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Sample records for prerequisite cr aucc

  1. Commentary: Prerequisite Knowledge

    Science.gov (United States)

    Taylor, Ann T. S.

    2013-01-01

    Most biochemistry, genetics, cell biology, and molecular biology classes have extensive prerequisite or co-requisite requirements, often including introductory chemistry, introductory biology, and organic chemistry coursework. But what is the function of these prerequisites? While it seems logical that a basic understanding of biological and…

  2. On Prerequisites of Interpreters

    Institute of Scientific and Technical Information of China (English)

    范文

    2006-01-01

    Interpreters are invariably playing a crucial role in international affairs. Those who regularly read pictorials or watch TV news programs know best why interpreters are always placed between two leaders. That is because interpreters are indispensable if any two VIPs aim to achieve further understanding, to eliminate bilateral distrust or even establish alliance with each other, a fact may partly account for why so many students are swarming into translation schools. Are they able to become interpreters? What are the prerequisites for an interpreter? This article will, taking into operative factors as complete as possible, provide a basic framework under which prerequisites of interpreters are structured.

  3. Arithmetic: Prerequisite to Algebra?

    Science.gov (United States)

    Rotman, Jack W.

    Drawing from research and observations at Lansing Community College (Michigan) (LCC), this paper argues that typical arithmetic courses do little to prepare students to master algebra, and proposes an alternative set of arithmetic skills as actual prerequisites to algebra. The first section offers a description of the algebra sequence at LCC,…

  4. Lack of Set Theory Relevant Prerequisite Knowledge

    Science.gov (United States)

    Dogan-Dunlap, Hamide

    2006-01-01

    Many students struggle with college mathematics topics due to a lack of mastery of prerequisite knowledge. Set theory language is one such prerequisite for linear algebra courses. Many students' mistakes on linear algebra questions reveal a lack of mastery of set theory knowledge. This paper reports the findings of a qualitative analysis of a…

  5. Advanced prerequisite for E-infinity theory

    Energy Technology Data Exchange (ETDEWEB)

    El Naschie, M. Saladin [Department of Physics, University of Alexandria, Alexandria (Egypt); Department of Astrophysics, Cairo University (Egypt); Department of Physics, Mansura University (Egypt)

    2006-11-15

    This is the third of a series of papers written with the primary aim of communicating necessary theoretical background knowledge required for an in-depth study of E-infinity theory. Compared to the previous two papers [El Naschie MS. Elementary prerequisites for E-infinity (Recommended background readings in nonlinear dynamics, geometry and topology). Chaos, Solitons and Fractals 2006;30(3):579-605; El Naschie MS. Intermediate prerequisites for E-infinity theory. Chaos, Solitons and Fractals 2006;30(3):622-8], the present one may be described as advanced.

  6. Understanding spermatogenesis is a prerequisite for treatment

    Directory of Open Access Journals (Sweden)

    Schulze Wolfgang

    2003-11-01

    Full Text Available Abstract Throughout spermatogenesis multiplication, maturation and differentiation of germ cells results in the formation of the male gamete. The understanding of spermatogenesis needs detailed informations about the organization of the germinal epithelium, the structure and function of different types of germ cells, endocrine and paracrine cells and mechanisms, intratesticular and extratesticular regulation of spermatogenesis. Normal germ cells must be discriminated from malformed, apoptotic and degenerating germ cells and tumor cells. Identification of the border line between normal and disturbed spermatogenesis substantiate the diagnosis of impaired male fertility. The profound knowledge of the complicate process of spermatogenesis and all cells or cell systems involved with is the prerequisite to develop concepts for therapy of male infertility or to handle germ cells in the management of assisted reproduction.

  7. Syllable division: Prerequisite to dyslexics' literacy.

    Science.gov (United States)

    Cox, A R; Hutcheson, L

    1988-01-01

    Skill in reading long words is prerequisite to dyslexics' literacy. Instant recognition of printed symbols is easy for those readers with photographic memories, but dyslexics often fail to recognize visually many long words which are actually familiar to them auditorially. Scientific, automatic, multisensory procedures for dividing longer words into easily read syllables can enable students to translate visual symbols rapidly and thereby to read, write, or spell accurately words of any length.Over one thousand dyslexics, aged seven to fifteen, guided the interdisciplinary team at Texas Scottish Rite Hospital in Dallas to develop, observe results, and test specific structured, sequential steps in working out longer words. The ten-year study (1965-1975) in the Language Laboratory of the Hospital established the Alphabetic Phonics curriculum which is now used successfully, not only in remedial groups but in regular classes of any size or age, in public and private schools in 45 states and six foreign countries.The newly-established Aylett Royall Cox Institute in Dallas prepares teachers and Master Instructors to train both students and other teachers. Comparable Alphabetic Phonics Teacher Training Centers are already established in Houston and Lubbock, Texas, in Oklahoma City, and at Columbia University Teachers College in New York.

  8. Academic Performance in MBA Programs: Do Prerequisites Really Matter?

    Science.gov (United States)

    Christensen, Donald Gene; Nance, William R.; White, Darin W.

    2012-01-01

    Many researchers have examined criteria used in Master of Business Administration (MBA) admissions decisions. However, prior research has not examined predictive ability of undergraduate prerequisite courses in core business disciplines. The authors investigated whether undergraduate prerequisite courses predicted MBA success by analyzing the…

  9. Academic Performance in MBA Programs: Do Prerequisites Really Matter?

    Science.gov (United States)

    Christensen, Donald Gene; Nance, William R.; White, Darin W.

    2012-01-01

    Many researchers have examined criteria used in Master of Business Administration (MBA) admissions decisions. However, prior research has not examined predictive ability of undergraduate prerequisite courses in core business disciplines. The authors investigated whether undergraduate prerequisite courses predicted MBA success by analyzing the…

  10. What's in a Prerequisite? A Mixed-Methods Approach to Identifying the Impact of a Prerequisite Course

    Science.gov (United States)

    Sato, Brian K.; Lee, Amanda K.; Alam, Usman; Dang, Jennifer V.; Dacanay, Samantha J.; Morgado, Pedro; Pirino, Giorgia; Brunner, Jo Ellen; Castillo, Leanne A.; Chan, Valerie W.; Sandholtz, Judith H.

    2017-01-01

    Despite the ubiquity of prerequisites in undergraduate science, technology, engineering, and mathematics curricula, there has been minimal effort to assess their value in a data-driven manner. Using both quantitative and qualitative data, we examined the impact of prerequisites in the context of a microbiology lecture and lab course pairing.…

  11. Prerequisites of the Passage to a Regime of Inflation Targeting

    Directory of Open Access Journals (Sweden)

    Mirela Minica

    2006-10-01

    Full Text Available The article synthetically presents the main prerequisites of the institutional and technical order we should consider in the context of the National Bank’s adopting a complex policy of inflation targeting.

  12. Are There Linguistic Prerequisites for Contact-Induced Language Change?

    Science.gov (United States)

    Thomason, Sarah Grey

    Observation of language change caused by language contact tend not to support theories put forth by Meillet, Jakobson, Weinreich, and others that there are linguistic prerequisites for such change. A theory of the social factors that determine what kinds of language change will take place as a result of contact begins with the recognition of two…

  13. Students' Perceptions on Intrapreneurship Education--Prerequisites for Learning Organisations

    Science.gov (United States)

    Kansikas, Juha; Murphy, Linda

    2010-01-01

    The aim of this qualitative study is to understand the prerequisites for learning organisations (LO) as perceived by university students. Intrapreneurship education offers possibilities to increase student's adaptation of learning organisation's climate and behaviour. By analysing students' perceptions, more information about learning organisation…

  14. Cognitive and Neural Prerequisites for Time in Language: Any Answers?

    Science.gov (United States)

    Gullberg, Marianne; Indefrey, Peter

    2008-01-01

    In the position article to this volume, Klein outlines a set of questions that are relevant for furthering the linguist's understanding of what the cognitive and neural prerequisites for time in language might be. He also declares a certain skepticism regarding the likelihood that new methods from other disciplines will provide answers to those…

  15. Students' Perceptions on Intrapreneurship Education--Prerequisites for Learning Organisations

    Science.gov (United States)

    Kansikas, Juha; Murphy, Linda

    2010-01-01

    The aim of this qualitative study is to understand the prerequisites for learning organisations (LO) as perceived by university students. Intrapreneurship education offers possibilities to increase student's adaptation of learning organisation's climate and behaviour. By analysing students' perceptions, more information about learning organisation…

  16. Prerequisites in behavioral science and business: opportunities for dental education.

    Science.gov (United States)

    Dunning, David G; Lange, Brian M; Madden, Robert D; Tacha, Koko K

    2011-01-01

    There is increasing pressure on recent dental school graduates to understand and successfully utilize patient management and business management strategies to run a productive dental office. Dental schools are faced with the dilemma to either add more credit hours in their already crowded curriculum or adjust predental school requirements. All fifty-nine U.S. dental schools were assessed online to determine admission requirements in the areas of behavioral science and business education. Results show that only 11.9 percent of the schools require prerequisite course work in behavioral science and no school requires prerequisite course work in business. However, 64.4 percent and 30.5 percent of schools encouraged or recommended prerequisite course work in behavioral science and business, respectively. We suggest that the dental education community involve key stakeholders to discuss the incorporation of prerequisite course work in behavioral science and business. Additional courses in these disciplines would provide dental students better backgrounds from which the dental curriculum could build a more advanced and applied perspective to better prepare students for practice.

  17. Should College Algebra be a Prerequisite for Taking Psychology Statistics?

    Science.gov (United States)

    Sibulkin, Amy E.; Butler, J. S.

    2008-01-01

    In order to consider whether a course in college algebra should be a prerequisite for taking psychology statistics, we recorded students' grades in elementary psychology statistics and in college algebra at a 4-year university. Students who earned credit in algebra prior to enrolling in statistics for the first time had a significantly higher mean…

  18. Are There Linguistic Prerequisites for Contact-Induced Language Change?

    Science.gov (United States)

    Thomason, Sarah Grey

    Observation of language change caused by language contact tend not to support theories put forth by Meillet, Jakobson, Weinreich, and others that there are linguistic prerequisites for such change. A theory of the social factors that determine what kinds of language change will take place as a result of contact begins with the recognition of two…

  19. 76 FR 14678 - Communications Unit Leader Prerequisite and Evaluation

    Science.gov (United States)

    2011-03-17

    ... the entire collection increasing from the initial reported cost of $48,840 to $49,084. Analysis Agency... Burden Cost (operating/maintaining): $18,315. COML Train the Trainer Prerequisites Verification Frequency..., or other technological collection techniques or other forms of information technology, e.g...

  20. What's in a Prerequisite? A Mixed-Methods Approach to Identifying the Impact of a Prerequisite Course.

    Science.gov (United States)

    Sato, Brian K; Lee, Amanda K; Alam, Usman; Dang, Jennifer V; Dacanay, Samantha J; Morgado, Pedro; Pirino, Giorgia; Brunner, Jo Ellen; Castillo, Leanne A; Chan, Valerie W; Sandholtz, Judith H

    2017-01-01

    Despite the ubiquity of prerequisites in undergraduate science, technology, engineering, and mathematics curricula, there has been minimal effort to assess their value in a data-driven manner. Using both quantitative and qualitative data, we examined the impact of prerequisites in the context of a microbiology lecture and lab course pairing. Through interviews and an online survey, students highlighted a number of positive attributes of prerequisites, including their role in knowledge acquisition, along with negative impacts, such as perhaps needlessly increasing time to degree and adding to the cost of education. We also identified a number of reasons why individuals do or do not enroll in prerequisite courses, many of which were not related to student learning. In our particular curriculum, students did not believe the microbiology lecture course impacted success in the lab, which agrees with our analysis of lab course performance using a previously established "familiarity" scale. These conclusions highlight the importance of soliciting and analyzing student feedback, and triangulating these data with quantitative performance metrics to assess the state of science, technology, engineering, and mathematics curricula.

  1. What’s in a Prerequisite? A Mixed-Methods Approach to Identifying the Impact of a Prerequisite Course

    Science.gov (United States)

    Sato, Brian K.; Lee, Amanda K.; Alam, Usman; Dang, Jennifer V.; Dacanay, Samantha J.; Morgado, Pedro; Pirino, Giorgia; Brunner, Jo Ellen; Castillo, Leanne A.; Chan, Valerie W.; Sandholtz, Judith H.

    2017-01-01

    Despite the ubiquity of prerequisites in undergraduate science, technology, engineering, and mathematics curricula, there has been minimal effort to assess their value in a data-driven manner. Using both quantitative and qualitative data, we examined the impact of prerequisites in the context of a microbiology lecture and lab course pairing. Through interviews and an online survey, students highlighted a number of positive attributes of prerequisites, including their role in knowledge acquisition, along with negative impacts, such as perhaps needlessly increasing time to degree and adding to the cost of education. We also identified a number of reasons why individuals do or do not enroll in prerequisite courses, many of which were not related to student learning. In our particular curriculum, students did not believe the microbiology lecture course impacted success in the lab, which agrees with our analysis of lab course performance using a previously established “familiarity” scale. These conclusions highlight the importance of soliciting and analyzing student feedback, and triangulating these data with quantitative performance metrics to assess the state of science, technology, engineering, and mathematics curricula. PMID:28232587

  2. Prerequisites for Successful Strategic Partnerships for Sustainable Building Renovation

    DEFF Research Database (Denmark)

    Jensen, Per Anker; Johansen, Jakob Berg; Thuesen, Christian

    The purpose of this paper is to identify the prerequisites for establishing successful strategic partnerships in relation to renovating buildings sustainably. Establishing strategic partnerships is in the paper seen as a potential way to make building renovation more sustainable in Denmark...... particularly in terms of reducing energy consumption and use of resources and increase productivity. However, until now we have only had a limited number of such partnerships implemented and the few examples that do exist, mostly concern the construction of new buildings. The paper is based on an investigation...... industry and analyses of two exemplary cases the paper suggests prerequisites for establishing successful strategic partnerships for sustainable building renovation. The results show that strategic partnerships are collaborations set up between two or more organizations that remain independent...

  3. PREREQUISITE PROGRAMMES IN OWN CHECKS IN STATUTORY AND VOLUNTARY LEGISLATION

    Directory of Open Access Journals (Sweden)

    E. Guidi

    2012-08-01

    Full Text Available Prerequisite Programmes approach is a requirement for implementing a correct own check plan. This new approach, born according to the European Legislation, is completely recognized by third Nation Authorities and private Inspection and Accreditation Bodies. This method is the basis to verify if an own check system is under control and to verify if corrective actions are built up to warrant hygienic production standards. The present work demonstrate that a correct own check plan is built up only by a Pre Requisites Program approach. The new UNI EN ISO 22000:2005 standard describe this concept specifying the difference between PRP and CCP.

  4. Minimal Impact of Organic Chemistry Prerequisite on Student Performance in Introductory Biochemistry

    Science.gov (United States)

    Wright, Robin; Cotner, Sehoya; Winkel, Amy

    2009-01-01

    Curriculum design assumes that successful completion of prerequisite courses will have a positive impact on student performance in courses that require the prerequisite. We recently had the opportunity to test this assumption concerning the relationship between completion of the organic chemistry prerequisite and performance in introductory…

  5. Changing health care culture: a prerequisite to improving patient safety

    Directory of Open Access Journals (Sweden)

    Azizi S

    2017-05-01

    Full Text Available Saeed Azizi, Faisal Siddiqui, Ithsham Iqbal Faculty of Medicine, St George’s Hospital Medical School, London, UKWe read the recent article by Chua et al1 with great interest. We found it thought-provoking to read how novel interventions, such as sharing errors, among the team can reduce the frequency of error recurrence in the future. We are hopeful that if such interventions were applied to other areas of health care, it would yield similar results. Having said this, we strongly believe that an important prerequisite of openness among health care workers is required for such interventions to work. View the original paper by Chua et al 

  6. Epistemological considerations on neuroimaging--a crucial prerequisite for neuroethics.

    Science.gov (United States)

    Huber, Christian G; Huber, Johannes

    2009-07-01

    Whereas ethical considerations on imaging techniques and interpretations of neuroimaging results flourish, there is not much work on their preconditions. In this paper, therefore, we discuss epistemological considerations on neuroimaging and their implications for neuroethics. Neuroimaging uses indirect methods to generate data about surrogate parameters for mental processes, and there are many determinants influencing the results, including current hypotheses and the state of knowledge. This leads to an interdependence between hypotheses and data. Additionally, different levels of description are involved, especially when experiments are designed to answer questions pertaining to broad concepts like the self, empathy or moral intentions. Interdisciplinary theoretical frameworks are needed to integrate findings from the life sciences and the humanities and to translate between them. While these epistemological issues are not specific for neuroimaging, there are some reasons why they are of special importance in this context: Due to their inferential proximity, 'neuro-images' seem to be self-evident, suggesting directness of observation and objectivity. This has to be critically discussed to prevent overinterpretation. Additionally, there is a high level of attention to neuroimaging, leading to a high frequency of presentation of neuroimaging data and making the critical examination of their epistemological properties even more pressing. Epistemological considerations are an important prerequisite for neuroethics. The presentation and communication of the results of neuroimaging studies, the potential generation of new phenomena and new 'dysfunctions' through neuroimaging, and the influence on central concepts at the foundations of ethics will be important future topics for this discipline.

  7. Minimal Impact of Organic Chemistry Prerequisite on Student Performance in Introductory Biochemistry

    OpenAIRE

    2009-01-01

    Curriculum design assumes that successful completion of prerequisite courses will have a positive impact on student performance in courses that require the prerequisite. We recently had the opportunity to test this assumption concerning the relationship between completion of the organic chemistry prerequisite and performance in introductory biochemistry. We found no statistically significant differences between average biochemistry grades or grade distribution among students with or without t...

  8. Intermediate prerequisites for E-infinity theory (Further recommended reading in nonlinear dynamics and mathematical physics)

    Energy Technology Data Exchange (ETDEWEB)

    El Naschie, M. Saladin [Department of Physics, University of Alexandria (Egypt) and Department of Astrophysics, Cairo University (Egypt) and Department of Physics, Mansura University (Egypt)]. E-mail: LTho410189@aol.com

    2006-11-15

    The paper presents an intermediate level prerequisite for understanding E-infinity theory as applied to particle physics. It is the sequel to an earlier elementary level prerequisite paper (El Naschie MS. Elementary prerequisite for E-infinity. Chaos, Solitons and Fractals 2006;30(3):579-605). The work ends with a somewhat detailed discussion of the role which a Lagrangian type formulation could play in E-infinity theory.

  9. Social Prerequisites and Outcomes of Accountable Curriculum in Higher

    Directory of Open Access Journals (Sweden)

    Mohammadreza Nili

    2010-07-01

    Full Text Available AbstractHigher education system(HES is a social institution that has long been set up to accomplish threemissions education, research and service, but during recent years entrepreneurship has been added to itsmissions. Curriculum is the most important component and subsystem of HES and has been thought of as theheart of higher education (HE, because it is the most fundamental means that provides students withknowledge, experience and skills to supply services to the society. The curriculum which can accomplishideals and missions of universities, organizational (of the university and social (of the employers and thesociety is called accountable curriculum (AC. The main goal of this research was explanation ofprerequisites and social outcomes of higher education accountable curriculum (HEAC. To do the researchdescriptive survey method was used and in order to collect the needed data interview and questionnaireinstruments were utilized.The sample of the study which the questionnaire was distributed in, included faculty members and graduatestudents of university of Isfahan, Technical University of Isfahan, and Medical University of Isfahan andalso employers and administrators of the companies of Isfahan city. The participants of the sample wereal1ocated using stratified random sampling. The questionnaire surveyed the sample's viewpoints aboutprerequisites and outcomes of the AC in the field of social services. The collected data were analyzed atdescriptive and inferential levels using SPSS. The findings of T-test revealed that the mean of the sample'sviewpoints about the explained prerequisites and outcomes had been more than the hypothetical (theoreticalmean of the population (p≤0/001. The multivariate variance analysis( MANOVA of the data showed thatthere hadn't been significant difference among viewpoints of faculties, and employers in respect ofprerequisites of HEAC, but there had been significant difference between their views about expected

  10. A Study of the Comparative Effectiveness of Zoology Prerequisites at Slippery Rock State College.

    Science.gov (United States)

    Morrison, William Sechler

    This study compared the effectiveness of three sequences of prerequisite courses required before taking zoology. Sequence 1 prerequisite courses consisted of general biology and human biology; Sequence 2 consisted of general biology; and Sequence 3 required cell biology. Zoology students in the spring of 1972 were pretest and a posttest. The mean…

  11. 14 CFR 61.35 - Knowledge test: Prerequisites and passing grades.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Knowledge test: Prerequisites and passing....35 Knowledge test: Prerequisites and passing grades. (a) An applicant for a knowledge test must have... part for the certificate or rating sought and is prepared for the knowledge test; and (2)...

  12. Academic Performance of Nursing Students: Do Prerequisite Grades and Tutoring Make a Difference?

    Science.gov (United States)

    Potolsky, Alicia; Cohen, Jayne; Saylor, Coleen

    2003-01-01

    The academic performance of first-semester nursing students who attended 5 or more (n=18) or fewer than 5 (n=19) tutorials was compared. A significant relationship was found between grades in prerequisite science courses and first-semester performance. Those who attended fewer tutorials had higher prerequisite course grades. (Contains 17…

  13. Taxonomy of literature to justify data governance as a pre-requisite for information governance

    CSIR Research Space (South Africa)

    Olaitan, O

    2016-09-01

    Full Text Available is devoted to data governance. This study chronicles extant literature to justify the position that data governance should be a prerequisite for information governance within organisations. The study argues that an information governance policy which is based...

  14. Prerequisites for Forming the Institutional Concept of the National Economy Competitiveness under Conditions of Globalization

    Directory of Open Access Journals (Sweden)

    Yaremenko Oleh L.

    2015-03-01

    Full Text Available The article attempts to prove that under conditions of globalization there have developed objective and subjective prerequisites for forming the institutional concept of the national economy. The objective prerequisites are the newest information and communication technologies, post-industrial trends and market transformation of civilization intensified by globalization. Under such conditions instability and volatility of the institutional environment both within national economies and at the international level are observed. The aggravation of the global competition between national economies actualizes the role of such institutional factors as political system, property, public administration, economic organization, culture, etc. The subjective prerequisites are related to the fact that the institutional economic theory is currently one of the leading trends in the modern world and Ukrainian economic thought. Interest in it is explained not only by the fact that it overcomes the limitations of a number of prerequisites for the mainstream, but also because it allows considering the modern economic processes in complex

  15. 75 FR 5608 - National Protection and Programs Directorate; Communications Unit Leader (COML) Prerequisite and...

    Science.gov (United States)

    2010-02-03

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND SECURITY National Protection and Programs Directorate; Communications Unit Leader (COML) Prerequisite and Evaluation AGENCY: National Protection and Programs Directorate, Department of Homeland Security. ACTION:...

  16. A systematic review of prerequisites for implementing assessment for learning in classroom practice

    NARCIS (Netherlands)

    Heitink, M.C.; Kleij, van der F.M.; Veldkamp, B.P.; Schildkamp, K.; Kippers, W.B.

    2016-01-01

    Although many researchers acknowledge that Assessment for Learning can significantly enhance student learning, the factors facilitating or hindering its implementation in daily classroom practice are unclear. A systematic literature review was conducted to reveal prerequisites needed for Assessment

  17. Minimal impact of organic chemistry prerequisite on student performance in introductory biochemistry.

    Science.gov (United States)

    Wright, Robin; Cotner, Sehoya; Winkel, Amy

    2009-01-01

    Curriculum design assumes that successful completion of prerequisite courses will have a positive impact on student performance in courses that require the prerequisite. We recently had the opportunity to test this assumption concerning the relationship between completion of the organic chemistry prerequisite and performance in introductory biochemistry. We found no statistically significant differences between average biochemistry grades or grade distribution among students with or without the organic chemistry prerequisite. However, students who had not completed the organic chemistry prerequisite before biochemistry were more likely to withdraw from the course than those who had completed the prerequisite. In contrast to the lack of correlation between performance in biochemistry and completion of organic chemistry, we observed a strong, highly significant positive relationship between cumulative GPA and the biochemistry grade. Our data suggest that excluding students without organic chemistry would have less positive impact on student success in biochemistry than would providing additional support for all students who enroll in biochemistry with a cumulative GPA below 2.5.

  18. The political economy of health promotion: part 2, national provision of the prerequisites of health.

    Science.gov (United States)

    Raphael, Dennis

    2013-03-01

    Governmental authorities of wealthy developed nations differ in their professed commitments and activity related to the provision of the prerequisites of health through public policy action. Part 1 of this article showed how nations identified as social democratic or liberal welfare states were those where such commitments are present. Nations identified as conservative or Latin welfare states were less likely to express such commitments. However, the political economy literature suggests that despite their expressed commitments to provision of the prerequisites of health, liberal welfare states fare rather poorly in implementing these commitments. The opposite is seen for conservative welfare states. Social democratic welfare states show both commitments and public policy consistent with this objective. Part 2 of this article documents the extent to which public policy activity that provides the prerequisites of health through public policy action differs among varying welfare state regimes. Despite extensive rhetoric concerning the prerequisites of health, nations identified as liberal welfare states do a rather poor job of meeting these goals and show evidence of adverse health outcomes. In contrast, social democratic welfare states fare better in providing such prerequisites--consistent with their rhetorical statements--with better health outcomes. Interestingly, conservative--and to a lesser extent Latin--nations fare well in providing the prerequisites of health despite their lack of explicit commitment to such concepts. Findings suggest that health promoters have to concern themselves with the broad strokes of public policymaking whether or not these policy activities are identified as health promotion activities.

  19. Recalling Prerequisite Material in a Calculus II Course to Improve Student Success

    Science.gov (United States)

    Mokry, Jeanette

    2016-01-01

    This article discusses preparation assignments used in a Calculus II course that cover material from prerequisite courses. Prior to learning new material, students work on problems outside of class involving concepts from algebra, trigonometry, and Calculus I. These problems are directly built upon in order to answer Calculus II questions,…

  20. Recalling Prerequisite Material in a Calculus II Course to Improve Student Success

    Science.gov (United States)

    Mokry, Jeanette

    2016-01-01

    This article discusses preparation assignments used in a Calculus II course that cover material from prerequisite courses. Prior to learning new material, students work on problems outside of class involving concepts from algebra, trigonometry, and Calculus I. These problems are directly built upon in order to answer Calculus II questions,…

  1. Prerequisites for sustainable care improvement using the reflective team as a work model.

    Science.gov (United States)

    Jonasson, Lise-Lotte; Carlsson, Gunilla; Nyström, Maria

    2014-01-01

    Several work models for care improvement have been developed in order to meet the requirement for evidence-based care. This study examines a work model for reflection, entitled the reflective team (RT). The main idea behind RTs is that caring skills exist among those who work closest to the patients. The team leader (RTL) encourages sustainable care improvement, rooted in research and proven experience, by using a lifeworld perspective to stimulate further reflection and a developmental process leading to research-based caring actions within the team. In order to maintain focus, it is important that the RTL has a clear idea of what sustainable care improvement means, and what the prerequisites are for such improvement. The aim of the present study is, therefore, to explore the prerequisites for improving sustainable care, seeking to answer how RTLs perceive these and use RTs for concrete planning. Nine RTLs were interviewed, and their statements were phenomenographically analysed. The analysis revealed three separate qualitative categories, which describe personal, interpersonal, and structural aspects of the prerequisites. In the discussion, these categories are compared with previous research on reflection, and the conclusion is reached that the optimal conditions for RTs to work, when focussed on sustainable care improvement, occur when the various aspects of the prerequisites are intertwined and become a natural part of the reflective work.

  2. 41 CFR 105-70.006 - Prerequisites for issuing a complaint.

    Science.gov (United States)

    2010-07-01

    ... Property Management Regulations System (Continued) GENERAL SERVICES ADMINISTRATION Regional Offices-General Services Administration 70-IMPLEMENTATION OF THE PROGRAM FRAUD CIVIL REMEDIES ACT OF 1986 § 105-70.006... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Prerequisites...

  3. Investigating Validity of Math 105 as Prerequisite to Math 201 among Undergraduate Students, Nigeria

    Science.gov (United States)

    Zakariya, Yusuf F.

    2016-01-01

    In this study, the author examined the validity of MATH 105 as a prerequisite to MATH 201. The data for this study was extracted directly from the examination results logic of the university. Descriptive statistics in form of correlations and linear regressions were used to analyze the obtained data. Three research questions were formulated and…

  4. Do Screencasts Help to Revise Prerequisite Mathematics? An Investigation of Student Performance and Perception

    Science.gov (United States)

    Loch, Birgit; Jordan, Camilla R.; Lowe, Tim W.; Mestel, Ben D.

    2014-01-01

    Basic calculus skills that are prerequisites for advanced mathematical studies continue to be a problem for a significant proportion of higher education students. While there are many types of revision material that could be offered to students, in this paper we investigate whether short, narrated video recordings of mathematical explanations…

  5. Do Screencasts Help to Revise Prerequisite Mathematics? An Investigation of Student Performance and Perception

    Science.gov (United States)

    Loch, Birgit; Jordan, Camilla R.; Lowe, Tim W.; Mestel, Ben D.

    2014-01-01

    Basic calculus skills that are prerequisites for advanced mathematical studies continue to be a problem for a significant proportion of higher education students. While there are many types of revision material that could be offered to students, in this paper we investigate whether short, narrated video recordings of mathematical explanations…

  6. Quality Partnership as a Contextual Prerequisite of Successful Learning of Young and Preschool-Aged Children

    Science.gov (United States)

    Ljubetic, Maja; Ercegovac, Ina Reic; Koludrovic, Morana

    2016-01-01

    The paper discusses quality partnership as a prerequisite for the functioning of the institutions of early and pre-school education and for the child's overall development and learning. Considering that child's development and learning take place in different contexts (family, educational institutions, clubs, local and wider communities), the…

  7. The political economy of health promotion: part 1, national commitments to provision of the prerequisites of health.

    Science.gov (United States)

    Raphael, Dennis

    2013-03-01

    Canada is a leader in developing health promotion concepts of providing the prerequisites of health through health-promoting public policy. But Canada is clearly a laggard in implementing these concepts. In contrast, France is seen as a nation in which health promotion concepts have failed to gain much traction yet evidence exists that France does far better than Canada in providing these health prerequisites. Such findings suggest that it is the political economy--or form of the welfare state--of a nation rather than its explicit commitments to health promotion concepts--that shape provision of the prerequisites of health. Part 1 of this article examines how health promotion rhetoric specifically concerned with provision of the prerequisites of health differs among nations identified as being either liberal, social democratic, conservative or Latin welfare states. Governing authorities of nations that are liberal or social democratic welfare states are more likely to make explicit rhetorical commitments to provision of the prerequisites of health, the conservative and Latin states less so. Part 2 of this article provides evidence however, that despite their rhetorical commitments to provision of the prerequisites of health, liberal welfare state nations fall well behind not only the social democratic nations, but also the conservative welfare states in implementing public policies that provide the prerequisites of health. The Latin welfare states express little commitment to provision of the prerequisites of health and rather limited public policy activity towards meeting this aim.

  8. Personal potential of manager as a prerequisite of realization of managerial potential of enterprise

    OpenAIRE

    Voronkova, A. E.; Kalyuzhna, N. G.

    2013-01-01

    Crucial role of management is proved in realizing the potential of enterprise management system. The essence of the concept of “managerial staff’ based on establishing key characteristics of managerial work is specified. The necessity of consideration of personal potential managers and their competencies as prerequisites of managerial capacity of the enterprise is justified. The necessity is pointed out of mastering managers’ socio-psychological instruments of influence on the staff with the ...

  9. Do screencasts help to revise prerequisite mathematics? An investigation of student performance and perception

    Science.gov (United States)

    Loch, Birgit; Jordan, Camilla R.; Lowe, Tim W.; Mestel, Ben D.

    2014-02-01

    Basic calculus skills that are prerequisites for advanced mathematical studies continue to be a problem for a significant proportion of higher education students. While there are many types of revision material that could be offered to students, in this paper we investigate whether short, narrated video recordings of mathematical explanations (screencasts) are a useful tool to enhance student learning when revisiting prerequisite topics. We report on the outcomes of a study that was designed to both measure change in student performance before and after watching screencasts, and to capture students' perception of the usefulness of screencasts in their learning. Volunteers were recruited from students enrolled on an entry module for the Mathematics Master of Science programme at the Open University to watch two screencasts sandwiched between two online calculus quizzes. A statistical analysis of student responses to the quizzes shows that screencasts can have a positive effect on student performance. Further analysis of student feedback shows that student confidence was increased by watching the screencasts. Student views on the value of screencasts for their learning indicated that they appreciated being able to watch a problem being solved and explained by an experienced mathematician; hear the motivation for a particular problem-solving approach; engage more readily with the material being presented, thereby retaining it more easily. The positive student views and impact on student scores indicate that short screencasts could play a useful role in revising prerequisite mathematics.

  10. crRNA biogenesis

    NARCIS (Netherlands)

    Charpentier, E.; Oost, van der J.; White, M.

    2013-01-01

    Mature crRNAs are key elements in CRISPR-Cas defense against genome invaders. These short RNAs are composed of unique repeat/spacer sequences that guide the Cas protein(s) to the cognate invading nucleic acids for their destruction. The biogenesis of mature crRNAs involves highly precise processing

  11. crRNA biogenesis

    NARCIS (Netherlands)

    Charpentier, E.; Oost, van der J.; White, M.

    2013-01-01

    Mature crRNAs are key elements in CRISPR-Cas defense against genome invaders. These short RNAs are composed of unique repeat/spacer sequences that guide the Cas protein(s) to the cognate invading nucleic acids for their destruction. The biogenesis of mature crRNAs involves highly precise processing

  12. Nano Cr Interlayered CrN Coatings on Steels

    Institute of Scientific and Technical Information of China (English)

    Gaoren Li; Pranav Deshpande; J. H. Li; R. Y. Lin

    2005-01-01

    CrN coated steels assisted with a nano Cr interlayer were investigated. The Cr nano-interlayers were prepared by sputter deposition with a thickness about 70-100 nm. CrN coatings were also prepared by sputter deposition on the Cr nano-interlayers. The crystal structures, microhardness, and scratch resistance of CrN/Cr coatings were determined. Results show that the Cr nano-interlayers improve scratch resistance and the microhardness of CrN coated steels. A rapid heat treatment with infrared (IR) was performed for coated specimens in the attempt to improve bonding. With IR heat treatments, the beneficial effect of the Cr nano-interlayers was clearly observed. Without the Cr nano-interlayers, severe cracks on the surface of coatings were observed after IR heat treatment. However, with a Cr interlayer, no cracks on the surface of CrN coatings were observed after the heat treatment. The scratch resistance of coatings was also affected by the Cr nano-interlayers. The scratch track was clean and showed significantly smaller amount of scratch debris for CrN coatings with Cr interlayers than those without the Cr nano-interlayers. The microhardness of coatings with the Cr nano-interlayers is higher than those without the Cr nano-interlayers after IR heat treatment. The Cr and CrN phase have been identified with X-ray diffraction analysis, and the results show that the higher the nitrogen content in the sputtering gas, the stronger the CrN peaks observed in the diffraction patterns are.

  13. Identified obstacles and prerequisites in telenurses' work environment - a modified Delphi study.

    Science.gov (United States)

    Bjorkman, Annica; Engstrom, Maria; Olsson, Annakarin; Wahlberg, Anna Carin

    2017-05-18

    Telenursing is an expanding part of healthcare, staffed with registered nurses whose work environment is typical of a call centre. Work-related stress has been shown to be a major problem in nurses' work environments and of importance to the outcome of care, patient safety, nurse job satisfaction and burnout. Today, however, we have a limited understanding of and knowledge about the work environment for telenurses. The aim of the present study is to explore and reach consensus on perceived important obstacles and prerequisites in telenurses' work environment. A modified Delphi design, using qualitative as well as quantitative data sequentially through three phases, was taken. Data were initially collected via semi-structured interviews (Phase I) and later using a web survey (Phase II-III) between March 2015 and March 2016. The findings present a consensus view of telenurses' experiences of important obstacles and prerequisites in their work environment. Central to the findings are the aspects of telenurses having a demanding work, cognitive fatigue and having no opportunity for recovery during the work shift was ranked as important obstacles. Highly ranked prerequisites for managing were being able to focus on one caller at a time, working in a calm and pleasant environment and having technical support 24/7. Managers need to enable telenurses to experience control in their work, provided with possibilities to control their work and to recover during work; shortening work time could improve their work environment. Limited possibilities to perform work might contribute to feelings of stress and inability to perform work.

  14. Clinical Governance in Primary Care; Principles, Prerequisites and Barriers: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Jaafar Sadeq Tabrizi

    2013-07-01

    Full Text Available Introduction: Primary care organizations are the entities through which clinical governance is developed at local level. To implement clinical governance in primary care, awareness about principles, prerequisites and barriers of this quality improvement paradigm is necessary. The aim of this study is to pool evidence about implementing clinical governance in primary care organizations. Data sources: The literature search was conducted in July 2012. PubMed, Web of Science, Emerald, Springerlink, and MD Consult were searched using the following MESH keywords; “clinical governance” and “primary care” Study selection: The search was limited to English language journals with no time limitation. Articles that were either quantitative or qualitative on concepts of implementing clinical governance in primary care were eligible for this study. Data extraction: From selected articles, data on principles, prerequisites and barriers of clinical governance in primary health care were extracted and classified in the extraction tables. Results: We classified our findings about principles of clinical governance in primary care in four groups; general principles, principles related to staff, patient and communication. Prerequisites were categorized in eight clusters; same as the seven dimensions of National Health System (NHS models of clinical governance. Barriers were sorted out in five categories as structure and organizing, cultural, resource, theoretical and logistical. Conclusion: Primary care organizations must provide budget holding, incentivized programs, data feedback, peer review, education, human relations, health information technology (HIT support, and resources. Key elements include; enrolled populations, an interdisciplinary team approach, HIT interoperability and access between all providers as well as patients, devolution of hospital based services into the community, inter-sectorial integration, blended payments, and a balance of

  15. Extension and Prerequisite: An Algorithm to Enable Relations Between Responses in Chatbot Technology

    Directory of Open Access Journals (Sweden)

    Abbas S. Lokman

    2010-01-01

    Full Text Available Problem statement: Artificial intelligence chatbot is a technology that makes interactions between man and machines using natural language possible. From literature, we found out that in general, chatbot are functions like a typical search engine. Although chatbot just produced only one output instead of multiple outputs/results, the basic process flow is the same where each time an input is entered, the new search will be done. Nothing related to previous output. This research is focused on enabling chatbot to become a search engine that can process the next search with the relation to the previous search output. In chatbot context, this functionality will enhance the capability of chatbot’s input processing. Approach: In attempt to augment the traditional mechanism of chatbot processes, we used the relational database model approach to redesign the architecture of chatbot in a whole as well as incorporated the algorithm of Extension and Prerequisite (our proposed algorithm. By using this design, we had developed and tested Virtual Diabetes physician (ViDi, a web-based chatbot that function in specific domain of Diabetes education. Results: Extension and prerequisite enabled relations between responses that significantly make it easier for user to chat with chatbot using the same approach as chatting with an actual human. Chatbot can give different responses from the same input given by user according to current conversation issue. Conclusion: Extension and prerequisite makes chatting with chatbot becomes more likely as chatting with an actual human prior to the relations between responses that produce a response related to the current conversation issue.

  16. Symmetry group prerequisite for E-infinity in high energy physics

    Energy Technology Data Exchange (ETDEWEB)

    El Naschie, M.S. [Department of Physics, Alexandria University (United Kingdom); KACST, Riyadh (Saudi Arabia); Department of Astrophysics, Cairo University, Cairo (Egypt)], E-mail: Chaossf@aol.com

    2008-01-15

    The work addresses the question of extending certain symplectic and exceptional Lie Symmetry groups to the realm of chaotic dynamics. Using a collection of simple examples, the technique of transfinite continuation is illustrated and various physically relevant results are obtained. The paper is intended as an elementary introduction to the use of symmetry groups in transfinite physics and as such is a sequel to a series of previous papers constituting the elementary and advanced mathematical prerequisite for a proper understanding of E-infinity theory.

  17. Pre-requisites for the formation of unusual diffusion profiles in II-VI semiconductors

    CERN Document Server

    Wolf, H; Kronenberg, J; Wagner, F; ISOLDE Collaboration

    2010-01-01

    The diffusion of the impurities Cu, Ag, Au, and Na in CdTe and CdZnTe exhibits the unusual phenomenon of uphill diffusion if the diffusion of the impurity is performed under external Cd pressure at temperatures typically in the range 700-900 K. A model is proposed that describes these concentration profiles quantitatively and yields pre-requisites for the observation of uphill diffusion. If a metal layer is evaporated onto the implanted surface, the diffusion of the impurity is strongly affected by the generation of intrinsic defects at the metal-semiconductor interface. (C) 2010 WILEY-VCH Verlag GmbH \\& Co. KGaA, Weinheim

  18. Pre-requisites for the formation of unusual diffusion profiles in II-VI semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, H.; Kronenberg, J.; Wagner, F.; Wichert, T. [Technische Physik, Universitaet des Saarlandes, Saarbruecken (Germany)

    2010-06-15

    The diffusion of the impurities Cu, Ag, Au, and Na in CdTe and CdZnTe exhibits the unusual phenomenon of uphill diffusion if the diffusion of the impurity is performed under external Cd pressure at temperatures typically in the range 700-900 K. A model is proposed that describes these concentration profiles quantitatively and yields pre-requisites for the observation of uphill diffusion. If a metal layer is evaporated onto the implanted surface, the diffusion of the impurity is strongly affected by the generation of intrinsic defects at the metal-semiconductor interface. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  19. [Quality assurance in student training. Prerequisites for DIN EN ISO 9001:2000 in teaching].

    Science.gov (United States)

    Ochsner, W; Kaiser, C; Schirmer, U

    2007-07-01

    Standards of quality assurance according to DIN EN ISO 9001:2000 have been implemented in many university hospital departments, but often teaching activities are not included. This work presents a method that allows, after having defined the various teaching activities as sub-processes of one single core process, to include the manifold teaching activities of university hospital departments into the certification process. The stepwise description of the prerequisites for including teaching activities into ISO 9001 certification is illustrated by a concrete implementation example.

  20. Chromium segregation in CoCrTa/Cr and CoCrPt/Cr thin films for longitudinal recording media

    Energy Technology Data Exchange (ETDEWEB)

    Wittig, J.E. [Vanderbilt Univ., Nashville, TN (United States); Nolan, T.P. [Komag Inc., San Jose, CA (United States); Ross, C.A. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science; Schabes, M.E. [IBM Almaden Research Center, San Jose, CA (United States); Tang, K. [IBM Storage Systems, San Jose, CA (United States); Sinclair, R. [Stanford Univ., Palo Alto, CA (United States); Bentley, J. [Oak Ridge National Lab., TN (United States)

    1998-07-01

    Analytical electron microscopy is employed to correlate Cr segregation in Co{sub 84}Cr{sub 12}Ta{sub 4}/Cr and Co{sub 76}Cr{sub 12}Pt{sub 12}/Cr films with specific microstructural features such as grain boundary mis-orientation. Energy-filtered (EFTEM) chemical maps show that Cr segregation occurs independently of the Cr underlayer, and is highly alloy dependent. The CoCrTa film contained extensive grain boundary Cr enrichment whereas EFTEM images from the CoCrPt media show homogeneous Cr distribution. No statistically significant Ta or Pt segregation was observed. EFTEM elemental maps and energy dispersive spectroscopy (EDS) indicate that grain boundary Cr segregation depends on the type of boundary. Quantitative analysis of the Cr levels using nanoprobe EDS shows that the random angle grain boundaries contain more Cr (23 +/{minus}4 at.%) than 90{degree} boundaries (17 +/{minus}4 at.%). EDS and EFTEM composition profiles show Cr enriched grain boundaries surrounded by regions of Cr depletion.

