is more than two times larger than the surface relaxation energy for BaO3-terminated BaTiO3 (111) surface. The surface energy for Ti-terminated BaTiO3 (111) surface (7.28 eV/cell) is smaller, than the surface energy for BaO3-terminated (111) surface (8.40 eV/cell).

  3. Ionic interactions of Ba2+ blockades in the MthK K+ channel.

    PubMed

    Guo, Rui; Zeng, Weizhong; Cui, Hengjun; Chen, Liping; Ye, Sheng

    2014-08-01

    The movement and interaction of multiple ions passing through in single file underlie various fundamental K(+) channel properties, from the effective conduction of K(+) ions to channel blockade by Ba(2+) ions. In this study, we used single-channel electrophysiology and x-ray crystallography to probe the interactions of Ba(2+) with permeant ions within the ion conduction pathway of the MthK K(+) channel. We found that, as typical of K(+) channels, the MthK channel was blocked by Ba(2+) at the internal side, and the Ba(2+)-blocking effect was enhanced by external K(+). We also obtained crystal structures of the MthK K(+) channel pore in both Ba(2+)-Na(+) and Ba(2+)-K(+) environments. In the Ba(2+)-Na(+) environment, we found that a single Ba(2+) ion remained bound in the selectivity filter, preferably at site 2, whereas in the Ba(2+)-K(+) environment, Ba(2+) ions were predominantly distributed between sites 3 and 4. These ionic configurations are remarkably consistent with the functional studies and identify a molecular basis for Ba(2+) blockade of K(+) channels.

  4. The quasi-binary phase diagram BaF2-BaBr2 and its relation to the x-ray storage phosphor BaFBr : Eu2+

    NASA Astrophysics Data System (ADS)

    Kolb, R.; Schlapp, M.; Hesse, S.; Schmechel, R.; von Seggern, H.; Fasel, C.; Riedel, R.; Ehrenberg, H.; Fuess, H.

    2002-08-01

    In order to understand the formation and stoichiometry of the x-ray storage phosphor BaFBr : Eu2+, the phase diagram of the quasi-binary BaF2-BaBr2 system has been investigated. The phase diagram was obtained by means of differential thermal analysis and temperature controlled x-ray diffraction experiments. The resulting phase diagram indicates that BaFBr forms a compound with no detectable solid solubility for neither BaF2 nor BaBr2. Experiments to obtain non-stoichiometric BaFBr via the synthesis route using BaF2 and NH4Br as proposed in the literature could not be verified. It will be shown that the type of colour centre created during x-ray irradiation is related to the non-stoichiometry of the starting compositions before sintering. A surplus of either barium fluoride or barium bromide during sintering allows the controlled formation of F(Br-)- and F(F-)-centres, respectively.

  5. Unexpected size distribution of Ba(H2O)n clusters: why is the intensity of the Ba(H2O)1 cluster anomalously low?

    PubMed

    Cabanillas-Vidosa, Iván; Rossa, Maximiliano; Pino, Gustavo A; Ferrero, Juan C

    2011-08-07

    An experimental and theoretical study on the reactivity of neutral Ba atoms with water clusters has been conducted to unravel the origin of the irregular intensity pattern observed in one-photon ionization mass spectra of a Ba(H(2)O)(n)/BaOH(H(2)O)(n-1) (n = 1-4) cluster distribution, which was generated in a laser vaporization-supersonic expansion source. The most remarkable irregular feature is the finding for n = 1 of a lower intensity for the Ba(+)(H(2)O)(n) peak with respect to that of BaOH(+)(H(2)O)(n-1), which is opposite to the trend for n = 2-4. Rationalization of the data required consideration of a distinct behavior of ground-state and electronically excited state Ba atoms in inelastic and reactive Ba + (H(2)O)(n) encounters that can occur in the cluster source. Within this picture, the generation of Ba(H(2)O)(n) (n > 1) association products results from stabilizing collisions with atoms of the carrier gas, which are favored by intramolecular vibrational redistribution that operates on the corresponding collision intermediates prior to stabilization; the latter is unlikely to occur for Ba + (H(2)O) encounters. Overall, this interpretation is consistent with additional in-source laser excitation and quenching experiments, which aimed to explore qualitatively the effect of perturbing the Ba atom electronic state population distribution on the observed intensity pattern, as well as with the energetics of various possible reactions for the Ba + H(2)O system that derive from high level ab initio calculations.

  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. BaTMAn: Bayesian Technique for Multi-image Analysis

    NASA Astrophysics Data System (ADS)

    Casado, J.; Ascasibar, Y.; García-Benito, R.; Guidi, G.; Choudhury, O. S.; Bellocchi, E.; Sánchez, S. F.; Díaz, A. I.

    2016-12-01

    Bayesian Technique for Multi-image Analysis (BaTMAn) characterizes any astronomical dataset containing spatial information and performs a tessellation based on the measurements and errors provided as input. The algorithm iteratively merges spatial elements as long as they are statistically consistent with carrying the same information (i.e. identical signal within the errors). The output segmentations successfully adapt to the underlying spatial structure, regardless of its morphology and/or the statistical properties of the noise. BaTMAn identifies (and keeps) all the statistically-significant information contained in the input multi-image (e.g. an IFS datacube). The main aim of the algorithm is to characterize spatially-resolved data prior to their analysis.

  8. Superconductivity in the Graphite Intercalation Compound BaC 6

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    Among many two-dimensional (2D) high TC 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 TC=65 mK . By adding this finding as the additional experimental point, a complete figure displaying the relationship between TC 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.

  9. Superconductivity of BaLi4 under pressure

    NASA Astrophysics Data System (ADS)

    Schaeffer, Anne Marie J.; DeLong, Matthew C.; Anderson, Zachary W.; Talmadge, William B.; Guruswamy, Sivaraman; Deemyad, Shanti

    2013-09-01

    We studied the pressure-induced superconductivity of BaLi4 up to 53 GPa by means of electrical resistivity in a diamond anvil cell. Superconductivity in BaLi4 is first observed at a pressure of 5.4 GPa with a superconducting critical temperature (Tc) of 4.5 K. Below 2 GPa, superconductivity is not observed above the minimum temperature achievable in the current study, 2 K. Between 5.4 and 12 GPa, the Tc increases steeply to its maximum value of 7 K. Above 12 GPa, the pressure dependence of Tc is complex and the sign of dTc/dP changes several times in going up to the maximum pressure studied, of 53 GPa.

  10. Performances of RPCs in the BaBar Experiment

    SciTech Connect

    Messner, Robert

    2003-09-26

    The BaBar experiment uses a big system based on RPC detectors to discriminate muons from pions and to identify neutral hadrons. About 2000 m{sup 2} of RPC chambers have been working at SLAC since the end of 1998. We report on the performances of the RPC chambers focusing on new problems discovered in the RPC behavior. These problems started very soon after the installation of the chambers on the detector when the high ambient temperature triggered an increase of dark currents inside the chambers and a reduction of the efficiency. Careful analysis of the BaBar data and dedicated R&D efforts in the laboratory have helped to identify the main source of the trouble in the linseed oil varnish on the bakelite electrodes.

  11. 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.

  12. Performances of RPCs in the BaBar experiment

    NASA Astrophysics Data System (ADS)

    Anulli, F.; Baldini, R.; Band, H.; Bionta, R.; Brau, J.; Brigljevic, V.; Buzzo, A.; Calcaterra, A.; Carpinelli, M.; Cartaro, T.; Cavallo, N.; Crosetti, G.; De Nardo, G.; De Sangro, R.; Eichenbaum, A.; Falciai, D.; Fabozzi, F.; Ferroni, F.; Finocchiaro, G.; Forti, F.; Frey, R.; Johnson, J.; Gatto, C.; Grauges-Pous, E.; Iwasaki, M.; Lange, D.; Lista, L.; Lo Vetere, M.; Lu, C.; Neal, H.; Neri, N.; Macri, M.; Messener, B.; Monge, M. R.; Moore, T.; Morganti, S.; Palano, A.; Paoloni, E.; Paolucci, P.; Passaggio, S.; Pastore, F.; Patrignani, C.; Patteri, P.; Peruzzi, I.; Piccolo, D.; Piccolo, M.; Piredda, G.; Pompili, A.; Robutti, E.; Roodman, A.; Santroni, A.; Sciacca, C.; Sinev, N.; Soha, A.; Storm, D.; Tosi, S.; Va'vra, J.; Xie, Y.; Wright, D.; Wisniewski, W.

    2003-12-01

    The BaBar experiment uses a big system based on RPC detectors to discriminate muons from pions and to identify neutral hadrons. About 2000 m2 of RPC chambers have been working at SLAC since the end of 1998. We report on the performances of the RPC chambers focusing on new problems discovered in the RPC behaviour. These problems started very soon after the installation of the chambers on the detector when the high-ambient temperature triggered an increase of dark currents inside the chambers and a reduction of the efficiency. Careful analysis of the BaBar data and dedicated R&D efforts in the laboratory have helped to identify the main source of the trouble in the linseed oil varnish on the bakelite electrodes.

  13. Superconductivity in noncentrosymmetric BaAl4 derived structures

    NASA Astrophysics Data System (ADS)

    Kneidinger, F.; Salamakha, L.; Bauer, E.; Zeiringer, I.; Rogl, P.; Blaas-Schenner, C.; Reith, D.; Podloucky, R.

    2014-07-01

    Ternary intermetallics Ep-T-X, crystallizing in ordered variants of the BaAl4 structure type, have been investigated systematically with respect to their formation and stability. For this, a comprehensive overview of the BaAl4 derivative structure types including group-subgroup relations was established. Special emphasis was laid on compounds where inversion symmetry is missing in the respective crystal structures and where superconductivity is observed at low temperatures. EpTX3 compounds crystallize in the noncentrosymmetric BaNiSn3 structure type (space-group I4mm; a ≈0.4 and c ≈1 nm), an ordered ternary derivative of BaAl4. Superconductivity below 3 K was found for seven members of this series, as evidenced from heat capacity and electrical resistivity measurements. Although the Rashba-like spin-orbit coupling in noncentrosymmetric systems can enable a mixture of spin-singlet and spin-triplet pairs in the superconducting condensate, the experimental data basically indicate a predominant s-wave superconducting state in all of these compounds. For this family of compounds, fully relativistic density functional theory (DFT) calculations of the electronic structure and phonon properties were done. Despite the different size of spin-orbit coupling depending on the actual choice of elements for Ep, T, and X that result in different spin-orbit splittings of the Fermi surfaces, the experimental observation of a prevalent spin-singlet pairing in the superconducting phases of the EpTX3 compounds is supported.

  14. Thermoelectric properties of topological insulator BaSn2

    NASA Astrophysics Data System (ADS)

    Guo, San-Dong; Qiu, Liang

    2017-01-01

    Recently, \\text{BaS}{{\\text{n}}2} has been predicted to be a strong topological insulator by the first-principle calculations. It is well known that topological insulators have a close connection to thermoelectric materials, such as the \\text{B}{{\\text{i}}2}\\text{T}{{\\text{e}}3} family. In this work, we investigate thermoelectric properties of \\text{BaS}{{\\text{n}}2} by the first-principles calculations combined with the Boltzmann transport theory. The electronic part is carried out by a modified Becke and Johnson (mBJ) exchange potential, including spin-orbit coupling (SOC), while the phonon part is performed using a generalized gradient approximation (GGA). It was found that the electronic transport coefficients between the in-plane and cross-plane directions showed strong anisotropy, while lattice-lattice thermal conductivities demonstrated almost complete isotropy. Calculated results revealed a very low lattice thermal conductivity for \\text{BaS}{{\\text{n}}2} , and the corresponding average lattice thermal conductivity at room temperature is 1.69 \\text{W}~{{\\text{m}}-1}~{{\\text{K}}-1} , which is comparable or lower than those of lead chalcogenides and bismuth-tellurium systems as classic thermoelectric materials. Due to the complicated scattering mechanism, calculating the scattering time τ is challenging. By using an empirical τ ={{10}-14} s, the n-type figure of merit ZT is greater than 0.40 in wide temperature ranges. Experimentally, it is possible to attain better thermoelectric performance by strain or tuning size parameters. This work indicates that \\text{BaS}{{\\text{n}}2} may be a potential thermoelectric material, which can stimulate further theoretical and experimental work.

  15. 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.

  16. Electronic States of IC60BA and PC71BM

    NASA Astrophysics Data System (ADS)

    Sheng, Chun-Qi; Wang, Peng; Shen, Ying; Li, Wen-Jie; Zhang, Wen-Hua; Zhu, Jun-Fa; Lai, Guo-Qiao; Li, Hong-Nian

    2013-11-01

    We investigate the electronic states of IC60BA and PC71BM using first-principles calculations and photoelectron spectroscopy (PES) measurements. The energy level structures for all possible isomers are reported and compared with those of C60, C70 and PC61BM. The attachment of the side chains can raise the LUMO energies and decrease the HOMO-LUMO gaps, and thus helps to increase the power-conversion efficiency of bulk heterojunction solar cells. In the PES studies, we prepared IC60BA and PC71BM films on Si:H(111) substrates to construct adsorbate/substrate interfaces describable with the integer charge-transfer (ICT) model. Successful measurements then revealed that one of the most important material properties for an electron acceptor, the energy of the negative integer charge-transfer state (EICT-), is 4.31 eV below the vacuum level for PC71BM. The EICT- of IC60BA is smaller than 4.14 eV.

  17. 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.

  18. Analysis of Jupiter’s Oval BA: A streamlined approach

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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 does appear to have increased in strength during this time interval, which 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.

  19. Crystal structure and superconductivity of BaIr₂Ge₇ and Ba₃Ir₄Ge₁₆ with two-dimensional Ba-Ge networks.

    PubMed

    Ishida, Shigeyuki; Yanagi, Yousuke; Oka, Kunihiko; Kataoka, Kunimitsu; Fujihisa, Hiroshi; Kito, Hijiri; Yoshida, Yoshiyuki; Iyo, Akira; Hase, Izumi; Gotoh, Yoshito; Eisaki, Hiroshi

    2014-04-09

    The Ba-Ir-Ge ternary compounds BaIr2Ge7 and Ba3Ir4Ge16 exhibit superconductivity (SC) at 2.5 and 5.2 K, respectively. Detailed single-crystal structural analysis revealed that these compounds share unique quasi-two-dimensional networks composed of crown-shaped Ge rings that accommodate Ba atoms at the center, referred to as "edge-shared crown-shaped BaGe16 polyhedra". The layered Ba-Ge network yielded a modest anisotropy of 1.3-1.4 in the upper critical field, which is in good agreement with the band structure calculations. The Ba-Ge structural unit is similar to cage structures seen in various clathrates in which the anharmonic vibration of the central atoms, the so-called "rattling" behavior, brings about strong-coupling SC. However, each Ba-Ge unit is relatively small compared to these materials, which likely excludes the possibility of unconventional SC.

  20. High-pressure synthesis of the cubic perovskite BaRuO3 and evolution of ferromagnetism in ARuO3 (A = Ca, Sr, Ba) ruthenates

    PubMed Central

    Jin, C.-Q.; Zhou, J.-S.; Goodenough, J. B.; Liu, Q. Q.; Zhao, J. G.; Yang, L. X.; Yu, Y.; Yu, R. C.; Katsura, T.; Shatskiy, A.; Ito, E.

    2008-01-01

    The cubic perovskite BaRuO3 has been synthesized under 18 GPa at 1,000°C. Rietveld refinement indicates that the new compound has a stretched Ru–O bond. The cubic perovskite BaRuO3 remains metallic to 4 K and exhibits a ferromagnetic transition at Tc = 60 K, which is significantly lower than the Tc ≈ 160 K for SrRuO3. The availability of cubic perovskite BaRuO3 not only makes it possible to map out the evolution of magnetism in the whole series of ARuO3 (A = Ca, Sr, Ba) as a function of the ionic size of the A-site rA, but also completes the polytypes of BaRuO3. Extension of the plot of Tc versus rA in perovskites ARuO3 (A = Ca, Sr, Ba) shows that Tc does not increase as the cubic structure is approached, but has a maximum for orthorhombic SrRuO3. Suppressing Tc by Ca and Ba doping in SrRuO3 is distinguished by sharply different magnetic susceptibilities χ(T) of the paramagnetic phase. This distinction has been interpreted in the context of a Griffiths' phase on the (Ca Sr)RuO3 side and bandwidth broadening on the (Sr,Ba)RuO3 side. PMID:18480262

  1. High-resolution laser spectroscopy of BaOH and BaOD: Anomalous spin-orbit coupling in the AΠ state

    NASA Astrophysics Data System (ADS)

    Tandy, J. D.; Wang, J.-G.; Bernath, P. F.

    2009-05-01

    The AΠ(0 0 0)-XΣ+(0 0 0) transition of BaOD has been rotationally analyzed using laser excitation spectroscopy. BaOD molecules were synthesized through the reaction of Ba atoms with D 2O in a Broida-type oven. Rotational and fine structure parameters determined for the AΠ(0 0 0) state of BaOD yielded a spin-orbit coupling constant A significantly different from the corresponding value for BaOH (˜605.8 cm -1 versus 560.1 cm -1). Λ-doubling constants for the AΠ state were observed to be in poor agreement with the predictions of the pure precession model for the interaction between the AΠ and the BΣ+ states in BaOD. Explanations for the unusual spin-orbit splitting and apparent failure of the pure precession and unique perturber models in BaOH and BaOD are discussed, with particular reference to possible global and local perturbations arising from vibrationally excited bands of the AΔ state.

  2. 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.

  3. Structural and chemical characterization of BaTiO{sub 3} nanorods

    SciTech Connect

    Zagar, K.; Recnik, A.; Sturm, S.; Gajovic, A.; Ceh, M.

    2011-03-15

    Research highlights: {yields} Polycrystalline BaTiO{sub 3} nanorods were synthesized with EPD into AAO templates. {yields} Nanorods are composed of crystalline, nanosized grains with pseudo-cubic structure. {yields} Integrowth of hexagonal BaTiO{sub 3} polymorph within pseudo-cubic structure was observed. -- Abstract: An electron-microscopy investigation was performed on BaTiO{sub 3} nanorods that were processed by sol-gel electrophoretic deposition (EPD) into anodic aluminium oxide (AAO) membranes. The BaTiO{sub 3} nanorods grown within the template membranes had diameters ranging from 150 to 200 nm, with an average length of 10-50 {mu}m. By using various electron-microscopy techniques we showed that the processed BaTiO{sub 3} nanorods were homogeneous in their chemical composition. The BaTiO{sub 3} nanorods were always polycrystalline and were composed of well-crystallized, defect-free, pseudo-cubic BaTiO{sub 3} grains, ranging from 10 to 30 nm. No intergranular phases were observed between the BaTiO{sub 3} grains. A low-temperature hexagonal polymorph that is coherently intergrown with the BaTiO{sub 3} perovskite matrix was also observed as a minor phase. When annealing the AAO templates containing the BaTiO{sub 3} sol in an oxygen atmosphere the presence of the hexagonal polymorph was diminished.

  4. Reactions of NO2 with Ba(OH)2 on Pt(111)

    SciTech Connect

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

    2010-10-14

    The interaction of NO2 with amorphous and crystalline Ba(OH)2 supported on Pt(111) was studied in the wide pressure range of 1.0 × 10-9 to 1.0 × 10-4 Torr and compared to that with a thick (> 20 monolayer equivalent (MLE)) BaO film using infrared reflection absorption spectroscopy (IRAS), temperature programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). The amorphous and crystalline Ba(OH)2 layers were prepared by exposing a thick BaO (> 20 MLE) layer on Pt(111) to H2O at 300 and 425 K, respectively. The amorphous and crystalline Ba(OH)2 layers partially convert to Ba(NOx)2 (nitrites and nitrates) following their exposure to elevated NO2 pressure (~1.0 × 10-4 Torr) at 300 K. The exposure of the crystalline-Ba(OH)2/Pt(111) system to NO2 at 425 K, however, leads to the desorption of H2O and the complete conversion of the crystalline Ba(OH)2 layer to Ba(NOx)2, which consists of mainly crystalline nitrates and a small amount of nitrites. The amounts of NOx stored by BaO (> 20 MLE)/Pt(111) and crystalline Ba(OH)2/Pt(111) systems upon their exposure to NO2 at 425 K are comparable. The thus-formed bulk crystalline Ba(NO3)2 phase decomposes in two steps, both releasing NO and O2, in accord with the melting/decomposition scheme for bulk Ba(NO3)2.

  5. Electronic properties of BaCuChF (Ch=S,Se,Te) surfaces and BaCuSeF/ZnPc interfaces

    NASA Astrophysics Data System (ADS)

    Zakutayev, Andriy; Tate, Janet; Platt, Heather A. S.; Keszler, Douglas A.; Hein, Corinna; Mayer, Thomas; Klein, Andreas; Jaegermann, Wolfram

    2010-05-01

    BaCuChF (Ch=S,Se,Te) surfaces and BaCuSeF interfaces with zinc phthalocyanine (ZnPc) were studied by photoelectron spectroscopy. BaCuChF compounds oxidize when exposed to ambient atmosphere. Se capping layers were studied as a means to produce representative surfaces for photoelectron spectroscopic measurements. Decapped BaCuSeF surfaces remain O-free and C-free when the Se layer is evaporated but they become F-deficient. The resulting surfaces have work functions of 4.85 eV and Fermi levels located 0.25 eV above the valence band maximum. In situ stepwise deposition of ZnPc on a BaCuSeF film surface produced a chemically inert interface with a hole-injection barrier of 0.11 eV.

  6. XANES and micro-Raman spectroscopy study of the barium titanosilicates BaTiSi2O7 and BaTiSi4O11

    NASA Astrophysics Data System (ADS)

    Viani, A.; Pollastri, S.; Macova, P.; Palermo, A.; Peréz-Estébanez, M.; Gualtieri, A. F.

    2016-04-01

    The coordination environment around Ti4+ in the photoluminescent compound BaTiSi2O7 and in BaTiSi4O11 was investigated with X-ray absorption near-edge structure spectroscopy and micro-Raman spectroscopy. The presence of VTi in TiO5 pyramidal units with one short Ti-O bond involving the apical oxygen was detected in both compounds. Interpretation of the vibrational signal from the silicate framework suggested that BaTiSi4O11 is a metasilicate containing building units of SiO4 tetrahedra, which are larger than in other barium titanosilicates. These results confirmed the same structural environment of Ti4+ as recently disclosed by structure refinement of BaTiSi2O7 and provided new insights into the unknown structure of BaTiSi4O11 in the light of the study of its physical properties as potential functional material.

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

    SciTech Connect

    Fujiwara, Kohei Nishihara, Kazuki; Shiogai, Junichi; Tsukazaki, Atsushi

    2016-08-15

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

  8. Calculated g -factors of 5 d double perovskites Ba2NaOsO6 and Ba2YOsO6

    NASA Astrophysics Data System (ADS)

    Ahn, Kyo-Hoon; Pajskr, Karel; Lee, Kwan-Woo; Kuneš, Jan

    2017-02-01

    Using Wannier functions to represent the density functional results we calculate the hybridization corrections to the orbital momentum operator in the Os 5 d shell of the Mott insulators Ba2NaOsO6 and Ba2YOsO6 . The g -factors are obtained by evaluating the spin and orbital momentum operators in the atomic ground states of the Os ion. While the hybridization corrections play a minor role in the d3 ion of Ba2YOsO6 with a dominant spin moment, they are instrumental for the observation of the nonzero g -factor of the d1 ions of Ba2NaOsO6 . In addition, we analyze the exchange interactions in Ba2YOsO6 and find them to be consistent with the reported magnetic structure.

  9. 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

  10. 73Ge- and 135/137Ba-NMR Studies of Clathrate Superconductor Ba24Ge100

    NASA Astrophysics Data System (ADS)

    Kanetake, Fumiya; Harada, Atsushi; Mukuda, Hidekazu; Kitaoka, Yoshio; Rachi, Takeshi; Tanigaki, Katsumi; Itoh, Kohei M.; Haller, Eugene E.

    2009-10-01

    We report on the normal-state properties of a superconducting type-III clathrate compound Ba24Ge100 investigated by 73Ge-NMR at cage sites and by 135/137Ba-NMR at guest sites at ambient pressure (P=0) and 2.7 GPa. The measurements of the nuclear spin-lattice relaxation rate 1/T1 have revealed a significant increase in 1/T1T of approximately 200 K at P=0, which may be relevant to the rattling motion of Ba atoms in Ge cages. This increase in 1/T1T at high temperatures is markedly suppressed at P=2.7 GPa. As a result of the suppression of the successive structural transformations, the 1/T1T=const. in a low-temperature regime is increased, proving the increase in the density of states at the Fermi level, N(EF), at P. It is this increase in N(EF) that increases the superconducting transition temperature Tc from 0.24 K at P=0 to 3.8 K at P˜ 2.7 GPa.

  11. Field effect in perovskite heterostructures based on BaSnO3 and BaHfO3

    NASA Astrophysics Data System (ADS)

    Kim, Young Mo; Park, Chulkwon; Kim, Useong; Shin, Juyeon; Kim, Youjung; Char, Kookrin

    Perovskite La-doped BaSnO3 (BLSO) was reported to possess high electron mobility and excellent oxygen stability. We fabricated a field effect transistor on SrTiO3 substrate using BLSO as a channel layer and BaHfO3 (BHO) as a gate insulator. To reduce the threading dislocations and enhance the electrical properties of the channel, undoped BaSnO3 (BSO) buffer layer was grown on SrTiO3 substrates before the channel layer deposition. X-ray diffraction measurement confirms the epitaxial growth of BHO on BSO. We investigated optical and dielectric properties of the BHO gate insulator; the optical bandgap and the dielectric constant were measured to be 6.1 eV and 37.8, respectively. Using BHO as the gate insulator, we obtained the conductivity modulation in the channel by field effect. We will report on the electrical properties of the field effect transistor such as the output characteristics, the transfer characteristics, the Ion/Ioff ratio, the subthreshold swing and the field effect mobility.