  1. [Evaluation of prerequisites programs for a HACCP plan for frozen sardine plant].

    Science.gov (United States)

    Rosas, Patricia; Reyes, Genara

    2008-06-01

    Good manufacturing practices (GMP) and sanitation standard operating procedures (SSOP) are prerequisites programs for the application of the Hazard Analysis and Critical Control Point (HACCP) system as a food safety approach during processing. The aim of this study was to evaluate GMP/SSOP prerequisites in processing line of frozen whole sardine (Sardinella aurita). The GMP compliance was verified according to a standard procedure of the Ministry for the Health of Venezuela, and the SSOP were assessed according to a checklist proposed by the FDA. GMP and SSOP were evaluated following a demerit-based approach. A percentage value was calculated and referred to as sanitary effectiveness. Results indicated that the plant had a good level of compliance with GMP from assessment of buildings and facilities, equipment and tools, hygienic requisites of the production, assurance of the hygiene quality, storage and transportation, and the percentage of sanitary effectiveness was 84%. The level of compliance for SSOP was 53,12% with demerits found in all assessed aspects consisting of inexistent guidelines, lack of control in the sanitary plan and lack of leadership in applying corrective actions. Thus, an improvement in the plant sanitation program was designed targeting SSOP.

  2. A method for assessing required course-related skills and prerequisite structure

    Science.gov (United States)

    Johnson, Michael D.; Wang, Jyhwen

    2015-05-01

    Engineering curricula should be dynamic with a goal of constant improvement and refinement. Unfortunately, this is often not the case; courses are developed, altered, and expanded in a piecemeal manner. Namely, as time progresses many programmes end up with courses that are developed and not a developed curriculum. To remedy this shortcoming product, development tools are proposed for the refinement and assessment of an existing curriculum; how these methods could be used for the development of a curriculum is also highlighted. The voice of the customer (VOC) process is used to identify and prioritise desired student skills. The design structure matrix (DSM) is used to assess course prerequisite structure. There is broad agreement between faculty and industry related to which professional skills are the most important. The DSM is shown to be a useful tool in ordering courses and assessing prerequisite structures. The DSM is also shown to be useful in identifying which courses in a curriculum are critical and should be the focus of educational and administrative resources.

  3. Principles, Economic and Institutional Prerequisites for Fiscal Decentralization under Conditions of Post-Conflict Reconstruction

    Directory of Open Access Journals (Sweden)

    Vishnevsky Valentine P.

    2016-11-01

    Full Text Available The aim of the article is to study principles, economic and institutional prerequisites for fiscal decentralization on post-conflict territories. It is determined that fiscal decentralization is one of the main ways to solve problems of post-conflict areas. There justified principles, economic and institutional prerequisites of fiscal decentralization on post-conflict territories with regard to the specificity of individual spheres of fiscal relations. Moreover, different spheres of fiscal relations require different approaches: the sphere of public revenues — providing economic efficiency with the formation of the tax structure contributing to the expansion of the tax base; the sphere of public spending — ensuring social justice and transparency in allocation of social cost at the local level; the sphere of subsidies — narrowing the scope of application of intergovernmental transfers with organizing the redistribution of financial resources under the principle of «center - post-conflict regions - post-conflict recipients»; the sphere of external assistance — ensuring proper coordination for cultivation of new co-operative institutions.

  4. Reasons and Prerequisites of Goodwill Devaluation in the Ukrainian Banking Sector

    Directory of Open Access Journals (Sweden)

    Kundrya-Vysotska Oksana P.

    2014-01-01

    Full Text Available The authors conduct studies of economic prerequisites and factors, which resulted in writing-off significant amounts of goodwill value in Ukrainian banking institutions, which are structural parts of international financial institutions. In the result of analysis of main prerequisites the article identifies external and internal reasons of acknowledgement of devaluation of goodwill in the domestic banking sector. In accordance with the results of the study, the article identifies that acknowledgement of devaluation of goodwill testifies to a negative mood of foreign investors with respect to prospects of business development in the domestic banking market. The article justifies expediency of, separate from goodwill, identification of intangible assets, subject to acknowledgement in the result of unification of banks, in particular the client base of a bank, as an intangible asset with a final date of useful use. It proves that acknowledgement of this asset in the result of unification would allow avoiding significant amounts of write-off of goodwill value under unfavourable economic conditions. The prospect of further studies in this direction is justification of an optimal method of identification of the amount of goodwill devaluation, which would allow avoiding manipulations with financial reporting and would improve quality of presented information about the real financial state of banking institutions.

  5. Responses of mink to auditory stimuli: Prerequisites for applying the ‘cognitive bias’ approach

    DEFF Research Database (Denmark)

    Svendsen, Pernille Maj; Malmkvist, Jens; Halekoh, Ulrich

    2012-01-01

    The aim of the study was to determine and validate prerequisites for applying a cognitive (judgement) bias approach to assessing welfare in farmed mink (Neovison vison). We investigated discrimination ability and associative learning ability using auditory cues. The mink (n = 15 females) were...... mink only showed habituation in experiment 2. Regardless of the frequency used (2 and 18 kHz), cues predicting the danger situation initially elicited slower responses compared to those predicting the safe situation but quickly became faster. Using auditory cues as discrimination stimuli for female...... farmed mink in a judgement bias approach would thus appear to be feasible. However several specific issues are to be considered in order to successfully adapt a cognitive bias approach to mink, and these are discussed....

  6. Paradigm shifts and other prerequisites to facilitate the institutionalising of strategy in South African organisations

    Directory of Open Access Journals (Sweden)

    S. Kruger

    2003-12-01

    Full Text Available South African organisations must undergo a mind shift and adhere to certain prerequisites to survive and be successful. It is evident that companies not changing their mindsets will not survive and be able to create a sustainable competitive advantage and to compete in world markets. Companies have to solve new problems with new paradigms, constantly create something better, something new, create new markets as opposed to increasing market share. The Third Wave development will lead to societal transformation. Moving to Third Wave will imply growth organisations to act like small entrepreneurial businesses that will have the benefit of speed and simplicity but also be able to implement strategy more effectively. Time is of the essence. South African companies have no other option but to move swiftly. The transformation from second to third wave is inevitable.

  7. Controlled assembly: a prerequisite for the use of recombinant spider silk in regenerative medicine?

    Science.gov (United States)

    Rising, Anna

    2014-04-01

    Recent biotechnological progress has enabled the production of spider silk proteins, spidroins, in heterologous hosts. Matrices based on recombinant spidroins support stem cell growth and are well tolerated when implanted in living tissue, thus the material is highly attractive for use in regenerative medicine. However, the matrices made are far from natural silk in terms of mechanical properties and are either spontaneously assembled, which results in heterogeneous products, or spun from harsh solvents with the concomitant risk of harmful remnants in the final products. If we could mimic the spider's aqueous silk spinning process we would likely obtain a material that had reproducible and better characteristics and that more easily could be transferred to clinical practice. Herein, the knowledge of the spiders' silk production system and the prerequisites for artificial spinning and assembly of recombinant proteins are reviewed and discussed in a biomedical context. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  8. ACCURATE KAP METER CALIBRATION AS A PREREQUISITE FOR OPTIMISATION IN PROJECTION RADIOGRAPHY.

    Science.gov (United States)

    Malusek, A; Sandborg, M; Carlsson, G Alm

    2016-06-01

    Modern X-ray units register the air kerma-area product, PKA, with a built-in KAP meter. Some KAP meters show an energy-dependent bias comparable with the maximum uncertainty articulated by the IEC (25 %), adversely affecting dose-optimisation processes. To correct for the bias, a reference KAP meter calibrated at a standards laboratory and two calibration methods described here can be used to achieve an uncertainty of energy-independent dosemeter via a reference beam quality in the clinic, Q1, to beam quality, Q Biases up to 35 % of built-in KAP meter readings were noted. Energy-dependent calibration factors are needed for unbiased PKA Accurate KAP meter calibration as a prerequisite for optimisation in projection radiography.

  9. Web-based diagnosis and therapy of auditory prerequisites for reading and spelling

    Directory of Open Access Journals (Sweden)

    Krammer, Sandra

    2006-11-01

    Full Text Available Cognitive deficits in auditory or visual processing or in verbal short-term-memory are amongst others risk factors for the development of dyslexia (reading and spelling disability. By early identification and intervention (optimally before school entry, detrimental effects of these cognitive deficits on reading and spelling might be prevented. The goal of the CASPAR-project is to develop and evaluate web-based tools for diagnosis and therapy of cognitive prerequisites for reading and spelling, which are appropriate for kindergarten children. In the first approach CASPAR addresses auditory processing disorders. This article describes a computerized and web-based approach for screening and testing phoneme discrimination and for promoting phoneme discrimination abilities through interactive games in kindergarteners.

  10. Active Learning: A Prerequisite for Language Development in the Mixed Ability Class (MAC of Engineering Students

    Directory of Open Access Journals (Sweden)

    Meenakshi Harraw Verma

    2011-07-01

    Full Text Available Engineering students tend to pay more attention to their core subject classes rather than on an English language class. They all come from different social and academic backgrounds and their knowledge of English language varies from one another. A mixed ability group throws many challenges to an English language teacher teaching to a grown up or rather adult group of learners who always pre-define their interests and needs. The primary and the most important challenge in front of the language teacher teaching engineering students is - how to promote active learning in MAC situation? A language teacher to overcome the problems of a mixed ability classroom and promote active learning needs to adopt a number of strategies. The paper studies the MAC situation in an English language classroom of engineering students and makes an attempt to re-define methods for active learning a prerequisite for language development in an engineering classroom.

  11. Organisational and Infrastructure Prerequisites of Creation of an International Logistic Centre

    Directory of Open Access Journals (Sweden)

    Tarnavska Nataliya P.

    2013-11-01

    Full Text Available The goal of the article lies in the study of organisational and infrastructure prerequisites of creation and functioning of integration structures capable, on the basis of logistics, of assisting subjects of economy in structuring and optimisation of material flows and also accompanying financial and information flows. In the result of the study the article identifies irregularities of the transition of national economies to new models of development and prospects of development of logistic provision of the innovation economy connected with them, transformation possibilities and prospects of international integration of the logistic market of Ukraine; it analyses prerequisites and substantiates expediency and shows benefits of formation of an international logistic centre in the city of Ternopil. The mission of the planned international logistic centre is ensuring a qualitatively new level of logistic provision of market participants, which would correspond with the existing world standards. The logistic centre performs realisation of its tasks and conduct of functions in the process of interaction with partners – participants of the logistic chain. The logistic centre should become an operator of flows of transit and export-import cargoes and it would perform important logistic functions connected not only with organisation of shipping operations but also with sorting, storing, packing and some other functions at the level of the best world representatives of the logistic servicing. In order to ensure successful activity of such a centre, it is required to adapt tariff policy of the state to international standards, to expand a list of relevant services, to reduce terms of cargo handling and to introduce modern technologies of information processing intensively.

  12. Magnetic Properties of Epitaxial Cr/Cr2O3/ Cr Multilayers

    Science.gov (United States)

    Mukherjee, Tathagata; Sahoo, Sarbeswar; Binek, Christian

    2007-03-01

    We study Cr/Cr2O3/Cr trilayer structures grown by Molecular Beam Epitaxy on (111) oriented Al2O3 substrates. X-ray diffraction reveals perfect single crystalline (110) Cr and stoichiometric single crystalline Cr2O3 (111) films. Both, Cr and Cr2O3 order antiferromagnetically with bulk N'eel temperatures of 311 and 307K, respectively. Cr is an itinerant antiferromagnet where the antiferromagnetic (AF) order establishes as an incommensurate spin density wave. Cr2O3 in contrast is an AF insulator with localized magnetic moments where magnetoelectric and piezomagnetic effects are both symmetry allowed. Its insulating, magnetoelectric and piezoelectric properties make Cr2O3 an interesting material for extrinsically controlled tunnel barriers in TMR type structures. The lattice mismatch of ˜1.2% at the Cr -- Cr2O3 interface creates a strong stress induced piezomagnetic moment revealed by SQUID measurements. The interaction between the piezomoment and the spin distribution at the Cr- interface gives rise to a rich scenario of magnetic proximity effects which we study by SQUID magnetometry, magneto-optical Kerr effect and electrical transport measurements.

  13. Determination of prerequisites for implementation of IPOs in the Czech capital market

    Directory of Open Access Journals (Sweden)

    Tomáš Meluzín

    2008-01-01

    Full Text Available In advanced markets, IPOs represent an opportunity to obtain the necessary capital for further company development. This form of financing is significant not only for the joint-stock company itself, for which an IPO is an alternative to debt financing, but also for further development of the capital market as a whole. That is to say, one of the fundamental functions of the capital market, the allocation function, is accomplished by means of IPOs. It follows from investigations of the situation in IPOs in the Czech Republic that financing company development through IPOs, which are linked with entrance into the capital market, has not become common practice in the Czech capital market. Comparing the present situation with the situation in international markets, it must be stated that the Czech capital market shows anomalies not only with regard to advanced capital markets such as those in the USA or Japan but also in reference to markets in Central and Eastern Europe. In the past, unfavourable conditions resulting from legislation and the institutional environment were considered the major cause of the long-term low numbers of initial public offerings in the Czech Republic. It follows from the results of the analysis of legislative barriers to carrying out IPOs that in recent years, a number of steps were taken to draw the Czech capital market nearer to the European standard, at least formally. Laws were passed that determine the scope and regulations for entrepreneurial activities of individual subjects, and an independent authority was set up that kept an eye on the tran­spa­ren­cy of the market and compliance with the given regulations; there are institutional and technical prerequisites available that facilitate trade in securities. Nowadays there are no more any legislative or general economic barriers, designated as significant obstacles for IPO realization in the Czech environment in the past. It depends mainly on approach of individual

  14. CR reliability testing

    Science.gov (United States)

    Honeyman-Buck, Janice C.; Rill, Lynn; Frost, Meryll M.; Staab, Edward V.

    1998-07-01

    The purpose of this work was to develop a method for systematically testing the reliability of a CR system under realistic daily loads in a non-clinical environment prior to its clinical adoption. Once digital imaging replaces film, it will be very difficult to revert back should the digital system become unreliable. Prior to the beginning of the test, a formal evaluation was performed to set the benchmarks for performance and functionality. A formal protocol was established that included all the 62 imaging plates in the inventory for each 24-hour period in the study. Imaging plates were exposed using different combinations of collimation, orientation, and SID. Anthropomorphic phantoms were used to acquire images of different sizes. Each combination was chosen randomly to simulate the differences that could occur in clinical practice. The tests were performed over a wide range of times with batches of plates processed to simulate the temporal constraints required by the nature of portable radiographs taken in the Intensive Care Unit (ICU). Current patient demographics were used for the test studies so automatic routing algorithms could be tested. During the test, only three minor reliability problems occurred, two of which were not directly related to the CR unit. One plate was discovered to cause a segmentation error that essentially reduced the image to only black and white with no gray levels. This plate was removed from the inventory to be replaced. Another problem was a PACS routing problem that occurred when the DICOM server with which the CR was communicating had a problem with disk space. The final problem was a network printing failure to the laser cameras. Although the units passed the reliability test, problems with interfacing to workstations were discovered. The two issues that were identified were the interpretation of what constitutes a study for CR and the construction of the look-up table for a proper gray scale display.

  15. A prerequisite for the effective transfer of the shape-memory effect to cotton fibers

    Science.gov (United States)

    Liem, H.; Yeung, L. Y.; Hu, J. L.

    2007-06-01

    Subtle interaction between shape-memory polymer and cellulose fibers within fabrics remains a critical issue for understanding their thermal-mechanical properties and thus the shape-memory behavior in cotton fibers. We demonstrate here the efficacy of Raman spectroscopy to probe the induced stresses in warp and weft fibers, presenting physicochemical features for cellulose fibers finished with macromolecule polyurethane and small-molecule dimethyloldihydroxyethyleneurea. Accordingly, a possible mechanism for transfer of the shape-memory effect to fabrics is proposed. Forming as a coating on the fiber surface after the finishing process, the shape-memory polymer takes a critical role in reducing the residual stress in weft fibers, establishing the prerequisite for reserving the shape-memory effect to fabric. In addition, this work has demonstrated that Raman spectroscopy is able to probe the residual stresses in cotton fabrics after being treated by chemicals in addition to that due to physical deformation. Our result provides clear evidence that in the finishing process strength reduction in fibers in general is not only caused solely by a chemical reaction, but also by a physical modification of the cotton structure.

  16. β-Catenin inactivation is a pre-requisite for chick retina regeneration.

    Directory of Open Access Journals (Sweden)

    Jie Zhu

    Full Text Available In the present study we explored the role of β-catenin in mediating chick retina regeneration. The chick can regenerate its retina by activating stem/progenitor cells present in the ciliary margin (CM of the eye or via transdifferentiation of the retinal pigmented epithelium (RPE. Both modes require fibroblast growth factor 2 (FGF2. We observed, by immunohistochemistry, dynamic changes of nuclear β-catenin in the CM and RPE after injury (retinectomy. β-Catenin nuclear accumulation was transiently lost in cells of the CM in response to injury alone, while the loss of nuclear β-catenin was maintained as long as FGF2 was present. However, nuclear β-catenin positive cells remained in the RPE in response to injury and were BrdU-/p27+, suggesting that nuclear β-catenin prevents those cells from entering the cell cycle. If FGF2 is present, the RPE undergoes dedifferentiation and proliferation concomitant with loss of nuclear β-catenin. Moreover, retinectomy followed by disruption of active β-catenin by using a signaling inhibitor (XAV939 or over-expressing a dominant negative form of Lef-1 induces regeneration from both the CM and RPE in the absence of FGF2. Our results imply that β-catenin protects cells of the CM and RPE from entering the cell cycle in the developing eye, and specifically for the RPE during injury. Thus inactivation of β-catenin is a pre-requisite for chick retina regeneration.

  17. [Medical, educational and neurophysiological prerequisites to the formation of the motivation to exercises in students].

    Science.gov (United States)

    Khramtsov, P I; Sedova, A S; Berezina, N O; Viatleva, O A

    2015-01-01

    A characteristic feature of the life activity of modern children and adolescents is the couch potato, mostly "sedentary" lifestyle. Biomedical and psychosocial significance of motor activity (MA) stipulates the necessity of the substantiation of scientific and methodological approaches to the formation of the motivation to exercises and sports in children. The purpose of the study was in the scientific substantiation and the delivery of medical, pedagogical and neurophysiological prerequisites for the formation of the motivation to increase MA in students in current conditions of their life activity. There were examined 189 students from 2-5th and 9th classes, out of them 65 students were observed in the dynamics of the school year; 585 students from the 1st-11th classes participated in the survey. Results of the study allowed to reveal the relation of students to the lessons of physical training, to evaluate the impact of a new educational program on the functional possibilities of the body of children from the special medical group "A" and to reveal the neurophysiological features of adolescents with different needs in motion.

  18. Understanding entangled cerebral networks: A prerequisite for restoring brain function with brain-computer interfaces

    Directory of Open Access Journals (Sweden)

    Emmanuel eMandonnet

    2014-05-01

    Full Text Available Historically, cerebral processing has been conceptualized as a framework based on statically localized functions. However, a growing amount of evidence supports a hodotopical (delocalized and flexible organization. A number of studies have reported absence of a permanent neurological deficit after massive surgical resections of eloquent brain tissue. These results highlight the tremendous plastic potential of the brain. Understanding anatomo-functional correlates underlying this cerebral reorganization is a prerequisite to restore brain functions through brain-computer interfaces (BCIs in patients with cerebral diseases, or even to potentiate brain functions in healthy individuals. Here, we review current knowledge of neural networks that could be utilized in the BCIs that enable movements and language. To this end, intraoperative electrical stimulation in awake patients provides valuable information on the cerebral functional maps, their connectomics and plasticity. Overall, these studies indicate that the complex cerebral circuitry that underpins interactions between action, cognition and behavior should be throughly investigated before progress in BCI approaches can be achieved.

  19. Neuroinflammation is not a prerequisite for diabetes-induced tau phosphorylation

    Directory of Open Access Journals (Sweden)

    Judith M Van Der Harg

    2015-11-01

    Full Text Available Abnormal phosphorylation and aggregation of tau is a key hallmark of Alzheimer's disease (AD. AD is a multifactorial neurodegenerative disorder for which Diabetes Mellitus (DM is a risk factor. In animal models for DM, the phosphorylation and aggregation of tau is induced or exacerbated, however the underlying mechanism is unknown. In addition to the metabolic dysfunction, DM is characterized by chronic low-grade inflammation. This was reported to be associated with a neuroinflammatory response in the hypothalamus of DM animal models. Neuroinflammation is also implicated in the development and progression of AD. It is unknown whether DM also induces neuroinflammation in brain areas affected in AD, the cortex and hippocampus. Here we investigated whether neuroinflammation could be the mechanistic trigger to induce tau phosphorylation in the brain of DM animals. Two distinct diabetic animal models were used; rats on free-choice high-fat high-sugar (fcHFHS diet that are insulin resistant and streptozotocin-treated rats that are insulin deficient. The streptozotocin-treated animals demonstrated increased tau phosphorylation in the brain as expected, whereas the fcHFHS diet fed animals did not. Remarkably, neither of the diabetic animal models showed reactive microglia or increased GFAP and COX-2 levels in the cortex or hippocampus. From this, we conclude: 1. DM does not induce neuroinflammation in brain regions affected in AD, and 2. Neuroinflammation is not a prerequisite for tau phosphorylation. Neuroinflammation is therefore not the mechanism that explains the close connection between DM and AD.

  20. Trisomy 21- affected placentas highlight prerequisite factors for human trophoblast fusion and differentiation.

    Science.gov (United States)

    Malassiné, André; Frendo, Jean-Louis; Evain-Brion, Danièle

    2010-01-01

    Trophoblastic cell fusion is one essential step of the human trophoblast differentiation pathway and is a multifactorial and dynamic process finely regulated and still poorly known. Disturbances of syncytiotrophoblast formation are observed in numerous pathological clinical conditions such as preeclampsia, intrauterine growth retardation and trisomy 21. In this review, we summarize current knowledge of the different membrane proteins directly involved in trophoblastic cell fusion, which we identified by using the physiological model of primary culture of villous trophoblastic cells. Connexin 43 and gap junctional intercellular communication point to the role of molecular exchanges through connexin channels preceding membrane fusion. Zona occludens-1, which can interact with connexin 43, is also directly involved in trophoblast fusion. The recently identified fusogenic membrane retroviral envelop glycoproteins syncytin 1 (encoded by the HERV-W gene) and syncytin 2 (encoded by the FRD gene) and their receptors are major factors involved in human placental development . We describe the increasing number of factors promoting or inhibiting trophoblast fusion and differentiation and emphasize the role of human chorionic gonadotropin (hCG) and its receptor. Indeed, in trisomy 21 the dynamic process leading to membrane fusion is impaired due to an abnormal hCG signaling. This abnormal trophoblast fusion and differentiation in trisomy 21-affected placenta is reversible in vitro. Trisomy 21 trophoblastic cell culture may therefore be useful to identify the possible large number of prerequisite factors involved in trophoblast fusion, the limiting step of trophoblast differentiation.

  1. Are left fronto-temporal brain areas a prerequisite for normal music-syntactic processing?

    Science.gov (United States)

    Sammler, Daniela; Koelsch, Stefan; Friederici, Angela D

    2011-06-01

    An increasing number of neuroimaging studies in music cognition research suggest that "language areas" are involved in the processing of musical syntax, but none of these studies clarified whether these areas are a prerequisite for normal syntax processing in music. The present electrophysiological experiment tested whether patients with lesions in Broca's area (N=6) or in the left anterior temporal lobe (N=7) exhibit deficits in the processing of structure in music compared to matched healthy controls (N=13). A chord sequence paradigm was applied, and the amplitude and scalp topography of the Early Right Anterior Negativity (ERAN) was examined, an electrophysiological marker of musical syntax processing that correlates with activity in Broca's area and its right hemisphere homotope. Left inferior frontal gyrus (IFG) (but not anterior superior temporal gyrus - aSTG) patients with lesions older than 4 years showed an ERAN with abnormal scalp distribution, and subtle behavioural deficits in detecting music-syntactic irregularities. In one IFG patient tested 7 months post-stroke, the ERAN was extinguished and the behavioural performance remained at chance level. These combined results suggest that the left IFG, known to be crucial for syntax processing in language, plays also a functional role in the processing of musical syntax. Hence, the present findings are consistent with the notion that Broca's area supports the processing of syntax in a rather domain-general way.

  2. Identifying photoreceptors in blind eyes caused by RPE65 mutations: Prerequisite for human gene therapy success.

    Science.gov (United States)

    Jacobson, Samuel G; Aleman, Tomas S; Cideciyan, Artur V; Sumaroka, Alexander; Schwartz, Sharon B; Windsor, Elizabeth A M; Traboulsi, Elias I; Heon, Elise; Pittler, Steven J; Milam, Ann H; Maguire, Albert M; Palczewski, Krzysztof; Stone, Edwin M; Bennett, Jean

    2005-04-26

    Mutations in RPE65, a gene essential to normal operation of the visual (retinoid) cycle, cause the childhood blindness known as Leber congenital amaurosis (LCA). Retinal gene therapy restores vision to blind canine and murine models of LCA. Gene therapy in blind humans with LCA from RPE65 mutations may also have potential for success but only if the retinal photoreceptor layer is intact, as in the early-disease stage-treated animals. Here, we use high-resolution in vivo microscopy to quantify photoreceptor layer thickness in the human disease to define the relationship of retinal structure to vision and determine the potential for gene therapy success. The normally cone photoreceptor-rich central retina and rod-rich regions were studied. Despite severely reduced cone vision, many RPE65-mutant retinas had near-normal central microstructure. Absent rod vision was associated with a detectable but thinned photoreceptor layer. We asked whether abnormally thinned RPE65-mutant retina with photoreceptor loss would respond to treatment. Gene therapy in Rpe65(-/-) mice at advanced-disease stages, a more faithful mimic of the humans we studied, showed success but only in animals with better-preserved photoreceptor structure. The results indicate that identifying and then targeting retinal locations with retained photoreceptors will be a prerequisite for successful gene therapy in humans with RPE65 mutations and in other retinal degenerative disorders now moving from proof-of-concept studies toward clinical trials.

  3. Positive Prerequisites for the Use of Reliefs in the Payment of Dues on Social Insurance Contributions

    Directory of Open Access Journals (Sweden)

    Zbigniew Ofiarski

    2014-06-01

    Full Text Available It is permissible to use reliefs in the payment of social security contributions, based either on a definitive waiver by the creditor of the whole or relevant part of the amount due (partial or complete remission or only a temporary waiver of such amounts (payment deferral or payment in installments. The use of such reliefs is possible upon the occurrence of conditions laid down in the Act, for example, in the case of total non-recovery of contributions, for economic or other reasons worth considering, if justified by important interests of the person concerned. The prerequisites mentioned above have a nature of general clauses, allowing for their flexible adjustment to specific situations. Entities authorized to grant reliefs in the payment of social security contributions act within the limits of administrative discretion. But it is not a fully free operation, because the economic impact resulting from the use of such reliefs has a direct impact on the financial balance of earmarked funds which finance social security benefits, in particular pensions, disability allowances and other benefits.

  4. Comparative Analysis on Romanian Taxation in the European Context, as a Prerequisite for Tax Harmonization

    Directory of Open Access Journals (Sweden)

    Georgeta Dragomir

    2011-08-01

    Full Text Available The issue of tax harmonization at EU level is becoming more present in the global crisis context, as it is both accepted and disputed by the European officials that manifest their preference for either coordination or tax competition. The crisis has generated, among other things, large budget deficits and a dangerous crisis of debts in the euro area, a situation that has attracted many followers in terms of tax harmonization. There is a European regulated Area, a unique European market, European unique currency and common monetary policy which regard the criteria relating to public finances (budget deficits, public debt. We ask ourselves to what extent it is necessary to achieve coordination or even tax unification and how does that help. This paper examines, according to the statistical database, the level and type of taxation, on categories of taxes and as a share of GDP, in Romania compared to EU countries, in order to clarify the current situation, the existing differences, the prospect of good European practice. If we speak of tax harmonization in terms of being acquired by Romania, the conclusion is that we can not report only to the technical or quantifiable aspects, as compared with the best results in European area, because they do not represent a guarantee of similar results. The fiscal policy must be both a prerequisite and a consequence of sustainable economic and financial policies, and the tax harmonization can only help insofar as it relates to the relationships between states and not at the tax level.

  5. THE ECONOMIC AND SOCIAL COORDINATES OF DEVELOPING A SPORT ENTREPRENEURSHIP INDEX – CURRENT CHALLENGES AND PREREQUISITES

    Directory of Open Access Journals (Sweden)

    MUNTEANU SEBASTIAN MADALIN

    2015-07-01

    Full Text Available Focussing on the consideration of the multivariate relationship between sport and economics, the present study is based on the sport potential of supporting economic growth through the enhancement of the relatively new domain of “sport entrepreneurship”. The brief revision of the specialized literature regarding the development of sport entrepreneurship in general terms is followed by a series of fundamental factors for the innovative proposal of a sport entrepreneurship index (SEI in the European Union member countries. The methodological issues concerning the structure of the index represent the main novelty aspect of this research, which aims to be a prerequisite of a future thorough analysis regarding the micro- and macro-economic implications of developing a sport entrepreneurship index (SEI in EU countries. The main identified challenge is a scientific one and it resides in the summative assessment of the elements representing entrepreneurship, sport and culture in the SEI, whereas the necessity of determining such an index appears because of economic and social reasons.

  6. Prerequisites for modeling price and return data series for the Bucharest Stock Exchange

    Directory of Open Access Journals (Sweden)

    Andrei TINCA

    2013-11-01

    Full Text Available Time series data from the capital market exhibits certain qualities which invalidate the hypotheses necessary for obtaining meaningful results from statistical modeling. This paper presents some of these qualities by looking at the time series for prices and returns on the Romanian Stock Exchange. The examples are based on the price time series and return time series of the Antibiotice securities and the BET-C index. The choice of a certain security and of the stock exchange index has been made with the intention of analyzing, in the future, the correlation between these two variables, and drawing significant conclusions which can be used for forecasts.Firstly, we will identify the empirical proprieties of the capital market, as they are described in the field research. Secondly, we will investigate the prerequisites for modeling chronological data series; these are stationary mean and variance. In the paper, the three methods are used: graphical representation, autocorrelation and the ADF test (Augmented Dickey-Fuller. For the frequent cases where the mean is not stationary, we will present the time series differentiation method, which can be used to obtain stationary values.Lastly, we will investigate the normality of the time series through the skewness and kurtosis methods, and through the Jarque-Bera statistic. We find out a characteristic for the capital market, in that the majority of the time series for securities have non-normal distributions.

  7. The Impact of Prerequisite General Education Courses on the ETS Major Field Test for Business (MFT-B)

    Science.gov (United States)

    Ritchie, Charles Michael; Rodriguez, Linda Carol; Harrison, David S.; Wates, Kathleen W.

    2014-01-01

    The authors explore the relationship between general education prerequisite courses, used for schools of business admission, and predicted grade point averages (PGPAs) with the Major Field Test in Business (MFT-B). The MFT-B is designed to assess the general business knowledge of students at the end of their programs. There is no known literature…

  8. Democratization of Education as Prerequisite for Social Economic and Cultural Progress in a Multi-Cultural Society

    Science.gov (United States)

    Madumere, S. C.; Olisaemeka, B. U.

    2011-01-01

    This paper focuses on democratization of education as a prerequisite for social, economic and cultural progress in a multi-cultural society, such as Nigeria. Attempt was made to define and explain the major concepts in the paper. Education was explained as an instrument of democracy and as function of socialization, culture and economic…

  9. Student- and faculty-reported importance of science prerequisites for osteopathic medical school: a survey-based study.

    Science.gov (United States)

    Binstock, Judith; Junsanto-Bahri, Tipsuda

    2014-04-01

    The relevance of current standard medical school science prerequisites is being reexamined. (1) To identify which science prerequisites are perceived to best prepare osteopathic medical students for their basic science and osteopathic manipulative medicine (OMM) coursework and (2) to determine whether science prerequisites for osteopathic medical school should be modified. Preclinical osteopathic medical students and their basic science and OMM faculty from 3 colleges of osteopathic medicine were surveyed about the importance of specific science concepts, laboratories, and research techniques to medical school coursework. Participants chose responses on a 5-point scale, with 1 indicating "strongly disagree" or "not important" and 5 indicating "strongly agree" or "extremely important." Participants were also surveryed on possible prerequisite modifications. Student responses (N=264) to the general statement regarding prerequisites were "neutral" for basic science coursework and "disagree" for OMM coursework, with mean (standard deviation [SD]) scores of 3.37 (1.1) and 2.68 (1.2), respectively. Faculty responses (N=49) were similar, with mean (SD) scores of 3.18 (1.1) for basic science coursework and 2.67 (1.2) for OMM coursework. Student mean (SD) scores were highest for general biology for basic science coursework (3.93 [1.1]) and physics for OMM coursework (2.5 [1.1]). Student mean (SD) scores were lowest for physics for basic science coursework (1.79 [1.2]) and organic chemistry for OMM coursework (1.2 [0.7]). Both basic science and OMM faculty rated general biology highest in importance (mean [SD] scores, 3.73 [0.9] and 4.22 [1.0], respectively). Students and faculty rated biochemistry high in importance for basic science coursework (mean [SD] scores of 3.66 [1.2] and 3.32 [1.2], respectively). For basic science coursework, students and faculty rated most laboratories as "important," with the highest mean (SD) ratings for general anatomy (students, 3.66 [1

  10. Establishment of technical prerequisites for cell irradiation experiments with laser-accelerated electrons.

    Science.gov (United States)

    Beyreuther, E; Enghardt, W; Kaluza, M; Karsch, L; Laschinsky, L; Lessmann, E; Nicolai, M; Pawelke, J; Richter, C; Sauerbrey, R; Schlenvoigt, H P; Baumann, M

    2010-04-01

    In recent years, laser-based acceleration of charged particles has rapidly progressed and medical applications, e.g., in radiotherapy, might become feasible in the coming decade. Requirements are monoenergetic particle beams with long-term stable and reproducible properties as well as sufficient particle intensities and a controlled delivery of prescribed doses at the treatment site. Although conventional and laser-based particle accelerators will administer the same dose to the patient, their different time structures could result in different radiobiological properties. Therefore, the biological response to the ultrashort pulse durations and the resulting high peak dose rates of these particle beams have to be investigated. The technical prerequisites, i.e., a suitable cell irradiation setup and the precise dosimetric characterization of a laser-based particle accelerator, have to be realized in order to prepare systematic cell irradiation experiments. The Jena titanium:sapphire laser system (JETI) was customized in preparation for cell irradiation experiments with laser-accelerated electrons. The delivered electron beam was optimized with regard to its spectrum, diameter, dose rate, and dose homogeneity. A custom-designed beam and dose monitoring system, consisting of a Roos ionization chamber, a Faraday cup, and EBT-1 dosimetry films, enables real-time monitoring of irradiation experiments and precise determination of the dose delivered to the cells. Finally, as proof-of-principle experiment cell samples were irradiated using this setup. Laser-accelerated electron beams, appropriate for in vitro radiobiological experiments, were generated with a laser shot frequency of 2.5 Hz and a pulse length of 80 fs. After laser acceleration in the helium gas jet, the electrons were filtered by a magnet, released from the vacuum target chamber, and propagated in air for a distance of 220 mm. Within this distance a lead collimator (aperture of 35 mm) was introduced, leading

  11. Intravirion cohesion of matrix protein M1 with ribonucleocapsid is a prerequisite of influenza virus infectivity.

    Science.gov (United States)

    Zhirnov, O P; Manykin, A A; Rossman, J S; Klenk, H D

    2016-05-01

    Influenza virus has two major structural modules, an external lipid envelope and an internal ribonucleocapsid containing the genomic RNA in the form of the ribonucleoprotein (RNP) complex, both of which are interlinked by the matrix protein M1. Here we studied M1-RNP cohesion within virus exposed to acidic pH in vitro. The effect of acidification was dependent on the cleavage of the surface glycoprotein HA. Acidic pH caused a loss of intravirion RNP-M1 cohesion and activated RNP polymerase activity in virus with cleaved HA (HA1/2) but not in the uncleaved (HA0) virus. The in vitro acidified HA1/2 virus rapidly lost infectivity whereas the HA0 one retained infectivity, following activation by trypsin, suggesting that premature activation and release of the RNP is detrimental to viral infectivity. Rimantadine, an inhibitor of the M2 ion channel, was found to protect the HA1/2 virus interior against acidic disintegration, confirming that M2-dependent proton translocation is essential for the intravirion RNP release and suggesting that the M2 ion channel is only active in virions with cleaved HA. Acidic treatment of both HA0 and HA1/2 influenza viruses induces formation of spikeless bleb-like protrusion of ~ 25 nm in diameter on the surface of the virion, though only the HA1/2 virus was permeable to protons and permitted RNP release. It is likely that this bleb corresponds to the M2-enriched and M1-depleted focus arising from pinching off of the virus during the completion of budding. Cooperatively, the data suggest that the influenza virus has an asymmetric structure where the M1-mediated organization of the RNP inside the virion is a prerequisite for infectious entry into target cell. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Prerequisites to launch neuroprotective trials in Parkinson's disease: an industry perspective.

    Science.gov (United States)

    Streffer, Johannes R; Grachev, Igor D; Fitzer-Attas, Cheryl; Gomez-Mancilla, Baltazar; Boroojerdi, Babak; Bronzova, Juliana; Ostrowitzki, Susanne; Victor, Stephen J; Fontoura, Paulo; Alexander, Robert

    2012-04-15

    Realizing that 60% to 80% of dopaminergic nigrostriatal neurons are nonfunctional at the time of clinical diagnosis, there is an emerging consensus that disease-modifying treatments should be initiated in the earliest stages of Parkinson's disease (PD). To date, clinical trial designs and metrics in PD have been focused on motor symptoms as the core feature of the clinical disease. To identify earlier or "pre-motor" populations in PD, new markers have been proposed. We address the prerequisites needed to use these pre-motor markers in clinical trials for the selection of subjects, definition of populations, and monitoring of disease progression. This may require the development of new diagnostic criteria potentially based on non-motor clinical signs, imaging techniques, or biological features, all requiring discussion in a regulatory framework. Questions addressed include: Which steps must be taken to gain a broad consensus in the field from academic opinion leaders, patient advocacy groups, regulatory bodies, and industry? How do we prevent the selection of subgroups, which may not be representative of the full disease spectrum? Is there a way forward in personalized medicine? How do we balance risk and benefit in an at-risk population? While many tools are available, a concerted effort is required to develop integrated data sets, as well as to achieve the necessary standardization for multicenter clinical trials. To this end, public-private consortia (including academic centers, patient advocacy groups, and industry) will be of crucial importance to prospectively investigate and define the best tools and treatment paradigms.

  13. Loss of PSD-95 enrichment is not a prerequisite for spine retraction.

    Science.gov (United States)

    Woods, Georgia F; Oh, Won Chan; Boudewyn, Lauren C; Mikula, Sarah K; Zito, Karen

    2011-08-24

    Changes in neuronal structure are thought to underlie long-term behavioral modifications associated with learning and memory. In particular, considerable evidence implicates the destabilization and retraction of dendritic spines along with the loss of spine synapses as an important cellular mechanism for refining brain circuits, yet the molecular mechanisms regulating spine elimination remain ill-defined. The postsynaptic density protein, PSD-95, is highly enriched in dendritic spines and has been associated with spine stability. Because spines with low levels of PSD-95 are more dynamic, and the recruitment of PSD-95 to nascent spines has been associated with spine stabilization, we hypothesized that loss of PSD-95 enrichment would be a prerequisite for spine retraction. To test this hypothesis, we used dual-color time-lapse two-photon microscopy to monitor rat hippocampal pyramidal neurons cotransfected with PSD-95-GFP and DsRed-Express, and we analyzed the relationship between PSD-95-GFP enrichment and spine morphological changes. Consistent with our hypothesis, we found that the majority of spines that retracted were relatively unenriched for PSD-95-GFP. However, in the subset of PSD-95-GFP-enriched spines that retracted, spine shrinkage and loss of PSD-95-GFP were tightly coupled, suggesting that loss of PSD-95-GFP enrichment did not precede spine retraction. Moreover, we found that, in some instances, spine retraction resulted in a significant enrichment of PSD-95-GFP on the dendritic shaft. Our data support a model of spine retraction in which loss of PSD-95 enrichment is not required prior to the destabilization of spines.

  14. Prerequisites for understanding climate-change impacts on northern prairie wetlands

    Science.gov (United States)

    Anteau, Michael J.; Wiltermuth, Mark T.; Post van der Burg, Max; Pearse, Aaron T.

    2016-01-01

    The Prairie Pothole Region (PPR) contains ecosystems that are typified by an extensive matrix of grasslands and depressional wetlands, which provide numerous ecosystem services. Over the past 150 years the PPR has experienced numerous landscape modifications resulting in agricultural conversion of 75–99 % of native prairie uplands and drainage of 50–90 % of wetlands. There is concern over how and where conservation dollars should be spent within the PPR to protect and restore wetland basins to support waterbird populations that will be robust to a changing climate. However, while hydrological impacts of landscape modifications appear substantial, they are still poorly understood. Previous modeling efforts addressing impacts of climate change on PPR wetlands have yet to fully incorporate interacting or potentially overshadowing impacts of landscape modification. We outlined several information needs for building more informative models to predict climate change effects on PPR wetlands. We reviewed how landscape modification influences wetland hydrology and present a conceptual model to describe how modified wetlands might respond to climate variability. We note that current climate projections do not incorporate cyclical variability in climate between wet and dry periods even though such dynamics have shaped the hydrology and ecology of PPR wetlands. We conclude that there are at least three prerequisite steps to making meaningful predictions about effects of climate change on PPR wetlands. Those evident to us are: 1) an understanding of how physical and watershed characteristics of wetland basins of similar hydroperiods vary across temperature and moisture gradients; 2) a mechanistic understanding of how wetlands respond to climate across a gradient of anthropogenic modifications; and 3) improved climate projections for the PPR that can meaningfully represent potential changes in climate variability including intensity and duration of wet and dry periods. Once

  15. Can Total Quality Management Succeed at Your College--Now? (Does Your College Meet the Essential Prerequisites and Underlying Assumptions of TQM?)

    Science.gov (United States)

    Hammons, James O.

    1994-01-01

    Defines Total Quality Management (TQM) and describes prerequisites for successful implementation, underlying assumptions, and the cultural barriers hindering implementation. Indicates that TQM's long-term benefits outweigh costs at most colleges. Urges practitioners to rate their schools with respect to the prerequisites and assumptions to…

  16. Can Total Quality Management Succeed at Your College--Now? (Does Your College Meet the Essential Prerequisites and Underlying Assumptions of TQM?)

    Science.gov (United States)

    Hammons, James O.