  12. 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

  13. Paracoherence studies in Tl 2CaBa 2Cu 2O 8,CaLaBaCu 3O 7-y and CaSmBaCu 3O 7-y

    NASA Astrophysics Data System (ADS)

    Krishnan, H.; Sankaranarayanan, V.; Srinivasan, R.

    1990-08-01

    In ceramic superconductors, where the intergrain coupling is weak, the phase transition at T co corresponds to the temperature at which phase coherence occurs in all the grains. The region between T m, the mid point of the superconducting transition, and T co, the temperature at which the resistivity goes to zero, is called the paracofioerence region. The resistivity behaviour of single phase Tl 2CaBa 2Cu 2O 8, CaLaBaCu 3O 7-y and CaSmBaCu 3O 7-y has been studied in the above region and the results indicate that the excess conductivity varies as (T - T co) -γ.

  14. Enhancement of p-type conductivity in nanocrystalline BaTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Guo, Xin; Pithan, Christian; Ohly, Christian; Jia, Chun-Lin; Dornseiffer, Jügen; Haegel, Franz-Hubert; Waser, Rainer

    2005-02-01

    Undoped BaTiO3 ceramic samples with an average grain size of ˜35nm were prepared and the electrical properties investigated. The defect structure is dominated by acceptor impurities; therefore, the conductivity of nanocrystalline BaTiO3 is of p-type. Comparing with microcrystalline BaTiO3, the conductivity of nanocrystalline BaTiO3 is about 1 to 2 orders of magnitude higher and the activation energy remarkably lower, which is ascribed to a greatly reduced oxidation enthalpy in nanocrystalline BaTiO3 (˜0.3 versus ˜0.92eV for microcrystalline BaTiO3).

  15. 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.

  16. Laser-induced synthesis of BaMoO4 nanocolloidal suspension and its optical properties

    NASA Astrophysics Data System (ADS)

    Ryu, Jeong Ho; Kim, Kang Min; Mhin, Sung Wook; Park, Gyeong Seon; Eun, Jong Won; Shim, Kwang Bo; Lim, Chang Sung

    2008-08-01

    Pulsed laser ablation in a liquid phase was successfully employed to synthesize a barium molybdate (BaMoO4) nanocolloidal suspension. The nanocolloidal suspension was composed of well-dispersed and horizontally assembled BaMoO4 aggregates. The BaMoO4 aggregates showed predominantly elliptically shaped nanorods with sizes between 100 and 200 nm. The preferential elliptical growth was rationalized from the viewpoint of the intrinsic structure of BaMoO4. The optical properties of the prepared BaMoO4 colloidal nanoparticles were investigated using Raman spectroscopy, UV vis spectroscopy and photoluminescence (PL) spectrophotometry. The optical band gap was estimated by Tauc and Menth’s law. The PL emission feature was decomposed into several individual Gaussian components, which could be interpreted by a Jahn Teller splitting effect on the [MoO4]2- tetrahedron of the BaMoO4 colloidal nanoparticles.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  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. Dimension effects on the dielectric properties of fine BaTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Hou, Zhi-Wen; Kang, Ai-Guo; Ma, Wei-Qing; Zhao, Xiao-Long

    2014-11-01

    It is found that the core-shell structured grains are easy to produce for fine grain doped BaTiO3 ceramics in the sintering process. We study the influence of the core-shell structure on the Curie—Weiss temperature and dielectric properties of BaTiO3 ceramics by using effective medium approximation (EMA). Considering the second approximation, the dielectric properties of fine grain doped BaTiO3 ceramics are consistent with experimental data.

  3. Light Sensitive Lattice Defects In BaTiO3 Containing Fe

    NASA Astrophysics Data System (ADS)

    Possenriede, Ewald; Schirmer, Ortwin F.; Godefroy, Genevieve; Maillard, Alain

    1989-01-01

    Electron spin resonance spectra, which can consistently be explained by the models Fe4+ - Vo and Fe5+ - vBa, have been observed with BaTiO3 containing Fe. Also Fe3+ and - Fe3+ - Vo have been identified. All these centers as well as several unidentified ones are observed to change their charge states under illumination. They thus are possibly in involved in photorefractive processes in BaTiO3 containing Fe.

  4. c-Axis tunneling characteristics of Nd-Ba-Cu-O/Pr-Ba-(Cu,Ga)-O/Nd-Ba-Cu-O planar junctions

    NASA Astrophysics Data System (ADS)

    Alvarez, G. A.; Haibara, H.; Iguchi, I.

    2002-02-01

    In order to detect the Josephson plasma excited by the vortices in the flux-flow state, superconducting tunnel junctions fabricated from high quality thin film multilayers, with atomically flat surfaces and interfaces are required. We are investigating planar junctions fabricated from c-axis NBa 2Cu 3O 7- δ/PrBa 2Cu 3- xGa xO 7- δ/NBa 2Cu 3O 7- δ (NBCO/PBCGO/NBCO) quasi-homoepitaxial multilayers. c-Axis tunneling spectroscopy investigations give evidence of quasi-particle tunneling that is commonly observed for superconductor-insulator-superconductor junctions. The influence of the non-equilibrium superconductivity causes significant I-V curve deformation.

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

    PubMed

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

    2014-01-25

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

  6. An Investigation of Insulating La 4BaCu 5O 12 Obtained by the Reduction of Metallic La 4BaCu 5O 13.1

    NASA Astrophysics Data System (ADS)

    Rangavittal, N.; Subbanna, G. N.; Row, T. N. Guru; Rao, C. N. R.

    1995-01-01

    The structure of insulating La 4BaCu 5O 12 obtained by the reduction of metallic La 4BaCu 5O 13.1 has been studied by using electron microscopy and high-resolution X-ray diffraction data. While La 4BaCu 5O 13.1 ( P4/ m) has a tetragonal structure with the supercell a c5 × a c5 × a c, the reduced phase, La 4BaCu 5O 12, is monoclinic ( P2/ m) with the supercell a c5 × a c × a c5. La 4BaCu 5O 12 consists of CuO 5 square pyramids and CuO 4 square planar units, instead of CuO 6 octahedra and CuO 5 square pyramids as in La 4BaCu 5O 13.1. Electron microscopic examination reveals the presence of twinning in some of the crystals of La 4BaCu 5O 12.

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    Yellow LaBa2Ta5O13N2 was successfully synthesized as phase-pure material crystallizing isostructurally to previously reported Ba3Ta5O14N and mixed-valence Ba3TaV4TaIVO15. The electronic structure of LaBa2Ta5O13N2 was studied theoretically with the range-separated hybrid method HSE06. The most stable structure was obtained when lanthanum was placed on 2a and nitrogen on 4h sites confirming Pauling's second rule. By incorporating nitrogen, the measured band gap decreases from ∼3.8 eV for the oxide via 2.74 eV for Ba3Ta5O14N to 2.63 eV for the new oxide nitride, giving rise to an absorption band well in the visible-light region. Calculated fundamental band gaps confirm the experimental trend. The atom-projected density of states has large contributions from N2p orbitals close to the valence band edge. These are responsible for the observed band gap reduction. Photocatalytic hydrogen formation was investigated and compared with that of Ba3Ta5O14N revealing significantly higher activity for LaBa2Ta5O13N2 under UV-light.

  8. Superconducting thin films of Tl 2Ca 2Ba 2Cu 3O y and Tl 2CaBa 2Cu 2O y

    NASA Astrophysics Data System (ADS)

    Ginley, D. S.; Kwak, J. F.; Hellmer, R. P.; Baughman, R. J.; Venturini, E. L.; Mitchell, M. A.; Morosin, B.

    1988-11-01

    We present techniques for preparing unoriented polycrystalline and epitaxial superconducting thin films of the Tl 2CaBa 2Cu 2O y and Tl 2Ca 2Ba 2Cu 3O y phases on a wide variety of substrates. The crucial steps determining the properties of the films are shown to be the air sintering and oxygen annealing following the initial metal deposition by electron beam evaporation under a slight oxygen overpressure. A sintered Tl-Ca-Ba-Cu-O pellet is employed as a source of excess Tl during sintering and annealing of the thin film. The Tl concentration in the final films controls the nature of the intergrain connections. The films are characterized by their structural, chemical, magnetic and transport properties. Zero resistance typically occurs at 97 K for Tl 2CaBa 2Cu 2O and at 106 K for Tl 2Ca 2Ba 2Cu 3O y. Transport critical currents of up to 110 000 A/cm 2 have been obtained at 77 K for unoriented Tl 2CaBa 2Cu 2O y, up to 160 000 A/cm 2 for epitaxial Tl 2Ca 2Ba 2Cu 3O y and up to 240 000 A/cm 2 for unoriented Tl 2Ca 2Cu 3O y films with little field dependence of the critical current observed.

  9. Synthesis of BaTaO2N oxynitride from Ba-rich oxide precursor for construction of visible-light-driven Z-scheme overall water splitting.

    PubMed

    Dong, Beibei; Qi, Yu; Cui, Junyan; Liu, Baodan; Xiong, Fengqiang; Jiang, Xin; Li, Zheng; Xiao, Yejun; Zhang, Fuxiang; Li, Can

    2017-08-15

    Barium tantalum oxynitride (BaTaO2N) with an absorption edge of ca. 660 nm is one of the most promising photocatalysts for solar water splitting, and is usually synthesized by nitriding a mixture of Ba and Ta-containing compounds with a Ba/Ta molar ratio of unity under ammonia flow at high temperature, usually causing a high density of defect sites. Herein, we introduce a novel synthesis method for BaTaO2N (BTON) by employing Ba-rich LiBa4Ta3O12, prepared by a flux method, as a precursor of nitridation. As a comparison, BaTaOx was prepared by conventional solid state reaction and used as the precursor. The as-nitrided samples were correspondingly denoted as BTON-Flux and BTON-SSR. It was found that well-crystallized BTON oxynitride can be similarly obtained by both methods, but the BTON-Flux sample exhibits significantly decreased defect density and enhanced surface area relative to the BTON-SSR sample. As a result of their structural differences, the photocatalytic water splitting performance of the BTON-Flux sample, regardless of the H2-evolving half reaction in the presence of methanol or Z-scheme overall water splitting, is much better than that of BTON-SSR. This study may open up a novel strategy for preparing oxynitride photocatalyst with decreased defect density for the promotion of solar water splitting.

  10. 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.

  11. High critical current density over 1 MA cm-2 at 13 T in BaZrO3 incorporated Ba(Fe,Co)2As2 thin film

    NASA Astrophysics Data System (ADS)

    Lee, Jongmin; Jiang, Jianyi; Kametani, Fumitake; Oh, Myeong Jun; Weiss, Jeremy D.; Collantes, Yesusa; Seo, Sehun; Yoon, Sejun; Tarantini, Chiara; Jo, Youn Jung; Hellstrom, Eric E.; Lee, Sanghan

    2017-08-01

    Achieving high critical current density (J c) under a high magnetic field in Fe based superconductors is indispensable for practical applications. Here we report that high critical current density over 1 MA cm-2 in high field (13 T) can be achieved in BaZrO3 (BZO) incorporated Ba(Fe,Co)2As2 (Co-Ba122) thin film grown on CaF2 substrate using pulsed laser deposition. The magnetization J c of Co-Ba122 thin film incorporated with 2 mol.% BZO reaches 1.3 MA cm-2 (Hǁc, 13 T and 4.2 K), 14 times higher than that of pure Co-Ba122 thin film. Transmission electron microscopy observation revealed that BZO forms nanorods of ˜4 nm in average diameter with mean separation of 10-11 nm which corresponds to a matching field of about 17-20 T. Incorporating BZO in Co-Ba122 thin films led to a strong vortex pinning effect and a significant enhancement of J c because a high density of BZO nanorods could form in the superconducting matrix without significant degradation of T c, and the diameter of BZO nanorods is approximately twice the coherence length of Co-Ba122 (ξ ab(0) ˜ 2.5 nm) which is the optimal size as pinning centers.

  12. 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.

  13. Synthesis and Characterization of Bowl-Like Single-Crystalline BaTiO3 Nanoparticles

    PubMed Central

    2010-01-01

    Novel bowl-like single-crystalline BaTiO3 nanoparticles were synthesized by a simple hydrothermal method using Ba(OH)2·8H2O and TiO2 as precursors. The as-prepared products were characterized by XRD, Raman spectroscopy, SEM and TEM. The results show that the bowl-like BaTiO3 nanoparticles are single-crystalline and have a size about 100–200 nm in diameter. Local piezoresponse force measurements indicate that the BaTiO3 nanoparticles have switchable polarization at room temperature. The local effective piezoelectric coefficient is approximately 28 pm/V. PMID:20596350

  14. 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.

  15. 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.

  16. Magnon-scattering spectra of PrBa2Cu3O6, PrBa2Cu3O7, NdBa2Cu3O6, and Nd1.6Ba1.4Cu3O7.3

    NASA Astrophysics Data System (ADS)

    Yoshida, Masashi; Koshizuka, Naoki; Tanaka, Shoji

    1990-11-01

    Raman-scattering spectra from PrBa2Cu3O6, PrBa2Cu3O7, NdBa2Cu3O6, and Nd1.6Ba1.4Cu3O7.3 single crystals have been measured at room temperature. Magnon-pair-scattering peaks with B1g symmetry have been observed in PrBa2Cu3O6, NdBa2Cu3O6, and Nd1.6Ba1.4Cu3O7.3, and the exchange integrals have been determined as 920, 930, and 950 cm-1, respectively. The exchange integral of the compounds with the Cu-O5 pyramid structure decreases as the Cu-Cu distance increases. On the other hand, it is found that the magnon-pair scattering is suppressed in nonsuperconducting PrBa2Cu3O7, suggesting that holes are not localized on the Pr site, but have a probability to populate the Cu-O plane just as in the superconducting Y-Ba-Cu-O-type compounds.

  17. Low-Temperature Synthesis, Structure, and Stability of Ba 2+ yCu 3O 6

    NASA Astrophysics Data System (ADS)

    Brosha, Eric L.; Garzon, Fernando H.; Raistrick, Ian D.; Davies, Peter K.

    1996-02-01

    Single-phase powders of Ba2Cu3O6have been prepared at 620°C under 1 atm of oxygen using freeze-dried nitrate precursors. Calcinations utilizing a precursor with a 1:1 Ba:Cu stoichiometry produced a two-phase mixture of BaO2+ Ba2Cu3O6and confirmed the stable, oxidized barium cuprate exists with a metal ion ratio close to 2:3. Diffraction studies suggest that Ba2Cu3O6(Ba0.67CuO2) crystallizes in a structure closely related to the linear chain KCuO2and NaCuO2cuprates. It is proposed that the reduction of copper and accompanying loss of oxygen observed above 620°C are accommodated by an increase in the Ba content of the structure and the formation of Ba2+yCu3O6with 0 ≤y≤ 0.25. Above 710°C, the high-yend member is metastable with respect to BaCuO2, although it decomposes slowly even at elevated temperatures.

  18. A teleost complement factor Ba possesses antimicrobial activity and inhibits bacterial infection in fish.

    PubMed

    Li, Xue-Peng; Sun, Li

    2017-01-24

    Complement factor B (Bf) is a component of the complement system. Following activation of the alternative pathway of the complement system, factor B is cleaved into Ba and Bb fragments. In fish, the Bf of rainbow trout is known to act as a C3 convertase, but the function of the Ba fragment is essentially unknown. In this study, we examined the expression patterns of tongue sole Cynoglossus semilaevis Bf (named CsBf) and the biological activity of the Ba fragment of CsBf (named CsBa). CsBf possesses the conserved domains of Bf and shares 39.9%-56.4% sequence identities with other fish Bf. CsBf expression was high in liver, muscle, and heart, and low in intestine, blood, and kidney. Bacterial infection significantly induced CsBf expression in kidney, spleen, and liver in a time-dependent manner. Recombinant CsBa (rCsBa) exhibited apparent binding capacities to bacteria and tongue sole peripheral blood leukocytes, and binding of rCsBa to bacteria inhibited bacterial growth. When overexpressed in tongue sole, CsBa significantly reduced bacterial dissemination in fish tissues. Together these results indicate for the first time that a fish Ba possesses antibacterial effect as well as immune cell-binding capacity, and thus probably plays a role in host immune defense against bacterial infection.

  19. 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.

  20. Structure and stability of BaTiSi₂O₇.

    PubMed

    Viani, Alberto; Palermo, Andrea; Zanardi, Stefano; Demitri, Nicola; Petrícek, Václav; Varini, Federico; Belluso, Elena; Ståhl, Kenny; Gualtieri, Alessandro Francesco

    2015-04-01

    Due to their optical, photo-luminescence (PL), and afterglow properties, barium titanosilicates are compounds of great interest for functional materials and light-emitting devices. Among them, BaTiSi2O7 (BTS2) is certainly one of the most intriguing; it displays peculiar properties (e.g. PL orange emission) whose exhaustive explanation has been hampered to date by the lack of a structure model. In this work, BTS2 and the related compound BaTiSi4O11 (BTS4) were synthesized through conventional solid-state reaction methods. BTS2 invariably shows complex twinning patterns. Thus, its structure solution and Rietveld structure refinement were attempted using synchrotron powder diffraction. BTS2 was found to be an intergrowth of monoclinic and triclinic crystals. The monoclinic phase has the space group P21/n and unit cell a = 7.9836 (3), b = 10.0084 (4), c = 7.4795 (3) Å, and β = 100.321 (3)°, whereas the triclinic phase has the space group P\\bar 1 and unit cell a = 7.99385 (4), b = 10.01017 (5), c = 7.47514 (3) Å, α = 90.084 (8), β = 100.368 (8) and γ = 89.937 (9)°. These lattices can be seen as a distortion of that of tetragonal synthetic β-BaVSi2O7 with Ti in place of V. The structure models obtained from this study confirm the presence of fivefold coordinated Ti atoms in a distorted pyramidal configuration. The proposed solution supports existing theories for the explanation of the PL orange colour in BTS2.

  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. Flux Creep in Sintered Superconducting Y-Ba-Cu-O

    NASA Astrophysics Data System (ADS)

    Matsushita, Teruo; Funaba, Seiji; Nagamatsu, Yoshiyuki; Ni, Baorong; Funaki, Kazuo; Yamafuji, Kaoru

    1989-09-01

    The flux creep rate in sintered superconducting Y-Ba-Cu-O was measured at 77 K and in fields of up to 0.1 T. The pinning potential mainly caused by flux pinning inside grains was 0.25 eV at B{=}50 mT and decreased monotonically with increasing magnetic field. The obtained results can be explained by the theoretical model with observed intragrain current density. This theoretical model suggests that the flux creep at high fields is notable even if a superconducting wire with the critical current density of 2× 1010 A/m2 at B{=}5 T is realized.

  3. Thin film processing of photorefractive BaTiO3

    NASA Technical Reports Server (NTRS)

    Schuster, Paul R.

    1993-01-01

    During the period covered by this report, October 11, 1991 through October 10, 1992, the research has progressed in a number of different areas. The sol-gel technique was initially studied and experimentally evaluated for depositing films of BaTiO3. The difficulties with the precursors and the poor quality of the films deposited lead to the investigation of pulsed laser deposition as an alternative approach. The development of the pulsed laser deposition technique has resulted in continuous improvements to the quality of deposited films of BaTiO3. The initial depositions of BaTiO3 resulted in amorphous films, however, as the pulsed laser deposition technique continued to evolve, films were deposited in the polycrystalline state, then the textured polycrystalline state, and most recently heteroepitaxial films have also been successfully deposited on cubic (100) oriented SrTiO3 substrates. A technique for poling samples at room temperature and in air is also undergoing development with some very preliminary but positive results. The analytical techniques, which include x-ray diffraction, ferroelectric analysis, UV-Vis spectrophotometry, scanning electron microscopy with x-ray compositional analysis, optical and polarized light microscopy, and surface profilometry have been enhanced to allow for more detailed evaluation of the samples. In the area of optical characterization, a pulsed Nd:YAG laser has been incorporated into the experimental configuration. Now data can also be acquired within various temporal domains resulting in more detailed information on the optical response of the samples and on their photorefractive sensitivity. The recent establishment of collaborative efforts with two departments at Johns Hopkins University and the Army Research Lab at Fort Belvoir has also produced preliminary results using the metallo-organic decomposition technique as an alternative method for thin film processing of BaTiO3. RF and DC sputtering is another film deposition

  4. Low-lying Collective States in {sup 136}Ba

    SciTech Connect

    Scheck, M.; Mukhopadhyay, S.; Crider, B.; Choudry, S. N.; Elhami, E.; Peters, E. E.; McEllistrem, M. T.; Orce, J. N.; Yates, S. W.

    2009-01-28

    Low-lying collective states in {sup 136}Ba were investigated with (n,n'{gamma}) techniques, including Doppler-shift attenuation lifetime measurements. The level spins, lifetimes, branching ratios, multipole-mixing ratios and transition strengths reveal candidates for symmetric-phonon states up to third order. The 2{sub ms}{sup +} mixed-symmetry state was confirmed as unfragmented and a candidate for a [2{sub 1}{sup +} x 2{sub ms}{sup +}]{sub 3}{sup +} two-phonon mixed-symmetry state is proposed.

  5. 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.

  6. Design of a minimum emittance nBA lattice

    NASA Astrophysics Data System (ADS)

    Lee, S. Y.

    1998-04-01

    An attempt to design a minimum emittance n-bend achromat (nBA) lattice has been made. One distinct feature is that dipoles with two different lengths were used. As a multiple bend achromat, five bend achromat lattices with six superperiod were designed. The obtained emittace is three times larger than the theoretical minimum. Tunes were chosen to avoid third order resonances. In order to correct first and second order chromaticities, eight family sextupoles were placed. The obtained emittance of five bend achromat lattices is almost equal to the minimum emittance of five bend achromat lattice consisting of dipoles with equal length.

  7. Performance and Aging of the BaBar Drift Chamber

    SciTech Connect

    Kelsey, M

    2003-11-03

    The BaBar Drift Chamber has been operating since May 1999 at the PEP-II B-Factory, integrating a total of 140 fb{sup -1} luminosity in e{sup +}e{sup -} collisions at {radical}s {approx} 10.6 GeV. The chamber has accumulated a dose of approximately 10.6 mC/cm. The performance of the drift chamber with respect to aging (efficiency, gain, resolution) will be presented, along with projections over its expected lifetime.

  8. Syntheses, crystal structures and characterizations of BaZn(SeO{sub 3}){sub 2} and BaZn(TeO{sub 3})Cl{sub 2}

    SciTech Connect

    Jiang Hailong; Feng Meiling; Mao Jianggao . E-mail: mjg@ms.fjirsm.ac.cn

    2006-06-15

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

  9. 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.

  10. Thin films sputtered from Ba{sub 2}NdFeNb{sub 4}O{sub 15} multiferroic targets on BaFe{sub 12}O{sub 19} coated substrates

    SciTech Connect

    Bodeux, Romain; Michau, Dominique; Maglione, Mario; Josse, Michaël

    2016-09-15

    Highlights: • Synthesis of Ba{sub 2}NdFeNb{sub 4}O{sub 15}/BaFe{sub 12}O{sub 19} (BaM) heterostructures by RF magnetron sputtering. • Growth of TTB layer were retained regardless of the underlayer (Pt bottom electrode or BaM). • Dielectric and magnetic properties were obtained from the Pt/TTB/BaM/Pt stacks. - Abstract: Ba{sub 2}NdFeNb{sub 4}O{sub 15} tetragonal tungsten bronze (TTB)/BaFe{sub 12}O{sub 19} (BaM) hexaferrite bilayers have been grown by RF magnetron sputtering on Pt/TiO{sub 2}/SiO{sub 2}/Si (PtS) substrates. The BaM layer is textured along (0 0 1) while the TTB layer is multioriented regardless of the PtS or BaM/PtS substrate. Dielectric properties of TTB films are similar to those of bulk, i.e., ε ∼ 150 and a magnetic hysteresis loop is obtained from TTB/BaM bilayers, thanks to the BaM component. This demonstrates the possibility of transferring to 2 dimensional structures the composite multiferroic system TTB/BaM previously identified in 3 dimensional bulk ceramics.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  12. 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.

  13. [Effect of PEG400 on the luminescent Eu(BA)3/SiO2].

    PubMed

    Zeng, Dong-ming; Li, Yan-hua; Fu, Chang-cheng; Liu, You-nian; Shu, Wan-gen

    2007-02-01

    Rare earth organic complexes combined with inorganic compounds can enhanced thermal stability, but inorganic compounds matrix has great influence on the luminescence characteristic of rare earth organic complexes. The luminescence characteristic of organic and inorganic compound material was improved by PEG doping in the material. Eu(BA)3/SiO2 and Eu(BA)3/PEG400-SiO2 were synthesized by Sol-Gel method. The result of luminescence analysis showed that the excitation spectra and emission spectra of Eu(BA)3 accorded with those of Eu(BA)3/SiO2 and Eu(BA)3/PEG400-SiO2, but the luminescence intensity of Eu(BA)3/SiO2 was improved by PEG400-SiO2 in SiO2 gel. This was because PEG400 as a hard Lewis base, could be combined with rare earth ion and increase the luminescence intensity of Eu(BA)3. It was shown that the amount of PEG400 in Eu(BA)3/SiO2 had influence on luminescence intensity of Eu(BA)3, namely there was better luminescence intensity in Eu(BA)3/SiO2 with increment of the PEG400 addition, but when the amount of PEG400 exceeded 50 wt% of that of SiO2, the luminescence intensity of Eu(BA)3 hardly increased. When the amount of PEG400 exceed 15 wt% of that of SiO2, PEG400 had little influence on the content of water and hydroxy in the matrix, as verified by IR spectrum. The surface characteristic of SiO2 gel was investigated by atomic force microscopy (AFM).

  14. thermodynamics of nitrogen in BaO-TiOx melts

    NASA Astrophysics Data System (ADS)

    Tomioka, Katsutomo; Suito, Hideaki

    1993-02-01

    Using a gas-slag-metal equilibration technique, nitrogen contents in BaO-TiO^ slags and nitrogen and titanium contents in liquid Cu were measured at 1823, 1873, and 1923 K under controlled partial pressures of oxygen (@#@ PO 2 = 10-11.5 ≈ 10-13.7 atm) and nitrogen (@#@ PN 2 = 0.9 atm). The nitride capacity, C(N) [=(mass pct N) · PO2/3/4, (mass pct Ti3+)/(mass pct Ti4+) ratio, and solubility of TiN in BaO-TiO2-TiO1.5 slags were obtained as a function of slag com-position (@#@ XBaO = 0.20 = 0.43) and temperature. Activity coefficients of TiN were estimated, using the values for activity coefficients of Ti in liquid Cu which were calculated from the results of a TiN saturation experiment. Free energy of dissolution of nitrogen into liquid Cu was derived as °GGN o = 32,400 + 46.17 ± 1400 (J/g · atom).

  15. Magnetoelectricity coupled exchange bias in BaMnF4

    PubMed Central

    Zhou, Shuang; Wang, Ji; Chang, Xiaofeng; Wang, Shuangbao; Qian, Bin; Han, Zhida; Xu, Qingyu; Du, Jun; Wang, Peng; Dong, Shuai

    2015-01-01

    Multiferroic BaMnF4 powder was prepared by hydrothermal method. Hysteretic field dependent magnetization curve at 5 K confirms the weak ferromagnetism aroused from the canted antiferromagnetic spins by magnetoelectric coupling. The blocking temperature of 65 K for exchange bias coincides well with the peak at 65 K in the zero-field cooled temperature-dependent magnetization curve, which has been assigned to the onset temperature of two-dimensional antiferromagnetism. An upturn kink of exchange field and coercivity with decreasing temperature was observed from 40 K to 20 K, which is consistent with the two-dimensional to three-dimensional antiferromagnetic transition at Néel temperature (~26 K). In contrast to the conventional mechanism of magnetization pinned by interfacial exchange coupling in multiphases, the exchange bias in BaMnF4 is argued to be a bulk effect in single phase, due to the magnetization pinned by the polarization through magnetoelectric coupling. PMID:26671575

  16. Aging Studies of 2nd Generation BaBar RPCs

    SciTech Connect

    Band, H.R.; /SLAC

    2007-09-25

    The BaBar detector, operating at the PEPII B factory of the Stanford Linear Accelerator Center (SLAC), installed over 200 2nd generation Resistive Plate Chambers (RPCs) in 2002. The streamer rates produced by backgrounds and signals from normal BaBar running vary considerably (0.1- >20 Hz/cm2) depending on the layer and position of the chambers, thus providing a broad spectrum test of RPC performance and aging. The lowest rate chambers have performed very well with stable efficiencies averaging 95%. Other chambers had rate-dependant inefficiencies due to Bakelite drying which were reversed by the introduction of humidified gases. RPC inefficiencies in the highest rate regions of the higher rate chambers have been observed and also found to be rate dependant. The inefficient regions grow with time and have not yet been reduced by operation with humidified input gas. Three of these chambers were converted to avalanche mode operation and display significantly improved efficiencies. The rate of production of HF in the RPC exhaust gases was measured in avalanche and streamer mode RPCs and found to be comparable despite the lower current of the avalanche mode RPCs.

  17. DIRC - The Particle Identification System for BaBar

    SciTech Connect

    Leith, David

    2002-08-19

    I have the pleasure of reporting on the status of the DIRC particle identification sub-system(2) of the BaBar Detector, running at the asymmetric B Factory at SLAC. The acronym DIRC stands for ''Detection of Internally Reflected Cherenkov Light.'' This device grows out of our group's experience with ring-imaging Cherenkov devices founded on a long partnership with Tom Ypsilantis and in particular with the CRID device for the SLD experiment. Blair Ratcliff had the brilliant idea of using the totally internally reflected Cherenkov light created in quartz bars, and transported out to the photon detectors by those same quartz bars, to provide excellent {pi}, K, p particle identification in the momentum range important for the B Factory. His naming of this new instrument was aptly ''CRID'' spelled backwards. The detailed design, building and commissioning of the DIRC sub-system was the work of a large international collaboration of French and U.S. groups. The device has proven to be a very robust detector, with the promised performance essentially fully realized, and is being effectively utilized in almost all of the current BaBar physics analysis.

  18. 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.

  19. Towards a sub 15-dBA optical micromachined microphone.

    PubMed

    Kim, Donghwan; Hall, Neal A

    2014-05-01

    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.

  20. Mid-IR Atmospheric Tracers of Jupiter's Storm Oval BA

    NASA Astrophysics Data System (ADS)

    Shannon, Matthew J.; Orton, G.; Fletcher, L.

    2010-10-01

    The 2005-2006 reddening of a major anticyclonic storm, known as Oval BA, in Jupiter's turbulent atmosphere may well be a paradigm for the formation of red-colored vortices on the giant planets, including Jupiters Great Red Spot. Mid-infrared observations can be effectively used to determine physical and chemical properties of the atmosphere, and we present the results of mid-infrared thermal imaging observations, collected from NASAs Infrared Telescope Facility (IRTF) in Hawaii, ESOs Very Large Telescope (VLT) in Chile and the NAOJ Subaru Telescope in Hawaii between spring of 2005 and summer of 2006. These address the role of atmospheric tracers, including cloud opacity, the ammonia gas content, and the variation of the fraction of para- to ortho-hydrogen from local thermal equilibrium in assessing the rate of upwelling. These properties were retrieved with the Oxford-developed code, Nemesis, with the purpose of providing constraints on dynamical models in an effort to identify the mechanism for the color change. The most obvious change is that the temperature gradient from the inner to the outer part of Oval BA increased over the time of the color change, indicating a strengthening of the intensity of the vortex.

  1. 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.

  2. 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.

  3. 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

  4. Hybrid HF-DFT modeling of monolayer water adsorption on (001) surface of cubic BaHfO 3 and BaZrO 3 crystals

    NASA Astrophysics Data System (ADS)

    Bandura, A. V.; Evarestov, R. A.; Kuruch, D. D.

    2010-09-01

    First-principles calculations have been used to study the atomic structure, preferred sites and adsorption energies for water adsorption at different terminations of the cubic phase of perovskite-structured BaHfO 3 and BaZrO 3. By considering different initial positions of water molecules, the possibility of water dissociation has been investigated. It is demonstrated that the site selectivity and the form of adsorbed molecule can be affected by the choice of surface unit cell. Dissociative adsorption was found to be favorable for all surfaces in consideration. Hydroxylation of ZrO 2- and HfO 2-terminated surfaces is accomplished by a noticeable reconstruction of the surface structure of cubic phase towards the orthorhombic phase. Calculated atomic charges in bare and hydroxylated surfaces show that BaHfO 3 crystal is slightly more ionic than BaZrO 3.

  5. 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.

  6. Is BaCr2As2 symmetrical to BaFe2As2 with respect to half 3d shell filling?

    DOE PAGES

    Richard, P.; van Roekeghem, A.; Lv, B. Q.; ...

    2017-05-25

    We have performed an angle-resolved photoemission spectroscopy study of BaCr2As2, which has the same crystal structure as BaFe2As2, a parent compound BaFe2As2 of Fe-based superconductors. We determine the Fermi surface of this material and its band dispersion down to 5 eV below the Fermi level. Very moderate band renormalization (1.35) is observed for only two bands. We attribute this small renormalization to enhanced direct exchange as compared to Fe in BaFe2As2, and to a larger contribution of the eg orbitals in the composition of the bands forming the Fermi surface.

  7. Novel behaviour and structure of new glasses of the type Ba-Al-O and Ba-Al-Ti-O produced by aerodynamic levitation and laser heating.

    PubMed

    Skinner, L B; Barnes, A C; Crichton, W

    2006-08-16

    Novel barium aluminate (BaAl(2)O(4)) and barium alumino-titanate (BaAl(2)TiO(6)) glasses have been produced by aerodynamic levitation and laser heating. BaAl(2)O(4) forms a clear and colourless glass under containerless and rapid quenching conditions. Under similar rapid quenching conditions BaAl(2)TiO(6) forms an opaque and black glass, while under slower and controlled quenching conditions it is possible to form a clear and colourless glass. The formation of the opaque or clear glass is reversible and purely dependent on the quench rate used. By slowing the quench rate further, it is possible to produce a milky glass suggestive of liquid-liquid phase separation in the liquid before glassification. High-energy x-ray diffraction experiments confirm the glassy state of these materials and show coordination structures and bond distances similar to their crystalline analogues.

  8. BA3b and BA1 activate in a serial fashion after median nerve stimulation: direct evidence from combining source analysis of evoked fields and cytoarchitectonic probabilistic maps.

    PubMed

    Papadelis, Christos; Eickhoff, Simon B; Zilles, Karl; Ioannides, Andreas A

    2011-01-01

    This study combines source analysis imaging data for early somatosensory processing and the probabilistic cytoarchitectonic maps (PCMs). Human somatosensory evoked fields (SEFs) were recorded by stimulating left and right median nerves. Filtering the recorded responses in different frequency ranges identified the most responsive frequency band. The short-latency averaged SEFs were analyzed using a single equivalent current dipole (ECD) model and magnetic field tomography (MFT). The identified foci of activity were superimposed with PCMs. Two major components of opposite polarity were prominent around 21 and 31 ms. A weak component around 25 ms was also identified. For the most responsive frequency band (50-150 Hz) ECD and MFT revealed one focal source at the contralateral Brodmann area 3b (BA3b) at the peak of N20. The component ~25 ms was localised in Brodmann area 1 (BA1) in 50-150 Hz. By using ECD, focal generators around 28-30 ms located initially in BA3b and 2 ms later to BA1. MFT also revealed two focal sources - one in BA3b and one in BA1 for these latencies. Our results provide direct evidence that the earliest cortical response after median nerve stimulation is generated within the contralateral BA3b. BA1 activation few milliseconds later indicates a serial mode of somatosensory processing within cytoarchitectonic SI subdivisions. Analysis of non-invasive magnetoencephalography (MEG) data and the use of PCMs allow unambiguous and quantitative (probabilistic) interpretation of cytoarchitectonic identity of activated areas following median nerve stimulation, even with the simple ECD model, but only when the model fits the data extremely well. Copyright © 2010 Elsevier Inc. All rights reserved.

  9. Normal mode coordinates of high T c superconductors TlCaBa 2Cu 2O 7 and Tl 2CaBa 2Cu 2O 8

    NASA Astrophysics Data System (ADS)

    Mori, T.; Nakaoka, K.; Onari, S.; Arai, T.

    1989-10-01

    Normal mode coordinates of high Tc superconductors TlCaBa 2Cu 2O 7- (Tl-1122) and Tl 2CaBa 2Cu 2O 8(Tl-2122) are analyzed by the shell model calculations. The model calculations have reproduced very well the observed Raman frequencies. The vibrational frequencies of the oxygens on the CuO 2 layers are found to depend on the ionic charges of the oxygens on the CuO 2 layers.

  10. 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.

  11. 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.

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

    PubMed

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

    2008-09-16

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

  13. 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.

  14. 49 CFR 178.51 - Specification 4BA welded or brazed steel cylinders.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 4BA welded or brazed steel cylinders... FOR PACKAGINGS Specifications for Cylinders § 178.51 Specification 4BA welded or brazed steel...) Cylindrical type cylinders must be of circumferentially welded or brazed construction. (b) Steel. The...

  15. 49 CFR 178.51 - Specification 4BA welded or brazed steel cylinders.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specification 4BA welded or brazed steel cylinders... FOR PACKAGINGS Specifications for Cylinders § 178.51 Specification 4BA welded or brazed steel...) Cylindrical type cylinders must be of circumferentially welded or brazed construction. (b) Steel. The...

  16. 49 CFR 178.51 - Specification 4BA welded or brazed steel cylinders.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 4BA welded or brazed steel cylinders... FOR PACKAGINGS Specifications for Cylinders § 178.51 Specification 4BA welded or brazed steel...) Cylindrical type cylinders must be of circumferentially welded or brazed construction. (b) Steel. The...

  17. Facile microwave synthesis and photocatalytic activity of monodispersed BaTiO{sub 3} nanocuboids

    SciTech Connect

    Chen, Pei; Zhang, Yantao; Zhao, Fengqi; Gao, Hongxu; Chen, Xinbing; An, Zhongwei

    2016-04-15

    A facile microwave hydrothermal method for preparation of monodispersed barium titanate (BaTiO{sub 3}) nanocuboids with average size of 13 nm is developed, and the effects of synthesis parameters, such as molar composition of the precursor, synthesis time and temperature, on the morphology of BaTiO{sub 3} nanocrystals are systematically evaluated. The resulting products are characterized by X-ray diffraction (XRD), Raman spectrum, infrared spectrum (IR), UV–vis diffuse reflectance spectrum, water contact angle, thermogravimetry (TG), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and selected area electron diffraction (SAED). A possible formation mechanism of BaTiO{sub 3} nanocuboids is proposed. The BaTiO{sub 3} nanocuboids show high photocatalytic activity for the degradation of Rhodamin B under UV irradiation. - Highlights: • Monodispersed BaTiO{sub 3} nanocuboids are prepared by a facile microwave process. • The BaTiO{sub 3} nanocuboids have average size of 13 nm. • Oleic acid is the key factor to control the morphology of BaTiO{sub 3} nanocuboids. • BaTiO{sub 3} nanocuboids exhibit enhanced photocatalytic properties.

  18. 17 CFR 240.15Ba1-7 - Registration of successor to municipal advisor.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Registration of successor to municipal advisor. 240.15Ba1-7 Section 240.15Ba1-7 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules...

  19. 17 CFR 240.15Ba1-4 - Withdrawal from municipal advisor registration.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Withdrawal from municipal advisor registration. 240.15Ba1-4 Section 240.15Ba1-4 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules...

  20. Ba/Ca coral-based proxy of tropical hydrology: Yucatan Peninsula case study

    NASA Astrophysics Data System (ADS)

    Gonneea, M. E.; Cohen, A. L.; Charette, M. A.

    2011-12-01

    The barium/calcium ratio (Ba/Ca) in corals growing on fringing reefs of the Yucatan Peninsula is a potentially powerful tool with which to reconstruct seasonally resolved, multicentury-long records of precipitation (both seasonally-forced as well as episodic events). The Yucatan Peninsula is a carbonate platform with minimal surface flow, thus groundwater is the major vector for freshwater transport to the coast. The basic premise for this work is that elements enriched in groundwater (such as Ba) are delivered via submarine groundwater discharge (SGD) to the coastal waters of the Yucatan Peninsula and that the magnitude of SGD is positively correlated with precipitation. Delivery of Ba enriched groundwater elevates coastal Ba concentrations and high/low rainfall events are recorded as high/low Ba/Ca ratios in the coral skeleton. Recent quantification of groundwater discharge to coastal waters of the Yucatan Peninsula showed that discharge was three times higher at the end of the wet season relative to the dry season. This strongly suggests that precipitation drives the delivery of fresh groundwater to coastal waters (and the reef). The Ba/Ca ratio of seawater is linearly dependent on salinity, thus this is an excellent tracer of terrestrially source fresh water. Initial Ba/Ca data generated from two corals (Siderastrea spp.) collected live on the Yucatan reefs demonstrate a positive correlation with rainfall; both corals record Hurricane Isadore as a substantial Ba/Ca spike in the 2002 annual growth band.

  1. Band gap tuning of lead-substituted BaSnO3 for visible light photocatalysis

    NASA Astrophysics Data System (ADS)

    Borse, Pramod H.; Joshi, Upendra A.; Ji, Sang Min; Jang, Jum Suk; Lee, Jae Sung; Jeong, Euh Duck; Kim, Hyun Gyu

    2007-01-01

    The Pb substitution effect was investigated experimentally and theoretically on the crystal structure of BaSnO3 and on the photo-oxidation activity of H2O. The chemically doped Pb in BaSnO3 induced a concentration-dependent redshift of the experimental band gap (BG). The BaPb0.8Sn0.2O3 system produced 32μmol /h of O2 under λ ⩾420nm photons, but no O2 for BaSnO3. The DFT calculations of BaPbxSn1-xO3 (x =0,0.5,1) by using generalized approximation, implying the BG alteration and the photocatalytic activity of BaPbxSn1-xO3, are due to the induced Pb 6s orbital in the BG of BaSnO3. Thus Pb modified the insulating nature of BaSnO3 to semiconducting and semimetallic.

  2. First-principles study on the electronic properties of BaCu 2S 2

    NASA Astrophysics Data System (ADS)

    Liu, G. B.; Wang, X. Q.; Kuang, X. J.; L. He, A.

    2010-11-01

    Using the pseudopotential plane-wave method under the density functional theory (DFT), the electronic properties of BaCu 2S 2 in α and β phases are calculated. The result shows that the bottom conduction band is mainly made of Ba 5d state, while the upper valence band is formed by S 3p and Cu 4d states, but both of them for β-BaCu 2S 2 are wider than those for α-BaCu 2S 2. The electron and hole effective masses for BaCu 2S 2 are also analyzed in detail. It is found that β-BaCu 2S 2 has very small hole effective masses, which implies that β-BaCu 2S 2 may possess a high hole mobility. Moreover, its hole effective masses are extremely anisotropic along ab plane and c axis. These properties are helpful to enhance its Seebeck coefficient, and means that β-BaCu 2S 2 could be a good candidate of thermoelectric materials.

  3. Thermal conductivity of BaPuO 3 at temperatures from 300 to 1500 K

    NASA Astrophysics Data System (ADS)

    Tanaka, Kosuke; Sato, Isamu; Hirosawa, Takashi; Kurosaki, Ken; Muta, Hiroaki; Yamanaka, Shinsuke

    2011-07-01

    Polycrystalline specimens of barium plutonate, BaPuO 3, have been prepared by mixing the appropriate amounts of PuO 2 and BaCO 3 followed by reacting and sintering at 1600 K under the flowing gas atmosphere of dry-air. The sintered specimens had a single phase of orthorhombic perovskite structure and were crack-free. The Debye temperature of BaPuO 3 was determined from the sound velocity and lattice parameter measurements. The elastic moduli were also determined from the longitudinal and shear sound velocity. The thermal conductivity of BaPuO 3 was calculated from the measured density at room temperature, literature values of heat capacity, and thermal diffusivity measured by a laser flash method in vacuum. The thermal conductivity of BaPuO 3 was roughly independent of the temperature and was almost the same magnitude as that of BaUO 3. This was markedly lower than the conductivities of other perovskite type oxides and was about one-tenth that of UO 2 around room temperature. The temperature dependence of the thermal conductivity of BaPuO 3 was found to be quite similar to that of BaUO 3.

  4. 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.

  5. 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."

  6. High-k perovskite gate oxide BaHfO3

    NASA Astrophysics Data System (ADS)

    Kim, Young Mo; Park, Chulkwon; Ha, Taewoo; Kim, Useong; Kim, Namwook; Shin, Juyeon; Kim, Youjung; Yu, Jaejun; Kim, Jae Hoon; Char, Kookrin

    2017-01-01

    We have investigated epitaxial BaHfO3 as a high-k perovskite dielectric. From x-ray diffraction measurement, we confirmed the epitaxial growth of BaHfO3 on BaSnO3 and MgO. We measured optical and dielectric properties of the BaHfO3 gate insulator; the optical bandgap, the dielectric constant, and the breakdown field. Furthermore, we fabricated a perovskite heterostructure field effect transistor using epitaxial BaHfO3 as a gate insulator and La-doped BaSnO3 as a channel layer on SrTiO3 substrate. To reduce the threading dislocations and enhance the electrical properties of the channel, an undoped BaSnO3 buffer layer was grown on SrTiO3 substrates before the channel layer deposition. The device exhibited a field effect mobility value of 52.7 cm2 V-1 s-1, a Ion/Ioff ratio higher than 107, and a subthreshold swing value of 0.80 V dec-1. We compare the device performances with those of other field effect transistors based on BaSnO3 channels and different gate oxides.

  7. 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.

  8. Single crystalline BaTiO3 thin films synthesized using ion implantation induced layer transfer

    NASA Astrophysics Data System (ADS)

    Park, Young-Bae; Diest, Kenneth; Atwater, Harry A.

    2007-10-01

    Layer transfer of BaTiO3 thin films onto silicon-based substrates has been investigated. Hydrogen and helium ions were co-implanted to facilitate ion-implantation-induced layer transfer of films from BaTiO3 single crystals. From thermodynamic equilibrium calculations, we suggest that the dominant species during cavity nucleation and growth are H2, H+, H2O, Ba2+ and Ba-OH, and that the addition of hydrogen to the Ba-Ti-O system can effectively suppress volatile oxide formation during layer transfer and subsequent annealing. After ion implantation, BaTiO3 layers contain microstructural defects and hydrogen precipitates in the lattice, but after layer transfer, the single crystal is found to be stoichiometric. Using direct wafer bonding and layer splitting, single crystal BaTiO3 thin films were transferred onto amorphous Si3N4 and Pt substrates. Micro-Raman spectroscopy indicated that the density of defects generated by ion implantation in BaTiO3 can be significantly reduced during post-transfer annealing, returning the transferred layer to its single crystal state. Characterization using piezoresponse force microscopy shows that the layer transferred thin films are ferroelectric, with domain structures and piezoresponse characteristics similar to that of bulk crystals.

  9. 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.

  10. Spectroscopy, polarization and nonadiabatic dynamics of electronically excited Ba(Ar)n clusters: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Krylov, A. I.; Gerber, R. B.; Gaveau, M. A.; Mestdagh, J. M.; Schilling, B.; Visticot, J. P.

    1996-03-01

    Molecular Dynamics simulations using a surface-hopping method for transitions between different electronic states are employed to study the dynamics following photoexcitation of the Ba(Ar)125 cluster. The results are used to interpret spectroscopic experiments on large, size-distributed Ba(Ar)n clusters. The dynamics of the coupled electronic-nuclear motions in the cluster involves transitions between three potential energy surfaces, corresponding to the nearly-degenerate p-states of the excited Ba atom. Ejection of excited Ba atoms, adsorbed on the surface of the cluster, can take place. The focus in comparing theory and experiment is on the emission spectrum from the excited clusters, on the polarization of this radiation, and on the polarization of light emitted by excited Ba atoms ejected from the cluster. Based on the good agreement found between theory and experiment, a comprehensive picture of the excited state dynamics is given. It is found that upon excitation, energy is rapidly redistributed in the cluster and no direct ejection of Ba occurs. Electronic relaxation to the lowest P-state occurs, and the latter dominates the cluster emission spectrum and polarization. The electronic state relaxation is mostly complete within t≲10 ps. Ejection of Ba atoms occurs as a rare and delayed event when a dynamical fluctuation creates a ``hot spot'' at the Ba site, with a non-adiabatic excitation to the highest electronic level. The results show the feasibility of near-quantitative understanding of non-adiabatic processes in large clusters.

  11. 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…

  12. 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…

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

    PubMed

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

    2015-11-07

    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.

  14. 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.

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

    DTIC Science & Technology

    2017-07-07

    TEXTILES FOR REMEDIATION OF INTERMICROBE ACTIVITY ( BaCTeRIA ) SUMMARY REPORT by Tobyn A. Branck Courtney M. Cowell Jennifer M. Rego and...October 2011 – September 2015 4. TITLE AND SUBTITLE BACTERICIDAL COATINGS ON TEXTILES FOR REMEDIATION OF INTERMICROBE ACTIVITY ( BaCTeRIA ) SUMMARY REPORT...ANTHRAX PURIFICATION BACILLUS ANTHRACIS ENVIRONMENTAL ISOLATES BACTERIA BACTERIOCINS TARGETED ACTIVITY

  16. Understanding Ferromagnetic Phase Stability, Electronic and Transport Properties of BaPaO3 and BaNpO3 from Ab-Initio Calculations

    NASA Astrophysics Data System (ADS)

    Khandy, Shakeel Ahmad; Gupta, Dinesh C.

    2017-10-01

    An extensive study of rare-earth perovskite BaPaO3 and BaNpO3 has been performed by first-principles tactics based on density functional theory (DFT), because the delocalized f-electrons play an important role in the band structure formation, to reveal their impact on the overall physical and chemical properties; it has turned out to be an interesting theme. Along with critical radii and thermoelectric properties, two different theories are employed to calculate the structural properties. The DFT and empirically calculated lattice constants are in rational accord with the experimental results. The critical radius calculations show that the BaPaO3 lattice has a smaller oxygen migration activation energy than the BaNpO3. In addition, we discuss the band profile and magnetic moments for these materials, which demonstrate the half-metallic ferromagnetism with a direct energy gap of 3.91 eV for BaPaO3 and an indirect gap of 3.79 eV for BaNpO3. More interestingly, the integral magnetic moments are in accordance with the Slater-Pauling rule.

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

    DOE PAGES

    Wu, S. F.; Richard, P.; van Roekeghem, A.; ...