    1994-01-01

    Defines Total Quality Management (TQM) and describes prerequisites for successful implementation, underlying assumptions, and the cultural barriers hindering implementation. Indicates that TQM's long-term benefits outweigh costs at most colleges. Urges practitioners to rate their schools with respect to the prerequisites and assumptions to…

  17. Electrochemical Characterization of Multilayer Cr/CrN-Based Coatings

    Directory of Open Access Journals (Sweden)

    Fabio C. Caiazzo

    2014-07-01

    Full Text Available In this work, a series of mono-and multilayer coatings were considered. They consisted of CrN and Cr prepared by physical vapor deposition with a cathodic arc. The most common steels for molds of plastics were chosen as substrates: X37CrMoV5-1 (SMV3, X2NiCoMo18-8-5 (MARVAL M1, X105CrCoMo18-2 (N690 and X40CrMo15 (X13T6. The samples were made with surface state conditions reproducing the main finishes required for molding of plastics: mirror, electro-eroded, sandblasted and ground finish. The coatings were characterized morphologically and chemically. The corrosion behavior of bare and coated steels was evaluated by electrochemical methods.

  18. Persistent Identifiers: a Prerequisite to Establish the Framework for Scholarly Link Exchange—Scholix

    Science.gov (United States)

    Stocker, M.; Mokrane, M.; Burton, A.; Koers, H.

    2016-12-01

    The Scholix framework—Scholarly Link Exchange—is a set of aspirational principles and practical guidelines developed under the umbrella of a joint Working Group of the Research Data Alliance (RDA) and the World Data System (WDS). It supports a global open information ecosystem unveiling the links between scholarly literature and underpinning research data. The core objectives of the framework are to (1) increase visibility and discoverability of data and articles, (2) place data in context to enable re-use, and (3) support credit attribution mechanisms. Thus, facilitating reproducibility and the transparent evaluation of science. Scholix provides an evolving lightweight set of Guidelines to increase interoperability rather than a normative standard. It consists initially of a conceptual and information models, information standards and encoding guidelines, and options for encoding and exchange protocols. An essential prerequisite to enable the proposed framework is the use of global, unique and persistent identifiers for research objects (such as data and literature). Scholix provides incentives and encourages best practice in the use of such identifiers and standardised referencing. The Data and Literature Interlinking Service (DLI: dliservice.research-infrastructures.eu) is the first exemplar of an aggregation and query service supported by the Scholix framework which will allow the emergence of third party services such as domain-specific aggregations, integrations with other global services, discovery tools, impact assessments, etc. Scholix is already implemented by existing hubs or global aggregators of data-literature link information such as DataCite, CrossRef, OpenAIRE, and EMBL-EBI building on the capacities of existing Persistent Identifier Systems (PIDs) such as Digital Object Identifiers (DOI) and Accession Numbers. These hubs in turn work with their natural communities of data centres or literature publishers to collect the information through

  19. Intravirion cohesion of matrix protein M1 with ribonucleocapsid is a prerequisite of influenza virus infectivity

    Energy Technology Data Exchange (ETDEWEB)

    Zhirnov, O.P., E-mail: zhirnov@inbox.ru [D.I. Ivanovsky Institute of Virology, Moscow 123098 (Russian Federation); Manykin, A.A. [D.I. Ivanovsky Institute of Virology, Moscow 123098 (Russian Federation); Rossman, J.S. [School of Biosciences, University of Kent, Canterbury CT27NJ (United Kingdom); Klenk, H.D. [Institute of Virology, Philipps University, Marburg 35037 (Germany)

    2016-05-15

    Influenza virus has two major structural modules, an external lipid envelope and an internal ribonucleocapsid containing the genomic RNA in the form of the ribonucleoprotein (RNP) complex, both of which are interlinked by the matrix protein M1. Here we studied M1-RNP cohesion within virus exposed to acidic pH in vitro. The effect of acidification was dependent on the cleavage of the surface glycoprotein HA. Acidic pH caused a loss of intravirion RNP-M1 cohesion and activated RNP polymerase activity in virus with cleaved HA (HA1/2) but not in the uncleaved (HA0) virus. The in vitro acidified HA1/2 virus rapidly lost infectivity whereas the HA0 one retained infectivity, following activation by trypsin, suggesting that premature activation and release of the RNP is detrimental to viral infectivity. Rimantadine, an inhibitor of the M2 ion channel, was found to protect the HA1/2 virus interior against acidic disintegration, confirming that M2-dependent proton translocation is essential for the intravirion RNP release and suggesting that the M2 ion channel is only active in virions with cleaved HA. Acidic treatment of both HA0 and HA1/2 influenza viruses induces formation of spikeless bleb-like protrusion of ~25 nm in diameter on the surface of the virion, though only the HA1/2 virus was permeable to protons and permitted RNP release. It is likely that this bleb corresponds to the M2-enriched and M1-depleted focus arising from pinching off of the virus during the completion of budding. Cooperatively, the data suggest that the influenza virus has an asymmetric structure where the M1-mediated organization of the RNP inside the virion is a prerequisite for infectious entry into target cell. - Highlights: • The influenza A virus has a novel asymmetric internal structure. • The structure is largely maintained by M1-RNP cohesion within the virion. • This asymmetry plays an important role during viral entry, facilitating virus uncoating and the initiation of a productive

  20. Digital Model-Based Engineering: Expectations, Prerequisites, and Challenges of Infusion

    Science.gov (United States)

    Hale, J. P.; Zimmerman, P.; Kukkala, G.; Guerrero, J.; Kobryn, P.; Puchek, B.; Bisconti, M.; Baldwin, C.; Mulpuri, M.

    2017-01-01

    Digital model-based engineering (DMbE) is the use of digital artifacts, digital environments, and digital tools in the performance of engineering functions. DMbE is intended to allow an organization to progress from documentation-based engineering methods to digital methods that may provide greater flexibility, agility, and efficiency. The term 'DMbE' was developed as part of an effort by the Model-Based Systems Engineering (MBSE) Infusion Task team to identify what government organizations might expect in the course of moving to or infusing MBSE into their organizations. The Task team was established by the Interagency Working Group on Engineering Complex Systems, an informal collaboration among government systems engineering organizations. This Technical Memorandum (TM) discusses the work of the MBSE Infusion Task team to date. The Task team identified prerequisites, expectations, initial challenges, and recommendations for areas of study to pursue, as well as examples of efforts already in progress. The team identified the following five expectations associated with DMbE infusion, discussed further in this TM: (1) Informed decision making through increased transparency, and greater insight. (2) Enhanced communication. (3) Increased understanding for greater flexibility/adaptability in design. (4) Increased confidence that the capability will perform as expected. (5) Increased efficiency. The team identified the following seven challenges an organization might encounter when looking to infuse DMbE: (1) Assessing value added to the organization. Not all DMbE practices will be applicable to every situation in every organization, and not all implementations will have positive results. (2) Overcoming organizational and cultural hurdles. (3) Adopting contractual practices and technical data management. (4) Redefining configuration management. The DMbE environment changes the range of configuration information to be managed to include performance and design models

  1. National Map Data Base On Landslide Prerequisites In Clay and Silt Areas - Development of Prototype

    Science.gov (United States)

    Viberg, Leif

    Swedish geotechnical institute, SGI, has in co-operation with Swedish geologic survey, Lantmateriet (land surveying) and Swedish Rescue Service developed a theme database on landslide prerequisites in clay and silt areas. The work is carried out on commission of the Swedish government. A report with suggestions for production of the database has been delivered to the government. The database is a prototype, which has been tested in an area in northern Sweden. Recommended presentation map scale is about 1:50 000. Distribution of the database via Internet is discussed. The aim of the database is to use it as a modern planning tool in combination with other databases, e g databases on flooding prognoses. The main use is supposed to be in early planning stages, e g for new building and infrastructure development and for risk analyses. The database can also be used in more acute cases, e g for risk analyses and rescue operations in connection with flooding over large areas. Users are supposed to be municipal and county planners and rescue services, infrastructure planners, consultants and assurance companies. The database is constructed by combination of two existing databases: Elevation data and soil map data. The investigation area is divided into three zones with different stability criteria: 1. Clay and silt in sloping ground or adjoining water. 2. Clay and silt in flat ground. 3. Rock and other soils than clay and silt. The geometrical and soil criteria for the zones are specified in an algoritm, that will do the job to sort out the different zones. The algoritm is thereby using data from the elevation and soil databases. The investigation area is divided into cells (raster format) with 5 x 5 m side length. Different algoritms had to be developed before reasonable calculation time was reached. The theme may be presented on screen or as a map plot. A prototype map has been produced for the test area. A description is accompanying the map. The database is suggested

  2. Can donor aid for health be effective in a poor country? Assessment of prerequisites for aid effectiveness in Uganda.

    Science.gov (United States)

    Juliet, Nabyonga Orem; Freddie, Ssengooba; Okuonzi, Sam

    2009-10-22

    Inadequate funding for health is a challenge to attaining health-related Millennium Development Goals. Significant increase in health funding was recommended by the Commission for Macroeconomics and Health. Indeed Official Development Assistance has increased significantly in Uganda. However, the effectiveness of donor aid has come under greater scrutiny. This paper scrutinizes the prerequisites for aid effectiveness. The objective of the study was to assess the prerequisites for effectiveness of donor aid, specifically, its proportion to overall health funding, predictability, comprehensiveness, alignment to country priorities, and channeling mechanisms. Secondary data obtained from various official reports and surveys were analyzed against the variables mentioned under objectives. This was augmented by observations and participation in discussions with all stakeholders to discuss sector performance including health financing. Between 2004-2007, the level of aid increased from US$6 per capita to US$11. Aid was found to be unpredictable with expenditure varying between 174-8722;360 percent from budgets. More than 50% of aid was found to be off budget and unavailable for comprehensive planning. There was disproportionate funding for some items such as drugs. Key health system elements such as human resources and infrastructure have not been given due attention in investment. The government's health funding from domestic sources grew only modestly which did not guarantee fiscal sustainability. Although donor aid is significant there is need to invest in the prerequisites that would guarantee its effective use.

  3. Characterization of precipitates in X12CrMoWVNbN10-1-1 steel during heat treatment

    Science.gov (United States)

    Tao, Xingang; Gu, Jianfeng; Han, Lizhan

    2014-09-01

    The characterization of precipitates in X12CrMoWVNbN10-1-1 steel during the heat treatment was carried out for revealing the evolution of the precipitates. In addition to other microstructural parameters (such as dislocation and subgrains), the precipitate also plays an important role for microstructural stability which is a prerequisite for long term creep strength. In this paper, the precipitates during the heat treatment for this steel were characterized using physicochemical phase analyses and transmission electron microscopy. It was found that the Fe-rich M3C carbides and Nb-rich MX particles were detected in the samples cooled in furnace from austenitization at 1080 °C for 16 h. However, after water cooling, only Nb-rich MX particles existed. During tempering at 570 °C for 18 h, the formation of Cr-rich M7C3 was detected but was replaced partially by Cr-rich M23C6. Additional Cr-rich M2N nitride was also found. After two successive tempering (570 °C + 690 °C) for 24 h, Cr-rich M7C3 was completely replaced. The microchemical analyses of the extracted residues during heat treatment were also discussed. The results gave rise to an indication that the precipitation of precipitates nearly completed in first tempering and the transformation from Cr-rich M7C3 to Cr-rich M23C6 mainly occurred in the second tempering.

  4. Organizational prerequisites for the preservation of library collections in monastery libraries

    Directory of Open Access Journals (Sweden)

    Maja Krtalić

    2012-02-01

    Full Text Available The aim of the paper is to investigate the preservation of written heritage in monastery libraries from legislative, institutional and organizational perspectives, and establish the necessary organizational prerequisites for improvement. Setting off from the presupposition that the library collections of monastery libraries are of immense cultural value, and can therefore be considered cultural good and part of Croatian written heritage, the paper discussed the need for a systematic approach to its protection, both on the operative level, in libraries themselves, and on the strategic level, by the authorities and other relevant institutions in the Republic of Croatia. In addition to the analysis of the legal and institutional frameworks and library collections preservation projects, three case studies were conducted in Franciscan monasteries in Mostar, Požega and Zadar, including interviews with their managers and one subject from the Croatian Institute of Librarianship. The case study aimed to investigate the context of the preservation of library collections in monastery libraries and provide answers to the following questions: how is the preservation in monastery libraries defined; how does it differ from the preservation in other libraries, and how is the preservation of collections in these libraries organized on institutional, local, and national levels? The research sets off from several core presuppositions: monastery libraries have valuable collections of Croatian and European written heritage; the heritage collections in monastery libraries are not investigated, organized, protected or presented at an adequate level; the responsibility for its preservation is not clearly assigned, there is not enough staff trained for preservation; the improvements in preservation and availability of library collections in monastery libraries should result from a better organization and management of the heritage preservation system in monastery

  5. Multivariate clustering of reindeer herding districts in Sweden according to range prerequisites for reindeer husbandry

    Directory of Open Access Journals (Sweden)

    Henrik Lundqvist

    2009-01-01

    Full Text Available The 51 reindeer herding districts in Sweden vary in productivity and prerequisites for reindeer herding. In this study we characterize and group reindeer herding districts based on relevant factors affecting reindeer productivity, i.e. topography, vegetation, forage value, habitat fragmentation and reachability, as well as season lengths, snow fall, ice-crust probability, and insect harassment, totally quantified in 15 variables. The herding districts were grouped into seven main groups and three single outliers through cluster analyses. The largest group, consisting of 14 herding districts, was further divided into four subgroups. The range properties of herding districts and groups of districts were characterized through principal component analyses. By comparisons of the suggested grouping of herding districts with existing administrative divisions, these appeared not to coincide. A new division of herding districts into six administrative sets of districts was suggested in order to improve administrative planning and management of the reindeer herding industry. The results also give possibilities for projections of alterations caused by an upcoming global climate change. Large scale investigations using geographical information systems (GIS and meteorological data would be helpful for administrative purposes, both nationally and internationally, as science-based decision tools in legislative, economical, ecological and structural assessments. Abstract in Swedish / Sammanfattning: Multivariat gruppering av svenska samebyar baserat på renbetesmarkernas grundförutsettningar Svenska renskötselområdet består av 51 samebyar som varierar i produktivitet och förutsättningar för renskötsel. Vi analyserade variationen mellan samebyar med avseende på 15 variabler som beskriver topografi, vegetation, betesvärde, fragmentering av betesmarker, klimat, skareförekomst och aktivitet av parasiterande insekter och vi föreslår en indelning av

  6. Density of Liquid Ni-Cr Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of liquid Ni-Cr alloy was measured by a modified sessile drop method. The density of liquid Ni-Cr alloywas found to decrease with increasing temperature and Cr concentration in the alloy. The molar volume of liquidNi-Cr alloy increases with increasing the Cr concentration in the alloy. The molar volume of Ni-Cr alloy determinedin the present work shows a positive deviation from the linear molar volume.

  7. HFO operation with CR injection

    Energy Technology Data Exchange (ETDEWEB)

    Poensgen, Christian [MAN-Diesel und Turbo SE, Augsburg (Germany)

    2011-07-01

    In 1996 MAN Diesel and Turbo SE started the development of a CR-system for medium speed engines for HFO operation up to fuel viscosity of 700 cSt. 2004 the first field test engine, a 7L 32/40 GenSet was put into service as a retrofit and collected up to now more than 20.000 running hours operated on HFO on a large container vessel. Meanwhile several L32/40 CR GenSets, L32/44 CR, V48/60 CR and L21/31 CR engines collected more than 100000 running hours in HFO operation before MAN Diesel started up the serial production of the new 32/44 CR and 48/60 CR engines. All of these engines are still in service. The paper will give an overview about the field experience and countermeasures which were necessary to develop a reliable product which fulfills the customers' demands concerning low fuel oil consumption, invisible smoke over the whole load range, low emission levels and maintenance costs. The experience was made in a wide range of applications such as GenSet, Cruise Vessel main propulsion and ferry main propulsion running 24h/day. The field test engines reached an availability of more than 90% per year. The paper also will point out the win/win situation for the the manufacturer and customer to participate in the development of the CR technology. For customers satisfaction MAN Diesel provides help for easy handling like online access per satellite connection, easy leakage detection and operator training at site or at the new built academies. The flexibility of the CR-system is the base frame for the future development of engines which fulfills IMO TIER II and IMO TIER III with high efficiency. The necessary reliability, a must, has been proven in the field under real conditions. (orig.)

  8. Electret properties of CR-39

    Energy Technology Data Exchange (ETDEWEB)

    Makovicka, L.; Moliton, A.; Guille, B.; Teyssier, J.L.

    1987-01-01

    The behaviour of CR-39 (a solid track detector) as an electret is compared with other classical electret materials (Teflon, Mylar). The initial charge obtained, principally by a corona method, and its decay have been studied; the result for the charge of CR-39 is similar to that for other polymer electrets and the decay is intermediate between that of Teflon and Mylar. Some results of X ray and neutron irradiations are then presented. They show significant responses of CR-39 subjected to X ray beams of approximately 10/sup -2/ Gy.

  9. Evaluation of Prerequisite Programs Implementation and Hygiene Practices at Social Food Services through Audits and Microbiological Surveillance.

    Science.gov (United States)

    Garayoa, Roncesvalles; Yánez, Nathaly; Díez-Leturia, María; Bes-Rastrollo, Maira; Vitas, Ana Isabel

    2016-04-01

    Prerequisite programs are considered the most efficient tool for a successful implementation of self-control systems to ensure food safety. The main objective of this study was to evaluate the implementation of these programs in 15 catering services located in Navarra and the Basque Country (regions in northern Spain), through on-site audits and microbiological analyses. The implementation of the prerequisite program was incomplete in 60% of the sample. The unobserved temperature control during both the storage and preparation of meals in 20% of the kitchens reveals misunderstanding in the importance of checking these critical control points. A high level of food safety and hygiene (absence of pathogens) was observed in the analyzed meals, while 27.8% of the tested surfaces exceeded the established limit for total mesophilic aerobic microorganisms (≤100 CFU/25 cm²). The group of hand-contact surfaces (oven door handles and aprons) showed the highest level of total mesophilic aerobic microorganisms and Enterobacteriaceae, and the differences observed with respect to the food-contact surfaces (work and distribution utensils) were statistically significant (P food workers' hands, lower levels of microorganisms were observed in the handlers wearing gloves (that is, for Staphylococcus spp we identified 43 CFU/cm2 on average compared with 4 CFU/cm2 (P food handlers, through specific activities such as informal meetings and theoretical-practical sessions adapted to the characteristics of each establishment.

  10. Optimizing Simulated Multidisciplinary Team Training of Pediatric Emergencies: An Evaluation of Prerequisites for Transfer of Skills to Clinical Practice

    Directory of Open Access Journals (Sweden)

    E. H. A. J. Coolen

    2015-01-01

    Full Text Available Introduction. Multidisciplinary simulation-based team training (STT provides a powerful training method to train technical and team skills during emergencies. Effectiveness of STT depends on transfer of learned skills to clinical practice. In this study we examined three important prerequisites to enhance transfer from STT into clinical practice, intervention readiness, realism, and performance self-efficacy. Methods. For the quantitative part of the study, 131 participants (pediatric nurses and physicians were asked to fill out an online questionnaire before and after training. For the qualitative part of the study we organized three one-hour focus group sessions in which participants were interviewed on attitude, realism, and self-efficacy. Results. Providing adequate preparation material and extensive debriefing of scenarios is important in creating this positive learning experience. The perspective of realism depends strongly on setting and learning goals. During STT team assembly and role playing can become more important to participants, while physical aspects become less important. Performance self-efficacy for all participants increases significantly (P<0.05 regarding team skills. Conclusions. STT can be a very positive multidisciplinary learning experience, which creates the possibility of enhancing confidence, skills, and team performance within the clinical context. STT combines three important prerequisites for transfer of training to take place.

  11. Kinetics of Cr(III) and Cr(VI) removal from water by two floating macrophytes.

    Science.gov (United States)

    Maine, M A; Hadad, H R; Sánchez, G; Caffaratti, S; Pedro, M C

    2016-01-01

    The aim of this work was to compare Cr(III) and Cr(VI) removal kinetics from water by Pistia stratiotes and Salvinia herzogii. The accumulation in plant tissues and the effects of both Cr forms on plant growth were also evaluated. Plants were exposed to 2 and 6 mg L(-1) of Cr(III) or Cr(VI) during 30 days. At the end of the experiment, Cr(VI) removal percentages were significantly lower than those obtained for Cr(III) for both macrophytes. Cr(III) removal kinetics involved a fast and a slow component. The fast component was primarily responsible for Cr(III) removal while Cr(VI) removal kinetics involved only a slow process. Cr accumulated principally in the roots. In the Cr(VI) treatments a higher translocation from roots to aerial parts than in Cr(III) treatments was observed. Both macrophytes demonstrated a high ability to remove Cr(III) but not Cr(VI). Cr(III) inhibited the growth at the highest studied concentration of both macrophytes while Cr(VI) caused senescence. These results have important implications in the use of constructed wetlands for secondary industrial wastewater treatment. Common primary treatments of effluents containing Cr(VI) consists in its reduction to Cr(III). Cr(III) concentrations in these effluents are normally below the highest studied concentrations in this work.

  12. Cu-Cr Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Need, Ryan F. [Los Alamos National Laboratory

    2012-08-09

    Cu-Cr alloys are part of a class of face-centered cubic (FCC)-body-centered cubic (BCC) composites that includes similar alloys, such as Cu-Nb and Cu-Ta. When heavily deformed, these FCC-BCC materials create 'in situ' composites with a characteristic structure-nanoscale BCC filaments in a ductile FCC matrix. The strength of these composites is vastly greater than predicted by the rule of mixtures, and has been shown to be inversely proportional to the filament spacing. Lower raw materials costs suggest that Cu-Cr alloys may offer more economical solution to high-strength, high-conductivity wire than either their Nb or Ta counterparts. However, Cr is also more brittle and soluble in Cu than Nb or Ta. These qualities necessitate thermal treatments to remove solute atoms from the Cu matrix, improve conductivity, and maintain the ductility of the Cr filaments. Through the use of different thermomechanical processing routes or the addition of select dopants, alloys with strength in excess of 1 GPa at 70% IACS have been achieved. To date, previous research on Cu-Cr alloys has focused on a relatively small number of alloy compositions and processing methods while the effects of dopants and ageing treatments have only been studied independently. Consequently, there remains considerable opportunity for the development and optimization of these alloys as a leading high-strength, high-conductivity material.

  13. Bacterial Reduction of Toxic Cr(Ⅵ)into Cr(Ⅲ)%利用细菌还原有毒Cr(Ⅵ)为Cr(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    Muhammad Faisal; Shahida Hasnain

    2004-01-01

    Two chromium-resistant bacterial strains CrT-1 and CrT-13,which can tolerate K2 CrO4 up to 40 mg·mL-1 on nutrient agar,25 mg·mL-1 K2 CrO4 in nutrient broth,and up to 10 mg·mL-1 in acetate-minimal media,were used in this study.On the basis of 16S rRNA,strain CrT-1 was identified as Ochrobactrum intermedium and CrT-13 as Brevibacterium sp..Uptake of chromate was greater in living cells than in heat-killed cells.Ochrobactrum intermedium CrT-1 reduced 73% and 41% of Cr(Ⅵ)while Brevibacterium CrT-13 reduced 62% and 48% Cr(Ⅵ) at an initial chromate concentration of 750,and 1500 μg·mL-1,after 96 hours with an inoculum size of 9.6×107 cells·mL-1.Different heavy metals at low concentrations did not affect the reduction potential of the strains significantly.Ochrobactrum intermedium CrT-1 reduced 84% and 65% while Brevibacterium CrT-13 reduced 60% and 44% of Cr(Ⅵ)at an initial Cr(Ⅵ)concentration of 250 and 500 μg·mL-1,espectively,in an industrial effluent sample.

  14. Building the effective innovation policy in the regions of the Russian Federation as a prerequisite for socio-economic growth

    Directory of Open Access Journals (Sweden)

    Irina Markovna Golova

    2011-06-01

    Full Text Available The basic problems and contradictions of regional innovation policy formation in Russia are revealed. The need to move the Russian economy on an innovative way of development is seen as a condition of economic security. With the usage of global experience, priorities in innovational activity of Russian companies and measures to address systemic gaps between science and industry are grounded. Particular attention is paid to the legal aspects of the state innovational policy. Methodological approaches to the formation of regional innovational policy in the Russian Federation, taking into account the spatial distribution of the scientific, technical and production capacities of the country, their state and structure are revealed. The necessity of a major upgrade of the existing system of intergovernmental relations as a prerequisite for building a functioning innovation system is substantiated. The proposals on division of competence between the Federation and the subjects of the Russian Federation in the regulation of relations in science, technology and innovations are given.

  15. Biofilm formation is not a prerequisite for production of the antibacterial compound tropodithietic acid in Phaeobacter inhibens DSM17395

    DEFF Research Database (Denmark)

    Prol García, María Jesús; D'Alvise, Paul; Rygaard, Anita Mac

    2014-01-01

    Aims The goal of this study was to investigate if biofilm formation on population level is a physiological requirement for antagonism in Phaeobacter inhibens DSM17395, since the antibiotic compound tropodithietic acid (TDA) is produced by several Roseobacter clade species during growth as multice......Aims The goal of this study was to investigate if biofilm formation on population level is a physiological requirement for antagonism in Phaeobacter inhibens DSM17395, since the antibiotic compound tropodithietic acid (TDA) is produced by several Roseobacter clade species during growth...... that are likely involved in EPS/LPS production, motility and chemotaxis, and redox regulation play a role in biofilm formation and/or adhesion in P. inhibens DSM17395. Conclusions Cell aggregation and biofilm formation are not physiological prerequisites for TDA production. Significance and Impact of the Study...

  16. High temperature wear performance of HVOF-sprayed Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr hardmetal coatings

    Science.gov (United States)

    Zhou, Wuxi; Zhou, Kesong; Li, Yuxi; Deng, Chunming; Zeng, Keli

    2017-09-01

    A novel Cr3C2-WC-NiCoCrMo and commercial Cr3C2-NiCr thermal spray-grade powders with particle size of -45 + 15 μm were prepared by an agglomeration and sintering process. Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr coatings were deposited by high velocity oxygen fuel (HVOF) spraying. The fundamental properties of both coatings were evaluated and friction wear test against Al2O3 counterbodies of both coatings at high temperatures (450 °C, 550 °C, 650 °C) were carried out ball-on-disk high temperature tribometer. All specimens were characterized by optical microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) and 3D non-contact surface mapping profiler. The results have shown that the Cr3C2-WC-NiCoCrMo coating exhibited lower porosity, higher micro-hardness compared to the Cr3C2-NiCr coating. The Cr3C2-WC-NiCoCrMo coating also exhibited better wear resistance and higher friction coefficient compared to the Cr3C2-NiCr coating when sliding against the Al2O3 counterpart. Wear rates of both coatings increased with raising temperature. Both coatings experienced abrasive wear; hard phase particles (WC and Cr3C2) with different sizes, distributed in the matrix phase, will effectively improve the resistance against wear at high temperatures.

  17. Stabilizing CrO by epitaxial growth

    NARCIS (Netherlands)

    Rogojanu, Oana Corina; Sawatzky, G.A; Tjeng, L.H

    2002-01-01

    This thesis describes the efforts to stabilize chromium monoxide (CrO) as a thin epitaxial film on various substrates. The most stable and common oxidation phase for chromium is in chromium sesquioxide (Cr2O3). CrO does not exist as a bulk material in nature, therefore we have to grow it in a

  18. Inhibition of corrosion of zinc by Cr(VI)and Cr(III) treatments

    NARCIS (Netherlands)

    Zhang, X.; Bos, C. van den; Hovestad, A.; Terryn, H.; Wit, J.H.W. de

    2007-01-01

    The corrosion behavior of Cr(VI) and Cr(III) treated zinc has been studied using scanning Kelvin probe (SKP), potentiodynamic polarization and elctrochemical impedance spectroscopy (EIS). The Volta potentials measured on the Cr(VI) or the CR(III)-A treated zinc area by SKP in a humid chamber are

  19. Drying Effects on Corrosion Properties of Cr(VI) and Cr(III) Treated Electrogalvanized Steel

    NARCIS (Netherlands)

    Zhang, X.; Van den Bos, C.; Sloof, W.G.; Hovestad, A.; Terryn, H.; De Wit, J.H.W.

    2006-01-01

    Drying effects on corrosion performance of Cr(VI)- and Cr(III)-treated electro-galvanized steel have been studied in NaCl solution using potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The Cr(VI) and the Cr(III) treated specimens were dried at three different

  20. Inhibition of corrosion of zinc by Cr(VI)and Cr(III) treatments

    NARCIS (Netherlands)

    Zhang, X.; Bos, C. van den; Hovestad, A.; Terryn, H.; Wit, J.H.W. de

    2007-01-01

    The corrosion behavior of Cr(VI) and Cr(III) treated zinc has been studied using scanning Kelvin probe (SKP), potentiodynamic polarization and elctrochemical impedance spectroscopy (EIS). The Volta potentials measured on the Cr(VI) or the CR(III)-A treated zinc area by SKP in a humid chamber are mor

  1. Drying Effects on Corrosion Properties of Cr(VI) and Cr(III) Treated Electrogalvanized Steel

    NARCIS (Netherlands)

    Zhang, X.; Van den Bos, C.; Sloof, W.G.; Hovestad, A.; Terryn, H.; De Wit, J.H.W.

    2006-01-01

    Drying effects on corrosion performance of Cr(VI)- and Cr(III)-treated electro-galvanized steel have been studied in NaCl solution using potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The Cr(VI) and the Cr(III) treated specimens were dried at three different temperatu

  2. Black Cr/a-Cr2O3 nanoparticles based solar absorbers

    CSIR Research Space (South Africa)

    Khamlich, S

    2012-01-01

    Full Text Available in the literature for samples having the stoichiometric a-Cr2O3. This band is associated with Cr?O stretching modes, more accurately, anti-symmetrical stretching in Cr2O3. This vibra- tional mode is due to various combinations of O2� and Cr3? displacements...

  3. O Crédito

    OpenAIRE

    Santos, Cláudia Barreto dos

    2012-01-01

    O crédito é elemento de fundamental importância para o crescimento econômico de um país. Contudo, na história brasileira recente, por vezes, ele tem sido ressaltado, principalmente para o pequeno investidor, como um mal a ser evitado; uma armadilha capaz de levar à bancarrota pessoas e empresas. Na verdade, é preciso entender que a oferta de crédito e as condições para sua obtenção estão diretamente vinculadas à política monetária do governo e às perspectivas de crescimento econômico. Este ar...

  4. The CR-Marketing Strategy

    OpenAIRE

    Pricop Oliver Constantin

    2011-01-01

    The Customer Relationship- Marketing supposes the adaptation of the marketing mix from the customers’ and the market’s perspective. Thus, the 4 P (product, price, place, promotion) must become 4 D (desired by consumers, distinctive from the competition, deliverable by the company, durable over time) respectively 4C (the buyer with his requirements and desires, the cost paid by the buyer, the convenience of the acquisition, the communication with the customers. The CR-Marketing strategy compri...

  5. Characterization of precipitates in X12CrMoWVNbN10-1-1 steel during heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Xingang; Gu, Jianfeng, E-mail: gujf@sjtu.edu.cn; Han, Lizhan

    2014-09-15

    Highlights: • We characterize precipitates by physicochemical phase analysis, XRD, TEM, and etc. • Precipitation sequence of secondary phase during heat treatment has been revealed. • Carbide precipitation behavior explains the rationality of heat treatment process. - Abstract: The characterization of precipitates in X12CrMoWVNbN10-1-1 steel during the heat treatment was carried out for revealing the evolution of the precipitates. In addition to other microstructural parameters (such as dislocation and subgrains), the precipitate also plays an important role for microstructural stability which is a prerequisite for long term creep strength. In this paper, the precipitates during the heat treatment for this steel were characterized using physicochemical phase analyses and transmission electron microscopy. It was found that the Fe-rich M{sub 3}C carbides and Nb-rich MX particles were detected in the samples cooled in furnace from austenitization at 1080 °C for 16 h. However, after water cooling, only Nb-rich MX particles existed. During tempering at 570 °C for 18 h, the formation of Cr-rich M{sub 7}C{sub 3} was detected but was replaced partially by Cr-rich M{sub 23}C{sub 6}. Additional Cr-rich M{sub 2}N nitride was also found. After two successive tempering (570 °C + 690 °C) for 24 h, Cr-rich M{sub 7}C{sub 3} was completely replaced. The microchemical analyses of the extracted residues during heat treatment were also discussed. The results gave rise to an indication that the precipitation of precipitates nearly completed in first tempering and the transformation from Cr-rich M{sub 7}C{sub 3} to Cr-rich M{sub 23}C{sub 6} mainly occurred in the second tempering.

  6. Effectiveness of prerequisites and the HACCP plan in the control of microbial contamination in ice cream and cheese companies.

    Science.gov (United States)

    Domenech, Eva; Amorós, José Antonio; Escriche, Isabel

    2013-03-01

    In food safety, implementation of prerequisites and application of Hazard Analysis and Critical Control Points (HACCP) guarantee the control of processes, and microbiological criteria permit validation of their effectiveness. With these aims in mind, this article presents the results obtained by the official control carried out by the Valencian administration in ice cream and cheese companies, located in the Xativa/Ontinyente area (Valencian region, Spain) in the period between 2005 and 2010. The audits of Good Hygienic Practices (GHP) and HACCP show that "Structure & Design" followed by "Hygiene & Cleaning" and "Traceability" were the evaluated items with most nonconformities. Pathogenic microorganisms were not found in any of the final products analyzed. Microorganism indicators of unhygienic conditions were present in 100% of the analyses; however, 87.98% of them had low levels, which did not exceed the microbiological criteria. These results highlight the general good effectiveness of the safety management systems implemented and emphasize that companies and official control must continue working in order to guarantee the consumers' welfare.

  7. The Prerequisite of Personal Guilt and the Duty to Know the Law in the Light of Article 32 ICC Statute

    Directory of Open Access Journals (Sweden)

    Stefanie Bock

    2013-09-01

    Full Text Available In international criminal law, personal guilt is a basic prerequisite for criminal liability. A guilty verdict requires at least a psychological relation between the actor and the act, i.e., the actor must fulfil the actus reus of the offence with intent and knowledge. It is, however, a contested issue if this also means that the defendant must have been aware of the criminality of his action. At first glance, the ICC Statute seems to answer this question in the negative: it adopts a narrow understanding of the mens rea requirement which does not include, as a rule, consciousness of the legal wrong, and admits mistakes of law as a valid defence only if they – by way of an exception – negate the required mens rea. This restrictive approach does not, however, have a solid basis in comparative law. Moreover, given the complexity of at least some war crime provisions it seems highly questionable to punish persons who honestly but wrongfully believe that their conduct is lawful without taking into account whether they can be blamed for their ignorance of the law. Rather, the principle of personal guilt understood in a broad and comprehensive sense calls for a more flexible approach towards mistakes of law having due regard to the reasonableness or avoidability of the misconception.

  8. Individual Pheromone Signature in Males: Prerequisite for Pheromone-Mediated Mate Assessment in the Central American Locust, Schistocerca Piceifrons.

    Science.gov (United States)

    Stahr, Christiane; Seidelmann, Karsten

    2016-12-01

    Living in high-density groups of animals has advantages and disadvantages for mating. The advantage of facilitated mate finding is compromised by difficulties in protecting a suitable partner from competitors. Thus, males regularly are faced with increased competition for sperm, and females with harassment by males at high population densities. To cope with these problems, mating tactics and mate choice mechanisms have to be adjusted. An adaptation to gregarious condition observed in locusts includes the use of male-emitted pheromones. Males of the Central American locust, Schistocerca piceifrons, release sex-specific volatiles, which were identified as phenethyl alcohol (synonym: phenyl-ethyl-alcohol, 2-phenyl-1-ethanol, 2-phenylethanol, PEA), (Z)-3-nonen-1-ol (3-Nol), and (Z)-2-octen-1-ol (2-Ool). The emission of the two major compounds, PEA and 3-Nol, was restricted to crowded conditions. Furthermore, the release of both volatiles was coupled to males reaching sexual maturity, indicating a function in reproductive behavior. However, neither the single substances nor their mixtures were attractive or repellent to the locusts. Instead, females prefer the sperm of high pheromone-emitting males to fertilize their ova. In this way, the male-specific volatiles act as mate assessment pheromones utilized in a context of cryptic female choice. This function is well supported by the highly variable but individual-specific emission rates of the three compounds. Schistocerca piceifrons males release a virtually unique personal pheromone signature, a prerequisite for mate assessment pheromones.

  9. New nanosized catalytic membrane reactors for hydrogenation with stored hydrogen: Prerequisites and the experimental basis for their creation

    Science.gov (United States)

    Soldatov, A. P.; Tsodikov, M. V.; Parenago, O. P.; Teplyakov, V. V.

    2010-12-01

    The prerequisites and prospects for creating a new generation of nanosized membrane reactors are considered. For the first time, hydrogenation reactions take place in ceramic membrane pores with hydrogen adsorbed beforehand in mono- and multilayered oriented carbon nanotubes with graphene walls (OCNTGs) formed on the internal pore surface. It is shown for Trumem microfiltration membranes with D avg ˜130 nm that oxidation reactions of CO on a Cu0.03Ti0.97O2 ± δ catalyst and the oxidative conversion of methane into synthesis gas and light hydrocarbons on La + Ce/MgO are considerably enhanced when they occur in membranes. Regularities of hydrogen adsorption, storage, and desorption in nanosized membrane reactors are investigated through OCNTG formation in Trumem ultrafiltration membrane pores with D avg = 50 and 90 nm and their saturation with hydrogen at a pressure of 10-13 MPa. It is shown that the amount of adsorbed hydrogen reaches 14.0% of OCNTG mass. Using thermogravimetric analysis in combination with mass-spectrometric analysis, hydrogen adsorption in OCNTG is first determined and its desorption is found to proceed at atmospheric pressure at a temperature of ˜175°C. It is shown that adsorbed hydrogen affects the transport properties of the membranes, reducing their efficiency with respect to liquids by 4-26 times. This is indirect confirmation of its high activity, due apparently the dissociative mechanism of adsorption.

  10. Biofilm formation is not a prerequisite for production of the antibacterial compound tropodithietic acid in Phaeobacter inhibens DSM17395.

    Science.gov (United States)

    Prol García, M J; D'Alvise, P W; Rygaard, A M; Gram, L

    2014-12-01

    The goal of this study was to investigate if biofilm formation on population level is a physiological requirement for antagonism in Phaeobacter inhibens DSM17395, since the antibiotic compound tropodithietic acid (TDA) is produced by several Roseobacter clade species during growth as multicellular aggregates or biofilms at the air-liquid interface and is induced on single cell level upon attachment. A mutant library was created by Tn5 transposon insertion and 22 TDA-positive (brown) mutants with decreased biofilm formation or adhesion, and eight TDA-negative (white) mutants with increased biofilm formation or adhesion were selected. None of the selected biofilm-overproducing white mutants showed any antibiotic activity, while all brown mutants with reduced or disabled biofilm formation produced the antibacterial compound. Sequencing analysis indicated that genes that are likely involved in EPS/LPS production, motility and chemotaxis, and redox regulation play a role in biofilm formation and/or adhesion in P. inhibens DSM17395. Cell aggregation and biofilm formation are not physiological prerequisites for TDA production. This study contributes to the understanding of TDA production in P. inhibens, which has great potential as a probiotic in marine larviculture. © 2014 The Society for Applied Microbiology.

  11. Video Self-Modeling in Children with Autism: A Pilot Study Validating Prerequisite Skills and Extending the Utilization of VSM across Skill Sets

    Science.gov (United States)

    Williamson, Robert L.; Casey, Laura B.; Robertson, Janna Siegel; Buggey, Tom

    2013-01-01

    Given the recent interest in the use of video self-modeling (VSM) to provide instruction within iPod apps and other pieces of handheld mobile assistive technologies, investigating appropriate prerequisite skills for effective use of this intervention is particularly timely and relevant. To provide additional information regarding the efficacy of…

  12. Video Self-Modeling in Children with Autism: A Pilot Study Validating Prerequisite Skills and Extending the Utilization of VSM across Skill Sets

    Science.gov (United States)

    Williamson, Robert L.; Casey, Laura B.; Robertson, Janna Siegel; Buggey, Tom

    2013-01-01

    Given the recent interest in the use of video self-modeling (VSM) to provide instruction within iPod apps and other pieces of handheld mobile assistive technologies, investigating appropriate prerequisite skills for effective use of this intervention is particularly timely and relevant. To provide additional information regarding the efficacy of…

  13. Formation of aligned CrN nanoclusters in Cr-delta-doped GaN

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Y K; Kimura, S; Emura, S; Hasegawa, S; Asahi, H [Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)], E-mail: zhou21@sanken.osaka-u.ac.jp

    2009-02-11

    Cr-delta-doped GaN layers were grown by radio-frequency plasma-assisted molecular-beam epitaxy on GaN template substrates. Cr flux was supplied without nitrogen flow during Cr-delta-doping. Cr incorporation into a narrow thin layer region was confirmed with the depth profile measured by secondary ion mass spectrometry. Structural properties and Cr atom alignments were studied with transmission electron microscopy. It was found that Cr-delta-doped GaN layers were coherently grown with Cr or CrGa nanoclusters in the delta-doped region for low temperature growth (350, 500 deg. C). It was also found that aligned CrN nanoclusters (approximately 5 nm vertical thickness) with NaCl-type structure were formed in the delta-doped region for the growth at 700 deg. C.

  14. Chromium-chromium interaction in a binuclear mixed-valent Cr(I)-Cr(II) complex.

    Science.gov (United States)

    Alzamly, Ahmed; Gorelsky, Serge I; Gambarotta, Sandro; Korobkov, Ilia; Le Roy, Jennifer; Murugesu, Muralee

    2014-11-03

    A mixed-valent Cr(I)-Cr(II) binuclear complex, {κ(1),κ(2),κ(3)-N,P,P-cyclo[(Ph)PCH2N(CH2Ph)CH2]}2(CrCl2)[Cr(μ-Cl)(AlClMe2)]·4toluene (1), of a P2N2 cyclic ligand was obtained upon treatment of the chromium precursor with alkylaluminum. Complex 1 was accessible from either its trivalent or divalent precursors, and density functional theory calculations revealed the presence of only σ- and π-orbital interactions in the Cr-Cr bond.

  15. TRAIL-Induced Caspase Activation Is a Prerequisite for Activation of the Endoplasmic Reticulum Stress-Induced Signal Transduction Pathways.

    Science.gov (United States)

    Lee, Dae-Hee; Sung, Ki Sa; Guo, Zong Sheng; Kwon, William Taehyung; Bartlett, David L; Oh, Sang Cheul; Kwon, Yong Tae; Lee, Yong J

    2016-05-01

    It is well known that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis can be initially triggered by surface death receptors (the extrinsic pathway) and subsequently amplified through mitochondrial dysfunction (the intrinsic pathway). However, little is known about signaling pathways activated by the TRAIL-induced endoplasmic reticulum (ER) stress response. In this study, we report that TRAIL-induced apoptosis is associated with the endoplasmic reticulum (ER) stress response. Human colorectal carcinoma HCT116 cells were treated with TRAIL and the ER stress-induced signal transduction pathway was investigated. During TRAIL treatment, expression of ER stress marker genes, in particular the BiP (binding immunoglobulin protein) gene, was increased and activation of the PERK (PKR-like ER kinase)-eIF2α (eukaryotic initiation factor 2α)-ATF4 (activating transcription factor 4)-CHOP (CCAAT-enhancer-binding protein homologous protein) apoptotic signal transduction pathway occurred. Experimental data from use of a siRNA (small interfering RNA) technique, caspase inhibitor, and caspase-3-deficient cell line revealed that TRAIL-induced caspase activation is a prerequisite for the TRAIL-induced ER stress response. TRAIL-induced ER stress was triggered by caspase-8-mediated cleavage of BAP31 (B cell receptor-associated protein 31). The involvement of the proapoptotic PERK-CHOP pathway in TRAIL-induced apoptosis was verified by using a PERK knockout (PERK(-/-)) mouse embryo fibroblast (MEF) cell line and a CHOP(-/-) MEF cell line. These results suggest that TRAIL-induced the activation of ER stress response plays a role in TRAIL-induced apoptotic death.

  16. Health Information Needs and Reliability of Sources Among Nondegree Health Sciences Students: A Prerequisite for Designing eHealth Literacy.

    Science.gov (United States)

    Haruna, Hussein; Tshuma, Ndumiso; Hu, Xiao

    Understanding health information needs and health-seeking behavior is a prerequisite for developing an electronic health information literacy (EHIL) or eHealth literacy program for nondegree health sciences students. At present, interest in researching health information needs and reliable sources paradigms has gained momentum in many countries. However, most studies focus on health professionals and students in higher education institutions. The present study was aimed at providing new insight and filling the existing gap by examining health information needs and reliability of sources among nondegree health sciences students in Tanzania. A cross-sectional study was conducted in 15 conveniently selected health training institutions, where 403 health sciences students were participated. Thirty health sciences students were both purposely and conveniently chosen from each health-training institution. The selected students were pursuing nursing and midwifery, clinical medicine, dentistry, environmental health sciences, pharmacy, and medical laboratory sciences courses. Involved students were either in their first year, second year, or third year of study. Health sciences students' health information needs focus on their educational requirements, clinical practice, and personal information. They use print, human, and electronic health information. They lack eHealth research skills in navigating health information resources and have insufficient facilities for accessing eHealth information, a lack of specialists in health information, high costs for subscription electronic information, and unawareness of the availability of free Internet and other online health-related databases. This study found that nondegree health sciences students have limited skills in EHIL. Thus, designing and incorporating EHIL skills programs into the curriculum of nondegree health sciences students is vital. EHIL is a requirement common to all health settings, learning environments, and

  17. The organic principle of eurasianism and the prerequisite of change of the style of thinking dominating in modern science

    Directory of Open Access Journals (Sweden)

    Koptelova T. I.

    2015-01-01

    Full Text Available In the article, the organic principle of the Euroasian philosophy is studied. The organic principle acts as a basis of special style of thinking and a certain methodology of scientific knowledge here. The Euroasian methodology of studying of development of society allows establishing of the nature of communications between social processes and the phenomena of wildlife. In the article, the most important components of the Euroasian organic principle of thinking are shown: special terminology and possibilities of its application for the description and forecasting of the social phenomena. Prerequisites of change of the style of thinking dominating in modern science are also noted. The author considers advantages of the organic principle of the Euroasian methodology in solution of national political, social-economic and cultural problems and in possible prospects of its use for formation of scientific methodology. The organic principle of thinking creates complex idea of reality, which can appear before us new, party unknown earlier. Lack of division of sensual experience and “pure reason”, irrational and rational in organic thinking is unconditional advantage of organic approach. Organic principle presented by the Euroasian philosophical organization of the beginning of the twentieth century and continued by Lev Gumilev in the theory of ethnogenesis acts as alternative developed in the west of one-dimensional, mechanistic methodology. It can be told with confidence that owning all of variety of intellectual traditions is necessary for the modern humankind to become capable to realize global ecological threats and negative consequences of influence of culture in which ethics of individualism prevails.

  18. Laser properties of yag: Nd, Cr, Ce

    Science.gov (United States)

    Kvapil, J.; Kvapil, Jos; Perner, B.; Kubelka, J.; Mánek, B.; Kubeček, V.

    1984-06-01

    Transient absorption of a long lifetime (≧ 20 s) of YAG: Nd is typical of pure material. It is the main reason of thermal deformation of the laser rods accompanied with power decreases at higher CW input. It may be prevented by an admixture of Fe, Ti or Cr. Using a small admixture (≦ 10-3 wt.%) of Ti or Cr the energy transfer among Nd ions and the gain coefficient may be increased. Cr in a higher concentration absorbs the pumping light and serves as earlier described coactivator (sensitizer) only. Fe impurity fully prevents any increase of the gain of YAG: Nd containing Ti or Cr and causes slow but irreversible degradation of the active parameters. Ce favourably modifies properties of YAG: Nd, Cr. YAG: Nd, Cr, Ce free of iron impurity is advisable active material for powerfull CW lasers.

  19. Cr isotope fractionation factors for Cr(VI) reduction by a metabolically diverse group of bacteria

    Science.gov (United States)

    Basu, Anirban; Johnson, Thomas M.; Sanford, Robert A.

    2014-10-01

    Reduction of Cr(VI) is an important process that determines the geochemical behavior, mobility and bioavailability of Cr in both terrestrial and marine environments. Many metabolically diverse microorganisms possess Cr(VI) reduction capacity. Cr(VI) reduction fractionates Cr isotopes and thus 53Cr/52Cr ratios can be used to monitor Cr(VI) reduction and redox conditions. The magnitude of isotopic fractionation (ε) for a variety of microbial reduction mechanisms must be known for accurate interpretation of observed shifts in 53Cr/52Cr ratios. We determined isotopic fractionation factors for Cr(VI) reduction by metal reducers Geobacter sulfurreducens and Shewanella sp. strain NR, a denitrifying soil bacterium Pseudomonas stutzeri DCP-Ps1, and a sulfate reducer Desulfovibrio vulgaris. All bacteria investigated in this study produced significant Cr isotope fractionation. The fractionation (ε) for G. sulfurreducens, Shewanella sp. (NR), P. stutzeri DCP-Ps1, and D. vulgaris were -3.03‰ ± 0.12‰, -2.17‰ ± 0.22‰, -3.14‰ ± 0.13‰, and -3.01‰ ± 0.11‰, respectively. Despite differences in microbial strains in this study, the ε did not vary significantly except for Shewanella sp. (NR). Our results suggest that strong isotopic fractionation is induced during Cr(VI) reduction under electron donor poor (∼300 μM) conditions.

  20. Biochemical changes in blood under Cr6+

    OpenAIRE

    Kuzenko E.V.; Romaniuk A.M.; Butko H.Yu.; Logvinova H.V.

    2013-01-01

    Background. For the manufacture of dentures many different alloys containing chromium are used. Interaction with oral fluid, organic acids and food, results in formation of Cr3+, Cr6+ ions, but their influence on the whole organism is poorly investigated. Objective. To analyze the biochemical changes in blood plasma during the influence of Cr6+ ions. Methods. 15 animals of experimental group were receiving drinking water with potassium dichromate in a dose of 0,2 mol/l. Rats of control group ...

  1. Thermodynamics of Cr2O3, FeCr2O4, ZnCr2O4 and CoCr2O4

    Energy Technology Data Exchange (ETDEWEB)

    Ziemniak SE, Anovitz LM, Castelli RA, Porter WD

    2007-01-09

    High temperature heat capacity measurements were obtained for Cr{sub 2}O{sub 3}, FeCr{sub 2}O{sub 4}, ZnCr{sub 2}O{sub 4} and CoCr{sub 2}O{sub 4} using a differential scanning calorimeter. These data were combined with previously-available, overlapping heat capacity data at temperatures up to 400 K and fitted to 5-parameter Maier-Kelley C{sub p}(T) equations. Expressions for molar entropy were then derived by suitable integration of the Maier-Kelley equations in combination with recent S{sup o}(298) evaluations. Finally, a database of high temperature equilibrium measurements on the formation of these oxides was constructed and critically evaluated. Gibbs energies of Cr{sub 2}O{sub 3}, FeCr{sub 2}O{sub 4} and CoCr{sub 2}O{sub 4} were referenced by averaging the most reliable results at reference temperatures of 1100, 1400 and 1373 K, respectively, while Gibbs energies for ZnCr{sub 2}O{sub 4} were referenced to the results of Jacob [Thermochim. Acta 15 (1976) 79-87] at 1100 K. Thermodynamic extrapolations from the high temperature reference points to 298.15 K by application of the heat capacity correlations gave {Delta}{sub f}G{sup o}(298) = -1049.96, -1339.40, -1428.35 and -1326.75 kJ mol{sup -1} for Cr{sub 2}O{sub 3}, FeCr{sub 2}O{sub 4}, ZnCr{sub 2}O{sub 4} and CoCr{sub 2}O{sub 4}, respectively.

  2. Cr-Free Metallic-Ceramic Coatings

    Science.gov (United States)

    2014-11-01

    Cr -FREE METALLIC-CERAMIC COATINGS ASETS Defense 2014 Fort Myer, VA, November 18-20, 2014 Bruce McMordie Coatings for Industry 319...SNECMA Alseal® 5K Aluminum-Silicate Al-Silicate Coating System Now Available That Can Eliminate Hazards of Carcinogenic Cr +6 in Al...OMB control number. 1. REPORT DATE NOV 2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Cr -Free Metallic

  3. Formation energy of vacancies in FeCr alloys: Dependence on Cr concentration

    Energy Technology Data Exchange (ETDEWEB)

    Rio, Emma del, E-mail: emma.delrio@upm.e [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain); Sampedro, Jesus M. [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain); Dogo, Harun [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, POB 1663, Los Alamos, NM (United States); Caturla, Maria J., E-mail: MJ.Caturla@ua.e [Dept. de Fisica Aplicada, Facultad de Ciencias, Fase II, Universidad de Alicante, Alicante E-03690 (Spain); Caro, Magdalena [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, POB 1663, Los Alamos, NM (United States); Caro, Alfredo, E-mail: caro@lanl.go [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, POB 1663, Los Alamos, NM (United States); Perlado, J. Manuel [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain)

    2011-01-01

    A modified version of the concentration-dependent model (CDM) potential (A. Caro et al., Phys. Rev. Lett. 95 (2005) 075702) has been developed to study defects in Fe-Cr for different Cr concentrations. A comparison between this new potential and DFT results for a variety of point defect configurations is performed in order to test its reliability for radiation damage studies. The effect of Cr concentration on the vacancy formation energy in Fe-Cr alloys is analyzed in detail. This study shows a linear dependence of the vacancy formation energy on Cr concentration for values above 6% of Cr. However, the formation energy deviates from the linear interpolation in the region below 6% Cr concentration. In order to understand this behavior, the influence of the relative positions between Cr atoms and vacant sites on the vacancy formation energy has been studied.

  4. Cr/alpha-Cr2O3 monodispersed spherical core-shell particles based solar absorbers

    CSIR Research Space (South Africa)

    Khamlich, S

    2011-07-01

    Full Text Available Monodispersed spherical core-shell particles of Cr/alpha-Cr2O3 cermet ACG coatings investigated within this contribution could be successfully employed in thermal converters. Their selectivity depends on their chemical, physical and structural...

  5. Microstructure and mechanical properties of thermal sprayed nanostructured Cr3C2-Ni20Cr coatings

    OpenAIRE

    Cecilio Alvares da Cunha; Nelson Batista de Lima; Jose Roberto Martinelli; Ana Helena de Almeida Bressiani; Armando Guilherme Fernando Padial; Lalgudi Venkataraman Ramanathan

    2008-01-01

    Cr3C2-Ni20Cr coatings have been used for corrosion and wear resistant applications. However, one of the shortcomings of these coatings is its low hardness, and consequent low wear resistance, for long term high temperature applications. Nanostructured coatings of many materials have exhibited higher hardness and strength compared with conventional coatings of the same material. Consequently, nanostructured coatings of other materials, including Cr3C2-Ni20Cr have been attempted to enhance over...

  6. Crónica (Chronicle

    Directory of Open Access Journals (Sweden)

    Rubén Darío

    2015-09-01

    Full Text Available En siete escasas páginas, Rubén Darío publicó esta interesante «Crónica», en el número 5 de marzo de 1892 de la Revista de Costa Rica. La dirigía el ilustre poeta costarricense, y amigo suyo, Justo A. Facio. Figura entre las páginas 317 y 323. A punto de cumplirse el centenario de la muerte del gran poeta hispanoamericano, en 2016, letras incluye este documento que su autor seguramente escribió en Costa Rica, durante su breve visita de aquel año. En varios de sus es- critos, Darío siempre expresó su afecto y simpatía por el país vecino de su patria natal; aquí forjó buenas amistades, y los historiadores de la literatura no tienen duda de que su presencia, física e intelectual, influyó mucho en el desarrollo de las letras costarricenses. Esta «crónica» bien puede tomarse como un verdadero cuadro de costumbres, modalidad que se cultivó con frecuencia y esmero en Centroamérica, en especial durante el último cuarto del siglo XIX. Darío era un joven escritor de veinticinco años, pero ya era dueño de una pluma diestra de un innegable talento que muy pronto se le reconocería en todo el Continente. Ya había publicado tres breves libros de poemas, incluido su célebre Azul... y estaba escribiendo y reuniendo las páginas que titularía, años después, Prosas profanas. Está por cumplirse un siglo desde la desaparición física del poeta centroamericano que tanto influyó en las letras hispanoamericanas y peninsulares, y que tanta bibliografía crítica ha producido. Como homenaje al centenario, letras contribuye con este pequeño hallazgo bibliográfico, un poco olvidado quizá, sobre un fragmento de la vida y la sociedad de finales del siglo XIX en Costa Rica. Sherry E. Gapper Directora

  7. Spin polarization effect for Cr2 molecule

    Institute of Scientific and Technical Information of China (English)

    Yan Shi-Ying

    2008-01-01

    Density functional theory (DFT) (B3P86) of Ganssian 03 has been used to optimize the structure of the Cr2 molecule, a transition metal element molecule. The result shows that the ground state for the Cr2 molecule is a 13-multiple state, indicating that there exists a spin polarization effect in the Cr2 molecule. Meanwhile, we have not found any spin pollution because the wave function of the ground state does not mingle with wave functions of higher-energy states. So the ground state for Cr2 molecule being a 13-multiple state is indicative of spin polarization effect of the Cr2 molecule among transition metal elements, that is, there are 12 parallel spin electrons in the Cr2 molecule. The number of non-conjugated electrons is greatest. These electrons occupy different spatial orbitals so that the energy of the Cr2 molecule is minimized. It can be concluded that the effect of parallel spin in the Cr2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition,the Murrell-Sorbie potential functions with the parameters for the ground state and other states of the Cr2 molecule are derived. The dissociation energy De for the ground state of the Cr2 molecule is 0.1034eV, equilibrium bond length Re is 0.3396nm, and vibration frequency ωe is 73.81cm-1. Its force constants f2, f3 and f4 are 0.0835, -0.2831 and 0.3535 aJ·nm-4 respectively. The other spectroscopic data for the ground state of the Cr2 molecule ωeχe, Be and αe are 1.2105, 0.0562 and 7.2938 × 10-4cm-1 respectively.

  8. Cr-Ni ALLOY ELECTRODEPOSITION AND COMPARISON WITH CONVENTIONAL PURE Cr COATING TECHNIQUE

    Directory of Open Access Journals (Sweden)

    M. Moniruzzaman

    2012-12-01

    Full Text Available Cr coating is widely used as the outer surface of precision parts due to its attractive appearance and superior corrosion resistance properties. It is obtained by electrodeposition via a conventional bath with hexavalent Cr ions. This manufacturing technique has many drawbacks, such as very low efficiency and high operating temperature and it is hazardous to health. In this work, we studied a Cr-Ni alloy deposition technique and compared the alloy coating properties to those with conventional Cr coating. Sequential two-step alloy electrodeposition was also compared. We took varying concentrations of Cr, Ni and complexing agents for the electrodeposition of Cr-Ni alloy and sequential Cr-Ni alloy coating on mild steel. Operating parameters, i.e. current density and temperature, were varied to examine their effects on the coating properties. The coatings thus obtained were characterized by visual observation, corrosion test, microhardness measurement, morphology and chemical analysis. The Cr-Ni alloy coating was found to be more corrosion resistant in 5% NaCl solution and harder than the pure Cr coating obtained by conventional electrodeposition. Toxic gas was produced in a much lower extent in the alloy coating than the conventional Cr coating technique. Again, the two-step Cr-Ni alloy coating was found better in terms of corrosion resistance as well as hardness compared to the Cr-Ni alloy coating. The process was also found to be much more environmentally friendly.

  9. Isotope Effects in the Bonds of beta-CrOOH and beta-CrOOD

    DEFF Research Database (Denmark)

    Nørlund Christensen, A.; Hansen, P.; Lehmann, M. S.

    1976-01-01

    Samples of orthorhombic chromium oxide hydroxide, beta -CrOOH, and the deuterated compound, beta -CrOOD, were prepared hydrothermally. The crystal structures were determined by powder profile refinement technique using neutron diffraction data. Unit cells are: beta -CrOOH: a equals 4. 862(2) A, b...

  10. Tissue accumulation and urinary excretion of Cr in chromium picolinate (CrPic)-supplemented lambs.

    Science.gov (United States)

    Dallago, Bruno Stéfano Lima; Lima, Bárbara Alcântara Ferreira; Braz, Shélida Vasconcelos; Mustafa, Vanessa da Silva; McManus, Concepta; Paim, Tiago do Prado; Campeche, Aline; Gomes, Edgard Franco; Louvandini, Helder

    2016-05-01

    Chromium (Cr) concentrations in liver, kidney, spleen, heart, lymph node, skeletal muscle, bone, testis and urine of lambs were measured to trace the biodistribution and bioaccumulation of Cr after oral supplementation with chromium picolinate (CrPic). Twenty-four Santa Inês lambs were treated with four different concentrations of CrPic: placebo, 0.250, 0.375 and 0.500 mg of CrPic/animal/day for 84 days. The basal diet consisted of Panicum maximum cv Massai hay and concentrate. Cr concentrations were measured by ICP-MS measuring (52)Cr as collected mass. There was a positive linear relationship between dose administered and the accumulation of Cr in the heart, lungs and testis. Urinary excretion of Cr occurred in a time and dose-dependent manner, so the longer or more dietary Cr provided, the greater excretion of the element. As some non-carcass components (such as lungs or heart) are added to bone and visceral meal to feed animals, there is a risk of bioaccumulation and biomagnification due to Cr offered as CrPic in the diet.

  11. Cr(VI) and Cr(III)-Based Conversion Coatings on Zinc

    NARCIS (Netherlands)

    Zhang, X.

    2005-01-01

    With the aims of understanding the protective mechanism of chromate conversion coatings and developing alternatives to chromate treatments, the physical natures and corrosion properties of Cr(VI) and Cr(III) treated zinc have been investigated in this work. The Cr(VI) treatments were carried out in

  12. Cr(VI) and Cr(III)-Based Conversion Coatings on Zinc

    NARCIS (Netherlands)

    Zhang, X.

    2005-01-01

    With the aims of understanding the protective mechanism of chromate conversion coatings and developing alternatives to chromate treatments, the physical natures and corrosion properties of Cr(VI) and Cr(III) treated zinc have been investigated in this work. The Cr(VI) treatments were carried out in

  13. Crónica (Chronicle)

    OpenAIRE

    2015-01-01

    En siete escasas páginas, Rubén Darío publicó esta interesante «Crónica», en el número 5 de marzo de 1892 de la Revista de Costa Rica. La dirigía el ilustre poeta costarricense, y amigo suyo, Justo A. Facio. Figura entre las páginas 317 y 323. A punto de cumplirse el centenario de la muerte del gran poeta hispanoamericano, en 2016, letras incluye este documento que su autor seguramente escribió en Costa Rica, durante su breve visita de aquel año. En varios de sus es- critos, Darío siempre exp...

  14. Crónicas urbanas

    Directory of Open Access Journals (Sweden)

    Oscar Garcia

    2012-12-01

    Full Text Available The urban chronicle is probably one of the least cultivated genres in Bolivia, not because the country lacks a repertoire of urban stories, but rather that those stories are neither produced nor consumed as a literary "genre". They are, instead, lived, savored and distributed through circuits of affection by which the city, the country and its inhabitants breathe their daily lives, the clamor forged by their stories of struggle, by their sorrows and disappointments. What follows is a sample of what these stories are capable of saying when caught by the sharp ear of an inveterate “paceño” who listens to the city, the country and the time lived by those in Bolivia.La crónica urbana es probablemente uno de los géneros menos cultivados en Bolivia, y no precisamente porque el país carezca de un repertorio de relatos urbanos, sino más bien porque esos relatos no son producidos ni consumidos como “género” literario. Son más bien vividos, saboreados y distribuidos a través de circuitos de afectividad por los que la ciudad, el país y sus habitantes revelan los ritmos de su cotidianidad, los “ruidos” que provocan sus historias de luchas, los sonidos que arrancan sus tristezas y desengaños. Lo que sigue es una muestra de lo que estos relatos pueden llegar a decir cuando los atrapa el oído crítico de un paceño empedernido que escucha la ciudad, el país y el tiempo que se vive en Bolivia.

  15. Bond strength of W-Cu/CuCr integrated material

    Institute of Scientific and Technical Information of China (English)

    范志康; 梁淑华; 薛旭

    2001-01-01

    The bond strength of W-Cu/CuCr integrated material was investigated. The results show that the fracture of W-Cu/CuCr integrated material often takes place at W-Cu/CuCr interface. Some alloying elements enhance the bond of W and CuCr alloy, which results in the increase of the strength of the W-Cu/CuCr interface. And the fracture of the WCu/CuCr integrated material occurs in the CuCr alloy part, not at the W-Cu/CuCr interface. Chromium in CuCr alloy part of the integrated material can improve Cr diffusing from the CuCr alloy to W-Cu composite and can be alloyed (near the W-Cu/CuCr interface) in the W-Cu composite. Thus the strength of W-Cu/CuCr interface is also increased.

  16. Common definition for categories of clinical research: a prerequisite for a survey on regulatory requirements by the European Clinical Research Infrastructures Network (ECRIN)

    DEFF Research Database (Denmark)

    Kubiak, Christine; de Andres-Trelles, Fernando; Kuchinke, Wolfgang

    2009-01-01

    BACKGROUND: Thorough knowledge of the regulatory requirements is a challenging prerequisite for conducting multinational clinical studies in Europe given their complexity and heterogeneity in regulation and perception across the EU member states. METHODS: In order to summarise the current situation...... with cell therapy, etc.); diagnostic studies; clinical research on nutrition; other interventional clinical research (including trials in complementary and alternative medicine, trials with collection of blood or tissue samples, physiology studies, etc.); and epidemiology studies. Our classification...

  17. Preliminary Microstructural and Microscratch Results of Ni-Cr-Fe and Cr3C2-NiCr Coatings on Magnesium Substrate

    Science.gov (United States)

    Istrate, B.; Munteanu, C.; Lupescu, S.; Benchea, M.; Vizureanu, P.

    2017-06-01

    Thermal coatings have a large scale application in aerospace and automotive field, as barriers improving wear mechanical characteristics and corrosion resistance. In present research, there have been used two types of coatings, Ni-Cr-Fe, respectively Cr3C2-NiCr which were deposited on magnesium based alloys (pure magnesium and Mg-30Y master alloy). There have been investigated the microstructural aspects through scanning electronic microscopy and XRD analysis and also a series of mechanical characteristics through microscratch and indentation determinations. The results revealed the formation of some adherent layers resistant to the penetration of the metallic indenter, the coatings did not suffer major damages. Microstructural analysis highlighted the formation of Cr3C2, Cr7C3, Cr3Ni2, Cr7Ni3, FeNi3, Cr-Ni phases. Also, the apparent coefficient of friction for Ni-Cr-Fe coatings presents superior values than Cr3C2-NiCr coatings.

  18. Homogeneous and Heterogeneous (Fex, Cr1-x)(OH)3 Precipitation: Implications for Cr Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Chong; Zuo, Xiaobing; Cao, B; Hu, Yandi

    2016-02-16

    The formation of (Fe, Cr)(OH)3 nanoparticles determines the fate of aqueous Cr in many aquatic environments. Using small angle X-ray scattering, precipitation rates of (Fe, Cr)(OH)3 nanoparticles in solution and on quartz were quantified from 0.1 mM Fe(III) solutions containing 0 – 0.25 mM Cr(III) at pH = 3.7 ± 0.2. Concentration ratio of aqueous Cr(III)/Fe(III) controlled the chemical composition (x) of (Fex, Cr1-x)(OH)3 precipitates, solutions’ supersaturation with respect to precipitates, and the surface charge of quartz. Therefore, aqueous Cr(III)/Fe(III) ratio affected homogeneous (in solution) and heterogeneous (on quartz) precipitation rates of (Fex, Cr1-x)(OH)3 through different mechanisms. The sequestration mechanisms of Cr(III) in precipitates were also investigated. In solutions with high aqueous Cr(III)/Fe(III) ratios, surface enrichment of Cr(III) on the precipitates occurred, resulting in slower particle growth in solution. From solutions with 0 – 0.1 mM Cr(III), the particles on quartz grew from 2 to 4 nm within 1 h. Interestingly, from solution with 0.25 mM Cr(III), particles of two distinct sizes (2 and 6 nm) formed on quartz, and their sizes remained unchanged throughout the reaction. Our study provided new insights on homogeneous and heterogeneous precipitation of (Fex, Cr1-x)(OH)3 nanoparticles, which can help determine the fate of Cr in aquatic environments.

  19. O crítico de Almanaque

    Directory of Open Access Journals (Sweden)

    Renata Praça de Souza Telles

    1997-12-01

    Full Text Available Almanaque — cadernos de literatura e ensaio publica, em 1977, "A crítica da 'razão' elitista", um ataque à crítica literária brasileira desferido por dois de seus membros — Lígia Chiappini Moraes Leite e Flávio Aguiar. Centrando-se na relação literatura/imprensa, elite/massa, o manifesto exclui posições e demarca fronteiras, inserindo-se na disputa em torno da definição do lugar e da função do crítico: o que é, o que fala, para quem, de onde? Partindo de algumas pistas encontradas no texto, tento mostrar aqui como se define e se localiza o crítico de Almanaque nessa polêmica que acompanha a crítica literária, brasileira no século XX.

  20. Biosorption of Cr(VI)_ and Cr(III)_Arthrobacter species

    CERN Document Server

    Gelagutashvili, E; Gurielidze, M

    2011-01-01

    The biosorption of Cr(VI)_ and Cr(III)_ Arthrobacter species (Arthrobacter globiformis and Arthrobacter oxidas) was studied simultaneous application dialysis and atomic absorption analysis. Also biosorption of Cr(VI) in the presence of Zn(II) during growth of Arthrobacter species and Cr(III) in the presence of Mn(II) were discussed. Comparative Cr(VI)_ and Cr(III)_ Arthrobacter species shown, that Cr(III) was more effectively adsorbed by both bacterium than Cr(VI). The adsorption capacity is the same for both the Chromium-Arthrobacter systems. The biosorption constants for Cr(III) is higher than for Cr(VI) 5.7-5.9- fold for both species. Comparative Freundlich biosorption characteristics Cr(VI) Arthrobacter species of living and dry cells shown, that capacity(n) is in both cases the same(1.25,1.35). Dry cells have larger biosorption constant for both species, than living cells. Biosorption characteristics (K) and (n) for A. oxidas are without Mn(II) and in the presence of Mn(II) 2.6 x 10-4 (K), 1.37 (n) and 2...

  1. Effect of Cr content on the corrosion performance of low-Cr alloy steel in a CO2 environment

    Science.gov (United States)

    Xu, Lining; Wang, Bei; Zhu, Jinyang; Li, Wei; Zheng, Ziyi

    2016-08-01

    Low-Cr alloy steel demonstrates lower corrosion rate than does C steel in a high-temperature and high-pressure CO2-containing environment. This study aimed to clarify the role of the Cr content in mitigating corrosion and reports the performance of 1%Cr, 2%Cr, 3%Cr, 4%Cr, 5%Cr, and 6.5%Cr steels. The results show that low-Cr alloy steel in CO2 at 80 °C and 0.8 MPa possesses spontaneous prepassivation characteristics when the Cr content is 3% or higher. Furthermore, the formation and peel-off of a prepassivation film on 3%Cr-6.5%Cr steels surfaces during polarization demonstrate that adequate amount of Cr in the steel substrate can cause protective layer. The main component of prepassivation film on 3%Cr steel is Cr(OH)3. Thus, the role of Cr is revealed. An adequate amount of Cr in the steel substrate causes the formation of protective Cr(OH)3 layer, which helps low-Cr steel to possess prepassivation characteristics. Prepassivation is the reason why low-Cr steel has a lower corrosion rate than C steel.

  2. Plantago lanceolata growth and Cr uptake after mycorrhizal inoculation in a Cr amended substrate

    Directory of Open Access Journals (Sweden)

    Amaia Nogales

    2012-03-01

    Full Text Available Arbuscular mycorrhizal fungi from two chromium contaminated sites, one with 275 mg kg-1 of Cr (zone A and the other with 550 mg kg-1 Cr (zone B, were multiplied and tentatively identified. The effect of both fungal consortia on Plantago lanceolata plant growth in a substrate amended with 200 mg kg-1 of Cr and with 400 mg kg-1 Cr was assessed and compared with the growth of plants inoculated with Glomus intraradices BEG72. Only the plants inoculated with G. intraradices BEG72 and with the fungal consortia obtained from the area with a high Cr contamination (zone B grew in the soil with 400 mg kg-1 of Cr. The consortia of fungi from zone B, decreased the plant’s uptake/translocation of the heavy metal compared with G. intraradices BEG72. These results underscore the differential effect of AM fungi in conferring bioprotection in Cr contaminated soils.

  3. enfoque crítico

    Directory of Open Access Journals (Sweden)

    Elkin Rubiano

    2005-01-01

    Full Text Available El autor del ensayo evalúa algunos de los supuestos teóricos que se han venido desarrollado en las ciencias sociales con respecto a las nuevas tecnologías de la información y la comunicación: por un lado, la consideración de que estas tecnologías se han convertido en el vehículo de una movilización política de dimensiones globales configurando un «ágora global», por el otro, el supuesto según el cual las nuevas tecnologías posibilitan la construcción de sujetos libres, autónomos y reflexivos. En este texto ambos supuestos se ponen en discusión con el apoyo de la «teoría crítica». Finalmente, el autor toma posición frente a los académicos que ven en las nuevas tecnologías posibilidades de emancipación haciendo un llamado por un tipo de análisis que los utopistas tecnológicos han dejado de lado: la economía política. Un tipo de análisis que se hace impostergable en la fase del capitalismo tardío.

  4. Crítica, sabotaje y subalternidad

    Directory of Open Access Journals (Sweden)

    Manuel Asensi Pérez

    2013-07-01

    Full Text Available Este ensayo define un “nuevo” concepto de crítica denominado “crítica como sabotaje”, su necesidad en el contexto de la posglobalización y sus puntos de referencia. Para ello, introduce una definición de la textualidad como fuerza performativa real que modeliza la visión del mundo de los receptores y les incita a llevar a cabo actos y discursos. Asimismo, ilustra la “crítica como sabotaje” mediante unos breves ejemplos pertenecientes a diferentes registros semióticos.

  5. Perpendicular magnetic anisotropy of Co85Cr15/Pt multilayers

    Institute of Scientific and Technical Information of China (English)

    Pol Hwang; Baohe Li; Tao Yang; Zhonghai Zhai; Fengwu Zhu

    2004-01-01

    The CoCr/Pt bilayers and (CoCr/Pt)20 multilayers with Pt underlayer were prepared by DC magnetron sputtering. The effects of prepared condition on perpendicular magnetic anisotropy were investigated. The results show that the thickness of Pt underlayer has a great effect on the microstructure and perpendicular magnetic anisotropy of CoCr/Pt bilayers and (CoCr/Pt)20 multilayers.When the thickness of Pt underlayer increases, Pt(111) and CoCr(002) peaks of both CoCr/Pt bilayers and (CoCr/Pt)20 multilayers increase and the bilayer periodicity of the multilayers is improved. The effective magnetic anisotropy of (CoCr/Pt)20 multilayers with Pt underlayer was much larger than that of CoCr/Pt bilayers. The (CoCr/Pt)20 multilayers has a stronger perpendicular magnetic anisotropy than that of CoCr/Pt bilayers. This is ascribed to the interface magnetic anisotropy of the multilayers.

  6. Half-magnetization plateaux in Cr spinels

    Energy Technology Data Exchange (ETDEWEB)

    Shannon, N [H. H. Wills Physics Lab, Tyndall Av., Bristol BS8 1TL (United Kingdom); Ueda, H [ISSP, University of Tokyo, Kashiwa, 277-8581 (Japan); Motome, Y [Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan); Penc, K [Research Institute for Solid State Physics and Optics, H-1525 Budapest, P.O.B. 49 (Hungary); Shiba, H [The Institute of Pure and Applied Physics, 2-31-22 Yushima, Bunkyo-ku, Tokyo 113-0034 (Japan); Takagi, H [Department of Advanced Materials Science, University of Tokyo, Kashiwa, 277-8651 (Japan)

    2006-11-15

    Magnetization plateaux, visible as anomalies in magnetic susceptibility at low temperatures, are one of the hallmarks of frustrated magnetism. An extremely robust halfmagnetization plateau is observed in the spinel oxides CdCr{sub 2}O{sub 4} and HgCr{sub 2}O{sub 4}, where it is accompanied by a substantial lattice distortion. We give an overview of the present state experiment for CdCr{sub 2}O{sub 4} and HgCr{sub 2}O{sub 4}, and show how such a half-magnetization plateau arises quite naturally in a simple model of these systems, once coupling to the lattice is taken into account.

  7. Photochromic lens mirror-coated with Cr

    Science.gov (United States)

    Shin, Sungho; Lee, Myeongkyu

    2007-11-01

    We have designed and fabricated mirror-coated photochromic lenses for use in sunglasses. These lenses consisted of a Cr thin film sandwiched between two SiO2 layers on the front surface and an anti-reflection (AR) coating on the backside. The SiO2 films above and below the Cr layer were introduced as the protection and buffer layers, respectively. The AR coating was to suppress back-reflection from the lens surface. Deposition of all coating layers were carried out by an e-beam evaporator under Ar atmosphere at P = 10-5 Torr and T = 70 °C. As expected, the overall transmittance decreased with increasing Cr thickness. For a Cr layer of 5 nm thickness, it changed from about 45% in the bleached state down to 25% after exposure to sunlight. This is consistent with the transmission range typically required for sunglasses.

  8. Cytotoxic and genotoxic potential of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA complex in human hepatoma (HepG2) cells.

    Science.gov (United States)

    Novotnik, Breda; Ščančar, Janez; Milačič, Radmila; Filipič, Metka; Žegura, Bojana

    2016-07-01

    Chromium (Cr) and ethylenediaminetetraacetate (EDTA) are common environmental pollutants and can be present in high concentrations in surface waters at the same time. Therefore, chelation of Cr with EDTA can occur and thereby stable Cr(III)-EDTA complex is formed. Since there are no literature data on Cr(III)-EDTA toxicity, the aim of our work was to evaluate and compare Cr(III)-EDTA cytotoxic and genotoxic activity with those of Cr(VI) and Cr(III)-nitrate in human hepatoma (HepG2) cell line. First the effect of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA on cell viability was studied in the concentration range from 0.04 μg mL(-1) to 25 μg mL(-1) after 24 h exposure. Further the influence of non-cytotoxic concentrations of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA on DNA damage and genomic stability was determined with the comet assay and cytokinesis block micronucleus cytome assay, respectively. Cell viability was decreased only by Cr(VI) at concentrations above 1.0 μg mL(-1). Cr(VI) at ≥0.2 μg mL(-1) and Cr(III) at ≥1.0 μg mL(-1) induced DNA damage, while after Cr(III)-EDTA exposure no formation DNA strand breaks was determined. Statistically significant formation of micronuclei was induced only by Cr(VI) at ≥0.2 μg mL(-1), while no influence on the frequency of nuclear buds nor nucleoplasmic bridges was observed at any exposure. This study provides the first evidence that Cr(III)-EDTA did not induce DNA damage and had no influence on the genomic stability of HepG2 cells.

  9. Development of a scale for the evaluation of patients' rights prerequisites at educational hospitals in Iran: a study using the Delphi technique.

    Science.gov (United States)

    Aazami, Sanaz; Mozafari, Mosayeb

    2015-01-01

    The patients' rights status is one of the essential elements in defining norms related to the concept of clinical governance system. In addition, the patients' rights status is an important index for quality of care offered in the health care system. However, the lack of a coherent instrument makes it difficult to evaluate patients' rights status in hospitals and clinics. The aim of this study was to develop an instrument for the evaluation of patients' rights prerequisites at educational hospitals in Iran. This study was conducted using the modified Delphi technique. In this study, 36 experts in the fields of law, medicine, and professional ethics were participated. The panel of experts participated in 3 rounds. First, experts were asked to judge some pre-identified items, and then, excluded items were judged again in the second round. At the end of the third round, all of the agreed items were included in the final list to form an evaluative scale on practice of patients' rights. Experts were asked to judge a total 171 items in 3 rounds. Around 31% (n = 53) of items obtained the panel's approval to be included in the final version of the scale. The experts' opinions were collected using face-to-face interviews and electronic email during a 6-month period of data collection from October 2013 to February 2014. This study developed a 53-item scale for evaluation of patients' rights prerequisites in educational hospitals in Iran. This scale was developed in 7 areas of commitments including university education, research, supervision, process management, physical structure, organizational policy, and human resources management. This study developed an evaluative scale to assess the practice of patients' rights in educational hospitals. The items in the final version of this scale were obtained from a consensus of experts and the instrument can be used to evaluate the context and prerequisites for practice of patients' rights in Iranian educational hospitals.

  10. Flatness of CR submanifolds in a sphere

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In Euclidean geometry, for a real submanifold M in E n+a , M is a piece of E n if and only if its second fundamental form is identically zero. In projective geometry, for a complex submanifold M in CP n+a , M is a piece of CP n if and only if its projective second fundamental form is identically zero. In CR geometry, we prove the CR analogue of this fact in this paper.

  11. El costo del crédito

    OpenAIRE

    Soto Chavez, Robert

    2006-01-01

    ¿Es elevado el costo del crédito del Perú?. La respuesta dependerá del segmento en el que se encuentre el cliente, escenario que ha sido originado por una elevada dispersión de las tasas de interés en nuestro país. El trabajo "El costo del crédito en el Perú" evalúa este escenario.

  12. Cr-Ni ALLOY ELECTRODEPOSITION AND COMPARISON WITH CONVENTIONAL PURE Cr COATING TECHNIQUE

    OpenAIRE

    Moniruzzaman, M; M.M. Rakib; F.T. Matin

    2012-01-01

    Cr coating is widely used as the outer surface of precision parts due to its attractive appearance and superior corrosion resistance properties. It is obtained by electrodeposition via a conventional bath with hexavalent Cr ions. This manufacturing technique has many drawbacks, such as very low efficiency and high operating temperature and it is hazardous to health. In this work, we studied a Cr-Ni alloy deposition technique and compared the alloy coating properties to those with conventional...

  13. Interatomic potential to study the formation of NiCr clusters in high Cr ferritic steels

    Science.gov (United States)

    Bonny, G.; Bakaev, A.; Olsson, P.; Domain, C.; Zhurkin, E. E.; Posselt, M.

    2017-02-01

    Under irradiation NiSiPCr clusters are formed in high-Cr ferritic martensitic steels as well as in FeCr model alloys. In the literature little is known about the origin and contribution to the hardening of these clusters. In this work we performed density functional theory (DFT) calculations to study the stability of small substitutional NiCr-vacancy clusters and interstitial configurations in bcc Fe. Based on DFT data and experimental considerations a ternary potential for the ferritic FeNiCr system was developed. The potential was applied to study the thermodynamic stability of NiCr clusters by means of Metropolis Monte Carlo (MMC) simulations. The results of our simulations show that Cr and Ni precipitate as separate fractions and suggest only a limited synergetic effect between Ni and Cr. Therefore our results suggest that the NiCrSiP clusters observed in experiments must be the result of other mechanisms than the synergy of Cr and Ni at thermal equilibrium.

  14. Creatine transporter (CrT; Slc6a8 knockout mice as a model of human CrT deficiency.

    Directory of Open Access Journals (Sweden)

    Matthew R Skelton

    Full Text Available Mutations in the creatine (Cr transporter (CrT; Slc6a8 gene lead to absence of brain Cr and intellectual disabilities, loss of speech, and behavioral abnormalities. To date, no mouse model of CrT deficiency exists in which to understand and develop treatments for this condition. The purpose of this study was to generate a mouse model of human CrT deficiency. We created mice with exons 2-4 of Slc6a8 flanked by loxP sites and crossed these to Cre:CMV mice to create a line of ubiquitous CrT knockout expressing mice. Mice were tested for learning and memory deficits and assayed for Cr and neurotransmitter levels. Male CrT(⁻/y (affected mice lack Cr in the brain and muscle with significant reductions of Cr in other tissues including heart and testes. CrT(⁻/y mice showed increased path length during acquisition and reversal learning in the Morris water maze. During probe trials, CrT(⁻/y mice showed increased average distance from the platform site. CrT(⁻/y mice showed reduced novel object recognition and conditioned fear memory compared to CrT(+/y. CrT(⁻/y mice had increased serotonin and 5-hydroxyindole acetic acid in the hippocampus and prefrontal cortex. Ubiquitous CrT knockout mice have learning and memory deficits resembling human CrT deficiency and this model should be useful in understanding this disorder.

  15. Reduction of Cr(VI) to Cr(III) by wetland plants: Potential for in situ heavy metal detoxification

    Energy Technology Data Exchange (ETDEWEB)

    Lytle, C.M.; Qian, J.H.; Hansen, D.; Zayed, A.; Terry, N. [Univ. of California, Berkeley, CA (United States). Dept. of Plant and Microbial Biology; Lytle, F.W. [The EXAFS Co., Pioche, NV (United States); Yang, N. [Sandia National Labs., Livermore, CA (United States)

    1998-10-15

    Reduction of heavy metals in situ by plants may be a useful detoxification mechanism for phytoremediation. Using X-ray spectroscopy, the authors show that Eichhornia crassipes (water hyacinth), supplied with Cr(VI) in nutrient culture, accumulated nontoxic Cr(III) in root and shoot tissues. The reduction of Cr(VI) to Cr(III) appeared to occur in the fine lateral roots. The Cr(III) was subsequently translocated to leaf tissues. Extended X-ray absorption fine structure of Cr in leaf and petiole differed when compared to Cr in roots. In roots, Cr(III) was hydrated by water, but in petiole and more so in leaf, a portion of the Cr(III) may be bound to oxalate ligands. This suggests that E. crassipes detoxified Cr(VI) upon root uptake and transported a portion of the detoxified Cr to leaf tissues. Cr-rich crystalline structures were observed on the leaf surface. The chemical species of Cr in other plants, collected from wetlands that contained Cr(VI)-contaminated wastewater, was also found to be Cr(III). The authors propose that this plant-based reduction of Cr(VI) by E. crassipes has the potential to be used for the in situ detoxification of Cr(VI)-contaminated wastestreams.

  16. Novel reduction of Cr(VI) from wastewater using a naturally derived microcapsule loaded with rutin-Cr(III) complex.

    Science.gov (United States)

    Qi, Yun; Jiang, Meng; Cui, Yuan-Lu; Zhao, Lin; Liu, Shejiang

    2015-03-21

    The harmfulness of carcinogenic hexavalent chromium (Cr(VI)) is dramatically decreased when Cr(VI) is reduced to trivalent chromium (Cr(III)). Rutin, a natural flavonoid, exhibits excellent antioxidant activity by coordinating metal ions. In this study, a complex containing rutin and Cr(III) (rutin-Cr(III)) was synthesized and characterized. The rutin-Cr(III) complex was much easier to reduce than rutin. The reduction of the rutin-Cr(III) complex was highly pH-dependent, with 90% of the Cr(VI) being reduced to Cr(III) in 2h under optimal conditions. A biodegradable, sustained-release system encapsulating the rutin-Cr(III) complex in a alginate-chitosan microcapsule (rutin-Cr(III) ACMS) was also evaluated, and the reduction of Cr(VI) was assessed. This study also demonstrated that low-pH solutions increased the reduction rate of Cr(VI). The environmentally friendly microcapsules can reduce Cr(VI) for prolonged periods of time and can easily biodegrade after releasing the rutin-Cr(III) complex. Given the excellent performance of rutin-Cr(III) ACMS, the microcapsule system represents an effective system for the remediation of Cr(VI) pollution.