    2015-06-08

    In this study, 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 ofmore » 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. In conclusion, our results confirm the prediction that BaCu2As2 is an sp metal with weak electronic correlations.« less

  18. Crystal Structures at Atomic Resolution of the Perovskite-Related GdBaMnFeO5 and Its Oxidized GdBaMnFeO6.

    PubMed

    García-Martín, Susana; Manabe, Keisuke; Urones-Garrote, Esteban; Ávila-Brande, David; Ichikawa, Noriya; Shimakawa, Yuichi

    2017-02-06

    Perovskite-related GdBaMnFeO5 and the corresponding oxidized phase GdBaMnFeO6, with long-range layered-type ordering of the Ba and Gd atoms have been synthesized. Oxidation retains the cation ordering but drives a modulation of the crystal structure associated with the incorporation of the oxygen atoms between the Gd layers. Oxidation of GdBaMnFeO5 increases the oxidation state of Mn from 2+ to 4+, while the oxidation state of Fe remains 3+. Determination of the crystal structure of both GdBaMnFeO5 and GdBaMnFeO6 is carried out at atomic resolution by means of a combination of advanced transmission electron microscopy techniques. Crystal structure refinements from synchrotron X-ray diffraction data support the structural models proposed from the TEM data. The oxidation states of the Mn and Fe atoms are evaluated by means of EELS and Mössbauer spectroscopy, which also reveals the different magnetic behavior of these oxides.

  19. 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.; Etemad, S.; Inam, A.; Venkatesan, T.; Martens, J.S.; Lee, W.Y.; Bourne, L.C.

    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.

  20. New insights into the application of the valence rules in Zintl phases—Crystal and electronic structures of Ba{sub 7}Ga{sub 4}P{sub 9}, Ba{sub 7}Ga{sub 4}As{sub 9}, Ba{sub 7}Al{sub 4}Sb{sub 9}, Ba{sub 6}CaAl{sub 4}Sb{sub 9}, and Ba{sub 6}CaGa{sub 4}Sb{sub 9}

    SciTech Connect

    He, Hua; Stoyko, Stanislav; Bobev, Svilen

    2016-04-15

    Crystals of three new ternary pnictides—Ba{sub 7}Al{sub 4}Sb{sub 9}, Ba{sub 7}Ga{sub 4}P{sub 9}, and Ba{sub 7}Ga{sub 4}As{sub 9} 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 Ba{sub 7}Ga{sub 4}Sb{sub 9}-type structure (space group Pmmn, Pearson symbol oP40, Z=2), for which only the prototype is known. The structure is based on TrPn{sub 4} tetrahedra (Tr=Al, Ga; Pn=P, As, Sb), connected in an intricate scheme into 1D-ribbons. Long interchain Pn–Pn bonds (d{sub P–P}>3.0 Å; d{sub As–As}>3.1 Å; d{sub Sb–Sb}>3.3 Å) account for the realization of 2D-layers, separated by Ba{sup 2+} cations. Applying the classic valance rules to rationalize the bonding apparently fails, and Ba{sub 7}Ga{sub 4}Sb{sub 9} 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 Ba{sub 6}CaTr{sub 4}Sb{sub 9} (Tr=Al, Ga). Single-crystal X-ray diffraction work confirms Ba{sub 6.145(3)}Ca{sub 0.855}Al{sub 4}Sb{sub 9} and Ba{sub 6.235(3)}Ca{sub 0.765}Ga{sub 4}Sb{sub 9}, 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 Ba{sub 7}Ga{sub 4}As{sub 9} is interrogated by tight-binding linear muffin-tin orbital calculations. - Graphical abstract: The new Zintl phases—Ba{sub 7}Al{sub 4}Sb{sub 9}, Ba{sub 7}Ga{sub 4}P{sub 9}, and Ba{sub 7}Ga{sub 4}As{sub 9}, and their quaternary variants Ba{sub 6}CaTr{sub 4}Sb{sub 9} (Tr=Al, Ga)—crystallize in the Ba{sub 7}Ga{sub 4}Sb{sub 9} structure type. The structures are based

  1. Electron-relaxation-mode interaction in BaTiO3:Nb

    NASA Astrophysics Data System (ADS)

    Maglione, M.; Belkaoumi, M.

    1992-02-01

    Dielectric relaxation was previously reported in BaTiO3 and BaTiO3:Fe single crystals at radio frequencies [M. Maglione et al., Phys. Rev. B 40, 11 441 (1989)]. We have measured the dielectric dispersion in four BaTiO3:Nb samples (xNb<0.3 at. %) as a function of frequency (10BaTiO3:Nb enhances drastically the relaxation step at all temperatures. In the rhombohedral phase of BaTiO3:Nb (T<180 K), an unusual slowing down of the relaxation motion is measured. The relaxation time increases to more than 10-2 s at 20 K while the relaxation step is temperature independent. The precursor effect of this slowing down is a maximum in the dc conductivity. A simple electron-relaxation-mode coupling model may explain such behavior.

  2. Nanocrystalline BaTiO3 powder via ambient conditions sol process (Prop.2001-071)

    SciTech Connect

    Payzant, E Andrew; Wang, X.; Hu, Michael Z.; Blom, Douglas Allen

    2005-01-01

    Nanocrystalline BaTiO{sub 3} particles have been prepared by ambient condition sol (ACS) process starting from soluble precursors of barium and titanium yielding a mixed oxide/hydroxide gel. The gel was peptized and crystallized in water under a refluxing condition. Higher initial pH and Ba/Ti ratio led to smaller crystallite sizes of BaTiO{sub 3} powders. Organic mineralizer, tetramethylammonium hydroxide (TMAH), can adsorb on the BaTiO{sub 3} nuclei and inhibited further growth of the particles. Adding a polymer during BaTiO{sub 3} synthesis led to a smaller particle size and increased redispersibility of the particles in water.

  3. BaSnO3 perovskite nanoparticles for high efficiency dye-sensitized solar cells.

    PubMed

    Kim, Dong Wook; Shin, Seong Sik; Lee, Sangwook; Cho, In Sun; Kim, Dong Hoe; Lee, Chan Woo; Jung, Hyun Suk; Hong, Kug Sun

    2013-03-01

    The synthesis of highly crystalline perovskite BaSnO3 nanoparticles for use as photoanode materials in dye-sensitized solar cells (DSSCs) is reported, and the photovoltaic properties of DSSCs based on BaSnO3 nanoparticles (BaSnO3 cells) are demonstrated. The resulting DSSCs exhibit remarkably rapid charge collection and a DSSC fabricated with a BaSnO3 film thickness of 43 µm leads to a high energy conversion efficiency of 5.2 %, which is one of the highest reported for ternary oxide-based DSSCs. More importantly, the BaSnO3 cells show superior charge collection in nanoparticle films compared to TiO2 cells and could offer a breakthrough in the efficiencies of DSSCs.

  4. Thermoelectric transport properties of BaBiTe3-based materials

    NASA Astrophysics Data System (ADS)

    Zhou, Yiming; Zhao, Li-Dong

    2017-05-01

    BaBiTe3, a material with low thermal conductivity, is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. We choose two types of dopants, K and La, trying to optimize its electrical transport properties. The minority carriers, which harm the Seebeck coefficient in this system, are suppressed by La doping. With the increase of both electrical conductivity and Seebeck coefficient, the power factor of 3% La doped BaBiTe3 reaches 3.7 μW cm-1 K-2 which increased by 40% from undoped BaBiTe3. Besides high power factor, the thermal conductivity is also reduced in it. Eventually, a high ZT value, 0.25 at 473 K, for n-type BaBiTe3 is achieved in 3% La doped BaBiTe3.

  5. Structure of Periodic Crystals and Quasicrystals in Ultrathin Films of Ba-Ti-O.

    PubMed

    Cockayne, Eric; Mihalkovič, Marek; Henley, Christopher L

    2016-01-01

    We model the remarkable thin-film Ba-Ti-O structures formed by heat treatment of an initial perovskite BaTiO3 thin film on a Pt(111) surface. All structures contain a rumpled Ti-O network with all Ti threefold coordinated with O, and with Ba occupying the larger. mainly Ti7O7, pores. The quasicrystal structue is a simple decoration of three types of tiles: square, triangle and 30° rhombus, with edge lengths 6.85 Å, joined edge-to-edge in a quasicrystalline pattern; observed periodic crystals in ultrathin film Ba-Ti-O are built from these and other tiles. Simulated STM images reproduce the patterns seen experimentally, and identify the bright protrusions as Ba atoms. The models are consistent with all experimental observations.

  6. The Ba813 chromosomal DNA sequence effectively traces the whole Bacillus anthracis community.

    PubMed

    Ramisse, V; Patra, G; Vaissaire, J; Mock, M

    1999-08-01

    Plasmid genes that are responsible for virulence of Bacillus anthracis are important targets for the DNA-based detection of anthrax. We evaluated the distribution of the Ba813 chromosomal DNA sequence (Ba813) within closely related Bacillus species. Ba813 was systematically identified from 47 strains or isolates of B. anthracis tested, thus indicating its reliability as a tracer for that species. From the 60 strains of closely related Bacillus spp. examined, three bona fide B. cereus and one bona fide B. thuringiensis were found to harbour Ba813. This marker was also detected in Bacillus sp. isolates that were present at high levels in soil samples collected in a place where an anthrax outbreak had occurred. The significance and the possible function of the Ba813 locus is discussed.

  7. Structural, optical and electrical properties of GdAlO3:Eu3+Ba2+

    NASA Astrophysics Data System (ADS)

    Selvalakshmi, T.; Tamilarasi, S.; Bose, A. Chandra

    2015-06-01

    Effect of Ba2+ ions concentration on the photoluminescence of GdAlO3:Eu3+ Ba2+ phosphor is investigated. The phosphors are synthesized by citrate-based sol-gel method and the formation of orthorhombic phase GdAlO3 is confirmed by XRD analysis. Kubelka-Munk function is used to estimate the band gap and the value varies with concentration of Ba2+ is observed. Photoluminescence spectra show a strong red emission peak at 616 nm corresponding to5D0→7F2 transition and its intensity increase with the addition of Ba2+ ions. The presence of Eu3+ and Ba2+ ions in GdAlO3 strongly influences the dielectric property of GdAlO3.

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

    NASA Astrophysics Data System (ADS)

    Moroshkin, P.; Kono, K.

    2016-05-01

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

  9. 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.

  10. La 6BaYCu 8O 20: A New Oxygen Deficient Perovskite

    NASA Astrophysics Data System (ADS)

    Cava, R. J.; Zandbergen, H. W.; Van Dover, R. B.; Krajewski, J. J.; Siegrist, T.; Peck, W. F.; Roth, R. S.; Felder, R. J.

    1994-04-01

    La 6BaYCu 8O 20 is a new three-dimensional oxygen deficient perovskite related to the well-known three-dimensional material La 4BaCu 5O 13. The inclusion of a small rare earth results in an extension of the layerlike areas within the three-dimensional network. The same structure is also found for La 6BaDyCu 8O 20. The structure can be doped with Sr for La, or Ca for the small lanthanide. No superconductivity is observed down to 0.3 K. La 4BaCu 5O 13 and the new compound form the first two members of a new three-dimensional homologous series La 4+2 nBa LnnCu 5+3 nO 13+7 n through the addition of "123" type structural units.

  11. Structure of periodic crystals and quasicrystals in ultrathin films of Ba-Ti-O

    DOE PAGES

    Cockayne, Eric; Mihalkovič, Marek; Henley, Christopher L.

    2016-01-07

    Here, we model the remarkable thin-film Ba-Ti-O structures formed by heat treatment of an initial perovskite BaTiO3 thin film on a Pt(111) surface. All structures contain a rumpled Ti-O network with all Ti threefold coordinated with O, and with Ba occupying the larger. mainly Ti7O7, pores. The quasicrystal structue is a simple decoration of three types of tiles: square, triangle and 30° rhombus, with edge lengths 6.85 Å, joined edge-to-edge in a quasicrystalline pattern; observed periodic crystals in ultrathin film Ba-Ti-O are built from these and other tiles. Simulated STM images reproduce the patterns seen experimentally, and identify the brightmore » protrusions as Ba atoms. The models are consistent with all experimental observations.« less

  12. Structure of periodic crystals and quasicrystals in ultrathin films of Ba-Ti-O

    SciTech Connect

    Cockayne, Eric; Mihalkovič, Marek; Henley, Christopher L.

    2016-01-07

    Here, we model the remarkable thin-film Ba-Ti-O structures formed by heat treatment of an initial perovskite BaTiO3 thin film on a Pt(111) surface. All structures contain a rumpled Ti-O network with all Ti threefold coordinated with O, and with Ba occupying the larger. mainly Ti7O7, pores. The quasicrystal structue is a simple decoration of three types of tiles: square, triangle and 30° rhombus, with edge lengths 6.85 Å, joined edge-to-edge in a quasicrystalline pattern; observed periodic crystals in ultrathin film Ba-Ti-O are built from these and other tiles. Simulated STM images reproduce the patterns seen experimentally, and identify the bright protrusions as Ba atoms. The models are consistent with all experimental observations.

  13. 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.

  14. 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.

  15. Dual preparation of hydrophobic and hydrophilic BaWO{sub 4}:Eu phosphors

    SciTech Connect

    Cho, Young-Sik; Huh, Young-Duk

    2016-06-15

    Highlights: • Red-emitting BaWO{sub 4}:Eu phosphors were prepared in hexane-water bilayer system. • The hydrophobic nanometer-sized BaWO{sub 4}:Eu phosphors were obtained in hexane. • The hydrophilic micrometer-sized BaWO{sub 4}:Eu dendrites were obtained in water. - Abstract: BaWO{sub 4}:Eu phosphors were prepared by performing a solvothermal reaction in a water–hexane bilayer system. A barium oleate (and europium oleate) complex was obtained in hexane via a phase transfer reaction involving Ba{sup 2+} (and Eu{sup 3+}) ions in an aqueous solution of sodium oleate. The outer surfaces of the nanometer-sized BaWO{sub 4}:Eu phosphors were capped by the long alkyl chain of oleate; therefore, the hydrophobic nanometer-sized BaWO{sub 4}:Eu phosphors preferentially dissolved in the hexane layer. The micrometer-sized BaWO{sub 4}:Eu phosphors were obtained in the water layer. The BaWO{sub 4}:Eu phosphors prepared in hexane and water yielded sharp strong absorption and emission peaks at 464 and 615 nm, respectively, due to the {sup 7}F{sub 0} → {sup 5}D{sub 2} and the {sup 5}D{sub 0} →{sup 7} F{sub 2} transitions of the Eu{sup 3+} ions. The BaWO{sub 4}:Eu phosphors are good candidate red-emitting phosphors for use in InGaN blue-emitting diodes, which have an emission wavelength of 465 nm.

  16. 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.

  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. 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.

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

    NASA Astrophysics Data System (ADS)

    Schwarz, Michael; Wendorff, Marco; Röhr, Caroline

    2012-12-01

    The title compounds Ba3ZnHg10 and BaZn0.6Hg3.4 were synthesized from stoichiometric ratios of the elements in Ta crucibles. Their crystal structures, which both represent new structure types, have been determined using single crystal X-ray data. The structure of Ba3ZnHg10 (orthorhombic, oP28, space group Pmmn, a=701.2(3), b=1706.9(8), c=627.3(3)pm, Z=2, R1=0.0657) contains folded 44 Hg nets, where the meshes form the bases of flat rectangular pyramids resembling the structure of BaAl4. The flat pyramids are connected via Hg-Zn/Hg bonds, leaving large channels at the folds, in which Ba(1) and Hg(2) atoms alternate. Whereas the remaining Hg/Zn atoms form a covalent 3D network of three- to five-bonded atoms with short M-M distances (273-301 pm; CN 9-11), the Hg(2) atoms in the channels adopt a comparatively large coordination number of 12 and increased distances (317-348 pm) to their Zn/Hg neighbours. In the structure of BaZn0.6Hg3.4 (cubic, cI320, space group I4bar3d, a=2025.50(7) pm, Z=64, R1=0.0440), with a chemical composition not much different from that of Ba3ZnHg10, the Zn/Hg atoms of the mixed positions M(1/2) are arranged in an slightly distorted primitive cubic lattice with a 4×4×4 subcell relation to the unit cell. The 24 of the originating 64 cubes contain planar cis tetramers Hg(5,6)4 with Hg in a nearly trigonal planar or tetrahedral coordination. In another 24 of the small cubes, two opposing faces are decorated by Hg(3,4)2 dumbbells, two by Ba(2) atoms respectively. The third type of small cubes are centered by Ba(1) atoms only. The complex 3D polyanionic Hg/Zn network thus formed is compared with the Hg partial structure in Rb3Hg20 applying a group-subgroup relation. Despite their different overall structures, the connectivity of the negatively charged Hg atoms, the rather metallic Zn bonding characteristic (as obtained from FP-LAPW band structure calculations) and the coordination number of 16 for all Ba cations relate the two title compounds.

  20. Radiation Monitoring with Diamond Sensors in BaBar

    SciTech Connect

    Edwards, A

    2004-07-13

    In order to safeguard the silicon vertex tracker in the BaBar detector from excessive radiation damage, cumulative dose and instantaneous dose rates are continuously monitored. As an upgrade to the current radiation monitoring system which uses silicon PIN-diodes, we are examining the possible use of single-crystal and/or polycrystalline chemical vapor deposition (CVD) diamonds. The radiation responses of several CVD diamonds have been tested on time scales from tens of nanoseconds to thousands of seconds in order to determine their integrity in monitoring accumulated dose and their response to large sudden changes in dose rates. Two polycrystalline CVD diamonds have been installed near the silicon vertex tracker near existing silicon PIN-diodes for comparative studies. CVD diamond radiation sensors have also been tested using {sup 60}Co and in various magnetic field configurations.

  1. Recent BaBar Results on Hadron Spectroscopy

    SciTech Connect

    Robutti, E.; /INFN, Genoa

    2005-08-29

    Recent results from on hadronic spectroscopy are presented, based on data collected by the BaBar experiment between 1999 and 2004. The properties of the recently discovered D*{sub sJ}(2317){sup +} and D{sub sJ}(2460){sup +} states are studied: resonance parameters and ratios of decay rates are measured from continuum e{sup +}e{sup -} production, and production rates are measured from B decays. A search for the D*{sub sJ}(2632){sup +} state whose observation has been recently reported by the SELEX Collaboration, and a search for a charged partner of the charmonium-like X(3872) state, are performed, yielding negative results. Finally, extensive searches for several pentaquark candidates, both fully inclusive and in B decays, result in no positive evidence.

  2. The Ba II [lambda]4554 resonance line and solar granulation

    NASA Astrophysics Data System (ADS)

    Olshevsky, V. L.; Shchukina, N. G.

    We present the results of an investigation of the impact of NLTE effects and of granulation inhomogeneities on the solar Ba II [lambda]4554 Å line. Our analysis is based on both the classical one-dimensional (1D) solar atmosphere models and on the new generation of three-dimensional (3D) hydrodynamical models. We show that NLTE and 3D effects have to be taken into account for reliable diagnostics of the solar atmosphere using this line. We analyse the influence of different parameters on the line shape. It turns out to be most sensitive to collisional broadening and barium abundance. Uncertainties in the oscillator strength, micro- and macroturbulence (in 1D-case) have a secondary importance. We have derived the barium abundance assuming NLTE. We find ABa = 2.16 in good agreement with the recent result of Asplund et al. (2005).

  3. Electrocaloric effect in BaTiO3 thin films

    NASA Astrophysics Data System (ADS)

    Cao, Hai-Xia; Li, Zhen-Ya

    2009-11-01

    The modified transverse Ising model taking into account the four-spin exchange interaction and quantum fluctuation, as well as the mechanical constraint of the substrate, is constructed and applied to investigate the electrocaloric effect (ECE) in BaTiO3 thin films. It is found that the temperature dependence of ECE strongly depends on both the four-spin exchange interaction and quantum fluctuation. Most importantly, we achieve the adiabatic temperature change ΔT =11.78 K at Tm=490 K, which can be comparable with that observed experimentally in PbZr0.95Ti0.05O3 thin films and ferroelectric polymers. Furthermore, the internal stresses resulting from the clamping effect of the substrate play a crucial role in the ECE of ferroelectric films. Control of the misfit stress by appropriate choice of substrate provides an effective means to improve the adiabatic temperature change for use in cooling or thermodielectric power conversion devices.

  4. 17 CFR 240.15Ba1-2 - Registration of municipal advisors and information regarding certain natural persons.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Affiliated Securities Associations § 240.15Ba1-2 Registration of municipal advisors and information regarding... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Registration of municipal advisors and information regarding certain natural persons. 240.15Ba1-2 Section 240.15Ba1-2 Commodity...

  5. Draft genome sequence of Bacillus pumilus BA06, a producer of alkaline serine protease with leather-dehairing function.

    PubMed

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

    2012-12-01

    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.

  6. Organogenic responses of Pinus pinea cotyledons to hormonal treatments: BA metabolism and cytokinin content.

    PubMed

    Moncaleán, P; Alonso, P; Centeno, M L; Cortizo, M; Rodríguez, A; Fernández, B; Ordás, R J

    2005-01-01

    Isolated cotyledons from mature Pinus pinea L. embryos were cultured in vitro in a factorial combination of 4.4, 10 and 44.4 microM N6-benzyladenine (BA) for 2, 4, 8, 16 and 35 days to optimize shoot regeneration. Incubation of explants in 44.4 microM BA for 4 days, in place of the standard incubation in 4.4 microM BA for 35 days, reduced the entire culture period to 4 weeks. Shortening the culture period had no significant effect on the caulogenic response or the number of buds formed per cotyledon. To establish the relationship between key moments in the caulogenic process induced by 4.4 microM BA and the endogenous concentrations of the active forms of BA and other isoprenoid-type cytokinins (CKs), we examined uptake, metabolism and amount of BA, as well as the amounts of zeatin, dihydrozeatin and their ribosides in P. pinea cotyledons after 1, 2, 6, 12 and 24 h, and 2, 4, 8, 16 and 35 days of exposure to 8-[14C]BA. Uptake and release of BA were associated with water movement between explants and the medium during the first 8 days of culture. The interconvertible forms of BA were the main metabolites formed in the tissues. Inactivation of BA as a result of conjugation or oxidation was insignificant. The endogenous concentration of BA + N6-benzyladenosine was 20-fold higher than the exogenously applied BA during the competence acquisition phase (Days 0-3). The concentration of isoprenoid-type CKs also increased 16-fold and then decreased during this time. Induction of shoot buds (Days 4-8) was characterized by a second peak of BA uptake by explants that triggered the synthesis of N6-benzyladenosine-5 -monophosphate and by the maintenance of isoprenoid-type CKs. Reestablishment of CK homeostasis marked the shift from the induction phase to the shoot development phase in this organogenic process (Days 8-12).

  7. 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

  8. 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.

  9. Manganese Vanadate Chemistry in Hydrothermal BaF 2 Brines: Ba 3 Mn 2 (V 2 O 7 ) 2 F 2 and Ba 7 Mn 8 O 2 (VO 4 ) 2 F 23

    DOE PAGES

    Sanjeewa, Liurukara D.; McMillen, Colin D.; McGuire, Michael A.; ...

    2016-12-05

    We synthesized manganese vanadate fluorides using high-temperature hydrothermal techniques with BaF2 as a mineralizer. Ba3Mn2(V2O7)2F2 crystallizes in space group C2/c and consists of dimers built from edge-sharing MnO4F2 trigonal prisms with linking V2O7 groups. Ba7Mn8O2(VO4)2F23 crystallizes in space group Cmmm, with a manganese oxyfluoride network built from edge- and corner-sharing Mn2+/3+(O,F)6 octahedra. The resulting octahedra form alternating Mn2+ and Mn2+/3+ layers separated by VO4 tetrahedra. This latter compound exhibits a canted antiferromagnetic order below TN = 25 K.

  10. 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.

  11. Crystal chemical and quantum chemical studies of Ba(Sr)-Nb oxide compounds

    NASA Technical Reports Server (NTRS)

    Zubkov, V. G.; Turzhevsky, S. A.; Pereliaev, V. A.; Liechtenstein, A. I.; Gubanov, V. A.

    1990-01-01

    The information available on the BaO(SrO)-NbO-NbO2 system with the niobium atom in the lower oxidation degree is very limited. Very few compounds have been found previously in this system. They are BaNbO3, SrxNbO3(0,7=x=1), Ba2Nb2O9, SrNb8O14; and some suggestions on the BaNb8O14 existence have been made also. At the same time Nb-based oxide compounds could be quite interesting in the search of new noncopper high T(sub c) superconductors Researchers studied Ba(Sr) NbxO2x-2 and Ba2(Sr2)-NbxO2x-1 compositions in the phase diagram of BaO(SrO)-NbO-NbO2 system. The synthesis of the materials was carried out in vacuum at the temperatures of 1000 to 1500 C. Barium carbonate and niobium pentoxide were used as initial components. X-ray analysis was carried out.

  12. 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.

  13. Crystal structure of a Ba(2+)-bound gating ring reveals elementary steps in RCK domain activation.

    PubMed

    Smith, Frank J; Pau, Victor P T; Cingolani, Gino; Rothberg, Brad S

    2012-12-05

    RCK domains control activity of a variety of K(+) channels and transporters through binding of cytoplasmic ligands. To gain insight toward mechanisms of RCK domain activation, we solved the structure of the RCK domain from the Ca(2+)-gated K(+) channel, MthK, bound with Ba(2+), at 3.1 Å resolution. The Ba(2+)-bound RCK domain was assembled as an octameric gating ring, as observed in structures of the full-length MthK channel, and shows Ba(2+) bound at several positions. One of the Ba(2+) sites, termed C1, overlaps with a known Ca(2+)-activation site, determined by residues D184 and E210. Functionally, Ba(2+) can activate reconstituted MthK channels as observed in electrophysiological recordings, whereas Mg(2+) (up to 100 mM) was ineffective. Ba(2+) activation was abolished by the mutation D184N, suggesting that Ba(2+) activates primarily through the C1 site. Our results suggest a working hypothesis for a sequence of ligand-dependent conformational changes that may underlie RCK domain activation and channel gating. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. [Establishment of BA-ELISA method for detecting CEA in human sera].