  17. Correlation between bulk- and surface chemistry of Cr-tanned leather and the release of Cr(III) and Cr(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Hedberg, Yolanda S., E-mail: yolanda@kth.se [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, SE-10044 Stockholm (Sweden); Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-17177 Stockholm (Sweden); Lidén, Carola, E-mail: carola.liden@ki.se [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-17177 Stockholm (Sweden); Odnevall Wallinder, Inger, E-mail: ingero@kth.se [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, SE-10044 Stockholm (Sweden)

    2014-09-15

    Graphical abstract: - Highlights: • Released reducing/complexing leather-specific species can reduce released Cr(VI). • No co-released species enable the formation of Cr(VI) in solution. • The major Cr species released from leather in phosphate buffer was Cr(III) (>82%). • No Cr(VI) was released into artificial sweat. - Abstract: About 1–3% of the adult general population in Europe is allergic to chromium (Cr). The assessment of the potential release of Cr(III) and Cr(VI) from leather is hence important from a human health and environmental risk perspective. The Cr(VI) content in leather was recently restricted in the European Union. The aim of this study was to assess possible correlations between the bulk and surface chemistry of leather, released Cr(III) and Cr(VI), and capacities of co-released leather specific species to reduce and complex released Cr. Four differently tanned leathers were characterized by scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and the diphenylcarbazide colorimetric method. Their characteristics were compared with results on Cr(III) and Cr(VI) release into artificial sweat (ASW, pH < 6.5) and phosphate buffer (PB, pH 7.5–8.0), measured by means of spectrophotometry and atomic absorption spectroscopy. Co-released leather-specific species were shown to reduce Cr(VI), both in ASW and in PB. Their reduction capacities correlated with findings of the surface content of Cr and of released Cr. Leather samples without this capacity, and with less aromatic surface groups visible by ATR-FTIR, revealed Cr(VI) both at the surface and in solution (PB)

  18. Effect of Cr content on mechanical and electrical properties of Ni-Cr thin films

    Energy Technology Data Exchange (ETDEWEB)

    Danisman, M., E-mail: muratdan@gmail.co [Yildiz Technical University, Faculty of Chemistry-Metallurgy, Metallurgical and Materials Engineering Department, Esenler 34220, Istanbul (Turkey); Cansever, N. [Yildiz Technical University, Faculty of Chemistry-Metallurgy, Metallurgical and Materials Engineering Department, Esenler 34220, Istanbul (Turkey)

    2010-03-18

    NiCr has been a popular choice for strain gage and electrical resistance application in various fields of engineering and science. Therefore, the phases at this binary system have been thoroughly investigated in the last decade. For Ni-Cr thin film production, sputtering from alloy targets is mostly discussed as a deposition method. However, Cr content in Ni-Cr alloy has major influence on different properties of the NiCr thin films. In order to investigate the effect of Cr content in Ni-Cr system, Ni over Cr thin films with a total thickness of 500 nm was deposited on glass substrates with different Cr/Ni thickness ratios as 0.1, 0.25 and 0.6. After deposition, thin films were annealed at 600 {sup o}C for 180 s in a Rapid Thermal Process (RTP) system to investigate the effect of different Cr contents on phase formation. The phase formations and lattice parameters were analyzed with low glancing angle X-ray Diffraction (XRD) and the Cr content in the thermally treated thin films was calculated with Energy Dispersive Spectrometry (EDS). Also, film composition along depth was also calculated by EDS analysis from the cross-section view of the annealed samples. Field Emission Scanning Electron Microscope (FESEM) images were taken from the cross-section view of the samples in order to observe the final film thicknesses and structures. Sheet resistance of each sample was measured with linear four point probe technique and resistivity of each phase was calculated. Furthermore, nanohardness and Young's Modulus of each sample was calculated by using nanoindentation method.

  19. Education and training as prerequisites for overcoming the difficulties in the implementation of ethical and legal norms concerning gender equality in a social environment

    Directory of Open Access Journals (Sweden)

    Gavrilović Danijela

    2008-01-01

    Full Text Available In this paper, the author advances the thesis that in today's Serbia there is no social consensus concerning the unequal treatment of men and women, and that 'patriarchal syndrome', stereotypes and prejudices are still widely present and are greatly influencing the functioning of social mechanisms and the achievement of gender equality. In Serbia the process of achieving the equal treatment of women de jure is still in progress. With the absence of consensus, which is a prerequisite for 'transmitting' social values encompassed by gender equality, the chances are little that equality will be attained de facto. This paper is meant as a warning that not all types of women's inequality are easily noticeable, as well as that on the social scene there are many different and intertwined social actors which influence dealing with the problem of inequality, implementation of international and domestic legal acts, ethical standards, and taking steps to introduce mechanisms for achieving women's equality in society. One of the prerequisites for overcoming these difficulties is a system of education and educational resources, which promote the idea of gender equality.

  20. Thermodynamic Assessment of the La-Cr-O System

    DEFF Research Database (Denmark)

    Povoden, E.; Chen, Ming; Grundy, A.N.

    2009-01-01

    The La-Cr and the La-Cr-O systems are assessed using the Calphad approach. The calculated La-Cr phase diagram as well as LaO1.5-CrO1.5 phase diagrams in pure oxygen, air, and under reducing conditions are presented. Phase equilibria of the La-Cr-O system are calculated at 1273 K as a function...... of oxygen partial pressure. In the La-Cr system reported solubility of lanthanum in bcc chromium is considered in the modeling. In the La-Cr-O system the Gibbs energy functions of La2CrO6, La-2(CrO4)(3), and perovskite-structured LaCrO3 are presented, and oxygen solubilities in bcc and fcc metals...

  1. Correlation between bulk- and surface chemistry of Cr-tanned leather and the release of Cr(III) and Cr(VI).

    Science.gov (United States)

    Hedberg, Yolanda S; Lidén, Carola; Odnevall Wallinder, Inger

    2014-09-15

    About 1-3% of the adult general population in Europe is allergic to chromium (Cr). The assessment of the potential release of Cr(III) and Cr(VI) from leather is hence important from a human health and environmental risk perspective. The Cr(VI) content in leather was recently restricted in the European Union. The aim of this study was to assess possible correlations between the bulk and surface chemistry of leather, released Cr(III) and Cr(VI), and capacities of co-released leather specific species to reduce and complex released Cr. Four differently tanned leathers were characterized by scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and the diphenylcarbazide colorimetric method. Their characteristics were compared with results on Cr(III) and Cr(VI) release into artificial sweat (ASW, pHleather-specific species were shown to reduce Cr(VI), both in ASW and in PB. Their reduction capacities correlated with findings of the surface content of Cr and of released Cr. Leather samples without this capacity, and with less aromatic surface groups visible by ATR-FTIR, revealed Cr(VI) both at the surface and in solution (PB).

  2. Air Force Successes and Challenges in Cr(VI) Elimination

    Science.gov (United States)

    2011-05-10

    Cr(VI) has been used for 40+ years and is an excellent corrosion inhibitor • Cr(VI) compounds are highly toxic • National & International...use of Cr(VI) • Suitable Substitutes for Specific Applications are being Actively Sought 3 Chrome Reduction Plan Description: • Reduce Cr(VI) and...ion vapor deposited Al, and Cd coatings 2. Use trivalent chromium [Cr(III)] conversion coating (CC) on Dipsol IZ- C17+ zinc- nickel (Zn-Ni) coating

  3. Thermodynamic Assessment of the La-Cr-O System

    DEFF Research Database (Denmark)

    Povoden, E.; Chen, Ming; Grundy, A.N.

    2009-01-01

    The La-Cr and the La-Cr-O systems are assessed using the Calphad approach. The calculated La-Cr phase diagram as well as LaO1.5-CrO1.5 phase diagrams in pure oxygen, air, and under reducing conditions are presented. Phase equilibria of the La-Cr-O system are calculated at 1273 K as a function of ...

  4. Behaviour of Z phase in 9–12%Cr steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John

    2006-01-01

    –12%), Z phase precipitates much faster than in 9%Cr steels. Precipitation of Z phase is associated with dissolution of MX carbonitrides, and causes a breakdown in long term creep strength in 9–12%Cr steels. High Cr steels show creep instabilities accompanied with Z phase precipitation, whereas low Cr......–1250uC solution temperature of the unmodified CrNbN Z phase. Above the solution temperature the modified Z phase is replaced by MX particles....

  5. Cr(VI) formation during ozonation of Cr-containing materials in ...

    African Journals Online (AJOL)

    2011-10-14

    Oct 14, 2011 ... iron particles can reduce Cr(VI) to Cr(III) in aqueous medium. Pulverising time ... incorporating a Bruker AXS XFlash® 5010 Detector x-ray. EDS system ... determined with UV-visible spectrophotometry as described by McElroy ...

  6. Electrochemical behavior of Co-Cr and Ni-Cr dental cast alloys

    Institute of Scientific and Technical Information of China (English)

    Viswanathan S. SAJI; Han-Cheol CHOE

    2009-01-01

    The cast structures influencing the electrochemical corrosion behavior of Co-Cr and Ni-Cr dental alloys were studied using potentiodynamic polarization and AC impedance in 0.9% (mass fraction) NaCl solution at (37±1) ℃. The phase and microstructure of the alloys that were fabricated using two different casting methods viz. centrifugal casting and high frequency induction casting, were examined using X-ray diffraction analysis, scanning electron microscopy and energy dispersive spectroscopy. The roles of alloying elements and the passive film homogeneity on the corrosion resistance of Co-Cr-Mo and Ni-Cr-Mo dental cast alloys were reviewed. The results of electrochemical study show that the dependence of corrosion resistance on the microstructure associated with the casting methods is marginal. The Co-Cr alloy exhibits more desirable corrosion resistance properties than the Ni-Cr alloy. There is severe preferential dissolution of Ni-rich, Cr and Mo depleted zones in the Ni-Cr alloy.

  7. Calibration of CR-39 with monoenergetic protons

    Science.gov (United States)

    Xiaojiao, Duan; Xiaofei, Lan; Zhixin, Tan; Yongsheng, Huang; Shilun, Guo; Dawei, Yang; Naiyan, Wang

    2009-10-01

    Calibration of solid state nuclear track detector CR-39 was carried out with very low-energy monoenergetic protons of 20-100 keV from a Cockcroft Walton accelerator. To reduce the beam of the proton from the accelerator, a novel method was adopted by means of a high voltage pulse generator. The irradiation time of the proton beam on each CR-39 sheet was shortened to one pulse with duration of 100 ns, so that very separated proton tracks around 104 cm-2 can be irradiated and observed and measured on the surface of the CR-39 detector after etching. The variations of track diameter with etching time as well as with proton energy response curve has been carefully calibrated for the first time in this very low energy region. The calibration shows that the optical limit for the observation of etched tracks of protons in CR-39 is about or a little lower that 20 keV, above which the proton tracks can be seen clearly and the response curve can be used to distinguish protons from the other ions and determine the energy of the protons. The extension of response curve of protons from traditionally 20 to 100 keV in CR-39 is significant in retrieving information of protons produced in the studies of nuclear physics, plasma physics, ultrahigh intensity laser physics and laser acceleration.

  8. Explosive compaction of CuCr alloys

    Institute of Scientific and Technical Information of China (English)

    李金平; 罗守靖; 龚朝晖; 牛玮; 纪松

    2002-01-01

    The production of CuCr alloys utilizing explosive compaction was studied. Mixture powders of CuCr alloys placed in tubes with a dimension of d14.0mm×21.4mm can be compacted using explosive pads of 16.5mm or 22.5mm. Thicker pads of explosive make the compacts more porous. The effects of the ratio of me/mp, ratio of me/(mp+mt) and impact energy on the density of compacts were similar, they were chosen to control explosive compaction, respectively. When adequate value of the parameters me/mp, me/(mt+mp) and impact energy of unit area of tube was chosen, high density(7.858g/cm3), high hardness(HB189) and low conductance (13.6MS/m) of CuCr alloys could be made by explosive compaction. The general properties of CuCr alloys by explosive compaction are similar to those of CuCr alloys by traditional process.

  9. Magnetic Properties of Cr-based Ternary Compound CrAlGe

    Science.gov (United States)

    Yoshinaga, Soshi; Mitsui, Yoshifuru; Umetsu, Rie Y.; Koyama, Keiichi

    Structural and magnetic properties of Cr-based compound CrAlGe were investigated. The crystal structure was found to be an orthorhombic TiSi2-type with lattice parameters a = 0.4770 nm, b = 0.8254 nm and c = 0.8725 nm at room temperature. Magnetization curve of CrAlGe showed the ferromagnetic behavior. The saturation magnetic moment, spontaneous magnetic moment and Curie temperature of CrAlGe were determined to be 0.45 μB/f.u., 0.41 μB/f.u. and TC = 80 K, respectively. For the temperature T below 30 K, the decrease in the square of the spontaneous magnetization M0(T)2 was proportional to T2. However, for 30 CrAlGe is a weak itinerant electron ferromagnet.

  10. Contacts de créoles, créoles en contact

    OpenAIRE

    Goury, Laurence; Léglise, Isabelle

    2005-01-01

    International audience; Face à la diversité d'approches et au foisonnement de travaux dans le domaine du contact de langues, l'étude des créoles en contact avec d'autres langues – créoles ou non – semble quelque peu en retrait, se cantonnant essentiellement à l'étude de leur genèse. Ce numéro de revue tente de remédier à la faible présence de travaux sur les contacts entre langues créoles d'une part (d'où le titre : contacts de créoles) et entre des langues créoles et diverses langues dans le...

  11. Chromium sorption and Cr(VI) reduction to Cr(III) by grape stalks and yohimbe bark.

    Science.gov (United States)

    Fiol, Núria; Escudero, Carlos; Villaescusa, Isabel

    2008-07-01

    In this work, two low cost sorbents, grape stalks and yohimbe bark wastes were used to remove Cr(VI) and Cr(III) from aqueous solutions. Batch experiments were designed to obtain Cr(VI) and Cr(III) sorption data. The mechanism of Cr(III) and Cr(VI) removal and Cr(VI) reduction to Cr(III) by the two vegetable wastes, has been investigated. Fourier transform infrared rays (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis on solid phase were performed to determine the main functional groups that might be involved in metal uptake and to confirm the presence of Cr(III) on the sorbent, respectively. Results put into evidence that both sorbents are able to reduce Cr(VI) to its trivalent form.

  12. Electronic structure and magnetic ordering of the semiconducting chromium trihalides CrCl3, CrBr3, and CrI3

    KAUST Repository

    Wang, Hao

    2011-03-01

    We present results from an electronic structure investigation of the chromium halides CrCl3, CrBr3, and CrI3, as obtained by the linearized augmented plane wave method of density functional theory. Our interest focuses on the chloride. While all three halides display strong ferromagnetic coupling within the halide-Cr-halide triple layers, our emphasis is on differences in the interlayer magnetic coupling. In agreement with experimental results, our calculations indicate ferromagnetic ordering for CrBr3 as well as CrI3. The antiferromagnetic state of CrCl3 can be reproduced by introducing an on-site electron-electron repulsion. However, we observe that the ground state depends critically on the specific approach used. Our results show that a low temperature structural phase transition from monoclinic to trigonal is energetically favourable for CrCl3. © 2011 IOP Publishing Ltd.

  13. Electronic structure and magnetic ordering of the semiconducting chromium trihalides CrCl{sub 3}, CrBr{sub 3}, and CrI{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H; Schwingenschloegl, U [PSE Division, KAUST, Thuwal 23955-6900 (Saudi Arabia); Eyert, V, E-mail: udo.schwingenschlogl@kaust.edu.sa [Centre for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg (Germany)

    2011-03-23

    We present results from an electronic structure investigation of the chromium halides CrCl{sub 3}, CrBr{sub 3}, and CrI{sub 3}, as obtained by the linearized augmented plane wave method of density functional theory. Our interest focuses on the chloride. While all three halides display strong ferromagnetic coupling within the halide-Cr-halide triple layers, our emphasis is on differences in the interlayer magnetic coupling. In agreement with experimental results, our calculations indicate ferromagnetic ordering for CrBr{sub 3} as well as CrI{sub 3}. The antiferromagnetic state of CrCl{sub 3} can be reproduced by introducing an on-site electron-electron repulsion. However, we observe that the ground state depends critically on the specific approach used. Our results show that a low temperature structural phase transition from monoclinic to trigonal is energetically favourable for CrCl{sub 3}.

  14. Analysis of PTA hardfacing with CoCrWC and CoCrMoSi alloys

    Directory of Open Access Journals (Sweden)

    Adriano Scheid

    2013-12-01

    Full Text Available CoCrWC alloys are widely used to protect components that operate under wear and high temperature environments. Enhanced performance has been achieved with the CoCrMoSi alloys but processing this alloy system is still a challenge due to the presence of the brittle Laves phase, particularly when welding is involved. This work evaluated Plasma Transferred Arc coatings processed with the Co-based alloy CoMoCrSi - Tribaloy T400, reinforced with Laves phase, comparing its weldability to the CoCrWC - Stellite 6, reinforced with carbides. Coatings were also analyzed regarding the response to temperature exposure at 600°C for 7 days and subsequent effect on microstructure and sliding abrasive wear. Coatings characterization was carried out by light and scanning electron microscopy, X-ray diffraction and Vickers hardness. CoCrWC coatings exhibited a Cobalt solid solution dendritic microstructure and a thin interdendritic region with eutectic carbides, while CoCrMoSi deposits exhibit a large lamellar eutectic region of Laves phase and Cobalt solid solution and a small fraction of primary Laves phase. Although phase stability was observed by X-ray diffraction, coarsening of the microstructure occurred for both alloys. CoCrMoSi showed thicker lamellar Laves phase and CoCrWC coarser eutectic carbides. Coatings stability assessed by wear tests revealed that although the wear rate of the as-deposited CoCrMoSi alloy was lower than that of CoCrWC alloy its increase after temperature exposure was more significant, 22% against 15%. Results were discussed regarding the protection of industrial components in particular, bearings in 55AlZn hot dip galvanizing components.

  15. LaCrO{sub 3}-dispersed Cr for metallic interconnect of planar SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Song, Rak-Hyun; Shin, Dong Ryul [Korea Institute of Energy Research, Taejon (Korea, Republic of); Dokiya, Masayuki [National Institute of Materials and Chemical Research, Ibaraki (Japan)

    1996-12-31

    In the planar SOFC, the interconnect materials plays two roles as an electrical connection and as a gas separation plate in a cell stack. The interconnect materials must be chemically stable in reducing and oxidizing environments, and have high electronic conductivity, high thermal conductivity, matching thermal expansion with an electrolyte, high mechanical strength, good fabricability, and gas tightness. Lanthanum chromite so far has been mainly used as interconnect materials in planar SOFC. However, the ceramic materials are very weak in mechanical strength and have poor machining property as compared with metal. Also the metallic materials have high electronic conductivity and high thermal conductivity. Recently some researchers have studied metallic interconnects such as Al{sub 2}O{sub 3}/Inconel 600 cermet, Ni-20Cr coated with (LaSr)CoO{sub 3}, and Y{sub 2}O{sub 3-} or La{sub 2}O{sub 3}-dispersed Cr alloy. These alloys have still some problems because Ni-based alloys have high thermal expansion, the added Al{sub 2}O{sub 3}, Y{sub 2}O{sub 3} and La{sub 2}O{sub 3} to metals have no electronic conductivity, and the oxide formed on the surface of Cr alloy has high volatility. To solve these problems, in this study, LaCrO{sub 3}-dispersed Cr for metallic interconnect of planar SOFC was investigated. The LaCrO{sub 3}-dispersed Cr can be one candidate of metallic interconnect because LaCrO{sub 3} possesses electronic conductivity and Cr metal has relatively low thermal expansion. The content of 25 vol.% LaCrO{sub 3} Was selected on the basis of a theoretically calculated thermal expansion. The thermal expansion, electrical and oxidation properties were examined and the results were discussed as related to SOFC requirements.

  16. Bioremediation of chromium by the yeast Pichia guilliermondii: toxicity and accumulation of Cr (III) and Cr (VI) and the influence of riboflavin on Cr tolerance.

    Science.gov (United States)

    Ksheminska, Helena; Jaglarz, Anita; Fedorovych, Daria; Babyak, Lyubov; Yanovych, Dmytro; Kaszycki, Pawel; Koloczek, Henryk

    2003-01-01

    A comparative study has been made on the sensitivity of the yeast Pichia guilliermondii to Cr (III) and Cr (VI) as well as on the Cr uptake potential at growth-inhibitory concentrations of chromium. The strains used in the study were either isolated from natural sources or obtained from a laboratory strain collection. The results show that most of the natural strains were more tolerant to chromium and were able to grow in the presence of 5 mM Cr (III) or 0.5 mM Cr (VI), that is at concentrations which substantially inhibited the growth of laboratory strains. The cellular Cr content after treatment was similar for both strain types and ranged from 1.2-4.0 mg/g d.w. and 0.4-0.9 mg/g d.w., for Cr (III) and Cr (VI) forms, respectively, however, in one case of a natural strain it reached the value of 10 mg Cr (III)/g dry mass. Natural-source strains were grouped into four groups based on the yeasts' differential response to Cr (III) and Cr (VI). Hexavalent Cr-resistant mutants of a P. giuilliermondii laboratory strain, which revealed markedly changed capabilities of chromium accumulation, were obtained by means of UV-induced mutagenesis. Cr (VI) treatment triggered oversynthesis of riboflavin and the addition of exogenous riboflavin increased P. guilliermondii resistance to both Cr (III) and Cr (VI). Electrophoretic protein profiles revealed the induction and/or suppression of several proteins in response to toxic Cr (VI) levels.

  17. Wilde, la nueva crítica

    Directory of Open Access Journals (Sweden)

    Roxana Haydée Páez

    2002-11-01

    cultivados e ilustres de América Latina, recordando la más actual de Silvia Molloy que hace hincapié en el carácter político de una pose que fue rebajada tradicionalmente a la frivolidad, el artículo rescata la sutileza crítica del escritor. Encubiertas bajo un título que aparenta banalidad, La importancia de no hacer nada (1891, se encuentran las formulaciones teóricas de “El crítico como artista” y “Del crítico y del criticismo”. Anticipaciones inmersas en la pretendida vuelta decadentista al pasado, los preceptos sabiamente dosificados por el artista inclasificable, no sólo fueron musitados para repensar el tema del gusto, en el famoso ensayo de Susan Sontag, sino que tocaron desde el pasado, precisamente, a escrituras criticas como la de Ian Mukarovsky y Roland Barthe

  18. CR-V绥中海滩游

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    CR-V绥中海滩游:刚刚经历了北京少有的“大雾尊漫、雷声滚滚、暴雨倾盆的罕见天气,2005年8月13日(星期六)一大早,东风本田汽车鑫伯龙特约销售服务店内就异常热闹。近30辆东风本田CR-V汽车,共60余位车主齐聚鑫伯龙,“8月盛夏激情,相约海滨,共沐海风”CR-V车友联谊活动就此正式拉开了大旗。

  19. Understanding CrRLK1L Function

    DEFF Research Database (Denmark)

    Nissen, Karen Stoltenberg; Willats, William George Tycho; Malinovsky, Frederikke Gro

    2016-01-01

    To develop successfully in an ever-changing environment, it is essential for plants to monitor and control their growth. Therefore, cell expansion is carefully regulated to establish correct cell shape and size. In this review, we explore the role of the Catharanthus roseus receptor-like kinase (Cr......RLK1L) subfamily as regulators of cell expansion. Recently, the downstream signalling events of individual CrRLK1L pathways were discovered, implicating known modulators of cell expansion, such as reactive oxygen species (ROS) production, Ca(2+) dynamics, and exocytosis of cell wall material. Based...... on these intriguing new insights, we propose a model for a common pathway of CrRLK1L signalling that enables spatial and temporal control of cell wall extensibility throughout the plant....

  20. con enfermedades crónicas

    Directory of Open Access Journals (Sweden)

    Stefano Vinaccia

    2005-01-01

    Full Text Available El objetivo de la siguiente revisión teórica fue estudiar el impacto de las variables psicosociales sobre la calidad de vida de personas con enfermedades crónicas. Se plantea el concepto de salud como un comportamiento asociado al estilo de vida; se define el concepto de calidad de vida y sus principales aspectos multidimensionales; se justifica la importancia de evaluar la calidad de vida en enfermos crónicos. Adicionalmente, se resumen algunos trabajos en los que se ha evaluado el importante papel que juegan diferentes variables psicológicas y sociales en el mantenimiento, recuperación o pérdida de la salud en cinco enfermedades crónicas: infarto, diabetes, cáncer, VIH-SIDA, insuficiencia renal.

  1. A crítica feminista na mira da crítica A crítica feminista na mira da crítica

    Directory of Open Access Journals (Sweden)

    Rita Terezinha Schmidt

    2008-04-01

    Full Text Available This essay presents a dialogue with some texts that appeared in an anthology of critical writings about “Brazilian feminisms,” problematizing them and thus providing a productive discussion about the production of knowledge about and by feminist criticism in Brazil. Este artigo apresenta um diálogo com textos presentes em uma antologia crítica sobre “feminismos brasileiros”, problematizando-os e, por conseguinte, gerando uma discussão produtiva acerca da produção de conhecimento sobre e pela crítica feminista no Brasil.

  2. Enfermedad pulmonar obstructiva crónica

    OpenAIRE

    Reinaldo Pino Blanco; Orestes Álvarez Fernández; Juan De Dios Rivero Berovides

    2011-01-01

    La enfermedad pulmonar obstructiva crónica se ha convertido en una de las enfermedades crónicas atendidas con mayor frecuencia en la atención primaria de salud. Produce altas tasas de morbilidad y mortalidad en todo el mundo, con una evolución lenta aunque progresivamente mortal, a pesar de tratarse de una enfermedad prevenible, que depende en gran medida, del hábito de fumar. La prevalencia variará según el consumo de tabaco, y se espera que s...

  3. Crédit et subsistance

    OpenAIRE

    Lazos Chavero, Elena; Villers Ruiz, Lourdes

    2003-01-01

    L'analyse de différentes situations locales fait apparaître que les programmes de développement agricole fondés sur la distribution systématique de crédit échouent généralement en tant que politique de production, mais ont des effets, non recherchés et non prévus par le programmateur, sur la consommation. Dans des conditions écologiques et sociales qui ne permettent pas qu'une application massive de capital se traduise en une augmentation sensible du produit agricole, le crédit apparaît...

  4. Microstructural and mechanical characteristics of Ni–Cr thin films

    Energy Technology Data Exchange (ETDEWEB)

    Petley, Vijay [Gas Turbine Research Establishment, DRDO, Bangalore 93 (India); Sathishkumar, S.; Thulasi Raman, K.H.; Rao, G.Mohan [Department of Instrumentation and Applied Physics, IISc, Bangalore 12 (India); Chandrasekhar, U. [Gas Turbine Research Establishment, DRDO, Bangalore 93 (India)

    2015-06-15

    Highlights: • Ni–Cr thin films of varied composition deposited by DC magnetron co-sputtering. • Thin film with Ni–Cr: 80–20 at% composition exhibits most distinct behavior. • The films were tensile tested and exhibited no cracking till the substrate yielding. - Abstract: Ni–Cr alloy thin films have been deposited using magnetron co-sputtering technique at room temperature. Crystal structure was evaluated using GIXRD. Ni–Cr solid solution upto 40 at% of Cr exhibited fcc solid solution of Cr in Ni and beyond that it exhibited bcc solid solution of Ni in Cr. X-ray diffraction analysis shows formation of (1 1 1) fiber texture in fcc and (2 2 0) fiber texture in bcc Ni–Cr thin films. Electron microscopy in both in-plane and transverse direction of the film surface revealed the presence of columnar microstructure for films having Cr upto 40 at%. Mechanical properties of the films are evaluated using nanoindentation. The modulus values increased with increase of Cr at% till the film is fcc. With further increase in Cr at% the modulus values decreased. Ni–Cr film with 20 at% Ni exhibits reduction in modulus and is correlated to the poor crystallization of the film as reflected in XRD analysis. The Ni–Cr thin film with 80 at% Ni and 20 at% Cr exhibited the most distinct columnar structure with highest electrical resistivity, indentation hardness and elastic modulus.

  5. Experimental study on Cr(Ⅵ) reduction by Pseudomonas aeruginosa

    Institute of Scientific and Technical Information of China (English)

    LIU Yun-guo; XU Wei-hua; ZENG Guang-ming; TANG Chun-fang; LI Cheng-feng

    2004-01-01

    Investigation on Cr(Ⅵ) reduction was conducted using Pseudomonas aeruginosa. The study demonstrated that the Cr(Ⅵ) can be effectively reduced to Cr(Ⅲ) by Pseudomonas aeruginosa. The effects of the factors affecting Cr(Ⅵ) reduction rate including carbon source type, pH, initial Cr(Ⅵ) concentration and amount of cells inoculum were thoroughly studied. Malate was found to yield maximum biotransformation, followed by succinate and glucose, with the reduction rate of 60.86%, 43.76% and 28.86% respectively. The optimum pH for Cr(Ⅵ) reduction was 7.0, with reduction efficiency of 61.71% being achieved. With the increase of initial Cr(Ⅵ) concentration, the rate of Cr(Ⅵ) reduction decreased. The reduction was inhibited strongly when the initial Cr(Ⅵ) concentration increased to 157 mg/L. As the amount of cells inoculum increased, the rate of Cr(Ⅵ) reduction also increased. The mechanism of Cr(Ⅵ) reduction and final products were also analysed. The results suggested that the soluble enzymes appear to be responsible for Cr(Ⅵ) reduction by Pseudomonas aeruginosa, and the reduced Cr(Ⅲ) was not precipitated in the form of Cr(OH)3.

  6. Moessbauer Investigation of Electrodeposited Sn-Zn, Sn-Cr, Sn-Cr-Zn and Fe-Ni-Cr Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmann, E.; Stichleutner, S. [Eoetvoes University, Department of Nuclear Chemistry and Research Group of Nuclear Methods in Structural Chemistry HAS (Hungary); El-Sharif, M.; Chisholm, C. U. [Glasgow Caledonian University (United Kingdom); Sziraki, L.; Homonnay, Z.; Vertes, A. [Eoetvoes University, Department of Nuclear Chemistry and Research Group of Nuclear Methods in Structural Chemistry HAS (Hungary)

    2002-06-15

    {sup 57}Fe and {sup 119}Sn CEMS, XRD and electrochemical measurements were used to investigate the effect of the preparation parameters and the components on the structure and phase composition of electrodeposited Fe-Ni-Cr alloys in connection with their corrosion behavior. XRD of the electrodeposits reflect an amorphous-like character. {sup 57}Fe CEM spectra of Fe-Ni-Cr electrodeposited samples, prepared in a continuous flow plating plastic circulation cell with variation of current density, electrolyte velocity and temperature, can be evaluated as a doublet associated with a highly disordered paramagnetic solid solution phase. This phase was identified earlier in Fe-Ni-Cr electrodeposits that were prepared by another plating method and contained both ferromagnetic and paramagnetic metastable phases. This is the first time that we have succeeded to prepare Fe-Ni-Cr alloys containing only the metastable paramagnetic phase. The effect of the plating parameters on the structure is also analysed by the quadrupole splitting distribution method. {sup 119}Sn CEM spectra of all Sn-containing plated alloys show a broad line envelop which can be decomposed at least into two components. One can be associated with {beta}-tin. The other one can be assigned to an alloy phase. The structure and distribution of microenvironments of these phases depends on the plating parameters especially on the parameters of the reverse pulse applied.

  7. Correlation of microstructure and fracture toughness of advanced 9Cr/CrMoV dissimilarly welded joint

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Qian [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Lu, Fenggui, E-mail: Lfg119@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Xia [Shanghai Turbine Plant of Shanghai Electric Power Generation Equipment Co. Ltd., Shanghai 200240 (China); Yang, Renjie [Shanghai Turbine Works Company, Shanghai 200240 (China); Cui, Haichao [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Gao, Yulai, E-mail: ylgao@shu.edu.cn [State Key Laboratory of Advanced Special Steels, Shanghai University, Shanghai 200072 (China)

    2015-06-25

    In this paper, the fracture toughness and the related microstructure characteristics of dissimilarly welded joint manufactured by advanced 9Cr and CrMoV steels were systematically investigated. The dissimilarly welded joint was fabricated by narrow gap submerged arc welding (NG-SAW) applying multi-layer and multi-pass technique. Fracture toughness, as one of the most important property to assess the reliability of welded joint, was studied for different regions including CrMoV base metal (CrMoV-BM), heat affected zone (HAZ) of CrMoV side (CrMoV-HAZ), weld metal (WM), heat affected zone of 9Cr side (9Cr-HAZ) and 9Cr base metal (9Cr-BM). It was found that the fracture toughness of CrMoV-BM, CrMoV-HAZ and WM was better than that of 9Cr-HAZ and 9Cr-BM. In order to illustrate these results, the microstructure of the whole welded joint was observed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM) detailedly. It was found that the fine high-temperature tempered martensite and bainite in WM, CrMoV-BM and CrMoV-HAZ contribute to the higher fracture toughness, while lower fracture toughness for 9Cr-BM and HAZ was caused by coarse tempered lath-martensite. Furthermore, the fracture morphology showed that ductile fracture occurred in WM and CrMoV side, while brittle fracture appeared in BM and HAZ of 9Cr side.

  8. Effects of Cr on the interdiffusion between Ce and Fe-Cr alloys

    Science.gov (United States)

    Lo, Wei-Yang; Silva, Nicolas; Wu, Yuedong; Winmann-Smith, Robert; Yang, Yong

    2015-03-01

    Fuel cladding chemical interaction (FCCI) has been a long-standing issue for the metallic fuel with a steel cladding in a sodium-cooled fast reactor, particularly for a high burnup fuel. Although the FCCI has been largely improved by alloying the fuels with Zr or Pd elements, applying a physical diffusion barrier between fuel and cladding, and employing advanced ferritic/martensitic (F/M) claddings, there is a scientific knowledge gap in understanding the behavior of chromium and its effects on the interdiffusion between lanthanides and advanced F/M steels that contain 9-12 wt.% Cr. In this paper, we systematically studied the interdiffusion between cerium and Fe-Cr model alloys with Cr contents of 6, 9 and 12 wt.%. Following the thermal annealing at 560 °C for up to 100 h, detailed microstructural characterizations were performed to determine the interdiffusion microstructures, compositional distributions, diffusion kinetics, and phase structures in the interdiffusion zone. This study unambiguously disclosed that, as the Ce diffuses into Fe-Cr model alloys, Cr segregates and precipitates into Cr-rich σ phase consisted of Fe and Cr instead of forming a ternary phase together with Fe and Ce. The precipitation of those nano-sized σ phase particles at the Ce diffusion front would effectively slow down the interdiffusion.

  9. High temperature oxidation behaviors of Ti-Cr alloys with Laves phase TiCr2

    Institute of Scientific and Technical Information of China (English)

    肖平安; 曲选辉; 雷长明; 祝宝军; 秦明礼; 敖晖; 黄培云

    2002-01-01

    The high temperature oxidation behaviors of Ti-Cr alloys containing 18%~35%Cr with Laves phase TiCr2 were investigated at 650~780 ℃ for exposure up to 104 h. The results reveal that chromium content has critical significance to the oxidation resistance of the alloys. The scaling rates of the alloys with less than 21%Cr are higher than those measured for pure titanium, but for the alloys with more than 26%Cr their scaling rate is lowered by 1~2 times, under the same oxidizing conditions. Both an external and an internal oxidation layers were observed. The oxidation resistance enhancement by chromium alloying is contributed to the formation of a continuous and compact chromic oxide interleaf in the scale. Oxidation temperature significantly affects the scaling rates of Ti-Cr alloys, and the mass gain is doubled with a temperature change from 650 ℃ to 700 ℃ or from 700 ℃ to 780 ℃, for the same exposure duration. TiCr2 shows no negative influence on the high temperature oxidation resistance of the alloys.

  10. Natural Cr3+-rich ettringite: occurrence, properties, and crystal structure

    Science.gov (United States)

    Seryotkin, Yurii V.; Sokol, Ella V.; Kokh, Svetlana N.; Murashko, Mikhail N.

    2017-08-01

    Cr3+-rich ettringite with Cr3+→Al substitution and Cr/(Cr + Al) ratios up to 0.40-0.50 was found in mineral assemblages of the Ma'aleh Adumim area of Mottled Zone (Judean Desert). The Cr3+-rich compositions were the latest in the thaumasite → ettringite-thaumasite solid solution → ettringite → ettringite-bentorite solid solution series. The mineral-forming solution was enriched in Cr3+ and had a pH buffered by afwillite at 11-12. Chromium was inherited from larnite rocks produced by high-temperature combustion metamorphic alteration of bioproductive calcareous sediments. The Cr/(Cr + Al) ratios are within 0.10-0.15 in most of the analysed crystals. This degree of substitution imparts pink colouration to the crystals, but does not affect their habit (a combination of monohedra and a prism). The habit changes to pyramid faces in coarse and later Cr3+-bearing crystals as Cr/(Cr + Al) ratios increase abruptly to 0.40-0.50. Single-crystal XRD analysis of one Cr-free and two Cr3+-rich samples and their structure determination and refinement indicate that the Cr-rich crystals (with Cr/(Cr + Al) to 0.3) preserve the symmetry and metrics of ettringite. The Ca-O bonding network undergoes differentiation with increase of Cr3+ concentration at octahedral M sites. The compression of Ca2 and expansion of Ca1 polyhedra sub-networks correlates with the degree of Cr3+→Al substitution.

  11. The Effect of Cr Content on the Oxidation Behavior of Ti-Cr-N Films

    Directory of Open Access Journals (Sweden)

    James E. Krzanowski

    2014-04-01

    Full Text Available Ti1−xCrxN thin-film samples were sputter-deposited with lateral composition gradients x = 0.1–0.9 across each sample. In order to determine the effect of Cr content on oxidation, samples were air-oxidized at temperatures ranging from 650 to 950 °C. The extent and type of oxide formed was characterized using X-ray diffraction. Only minor oxidation was observed for the 650–750 °C temperature range. At 850 °C, films below x = 0.7 showed poor oxidation resistance, with the formation of TiO2 and Cr2O3 oxides, but little oxidation occurred above x = 0.7. At 950 °C, films above x = 0.7 again exhibited the best oxidation resistance. Chromium nitride films, which deposited as Cr2N, were found to begin oxidizing at 750 °C, indicating that the increased oxidation resistance of the higher-Cr Ti-Cr-N films can be attributed to the Ti-induced stabilization of the B1-structured phase. A compositionally-uniform film (x = 0.79 was also deposited and analyzed by XPS before and after oxidation. Oxidation resulted in primarily Cr2O3 at the surface, with some TiO2 also present, with the oxide richer in Cr than the starting film composition. These results suggested that at higher Cr compositions in the film, the oxidation mechanism was controlled by Cr diffusion to the surface.

  12. PREPARING STUDENTS FOR THE TREATMENT OF A NEW TEACHER CONTENT, AN IMPORTANT PREREQUISITE FOR THE SUCCESSFUL IMPLEMENTATION OF THE TASK OF TEACHING

    Directory of Open Access Journals (Sweden)

    Zvezdan Arsić

    2013-12-01

    Full Text Available Success in any type of activity depends on thorough preparation. Processing of new teaching facilities, or the acquisition of new knowledge in the whole course of the educational process is one of the most important prerequisites for success in the implementation of the tasks of teaching. When it comes to this problem, the analysis of available pedagogical-psychological and didactic and methodical literature, indicates that it mainly talks about the preparation of teachers, which is certainly needed. However, the implementation of teaching together and actively participating teachers and students , and the modern conception of school based on the students' activities. The above observations lead us to the conclusion that preparing students for teaching is equally important as the preparation of teachers, although it is somewhat more specific, given their status in the classroom.

  13. Technical prerequisites for efficient drive systems - Fundamentals for SwissEnergy measures; Technische Grundlagen effizienter Antriebssysteme. Grundlagen fuer Aktionen (Massnahmen) von Energieschweiz

    Energy Technology Data Exchange (ETDEWEB)

    Schnyder, G.; Ritz, Ch.

    2007-03-15

    This final report for the Swiss Federal Office of Energy (SFOE) reports on the technical prerequisites necessary for the implementation of various measures that are to be taken to promote efficient electrical drive systems. The document defines the approach taken and describes the methodologies to be used, including market analysis, the collection of basic data, the definition of measures and the acquisition of partners. The potential for making savings is estimated. Eight areas of action are defined, including the organisation of tutorials, exchange of experience, knowledge transfer, basic consulting services, the deployment of consultants, the setting-up of an Internet portal, information transfer in conferences and the optimisation of auxiliaries in domestic installations. A comprehensive annex completes the report.

  14. Magnetostriction and ferroelectric state in AgCrS₂.

    Science.gov (United States)

    Streltsov, Sergey V; Poteryaev, Alexander I; Rubtsov, Alexey N

    2015-04-29

    The band structure calculations in the GGA+U approximation show the presence of additional lattice distortions in the magnetically ordered phase of AgCrS2. The magnetostriction leads to the formation of long and short Cr-Cr bonds in the case when the respective Cr ions have the same or opposite spin projections. These changes in the Cr lattice are accompanied by distortions of the CrS6 octahedra, which in turn lead to the development of spontaneous electric polarization.

  15. CrIS Sensor Temperature Effects on CrIS Radiometric Performance

    OpenAIRE

    Esplin, Mark; Zavyalov, Vladimir; Grant, Kevin; Scott, Deron

    2012-01-01

    The Cross-track Infrared Sounder (CrIS) sensor was launched on the Suomi NPP spacecraft October 28, 2011. The CrIS sensor is a Michelson interferometer with a 3 x 3 detectors for each of three spectral bands: LWIR 650-1095 wavenumbers, MWIR 1210-1750 wavenumbers and SWIR 2155-2550 wavenumbers. The CrIS sensor is performing very well and is generally exceeding the noise, radiometric and spectral performance requirements for its primary weather sensing mission. However, for climate change appli...

  16. Chemical and electrochemical behavior of the Cr(3)/Cr(2) half cell in the NASA Redox Energy Storage System

    Science.gov (United States)

    Johnson, D. A.; Reid, M. A.

    1982-01-01

    The Cr(III) complexes in the NASA Redox Energy Storage System were isolated and identified as Cr(H2O)6(+3) and Cr(H2O)5Cl(+2) by ion exchange chromatography and visible spectrophotometry. The cell reactions during charge-discharge cycles were followed by means of visible spectrophotometry. The spectral bands were resolved into component peaks and concentrations calculated using Beer's Law. During the charge mode Cr(H2O)5Cl(+2) is reduced to Cr(H2O)5Cl(+) and during the discharge mode Cr(H2O)5Cl(+) is oxidized back to Cr(H2O)5Cl(+2). Both electrode reactions occur via a chloride-bridge inner-sphere reaction pathway. Hysteresis effects can be explained by the slow attainment of equilibrium between Cr(H2O)6(+3) and Cr(H2O)5Cl(+2).

  17. High spin polarization and spin splitting in equiatomic quaternary CoFeCrAl Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Bainsla, Lakhan; Mallick, A.I. [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Coelho, A.A. [Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas-UNICAMP, SP 6165, Campinas 13 083-859, Sao Paulo (Brazil); Nigam, A.K. [DCMPMS, Tata Institute of Fundamental Research, Mumbai 4000052 (India); Varaprasad, B.S.D.Ch.S.; Takahashi, Y.K. [Magnetic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Alam, Aftab [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Hono, K. [Magnetic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2015-11-15

    In this paper, we investigate CoFeCrAl alloy by means of ab-initio electronic structure calculations and various experimental techniques. The alloy is found to exist in the B2-type cubic Heusler structure, which is very similar to Y-type (or LiMgPdSn prototype) structure with space group F-43m (#216). Saturation magnetization (M{sub S}) of about 2 µ{sub B}/f.u. is observed at 8 K under ambient pressure, which is in good agreement with the Slater–Pauling rule. M{sub S} values are found to be independent of pressure, which is a prerequisite for half-metals. The ab-initio electronic structure calculations predict half-metallicity for the alloy with a spin slitting energy of 0.31 eV. Importantly, this system shows a high current spin polarization value of 0.67±0.02, as deduced from the point contact Andreev reflection measurements. Linear dependence of electrical resistivity with temperature indicates the possibility of reasonably high spin polarization at elevated temperatures (~150 K) as well. All these suggest that CoFeCrAl is a promising material for the spintronic devices. - Highlights: • The ab-initio calculations predict half-metallic nature for the alloy. • Saturation magnetization (M{sub S}) gives characteristics of half-metallic nature. • Current spin polarization (P) value of 0.67±0.02 is deduced from PCAR measurements. • Deduced P is higher than those obtained for many ternary and/or quaternary alloys. • Resistivity behavior gives signature of high P at elevated temperatures.

  18. Créer une haie vive

    OpenAIRE

    Gnahoua, Guy Modeste; Louppe, Dominique

    2003-01-01

    4 p.; Fiche technique; Fiche technique pour la création d'une haie vive : définition, espèces concernées, conception, techniques d'installation, entretien, coûts, impacts, conditions d'application

  19. Silicon Strengthened CrAlVN Coatings

    Institute of Scientific and Technical Information of China (English)

    Qiang LI; Yue-xiu QIU; Bo LI; Dong-liang ZHAO; De-en SUN; De-hui LI

    2015-01-01

    CrAlVN coatings are of good intrinsic mechanical and tribological properties but lack of strength.Silicon can provide nitride coating high strength and excellent oxidation resistance.Logically,the combination of CrAlVN and Si should provide a good candidate for dry machining.The effect of silicon content on CrAlSiVN coating′s me-chanical,tribological properties and oxidation resistance was investigated.The coatings were deposited on cemented tungsten carbide and Si wafer (100)substrates in an in-line magnetron sputtering system.Grazing incidence X-ray diffractometer,scanning electron microscopy,atomic force microscopy,transmission electron microscopy,electron probe micro-analyzer,X-ray photoelectron spectroscopy and Auger electron spectroscopy were employed to charac-terize the microstructure and chemistry.Nanoindentation and ball-on-disc tribo-tester were used in characterization of the mechanical and tribological properties.Incorporating with silicon,the CrAlVN coating was strengthened (hard-ness:21.2 GPa up to 38.7 GPa);even after 2 h exposure to 700 ℃ in air,the hardness still maintains at 11.0 GPa.

  20. Hazard Evaluation for 244-CR Vault

    Energy Technology Data Exchange (ETDEWEB)

    GRAMS, W.H.

    1999-08-19

    This document presents the results of a hazards identification and evaluation performed on the 244-CR Vault to close a USQ (USQ No.TF-98-0785, Potential Inadequacy in Authorization Basis (PIAB): To Evaluate Miscellaneous Facilities Listed In HNF-2503 And Not Addressed In The TWRS Authorization Basis) that was generated as part of an evaluation of inactive TWRS facilities.

  1. Characterization of Cr ion exchange with hydrotalcite.

    Science.gov (United States)

    Terry, Patricia A

    2004-11-01

    Experiments were performed to characterize the removal of chromium from water with uncalcined hydrotalcite, a clay mineral ion exchange media. The process was characterized as a function of pH, temperature, contact time, and both Cr and hydrotalcite concentrations. A Freundlich isotherm, used to describe adsorption equilibria, was used as a model and Freundlich constants were determined. The kinetics of the ion exchange reaction were also modeled using a pseudo-first order reaction rate. Finally, an equilibrium stage process was modeled with sequential batch separations to determine if hydrotalcite ion exchange could reduce aqueous Cr levels to below the EPA limit of 0.1mgl(-1). It was shown that the process is highly pH dependent, only yielding significant removals at pH levels between 2.0 and 2.1. While hydrotalcite concentration, Cr concentration, and time did effect the ion exchange, temperature was not found to be a factor. Under optimal conditions, maximum removals of greater than 95% were achieved. Finally, sequential batch tests performed on initial Cr solutions ranging from 5mgl(-1) to 40mgl(-1), demonstrated that the water could be purified to a level that was not statistically different than the EPA limit, thus demonstrating the applicability of hydrotalcite ion exchange.

  2. Thermodynamics of Co/Cr superlattices

    Science.gov (United States)

    Mukherjee, T.; Sahoo, S.; Skomski, R.; Sellmyer, D. J.; Binek, Ch.

    2008-03-01

    Progress in ultra thin film growth has resulted in many novel surface and interface induced properties of artificial heterostuctures. Here, we study magnetic superlattices of ultrathin Co and Cr films grown by Molecular Beam Epitaxy methodology at a base pressure below 1x10-10 mbar. Our approach is based on controlling two distinct magnetic degrees of freedom. First, the critical temperature, Tc, of individual Co films is tailored via geometrical confinement of the correlation length perpendicular to the film. Various thickness dependent values, Tc(d), between zero and the bulk Curie temperature of 1388 K are realized. Second, the Tc-tailored Co films are antiferromagnetically coupled through Cr interlayer films. The oscillating coupling strength is tailored via the Cr interlayer thickness. The resulting thermodynamic properties of such Co/Cr superlattices are studied with the help of SQUID magnetometry. Particular emphasis is laid on tailoring magnetic entropy changes in the vicinity of room temperature. X-ray diffraction and X-ray reflectivity are used to correlate structural data with the magnetic properties.

  3. Effect of Cr/C Ratio on Microstructure and Corrosion Performance of Cr3C2-NiCr Composite Fabricated by Laser Processing

    Science.gov (United States)

    Lou, Deyuan; Liu, Dun; He, Chunlin; Bennett, Peter; Chen, Lie; Yang, Qibiao; Fearon, Eamonn; Dearden, Geoff

    2016-01-01

    The present study focuses on the effect of different Cr/C ratios on the microstructure, microhardness, and corrosion resistance of Ni-based laser clad hardfacings, reinforced by in situ synthesized chromium carbide particles. Cr3C2-NiCr composites have been laser processed with graphite/Cr/Ni powder blends with varying Cr/C ratios. Following phase analysis (x-ray diffraction) and microstructure investigation (scanning electron microscopy; energy dispersive x-ray analysis; transmission electron microscopy), the solidification of laser melt pool is discussed, and the corrosion resistances are examined. Several different zones (planar, dendritic, eutectic and re-melt zone) were formed in these samples, and the thicknesses and shapes of these zones vary with the change of Cr/C ratio. The sizes and types of carbides and the content of reserved graphite in the composites change as the Cr/C ratio varies. With the content of carbides (especially Cr3C2) grows, the microhardness is improved. The corrosive resistance of the composites to 0.2M H2SO4 aqueous solution decreases as the Cr/C ratio reduces owing to not only the decreasing Cr content in the NiCr matrix but also the galvanic corrosion formed within the carbide and graphite containing Ni matrix.

  4. Kinetics and Mechanism of the Hydrogenation of CpCr(CO)3•/[CpCr(CO)3]2 Equilibrium to CpCr(CO)3H

    Energy Technology Data Exchange (ETDEWEB)

    Norton, Jack R.; Spataru, Tudor; Camaioni, Donald M.; Lee, Suh-Jane; Li, Gang; Choi, Jongwook; Franz, James A.

    2014-05-26

    The kinetics of the hydrogenation of 2 CpCr(CO)3•/[CpCr(CO)3]2 to CpCr(CO)3H has been investigated. The reaction is second-order in Cr and first-order in H2, with a rate constant of 45 M 2s 1 at 25 °C in benzene. DFT calculations rule out an H2 complex as an intermediate, and suggest (a) end-on approach of H2 to one Cr of [CpCr(CO)3]2 as the Cr-Cr bond undergoes heterolytic cleavage, (b) heterolytic cleavage of the coordinated H2 between O and Cr, and (c) isomerization of the resulting O-protonated CpCr(CO)2(COH) to CpCr(CO)3H. The work at Pacific Northwest National Laboratory (PNNL) was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences; Battelle operates PNNL for DOE.

  5. In-situ transmission electron microscopy study of surface oxidation for Ni–10Cr and Ni–20Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Langli; Zou, Lianfeng; Schreiber, Daniel K.; Baer, Donald R.; Bruemmer, Stephen M.; Zhou, Guangwen; Wang, Chong-Min

    2016-03-01

    The early-stage oxidation of Ni (001) thin films alloyed with 10 or 20 at% Cr at 700 °C has been directly visualized using environmental transmission electron microscopy. Independent of Cr concentration, the oxidation initiates via the nucleation of surface NiO islands and subsurface Cr2O3. The NiO grows and transitions into a continuous film, followed by the nucleation and growth of NiCr2O4 islands through the outer oxide. The Cr concentration plays a more critical role in the later stages of the oxidation. A continuous and more protective Cr2O3 sublayer is established for Ni-20at% Cr, while the Cr2O3 sublayer for Ni-10at%Cr is discontinuous for Ni-10at%Cr. Oxidation persists on the lower Cr alloy where NiO whiskers are observed to preferentially nucleate and grow from the NiCr2O4 islands. It is suggested that short-circuit diffusion of Ni occurs along the NiCr2O4 interfaces through the discontinuous Cr2O3 layer in Ni-10at%Cr to facilitate the selective nucleation of NiO whiskers on the NiCr2O4 surfaces. Conversely, the protective nature of the continuous Cr2O3 film in Ni-20at%Cr blocks this short-circuit pathway and prevents the formation of additional NiO on the surface in the early stage oxidation.

  6. Standard Specification for Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2014-01-01

    Standard Specification for Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe

  7. Flora y fauna crónica

    Directory of Open Access Journals (Sweden)

    Susana Chávez-Silverman

    2004-01-01

    Full Text Available “Flora & Fauna Crónica” is from the book, Killer Crónicas, which will be published by the University of Wisconsin Press in 2004. This collection of chronicles began in 2000, after Susana was awarded a fellowship by the US National Endowment for the Humanities (NEH for a project on contemporary Argentine women's poetry. She spent thirteen months in Buenos Aires where, in addition to research and writing on her official (academic book, she began to send bilingual, punning “letters from the southern [cone] front” to colleagues and friends by email. Susana says: “Living in Buenos Aires, that gorgeous, turn of the century city in a country on the brink of (economic collapse—home to many of the authors and artists I had long admired (Borges, Cortázar, Alfonsina Storni, Alejandra Pizarnik, and before them the foundational Romantics, Sarmiento and Echeverría—brought out a sense of self, dis/placed yet oddly at home, in a cultural, linguistic and even tangible way. In Buenos Aires, the fragmented parts of me, the voices, cultures, and places inside of me, rubbed up against each other and struck fire. I called my email missives “Crónicas,” inspired by the somewhat rough-hewn, journalistic, often fantastic first-hand accounts sent “home” by the early conquistadores, and refashioned by modern-day counterparts such as Carlos Monsiváis, Elena Poniatowska, and Cristina Pacheco.” One of Susana’s crónicas, “Anniversary Crónica,” inspired by the wedding anniversary of Susana’s parents and by the so-called “Soweto Riots” in South Africa, was recently awarded First prize in Personal Memoir in the Chicano Literary Excellence Contest sponsored by the U.S. national literary magazine el Andar.

  8. The Hot Corrosion Performance of NiCr-Cr3 C2 Cermet Coating to Boiler Tube

    Institute of Scientific and Technical Information of China (English)

    DINGZhang-xiong; TUGuo-fu

    2004-01-01

    Three kinds of NiCr-Cr3 C2 cermet coatings were designed and deposited by the subsonic velocity flame spraying, and their performances of hot corrosion performance were evaluated in comt)arison with 102G,20G boiler tube steel, FeCrAl, NiCrTi, Ni5OCr and NiCrAIMoFe-Cr3 C2 coatings, which are widely used at present for protection of boiler tubes. Meanwhile, the influence of sealer on the hot corrosion resistance of warious coatings and the mechanisms of coating corrosion were explored.

  9. Reaction diffusion in the NiCrAl and CoCrAl systems

    Science.gov (United States)

    Levine, S. R.

    1978-01-01

    The paper assesses the effect of overlay coating and substrate composition on the kinetics of coating depletion by interdiffusion. This is accomplished by examining the constitution, kinetics and activation energies for a series of diffusion couples primarily of the NiCrAl/Ni-10Cr or CoCrAl/Ni-10Cr type annealed at temperatures in the range 1000-1205 C for times up to 500 hr. A general procedure is developed for analyzing diffusion in multicomponent multiphase systems. It is shown that by introducing the concept of beta-source strength, which can be determined from appropriate phase diagrams, the Wagner solution for consumption of a second phase in a semiinfinite couple is successfully applied to the analysis of MCrAl couples. Thus, correlation of beta-recession rate constants with couple composition, total and diffusional activation energies, and interdiffusion coefficients are determined.

  10. 42CrMo与42CrMo4的区别

    Institute of Scientific and Technical Information of China (English)

    李治平; 王清辉

    2015-01-01

    本文从化学成分、机械性能、淬透性等各个方面讲述了42CrMo 与42CrMo4的区别,以便我们的机械设计人员、机械工艺人员了解其异同,根据具体应用情况选用两种牌号。

  11. PREPARATION AND PROPERTIES OF Ni-Cr AND Fe-Cr-Al FILMS BY VACUUM EVAPORATION

    Institute of Scientific and Technical Information of China (English)

    X. W. Shi; Z.Y. Liu; D.C. Zeng; C.M. Li

    2003-01-01

    Ni-Cr and Fe-Cr-Al films deposited on the Al2O3 substrate are studied by a method of vacuum evaporation in this paper. Influence of resistance value on density and evaporation parameters of the films reveals that the resistance of films and the adhesion of films to substrates are determined by the evaporation time and the substrate temperate under the condition of the maximum vacuity of 6.2×10-4 pa, respectively.

  12. Fractography and Porosity Analysis of Cr and Cr-Mo PM Steels

    Directory of Open Access Journals (Sweden)

    Kulecki P.

    2016-09-01

    Full Text Available The aim of the study was to evaluate the effect of processing variables on the porosity and fractography of Cr and Cr-Mo PM steels. The measurements were performed on sintered steels made from commercial Höganäs pre-alloyed powders: Astaloy CrA, Astaloy CrL and Astaloy CrM with two different carbon concentrations (0.2% and 0.6% added in the form of ultra fine graphite powder grade C-UF. Following mixing in Turbula mixer for 30 minutes, green compacts were single-action pressed at 660 MPa according to PN-EN ISO 2740 standard. Sintering was carried out in a laboratory horizontal tube furnace at 1120°C and 1250°C for 60 minutes, in an atmosphere containing 5%H2 and 95%N2. After sintering, the samples were tempered at 200°C for 60 minutes in air. For porosity evaluation computer software was employed. Hitachi S-3500M SEM equipped with EDS (made by Noran was employed for fracture analysis. The steel based on Astaloy CrM pre-alloyed powder is characterized by fine pores and good mechanical properties. When sintered at 1250°C, it had area of pores approx. 7.12 μm2, ultimate tensile strength (UTS about 679 MPa and elongation about 4%. The steels were characterized by ductile/cleavage and ductile fractures.

  13. Targeting of influenza epitopes to murine CR1/CR2 using single-chain antibodies.

    Science.gov (United States)

    Prechl, J; Tchorbanov, A; Horváth, A; Baiu, D C; Hazenbos, W; Rajnavölgyi, E; Kurucz, I; Capel, P J; Erdei, A

    1999-05-01

    Single-chain variable fragment (scFv) antibodies are genetically engineered molecules comprising the variable regions responsible for specific binding. scFv that recognize certain surface molecules on professional antigen presenting cells could therefore be suitable for targeting Ag to these cells. We have produced an scFv that recognizes murine complement receptors 1 and 2 (CR1/CR2) and genetically fused it with different numbers of influenza hemagglutinin peptides which contain both B and T cell epitopes. The CR1/CR2 specific hybridoma 7G6 was used for RT-PCR to obtain the variable regions, which were then combined to create an scFv fragment. The influenza hemagglutinin intersubunit peptide HA317-41 (IP) was engineered to the N terminus of the scFv in one, two or three copies. The so obtained IP(1-3)7G6scFv still bound the complement receptors; the peptides in the construct were recognized by the peptide specific monoclonal IP2-11-1 on Western blots and ELISAs. The CR1/CR2 positive B lymphomas A20 and 2PK3 presented the peptide to an I-Ed restricted IP specific T cell hybridoma more efficiently when incubated with the IP(1)7G6 constructs as compared to the free peptide. The results suggest that scFv could work as targeting devices in subunit vaccines.

  14. Unconventional exchange bias in CoCr2O4/Cr2O3 nanocomposites

    Science.gov (United States)

    Guo, S.; Liu, X. H.; Cui, W. B.; Liu, W.; Zhao, X. G.; Li, D.; Zhang, Z. D.

    2009-03-01

    Unconventional exchange bias (EB) has been studied in CoCr2O4/Cr2O3 nanocomposites, in which the Curie temperature of the ferrimagnetic CoCr2O4 is much lower than the Néel temperature of the antiferromagnetic Cr2O3. A negative EB field of about 2.5 kOe at 5 K is achieved upon cooling in a field of 30 kOe. Meanwhile, the coercivity of the CoCr2O4 nanoparticles has been enhanced significantly by coupling with Cr2O3. The effect of the cooling field on the EB field and coercivity at 10 K has also been investigated. The domain-state model is used to interpret the unconventional EB. Cooling field may play a decisive role in the creation of the interfacial spin configuration for the unconventional EB, not only by exchange interaction between the induced magnetization of a polarized paramagnet and interfacial spins of an antiferromagnet but also by Zeeman interaction between the domain-state surplus magnetization and the external field.

  15. A mechanical and tribological study of Cr/CrN multilayer coatings

    Energy Technology Data Exchange (ETDEWEB)

    Arias, D.F., E-mail: diegomas@gmail.com [Grupo GEMA, Universidad Católica de Pereira, Pereira (Colombia); Gómez, A. [Laboratório de Fenômenos de Superficie, Escola Politécnica, Universidade de Sao Paulo, Sao Paulo (Brazil); Pontificia Universidad Javeriana Cali (Colombia); Vélez, J.M. [Escuela de Ingeniería de Materiales, Universidad Nacional de Colombia Sede Medellín (Colombia); Souza, R.M. [Laboratório de Fenômenos de Superficie, Escola Politécnica, Universidade de Sao Paulo, Sao Paulo (Brazil); Olaya, J.J. [Departamento de Ingeniería Mecánica y Mecatrónica, Universidad Nacional de Colombia, Bogotá (Colombia)

    2015-06-15

    Multilayer Cr/CrN coatings with different periodicities were grown on silicon substrates by means of a magnetron sputtering technique. Thin films with only Cr or CrN were also grown, in order to use them as reference samples. Structural, morphological, mechanical and tribological characterization were carried out by using X-ray diffraction (XRD), atomic force microscopy (AFM), nanohardness and nanoscratch techniques, respectively. The characterization results were analyzed as a function of the bilayer thickness (period). In general, the multilayer hardness value increased with the decrease in period. In addition, the validity of the Hall-Petch relationship was confirmed for grain sizes and period values greater than 146 nm and 333 nm, respectively. The coefficient of friction (COF) increased with increasing load, which indicates the contribution of the adhesion to the COF. - Highlights: • Multilayer Cr/CrN coatings with layer thickness between 200 and 1000 nm were grown. • Neither bias voltage not temperature were applied during deposition. • The hardness improves with the increase of the number of bilayers. • The wear rate decreases with the increase of the number of bilayers.

  16. Toxic effects of Cr(VI) and Cr(III) on energy metabolism of heterotrophic Euglena gracilis.

    Science.gov (United States)

    Jasso-Chávez, Ricardo; Pacheco-Rosales, Angélica; Lira-Silva, Elizabeth; Gallardo-Pérez, Juan Carlos; García, Noemí; Moreno-Sánchez, Rafael

    2010-11-15

    To assess the toxic effect of Cr on energy metabolism, heterotrophic Euglena gracilis was grown in a medium that prompts high yield biomass and in the presence of different Cr(VI) or Cr(III) concentrations. The cell growth IC₅₀ value was 12 and >250μM for Cr(VI) and Cr(III), respectively; in these cells chromium was accumulated and a fraction compartmentalized into mitochondria, and synthesis of cysteine and glutathione was induced. Respiration of control isolated mitochondria was strongly inhibited by added Cr(VI) or Cr(III) with L-lactate or succinate as substrates. In turn, cellular and mitochondrial respiration, respiratory Complexes I, III and IV, glycolysis and cytosolic NAD(+)-alcohol and -lactate dehydrogenases from cells cultured with Cr(VI) were significantly lower than control, whereas AOX and external NADH dehydrogenase activities were unaltered or increased, respectively. Addition of Cr(VI) or Cr(III) to isolated mitochondria or cytosol from control- or Cr(VI)-grown cells induced inhibition of respiration, respiratory Complexes III, IV and AOX, and glycolytic pyruvate kinase; whereas Complex I, external NADH dehydrogenase, and other glycolytic enzymes were unaffected. Protein contents of mitochondrial Complexes I, III, IV and V, and ANT were diminished in Cr(VI)-grown cells. Decreased respiration and glycolysis induced by Cr(VI) resulted in lower cellular ATP content. Results suggested that Cr(VI) cytotoxicity altered gene expression (as widely documented) and hence enzyme content, and induced oxidative stress, but it was also related with direct enzyme inhibition; Cr(III) was also cytotoxic although at higher concentrations. These findings establish new paradigms for chromium toxicity: Cr(VI) direct enzyme inhibition and non-innocuous external Cr(III) toxicity.

  17. Microstructure and Sliding Wear Performance of Cr7C3-(Ni,Cr)3(Al,Cr) Coating Deposited from Cr7C3 In Situ Formed Atomized Powder

    Science.gov (United States)

    Zhu, Hong-Bin; Shen, Jie; Gao, Feng; Yu, Yueguang; Li, Changhai

    2017-01-01

    This work is aimed at developing a new type of Cr7C3-(Ni,Cr)3(Al,Cr) coating for parts used in heavy-duty diesel engines. The feedstock, in which the stripe-shaped Cr7C3 was in situ formed, was firstly prepared by vacuum melting and gas atomization and then subjected by high-velocity oxy-fuel spraying to form the coatings. The carbon content, microstructure and phase constitution of the powders, as well as the sprayed coatings, were analyzed by chemical analysis, SEM and XRD. The hardness and sliding wear performance of the sprayed coatings were also tested and compared to a commercial Cr3C2-NiCr coating used on piston rings. The results showed that the content of carbon in feedstock was almost the same as designed, and that the volume content of in situ formed Cr7C3 was increased with carbon and chromium added. The major phases of the powders and sprayed coatings are Cr7C3 and Cr-alloyed Ni3Al. Only a small amount of carbon lost during the spraying process. As Cr7C3 content increased in the coatings, the microhardness at room temperature was firstly increased to about 1000Hv0.3. The microhardness of the coatings stayed almost constant, while the testing temperature was raised up to 700 °C for 0.5 h, which illustrates the potential application of the investigated coatings under high temperature conditions. The coatings containing 70 and 77 vol.% Cr7C3 showed the most promising wear resistance, lower friction coefficient and better tribological compatibility to gray cast iron counterpart than other tested Cr7C3-(Ni,Cr)3(Al,Cr) coatings and the reference Cr3C2-NiCr coating.

  18. Microstructure and Sliding Wear Performance of Cr7C3-(Ni,Cr)3(Al,Cr) Coating Deposited from Cr7C3 In Situ Formed Atomized Powder

    Science.gov (United States)

    Zhu, Hong-Bin; Shen, Jie; Gao, Feng; Yu, Yueguang; Li, Changhai

    2016-12-01

    This work is aimed at developing a new type of Cr7C3-(Ni,Cr)3(Al,Cr) coating for parts used in heavy-duty diesel engines. The feedstock, in which the stripe-shaped Cr7C3 was in situ formed, was firstly prepared by vacuum melting and gas atomization and then subjected by high-velocity oxy-fuel spraying to form the coatings. The carbon content, microstructure and phase constitution of the powders, as well as the sprayed coatings, were analyzed by chemical analysis, SEM and XRD. The hardness and sliding wear performance of the sprayed coatings were also tested and compared to a commercial Cr3C2-NiCr coating used on piston rings. The results showed that the content of carbon in feedstock was almost the same as designed, and that the volume content of in situ formed Cr7C3 was increased with carbon and chromium added. The major phases of the powders and sprayed coatings are Cr7C3 and Cr-alloyed Ni3Al. Only a small amount of carbon lost during the spraying process. As Cr7C3 content increased in the coatings, the microhardness at room temperature was firstly increased to about 1000Hv0.3. The microhardness of the coatings stayed almost constant, while the testing temperature was raised up to 700 °C for 0.5 h, which illustrates the potential application of the investigated coatings under high temperature conditions. The coatings containing 70 and 77 vol.% Cr7C3 showed the most promising wear resistance, lower friction coefficient and better tribological compatibility to gray cast iron counterpart than other tested Cr7C3-(Ni,Cr)3(Al,Cr) coatings and the reference Cr3C2-NiCr coating.

  19. Thermal stability of Al-Cr-N hard coatings

    Energy Technology Data Exchange (ETDEWEB)

    Willmann, H. [Materials Center Leoben, Franz-Josef Strasse 13, 8700 Leoben (Austria) and IFM Material Physics, Division of Thin Film Physics, Linkoeping University, 58183 Linkoeping (Sweden)]. E-mail: herbert.willmann@unileoben.ac.at; Mayrhofer, P.H. [Department of Physical Metallurgy and Materials Testing, University of Leoben, 8700 Leoben (Austria); Materials Chemistry, RWTH-Aachen, 52074 Aachen (Germany); Persson, P.O.A. [IFM Material Physics, Division of Thin Film Physics, Linkoeping University, 58183 Linkoeping (Sweden); FEI Company, 5651 GG Eindhoven (Netherlands); Reiter, A.E. [Balzers Ltd., 9496 Balzers (Liechtenstein); Hultman, L. [IFM Material Physics, Division of Thin Film Physics, Linkoeping University, 58183 Linkoeping (Sweden); Materials Chemistry, RWTH-Aachen, 52074 Aachen (Germany); Mitterer, C. [Department of Physical Metallurgy and Materials Testing, University of Leoben, 8700 Leoben (Austria); Christian Doppler Laboratory for Advanced Hard Coatings, University of Leoben, 8700 Leoben (Austria)

    2006-06-15

    Heat treatment of arc-evaporated cubic Al{sub 0.7}Cr{sub 0.3}N hard coatings in Ar up to 1450 deg. C causes precipitation of AlN. The Cr-enriched matrix transforms into Cr via Cr{sub 2}N under N{sub 2} release. These reactions are investigated by simultaneous thermal analysis, mass spectrometry, X-ray diffraction, and analytical transmission electron microscopy.

  20. Deficiency of complement receptors CR2/CR1 in Cr2⁻/⁻ mice reduces the extent of secondary brain damage after closed head injury.

    Science.gov (United States)

    Neher, Miriam D; Rich, Megan C; Keene, Chesleigh N; Weckbach, Sebastian; Bolden, Ashley L; Losacco, Justin T; Patane, Jenée; Flierl, Michael A; Kulik, Liudmila; Holers, V Michael; Stahel, Philip F

    2014-05-24

    Complement activation at the C3 convertase level has been associated with acute neuroinflammation and secondary brain injury after severe head trauma. The present study was designed to test the hypothesis that Cr2-/- mice, which lack the receptors CR2/CD21 and CR1/CD35 for complement C3-derived activation fragments, are protected from adverse sequelae of experimental closed head injury. Adult wild-type mice and Cr2-/- mice on a C57BL/6 genetic background were subjected to focal closed head injury using a standardized weight-drop device. Head-injured Cr2-/- mice showed significantly improved neurological outcomes for up to 72 hours after trauma and a significantly decreased post-injury mortality when compared to wild-type mice. In addition, the Cr2-/- genotype was associated with a decreased extent of neuronal cell death at seven days post-injury. Western blot analysis revealed that complement C3 levels were reduced in the injured brain hemispheres of Cr2-/- mice, whereas plasma C3 levels remained unchanged, compared to wild-type mice. Finally, head-injured Cr2-/- had an attenuated extent of post-injury C3 tissue deposition, decreased astrocytosis and microglial activation, and attenuated immunoglobulin M deposition in injured brains compared to wild-type mice. Targeting of these receptors for complement C3 fragments (CR2/CR1) may represent a promising future approach for therapeutic immunomodulation after traumatic brain injury.

  1. Production & Consumption Situation and Development Prospect of Chinese CR

    Institute of Scientific and Technical Information of China (English)

    Cui Xiaoming

    2012-01-01

    1. Production Situation By the end of 2011, the total production capacity of Chinese CR had reached 83,000 tons, accounting for 19.44% of the total CR production capacity in the world. In the next few years, there are still some Chinese manufacturers planning to build or expand CR production device,

  2. Conformal mappings and CR mappings on the Engel group

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We show that conformal mappings between the Engel groups are CR or anti-CR mappings. This reduces the determination of conformal mappings to a problem in the theory of several complex analysis.The result about the group of CR automorphisms is used to determine the identity component of the group of conformal mappings on the Engel group.

  3. Conformal mappings and CR mappings on the Engel group

    Institute of Scientific and Technical Information of China (English)

    WU QingYan; WANG Wei

    2009-01-01

    We show that conformal mappings between the Engel groups are CR or anti-CR mappings.This reduces the determination of conformal mappings to a problem in the theory of several complex analysis. The result about the group of CR automorphisms is used to determine the identity component of the group of conformal mappings on the Engel group.

  4. Biosorption mechanism of Cr (Ⅵ) onto cells of Synechococcus sp.

    Institute of Scientific and Technical Information of China (English)

    SHEN Li; XIA Jin-lan; HE Huan; NIE Zhen-yuan; QIU Guan-zhou

    2007-01-01

    The biosorption mechanism of Cr (Ⅵ) ions on Synechococcus sp. biosorbent was studied by analyzing the biosorption kinetics as well as speciation change and bond formation during the biosorption process. The kinetics study shows that the adsorption process of Cr (Ⅵ) consists of a very fast stage in the first several minutes, in which more than half of the saturation adsorption is attained, and a slower stage that approximately follows the first order kinetic model, basically Freundlich isotherm models were observed. Comparative studies of FT-IR spectra of K2Cr2O7, free cells ofSynechococcus sp, and Cr-bound cells ofSynechococcus sp.show that the speciation of chromium that binds to the cells of Synechococcus sp. is Cr (Ⅲ), instead of Cr (Ⅵ), and the carboxylic,alcoholic, amido and amino groups may be involved in the binding of Cr (Ⅲ). Integrative analyses of the surface electric potential,the effect of pH value on adsorption behavior of Cr (Ⅵ), and the results of FT-IR show that the biosorption of Cr (Ⅵ) follows two subsequent steps, biosorption of Cr2O72- by electrostatical force at the protonated active sites and reduction of Cr2O72- to Cr3+ by the reductive groups on the surface of the biosorbents.

  5. Behaviour of Z phase in 9–12%Cr steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John

    2006-01-01

    –12%), Z phase precipitates much faster than in 9%Cr steels. Precipitation of Z phase is associated with dissolution of MX carbonitrides, and causes a breakdown in long term creep strength in 9–12%Cr steels. High Cr steels show creep instabilities accompanied with Z phase precipitation, whereas low Cr...... steels show good long term creep stability. A niobium free CrVN variant of the modified Z phase was observed for the first time during the course of this work. The solution temperature of the Cr(V,Nb)N and CrVN modified Z phases was found to be close to 800uC for 11–12%Cr steels, much lower than the 1200......The literature on the behaviour of modified Z phase Cr(V,Nb)N in creep resistant martensitic 9–12%Cr steels is briefly reviewed. Ten different 9–12%Cr steels were investigated after prolonged exposure at 600–660uC; the modified Z phase was found in all of them. In steels with high Cr content (11...

  6. Effects of Cu(II on the Adsorption Behaviors of Cr(III and Cr(VI onto Kaolin

    Directory of Open Access Journals (Sweden)

    Juanjuan Liu

    2016-01-01

    Full Text Available The adsorption of Cr(III or Cr(VI in the absence and presence of Cu(II onto kaolin was investigated under pH 2.0–7.0. Results indicated that the adsorption rate was not necessarily proportional to the adsorption capacity. The solutions’ pH values played a key role in kaolin zeta potential (ζ, especially the hydrolysis behavior and saturation index of heavy metal ions. In the presence of Cu(II, qmixCr(III reached the maximum adsorption capacity of 0.73 mg·g−1 at pH 6.0, while the maximum adsorption capacity for the mixed Cr(VI and Cu(II system (qmixCr(VI was observed at pH 2.0 (0.38 mg·g−1. Comparing the adsorption behaviors and mechanisms, we found that kaolin prefers to adsorb hydrolyzed products of Cr(III instead of Cr3+ ion, while adsorption sites of kaolin surface were occupied primarily by Cu(II through surface complexation, leading to Cu(II inhibited Cr(VI adsorption. Moreover, Cr(III and Cr(VI removal efficiency had a positive correlation with distribution coefficient Kd. Cr(III and Cr(VI removal efficiency had a positive correlation with distribution coefficient Kd and that of adsorption affinities of Cr(III or Cr(VI on kaolin was found to be Kd Cr(III Kd Cr(VI-Cu(II.

  7. Cr6Te8(PEt3)6 and a Molecule-Based Synthesis of Cr3Te4

    NARCIS (Netherlands)

    Hessen, B.; Siegrist, T.; Palstra, T.; Tanzler, S.M.; Steigerwald, M.L.

    1993-01-01

    The molecular cluster compound Cr6Te8(PEt3)6 (1) is formed by the reaction of TePEt3 with either (Et3P)2Cr(allyl)2 or Cr(2,4-dimethylpentadienyl)2. This compound can be converted to the extended inorganic solid state compound Cr3Te4 by simple thermolysis. We have determined the structure of the

  8. High temperature properties of CrAlN, CrAlSiN and AlCrSiN coatings - Structure and oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Polcar, Tomas, E-mail: polcar@fel.cvut.cz [Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 (Czech Republic); SEG-CEMUC - Department of Mechanical Engineering, University of Coimbra, Rua Luis Reis Santos, P-3030 788 Coimbra (Portugal); Cavaleiro, Albano [SEG-CEMUC - Department of Mechanical Engineering, University of Coimbra, Rua Luis Reis Santos, P-3030 788 Coimbra (Portugal)

    2011-09-15

    Highlights: {yields} Deposition and structural analysis of CrAln, CrAlSiN and AlCrSiN coatings. {yields} In-situ XRD analysis at high temperature. {yields} AlCrSiN coating showed the highest oxidation resistance and thermal stability. {yields} CrAlN outperformed CrAlSiN film both in oxidation resistance and thermal stability. - Abstract: CrAlN, CrAlSiN and AlCrSiN coatings were deposited by cathodic arc deposition technique from composite targets. Three targets were used: (i) Cr/Al ratio close to 1, (ii) Cr/Al ratio close to 1 with Si addition, and (iii) Cr/Al ratio close to 1/2 and Si addition. Nitrogen flow was kept constant during the depositions. The Cr/Al ratio of the films, measured by electron probe microanalysis (EPMA), was similar to that of the target and the silicon content was in the range 3-4 at.%. The coatings were deposited onto FeCrAl alloy and WC/Co mirror-polished substrates. To analyze the coating structure, X-ray photoelectron (XPS) and X-ray diffraction (XRD) analysis were used. The evolution of the coating structure up to 1000 deg. C was in situ measured in a XRD apparatus equipped with heating plate. The films oxidation behavior was characterized by thermogravimetric analysis (TGA) at two selected temperatures. The annealed coatings were analyzed by XRD and scanning electron microscopy with energy-dispersive X-ray spectroscopy (EDX). CrAlSiN showed low oxidation resistance being partially oxidized at 800 deg. C. Moreover, the film exhibited low thermal stability, since the cubic nitride phases transformed to hexagonal nitrides at relatively low temperatures. CrAlN oxidation behavior was more promising; nevertheless, AlCrSiN showed excellent thermal stability with cubic nitrides observed even after heating to 1300 deg. C. The oxidation of this film at 900 and 1000 deg. C was negligible.

  9. Os limites da crítica

    Directory of Open Access Journals (Sweden)

    Gerbase, Carlos

    2006-01-01

    Full Text Available A importância da crítica cinematográfica é indiscutível, assim como a necessidade de que o crítico tenha ampla liberdade para exercer seu ofício. Isso não quer dizer, contudo, que ele possa dizer qualquer coisa. Este ensaio parte do princípio de que há limites na interpretação de um filme. Partindo de textos de Umberto Eco e outros autores, que estudam o jogo interpretativo de textos literários, este ensaio pretende levar a discussão para o campo cinematográfico e estabelecer algumas destas fronteiras.

  10. Inauguration du C/R Forum (Belgique

    Directory of Open Access Journals (Sweden)

    2009-04-01

    Full Text Available Le 16 février dernier, la Vlaamse beroepsvereniging Conservatie en Restauratie Forum (C/R Forum a été constituée à l'initiative de 18 personnes du milieu de la conservation/restauration et du secteur de la protection du patrimoine. Etant donné que la conservation et la gestion du patrimoine culturel mobilier et immobilier de même que la formation et la recherche relèvent des communautés et des régions, la nécessité est apparue depuis un certain temps de créer une organisation Flamande au sei...

  11. Internal chlorination of Ni-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Berztiss, D.; Hennesen, K.; Grabke, H.J. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    1998-12-31

    In contrast to internal oxidation, sulfidation and carburization, very little information is available regarding internal chlorination, especially diffusion of chlorine in metallic alloys. This paper describes results of experiments on Ni-Cr alloys (<10 wt% Cr) exposed in an atmosphere containing radioactive HCl. The diffusion of chlorine in the alloy can be determined by measurement of residual {beta}-activity from the sample surface. Successively thin layers (0.5-10 {mu}m) of the alloy were removed by lapping and the surface activity was measured to obtain a depth profile. Both single and polycrystalline materials were tested. Through this work it should be determined if there is in fact solubility and diffusion of chlorine in Ni-based alloys as some authors have proposed or if the ingress of chlorine is mainly a grain boundary phenomenon. (orig.)

  12. Crítica de Libros.

    OpenAIRE

    Emilia García Castro; Beatriz Rodríguez Vega; Alfonso García-Ordás Álvarez; Tiburcio Angosto Saura

    1991-01-01

    Desarrollos contemporáneos recientes en psicoanálisis. Una evaluación crítica. Morris N. Eagle. Paidós 1988. Emilia García Castro Crónica de una investigación. La Evolución de la Terapia Familiar en la Obra de Mara· Selvini-Palazzoli. Compilador Matteo Selvini. Ed. Paidós, 1990. 363 páginas. 2000 pts. Beatriz Rodriguez Vega Mental health care delivery: Innovations, impediments and implementation. 1. Marks y R. Scott, Editores. Cambridge University Press. 1990. A. García-Ordás Introducción a l...

  13. Trace element geochemistry of CR chondrite metal

    CERN Document Server

    Jacquet, Emmanuel; Alard, Olivier; Kearsley, Anton T; Gounelle, Matthieu

    2015-01-01

    We report trace element analyses by laser ablation inductively coupled plasma mass spectrometry of metal grains from 9 different CR chondrites, distinguishing grains from chondrule interior ("interior grains"), chondrule surficial shells ("margin grains") and the matrix ("isolated grains"). Save for a few anomalous grains, Ni-normalized trace element patterns are similar for all three petrographical settings, with largely unfractionated refractory siderophile elements and depleted volatile Au, Cu, Ag, S. All types of grains are interpreted to derive from a common precursor approximated by the least melted, fine-grained objects in CR chondrites. This also excludes recondensation of metal vapor as the origin of the bulk of margin grains. The metal precursors presumably formed by incomplete condensation, with evidence for high-temperature isolation of refractory platinum-group-element (PGE)-rich condensates before mixing with lower temperature PGE-depleted condensates. The rounded shape of the Ni-rich, interior ...

  14. Cr Isotope Response to Ocean Anoxic Event 2

    Science.gov (United States)

    Holmden, C. E.; Jacobson, A. D.; Sageman, B. B.; Hurtgen, M.

    2015-12-01

    The element Cr offers a redox sensitive isotopic proxy with potential for tracing past oxygen levels in the oceans. We examine this potential in a marine carbonate section deposited during Cretaceous Ocean Anoxic Event 2 (OAE 2) in the Western Interior Seaway, Colorado. Redox changes are the main source of Cr isotope fractionation in Earth surface environments. Cr(VI), in the form of the chromate oxyanion, is the thermodynamically favoured species in oxygenated seawater. Reduction of Cr(VI) causes light isotopes to partition into Cr(III), which is reactive and susceptible to removal into marine sediment. Therefore, widespread ocean anoxia should correlate with positive shifts in seawater chromate Cr isotope values (δ53Cr), assuming that all Cr input fluxes remained constant during the event. We find instead that inferred seawater δ53Cr values decreased during OAE 2. The minima of the sedimentary δ53Cr excursion coincides with the peak interval of anomalously enriched concentrations of Cr and other trace metals of basaltic affinity attributed to eruption of the Caribbean Large Igneous Province (CLIP). We propose that an anoxic, hydrothermal plume enriched in Cr(III) with low δ53Cr values characteristic of igneous rocks moved from deep waters of the CLIP eruption site in the eastern Pacific into deep waters of the proto-North Atlantic through an oceanic gateway in the Central Americas. Once inside, metal-rich waters upwelled against the surrounding continental margins. CLIP volcanism delivered a submarine weathering flux of Cr to the oceans during OAE 2 that was large enough to mask the expected isotopic response of the ocean Cr cycle to increasing anoxia, particularly in the proto-North Atlantic Ocean.

  15. Complicidades de la crítica

    Directory of Open Access Journals (Sweden)

    Hernando Téllez

    1964-02-01

    Full Text Available La cuestión de saber qué le conviene más a una literatura, si el rigor o la benevolencia en la crítica de ella misma, no se plantea sino con relación a las literaturas pobres e incipientes, puesto que en ellas se considera excusable el balbuceo de las formas y la confusión de los valores.