    PubMed

    Yang, Jing; Zeng, Zhao-wei; Wang, Xue-qian; Zhao, Qian; Sun, Hui; Li, Hui-qiang

    2012-08-01

    To establish a sensitive biotin-avidin enzyme linked immunosorbent assay (BA-ELISA) method for detecting carcinoembryonic antigen (CEA) in serum. CEA which had been purified by affinity chromatography was used to immunize the rabbits to produce polyclonal antibodies. Then the antibodies were connected with biotin and horseradish peroxidase (HRP). So BA-ELISA method was established on the basis of 96 microwell plates coated with biotinylated BSA. Finally we examined the sensitivity, specificity, stability and recovery rate of this system and compared the BA-ELISA method with the traditional ELISA, radioimmunoassay and chemiluminescence in detecting CEA concentrations. The stability of this system was proved good. The linear range was from 0.42 to 50 U/mL, the sensitivity was 0.42 U/mL, and the intra-differences together with inter-differences were less than 10.0%. There was significant difference between BA-ELISA and traditional ELISA, while there was no significant difference between BA-ELISA and radioimmunoassay. The regression equation of this method was y=0.04825+0.99674x and r=0.994, and there was no significant difference between the BA-ELISA and chemiluminescence. The BA-ELISA method we established to detect CEA was easy to operate, highly sensitive, low in price and suitable for application in clinical detection.

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

    PubMed

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

    2010-10-01

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

  16. Hemostatic effects of recombinant DisBa-01, a disintegrin from Bothrops alternatus.

    PubMed

    Kauskot, Alexandre; Cominetti, Marcia R; Ramos, Oscar H P; Bechyne, Iga; Renard, Jean-Marie; Hoylaerts, Marc F; Crepin, Michel; Legrand, Chantal; Selistre-de-Araujo, Heloisa S; Bonnefoy, Arnaud

    2008-05-01

    A monomeric RGD-disintegrin was recently identified from a cDNA library from the venom gland of Bothrops alternatus. The corresponding 12 kDa-recombinant protein, DisBa-01, specifically interacted with alpha(v)beta3 integrin and displayed potent anti-metastatic and anti-angiogenic properties. Here, the interaction of DisBa-01 with platelet alphaIIb beta3 integrin and its effects on hemostasis and thrombosis were investigated. DisBa-01 bound to Chinese Hamster Ovary (CHO) cells expressing beta3 or alphaIIb beta3 and promoted their adhesion and the adhesion of resting platelets onto glass coverslips. The disintegrin inhibited the binding of FITC-fibrinogen and FITC-PAC-1 to ADP-stimulated platelets and inhibited ADP-, TRAP- and collagen-induced aggregation of murine, rabbit or human platelets. In a flow chamber assay, DisBa-01 inhibited and reverted platelet adhesion to immobilized fibrinogen. DisBa-01 inhibited the phosphorylation of FAK following platelet activation. The intravenous injection of DisBa-01 in C57Bl6/j mice, prolonged tail bleeding time as well as thrombotic occlusion time in mesenteric venules and arterioles following vessel injury with FeCl3. In conclusion, DisBa-01 antagonizes the platelet alphaIIb beta3 integrin and potently inhibits thrombosis.

  17. 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

  18. 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.

  19. 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.

  20. Materials Chemistry of BaFe2As2: A Model Platform for Unconventional Superconductivity

    SciTech Connect

    Mandrus, David; Safa-Sefat, Athena; McGuire, Michael A; Sales, Brian C

    2010-01-01

    BaFe{sub 2}As{sub 2} is the parent compound of a family of unconventional superconductors with critical temperatures approaching 40 K. BaFe{sub 2}As{sub 2} is structurally simple, available as high-quality large crystals, can be both hole and electron doped, and is amenable to first-principles electronic structure calculations. BaFe{sub 2}As{sub 2} has a rich and flexible materials chemistry that makes it an ideal model platform for the study of unconventional superconductivity. The key properties of this family of materials are briefly reviewed.

  1. Vibrational spectra of (BaF2)n (n=1-6) clusters

    NASA Astrophysics Data System (ADS)

    Pandey, Ratnesh K.; Waters, Kevin; Nigam, Sandeep; Pandey, Ravindra; Pandey, Avinash C.

    2016-05-01

    The vibrational properties of alkaline-earth metal fluoride clusters (BaF2)n (n=1-6) are investigated in the framework of density functional theory. The calculated Raman and Infrared (IR) spectra reveals shift in Raman and IR peak position towards lower frequency region with the increase in the cluster size. Further the calculated spectra have been compared with the experimental vibrational spectra of bulk BaF2 crystal. Even though the smaller size cluster lacks translational symmetry, the structural and vibrational characteristic of (BaF2)5-6 are nearer to bulk counterpart.

  2. Magnetic Properties of New Filled Skutterudite Compound BaFe4As12

    NASA Astrophysics Data System (ADS)

    Sekine, Chihiro; Ishizaka, Takuma; Nishine, Kohei; Kawamura, Yukihiro; Hayashi, Junichi; Takeda, Keiki; Gotou, Hirotada; Hiroi, Zenji

    The magnetic, electrical and thermal properties of a new As-based alkaline-earth-filled skutterudite compound BaFe4As12 prepared under high pressure have been studied at low temperatures. The temperature dependence of the electrical resistivity for BaFe4As12 reveals a metallic behavior. Any anomalies accompanied by phase transition were not observed down to 2K. A broad maximum of magnetic susceptibility around 50 K and a large electronic specific heat coefficient of 62 mJ/molK2 suggest that BaFe4As12 is a nearly ferromagnetic metal with spin fluctuations of Fe 3d electrons.

  3. Structural, morphological and Raman studies on hybridized PVDF/BaTiO3 nanocomposites

    NASA Astrophysics Data System (ADS)

    Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.

    2017-05-01

    Hybridized nanocomposites of polyvinylidene fluoride (PVDF) and nano - barium titanate (BaTiO3) were prepared using the solution casting method for different concentrations of nano-BaTiO3 and were characterized by X-ray diffraction and scanning electron microscopy. The flower like structure for morphology was observed in SEM. Raman analysis showed that the modified BaTiO3 particles, due to higher specific surfaces, induce, predominantly, the crystallization of the electrically active β-phase of PVDF, while the initial micron size particles induce the formation of the most common but non-polar α-crystal form.

  4. Direct writing of three-dimensional woodpile BaTiO3 structures

    NASA Astrophysics Data System (ADS)

    Li, Jijiao; Li, Bo; Wu, Hongya; Zhou, Ji

    2014-05-01

    Barium titanate (BaTiO3) woodpile structures with designed, three-dimensional (3D) geometry have been fabricated by direct-writing assembly techniques. Concentrated BaTiO3 inks with suitable rheological properties were prepared to enable the fabrication of the complex 3D structures. It was demonstrated that BaTiO3 inks with a total solids volume fraction of 0.41 are shear thinning and have a high storage modulus 1 × 105Pa with a yield stress of 300 Pa. Additionally, the woodpile lattice structures exhibited an excellent self-supporting feature.

  5. Electron Diffraction Studies of Superconductors of the K-Ba System and Related Oxides

    NASA Astrophysics Data System (ADS)

    Nikolaichik, V. I.; Klinkova, L. A.

    The application of transmission electron microscopy in combination with physical-chemical methods has made it possible to discover a large number of discrete oxides of ordered structures in the Ba-Bi-O system, which is the parent system for the K-Ba-Bi-O superconducting system. Cation-ordered superconductors Ba1-xKxBiO3 with the crystalline structure of a non-cubic and layered nature have been synthesized. This result removes the crystallographic contradiction between bismuthate and cuprate superconductors that provides support to the existence of a common non-magnetic pairing mechanism.

  6. 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.

  7. 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.

  8. Climate, productivity, and intermediate water nutrients: new records from bamboo coral Ba/Ca

    NASA Astrophysics Data System (ADS)

    Lavigne, M.; Hill, T. M.; Spero, H. J.; Guilderson, T. P.

    2010-12-01

    A geochemical nutrient proxy from deep-sea corals would provide decadal to centennial scale records of intermediate-water nutrient dynamics. Such records could be used to determine how intermediate water masses (300-2000m) are affected by decadal scale climate change (e.g. Pacific Decadal Oscillation) via carbon cycling, export production, and intermediate water-mass circulation/ventilation. Because seawater barium (BaSW ) has a nutrient-like distribution in the water-column (similar to silicate), Ba/Ca records have been used to trace upwelled nutrient supply in shallow water surface corals isolated from terrestrial barium sources. Here we show the first calibration of a nutrient proxy from skeletal barium preserved in the calcitic internodes of bamboo corals. Our calibration was calculated from a depth transect (500-2000m) of Isidella and Keratoisis corals spanning a silicate and (BaSW ) gradient on the California Margin (Ba/Ca coral (µmol/mol) = 0.117 BaSW (nmol/kg ) + 0.835; R2 = 0.88; n = 29). The strong linear correlation between Ba/Ca coral and BaSW suggests that coral Ba/Ca is a reliable recorder of seawater barium (and, therefore, silicate). We find a distribution coefficient (DBa) for bamboo coral Ba/Ca of 1.3±0.1, similar to that of other corals (surface and deep-sea dwelling) and inorganic calcium carbonate precipitation experiments (DBa = 1.2-1.5). This implies that, as true for other carbonates, Ba incorporation is primarily driven by ionic substitution and holds promise as a globally applicable nutrient proxy in bamboo corals. High-resolution Ba/Ca timeseries records sampled via LA-ICP-MS in two co-located California Margin corals (Pioneer Seamount; 830m; 37°22’27”N) co-vary with ~decadal-scale variations in silicate and nitrate measured at 500m depth (CalCOFI line 80 sta. 60; 34°8’60”N). This suggests that high-resolution records of bamboo coral Ba/Ca can be used to reconstruct broad changes in intermediate water nutrients driven by

  9. First-principles calculations of low coverage growth of Ba on Si(001)

    NASA Astrophysics Data System (ADS)

    Ashman, C. R.; Foerst, C. J.; Bloechl, P. E.

    2007-03-01

    Ba is of interest to the semiconductor industry for it's possible use in replacement gate oxide materials and for possible use in a buffer layer between Si(001) and Ba containing dielectric materials. Thus it is of importance to understand the initial stages of growth. This paper reports state-of-the-art electronic structure calculations on the deposition of Barium on the technologically relevant, (001) orientated silicon surface. We identify the surface reconstructions from zero to one monolayer and relate them to previous theoretical studies of low coverage Ba growth and Sr growth.

  10. Ferroelectric control of magnetism in BaTiO3/Fe heterostructures via interface strain coupling

    NASA Astrophysics Data System (ADS)

    Sahoo, Sarbeswar; Polisetty, Srinivas; Duan, Chun-Gang; Jaswal, Sitaram S.; Tsymbal, Evgeny Y.; Binek, Christian

    2007-09-01

    Reversible control of magnetism is reported for a Fe thin film in proximity of a BaTiO3 single crystal. Large magnetization changes emerge in response to ferroelectric switching and structural transitions of BaTiO3 controlled by applied electric fields and temperature, respectively. Interface strain coupling is the primary mechanism altering the induced magnetic anisotropy. As a result, coercivity changes up to 120% occur between the various structural states of BaTiO3 . Up to 20% coercivity change is achieved via electrical control at room temperature. Our all solid state ferroelectric-ferromagnetic heterostructures open viable possibilities for technological applications.

  11. The ordered double perovskite PrBaCo2O6: Synthesis, structure, and magnetism

    NASA Astrophysics Data System (ADS)

    Motin Seikh, Md.; Pralong, V.; Lebedev, O. I.; Caignaert, V.; Raveau, B.

    2013-07-01

    The stoichiometric layered perovskite cobaltite PrBaCo2O6 has been synthesized using an oxidative reaction of PrBaCo2O5.80 by sodium hypochlorite. The ferromagnetic properties of this oxide, which exhibits the highest TC of 210 K among the "112" layered cobaltites, are interpreted by double exchange mechanism. In contrast, the creation of oxygen vacancies in this framework leads for the oxides PrBaCo2O5+δ (0.80 ≤ δ < 1) to a strong competition between ferromagnetism and antiferromagnetism due to the appearance of superexchange Co3+—O—Co3+ antiferromagnetic interactions.

  12. 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).

  13. Addendum: Safety Standards for Gua sha (press-stroking) and Ba guan (cupping).

    PubMed

    Nielsen, Arya; Kligler, Ben; Koll, Brian S

    2014-06-01

    Our previous article Safety Standards for Gua sha (press-stroking) and Baguan (cupping) discussed the risk of transfer of blood-borne pathogens with Gua sha and Ba guan, identified Gua sha and Ba guan 'instrument criticality' as semi-critical and offered recommendations for safe practice based on hospital disinfection standards. Based on the article's feedback, we feel the need to clarify that Gua sha and Ba guan instruments, if intended for reuse, must undergo high level disinfection (HLD) or, in the case of 'wet-cupping', sterilization. We update our recommendations to be amenable to both private practice and education settings.

  14. Nonstoichiometry and decomposition of La 1+ zBa 2- zCu 3O y and La 4BaCu 5O 13- w

    NASA Astrophysics Data System (ADS)

    Lindemer, T. B.; Specht, E. D.; MacDougall, C. S.; Taylor, G. M.; Pye, S. L.

    1993-10-01

    The temperature ( T, K) and oxygen pressure ( pO 2, Pa) dependence of oxygen content in La 1+ zBa 2- zCu 3O y (123) and La 4BaCu 5O 13- w (415) were determined over the ranges 10 Pa to 0.1 MPa O 2, 0.0≤ z≤0.7 and 523≤ T≤1223 K. The data for each phase were correlated with chemical thermodynamic representations. For La 1+ zBa 2- zCu 3O y, the T- z- y- pO 2 behavior was modeled as a solution of LaBa 2Cu 3O 7- x and 415. The experimental data demonstrated 7- x values <6 at high temperatures, while they exceed 6.99 only at temperatures approaching ambient at 0.1 MPa O 2. These two characteristics are not known to occur in the lanthanide and Y analogues. The T- z- pO 2 dependence of high-temperature decomposition was determined and, in conjunction with X-ray analysis, permitted construction of the phase diagram lying between LaBa 2Cu 3O 7- x and 415. Effects of residual carbonate content were also determined.

  15. 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.

  16. 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.

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

    PubMed

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

    2012-09-01

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

  18. Surface Relaxations, Surface Energies and Electronic Structures of BaSnO3 (001) Surfaces: Ab Initio Calculations

    NASA Astrophysics Data System (ADS)

    Slassi, A.; Hammi, M.; El Rhazouani, O.

    2017-02-01

    The surface relaxations, surface energies and electronic structures of BaO- and SnO2-terminated BaSnO3 (001) surfaces have been studied by employing the first-principles density functional theory. For both terminations, we find that the upper-layer Ba and Sn atoms move inward, whereas upper-layer O atoms move outward from the surface. Moreover, the largest relaxations are occurred on the first-layer atoms of both terminations. The surface rumpling of BaO-terminated BaSnO3 (001) is slightly less than that of the SnO2-terminated BaSnO3 (001) surface. The surface energies show that both terminated surfaces are energetically stable and favorable. Finally, the surface band gap is slightly decreased for the BaO termination, while it is dramatically decreased for the SnO2 termination.

  19. Monoclinic 122-Type BaIr₂Ge₂ with a Channel Framework: A Structural Connection between Clathrate and Layered Compounds.

    PubMed

    Gui, Xin; Chang, Tay-Rong; Kong, Tai; Pan, Max T; Cava, Robert J; Xie, Weiwei

    2017-07-18

    A new 122-type phase, monoclinic BaIr₂Ge₂ is successfully synthesized by arc melting; X-ray diffraction and scanning electron microscopy are used to purify the phase and determine its crystal structure. BaIr₂Ge₂ adopts a clathrate-like channel framework structure of the monoclinic BaRh₂Si₂-type, with space group P2₁/c. Structural comparisons of clathrate, ThCr₂Si₂, CaBe₂Ge₂, and BaRh₂Si2 structure types indicate that BaIr₂Ge₂ can be considered as an intermediate between clathrate and layered compounds. Magnetic measurements show it to be diamagnetic and non-superconducting down to 1.8 K. Different from many layered or clathrate compounds, monoclinic BaIr₂Ge₂ displays a metallic resistivity. Electronic structure calculations performed for BaIr₂Ge₂ support its observed structural stability and physical properties.

  20. Crystal structure of the solid solution Ba8.35Pb0.65(B3O6)6.

    PubMed

    Zhao, Wenwu

    2017-03-01

    Single crystals of lead barium borate, Ba8.35Pb0.65(B3O6)6, octabarium lead(II) hexa-kis-(triborate), have been obtained by spontaneous nucleation from a high-temperature melt. Its three-dimensional structure is constructed on the basis of a BaO9 polyhedron, a (Pb/Ba)O6 octa-hedron (occupancy ratio Pb:Ba = 0.216:0.784) and a condensed B3O6 ring anion. In the crystal, the planar B3O6 anions are stacked in an alternating fashion with Ba and (Pb/Ba) atoms along [001]. A comparison is made with the structures of related solid solutions in the system Ba/Pb/B/O.

  1. Crystal structure of the solid solution Ba8.35Pb0.65(B3O6)6

    PubMed Central

    Zhao, Wenwu

    2017-01-01

    Single crystals of lead barium borate, Ba8.35Pb0.65(B3O6)6, octabarium lead(II) hexa­kis­(triborate), have been obtained by spontaneous nucleation from a high-temperature melt. Its three-dimensional structure is constructed on the basis of a BaO9 polyhedron, a (Pb/Ba)O6 octa­hedron (occupancy ratio Pb:Ba = 0.216:0.784) and a condensed B3O6 ring anion. In the crystal, the planar B3O6 anions are stacked in an alternating fashion with Ba and (Pb/Ba) atoms along [001]. A comparison is made with the structures of related solid solutions in the system Ba/Pb/B/O. PMID:28316806

  2. Physicochemical properties of high-temperature solutions of the systems BaO-B/sub 2/O/sub 3/-Fe/sub 2/O/sub 3/ and BaO-B/sub 2/O/sub 3/-BaF/sub 2/-Fe/sub 2/O/sub 3/ suitable for the growth of BaFe/sub 12/O/sub 19/ single crystals

    SciTech Connect

    Peshev, P.; Varadinov, R.; Nikolov, V. )

    1989-08-01

    The systems BaO-B/sub 2/O/sub 3/-Fe/sub 2/O/sub 3/ and BaO-B/sub 2/O/sub 3/-BaF/sub 2/-Fe/sub 2/O/sub 3/ have been investigated and the concentration and temperature regions of stability of the Ba Fe/sub 12/O/sub 19/ phase in them are determined with a view to choosing suitable solvents and growth conditions of barium hexaferrite single crystals. The temperature dependencies of the dynamic viscosity of solutions of these systems are studied. It is shown that solutions containing BaF/sub 2/ have considerably lower viscosity values. The density and volatility of the solutions at their saturation temperatures are determined. On the basis of the data obtained, an appropriate solvent composition from the system BaO-B/sub 2/O/sub 3/-BaF/sub 2/ is proposed.

  3. 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.

  4. Critical currents and pinning forces in a-axis oriented EuBa2Cu3O7/PrBa2Cu3O7 superlattices

    NASA Astrophysics Data System (ADS)

    Vélez, M.; Martín, J. I.; Vicent, J. L.

    1995-11-01

    a-axis oriented EuBa2Cu3O7/PrBa2Cu3O7 (EBCO/PBCO) superlattices have been grown by dc sputtering. The critical current (JC) behavior is modified by the pinning force arising from the insulating PrBa2Cu3O7 layers, which in a-axis oriented superlattices are perpendicular to the Cu-O planes. Depending on the EBCO and PBCO layer thicknesses the pinning forces deviate from the usual scaling laws as a function of temperature observed in single films. When B is perpendicular to the sample, an exponential dependence of JC(B) appears as the PBCO thickness is increased (coupling is reduced), and also as the thickness of the EBCO layer is reduced.

  5. Is BaCr2As2 symmetrical to BaFe2As2 with respect to half 3 d shell filling?

    NASA Astrophysics Data System (ADS)

    Richard, P.; van Roekeghem, A.; Lv, B. Q.; Qian, Tian; Kim, T. K.; Hoesch, M.; Hu, J.-P.; Sefat, Athena S.; Biermann, Silke; Ding, H.

    2017-05-01

    We have performed an angle-resolved photoemission spectroscopy study of BaCr2As2 , which has the same crystal structure as BaFe2As2 , a parent compound of Fe-based superconductors. We determine the Fermi surface of this material and its band dispersion over 5 eV of binding energy. Very moderate band renormalization (1.35) is observed for only two bands. We attribute this small renormalization to enhanced direct exchange as compared to Fe in BaFe2As2 , and to a larger contribution of the eg orbitals in the composition of the bands forming the Fermi surface, leading to an effective valence count that is reduced by Fe d -As p hybridization.

  6. Effect of reagent vibrational excitation and isotope substitution on the stereo-dynamics of the Ba + HF → BaF + H reaction

    NASA Astrophysics Data System (ADS)

    Zhao, Juan; Luo, Yi

    2011-04-01

    Based on an extended London—Eyring—Polanyi—Sato (LEPS) potential energy surface (PES), the Ba + HF reaction has been studied by the quasi-classical trajectory (QCT) method. The reaction integral cross section as a function of collision energy for the Ba + HF → BaF + H reaction is presented and the influence of isotope substitution on the differential cross sections (DCSs) and alignments of the product's rotational angular momentum have also been studied. The results suggest that the integral cross sections increase with increasing collision energy, and the vibrational excitation of the reagent has great influence on the DCS. In addition, the product's rotational polarization is very strong as a result of heavy-heavy-light (HHL) mass combination, and the distinct effect of isotope substitution on the stereodynamics is also revealed.

  7. Liquidus Diagram of the Ba-Y-Cu-O System in the Vicinity of the Ba2YCu3O6+x Phase Field

    PubMed Central

    Wong-Ng, Winnie; Cook, Lawrence P.

    1998-01-01

    This paper describes the melting equilibria in the vicinity of the high Tc phase Ba2YCu3O6+x, including evidence for two Ba-Y-Cu-O immiscible liquids. Melting equilibria have been investigated in purified air using a combination of differential thermal analysis (DTA), thermogravimetric analysis (TGA), powder x-ray diffraction (XRD), MgO wick entrapment of liquid for analysis, scanning electron microscopy (SEM) coupled with energy dispersive x-ray analysis (EDS), and hydrogen reduction for determination of copper oxidation state. For relatively barium-rich compositions, it was necessary to prepare the starting materials under controlled atmosphere conditions using BaO. A liquidus diagram was derived from quantitative data for the melts involved in various melting reactions. In general the 1/2(Y2O3) contents of the melts participating in these equilibria were low (mole fraction <4 %). The primary phase field of Ba2YCu3O6+x occurs at a mole fraction of <2.0 % 1/2Y2O3 and lies very close along the BaO-CuOx edge, extending from a mole fraction of ≈43 % CuO to a mole fraction of ≈76 % CuO. It is divided by a liquid miscibility gap and extends on either side about this gap. The topological sequence of melting reactions associated with the liquidus is presented as a function of temperature. Implications for the growth of Ba2YCu3O6+x crystals are discussed. PMID:28009382

  8. Fast approximation of average shortest path length of directed BA networks

    NASA Astrophysics Data System (ADS)

    Mao, Guoyong; Zhang, Ning

    2017-01-01

    The average shortest path length is an important feature for complex networks. However, for large networks, it is very difficult to compute it due to the limitation of computing power. By analyzing the node reachability from several real BA networks as the example, we brought forward the concept of Global Reachable Nodes and Local Reachable Nodes. We found that the average shortest path length of a BA network is determined by the Global Reachable Nodes. From the mechanism of the BA network we illustrated this feature and hereby presented a randomized approximation algorithm for computing the average shortest path length. We verified the accuracy of this algorithm using 8 different networks. For large-scale BA network with millions of nodes, the experiments indicate that our method can estimate its ASPL with high accuracy using only several hundreds of Global Reachable Nodes.

  9. [Construction of a recombinant stable Ba/F3 cell strain containing Tpr-Met].

    PubMed

    Shu, Ling-fei; Li, Wei; Zhan, Yi-qun; Xu, Wang-xiang; Yang, Xiao-ming; Li, Chang-yan

    2012-11-01

    To construct a stable cell strain encoding tumor-associated fused gene which expresses oncoprotein Tpr-Met. We transfected Tpr-Met vector into Ba/F3 cells and screened the cell strain stably expressing Tpr-Met. The interleukin 3 (IL-3) independent proliferation of the cells was measured using the MTS assay. The expression of Tpr-Met, the activity of downstream signal transduction pathway and SU11274-induced inhibition of the signal pathway were investigated by Western blotting. We obtained a Ba/F3 cell strain stably expressing Tpr-Met. The cells presented IL-3 independent proliferation, suggesting a malignant transformation of the cell line. In Tpr-Met transformed Ba/F3 cells, the phosphorylation of Met and ERK were enhanced; however, specific c-Met inhibitor SU11274 suppressed the cell proliferation and c-Met phosphorylation. Tpr-Met transformed Ba/F3 strain has been successfully constructed.

  10. Metallic behavior of GaAs/BaTiO3 heterostructure

    NASA Astrophysics Data System (ADS)

    Yuan, Mengqi; Wang, Jianli; Pu, Long; Tang, Gang; Guo, Sandong

    2016-07-01

    The integration of III-V semiconductors on functional perovskite-oxide can lead to new material properties and new device applications by combining the rich properties of perovskite-oxides together with the superior optical and electronic properties of III-V semiconductors. The structural and electronic properties of the surface and interface of the GaAs/BaTiO3 are studied using first-principles calculations. We point out the energetically favorable GaAs/BaTiO3 interfaces according to the GaAs initial adsorption on the BaTiO3(001) substrate. Our calculations predict the existence of the metallic behavior at the GaAs/BaTiO3 interfaces.

  11. 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.

  12. Postannealing effects on undoped BaSi2 evaporated films grown on Si substrates

    NASA Astrophysics Data System (ADS)

    Suhara, Takamichi; Murata, Koichi; Navabi, Aryan; Hara, Kosuke O.; Nakagawa, Yoshihiko; Trinh, Cham Thi; Kurokawa, Yasuyoshi; Suemasu, Takashi; Wang, Kang L.; Usami, Noritaka

    2017-05-01

    Semiconducting BaSi2 is expected as an alternative material for solar cell application because of large absorption coefficients and a suitable bandgap for single-junction solar cells. In this study, the electrical properties of undoped BaSi2 films grown by a simple vacuum evaporation method are explored. The obtained results show that an undoped evaporated film is an n-type semiconductor with a high carrier density of ˜1019 cm-3 and exhibits a metallic behavior. The quality of BaSi2 films is significantly improved by postannealing at 1000 °C with surface covering to prevent oxidation. After annealing, the carrier density of BaSi2 films markedly decreases and the temperature dependence of carrier density changes from being metallic to being semiconducting. By comprehensive structural analysis, it is speculated that postannealing improves the film quality, for example, by decreasing the density of grain boundaries.

  13. 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.

  14. Anomalous properties and nature of Ba 1-xK xBiO 3 superconductivity

    NASA Astrophysics Data System (ADS)

    Golovashkin, A. I.; Anshukova, N. V.; Ivanova, L. I.; Rusakov, A. P.

    1994-12-01

    On the base of temperature dependencies of the specific heat in magnetic fields, thermal expansion and magnetic properties of high quality high-T c Ba 1-xK xBiO 3 ( x = 0,38 - 0,40) it was found that H c2(T) had anomalous upward curvature up to fields 20T and coefficient of thermal expansion was negative at low temperatures. The results contradict the picture of simple electron-phonon coupling. We have presented a model of the electronic ordering in Ba 1-xK xBiO 3 which drives the system to the dielectric-metal phase transition with doping. It was shown that electronic spectrum peculiarities near the Brillouin zone boundary determine the anomalous properties and upward curvature of H c2(T) in BaKBiO. The mechanism of BaKBiO superconductivity is discussed.

  15. 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.

  16. 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

  17. 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.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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.

  20. 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.

  1. 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.

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

    DOE PAGES

    Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; ...

    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

  3. Pyroelectric response of spray-deposited BaTiO3 thin film

    NASA Astrophysics Data System (ADS)

    Peale, Robert E.; Oladeji, Isaiah O.; Smith, Evan M.; Vasilyev, Vladimir; Alhasan, Sarmad Fawzi Hamza; Abouelkhair, Hussain; Todorovski, Dalibor; Kimani, Martin; Cleary, Justin W.

    2016-09-01

    Pyroelectric photoresponse of aqueous spray deposited thin films containing BaTiO3 nano-crystals is reported. X-ray diffraction data indicate the presence of hexagonal BaTiO3 nano-crystals with 20 nm crystalline domains in a matrix of some as yet unidentified nano-crystalline material. When the film is annealed at 600 C, the X-ray pattern changes significantly and indicates a conversion to one of the non-hexagonal phases of BaTiO3 as well as a complete change in the matrix. With suitable amplifier, the measured photoresponse was 40V/W. Ferroelectric hysteresis on a film with significant presence of hexagonal BaTiO3 shows saturated polarization which is about 5-times smaller than for the bulk tetragonal phase. A potential application is a patternable infrared detector for photonic and plasmonic devices, such as chip-scale spectral sensors.

  4. Carbon stars and isotopic BA anomalies in meteoritic SiC grains

    NASA Astrophysics Data System (ADS)

    Gallino, R.; Raiteri, C. M.; Busso, M.

    1993-06-01

    New calculations of s-processing in TP-AGB stars of low mass based on an updated compilation of neutron capture cross sections are presented. It is shown how the reproduction of solar abundances for the s-isotopes of Ba requires a special choice of neutron capture cross sections of Ba-136 and Ba-138. It is further shown how agreement between the predictions of He shell nucleosynthesis and the Ba isotopic mixture of the G-component in SiC can be obtained, once C-stars with mean neutron exposures lower than that required to fit the solar main component are considered. Problems related to the interpretation of other isotope anomalies in SiC are also examined.

  5. Reversible, long-term passivation of Ge(001) by a Ba-induced incorporated phase

    NASA Astrophysics Data System (ADS)

    Koczorowski, W.; Grzela, T.; Puchalska, A.; Jurczyszyn, L.; Czajka, R.; Radny, M. W.

    2017-10-01

    Thermal stability and passivation properties of Ba-induced incorporation phase on Ge(001) under ultra-high vacuum (UHV) conditions are investigated using scanning tunneling microscope (STM). We show that the generic c(4 × 2) reconstruction of Ge(001) can be easily reinstated in the Ba/Ge(001) sample, stored for more than 40 days under UHV and room temperature conditions, just by thermal annealing at 1070 K under UHV. Our data implies that this process occurs predominantly via temperature assisted desorption of Ba adatoms from the on-top phase formed as an intermediate during annealing process and known to preserve the c(4 × 2) reconstruction of Ge(001). The reported results indicate that the Ba-induced incorporated phase on Ge(001) is very effective in protecting the Ge(001) substrate against destructive adsorption of residual gases and can be utilized for long-term, non-destructive Ge sample storage under UHV conditions.

  6. First identification of excited states in Ba117 using the recoil- β -delayed proton tagging technique

    DOE PAGES

    Ding, B.; Liu, Z.; Seweryniak, D.; ...

    2017-02-01

    Excited states have been observed for the first time in the neutron-deficient nucleus 117Ba using the recoil-decay tagging technique following the heavy-ion fusion-evaporation reaction 64Zn(58Ni, 2p3n)117Ba. Prompt γ rays have been assigned to 117Ba through correlations with β-delayed protons following the decay of A = 117 recoils. Through the analysis of the γ–γ coincidence relationships, a high-spin level scheme consisting of two bands has been established in 117Ba. Based on the systematics of the level spacings in the neighboring barium isotopes, the two bands are proposed to have νh11/2[532]5/2– and νd5/2[413]5/2+ configurations, respectively. Lastly, the observed band-crossing properties are interpretedmore » in the framework of cranked shell model.« less

  7. Cyt2Ba of Bacillus thuringiensis israelensis: activation by putative endogenous protease.

    PubMed

    Nisnevitch, Marina; Cohen, Shmuel; Ben-Dov, Eitan; Zaritsky, Arieh; Sofer, Yossef; Cahan, Rivka

    2006-05-26

    The gene cyt2Ba of Bacillus thuringiensis subsp. israelensis was cloned for expression, together with p20, in an acrystalliferous strain. The large hexagonal crystals formed were composed of Cyt2Ba, which facilitated its purification. Crystal solubilization in the presence of endogenous proteases (with spores and cell debris) enabled quick and simple procedure to obtain rather pure and active toxin species by cleavage between amino acid residues 34 and 35, most likely by a camelysin-like protease that was discovered in association with activated Cyt2Ba. The product of this cleavage displayed haemolytic activity comparable to that of exogenously activated Cyt2Ba. The sequence of this putative protease shares high homology with the cell envelope-bound metalloprotease (camelysin) of the closely related species Bacillus cereus.

  8. 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.

  9. Crystal and electronic structures of metallic Ba2Pd5Ge4.

    PubMed

    Saparov, Bayrammurad; Parker, David S; Sefat, Athena S

    2012-11-07

    Crystals of a new intermetallic germanide Ba(2)Pd(5)Ge(4) have been grown out of a binary PdGe flux. Single crystal X-ray diffraction reveals that the compound crystallizes in a novel structure type in the Cmca space group, with a = 10.9296(9) Å, b = 14.1639(12) Å, and c = 5.8808(5) Å at 173(2) K. This structure type features a three-dimensional [Pd(5)Ge(4)] network made of distorted tetrahedral and square planar PdGe(4) units, with Ba atoms filling the voids. The magnetic susceptibility and the electrical resistivity measurements show that Ba(2)Pd(5)Ge(4) is a Pauli paramagnet and a metal with the room temperature resistivity value of ρ(300 K) ≈ 0.096 mΩ cm. The band structure calculations confirm that Ba(2)Pd(5)Ge(4) is a good metal with no magnetic instability.

  10. Formation of new structural states in compressed BaTiO3 nanopowders

    NASA Astrophysics Data System (ADS)

    Shmyt'ko, I. M.; Frolov, D. D.; Aronin, A. S.; Ganeeva, G. R.; Kedrov, V. V.

    2017-06-01

    The structural changes in BaTiO3 nanocrystal powder and tablets have been probed via X-ray diffraction, scanning electron and transmission microscopy, and differential calorimetry after successive hightemperature annealing in air. It is shown that, beginning with the annealing temperature of 1200°C, significant amount of the Ba2TiO4 phase forms in the tablets together with the BaTiO3 phase. This phase is equilibrium one; it practically vanishes when the annealing temperature decreases to 700-600°C; and this phase practically restored to the initial state when the annealing temperature is again increased to 1200°C. Annealing the powders causes no formation of new phases, but an increase in their crystallite sizes. A probable reason of the emergence of Ba2TiO4 phase in tablets and its absence in free powder is discussed, as well.

  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. 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.

  13. 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).

  14. Surface electronic structures of Ba overlayers on W(100), W(110), and W(111)

    NASA Astrophysics Data System (ADS)

    Ibrahim, Z. A.; Lee, M. J. G.

    2007-10-01

    The total energy distributions (TEDs) in field emission (FE) and photofield emission (PFE) and the work functions have been measured at room temperature for Ba adsorbed on W(100), W(110), and W(111) in the range of coverage from 0 to 1 ML (monolayer). We observe two initial state peaks and three final state peaks on W(100)/Ba , six initial state peaks and one final state peak on W(110)/Ba , and two initial state peaks and two final state peaks on W(111)/Ba . We extend the full-potential linear augmented plane wave method for the electronic structures of periodic lattices to calculate the emission current in FE and surface PFE at a metal-adsorbate-vacuum interface. Our calculations account for the energies of all of the initial state features observed experimentally in FE and surface PFE from clean W(100), in PFE and angle-resolved inverse photoemission spectroscopy from W(100)/Ba at 1 ML, and for all of the peaks observed in FE, surface PFE, and photoemission from W(110)/Ba at 0.6 ML and from W(111)/Ba at 1 ML. The dz2 -like surface states of the Swanson hump [L. W. Swanson and L. C. Crouser, Phys. Rev. Lett. 16, 389 (1966)] of clean W(100) hybridize with s -like states of the c(2×2) overlayer and are shifted by -1.60eV to yield a prominent peak in PFE. An isolated Ba c(2×2) layer is found to be weakly metallic; the metallicity is greatly enhanced when it is adsorbed on a W(100) substrate. The TEDs in PFE from the atomically less dense overlayer W(110)/Ba (2×2) are dominated by substrate-overlayer interactions, while those from the atomically denser overlayer W(111)/Ba (1×1) are dominated by interactions within the overlayer. Our results yield evidence that above 1/3 ML Ba coverage on W(111), which corresponds to a commensurate (31/2×31/2)R30° overlayer, the interstitial sites fill in randomly to form a commensurate (1×1) overlayer at 1 ML coverage.

  15. 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

  16. 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}.

  17. BaO Planes, not CuO2 Planes, Contain HIGH-TC Superconductivity

    NASA Astrophysics Data System (ADS)

    Dow, John D.; Harshman, Dale R.

    Muon spin rotation (μ+SR) measurements conducted on crystalline YBa2Cu3O7 are consistent with s-wave pairing, not d-wave, suggesting that the superconducting hole condensate resides in the BaO layers, not in the cuprate-planes. The specific heat and thermal conductivity data are explained by the superconducting BaO layers alone, unlike the failed interpretation based on CuO2-plane superconductivity. The layer charges of the CuO2 planes are almost -2 |e|, indicating that those planes are primarily carriers of electrons, not holes. The cuprate-planes are not the dominant hole-carriers of high-TC superconductivity, as demonstrated by doped YBa2RuO6, which has no such CuO2 lanes, yet superconducts at ~ 93 K. Moreover the trio of related compounds, YSr2RuO6 (doped with Cu on Ru sites), undoped GdSr2Cu2RuO8, and undoped Gd2-zCezSr2Cu2RuO10 all start superconducting near 49 K in their SrO layers, not in the cuprate planes of the two compounds that have such planes, because those planes are either antiferromagnetic or weakly ferromagnetic and so do not superconduct. In PrBa2Cu3O7, a Pr-on-Ba-site (PrBa) defect kills the superconductivity, but Pr-on-Pr-site (PrPr) does not. Both defects are approximately equidistant from the intervening cuprate plane, suggesting that the cuprate plane does not carry significant superconductivity. In GdBa2Cu3O7, Gd-on-a-Gd-site (GdGd) does not break Cooper pairs, but Gd-on-a-Ba-site (GdBa) does, indicating that the superconductivity is in the BaO layers, and not in the cuprate-planes. In HgBa2Can-1CunO2n+2, the BaO layers, not the cuprate-planes, gain positive charge as TC, pressure, and the number of layers n increase. The reason that theories based on holes in the cuprate-planes have done so poorly is that those planes were incorrectly identified as the source of high-temperature superconductivity on the basis of a single datum by Cava et al., that was first contradicted by Jorgensen et al., and then endorsed by Jorgensen alone on the

  18. Bulk superconductivity in Tl 2Ba 2CaCu 2O 8 and TlBa 2Ca 2Cu 3O 9 phases

    NASA Astrophysics Data System (ADS)

    Sulpice, A.; Giordanengo, B.; Tournier, R.; Hervieu, M.; Maignan, A.; Martin, C.; Michel, C.; Provost, J.

    1988-09-01

    Well-crystallized Tl 2Ba 2CaCu 2O 8 phases have been observed superconducting or normal below 108 K depending on their stoichiometry. This observation is an evidence that a (Cu IL&.zbnd;O -) mixed valence induced by vacancies or substitution on different sites gives rise to superconductivity in this phase. The new phase TlBa 2Ca 2CuO 9 which intrinsically contains a mixed valence has been observed as having a sharp transition to bulk superconductivity in the Meissner effect at a critical temperature of 120 K. This temperature is much higher than the recently observed one.

  19. 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.

  20. 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.

  1. 137 Ba Double Gamma Decay Measurement with GAMMASPHERE

    DOE PAGES

    Merchán, E.; Moran, K.; Lister, C. J.; ...

    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

  2. Radiation damage in BaF[sub 2] crystals

    SciTech Connect

    Woody, C.L.; Kierstead, J.A.; Levy, P.W.; Stoll, S.

    1991-01-01

    The effects of radiation damage and recovery have been studied in BaF[sub 2] crystals exposed to [sup 60]Co radiation. The change in optical transmission and scintillation light output have been measured as a function of dose up to 4.7 [times] 10[sup 6] rad. Although some crystals exhibit a small change in transmission, a greater change in scintillation light output is observed. Several 25 cm long crystals whichhave been irradiated show large changes in both transmission and light output. Recovery from radiation damage has been studied as a function of time and exposure to UV light. A long lived radiation induced phosphorescence has been observed in all irradiated samples which is distinct from the standard fast and slow scintillation emissions. The emission spectrum of the phosphorescence has been measured and shown a peakat [approximately]330 nm, near the region of the slow scintillation component. Results are given on the dependence of the decay time of the phosphorescence with dose.

  3. Radiation damage in BaF{sub 2} crystals

    SciTech Connect

    Woody, C.L.; Kierstead, J.A.; Levy, P.W.; Stoll, S.

    1991-12-31

    The effects of radiation damage and recovery have been studied in BaF{sub 2} crystals exposed to {sup 60}Co radiation. The change in optical transmission and scintillation light output have been measured as a function of dose up to 4.7 {times} 10{sup 6} rad. Although some crystals exhibit a small change in transmission, a greater change in scintillation light output is observed. Several 25 cm long crystals whichhave been irradiated show large changes in both transmission and light output. Recovery from radiation damage has been studied as a function of time and exposure to UV light. A long lived radiation induced phosphorescence has been observed in all irradiated samples which is distinct from the standard fast and slow scintillation emissions. The emission spectrum of the phosphorescence has been measured and shown a peakat {approximately}330 nm, near the region of the slow scintillation component. Results are given on the dependence of the decay time of the phosphorescence with dose.

  4. 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.

  5. Theoretical study of Ge/ BaTiO 3 Interfaces

    NASA Astrophysics Data System (ADS)

    Fredrickson, Kurt; Demkov, Alexander

    2011-03-01

    It has been shown (McKee et al., Phys. Rev. Lett. 81, 3014 (1998), and R. McKee, et al., Science 293 , 468 (2001)) that perovskite oxides SrTi O3 and BaTi O3 (BTO) can be grown epitaxially on Si and Ge, respectively. It would be interesting to achieve the reverse, i.e. to grow for example, Ge on BTO. It is not clear, however, whether one can achieve wetting of BTO by Ge. Theoretically, the energy of the Ge (001) surface is estimated to be anywhere between 591 and 1700 erg/cm2 and the surface energy of BTO is in the range of 1083-1496 erg/cm2 depending on termination and environment. The missing piece of information is the energy of the Ge/BTO interface. We examine five possible Ge/BTO interface structures and calculate their energies using density functional theory to determine which one has the lowest energy, and whether wetting can be achieved.

  6. New oxybromide cobaltites with layered perovskite-related structures: 18R-Ba(6)Co(5)BrO(14) and 14H-Ba(7)Co(6)BrO(17).

    PubMed

    Kauffmann, Matthieu; Roussel, Pascal

    2007-08-01

    Single crystals of the title compounds were prepared by solid-solid reaction using BaBr(2) flux at 1373 K. The structures of these two new cobaltites were solved and refined. The two compounds are built from a close-packing of [BaO(3)] and [BaOBr] layers with stacking sequences (c'chhcc')(3) and (c'chhhcc')(2) for the 18R and 14H structures, respectively, which create Co(3)O(12) trimers or Co(4)O(15) tetramers of face-sharing octahedra connected at their extremities to isolated tetrahedra by corner-sharing. These new materials are strongly related to the 5H-Ba(5)Co(5)O(14)/12H-Ba(0.9)CoO(2.6) and 10H-Ba(5)Co(5)ClO(13)/6H-Ba(6)Co(6)ClO(16) materials, with the existence of common blocks. In Ba(6)Co(5)BrO(14) and Ba(7)Co(6)BrO(17), all the atoms in the vicinity of the [BaOBr] layers are disordered, whereas the rest of the structure is perfectly ordered.

  7. Chemistry and High Tc Superconductivity in the La-Ba-Cu-O System

    DTIC Science & Technology

    1988-07-15

    11.62(0) 78.4 340 1.0 3.868(1) 11.62(1) 80.5 The lattice parameters decrease uniformly with increasing x in LaBa2., CaCu 3 0 7 6 , relative to "pure" La...to 80 K as the calcium content increases. Fig. 9 illustrates the temperature dependence of the resistivity of the LaBa 2 _, CaCu 30 7 6 samples. In La

  8. 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.

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

    SciTech Connect

    Minseo, Park

    1994-05-10

    The relation of structure to lack of superconductivity in Pr-Ba-Cu-O was systematically investigated. First, the phase equilibria of this system was studied to find the processing parameters which maximize the cation-site ordering between Pr and Ba ions. Second, a comparative study between superconducting Nd-Ba-Cu-0 and non- superconducting Pr-Ba-Cu-0 was performed by forming solid-solution Nd- Pr-Ba-Cu-0. The relation between structure and superconductivity in Ndb1-xPrxBa2Cu3O7-δ is investigated. Tc decreases monotonically with increasing x and superconductivity disappears at around x=0.3-0.4. Tc is enhanced by 10K when the sample is processed at an oxygen partial pressure (PO2) of 0.01 atm, followed by oxygenation at 450C. Depression of (Tc) as a function of x and PO 2 is explained in terms of a charge-transfer model. It is suggested that destruction of superconductivity in the RE1-xPrxBa2CU3O7-δ (RE=rare-earth) system can be viewed as disruption of four-fold planar coordinated Cu ions in the chain-site due to permanent occupation of extra Pr ions on Ba sites.

  10. Tumor cure studies on the rat sarcoma BA1112 using continuous low-dose-rate radiation

    SciTech Connect

    Peschel, R.E.; Martin, D.F.; Fischer, J.J.

    1984-09-01

    Delivery of continous low-dose-rate radiation at a constant rate using an afterloading plastic helmet system can achieve the local cure of the BA1112 rat sarcoma. Complete dose response curves for local tumor cure have been obtained at 170 rad (1.7 Gy) and 130 rad (1.3 Gy) per hour. The results are consistent with the known radiobiological properties of the BA1112 tumor.

  11. Local environment analysis of Fe ions in BaMgSiO4

    NASA Astrophysics Data System (ADS)

    Kase, Junya; Shingaki, Yoshihiro; Inaba, Yuta; Meguro, Kazune; Murata, Hidenobu; Okajima, Toshihiro; Yamamoto, Tomoyuki

    2016-08-01

    Polycrystalline Fe-doped BaMgSiO4 is synthesized by the conventional solid state reaction method, which shows strong photochromism. Photochromic property of the synthesized specimens is investigated by measuring the diffuse reflectance spectrum. Local environment of doped Fe ions in BaMgSiO4 has been studied by the analysis of the X-ray absorption near-edge structure (XANES) spectrum with the aid of the first-principles calculations.

  12. Structure and magnetic properties of Zn-Ti-substituted Ba-ferrite particles for magnetic recording

    NASA Astrophysics Data System (ADS)

    Wang, C. S.; Wei, F. L.; Lu, M.; Han, D. H.; Yang, Z.

    1998-03-01

    The formation process of Zn-Ti-doped Ba-ferrite particles was investigated by the X-ray diffraction technique, transmission electron microscope and magnetic measurements. The effects of heating temperature Th and the Zn-Ti substitution x on the microstructure and magnetic properties of BaFe 12-2 xZn xTi x O 19 particles with x=0.10-0.80 were studied. The temperature dependence of magnetic properties of these particles was measured.

  13. Hidradenitis suppurativa (HS): An unrecognized paradoxical effect of biologic agents (BA) used in chronic inflammatory diseases.

    PubMed

    Faivre, Coline; Villani, Axel Patrice; Aubin, François; Lipsker, Dan; Bottaro, Martine; Cohen, Jean-David; Durupt, François; Jeudy, Géraldine; Sbidian, Emilie; Toussirot, Eric; Badot, Valérie; Barbarot, Sébastien; Debarbieux, Sébastien; Delaporte, Emmanuel; Goegebeur, Guetty; Morel, Jacques; Nassif, Aude; Duru, Gérard; Jullien, Denis

    2016-06-01

    Paradoxical hidradenitis suppurativa (HS) induced by biologic agents (BA) is scarcely reported. We sought to describe the clinical characteristics and outcome of patients developing paradoxical HS under BA. This was a multicenter nationwide retrospective study asking physicians to report all cases of HS, confirmed by a dermatologist, occurring during treatment of an inflammatory disease by a BA. We included 25 patients (15 inflammatory rheumatism, 9 Crohn's disease, 1 psoriasis) treated by 5 BA (adalimumab = 12, infliximab = 6, etanercept = 4, rituximab = 2, tocilizumab = 1). Median duration of BA exposure before HS onset was 12 (range 1-120) months. Patients were mostly Hurley stage I (n = 13) or II (n = 11). Simultaneously to HS or within 1 year, 11 patients developed additional inflammatory diseases, including paradoxical reactions (psoriasis = 9, Crohn's disease = 3, alopecia areata = 1, erythema elevatum diutinum = 1). Complete improvement of HS was more frequently obtained after BA discontinuation or switch (n = 6/10, 60%) rather than maintenance (n = 1/14, 7%). Reintroducing the same BA resulted in HS relapse in 3 of 3 patients. Retrospective nature and lack of complete follow-up for some patients are limitations. HS is a rare paradoxical adverse effect of BA, but fortuitous association cannot be excluded in some cases. We observed a trend toward better outcome when the BA was discontinued or switched. Copyright © 2016 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

  14. The protective effect of betulinic acid (BA) diabetic nephropathy on streptozotocin (STZ)-induced diabetic rats.

    PubMed

    Xie, Rui; Zhang, Hong; Wang, Xing-Zhou; Yang, Xiao-Zhong; Wu, Shang-Nong; Wang, Hong-Gang; Shen, Peng; Ma, Tian-Heng

    2017-01-25

    The present study was designed to investigate the protective effect of betulinic acid (BA) on streptozotocin (STZ)-induced diabetic rats. The rats were intraperitoneally injected with STZ (35 mg kg(-1)). 7 days later, the animals were intragastrically administered with metformin (MET, 150 mg kg(-1)), BA (20 mg kg(-1)) or BA (40 mg kg(-1)) once daily for consecutive 30 days. The blood glucose, the contents of insulin, interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in serum were examined. The levels of IL-6, IL-1β, TNF-α, superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) in kidney tissues were measured. Moreover, the histopathological alteration and the protein expressions of the signaling pathway were detected by hematoxylin and eosin (H&E) staining and western blotting, respectively. BA significantly decreased the levels of serum insulin, IL-6, IL-1β, TNF-α and blood glucose. In addition, BA increased the activities of SOD, CAT and reduced the contents of MDA, IL-6, IL-1β, and TNF-α in kidney tissues. BA also ameliorated the histopathological condition. Furthermore, BA attenuated the phosphorylations of p-adenosine 5'-monophosphate-activated protein kinase (AMPK), nuclear factor kappaB (NF-κB), and an inhibitor of NF-κB (IκBα) and the expressions of NF-E2-related factor 2 (Nrf2) and heme oxygenase (HO)-1. These findings demonstrated that BA exhibited a protective effect on diabetic nephropathy in STZ-induced rats possibly through the AMPK/NF-κB/Nrf2 pathway.