  16. Application of a fast and efficient algorithm to detect areas with prerequisites for landslide in sensitive clays, Göta Älv, Sweden

    Science.gov (United States)

    Melchiorre, Caterina; Tryggvason, Ari

    2014-05-01

    In Sweden, landslide stability maps are based on the recognition of topographical and soil conditions. The topographical criterion is based on the ratio between height of the slope and its length. The calculation of this cross-sectional angle is straight forward in one dimension, but slightly more complicated in two dimensions and very computationally expensive in a GIS environment. We present an application of a fast and efficient computer algorithm based on slope and soil criteria in Göta Älv, southwest Sweden. The algorithm, compared to other software implementations of the cross-sectional angle criterion, guarantees a fast execution, the possibility to insert several threshold values of the cross-sectional angle and the use of information on bedrock elevation. As input maps we used a 1:50000 Quaternary soil map, a DEM at 2x2 m pixel resolution, and a bedrock elevation map. We used two sets of cross-sectional angle thresholds, the first one derived from stability calculation and the second one assessed through the relationship between QCSI (i.e., estimated value of the sensitivity) and the cross-sectional angle calculated from the landslide scar database. A comparison between the results of the algorithm using or not using the bedrock information was also performed. The produced maps were validated by using the landslide scar database and a hazard map. The results show that the use of bedrock information decreases the calculated areas with prerequisites for landslides, whereas not decreasing the performance of the algorithm. The maps produced by using the two different sets of cross-angle thresholds are very similar and show similar results in the validation. This means that it would be possible to extent this methodology in areas without geotechnical information by using less expensive data such as the QCSI. Moreover, the use of several cross-sectional angle thresholds is not possible in other software implementations available at the moment. This means that

  17. Aging in Co/Cr Superlattices

    Science.gov (United States)

    Mukherjee, T.; Pleimling, M.; Binek, Ch.

    2009-03-01

    Aging phenomena are observed in various systems brought into non-equilibrium and subsequently showing slow relaxation dynamics. Magnetic specimens with well defined interactions and dimensions can serve as model systems for universal aspects of aging. Magnetic thin films provide access to a wide range of microscopic parameters. Superlattice structures allow tuning the intra and inter-plane exchange and enable geometrical confinement of the spin fluctuations. We use Co/Cr thin film superlattices to study magnetic aging. The static and dynamic properties are affected via the Co and Cr film thicknesses. TC of the Co films is reduced from the bulk value by geometrical confinement. Non-ergodic behavior sets in at a tunable temperature T^* in a range of some 100K above zero. Cr provides antiferromagnetic coupling between the Co films. Non-equilibrium spin states are set via low field cooling in 5mT in-plane magnetic field to below T^*. Next various in-plane magnetic set fields of some 10-100 mT are applied and the sample is exposed to the latter for various waiting times tw, respectively. After removing the field, relaxation of the magnetization is recorded via longitudinal Kerr-magnetometry. The relaxation data are analyzed by scaling plots revealing universal aspects of aging. Financial support by Teledyne-Isco, NRI, and NSF through EPSCoR, Career DMR-0547887, and MRSEC.

  18. Collectivity of Cr Isotopes Approaching N = 40

    Science.gov (United States)

    Baugher, T.; Gade, A.; Bazin, D.; Cook, J. M.; Dinca, D.-C.; Glasmacher, T.; Mueller, W. F.; Ratkiewicz, A.; Weisshaar, D.; McDaniel, S.; Grinyer, G.; Walsh, K.; Janssens, R. V. F.; Carpenter, M. P.; Kondev, F. G.; Zhu, S.; Stefanescu, I.; Ricard-McCutchan, E.; Freeman, S.; Deacon, A.; Smith, J. F.; Kay, B.; Sharp, D.

    2011-10-01

    The reduced quadrupole transition probability, B(E2;0+ -->2+), provides a way to quantify low-lying collectivity in even-even nuclei. B(E2) values for 58 , 60 , 62Cr were extracted using intermediate-energy Coulomb excitation at the NSCL. Cocktail beams containing 58 , 60 , 62Cr were produced in-flight and guided onto a high- Z target. De-excitation gamma-rays tagging the inelastic process were detected in coincidence with the scattered particles using the high-purity germanium array SeGA and the S800 spectrograph. The measurement allowed the B(E2) values of 60,62Cr to be extracted for the first time. Results are compared to large-scale shell-model calculations using a recent effective interaction developed for this region. This work was funded by the NSF under contract PHY-0606007; by the US DOE, ONP, under contracts DE- AC02-06CH11357 and DE-FG02-08ER41556 and by the UK Science and Technology Facilities Council (STFC).

  19. Advance directives: prerequisites and usefulness.

    Science.gov (United States)

    van Asselt, D

    2006-10-01

    Advance directives allow competent persons to extend their right of self-determination into the future, by recording choices that are intended to influence their future care should they become unable to make choices. They are considered tools to facilitate end-of-life decision making. Advance directives are a form of anticipatory decision-making. This article will focus on instruction directives against a certain treatment, so-called advance refusals. The most important legal requirement is the acknowledgement of patient autonomy. This condition is met in all European countries. The legal uncertainties surrounding advance refusals are focused on practical modalities rather than on the validity of the general principle. According to leading ethics the underlying moral rule of advanced directives is that all truly autonomous refusals of treatment must be respected, no matter what the consequences. Physicians find it hard to adhere to the wishes and choices of patients as expressed in directives. They find the text ambiguous. Another weakness is that directives give little information about what in the patient's view constitutes a good quality of life. Some health professionals lack the willingness to step outside their own value systems and fully embrace that of the patient. Empathic skills are required. Very few persons create an advance directive. Furthermore, of the created directives only some are accessible when patients are admitted to hospital. However, when directives are available they usually influence medical treatment decisions.

  20. Prerequisite Testing for Infertility Treatment

    Science.gov (United States)

    ... Party Reproduction A Patient's Guide to Assisted Reproductive Technology Frequently Asked Questions History of IVF PROFESSIONALS & PROVIDERS Join SART Research Publications The SART Executive Council ASRM Ethics Reports ASRM Practice Guidelines Career Opportunities IVF SUCCESS ...

  1. [Irradiation in stereotactic conditions: prerequisites].

    Science.gov (United States)

    Maingon, P; Lisbona, A

    2014-10-01

    Indications of treatment by stereotactic body radiotherapy are dramatically increasing due to new potential indications. The conditions associated with the treatment delivery are multiple. The first step of the process is crucial. It is related to the validation of the indication proposed during the multidisciplinary meeting as regard the evidence-based proof of the concept. These emerging techniques mainly extracranial stereotactic body irradiation do not benefit from long-term evaluation in terms of efficiency as well as normal tissue late toxicities. Priority should be given to prospective independent clinical trials, validated by an independent scientific committee, performed under a relevant and well dedicated multicentric quality assurance program aiming to improve knowledge and selection of indications. The SFRO is still working with others professionals on the definition of the conditions for the implementation of such treatments and actively collaborates with the authorities to define the appropriate conditions to preserve the quality of the treatment delivery under these specific conditions. Copyright © 2014 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

  2. GRAMMATICAL PREREQUISITES TO PHONOLOGICAL CHANGE?*

    African Journals Online (AJOL)

    problematic. Following some general remarks on the nature of the problem .... When reading the contemporary literature on language change, one is struck by ... that the vowel of the definite plural morpheme -en in Swedish neutral nouns like ...

  3. Photon emission produced by Kr+ ions bombardment of Cr and Cr2O3 targets

    Science.gov (United States)

    Boujlaidi, A. El; Hammoum, K.; Jadoual, L.; Jourdani, R.; Ait El Fqih, M.; Aouchiche, H.; Kaddouri, A.

    2015-01-01

    The sputter induced photon spectroscopy technique was used to study the luminescence spectra of the species sputtered from chromium powder and its oxide Cr2O3, during 5 keV Kr+ ions bombardment in vacuum better than 10-7 torr. The optical spectra recorded between 350 and 470 nm exhibit discrete lines which are attributed to neutral excited atoms of chromium (Cr I lines). The experiments are also performed under 10-5 torr ultra pure oxygen partial pressure. The results demonstrate that the measured intensities of the emitted photons are always higher in the presence of oxygen and even higher than those obtained for Cr2O3 target. In the presence of oxygen vapor we assume that an oxide film is formed on the chromium surface which is responsible of the increase of photon emission. This variation in the intensities is correctly explained in the model of electron transfer processes between the excited sputtered atom and the bombarded surface. This model suggests that the structure formed on the Cr surface in the case of oxygenated chromium is closer to that of Cr2O3 oxide.

  4. Metal organic framework MIL-101(Cr) for dehydration reactions

    Indian Academy of Sciences (India)

    M Suresh; B David Raju; K S Rama Rao; K Raveendranath Reddy; M Lakshmi Kantam; Pavuluri Srinivasu

    2014-03-01

    Porous chromium terephthalate MIL-101 (Cr-MIL-101) has been prepared by direct method under hydrothermal conditions and characterized using X-ray diffraction, N2 sorption, TGA and FT-IR. The nitrogen adsorption-desorption isotherm shows that the Cr-MIL-101 possesses BET specific surface area of 2563 m2/g. Catalytic performance of Cr-MIL-101 in the dehydration of 1,4-butanediol and 1-phenylethanol is assessed under vapour phase conditions in the temperature range of 513-533 K and time on stream (TOS) at 513 K. Cr-MIL-101 demonstrates superior catalytic activity with conversion of 95% of 1-phenylethanol. Moreover, high surface area and nanocages with coordinated unsaturated sites of Cr-MIL-101 have allowed us to attain higher dehydrated products selectivity than Cr-supported activated carbon (Cr/AC), amberlyst-15 and HZSM-5 catalysts.

  5. Should Research Thesis be a Prerequisite for Doctor of Medicine Degree? A Cross-sectional Study at Jordan University of Science and Technology

    Directory of Open Access Journals (Sweden)

    Aisha Gharaibeh

    2014-02-01

    Full Text Available Background: University based research is an integral part of many prestigious medical schools worldwide. The benefits of student-conducted research have long been highlighted in the literature. This article aims to identify the insights of medical students concerning research training, including perceived hurdles in the way of conducting research, and the utility of a research thesis in acquiring a Doctor of Medicine degree.Methods: A total of 808 medical students at Jordan University of Science and Technology were selected by random sampling with a confidence level of 95%. A survey was constructed by a group of students through literature review and group discussions. The survey utilized polar and Likert scale questions to collect data from the students. Statistical inferences were then obtained through analysis of means and one sample t-test of the hypothesis.Results: A total of 687 students filled out the survey (85%. Analysis shows that respondents have a strong and positive attitude towards research. The respondents with past research experience constituted 14.3% of those surveyed. Those respondents identified the barriers faced by them during their experience. The students showed high degree of agreement that a research thesis should be a prerequisite for graduation with statistical significance of p-value ≤0.05.Conclusion: Modifying the curriculum to include research methodology is recommended, and developing it to incorporate a thesis as a requirement for graduation may be advised upon further review.

  6. The reactive oxygen species network pathways: an essential prerequisite for perception of pathogen attack and the acquired disease resistance in plants

    Indian Academy of Sciences (India)

    Simeon O Kotchoni; Emma W Gachomo

    2006-09-01

    Availability of complete Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) genome sequences, together with molecular recourses of functional genomics and proteomics have revolutionized our understanding of reactive oxygen species (ROS) signalling network mediating disease resistance in plants. So far, ROS have been associated with aging, cellular and molecular alteration in animal and plant cells. Recently, concluding evidences suggest that ROS network is essential to induce disease resistance and even to mediate resistance to multiple stresses in plants. ROS are obligatory by-products emerging as a result of normal metabolic reactions. They have the potential to be both beneficial and harmful to cellular metabolism. Their dual effects on metabolic reactions are dosage specific. In this review we focus our attention on cellular ROS level to trigger beneficial effects on plant cells responding to pathogen attack. By exploring the research related contributions coupled with data of targeted gene disruption, and RNA interference approaches, we show here that ROS are ubiquitous molecules of redox-pathways that play a crucial role in plant defence mechanism. The molecular prerequisites of ROS network to activate plant defence system in response to pathogen infections are here underlined. Bioinformatic tools are now available to scientists for high throughput analysis of cellular metabolisms. These tools are used to illustrate crucial ROS-related genes that are involved in the defence mechanism of plants. The review describes also the emerging findings of ROS network pathways to modulate multiple stress resistance in plants.

  7. On the trail of Vikings with polarized skylight: experimental study of the atmospheric optical prerequisites allowing polarimetric navigation by Viking seafarers.

    Science.gov (United States)

    Horváth, Gábor; Barta, András; Pomozi, István; Suhai, Bence; Hegedüs, Ramón; Akesson, Susanne; Meyer-Rochow, Benno; Wehner, Rüdiger

    2011-03-12

    Between AD 900 and AD 1200 Vikings, being able to navigate skillfully across the open sea, were the dominant seafarers of the North Atlantic. When the Sun was shining, geographical north could be determined with a special sundial. However, how the Vikings could have navigated in cloudy or foggy situations, when the Sun's disc was unusable, is still not fully known. A hypothesis was formulated in 1967, which suggested that under foggy or cloudy conditions, Vikings might have been able to determine the azimuth direction of the Sun with the help of skylight polarization, just like some insects. This hypothesis has been widely accepted and is regularly cited by researchers, even though an experimental basis, so far, has not been forthcoming. According to this theory, the Vikings could have determined the direction of the skylight polarization with the help of an enigmatic birefringent crystal, functioning as a linearly polarizing filter. Such a crystal is referred to as 'sunstone' in one of the Viking's sagas, but its exact nature is unknown. Although accepted by many, the hypothesis of polarimetric navigation by Vikings also has numerous sceptics. In this paper, we summarize the results of our own celestial polarization measurements and psychophysical laboratory experiments, in which we studied the atmospheric optical prerequisites of possible sky-polarimetric navigation in Tunisia, Finland, Hungary and the high Arctic.

  8. Adaptació d’una bateria per a l’avaluació de prerequisits per a l’aprenentatge d’Estadística en Psicologia

    Directory of Open Access Journals (Sweden)

    Joan Guàrdia-Olmos

    2012-07-01

    Full Text Available Les recerques recents sobre docència universitària en estadística s’han centrat en identificar les principals variables que afecten al rendiment acadèmic. L’objectiu d’aquest estudi és analitzar les propietats psicomètriques de quatre qüestionaris (SAS, SATS, MSES-R, PMP disposats en una bateria de prerequisits per a l’aprenentatge de l’estadística i, per tant, potencials predictors del rendiment.Mètode: La bateria es va administrar a una mostra de 96 estudiants del Grau en Psicologia de la Universitat de Barcelona durant el curs acadèmic 2010-2011 en l’assignatura de Tècniques de Recerca.Resultats: Totes les escales van mostrar alts valors en els coeficients de consistència interna. En relació a la validesa, es van trobar correlacions significatives en sentit negatiu entre els factors teòrics del SAS i del SATS. Les puntuacions d’autoeficàcia davant els problemes matemàtics estaven fortament relacionades amb el rendiment en matemàtiques. Les anàlisis factorials van mostrar una solució de cinc factors per al SAS i una solució unifactorial per al MSES-R.

  9. Identification of the key bitter compounds in our daily diet is a prerequisite for the understanding of the hTAS2R gene polymorphisms affecting food choice.

    Science.gov (United States)

    Hofmann, Thomas

    2009-07-01

    In order to decode genetic variations affecting food choice and to determine whether to accept or to reject certain food products, it is a necessary prerequisite to deorphanize the hTAS2R/ligand pairs using the key bitter compounds in foods as stimuli rather than doing this either by using artificial molcules, to which the normal consumer had never been exposed, or by using food-born molecules which do not at all contribute to the overall bitterness. Therefore, the chemical structure of the most active bitter molecules in foods needs to be unequivocally determined in order to be sure that hTAS2R polymorphisms are related to the key molecules which really contribute to the overall bitterness perception of food products. As most studies focused primarily on quantitatively predominating compounds, rather than selecting the target compounds to be identified with regard to taste-activity, it seems that yet unknown components play a key role in evoking the bitter taste of food products. Driven by the need to discover the key players inducing the food taste, the research area "sensomics" made tremendous efforts in recent years to map the sensometabolome and to identify the most intense taste-active metabolites in fresh and processed foods. The present article summarizes recent studies on the identification of orphan key bitter stimuli in fresh, fermented, and thermally processed foods using carrots, cheese, and roasted coffee as examples.

  10. Attitudes and Prerequisites for the Establishment of an Integrated Cultural Identity within Romanian-Bulgarian Cross-Border Region along the Danube River

    Directory of Open Access Journals (Sweden)

    Juliana Popova

    2013-08-01

    Full Text Available Objectives: On the basis of the results from an empirical study this research aims at exploration of the prerequisites for the establishment of an integrated cultural identity within Romanian-Bulgarian Cross-Border Region along the Danube River (RBCBR. Prior Work: The paper is trying to prove the necessity of identity re-negotiation process within RBCBR. The theoretical background of the research is related to some of the most topical considerations in this scientific field. Approach: The research uses an interdisciplinary approach and combines the perspectives of regional studies, cross-cultural psychology and intercultural communication. A representative survey is the main instrument of the research. Results: Among the citizens of the RBCBR there exist favourable attitudes towards closer relations with their neighbours which can serve as a key element of the identity re-negotiation process within the region. Implications: The research results can be used by policy makers and regional authorities in the process of establishment of a new policy for territorial cooperation as well as by researchers in further development of this topic area. Value: the importance of the research is in its new approach towards the establishment of integrated regional identity as well as in the comparison of the Romanian and Bulgarian attitudes towards cooperation in the neighbourhood area.

  11. Single-Tube Reaction Using Perfluorocarbons: A Prerequisite Step Leading to the Whole-Slide In Situ Technique on Histopathological Slides.

    Directory of Open Access Journals (Sweden)

    Yi-Chang Chen

    Full Text Available Developing a robust, novel method for performing multiple reactions in a single tube is not only time- and cost-saving but also critical for future high-throughput whole-slide in situ techniques on diseased tissues. In this study, we introduce the use of perfluorocarbons and compound-coated magnetic particles to create pseudochambers in a single tube, allowing different reactions to be performed in different phases. Perfluorocarbons also serve as cell lysis buffer and polymerase chain reaction (PCR buffer owing to their highly penetrating, repellent and emulsifiable properties. Using this method, nucleic acids can be isolated and purified from various sample types and sizes, followed by PCR, real-time PCR, or multiplex PCR in the same tube. No incubation or enzyme digesting time is needed and the risk of cross-contamination is reduced. Tests can be performed in microemulsions (water-in-oil droplets containing sequence-specific captures and probes for further high-throughput detection. We present a simple, quick, and robust procedure as a prerequisite step to future high-throughput in situ techniques.

  12. Procurement of V-Cr-Ti alloys to study minor variations on V-4Cr-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Grossbeck, M.L. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    The alloys V-6Cr-3Ti, V-4Cr-4Ti-Si, V-6Cr-6Ti, and V-3Cr-3Ti, were prepared by Teledyne Wah Chang Albany Corp. in 1994. Plate and sheet ranging from 0.76 mm to 6.25 mm with residual material being left in 12--20 mm thick bar were fabricated. Although the heats were prepared on a pilot plant scale using different equipment, an effort was made to keep the processing as close to Wah Chang Heat 832665, the reference fusion heat of V-4Cr-4Ti, as possible.

  13. Synthesis and chemistry of chromium in CrAPO-5 molecular sieves

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    1994-01-01

    CrAPO-5 molecular sieves were synthesized hydrothermally starting with different Cr precursors and Cr and template contents. The behavior of Cr was investigated spectroscopically by diffuse reflectance spectroscopy (d.r.s.) and electron spin resonance (e.s.r.). In the gels, Cr 3+ and Cr 8+ are prese

  14. Optimization Of Multi-Module CrN/CrCN Coatings

    Directory of Open Access Journals (Sweden)

    Szparaga Ł.

    2015-06-01

    Full Text Available In the paper was proposed optimization procedure supporting the prototyping of the geometry of multi-module CrN/CrCN coatings, deposited on substrates from 42CrMo4 steel, in respect of mechanical properties. Adopted decision criteria were the functions of the state of internal stress and strain in the coating and substrate, caused by external mechanical loads. Using developed optimization procedure the set of optimal solutions (Pareto-optimal solutions of coatings geometry parameters, due to the adopted decision criteria was obtained. For the purposes of analysis of obtained Pareto-optimal solutions, their mutual distance in the space of criteria and decision variables were calculated, which allowed to group solutions in the classes. Also analyzed the number of direct neighbors of Pareto-optimal solutions for the purposes of assessing the stability of solutions.

  15. Creep behavior of plasma sprayed NiCr and NiCrAl coating-based systems

    Institute of Scientific and Technical Information of China (English)

    Xiancheng ZHANG; Changjun LIU; Fuzhen XUAN; Zhengdong WANG; Shan-Tung TU

    2011-01-01

    The creep behavior of the plasma sprayed NiCr and NiCrAl coating/Nickel alloy 690substrate systems at 1033 K was investigated. Results showed that there was almost no difference in the creep lives between the NiCr and NiCrAl coated specimens at a given stress level, since the contents of Cr used in the NiCr and NiCrAl powders are almost same. The relationship between the minimum creep rate and the applied stress followed the well-known Norton's power law, εmin=Aσn, with the values of A=2.66× 10-16 Mpa-n.h-1 and n=6.48. The relation between the applied stress and time to rupture of the coated specimens can be estimated by using Larson-Miller equation. The θ projection method can be used to accurately characterize the creep behavior of the coated specimens.

  16. Atomistic investigation of Cr influence on primary radiation damage in Fe-12 at.% Cr grain boundaries

    Science.gov (United States)

    Esfandiarpour, A.; Feghhi, S. A. H.; Arjhangmehr, A.

    2016-08-01

    In this paper, we investigate the influence of Cr on the primary radiation damage in Fe-12 at.% Cr with different atomic grain boundaries (GBs). Four different GB structures, two twists and two symmetric tilt boundaries are selected as the model structures. The primary radiation damage near each GB in α-Fe and Fe-12 at.% Cr is simulated using Molecular Dynamics for 9 keV primary knock-on atoms with velocity vectors perpendicular to the GB plane. In agreement with previous works, the results indicate that the atomic GBs are biased toward interstitials and due to the reduction of ‘in-cascade’ interstitial-vacancy annihilation rates, vacancies accumulate in the bulk grains. The minimum defect production occurs when the overlap between cascade center and GB plane is maximum; in contrast, the number of residual defects in the bulk (vacancies and interstitials) increases when the overlap decreases. Moreover, we find that the presence of Cr hardly affects the number of residual defects in the grain interiors, and causes a Cr-enrichment in the surviving self-interstitial atoms in bulk during relaxation of the primary cascades—also in agreement with previous studies. Further, in order to study the effect of 12 at.% Cr on the energetic and kinetic properties of vacancies near the atomic GBs, we calculate formation energies and diffusion barriers of defects using Molecular Static and climbing-Nudged Elastic Band methods. The results reveal that the vacancies energetically and kinetically tend to form and cluster around the GB plane due to the substantial reduction of their formation energies and migration barriers in layers close to the GB center and are immobile on the simulated time frame (~ps).

  17. Heat Treatment of Cr- and Cr-V ledeburitic tool steels

    Directory of Open Access Journals (Sweden)

    Peter Jurči

    2014-11-01

    Full Text Available Cr- and Cr-V ledeburitic cold work tool steels belong to the most important tool materials for large series manufacturing. To enable high production stability, the tools must be heat treated before use. This overview paper brings a comprehensive study on the heat treatment of these materials, starting from the soft annealing and finishing with the tempering. Also, it describes the impact of any step of the heat treatment on the most important structural and mechanical characteristics, like the hardness, the toughness and the wear resistance. The widely used AIS D2- steel (conventionally manufactured and Vanadis 6 (PM are used as examples in most cases.

  18. L'univers créativité cosmique et créativité artistique

    CERN Document Server

    Reeves, Hubert; Champion, Claire

    2016-01-01

    Avec le talent de vulgarisateur qu'on lui connaît, Hubert Reeves explique, en faisant d'habiles parallèles avec la créativité humaine, ce que l'on sait aujourd'hui de la création de l'Univers. Avec ses mots et ses idées simples, épurées comme des haïkus, Hubert Reeves arrive à faire comprendre l'infiniment complexe, tout en amenant ses lecteurs au bord du gouffre métaphysique.

  19. Bainite Morphology in Two Experimental Mo-Cr and Mo-Cr-V-Ti Steels

    Directory of Open Access Journals (Sweden)

    Ławrynowicz Z.

    2014-10-01

    Full Text Available The paper presents an investigation of the bainite morphology in two experimental Mo-Cr and Mo-Cr-V-Ti steels using TEM, high speed dilatometry backed by thermodynamic analysis. The microstructure was investigated using metallography and TEM method. After austenitisation at 1200oC followed by bainitic reaction in upper and lower temperatures of isothetmal transformation the bainite was in the form of classical sheaves. The amont, distribution and morphology of retained austenite and bainitic ferrite depend on prior austenitisation and isothermal transformation temperatures within the bainitic range.

  20. Speciated isotope dilution analysis of Cr(III) and Cr(VI) in water by ICP-DRC-MS.

    Science.gov (United States)

    Ma, H-L; Tanner, P A

    2008-10-19

    An isotope dilution method has been developed for the speciation analysis of chromium in natural waters which accounts for species interconversions without the requirement of a separation instrument connected to the mass spectrometer. The method involves (i) in-situ spiking of the sample with isotopically enriched chromium species; (ii) separation of chromium species by precipitation with iron hydroxide; (iii) careful measurement of isotope ratios using an inductively coupled plasma mass spectrometer (ICP-MS) with a dynamic reaction cell (DRC) to remove isobaric polyatomic interferences. The method detection limits are 0.4 microg L(-1) for Cr(III) and 0.04 microg L(-1) for Cr(VI). The method is demonstrated for the speciation of Cr(III) and Cr(VI) in local nullah and synthetically spiked water samples. The percentage of conversion from Cr(III) to Cr(VI) increased from 5.9% to 9.3% with increase of the concentration of Cr(VI) and Cr(III) from 1 to 100 microg L(-1), while the reverse conversion from Cr(VI) to Cr(III) was observed within a range between 0.9% and 1.9%. The equilibrium constant for the conversion was found to be independent of the initial concentrations of Cr(III) and Cr(VI) and in the range of 1.0 (at pH 3) to 1.8 (at pH 10). The precision of the method is better than that of the DPC method for Cr(VI) analysis, with the added bonuses of freedom from interferences and simultaneous Cr(III) determination.

  1. Crystal structure and magnetic properties of Li,Cr-containing molybdates Li 3Cr(MoO 4) 3, LiCr(MoO 4) 2 and Li 1.8Cr 1.2(MoO 4) 3

    Science.gov (United States)

    Sarapulova, A.; Mikhailova, D.; Senyshyn, A.; Ehrenberg, H.

    2009-12-01

    Single crystals of LiCr(MoO 4) 2, Li 3Cr(MoO 4) 3 and Li 1.8Cr 1.2(MoO 4) 3 were grown by a flux method during the phase study of the Li 2MoO 4-Cr 2(MoO 4) 3 system at 1023 K. LiCr(MoO 4) 2 and Li 3Cr(MoO 4) 3 single phases were synthesized by solid-state reactions. Li 3Cr(MoO 4) 3 adopts the same structure type as Li 3In(MoO 4) 3 despite the difference in ionic radii of Cr 3+ and In 3+ for octahedral coordination. Li 3Cr(MoO 4) 3 is paramagnetic down to 7 K and shows a weak ferromagnetic component below this temperature. LiCr(MoO 4) 2 is isostructural with LiAl(MoO 4) 2 and orders antiferromagnetically below 20 K. The magnetic structure of LiCr(MoO 4) 2 was determined from low-temperature neutron diffraction and is based on the propagation vektor k⇒=({1}/{2},{1}/{2},0). The ordered magnetic moments were refined to 2.3(1) μ B per Cr-ion with an easy axis close to the [1 1 1¯] direction. A magnetic moment of 4.37(3) μ B per Cr-ion was calculated from the Curie constant for the paramagnetic region. The crystal structures of the hitherto unknown Li 1.8Cr 1.2(MoO 4) 3 and LiCr(MoO 4) 2 are compared and reveal a high degree of similarity: In both structures MoO 4-tetrahedra are isolated from each other and connected with CrO 6 and LiO 5 via corners. In both modifications there are Cr 2O 10 fragments of edge-sharing CrO 6-octahedra.

  2. Heterogeneity of Cr in Mytilus edulis: Implications for the Cr isotope system as a paleo-redox proxy

    Science.gov (United States)

    Bruggmann, Sylvie; Klaebe, Robert; Frei, Robert

    2017-04-01

    Changes in 53Cr/52Cr (δ53Cr) values recorded by biogenic carbonates are emerging as a proxy for variations in the redox state of the Earth's oceans and atmosphere (e.g. [1], [2]). We investigate the ability of modern carbonate shells (Mytilus edulis) to record the δ53Cr composition of ambient seawater in order to assess their utility as a paleo-redox proxy. Samples of cultivated M. edulis from the Kiel Fjord, Germany, were analyzed for their δ53Cr composition and Cr concentrations [Cr] using TIMS. To disentangle the pathway of Cr into the carbonate shell, a series of step-digestions of their organic outer sheaths (periostraca) and their intra-layer composition were performed. Bulk analyses of specimens with intact periostraca returned 16 to 34 ppb Cr with δ53Cr values ranging from 0.28 to 0.65 ± 0.1 (2SE) and thus fall within the range of surface seawater from the Baltic Sea (0.3 - 0.6 \\permil [3]). Partial removal of periostraca resulted in lower [Cr] (5 to 17 ppb) and δ53Cr values (-0.05 ± 0.15 \\permil). These results show a positive correlation between the amount of organic matter present in a sample and both [Cr] and δ53Cr (n = 9). With nearly complete removal of periostraca, the remaining [Cr] is significantly lower (less than 5 ppb) and can only be accessed by incineration of the carbonate shell. The correlation between [Cr], δ53Cr and the amount of periostracum present in bulk samples indicates that a significant proportion of preserved Cr may be associated with the organic outer sheath. The Cr endmember accessed after incineration is less likely associated with the carbonate crystal lattice. Instead, the δ53Cr values obtained after incineration are similar to those reported from terrestrial rocks, suggesting the influence of detrital particles. Alternatively, Cr may be reduced and subsequently re-oxidized during the mineralization of biogenic carbonates [4]. Seasonal changes in primary productivity in seawater may further influence the shell

  3. Cr(VI) uptake mechanism of Bacillus cereus.

    Science.gov (United States)

    Chen, Zhi; Huang, Zhipeng; Cheng, Yangjian; Pan, Danmei; Pan, Xiaohong; Yu, Meijuan; Pan, Zhiyun; Lin, Zhang; Guan, Xiong; Wu, Ziyu

    2012-04-01

    In this study, we investigated the Cr(VI) uptake mechanism in an indigenous Cr(VI)-tolerant bacterial strain -Bacillus cereus through batch and microscopic experiments. We found that both the cells and the supernatant collected from B. cereus cultivation could reduce Cr(VI). The valence state analysis revealed the complete transformation from Cr(VI) into Cr(III) by living B. cereus. Further X-ray absorption fine structure and Fourier transform infrared analyses showed that the reduced Cr(III) was coordinated with carboxyl and amido functional groups from either the cells or supernatant. Scanning electron microscopy and atomic force microscopy observation showed that noticeable Cr(III) precipitates were accumulated on bacterial surfaces. However, Cr(III) could also be detected in bacterial inner portions by using transmission electron microscopy thin section analysis coupled with energy dispersive X-ray spectroscopy. Through quantitative analysis of chromium distribution, we determined the binding ratio of Cr(III) in supernatant, cell debris and cytoplasm as 22%, 54% and 24%, respectively. Finally, we further discussed the role of bacterium-origin soluble organic molecules to the remediation of Cr(VI) pollutants.

  4. Synthesis and characterization of Cu-Cr-O nanocomposites

    Institute of Scientific and Technical Information of China (English)

    LI Wei; CHENG Hua

    2007-01-01

    Cu-Cr-O nanocomposites that can be used as additives for the catalytic combustion of AP(ammonium perchlorate)-based solid-state propellants were synthesized via a citric acid(CA) complexing approach. Techniques of TG-DTA, XRD as well as TEM were employed to characterize the thermal decomposition procedure, crystal phase, micro-structural morphologies and grain size of the as-synthesized materials respectively. The results show that well-crystallized Cu-Cr-O nanocomposites can be produced after the CA-Cu-Cr precursors are calcined at 500 ℃ for 3 h. Phase composition of the as-obtained Cu-Cr-O nanocomposites depends on the molar ratio of Cu to Cr in the starting reactants. Addition of the as-synthesized Cu-Cr-O nanocomposites as catalysts enhances the burning rate as well as lowers the pressure exponent of the AP-based solid-state propellants considerably. Noticeably, catalyst with a Cu/Cr molar ratio of 0.7 exhibits promising catalytic activity with high burning rate and low pressure exponent at all pressures, due to the effective phase interaction between the spinel CuCr2O4 and delafossite CuCrO2 contained in the as-synthesized Cu-Cr-O nanocomposites.

  5. Electrodeposition of Ni-Cr alloy on aluminum substrate

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Ni-Cr alloys with mass fraction of 1.4%-23.9 %Cr, 76.1%-98.6 % Ni, and hardness of 70.5-80.5HR were electrodeposited on aluminium substrate from the trivalent chromium sulphate-chloride solution using citric acid as complexing agent. The aluminium was pretreated by means of degreasing and eroding, polishing and twice chemicai immersion of zinc. The effects of electrodeposition parameters such as current density, temperature, pH value and bath concentration on the composition and hardness of deposits were investigated. The results show that the Cr content increases with the increase of current density and the decrease of temperature, and that it increases with the increase of pH value to a maximum and then decreases. The increase of Cr content leads to the increase of hardness of the Ni-Cr layers. The deposits with high Cr content are of good corrosion resistance. Good adherence of Ni-Cr deposits to aluminium substrate is obtained. The Ni-Cr alloys are the Ni-Cr solid solution with fcc crystalline structure. The Ni-Cr alloy deposits are fine, bright and smooth and compact.

  6. Synthesis, Microstructure, and Property of Cr2AlC

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Cr2AlC is an unusual layered ternary ceramic that combines the merits of both metals and ceramics. The salient properties of Cr2AlC are strongly related to its bonding characteristics and microstructures. Synthesis,microstructure, and property of Cr2AlC are reviewed in this paper. First, theoretical calculations and physical properties are introduced. Then, the processing of Cr2AlC ceramic in both bulk form and thin films and their basic mechanical properties are summarized. Atomic-scale characterizations of Cr2AlC, as well as the microstructural relationships among Cr2AlC, Al8Cr5, and AlCr2 were achieved using a series of transmission electron microscopy (TEM) techniques. Moreover, high-temperature oxidation and hot corrosion behaviors of Cr2AlC were investigated by means of thermogravimetric analysis, X-ray diffraction, Raman spectroscopy,scanning electron microscopy, and TEM. Mechanism of the excellent high-temperature corrosion resistance of Cr2AlC is discussed based on systematic microstructural analyses. Finally, concise conclusions are drawn.

  7. Ekspresi protein pada mikroorganisme resisten Cr dengan metode elektroforesis

    Directory of Open Access Journals (Sweden)

    UMI FATMAWATI

    2009-05-01

    Full Text Available Fatmawati U, Suranto, Sajidan. 2009. Ekspresi protein pada mikroorganisme resistenCr dengan metode elektroforesis. Bioteknologi 6: 40-48. Krom heksavalen (Cr(VI dikenal sebagai logam berat beracun, sehingga perlu direduksi menjadi Cr(III yang lebih rendah toksisitasnya. Pseudomonas aeruginosa, Pseudomonas putida, Klebsiella pneumoniae, Pantoea sp. dan Saccharomyces cerevisiae adalah mikroorganisme resisten dan mampu mereduksi Cr(VI. Tujuan penelitian ini adalah mengetahui kemampuan mikroorganisme dalam mengurangi Cr(VI dan mengetahui pola pita protein antara mikroorganisme resisten Cr(VI dan mikroorganisme tidak resisten yang diinokulasi pada medium kaldu LB. SDS-PAGE digunakan untuk mengetahui ekspresi protein, sementara konsentrasi Cr(VI diidentifikasi dengan metode 1,5 difenilkarbazid. Data kuantitatif dianalisis dengan ANAVA dua faktorial dilanjutkan dengan uji jarak berganda Duncan pada taraf 1%. Data kualitatif yaitu ekspresi protein dianalisis dengan mobilitas relatif (Rf. Hasil penelitian menunjukkan bahwa kemampuan mikroorganisme dalam mereduksi Cr(VI pada konsentrasi awal 0.5 ppm, 1 ppm, 5 ppm dan 10 ppm berbeda-beda, persentase rata- rata kemampuan masing-masing mikroorganisme dalam mereduksi Cr(VI adalah: P. putida (65% > S. cerevisiae (64,45% > P. aeruginosa (60,73% > Pantoea sp. (50,22% > K. pneumoniae (47,82% > tanpa mikroorganisme (34,25%. Penambahan mikroorganisme secara nyata mempengaruhi reduksi Cr(VI. SDS-PAGE menunjukkan bahwa ekspresi protein antara mikroorganisme resisten dan tidak resisten tidak berbeda, tetapi mikroorganisme resisten memiliki lebih banyak protein (pita protein lebih tebal.

  8. Electrochemical behavior of Ti-Cr alloys in artificial saliva

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, H.-C.; Wu, S.-C. [Department of Dental Laboratory Technology, Central Taiwan University of Science and Technology, Taiwan (China); Institute of Biomedical Engineering and Material Science, Central Taiwan University of Science and Technology, Taiwan (China); Wang, C.-F. [Institute of Biomedical Engineering and Material Science, Central Taiwan University of Science and Technology, Taiwan (China); Ho, W.-F., E-mail: fujii@mail.dyu.edu.t [Department of Materials Science and Engineering, Da-Yeh University, Taiwan (China)

    2009-11-13

    In this study, the corrosion behavior of commercially pure titanium (c.p. Ti), Ti-6Al-4V and five new experimental Ti-Cr alloys was evaluated through open-circuit potential (OCP) and potentiodynamic polarization measurement in an artificial saliva containing fluoride. Electron spectroscopy for chemical analysis (ESCA) was used to characterize the composition of the passive films on the alloy after potentiodynamic polarization measurement. It was found that in standard artificial saliva the OCP increases with higher Cr content in Ti-Cr alloys. In 0.5% NaF artificial saliva, the OCP decreases with decreasing Cr in Ti-Cr alloys, and all but Ti-5Cr remain consistently higher than those of c.p Ti and Ti-6Al-4V. Linear polarization results show that artificial saliva and artificial saliva containing 0.5% NaF result in different corrosion behavior in Ti-Cr alloys, c.p.Ti and Ti-6Al-4V. The Ti-Cr alloys had greater resistance to corrosion in the fluoride-containing artificial saliva than c.p. Ti and Ti-6Al-4V, respectively. ESCA results verify that after potentiodynamic polarization a passive film consisting of TiO{sub 2} and Cr{sub 2}O{sub 3} forms on the surface of Ti-Cr alloys. These experimental results show that the electrochemical corrosion behavior of Ti-Cr alloys in artificial saliva containing 0.5% NaF can be improved by increasing Cr content. This further indicates that Ti-Cr alloys could successfully be used for crown, bridge, and metal-ceramic restorations.

  9. Intrinsic noncollinear magnetization in Fe/Cr superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Yartseva, N.S., E-mail: yartseva@imp.uran.ru [Institute of Metal Physics, UD of RAS, Ekaterinburg 620990 (Russian Federation); Yartsev, S.V. [ZAO NPO “Spektr”, 14 Berezovskiy 623700 (Russian Federation); Demangeat, C. [UFR de Physique et d’Ingéniérie, Université de Strasbourg, 3 rue de l’Université, 67000 Strasbourg (France)

    2014-12-15

    Magnetic moments distribution in Fe{sub 3}Cr{sub n} superlattice series with fixed middle Fe monolayer and number of Cr monolayers (MLs) n from 1 to 45 is computed in the framework of collinear and noncollinear Periodic Anderson model. The superlattices are composed of layers in (0 0 1) and (1 1 0) plane with ideal interface. The total energy shows that noncollinear orientation of the magnetic moments remains the ground state for all superlattices with Cr thickness above 5 MLs. Distribution of the magnetic moments for Fe/Cr(0 0 1) superlattices depends on parity of the Cr MLs. For odd numbers Cr magnetic moments are canted and symmetrically distributed between the neighboring Fe slabs. The values of Cr moments are enhanced at the interface and weakened to the bulk in the middle. For even numbers of Cr MLs quasi-helicoidal magnetic moments distribution consisting of two interleaved spirals is found. The moments are screwing sequentially from Fe/Cr interface to perpendicular orientation, keeping the angles and moments for some successive MLs, and then continue screwing towards the next interface. In Fe/Cr(1 1 0) superlattices the magnetic moments of two nonequivalent atoms in the monolayer are canted to each other near Fe/Cr interface and then swing the direction on perpendicular to the fixed Fe moments. - Highlights: • Frustration destroys the collinear magnetization in Fe/Cr superlattices. • Spin spiral were investigated within basic noncollinear Periodic Anderson Model. • Total energy of the spin spiral is generally more stable than collinear magnetization. • Neither step nor alloying at the Fe/Cr interface is necessary for Spin Spiral stability. • The two interleaved spirals calculated are similar to Fishman’s helical state.

  10. crónicas en adultos

    Directory of Open Access Journals (Sweden)

    Erick Landeros Olvera

    2013-01-01

    Full Text Available Objetivo: a fin de contribuir con la clarificación y el desarrollo de conceptos útiles para la ciencia de enfermería en su práctica, este trabajo utilizó la metodología de Rodgers con el fin de proporcionar una definición del concepto “decisión de cambio” (DC para el mejoramiento de conductas de salud en el contexto de las enfermedades crónicas (obesidad, hipertensión arterial y diabetes. Método: se realizó el análisis de evidencia empírica en bases de datos para identificar atributos, términos subrogados, antecedentes y consecuencias en relación con el concepto DC. De forma complementaria se aplicaron entrevistas semi estructuradas con codificación abierta. Resultados: la decisión de cambio es definida, entonces, como el proceso de elección que requiere de intención y actitud para comprometerse con responsabilidad en el mejoramiento de la conducta de salud, de manera efectiva y permanente respecto de las condiciones sociales y emocionales a las que una persona es sometida ante la presencia de una enfermedad crónica y que requiere de manera impostergable el apoyo familiar y profesional de salud. Conclusión: la decisión de cambio es un juicio de elección que requiere de voluntad permanente para cambiar las conductas de salud y resolver las posibles contingencias que pueda provocar una enfermedad crónica.

  11. Toxic Effects of Cr3+,Cr6+ on the Physiological and Biochemical Characteristics of Tea Plant%Cr3+和Cr6+胁迫对茶树生理生化特性的影响

    Institute of Scientific and Technical Information of China (English)

    唐茜; 冯德建; 杨华; 吴永胜; 谭和平

    2009-01-01

    The toxic effects of different concentrations of Cr3+ and Cr6+ on the physiological and biochemical characteristics of tea plant were studied in Hoagland solution culture.The results indicated that: with the increasing of Cr3+,Cr6+ concentrations,the symptoms of tea plant became obviously; the contents of chlorophyll and the ratio of chlorophyll a and chlorophyll b reduced obviously,and there were obviously negative effects to net photosynthesis rate,intercellular CO2 concentration,transpiration rate and stoma conductivity.Under the Cr3+ stress,the activities of SOD,POD and CAT increased at first and then decreased,under the Cr6+ stress,the activities of SOD and POD increased at first and then decreased too,but the activity of CAT decreased all the time.At the same time,the contents of MDA and proline (Pro),cytomembrane permeability increased obviously with the increasing of Cr3+,Cr6+ concentrations.Therefore,it highlighted that the Cr3+ and Cr6+ stresses could mangle the cytomembrane system,the structures and functions of the major organelles of tea plant,and the toxic effects of Cr6+ on tea plant was stronger than that of Cr3+.%通过水培试验,研究比较了不同浓度(10~60 mg/L)的Cr3+、Cr6+胁迫对茶树叶片一些生理生化指标的影响.结果表明:随Cr3+、Cr6+胁迫浓度的增加,茶树受害程度加深,中毒症状明显;叶绿素含量以及叶绿素a/b比值极显著降低,并对净光合速率、胞间CO2浓度、蒸腾速率及气孔导度产生显著负面影响.Cr3+胁迫下,SOD、POD、CAT活性随Cr3+浓度增加呈先升高后降低趋势;而Cr6+胁迫下,SOD、POD活性也出现先升后降趋势,但CAT活性则持续下降.丙二醛含量、细胞膜透性和脯氨酸含量也随Cr3+、Cr6+浓度增加显著增加,表明Cr3+、Cr6+胁迫对茶树细胞质膜系统及主要细胞器的结构与功能都具有较强的破坏作用,Cr6+的毒害作用强于Cr3+.