  15. 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.

  16. 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).

  17. 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).

  18. 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.

  19. Exploring the potential of semiconducting BaSi2 for thin-film solar cell applications

    NASA Astrophysics Data System (ADS)

    Suemasu, Takashi; Usami, Noritaka

    2017-01-01

    Semiconducting barium disilicide (BaSi2), which is composed of earth-abundant elements, has attractive features for thin-film solar cell applications. Both a large absorption coefficient comparable to copper indium gallium diselenide and a minority-carrier diffusion length much larger than the grain size of BaSi2 can be used to improve solar cell properties. In this review article, we explore the potential of semiconducting BaSi2 film for thin-film solar cell applications. We start by describing its crystal and energy band structure, followed by discussing thin-film growth techniques and the optical and electrical properties of BaSi2 films. We use a first-principles calculation based on density-functional theory to calculate the position of the Fermi level to predict the carrier type of impurity-doped BaSi2 films using either a group 13 or 15 element, and compare the calculated results with the experimental ones. Special attention was paid to the minority-carrier properties, such as minority-carrier lifetime, minority-carrier diffusion length, and surface passivation. The potential variations across the grain boundaries measured by Kelvin-probe force microscopy allowed us to detect a larger minority-carrier diffusion length in BaSi2 on Si(1 1 1) compared with BaSi2 on Si(0 0 1). Finally, we demonstrate the operation of p-BaSi2/n-Si heterojunction solar cells and discuss prospects for future development.

  20. Nuclear electric dipole moments for the lowest 1/2+ states in Xe and Ba isotopes

    NASA Astrophysics Data System (ADS)

    Yoshinaga, N.; Higashiyama, K.; Arai, R.; Teruya, E.

    2014-04-01

    The electric dipole moments for the lowest 1/2+ states of Xe and Ba isotopes are calculated in terms of the nuclear shell model, which includes two-body nucleon interactions violating parity and time-reversal invariance. Using the wave functions thus obtained, the nuclear electric dipole moments arising from the intrinsic nucleon electric dipole moments and also from asymmetric charge distribution are calculated. The upper limits for the nuclear electric dipole moments of Xe and Ba isotopes are estimated.

  1. Mesoporous BaSnO3 layer based perovskite solar cells.

    PubMed

    Zhu, Liangzheng; Shao, Zhipeng; Ye, Jiajiu; Zhang, Xuhui; Pan, Xu; Dai, Songyuan

    2016-01-18

    One of the limitations of TiO2 based perovskite solar cells is the poor electron mobility of TiO2. Here, perovskite oxide BaSnO3 is used as a replacement. It has a higher electron mobility and the same perovskite structure as the light harvesting materials. After optimization, devices based on BaSnO3 showed the best performance of 12.3% vs. 11.1% for TiO2.

  2. 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.

  3. 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.

  4. Ferroelectric and ferromagnetic properties in BaTiO3 thin films on Si (100)

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    In this paper, we report on the epitaxial integration of room temperature lead-free ferroelectric BaTiO3 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 BaTiO3/SrRuO3/MgO/TiN/Si (100) heterostructures. C-axis oriented and cube-on-cube epitaxial BaTiO3 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 BaTiO3. Furthermore, laser irradiation of BaTiO3 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 BaTiO3 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.

  5. Photoluminescent BaMoO 4 nanopowders prepared by complex polymerization method (CPM)

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

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

  6. 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.

  7. 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.

  8. Electrical and magnetic properties of hexagonal BaTiO3-δ

    NASA Astrophysics Data System (ADS)

    Kolodiazhnyi, T.; Belik, A. A.; Wimbush, S. C.; Haneda, H.

    2008-02-01

    The electrical resistivity, Hall coefficient, and magnetic susceptibility of n -type hexagonal BaTiO3-δ (hex-BaTiO3-δ) have been measured in the 5-400K temperature range. Above 200K this compound undergoes a transition from an insulating to a semiconducting state. Below 140K Hall effect data indicate the existence of an energy gap of approximately 43meV separating the localized electron ground state from the conduction band. Magnetic measurements reveal a strong magnetic anomaly in hex-BaTiO3-δ with a maximum in the susceptibility at around 160-200K . This anomaly is quite similar to that of the hexagonal BaMg1/3Ru2/3O3 which may indicate that the electron ground state in hex-BaTiO3-δ is comprised of spin singlet Ti3+-Ti3+ dimers. We further propose that the thermal dissociation of these dimers is responsible for the change in the electron transport mechanism in hex-BaTiO3-δ .

  9. Ba-ion extraction and identification from high pressure Xenon gas for nEXO

    NASA Astrophysics Data System (ADS)

    Lan, Yang; Brunner, Thomas; Fudenberg, Daniel; Varentsov, Victor; Dilling, Jens; Gratta, Giorgio; nEXO Collaboration

    2016-09-01

    The Enriched Xenon Observatory (EXO) is searching for the lepton-number violating double beta decay (0 νββ) in 136Xe. If experimentally confirmed, 0 νββ will require the neutrino to be a MAJORANA particle, and shed light on the neutrino-mass hierarchy. The currently running EXO-200 experiment has obtained the limit of T1/ 2 0 νββ >= 1 . 1 ×1025 years. In parallel, the development of nEXO has started and is expected to probe the inverted mass hierarchy of neutrino. One of the design goals of nEXO is to unambiguously differentiate true double beta decay events from background contributions through Ba-tagging, i.e. by identifying the daughter isotope 136Ba. With an efficient Ba-Tagging technique, the backgournds can be virtually eliminated. A setup is being developed for Ba-tagging in xenon gas. Its central component is an RF-funnel to extract Ba-ions from high pressure xenon gas (up to 10 bar). The second stage, a linear Paul trap, cools the ions through buffer gas and bunches them into a multi-reflection time-of-flight mass spectrometer for ion identification. The RF-funnel has been built and tested. The liner Paul trap is currently under development. The Ba-tagging setup will be presented and future works will be discussed.

  10. Synthesis, crystal structure, bonding, and properties of (Ba6O)(OsN3)2.

    PubMed

    Schmidt, Carsten L; Wedig, Ulrich; Dinnebier, Robert; Jansen, Martin

    2008-11-13

    The new barium nitridoosmate oxide (Ba(6)O)(OsN(3))(2) was prepared by reacting elemental barium and osmium (3:1) in nitrogen at 815-830 degrees C. The crystal structure of (Ba(6)O)(OsN(3))(2) as determined by laboratory powder X-ray diffraction (R3, No 148: a = b = 8.112(1) A, c = 17.390(1) A, V = 991.0(1) A(3), Z = 3), consists of sheets of trigonal OsN(3) units and trigonal-antiprismatic Ba(6)O groups, and is structurally related to the "313 nitrides" AE(3)MN(3) (AE = Ca, Sr, Ba, M = V-Co, Ga). Density functional calculations, using a hybrid functional, likewise indicate the existence of oxygen in the Ba(6) polyhedra. The oxidation state 4+ of osmium is confirmed, both by the calculations and by XPS measurements. The bonding properties of the OsN(3)(5-) units are analyzed and compared to the Raman spectrum. The compound is paramagnetic from room temperature down to T = 10 K. Between room temperature and 100 K it obeys the Curie-Weiss law (mu = 1.68 mu(B)). (Ba(6)O)(OsN(3))(2) is semiconducting with a good electronic conductivity at room temperature (8.74x10(-2) ohms(-1) cm(-1)). Below 142 K the temperature dependence of the conductivity resembles that of a variable-range hopping mechanism.

  11. High-pressure synthesis and superconductivity of a new binary barium germanide BaGe3.

    PubMed

    Fukuoka, Hiroshi; Tomomitsu, Yusuke; Inumaru, Kei

    2011-07-04

    A new binary barium germanide BaGe(3) was prepared by high-pressure and high-temperature reactions using a Kawai type multi-anvil press. It crystallizes in a hexagonal unit cell with a = 6.814(1) Å, c = 5.027(8) Å, and V = 202.2(5) Å(3) (the space group P6(3)/mmc, No. 194). The unit cell contains two layers along the c axis composed of Ba atoms and Ge(3) triangular units. The triangular units stack along the c axis to form 1D columns in which the adjacent Ge(3) units turn to opposite directions. The columns, therefore, can be described as the face-sharing stacking of elongated Ge(6) octahedra. Each Ba atom is surrounded by six columns. BaGe(3) is metallic and shows superconductivity at 4.0 K. The band structure calculations revealed that there are four conduction bands mainly composed of Ge 4p and Ba 5d orbitals. From Fermi surface analysis, we confirmed that three of them have a large contribution of Ge 4pz orbitals in the vicinity of the Fermi level and show a simple 1D appearance. The remaining one contains Ge 4px, 4py, and Ba 5d contributions and shows a 2D property.

  12. Brief Behavioural Activation (Brief BA) for Adolescent Depression: A Pilot Study.

    PubMed

    Pass, Laura; Lejuez, Carl W; Reynolds, Shirley

    2017-07-31

    Depression in adolescence is a common and serious mental health problem. In the UK, access to evidence-based psychological treatments is limited, and training and employing therapists to deliver these is expensive. Brief behavioural activation for the treatment of depression (BATD) has great potential for use with adolescents and to be delivered by a range of healthcare professionals, but there is limited empirical investigation with this group. To adapt BATD for depressed adolescents (Brief BA) and conduct a pilot study to assess feasibility, acceptability and clinical effectiveness. Twenty depressed adolescents referred to the local NHS Child and Adolescent Mental Health service (CAMHs) were offered eight sessions of Brief BA followed by a review around one month later. Self- and parent-reported routine outcome measures (ROMs) were collected at every session. Nineteen of the 20 young people fully engaged with the treatment and all reported finding some aspect of Brief BA helpful. Thirteen (65%) required no further psychological intervention following Brief BA, and both young people and parents reported high levels of acceptability and satisfaction with the approach. The pre-post effect size of Brief BA treatment was large. Brief BA is a promising innovation in the treatment of adolescent depression. This approach requires further evaluation to establish effectiveness and cost effectiveness compared with existing evidence-based treatments for adolescent depression. Other questions concern the effectiveness of delivery in other settings and when delivered by a range of professionals.

  13. The (3×2) phase of Ba adsorption on Si(001)-2×1

    NASA Astrophysics Data System (ADS)

    Hu, X.; Yao, X.; Peterson, C. A.; Sarid, D.; Yu, Z.; Wang, J.; Marshall, D. S.; Droopad, R.; Hallmark, J. A.; Ooms, W. J.

    2000-01-01

    The initial stages and surface structures of the (3×2) phase of Ba adsorption on an Si(100)-2×1 surface held at 900°C have been studied by low-energy electron diffraction, Auger electron spectroscopy, and ultra-high vacuum scanning tunneling microscopy (STM). At low coverages (<{1}/{6} ML), the Ba atoms form atomic chains across the Si dimer rows by occupying valley bridge sites, as well as on fourfold sites by replacing Si dimers and exhibiting a local (3×2) phase, with the 3×-phase along the Si dimer row direction. Two different configurations for the (3×2) phase, namely, mono- and dimer-Ba models, are proposed based on the STM images. Below a coverage of {1}/{6} ML, the (3×2) phase is formed by single Ba atoms at fourfold sites by replacing original Si dimers. For a Ba coverage of {1}/{3} ML, the (3×2) phase is formed by buckled Ba dimers, as revealed by high-resolution STM images.

  14. Recent increase in Ba concentrations as recorded in a South Pole ice core

    NASA Astrophysics Data System (ADS)

    Korotkikh, Elena V.; Mayewski, Paul A.; Dixon, Daniel; Kurbatov, Andrei V.; Handley, Michael J.

    2014-06-01

    Here we present high-resolution (∼9.4 samples/year) records of Ba concentrations for the period from 1541 to 1999 A.D. obtained from an ice core recovered at the South Pole (US ITASE-02-6) site. We note a significant increase in Ba concentration (by a factor of ∼23) since 1980 A.D. The Ba crustal enrichment factor (EFc) values rise from ∼3 before 1980 A.D. to ∼32 after 1980 A.D. None of the other measured major and trace elements reveal such significant increases in concentrations and EFc values. Comparison with previously reported Antarctic Ba records suggests that significant increases in Ba concentrations at South Pole since 1980 A.D. are most likely caused by local source pollution. The core was collected in close proximity to Amundsen-Scott South Pole Station; therefore activities at the station, such as diesel fuel burning and intense aircraft activity, most likely caused the observed increase in Ba concentrations and its EFc values in the South Pole ice core record.

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

    NASA Astrophysics Data System (ADS)

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

    2017-09-01

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

  16. Pressure-induced Phase Transition in BaCrO4

    SciTech Connect

    Huang, T.; Shieh, S; Akhmetov, A; Liu, X; Lin, C; Lee, J

    2010-01-01

    BaCrO{sub 4} was studied to 25 GPa in a diamond-anvil cell using both Raman spectroscopy and x-ray diffraction methods. Our results showed that BaCrO{sub 4} exhibits a phase transition near 9 GPa from both Raman and x-ray diffraction measurements. The new high-pressure phase (BaCrO{sub 4}-II) is suggested as a monoclinic (P2{sub 1}/m) structure, different from other high-pressure forms of ABO{sub 4}-type compounds. Moreover, the high-pressure phase of BaCrO{sub 4} is found to be reversible; the low-pressure phase is recovered at -8 GPa upon decompression. The pressure-volume data of BaCrO{sub 4} fitted to a third-order Birch-Murnaghan equation of state yield a bulk modulus of 53(1) GPa and a pressure derivative of 6.8(5), in agreement with the theoretical prediction. For the high-pressure phase BaCrO{sub 4}-II, the bulk modulus is 117(10) GPa and the pressure derivative is 3(1).

  17. Gd-doped BaSnO3: A transparent conducting oxide with localized magnetic moments

    NASA Astrophysics Data System (ADS)

    Alaan, Urusa S.; Shafer, Padraic; N'Diaye, Alpha T.; Arenholz, Elke; Suzuki, Y.

    2016-01-01

    We have synthesized transparent, conducting, paramagnetic stannate thin films via rare-earth doping of BaSnO3. Gd3+ (4f7) substitution on the Ba2+ site results in optical transparency in the visible regime, low resistivities, and high electron mobilities, along with a significant magnetic moment. Pulsed laser deposition was used to stabilize epitaxial Ba0.96Gd0.04SnO3 thin films on (001) SrTiO3 substrates, and compared with Ba0.96La0.04SnO3 and undoped BaSnO3 thin films. Gd as well as La doping schemes result in electron mobilities at room temperature that exceed those of conventional complex oxides, with values as high as 60 cm2/V.s (n = 2.5 × 1020 cm-3) and 30 cm2/V.s (n = 1 × 1020 cm-3) for La and Gd doping, respectively. The resistivity shows little temperature dependence across a broad temperature range, indicating that in both types of films the transport is not dominated by phonon scattering. Gd-doped BaSnO3 films have a strong magnetic moment of ˜7 μB/Gd ion. Such an optically transparent conductor with localized magnetic moments may unlock opportunities for multifunctional devices in the design of next-generation displays and photovoltaics.

  18. Characterization of BaCl 2 scintillation crystal at low temperature

    NASA Astrophysics Data System (ADS)

    Kim, M. J.; Kim, H. J.; Park, H.; Kim, Sunghwan; Kim, Jung-in

    2011-03-01

    A BaCl 2 scintillation crystal was grown by the Czochralski method. The grown crystal was cut to a size of 10×10×5 mm 3. The scintillation properties of the crystal such as pulse height spectra, energy resolution, and fluorescence decay time were measured with a 137Cs (662 keV) γ-ray source at room temperature. We measured the temperature dependence of the scintillation light yield and decay time with a bi-alkali photomultiplier tube for the BaCl 2 crystal. The BaCl 2 crystal was cooled down with compressed helium gas from room temperature to 10 K. We measured the light yield and decay time changes of the BaCl 2 crystal from 10 K to room temperature. The light yield of the BaCl 2 at 200 K was four times higher than that at room temperature. The decay time increases as temperature decreases. The BaCl 2 scintillation crystal has a low light yield but a fast decay time so that it can be a calorimeter candidate for high energy physics experiments.

  19. Giant dipole resonance studies in Ba isotopes at E /A ≈5 MeV

    NASA Astrophysics Data System (ADS)

    Ghosh, C.; Kumar, A. K. Rhine; Dey, Balaram; Nanal, V.; Pillay, R. G.; Arumugam, P.; Anoop, K. V.; Dokania, N.; Garai, Abhijit; Gupta, Ghnashyam; Mirgule, E. T.; Mishra, G.; Mondal, Debasish; Pal, S.; Pose, M. S.; Rout, P. C.

    2017-07-01

    Exclusive measurements of high-energy γ rays have been performed in 124Ba and 136Ba at the same excitation energy (˜49 MeV ) to study the properties of the giant dipole resonance (GDR) over a wide N /Z range. The high-energy γ rays are measured in coincidence with the multiplicity of low-energy γ rays to disentangle the effect of temperature (T ) and angular momentum (J ). The GDR parameters are extracted employing a simulated Monte Carlo statistical model analysis. The observed γ -ray spectra of 124Ba can be explained with prolate deformation, whereas a single-component Lorentzian function which corresponds to a spherical shape could explain the γ -ray spectra of 136Ba. The observed GDR width in 136Ba is narrower compared to that of 124Ba. The statistical model best-fit GDR cross sections are found to be in reasonable agreement with the thermal shape fluctuation model (TSFM) calculations. Further, it is shown that the variation of GDR width with T is well reproduced by the TSFM calculations over the temperature range of 1.1-1.7 MeV.

  20. 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.

  1. 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

    2013-10-07

    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.

  2. Atomistic description for temperature-driven phase transitions in BaTiO3

    NASA Astrophysics Data System (ADS)

    Qi, Y.; Liu, S.; Grinberg, I.; Rappe, A. M.

    2016-10-01

    Barium titanate (BaTiO3) is a prototypical ferroelectric perovskite that undergoes the rhombohedral-orthorhombic-tetragonal-cubic phase transitions as the temperature increases. In this paper, we develop a classical interatomic potential for BaTiO3 within the framework of the bond-valence theory. The force field is parametrized from first-principles results, enabling accurate large-scale molecular dynamics (MD) simulations at finite temperatures. Our model potential for BaTiO3 reproduces the temperature-driven phase transitions in isobaric-isothermal ensemble (N P T ) MD simulations. This potential allows for the analysis of BaTiO3 structures with atomic resolution. By analyzing the local displacements of Ti atoms, we demonstrate that the phase transitions of BaTiO3 exhibit a mix of order-disorder and displacive characters. Besides, from a detailed observation of structural dynamics during phase transition, we discover that the global phase transition is associated with changes in the equilibrium value and fluctuations of each polarization component, including the ones already averaging to zero, Contrary to the conventional understanding that temperature increase generally causes bond-softening transition, the x -polarization component (the one which is polar in both the orthorhombic and the tetragonal phases) exhibits a bond-hardening character during the orthorhombic-to-tetragonal transition. These results provide further insight about the temperature-driven phase transitions in BaTiO3.

  3. Synthesis and luminescent properties of novel BaGd2O4:Eu3+ scintillating phosphor.

    PubMed

    Sun, Xin-Yuan; Wang, Wen-Feng; Sun, Shou-Qiang; Lin, Liang-Wu; Li, De-Yi; Zhou, Ling-Ping

    2013-01-01

    BaGd2-x O4:xEu(3+) and Ba1-y Gd1.79-2y Eu0.21 Na3y O4 phosphors were synthesized at 1300°C in air by conventional solid-state reaction method. Phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence excitation (PLE) spectra, photoluminescence (PL) spectra and thermoluminescence (TL) spectra. Optimal PL intensity for BaGd2-x O4 :xEu(3+) and Ba1-y Gd1.79-2y Eu0.21 Na3y O4 phosphors at 276 nm excitation were found to be x = 0.24 and y = 0.125, respectively. The PL intensity of Eu(3+) emission could only be enhanced by 1.3 times with incorporation of Na(+) into the BaGd2 O4 host. Enhanced luminescence was attributed to the flux effect of Na(+) ions. However, when BaGd2 O4:Eu(3+) phosphors were codoped with Na(+) ions, the induced defects confirmed by TL spectra impaired the emission intensity of Eu(3+) ions.

  4. 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.

  5. 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.

  6. Electrochemical impedance spectroscopy of BaCeO 3 modified by Ti and Y

    NASA Astrophysics Data System (ADS)

    Pasierb, P.; Wierzbicka, M.; Komornicki, S.; Rekas, M.

    Barium cerate exhibits high protonic conductivity, especially when modified by trivalent dopant such as Y, Yb, Nd, Sm or Dy. Unfortunately, the poor chemical stability in the presence of CO 2 is the main disadvantage of this material. One of the possible approach to get the stable protonic conductor is the preparation of solid solutions. For example, doping of BaCeO 3 with Zr leads to the improvement of the chemical stability, but the electrical properties are simultaneously corrupted. In the present work the influence of Ti, per analogy to Zr, and Y dopants on electrical properties of BaCeO 3 was investigated using the electrochemical impedance spectroscopy (EIS) technique. BaCe 1- xTi xO 3- δ (0 ≤ x ≤ 0.3) and Ba(Ce 0.95Ti 0.05) 0.95Y 0.05O 3- δ solid electrolytes were prepared by solid-state reaction method. It was found that the changes of electrical properties due to the introduction of Ti into the BaCeO 3 lattice is caused predominantly by the modification of the grain boundary properties. The Ti doping leads to the substantial decrease of grain boundary electrical conductivity, comparing to undoped material. The introduction of yttrium dopant to the BaCe 0.95Ti 0.05O 3 lattice has the opposite effect. The total electrical conductivity increases, due to significant modification of grain boundary electrical properties.

  7. Enhanced resistive memory in Nb-doped BaTiO3 ferroelectric diodes

    NASA Astrophysics Data System (ADS)

    Jin, Qiao; Zheng, Chunyan; Zhang, Yongcheng; Lu, Chaojing; Dai, Jiyan; Wen, Zheng

    2017-07-01

    In this study, we report on enhanced resistive memory in BaTiO3-based ferroelectric diodes due to the doping of donors. A large ON/OFF current ratio of ˜2000, about two orders of magnitude higher than that of Au/BaTiO3/SrRuO3, is achieved in a Au/Nb:BaTiO3/SrRuO3 diode at room temperature. This can be ascribed to the enhanced ferroelectric-modulation on the potential barrier at the Nb:BaTiO3/SrRuO3 interface associated with the (NbTi4+ 5 +) . donors, which gives rise to an efficient control of device transport between a bulk-limited current in the ON state and an interface-limited Schottky emission in the OFF state. In contrast, the resistance switching is suppressed in a Au/Fe:BaTiO3/SrRuO3 device since the (FeTi4+ 3 +) ' acceptors suppress semiconducting character of the BaTiO3 thin film and make the polarization-modulation of the band diagram negligible. The present work facilitates the design of high-performance resistive memory devices based on ferroelectric diodes with controllable charged defects.

  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. Multi-Colony Calibrations of Coral Ba/Ca With a Contemporaneous In Situ Seawater Barium Record

    NASA Astrophysics Data System (ADS)

    LaVigne, M.; Matthews, K. A.; Grottoli, A. G.; Palardy, J.; Sherrell, R. M.

    2014-12-01

    The coral skeleton barium to calcium ratio (Ba/Cacoral), a proxy for seawater barium concentration (BaSW), has been interpreted as an upwelling tracer based on the "nutrient like" depth profile of BaSW. However, terrestrial runoff and differences between the vertical distribution of BaSW and that of the major nutrients in the upper water column can compromise the reliability of Ba/Cacoral as an upwelled nutrient proxy in some coastal locations. For example, a 6-month time series record of BaSW, SST, SSS, and surface nutrients in the Gulf of Panamá shows that maximum seasonal inputs from terrestrial runoff occur during the upwelling minimum. In contrast to nutrients, BaSW variations resulting from upwelling are overwhelmed by the runoff influence at this location. High resolution Ba/Cacoral records from multiple colonies of Porites lobata, Pavona gigantea, and Pavona clavus corals growing during this period record the nearly two-fold runoff-induced change in BaSW in Gulf of Panamá surface waters as an ~20-70% increase in skeletal Ba/Ca, providing an opportunity to calibrate the Ba proxy with a contemporaneous BaSW record. Compiling the Ba/Cacoral records from three co-located colonies of each species into taxa-specific composite regressions reveal statistically significant correlations with the BaSW time-series (r2=0.7; p <0.001). The application of the Pavona clavus calibration to a previously published Galapágos Ba/Cacoral record and offsets in regression variables between taxa demonstrate the necessity of using taxa-specific calibrations for quantitative BaSW reconstructions. Similar studies using longer high-resolution multi-colony records could further our understanding of intercolony-reproducibility and reduce the uncertainty in the regressions. These results support the application of Ba/Cacoral to reconstruct past changes in BaSW and underscore the value of combining multiple skeletal proxies to provide a complete picture of surface water biogeochemistry.

  10. Synthesis of Y1Ba2Cu3O(sub x) superconducting powders by intermediate phase reaction

    NASA Astrophysics Data System (ADS)

    Moore, C.; Fernandez, J. F.; Recio, P.; Duran, P.

    1990-04-01

    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.

  11. 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.

  12. Betulinic acid derivative BA5, a dual NF-kB/calcineurin inhibitor, alleviates experimental shock and delayed hypersensitivity.

    PubMed

    Meira, Cássio Santana; Espírito Santo, Renan Fernandes do; Dos Santos, Tatiana Barbosa; Orge, Iasmim Diniz; Silva, Dahara Keyse Carvalho; Guimarães, Elisalva Teixeira; Aragão França, Luciana Souza de; Barbosa-Filho, José Maria; Moreira, Diogo Rodrigo Magalhães; Soares, Milena Botelho Pereira

    2017-09-09

    Betulinic acid (BA) is a naturally occurring triterpenoid with several biological properties already described, including immunomodulatory activity. Here we investigated the immunomodulatory activity of eight semi-synthetic amide derivatives of betulinic acid. Screening of derivatives BA1-BA8 led to the identification of compounds with superior immunomodulatory activity than BA on activated macrophages and lymphocytes. BA5, the most potent derivative, inhibited nitric oxide and TNFα production in a concentration-dependent manner, and decreased NF-κB activation in Raw 264.7 cells. Additionally, BA5 inhibited the proliferation of activated lymphocytes and the secretion of IL-2, IL-4 IL-6, IL-10, IL-17A and IFNɣ, in a concentration-dependent manner. Flow cytometry analysis in lymphocyte cultures showed that treatment with BA5 induces cell cycle arrest in pre-G1 phase followed by cell death by apoptosis. Moreover, BA5 also inhibited the activity of calcineurin, an enzyme that plays a critical role in the progression of cell cycle and T lymphocyte activation. BA5 has a synergistic inhibitory effect with dexamethasone on lymphoproliferation, showing a promising profile for drug combination. Finally, we observed immunosuppressive effects of BA5 in vivo in mouse models of lethal endotoxemia and delayed type hypersensitivity. Our results reinforce the potential use of betulinic acid and its derivatives in the search for potent immunomodulatory drugs. Copyright © 2017. Published by Elsevier B.V.

  13. 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

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

    NASA Astrophysics Data System (ADS)

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

    2017-05-01

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

  15. 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.

  16. On the quasi-1D magnetic behavior of Ba 2MnCoAl 2F 14, Ba 2MnCuAl 2F 14 and related compounds

    NASA Astrophysics Data System (ADS)

    le Lirzin, A.; Darriet, J.; Georges, R.; Soubeyroux, J. L.

    1992-02-01

    Two new fluorides Ba 2MnCoAl 2F 14 and Ba 2MnCoAl 2F 14, isostructural with the natural compound usovite Ba 2CaMgAl 2F 14, have been synthesized. The nuclear structures of both compounds, refined from neutron diffraction data, give evidence for strongly disordered bimetallic chains MnCu or MnCo along the b-axis: two new theoretical treatments are suggested in order to account for the magnetic behavior of each compound but, due to their intrinsic limitations, they are in fact applied here to solid solutions between the parent compound and BaMnAlF 7, namely Ba 2Mn 1+ yCu 1- yAl2F14 and Ba 2Mn1+ yCo1- yAl 2F 14, leading to a rather good agreement with the measured values of the susceptibilities.

  17. 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.

  18. Controlled orientation of molecular-beam-epitaxial BaTiO3 on Si(001) using thickness engineering of BaTiO3 and SrTiO3 buffer layers

    NASA Astrophysics Data System (ADS)

    Hsu, Min-Hsiang Mark; Van Thourhout, Dries; Pantouvaki, Marianna; Meersschaut, Johan; Conard, Thierry; Richard, Olivier; Bender, Hugo; Favia, Paola; Vila, Maria; Cid, Rosalia; Rubio-Zuazo, Juan; Castro, German R.; Van Campenhout, Joris; Absil, Philippe; Merckling, Clement

    2017-06-01

    Monolithically integrating BaTiO3 on silicon substrates has attracted attention because of the wide spectrum of potential novel applications ranging from electronics to photonics. For optimal device performance, it is important to control the BaTiO3 domain orientation during thin film preparation. Here, we use molecular beam epitaxy to prepare crystalline BaTiO3 on Si(001) substrates using a SrTiO3 buffer layer. A systematic investigation is performed to understand how to control the BaTiO3 domain orientation through the thickness engineering of the SrTiO3 buffer layer and the BaTiO3 layer itself. This provides different possibilities for obtaining a given BaTiO3 orientation as desired for a specific device application.

  19. Improved computed radiography image quality from a BaFl:Eu photostimulable phosphor plate.

    PubMed

    Nakano, Yasushi; Gido, Tomonori; Honda, Satoshi; Maezawa, Akihiro; Wakamatsu, Hideaki; Yanagita, Takafumi

    2002-04-01

    Recent advances in the design of photostimulable phosphor (PSP) plates for computed radiography (CR) systems have made it possible to manufacture plates made of BaFI:Eu phosphor material in the cassette form. The image quality of this plate, six BaF(Br,I):Eu plates, and one BaFBr:Eu plate were evaluated in terms of presampling modulation transfer function (MTF), normalized Wiener spectra (WSN), and detective quantum efficiency (DQE). Compared with the best-performing BaF(Br,I):Eu plate, the BaFI:Eu plate provided DQE that was higher, at spatial frequencies of 0.5, 1.0, and 2.0 cycles/mm, by 12% (21.8 versus 19.4), 13% (18.8 versus 16.7), and 11% (12.0 versus 10.8), respectively. Since presampling MTF values of the two plates were comparable, the BaFI:Eu plate's higher DQE is attributable to total WSN conversely being lower by 17% [8.65 x 10(-5) (mm2) versus 10.38 x 10(-5) (mm2)], 17% [5.85 x 10(-5) (mm2) versus 7.03 x 10(-5) (mm2)], and 12% [2.82 x 10(-5) (mm2) versus 3.19 x 10(-5) (mm2)] at the specified frequencies, respectively, primarily due to the contribution of x-ray quantum WSN. This jibes with the high x-ray absorption provided by the 27%-higher x-ray attenuation coefficients (7.54 versus 6.07, at 60 KeV) that BaFI offers over BaF(Br(0.85),I(0.15)), a result of the high atomic number of BaFI's exclusively iodine halide content. The results were consistent with earlier studies of several of these same plates and indicate that BaFI:Eu is a promising avenue to lower image noise and higher overall CR system image quality.

  20. High-pressure BaCrO{sub 3} polytypes and the 5H–BaCrO{sub 2.8} phase

    SciTech Connect

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

    2015-12-15

    Polytypism of BaCrO{sub 3} perovskites has been investigated at 900–1100 °C and pressures up to 22 GPa. Hexagonal 5H, 4H, and 6H perovskites are observed with increasing pressure, and the cubic 3C perovskite (a=3.99503(1) Å) is observed in bulk form for the first time at 19–22 GPa. An oxygen-deficient material with limiting composition 5H–BaCrO{sub 2.8} is synthesised at 1200 °C under ambient pressure. This contains double tetrahedral Cr{sup 4+} layers and orders antiferromagnetically below 260 K with a (0 0 1/2) magnetic structure. - Graphical abstract: Hexagonal 5H, 4H, and 6H perovskites polytypes of BaCrO{sub 3} are observed with increasing pressure and the cubic 3C perovskite is stabilised in bulk form for the first time at 19–22 GPa. Oxygen-deficient 5H–BaCrO{sub 2.8} synthesised at ambient pressure contains double tetrahedral Cr{sup 4+} layers and orders antiferromagnetically below 260 K with a (0 0 1/2) magnetic structure.

  1. Synthesis and crystal structure of new layered BaNaSc(BO 3) 2 and BaNaY(BO 3) 2 orthoborates

    NASA Astrophysics Data System (ADS)

    Seryotkin, Yurii V.; Bakakin, Vladimir V.; Kokh, Aleksandr E.; Kononova, Nadezhda G.; Svetlyakova, Tatyana N.; Kokh, Konstantin A.; Drebushchak, Tatyana N.

    2010-05-01

    Crystals of two new layered BaNaSc(BO 3) 2 ( I) and BaNaY(BO 3) 2 ( II) orthoborates are grown from the melt-solution by the spontaneous crystallization onto the platinum loop. Single crystal X-ray analysis showed that the compounds are isostructural with the space group R3¯, a=5.23944(12) and 5.3338(2) Å, and c=34.5919(11) and 35.8303(19) Å for I and II, respectively, Z=6. The distinctive feature of the structure is the close-packed composite anion-cation (Ba,Na)(BO 3) layers. The layers are combined into the base building packages of two types: { M3+[Ba 2+(BO 3) 3-] 2} + and { M3+[Na +(BO 3) 3-] 2} -, where M is Sc or Y. Neutral-charge two-package (four-layer) blocks are stacked by the rhombohedral principle into twelve layers of the cubic packing.

  2. Effect of divalent Ba cation substitution with Sr on coupled 'multiglass' state in the magnetoelectric multiferroic compound Ba3NbFe3Si2O14.

    PubMed

    Rathore, Satyapal Singh; Vitta, Satish

    2015-05-19

    (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.

  3. Multilayer pinning in a-axis-oriented EuBa2Cu3O7/PrBa2Cu3O7 superconducting superlattices

    NASA Astrophysics Data System (ADS)

    Martin, J. I.; Velez, M.; Vicent, J. L.

    1995-08-01

    a-axis EuBa2Cu3O7/PrBa2Cu3O7 superlattices and a-axis films have been grown by dc sputtering to study the interplay between the natural material anisotropy (Cu-O planes) and the artificial layered structure (PrBa2Cu3O7 layers). These a-axis-oriented superlattices are unique because, in comparison with c-axis superlattices, they allow one to separate both effects: in c-axis multilayers Cu-O planes and the artificial layers are parallel whereas in a-axis multilayers the intrinsic and the artificial layers are perpendicular to each other. When B is parallel to the substrate plane, the superlattices show an enhancement of the pinning force in comparison with the behavior of the films that is controlled by the EuBa2Cu3O7 layer thickness. If B is perpendicular to the substrate plane, the flux motion presents a log B dependence of the activation energy up to at least, 40-unit-cell-thick layers.

  4. Electrical properties of ferroelectric BaTi{sub 2}O{sub 5} and dielectric Ba{sub 6}Ti{sub 17}O{sub 40} ceramics

    SciTech Connect

    Beltran, Hector; Gomez, Beatriz; Maso, Nahum; Cordoncillo, Eloisa; Escribano, Purificacion; West, Anthony R.

    2005-04-15

    Single phase powders of BaTi{sub 2}O{sub 5} and Ba{sub 6}Ti{sub 17}O{sub 40} were made by a sol-gel method with final heating at 1100-1200 deg. C. Ceramic samples were prepared and fired at temperatures in the range 1100-1300 deg. C. Both sets were highly insulating, with conductivities of, e.g., 10{sup -6}-10{sup -7} S cm{sup -1} at 600 deg. C and activation energies for conduction in the range 1.75-1.86 eV. BaTi{sub 2}O{sub 5} compositions are ferroelectric with a permittivity maximum dependent on firing conditions: {epsilon}{sub max}{sup '}=122 at 450 deg. C on firing at 1100 deg. C; and {epsilon}{sub max}{sup '}=130 at 475 deg. C on firing at 1225 deg. C. Ba{sub 6}Ti{sub 17}O{sub 40} is a dielectric with {epsilon}{sup '}{approx}57-55 over the range 40-400 deg. C.

  5. Second Phase (BaGeO3, BaSiO3) Nanocolumns in YBa2Cu3O7-x Films

    NASA Astrophysics Data System (ADS)

    Varanasi, C. V.; Reichart, J.; Burke, J.; Wang, H.; Susner, M.; Sumption, M.; Barnes, P. N.

    2010-04-01

    YBa2Cu3O7-x (YBCO) films with BaGeO3 (BGeO), BaSiO3 (BSiO) second phase additions were processed by pulsed laser deposition. Sectored targets with BGO or BSiO wedges as well as pre-mixed targets of YBCO, BGeO or BSiO with appropriate compositions were used to deposit YBCO+BGeO and YBCO+BSiO films on (100) single crystal LaAlO3 substrates. The cross-sectional transmission electron micrographs showed the presence of 20 nm diameter nanocolumns in the YBCO films of both the compositions. However, the critical transition temperature (Tc) of the films was found to significantly decrease. As a result, the critical current density (Jc) in applied magnetic fields was suppressed. The YBCO+BGeO and YBCO+BSiO films made with lower concentrations of additions showed slight improvement in Tc indicating that the substitution of Ge and Si in the lattice is possibly responsible for the Tc depression. This study shows that in addition to the ability to form nanocolumns, the chemical compatibility of BaSnO3 (BSO) and BaZrO3 (BZO) as observed in YBCO+BSO and YBCO+BZO is critical to process high Jc YBCO films.

  6. The Scale Formation of Barite (BaSO4) from Laminar Flowing Water in The Presence of Tartaric Acid and Ba2+ Concentration Variation of Solution

    NASA Astrophysics Data System (ADS)

    Fatra, F.; Ivanto, G.; Dera, N. S.; Muryanto, S.; Bayuseno, A. P.

    2017-05-01

    The barite (BaSO4) scale is a mineral deposit that can be precipitated during the process of drilling oil and gas in the offshore. Deposite scale in pipes can cause a narrowing of the diameter of pipes, and can reduce water flowing in the pipe. The aim of this study is to investigation the effect of the tartaric acid additive and Ba2+ concentration on the growth o the scale formation of barite in the laminar flow of the piping system. Solution forming barite crystal was prepared by mixing equimolar solutions of barium chloride (BaCl2) and sodium sulfate (Na2SO4) with concentration variations of Ba2+ of 3000, 3500, 4000, 4500, and 5000 ppm. The flow rate of solution is 40 ml/min at temperature of 50 °C. Various concentrations of tartaric acid (C4H6O6) of 0 ppm, 5 ppm and 10 ppm were added to the solutions. The formation of barite from the solution was observed by ion conductivity measurement. The obtained barite crystals before and after adding tartaric acid were dried and characterized by using SEM/EDX for morphology and elemental analysis, and XRD for phase identification. The SEM results show that the morphology of the crystals are star-like particles, while XRD analysis confirmed that the barite crystals were produced during the experiments are high purity. Moreover, the tartaric acid can inhibit the crystal growth of barite.

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

    PubMed

    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

    2015-03-14

    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.

  8. Malignant intraperitoneal mesothelioma-Başkent University experience

    PubMed Central

    Macuks, Ronalds; Özdemir, Halis; Dursun, Polat; Özen, Özlem Işıksaçan; Haberal, Nihan; Ayhan, Ali

    2011-01-01

    Objective To evaluate diagnostic and treatment results of malignant intraperitoneal mesothelioma in one setting. Materials and Method: 12 patients treated for malignant peritoneal mesothelioma from January 2007 to June 2009 in Başkent University Ankara Hospital, Department of Gynaecology and Obstetrics were evaluated. In a retrospective observational study design tumour stage, grade, differentiation, time from first symptoms, pleural involvement, peritoneal cancer index, surgical cytoreduction, chemotherapeutic regimen, number of cycles, disease free survival and overall survival were evaluated. Disease free survival, overall survival, time until first symptoms were researched. Results The main presenting symptom was abdominal distension. Primary cytoreductive surgery followed by chemotherapy was performed in 9 patients. In 6 patients completeness of cytoreductive score below 2 was achieved. As a first line chemotherapy the most often used was cisplatin in combination with pemetrexed. Themean time from first symptoms until the diagnosis was 1.9 months. Disease free survival of 4.4±1.0 months after completing particular treatment and overall 1-year survival of 85.7 % was observed. No correlations between first symptoms (0.27, p=0.52), time until the diagnosis (−0.29, p=0.44) and overall survival were observed. Similarly, correlations between peritoneal cancer index (0.25, p=0.67), prior surgical score (−.45, p=0.37), completeness of cytoreduction score (0.61, p=0.27) and overall survival were not observed. Conclusions Because of the low number of patients and different treatment approaches data from a particular patient setting are inconclusive, but from the literature there is evidence that patients with malignant intraperitoneal mesothelioma should undergo optimal cytoreduction and receive a combination of cisplatin and pemetrexed as a first line chemotherapy for intravenous or cisplatin in different chemotherapy regimens using the intraperitoneal

  9. 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.

  10. The effect of interface on the electrical properties of (Ba, Sr)TiO3 adopting the perovskite electrodes

    NASA Astrophysics Data System (ADS)

    Kim, Boum-Seock; Oh, Se-Hoon; Son, Seung-Young; Park, Kyung-Woong; Choi, Duck-Kyun; Dai, Z. R.; Ohuchi, Fumio S.

    2000-05-01

    Perovskite type conducting materials (Ca, Sr)RuO3 and (Ba, Sr)RuO3 were prepared by rf magnetron sputtering as bottom electrodes for (Ba, Sr)TiO3 thin film capacitors. The crystallinity, interface property, and electrical properties of the (Ba, Sr)TiO3 capacitor applying the perovskite oxide electrodes were investigated. The interface between the dielectric and the electrode were analyzed by high-resolution electron microscopy and Auger electron spectroscopy. The interface had a marked effect on the electrical properties of the (Ba, Sr)TiO3 thin films. Dielectric constant for the (Ba, Sr)TiO3 had considerable dependence on the thickness of interfacial layer. The leakage current density of the capacitor was sensitive not only to the structural match but also to the chemical match between (Ba, Sr)TiO3 and the electrode.

  11. Novel perovskite-related barium tungstate Ba 11W 4O 23

    NASA Astrophysics Data System (ADS)

    Hong, Seung-Tae

    2007-11-01

    Ba 11W 4O 23 was synthesized at 1300 °C, followed by quenching with liquid nitrogen. The crystal structure, which was known to be cryolite-related but has remained unclear, was initially determined by single-crystal X-ray diffraction for the isostructural Ru-substituted compound Ba 11(W 3.1Ru 0.9)O 22.5, which was discovered during exploratory synthesis in the Ba-Ru-O system. The structure of Ba 11W 4O 23 was refined by a combined powder X-ray and neutron Rietveld method ( Fd-3 m, a=17.1823(1) Å, Z=8, Rp=3.09%, Rwp=4.25%, χ2=2.8, 23 °C). The structure is an example of A-site vacancy-ordered 4×4×4 superstructure of a simple perovskite ABO 3, and it may be written as (Ba 1.75□ 0.25)BaWO 5.75□ 0.25, emphasizing vacancies on both metal and anion sites. The local structure of one of two asymmetric tungsten ions is the WO 6 octahedron, typical of perovskite. The other tungsten, however, is surrounded by oxygen and anionic vacancies statistically distributed over three divided sites to form 18 partially occupied oxygen atoms (˜30% on average), represented as WO 18/3. The A-site cation-vacancies are ordered at the 8a ( {1}/{8}, {1}/{8}, {1}/{8}) site in between adjoining WO 18/3 polyhedra which form 1-D arrangements along [110] and equivalent directions. In situ high-temperature XRD data have shown that the quenched Ba 11W 4O 23 at room temperature is isostructural to the high-temperature phase at 1100 °C.

  12. 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.

  13. Thermal expansion and structural complexity of Ba silicates with tetrahedrally coordinated Si atoms

    NASA Astrophysics Data System (ADS)

    Gorelova, Liudmila A.; Bubnova, Rimma S.; Krivovichev, Sergey V.; Krzhizhanovskaya, Maria G.; Filatov, Stanislav K.

    2016-03-01

    Thermal expansion of Ba silicates with tetrahedrally coordinated Si atoms in the temperature range of 25-1100 °C had been studied by high-temperature X-ray powder diffraction. The volume thermal expansion coefficients (TECs) are in the range 41-50×10-6 °C-1 with an average value of <αV > = 45 ×10-6 °C-1. In the structures with chain and layered silicate anions, thermal expansion is anisotropic: the direction of maximal TEC is parallel to the extension of the zweier chains of silicate tetrahedra, which are strained owing to the interactions with Ba2+. The strain is released during thermal expansion due to the increasing effective size of Ba2+ induced by thermal vibrations. Information-theoretic analysis of the structural and topological complexities of Ba silicates indicates that their structural complexity is a function of the topological complexity of their silicate anions. The latter displays a non-linear behaviour with increasing SiO2 content (=the increasing degree of polymerization and increasing dimensionality): it starts from simple topologies, reaches a maximum at topologies of intermediate complexity, and ends up at simple topologies again. The specificity of the interactions of Ba2+ with the silicate anions results in higher complexity of high-temperature α-BaSi2O5 compared to that of low-temperature β-BaSi2O5. This uncommon behaviour may be explained by the vibrational advantages provided by flatter and more complex silicate layers in the α-phase, which overcome negative differences in configurational entropies of the two modifications apparent in the differences of their structural Shannon information.

  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. 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.

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

    PubMed

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

    2016-03-01

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

  17. 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.

  18. Stabilisation des phases monocristallines quadratique et cubique dans BaTiO3

    NASA Astrophysics Data System (ADS)

    Amami, J.; Goutaudier, C.; Trabelsi-Ayadi, M.; Boulon, G.

    2004-12-01

    Single crystals of Ba1-xYbxTiO3 and Ba1-xSrxTiO3 with tetragonal structure were grown by the floating zone (FZ) method using an LHPG (Laser Heated Pedestal Growth) technique. The grown crystals, typically 1 mm in diameter and 8 mm in length, were yellowish transparent. Substitution of more than 2.5 at % Sr for Ba in BaTiO3 and addition of 3 to 5 at % Ln (Ln= Yb, Eu), were effective in preventing the formation of the hexagonal phase. The Eu3+ emission spectra recorded at room temperature demonstrate a significant intensity enhancement of the 5D0 → 7F1 magnetic dipolar transition compared to the 5D0 → 7F2 electric dipolar transition. Les fibres monocristallines de Ba1-xYbxTiO3 et Ba1-xSrxTiO3 de structure quadratique ont été préparées par la méthode de la zone flottante (FZ) en utilisant la technique LHPG (Laser Heated Pedestal Growth). Les échantillons élaborés, de dimensions 1mm x 8 mm, sont jaunâtres et transparentes. La substitution du baryum par plus de 2,5 mol% de Sr dans BaTiO3 et le dopage de 3 à 5 mol% de Ln (Ln = Yb, Eu) évitent la formation de la phase hexagonale. Le spectre d’émission de Eu3+ enregistré à température ambiante montre le changement de structure traduit par la forte intensité de la transition dipolaire magnétique 5D0 → 7F1 comparée à celle de la transition dipolaire électrique 5D0 → 7F2.

  19. Improvement of electron mobility in La:BaSnO{sub 3} thin films by insertion of an atomically flat insulating (Sr,Ba)SnO{sub 3} buffer layer

    SciTech Connect

    Shiogai, Junichi Nishihara, Kazuki; Sato, Kazuhisa; Tsukazaki, Atsushi

    2016-06-15

    One perovskite oxide, ASnO{sub 3} (A = Sr, Ba), is a candidate for use as a transparent conductive oxide with high electron mobility in single crystalline form. However, the electron mobility of films grown on SrTiO{sub 3} substrates does not reach the bulk value, probably because of dislocation scattering that originates from the large lattice mismatch. This study investigates the effect of insertion of bilayer BaSnO{sub 3} / (Sr,Ba)SnO{sub 3} for buffering this large lattice mismatch between La:BaSnO{sub 3} and SrTiO{sub 3} substrate. The insertion of 200-nm-thick BaSnO{sub 3} on (Sr,Ba)SnO{sub 3} bilayer buffer structures reduces the number of dislocations and improves surface smoothness of the films after annealing as proved respectively by scanning transmission electron microscopy and atomic force microscopy. A systematic investigation of BaSnO{sub 3} buffer layer thickness dependence on Hall mobility of the electron transport in La:BaSnO{sub 3} shows that the highest obtained value of mobility is 78 cm{sup 2}V{sup −1}s{sup −1} because of its fewer dislocations. High electron mobility films based on perovskite BaSnO{sub 3} can provide a good platform for transparent-conducting-oxide electronic devices and for creation of fascinating perovskite heterostructures.

  20. Study of the structural, electronic, and magnetic properties of the barium-rich iron(IV) oxides, Ba(2)FeO(4) and Ba(3)FeO(5).

    PubMed

    Delattre, James L; Stacy, Angelica M; Young, Victor G; Long, Gary J; Hermann, Raphaël; Grandjean, Fernande

    2002-06-03

    Crystals of Ba(2)FeO(4) and Ba(3)FeO(5), grown from a "self-sealing" KOH-Ba(OH)(2) flux, have been characterized by single-crystal X-ray diffraction, Mössbauer spectroscopy, and magnetic measurements. Ba(2)FeO(4) forms nonmerohedral twinned crystals with the monoclinic space group P2(1)/n, a = 6.034(2) A, b = 7.647(2) A, c = 10.162(3) A, beta = 92.931(6) degrees, and Z = 4. Ba(3)FeO(5) crystallizes in the orthorhombic space group Pnma, with a = 10.301(1) A, b = 8.151(1) A, c = 7.611(1) A, and Z = 4. While both compounds feature discrete FeO(4)(4-) tetrahedra, the anion found in Ba(2)FeO(4) has shorter Fe-O bonds and is significantly distorted relative to the Ba(3)FeO(5) anion. An iron valence of 4+ was confirmed by magnet susceptibility measurements and by the low-temperature isomer shifts of -0.152 and -0.142 mm/s relative to alpha-iron for Ba(2)FeO(4) and Ba(3)FeO(5), respectively.