  12. Overview of Cr2N And Cr2N/Ag Coatings On Cr-V Ledeburitic Steel: Mechanical Properties and Adhesion

    Directory of Open Access Journals (Sweden)

    Bílek Pavel

    2014-12-01

    Full Text Available Samples made from Vanadis 6 PM ledeburitic tool steel were surface machined, ground and mirror polished. Prior the deposition, they were heat treated to a hardness of 60 HRC. Cr2N- and Cr2N/Ag-coatings were deposited by magnetron sputtering technique, using pure Cr and Ag targets, in a composite low pressure nitrogen/argon atmosphere and at a temperature of 500 °C. The contents of silver in Cr2N/Ag coatings were established 3, 7, 11 and 15 wt. %. Incorporation of silver in the Cr2N-matrix influence the growth rate, namely from the content of 11 wt. %. The nanohardness and Young´s modulus do not change until the content of 11 wt. % where slightly increased but further increasing of silver led to decreasing these values rapidly. The best adhesion was established for coatings with 3 and 7 wt. % of silver.

  13. Facile synthesis of efficient visible active C-doped TiO{sub 2} nanomaterials with high surface area for the simultaneous removal of phenol and Cr(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Mani, A.Daya; Reddy, P.Manoj Kumar; Srinivaas, M. [Department of Chemistry, IIT Hyderabad, Yeddumailaram 502 205 (India); Ghosal, P., E-mail: csubbu@iith.ac.in [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500 058 (India); Xanthopoulos, N. [Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Subrahmanyam, Ch. [Department of Chemistry, IIT Hyderabad, Yeddumailaram 502 205 (India)

    2015-01-15

    Highlights: • Facile synthesis of C-doped TiO{sub 2} nanomaterials with high surface area. • Utilization of citric acid and ascorbic acid as fuels based on evolution of gases. • Enhanced visible activity for the oxidation of phenol and reduction of Cr(VI). • Study of simultaneous oxidation of phenol and reduction of Cr(VI) for the first time. • Proposed plausible mechanism for the simultaneous removal of phenol and Cr(VI). - Abstract: A single step synthesis of carbon doped TiO{sub 2} (anatase) nanomaterials have been reported by using combustion synthesis using ascorbic acid and citric acid fuels. X-ray diffraction studies indicated the formation of nanosized anatase titania, whereas, transmission electron microscopy confirmed the formation of nanosized TiO{sub 2} anatase. The carbon doping into TiO{sub 2} matrix was identified by X-ray photoelectron spectroscopy, whereas, thermogravimetric study quantified the carbon doping. Diffuse reflectance UV–vis spectra indicated the band gap of less than 3 eV, a prerequisite for the photocatalytic activity under visible light irradiation. The N{sub 2} adsorption studies revealed the high surface area (upto 290 m{sup 2}/g) of the synthesized photocatalysts. Typical photocatalytic activity data indicated that the simultaneous removal of Cr(VI) and phenol is advantageous than degradation of the individual pollutants.

  14. The formation model of Ni-Cr oxides on NiCoCrAlY-sprayed coating

    Energy Technology Data Exchange (ETDEWEB)

    Liang, G.Y., E-mail: gyliang@mail.xjtu.edu.cn [Department of Material Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi' an Jiaotong University, Xi' an 710049 (China); Zhu, C.; Wu, X.Y.; Wu, Y. [Department of Material Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi' an Jiaotong University, Xi' an 710049 (China)

    2011-05-15

    The atomic arrangement and distribution of oxides (Cr{sub 2}O{sub 3}, NiCr{sub 2}O{sub 4} and NiO) on the sprayed-NiCoCrAlY coating after oxidation are analyzed. The formation and the growth model of Ni-Cr oxide phases are discussed according to the matching relationship between atoms. The outline character and a scale of spinel NiCr{sub 2}O{sub 4} are discussed. The results show that Cr atoms can form two close-packed arrangements in the crystal plane of Cr{sub 2}O{sub 3} perpendicular to <0 0 1> orientation. The atomic spacing in the first arrangement corresponds to double that of Ni/Ni{sub 3}Al in {l_brace}1 1 1{r_brace} crystal face. This suggests that Ni/Ni{sub 3}Al is the substrate for Cr{sub 2}O{sub 3} to grow along <0 0 1> direction. The lattice mismatch between Cr{sub 2}O{sub 3} and Ni/Ni{sub 3}Al is less than that of Al{sub 2}O{sub 3}, which indicates that Cr{sub 2}O{sub 3} is easier to form than Al{sub 2}O{sub 3} during the oxidation process. The atomic spacing in another close-packed arrangement of Cr{sub 2}O{sub 3} perpendicular to <0 0 1> orientation is approximately equal to that of Ni or Cr in the plane of NiCr{sub 2}O{sub 4} and NiO perpendicular to <1 1 1> orientation. So Cr{sub 2}O{sub 3} can be the substrate for NiCr{sub 2}O{sub 4} and NiO to grow in the <0 0 1> direction. NiCr{sub 2}O{sub 4} and NiO can grow directly along the <1 1 1> orientation on each other. NiCr{sub 2}O{sub 4} can grow outward in the planes of Cr{sub 2}O{sub 3} perpendicular to <0 0 1> and grow inward along <1 1 1> orientation of NiO.

  15. Lymphatic filariasis in Nigeria; micro-stratification overlap mapping (MOM as a prerequisite for cost-effective resource utilization in control and surveillance.

    Directory of Open Access Journals (Sweden)

    Patricia N Okorie

    Full Text Available BACKGROUND: Nigeria has a significant burden of lymphatic filariasis (LF caused by the parasite Wuchereria bancrofti. A major concern to the expansion of the LF elimination programme is the risk of serious adverse events (SAEs associated with the use of ivermectin in areas co-endemic with Loa filariasis. To better understand this, as well as other factors that may impact on LF elimination, we used Micro-stratification Overlap Mapping (MOM to highlight the distribution and potential impact of multiple disease interventions that geographically coincide in LF endemic areas and which will impact on LF and vice versa. METHODOLOGY/PRINCIPAL FINDINGS: LF data from the literature and Federal Ministry of Health (FMoH were collated into a database. LF prevalence distributions; predicted prevalence of loiasis; ongoing onchocerciasis community-directed treatment with ivermectin (CDTi; and long-lasting insecticidal mosquito net (LLIN distributions for malaria were incorporated into overlay maps using geographical information system (GIS software. LF was prevalent across most regions of the country. The mean prevalence determined by circulating filarial antigen (CFA was 14.0% (n = 134 locations, and by microfilaria (Mf was 8.2% (n = 162 locations. Overall, LF endemic areas geographically coincided with CDTi priority areas, however, LLIN coverage was generally low (<50% in areas where LF prevalence was high or co-endemic with L. loa. CONCLUSIONS/SIGNIFICANCE: The extensive database and series of maps produced in this study provide an important overview for the LF Programme and will assist to maximize existing interventions, ensuring cost effective use of resources as the programme scales up. Such information is a prerequisite for the LF programme, and will allow for other factors to be included into planning, as well as monitoring and evaluation activities given the broad spectrum impact of the drugs used.

  16. "Hypothesis for the Modern RNA World": A pervasive Non-coding RNA-Based Genetic Regulation is a Prerequisite for the Emergence of Multicellular Complexity

    Science.gov (United States)

    Lozada-Chávez, Irma; Stadler, Peter F.; Prohaska, Sonja J.

    2011-12-01

    The transitions to multicellularity mark the most pivotal and distinctive events in life's history on Earth. Although several transitions to "simple" multicellularity (SM) have been recorded in both bacterial and eukaryotic clades, transitions to complex multicellularity (CM) have only happened a few times in eukaryotes. A large number of cell types (associated with large body size), increased energy consumption per gene expressed, and an increment of non-protein-coding DNA positively correlate with CM. These three factors can indeed be understood as the causes and consequences of the regulation of gene expression. Here, we discuss how a vast expansion of non-protein-coding RNA (ncRNAs) regulators rather than large numbers of novel protein regulators can easily contribute to the emergence of CM. We also propose that the evolutionary advantage of RNA-based gene regulation derives from the robustness of the RNA structure that makes it easy to combine genetic drift with functional exploration. We describe a model which aims to explain how the evolutionary dynamic of ncRNAs becomes dominated by the accessibility of advantageous mutations to innovate regulation in complex multicellular organisms. The information and models discussed here outline the hypothesis that pervasive ncRNA-based regulatory systems, only capable of being expanded and explored in higher eukaryotes, are prerequisite to complex multicellularity. Thereby, regulatory RNA molecules in Eukarya have allowed intensification of morphological complexity by stabilizing critical phenotypes and controlling developmental precision. Although the origin of RNA on early Earth is still controversial, it is becoming clear that once RNA emerged into a protocellular system, its relevance within the evolution of biological systems has been greater than we previously thought.

  17. H/sub 2/O/sub 2/ production by murine macrophages under activating conditions prerequisite for non-specific tumoricidal activity

    Energy Technology Data Exchange (ETDEWEB)

    Stuart, J.; Leu, R.

    1986-03-05

    The role of an oxidative burst in macrophage-mediated non-specific tumoricidal activity is not well defined. In the present study the effects of macrophage priming by murine ..gamma..-interferon (..gamma..-IFN) and triggering or direct activation by the complement activators, LPS, Lipid A, Poly I:C, and cobra venom factor (CVF) on H/sub 2/O/sub 2/ production were determined using a photometric microassay. Preincubation of oil-elicited peritoneal macrophages (PM theta) from C3HeB/FeJ mice for 24 hr with ..gamma..-IFN resulted in a dose-dependent increase in H/sub 2/O/sub 2/ production during a 2 hr assay which was further amplified by phorbolmyristic acid (PMA). Similar pretreatment of PM theta for 24 hr with LPS, Lipid A, Poly I:C, or CVF resulted in enhanced H/sub 2/O/sub 2/ production at lower concentrations and inhibition at higher concentrations. Priming of PM theta by ..gamma..-IFN and triggering by non-activating concentrations of LPS or CVF for 24 hr produced synergistic augmentation of H/sub 2/O/sub 2/ production which was amplified by PMA. A correlation was established between H/sub 2/O/sub 2/ production by PM theta in response to the various activators and macrophage-mediated non-specific cytotoxicity for sheep erythrocyte targets. These observation suggest probability that H/sub 2/O/sub 2/ and possibly other cytotoxic end-products of an oxidative burst are produced by activated macrophages under precise conditions established to be prerequisite for non-specific tumoricidal activity.

  18. β2 integrin-mediated crawling on endothelial ICAM-1 and ICAM-2 is a prerequisite for transcellular neutrophil diapedesis across the inflamed blood-brain barrier.

    Science.gov (United States)

    Gorina, Roser; Lyck, Ruth; Vestweber, Dietmar; Engelhardt, Britta

    2014-01-01

    In acute neuroinflammatory states such as meningitis, neutrophils cross the blood-brain barrier (BBB) and contribute to pathological alterations of cerebral function. The mechanisms that govern neutrophil migration across the BBB are ill defined. Using live-cell imaging, we show that LPS-stimulated BBB endothelium supports neutrophil arrest, crawling, and diapedesis under physiological flow in vitro. Investigating the interactions of neutrophils from wild-type, CD11a(-/-), CD11b(-/-), and CD18(null) mice with wild-type, junctional adhesion molecule-A(-/-), ICAM-1(null), ICAM-2(-/-), or ICAM-1(null)/ICAM-2(-/-) primary mouse brain microvascular endothelial cells, we demonstrate that neutrophil arrest, polarization, and crawling required G-protein-coupled receptor-dependent activation of β2 integrins and binding to endothelial ICAM-1. LFA-1 was the prevailing ligand for endothelial ICAM-1 in mediating neutrophil shear resistant arrest, whereas Mac-1 was dominant over LFA-1 in mediating neutrophil polarization on the BBB in vitro. Neutrophil crawling was mediated by endothelial ICAM-1 and ICAM-2 and neutrophil LFA-1 and Mac-1. In the absence of crawling, few neutrophils maintained adhesive interactions with the BBB endothelium by remaining either stationary on endothelial junctions or displaying transient adhesive interactions characterized by a fast displacement on the endothelium along the direction of flow. Diapedesis of stationary neutrophils was unchanged by the lack of endothelial ICAM-1 and ICAM-2 and occurred exclusively via the paracellular pathway. Crawling neutrophils, although preferentially crossing the BBB through the endothelial junctions, could additionally breach the BBB via the transcellular route. Thus, β2 integrin-mediated neutrophil crawling on endothelial ICAM-1 and ICAM-2 is a prerequisite for transcellular neutrophil diapedesis across the inflamed BBB.

  19. Common definition for categories of clinical research: a prerequisite for a survey on regulatory requirements by the European Clinical Research Infrastructures Network (ECRIN)

    LENUS (Irish Health Repository)

    Kubiak, Christine

    2009-10-16

    Abstract Background Thorough knowledge of the regulatory requirements is a challenging prerequisite for conducting multinational clinical studies in Europe given their complexity and heterogeneity in regulation and perception across the EU member states. Methods In order to summarise the current situation in relation to the wide spectrum of clinical research, the European Clinical Research Infrastructures Network (ECRIN) developed a multinational survey in ten European countries. However a lack of common classification framework for major categories of clinical research was identified, and therefore reaching an agreement on a common classification was the initial step in the development of the survey. Results The ECRIN transnational working group on regulation, composed of experts in the field of clinical research from ten European countries, defined seven major categories of clinical research that seem relevant from both the regulatory and the scientific points of view, and correspond to congruent definitions in all countries: clinical trials on medicinal products; clinical trials on medical devices; other therapeutic trials (including surgery trials, transplantation trials, transfusion trials, trials with cell therapy, etc.); diagnostic studies; clinical research on nutrition; other interventional clinical research (including trials in complementary and alternative medicine, trials with collection of blood or tissue samples, physiology studies, etc.); and epidemiology studies. Our classification was essential to develop a survey focused on protocol submission to ethics committees and competent authorities, procedures for amendments, requirements for sponsor and insurance, and adverse event reporting following five main phases: drafting, consensus, data collection, validation, and finalising. Conclusion The list of clinical research categories as used for the survey could serve as a contribution to the, much needed, task of harmonisation and simplification of the

  20. Common definition for categories of clinical research: a prerequisite for a survey on regulatory requirements by the European Clinical Research Infrastructures Network (ECRIN

    Directory of Open Access Journals (Sweden)

    Sanz Nuria

    2009-10-01

    Full Text Available Abstract Background Thorough knowledge of the regulatory requirements is a challenging prerequisite for conducting multinational clinical studies in Europe given their complexity and heterogeneity in regulation and perception across the EU member states. Methods In order to summarise the current situation in relation to the wide spectrum of clinical research, the European Clinical Research Infrastructures Network (ECRIN developed a multinational survey in ten European countries. However a lack of common classification framework for major categories of clinical research was identified, and therefore reaching an agreement on a common classification was the initial step in the development of the survey. Results The ECRIN transnational working group on regulation, composed of experts in the field of clinical research from ten European countries, defined seven major categories of clinical research that seem relevant from both the regulatory and the scientific points of view, and correspond to congruent definitions in all countries: clinical trials on medicinal products; clinical trials on medical devices; other therapeutic trials (including surgery trials, transplantation trials, transfusion trials, trials with cell therapy, etc.; diagnostic studies; clinical research on nutrition; other interventional clinical research (including trials in complementary and alternative medicine, trials with collection of blood or tissue samples, physiology studies, etc.; and epidemiology studies. Our classification was essential to develop a survey focused on protocol submission to ethics committees and competent authorities, procedures for amendments, requirements for sponsor and insurance, and adverse event reporting following five main phases: drafting, consensus, data collection, validation, and finalising. Conclusion The list of clinical research categories as used for the survey could serve as a contribution to the, much needed, task of harmonisation and

  1. Comparison of CrAlN layers obtained with one (CrAl) or two targets (Cr and Al) by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Nouveau, C., E-mail: nouveau@cluny.ensam.fr [Laboratoire Bourguignon des Materiaux et Procedes, LaBoMaP, Centre Arts et Metiers ParisTech, Rue Porte de Paris, F-71250, Cluny (France); Tlili, B., E-mail: tlilii_brahim@yahoo.fr [UR. Mecanique Appliquee, Ingenierie et Industrialisation (M.A2I), ENIT, BP 37, Le Belvedere, 1002, Tunis (Tunisia); Aknouche, H., E-mail: h.aknouche@yahoo.fr [URMPE, F.S.I. Universite M' Hamed Bougara, 35000, Boumerdes Algeria (Algeria); Benlatreche, Y., E-mail: benlatrechey@yahoo.fr [Laboratoire de Mecanique de Lille, LML CNRS UMR 8107, Centre Arts et Metiers ParisTech, 8 Boulevard Louis XIV, F-59046, Lille cedex (France); Patel, B., E-mail: Bhavesh.PATEL-7@etudiants.ensam.eu [Laboratoire Bourguignon des Materiaux et Procedes, LaBoMaP, Centre Arts et Metiers ParisTech, Rue Porte de Paris, F-71250, Cluny (France)

    2012-01-31

    The aim of this study is to compare the properties of CrAlN coatings obtained by magnetron sputtering with one (CrAl) or two targets (Cr and Al). The influence of parameters such as the target bias voltage, the working pressure, the deposition time and the bias voltage applied on the Cr or Al targets on the properties of the layers was studied. We characterized the films by X-ray Diffraction, Scanning Electron Microscopy, coupled with Energy Dispersive Spectroscopy, nanoindentation and their residual stresses were also determined. The optimal films obtained with both methods are well crystallized, well-adherent to the substrate, and contained similar amounts of Al (20-30 at.%). The optimal coatings synthesized with one target presented properties not as good as those realized with two targets. Nevertheless, films made with one target showed a lower frictional coefficient probably due to composition control. The lack of compositional control with the use of one target limits the optimization process. With two targets, we have greater control over the film composition. This leads to higher hardness, lower stresses, and improved Young's modulus over films produced with a single CrAl target. Additionally, the morphologies are different (columnar with CrAl and dense with Cr and Al). To conclude, it seems more justified to work if possible with two independent targets. - Highlights: Black-Right-Pointing-Pointer CrAlN layers obtained with a (Cr75Al25) target or Cr and Al independent targets. Black-Right-Pointing-Pointer Lower friction coefficient and better crystallinity obtained with a sintered target. Black-Right-Pointing-Pointer Al content of layers obtained with a sintered target limited and fixed. Black-Right-Pointing-Pointer Better tribological properties of layers obtained with two targets. Black-Right-Pointing-Pointer No economical, practical and scientific interest to work with a sintered target.

  2. THE EFFECT OF RARE EARTH ELEMENTS ON Cr PRECIPITATIONS IN A Cu-0.8WT%Cr ALLOY

    Directory of Open Access Journals (Sweden)

    Gewang Shuai

    2011-05-01

    Full Text Available The microstructural evolution of Cu-based alloys during aging was studied using a quantitative metallographic method. Samples were cut from ingots of Cu-0.8wt%Cr and Cu-0.8wt%Cr-RE alloys. These were solution treated at 1000 ºC for 1.5h and subsequently quenched in water, then separately aged at 480 ºC for different durations. The microstructures were observed by optical microscope, and the characteristic geometric parameters of precipitated Cr phase, including volume fraction VV, face density NA, mean diameter and roundness, were measured. These data provided more details about the process of aging. The results showed that precipitation of Cr phase occurred in the form of particles during aging. Rare earth elements promoted the precipitation of Cr phase and dispersed Cr particles. The phenomenon of overaging came earlier in Cu-Cr-RE than in Cu-Cr. In the present work, the optimal aging time at 480 ºC was 2 hrs for the Cu-0.8wt%Cr-RE alloy and 3 hours for the Cu-0.8wt%Cr alloy.

  3. Investigation on Mechanical Properties of 9%Cr/CrMoV Dissimilar Steels Welded Joint

    Science.gov (United States)

    Liu, Xia; Lu, Fenggui; Yang, Renjie; Wang, Peng; Xu, Xiaojin; Huo, Xin

    2015-04-01

    Advanced 9%Cr steel with good heat resistance and CrMoV with good toughness were chosen as candidate materials to fabricate combined rotor for steam turbine operating at over 620 °C. But the great difference in base metals properties presents a challenge in achieving sound defect-free joint with optimal properties in dissimilar welded rotor. In this paper, appropriate selection of filler metal, welding parameters, and post-weld heat treatment was combined to successfully weld 1100-mm-diameter 9%Cr/CrMoV dissimilar experimental rotor through ultra-narrow gap submerge arc welding. Some properties such as hardness, low-cycle fatigue (LCF), and high-cycle fatigue (HCF) combined with microstructural characterization qualify the integrity of the weld. Microstructural analysis indicated the presence of high-temperature tempered martensite as the phase responsible for the improved properties obtained in the weld. The Coffin-Manson parameters were obtained by fitting the data in LCF test, while the conditional fatigue strength was derived from the HCF test based on S-N curve. Analysis of hardness profile showed that the lowest value occurred at heat-affected zone adjacent to base metal which represents the appropriate location of fracture for the samples after LCF and HCF tests.

  4. Regularization of Local CR-Automorphisms of Real-Analytic CR-Manifolds

    CERN Document Server

    Isaev., A

    2009-01-01

    Let M be a connected generic real-analytic CR-submanifold of a finite-dimensional complex vector space E. Suppose that for every point a in M the Lie algebra hol(M,a) of germs of all infinitesimal real-analytic CR-automorphisms of M at a is finite-dimensional and its complexification contains all constant vector fields and the Euler vector field. Under these assumptions we show that: (I) every hol(M,a) consists of polynomial vector fields, hence coincides with the Lie algebra hol(M) of all infinitesimal real-analytic CR-automorphisms of M; (II) every local real-analytic CR-automorphism of M extends to a birational transformation of E, and (III) the group Bir(M) generated by such birational transformations is realized as a group of projective transformations upon embedding E as a Zariski open subset into a projective algebraic variety. Under additional assumptions the group Bir(M) is shown to have the structure of a Lie group with at most countably many connected components and Lie algebra hol(M). All of the a...

  5. Sintering behaviour and mechanical properties of Cr3C2–NiCr cermets

    Indian Academy of Sciences (India)

    A Özer; Y K Tür

    2013-10-01

    Cr3C2–NiCr cermets are used as metal cutting tools due to their relatively high hardness and low sintering temperatures. In this study, a powder mixture consisting of 75 wt% Cr3C2–25 wt% NiCr was sintered at four different temperatures and characterized for itsmicrostructure and mechanical properties. The highest relative density obtained was 97% when sintered at 1350 °C. As the relative density increased, elastic modulus, transverse rupture strength, fracture toughness and hardness of the samples reached to a maximum of 314 GPa, 810 MPa, 10.4 MPa.m1/2 and 11.3 GPa, respectively. However, sintering at 1400 °C caused further grain growth and pore coalescence which resulted in decreasing density and degradation of all mechanical properties. Fracture surface investigation showed that the main failure mechanism was the intergranular fracture of ceramic phase accompanied by the ductile fracture of the metal phase which deformed plastically during crack propagation and enhanced the fracture toughness.

  6. Global Cr-isotope distributions in surface seawater and incorporation of Cr isotopes into carbonate shells

    DEFF Research Database (Denmark)

    Paulukat, Cora Stefanie; Frei, Robert; Vögelin, Andrea Regula

    In this study we present the Cr-isotope composition of surface seawater from several locations worldwide. In addition to the samples from the oceans (Atlantic Ocean, Pacific Ocean, Southern Ocean and Artic Ocean) we analysed water samples from areas with a more limited water exchange (Mediterrane...

  7. Cr{sub 2}Nb-based alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A. [Oak Ridge National Lab., TN (United States)] [and others

    1996-08-01

    Alloys of Cr-Cr{sub 2}Nb with exceptionally high strength at 1200{degrees}C have been developed. However, these compositions suffer from limited ductility and toughness at room temperature. Despite improvements from processing modifications, as-fabricated defects still limit room temperature mechanical behavior. In contrast, an alloy system with only a small mismatch of the coefficients of thermal expansion of the two phases, Cr-Cr{sub 2}Zr, showed good fabricability. However, these alloys are weaker than Cr-Cr{sub 2}Nb compositions at high temperatures and have poor oxidation resistance. Silicide coatings can provide high-temperature oxidation and sulfidation protection of these alloys. Improvements in room temperature mechanical properties of Laves-phase-strengthened alloys will rely on further development based on increasing the ductility of the matrix phase by impurity control and compositional modifications.

  8. Density of Ni-Cr Alloy in the Mushy State

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of Ni-Cr alloy in the mushy state has been measured using the modified sessile drop method. The density of Ni-Cr alloy in the mushy state was found to decrease with increasing temperature and Cr concentration in alloy.The molar volume of Ni-Cr alloy in the mushy state therefore increases with increasing the Cr concentration in alloy.The ratio of the difference of density divided by the temperature difference between liquidus and solidus temperatures decreases with increasing Cr concentration. The density of the alloy increased with the precipitation of a solid phase in alloy during the solidification process. The temperature dependence of the density of alloy in the mushy state was not linear but biquadratic.

  9. Atomic displacements in dilute alloys of Cr, Nb and Mo

    CERN Document Server

    Sharma, H

    2002-01-01

    Kanzaki lattice static method is used to calculate the atomic displacements due to substitutional impurities in 3d (Cr) and 4d (Nb, Mo) metals. Wills and Harrison interatomic potential is used to calculate dynamical matrix and the impurity-induced forces up to second nearest neighbors. The calculated atomic displacements for 3d, 4d and 5d impurities in Cr (V, Mn, Fe, Ni, Nb, Mo, Ta and W), Nb (V, Cr, Mn, Fe, Zr, Mo, Ta and W) and Mo (V, Cr, Mn, Fe, Zr, Nb, Ta and W) are tabulated up to 10 NN's. The strain field due to 3d impurities is least in Cr metal while it is larger in Nb and Mo metals. For 4d and 5d impurities the strain is larger in Cr metal than in Nb and Mo hosts. Similar trend is found for relaxation energies also. (author)

  10. Complex magnetic behavior in GdCrO3

    Science.gov (United States)

    Mahana, Sudipta; Manju, U.; Topwal, D.

    2017-05-01

    Magnetic interactions in Gadolinium orthochromites (GdCrO3) are quite complex. It shows strong temperature dependency related to Gd3+-Gd3+, Gd3+-Cr3+ and Cr3+-Cr3+ interactions, resulting in exotic phenomena like spin flipping and spin reorientation. These behaviors are successfully explained by considering Cr 3d-Gd 4f magnetic coupling. The nearest neighbor symmetric and antisymmetric exchange coupling in Cr-sublattice was found to be Je = 11.058 K and D = 2.64 K from modified Curie-Weiss law modeled by Moriya, while positive Zeeman energy between net moments and the applied external magnetic fields was found to drive spin flipping.

  11. Atomic scale structure investigations of epitaxial Fe/Cr multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Kąc, M., E-mail: malgorzata.kac@ifj.edu.pl [The Henryk Niewodniczański Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków (Poland); Morgiel, J. [Institute of Metallurgy and Materials Science PAN, 25 Reymonta St., 30-059 Kraków (Poland); Polit, A.; Zabila, Y.; Marszałek, M. [The Henryk Niewodniczański Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków (Poland)

    2014-06-01

    Fe/Cr multilayers were deposited by molecular beam epitaxy on the MgO(1 0 0) substrate. Structural properties of the samples were analyzed by low energy electron diffraction, high resolution transmission electron microscopy (HRTEM), as well as by X-ray reflectivity, conversion electron Mössbauer spectroscopy (CEMS) and Auger electron spectroscopy. Investigations revealed multilayered system built of well-ordered Fe and Cr thin films with (1 0 0) orientation. A high geometrical perfection of the system, i.e. planar form of interfaces and reproducible thickness of layers, was also proven. Fe/Cr interface roughness was determined to be 2–3 atomic layers. CEMS studies allowed to analyze at atomic scale the structure of buried Fe/Cr interfaces, as well as to distinguish origin of interface roughness. Roughnesses resulting from interface corrugations and from the Fe–Cr interdiffusion at interfaces were observed. Fe/Cr multilayers showed strong antiferromagnetic coupling of Fe layers.

  12. Atomic displacements in dilute alloys of Cr, Nb and Mo

    Indian Academy of Sciences (India)

    Hitesh Sharma; S Prakash

    2002-09-01

    Kanzaki lattice static method is used to calculate the atomic displacements due to substitutional impurities in 3d (Cr) and 4d (Nb, Mo) metals. Wills and Harrison interatomic potential is used to calculate dynamical matrix and the impurity-induced forces up to second nearest neighbors. The calculated atomic displacements for 3d, 4d and 5d impurities in Cr (V, Mn, Fe, Ni, Nb, Mo, Ta and W), Nb (V, Cr, Mn, Fe, Zr, Mo, Ta and W) and Mo (V, Cr, Mn, Fe, Zr, Nb, Ta and W) are tabulated up to 10 NN’s. The strain field due to 3d impurities is least in Cr metal while it is larger in Nb and Mo metals. For 4d and 5d impurities the strain is larger in Cr metal than in Nb and Mo hosts. Similar trend is found for relaxation energies also.

  13. Enfermedad pulmonar obstructiva crónica

    Directory of Open Access Journals (Sweden)

    Reinaldo Pino Blanco

    2011-01-01

    Full Text Available La enfermedad pulmonar obstructiva crónica se ha convertido en una de las enfermedades crónicas atendidas con mayor frecuencia en la atención primaria de salud. Produce altas tasas de morbilidad y mortalidad en todo el mundo, con una evolución lenta aunque progresivamente mortal, a pesar de tratarse de una enfermedad prevenible, que depende en gran medida, del hábito de fumar. La prevalencia variará según el consumo de tabaco, y se espera que siga aumentando en los próximos 25 años. La mortalidad y morbilidad son cada vez mayores, lo que supone un enorme gasto sanitario, social y personal, pero es una enfermedad potencialmente modificable, motivo por el que requiere de un abordaje multifactorial.Chronic Obstructive Pulmonary Disease has become one of the most frequently treated chronic diseases in primary health care. High rates of morbidity and mortality are worldwide related to this disease. Although it is a preventable disease closely related to smoking, its evolution is slow but progressively fatal. Prevalence varies according to tobacco consumption and is expected to increase in the next 25 years. Even when it is a potentially modifiable disease, mortality and morbidity are also increasing, causing a major health, social and personal spending. For all these reasons, a multifactorial approach is needed both, for health and social issues.

  14. Crimen y crítica

    Directory of Open Access Journals (Sweden)

    Américo Cristófalo

    2000-11-01

    Full Text Available A partir de "El asesinato considerado como una de las bellas artes", de Thomas De Ouincey, y de "Pluma, lápiz y veneno", de Oscar Wilde, se indagan los efectos que el concepto de "lo sublime" (tomado en las consideraciones de Burke y Kant produjo en el debate acerca de la autonomización de la critica durante el Siglo XIX. Los textos de De Quincey Wilde recogen la dimensión de "lo sublime" en relación con el asesinato y formulan a partir de el una hipótesis acerca del método y los alcances de la critica de ante. Este artículo muestra en qué medida el carácter irrepresentable de lo que Burke y Kant llaman lo sublime regresa sobre la conciencia crítica bajo la forma de una nueva apertura del horizonte moral del juicio y busca poner en cuestión la idea de que pueda pensarse una equivalencia entre "soberanía" "autonomía profesional" de la crítica.

  15. Enfermedad pulmonar obstructiva crónica

    Directory of Open Access Journals (Sweden)

    Reinaldo Pino Blanco

    2011-01-01

    Full Text Available La enfermedad pulmonar obstructiva crónica se ha convertido en una de las enfermedades crónicas atendidas con mayor frecuencia en la atención primaria de salud. Produce altas tasas de morbilidad y mortalidad en todo el mundo, con una evolución lenta aunque progresivamente mortal, a pesar de tratarse de una enfermedad prevenible, que depende en gran medida, del hábito de fumar. La prevalencia variará según el consumo de tabaco, y se espera que siga aumentando en los próximos 25 años. La mortalidad y morbilidad son cada vez mayores, lo que supone un enorme gasto sanitario, social y personal, pero es una enfermedad potencialmente modificable, motivo por el que requiere de un abordaje multifactorial.Chronic Obstructive Pulmonary Disease has become one of the most frequently treated chronic diseases in primary health care. High rates of morbidity and mortality are worldwide related to this disease. Although it is a preventable disease closely related to smoking, its evolution is slow but progressively fatal. Prevalence varies according to tobacco consumption and is expected to increase in the next 25 years. Even when it is a potentially modifiable disease, mortality and morbidity are also increasing, causing a major health, social and personal spending. For all these reasons, a multifactorial approach is needed both, for health and social issues.

  16. Crimen y crítica

    Directory of Open Access Journals (Sweden)

    Américo Cristófalo

    2001-11-01

    Full Text Available A partir de "El asesinato considerado como una de las bellas artes", de Thomas De Ouincey, y de "Pluma, lápiz y veneno", de Oscar Wilde, se indagan los efectos que el concepto de "lo sublime" (tomado en las consideraciones de Burke y Kant produjo en el debate acerca de la autonomización de la critica durante el Siglo XIX. Los textos de De Quincey Wilde recogen la dimensión de "lo sublime" en relación con el asesinato y formulan a partir de el una hipótesis acerca del método y los alcances de la critica de ante. Este artículo muestra en qué medida el carácter irrepresentable de lo que Burke y Kant llaman lo sublime regresa sobre la conciencia crítica bajo la forma de una nueva apertura del horizonte moral del juicio y busca poner en cuestión la idea de que pueda pensarse una equivalencia entre "soberanía" "autonomía profesional" de la crítica.

  17. Three dimensional modeling of CR propagation

    CERN Document Server

    Gaggero, Daniele; Di Bernardo, Giuseppe; Evoli, Carmelo; Grasso, Dario

    2013-01-01

    We present here a major upgrade of DRAGON, a numerical package that computes the propagation of a wide set of CR species from both astrophysical and exotic origin in the Galaxy in a wide energy range from tens of MeV to tens of TeV. DRAGON takes into account all relevant processes in particular diffusion, convection, reacceleration, fragmentation and energy losses. For the first time, we present a full 3D version of DRAGON with anisotropic position-dependent diffusion. In this version, the propagation is calculated within a 3D cartesian grid and the user is able to implement realistic and structured three dimensional source, gas and regular magnetic field distributions. Moreover, it is possible to specify an arbitrary function of position and rigidity for the diffusion coefficients in the parallel and perpendicular direction to the regular magnetic field of the Galaxy. The code opens many new possibilities in the study of CR physics. In particular, we can study for the first time the impact of the spiral arm ...

  18. Crítica de Libros.

    Directory of Open Access Journals (Sweden)

    Emilia García Castro

    1991-01-01

    Full Text Available Desarrollos contemporáneos recientes en psicoanálisis. Una evaluación crítica. Morris N. Eagle. Paidós 1988. Emilia García Castro Crónica de una investigación. La Evolución de la Terapia Familiar en la Obra de Mara· Selvini-Palazzoli. Compilador Matteo Selvini. Ed. Paidós, 1990. 363 páginas. 2000 pts. Beatriz Rodriguez Vega Mental health care delivery: Innovations, impediments and implementation. 1. Marks y R. Scott, Editores. Cambridge University Press. 1990. A. García-Ordás Introducción a la psicopatología y la psiquiatría. Preguntas-respuestas. Sistema de autoevaluación. J. Vallejo Ruiloba. Casos Clínicos, Psiquiatría. Salvat Editores, 1991. A. García-Ordás Imarginaciones: (Márgenes e imágenes de la vida cotidiana s. Lamas Crego La Región Ediciones (Orense 1.990. Tiburcio Angosto Saura Conxo, siempre el primer día (aproximación al diario del Profesor Villamil. J. L. Mediavilla. Fundación Dolores Medio (Oviedo. Tiburcio Angosto Saura

  19. Indigenous amino acids in primitive CR meteorites

    CERN Document Server

    Martins, Z; Orzechowska, G E; Fogel, M L; Ehrenfreund, P

    2008-01-01

    CR meteorites are among the most primitive meteorites. In this paper, we report the first measurements of amino acids in Antarctic CR meteorites, two of which show the highest amino acid concentrations ever found in a chondrite. EET92042, GRA95229 and GRO95577 were analyzed for their amino acid content using high performance liquid chromatography with UV fluorescence detection (HPLC-FD) and gas chromatographymass spectrometry (GC-MS). Our data show that EET92042 and GRA95229 are the most amino acid-rich chondrites ever analyzed, with total amino acid concentrations ranging from 180 parts-per-million (ppm) to 249 ppm. GRO95577, however, is depleted in amino acids. The most abundant amino acids present in the EET92042 and GRA95229 meteorites are the alpha-amino acids glycine, isovaline, alpha-aminoisobutyric acid (alpha-AIB), and alanine, with delta13C values ranging from +31.6per mil to +50.5per mil. The carbon isotope results together with racemic enantiomeric ratios determined for most amino acids strongly i...

  20. X-ray diffraction investigation of phase stability in the Co-Cr-O and the Fe-Co-Cr-O systems in air at 1323 K

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Mogensen, M.B.; Linderoth, S.

    2005-01-01

    with the rock salt structure was identified in the cobalt-rich mixtures, suggesting that these compositions belong to a two-phase field in the Cr-Co-O phase diagram. In the Cr-rich mixtures, both non-reacted Cr2O3 and CoCr2O4 were identified. The decomposition temperatures of Co3O4, Co2CrO4, and Co1.5Cr1.5O4...

  1. Residual ferrite formation in 12CrODS steels

    OpenAIRE

    Ukai, S.; Kudo, Y.; Wu, X; N. Oono; Hayashi, S.(University of Tokyo, Tokyo, Japan); Ohtsuka, S; T. Kaito

    2014-01-01

    Increasing Cr content from 9 to 12 mass% leads to superior corrosion and high-temperature oxidation resistances, and usually changes microstructure from martensite to a ferrite. To make transformable martensitic type of 12CrODS steels that have superior processing capability by using alpha/gamma phase transformation, alloy design was conducted through varying nickel content. The structure of 12CrODS steels was successfully modified from full ferrite to a transformable martensite-base matrix c...

  2. Cr:ZnSe guided wave lasers and materials

    Science.gov (United States)

    McDaniel, Sean; Lancaster, Adam; Stites, Ronald; Thorburn, Fiona; Kar, Ajoy; Cook, Gary

    2017-02-01

    We describe a variety of technological advances in the development of efficient, powerful, and continuously tunable Cr:ZnSe lasers operating in the 2.3-2.7 μm spectral region. This includes the development of compact "single chip" waveguide Cr:ZnSe lasers, waveguide mode-locked Cr:ZnSe lasers, and the creation of homogeneously broadened laser material.

  3. Mechanical properties of irradiated 9Cr-2WVTa steel

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Alexander, D.J. [Oak Ridge National Lab., TN (United States); Rieth, M. [Forschungszentrum Karlsruhe (Germany). Inst. fuer Materialforschung II

    1998-09-01

    An Fe-9Cr-2W-0.25V-0.07Ta-0.1C (9Cr-2WVTa) steel has excellent strength and impact toughness before and after irradiation in the Fast Flux Test Facility and the High Flux Reactor (HFR). The ductile-brittle transition temperature (DBTT) increased only 32 C after 28 dpa at 365 C in FFTF, compared to a shift of {approx}60 C for a 9Cr-2WV steel--the same as the 9Cr-2WVTa steel but without tantalum. This difference occurred despite the two steels having similar tensile but without tantalum. This difference occurred despite the two steels having similar tensile properties before and after irradiation. The 9Cr-2WVTa steel has a smaller prior-austenite grain size, but otherwise microstructures are similar before irradiation and show similar changes during irradiation. The irradiation behavior of the 9Cr-2WVTa steel differs from the 9Cr-2WV steel and other similar steels in two ways: (1) the shift in DBTT of the 9Cr-2WVTa steel irradiated in FFTF does not saturate with fluence by {approx}28 dpa, whereas for the 9Cr-2WV steel and most similar steels, saturation occurs at <10 dpa, and (2) the shift in DBTT for 9Cr-2WVTa steel irradiated in FFTF and HFR increased with irradiation temperature, whereas it decreased for the 9Cr-2WV steel, as it does for most similar steels. The improved properties of the 9Cr-2WVTa steel and the differences with other steels were attributed to tantalum in solution.

  4. Electrical resistivity of V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Gubbi, A.N.; Eatherly, W.S. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    Room temperature electrical resistivity measurements have been performed on vanadium alloys containing 3-6%Cr and 3-6%Ti in order to evaluate the microstructural stability of these alloys. A nonlinear dependence on Cr and Ti concentration was observed, which suggests that either short range ordering or solute precipitation (perhaps in concert with interstitial solute clustering) has occurred in V-6Cr-6Ti.

  5. Retrotransposable CR1-like elements in crotalinae snake genomes.

    Science.gov (United States)

    Nobuhisa, I; Ogawa, T; Deshimaru, M; Chijiwa, T; Nakashima, K I; Chuman, Y; Shimohigashi, Y; Fukumaki, Y; Hattori, S; Ohno, M

    1998-06-01

    A part of the 3'-flanking region of BP-II gene, which is one of Trimeresurus flavoviridis venom gland phospholopase A2 (PLA2) isozyme genes, has a region homologous to avian chicken repeat 1 (CR1)-element. In the present study, ten CR1-like elements were further identified in T. gramineus venom gland PLA2 isozyme genes, T. flavoviridis PLA2 inhibitor (PLI) genes, and T. flavoviridis and T. gramineus TATA-box binding protein (TBP) genes. Southern blot analysis using a probe for CR1 showed that Crotalinae snake genomes contain a number of CR1-like elements.

  6. FMR measurements on CoCr/NiFe double layers

    OpenAIRE

    Stam, M.T.H.C.W.; Gerritsma, G.J.; Lodder, J. C.; Popma, Th.J.A.

    1988-01-01

    CoCr/NiFe double layers were measured by ferromagnetic resonance (FMR) for different angles of the applied field. Several resonance curves were observed for CoCr, which are attributed to the different layers of a magnetically stratified CoCr. This was investigated by carrying out FMR measurements on a single CoCr sample and removing successive layers by ion beam milling. The origin of some of the curves is still unclear. One resonance curve is attributed to the top or bulk layer and another t...

  7. Microstructure of directionally solidified Cu-Cr composites

    Institute of Scientific and Technical Information of China (English)

    毕晓勤; 李金山; 胡锐; 耿兴国; 朱琦; 傅恒志

    2004-01-01

    Cu-Cr composites were prepared by self-made directional solidification equipment with the high temperature gradient and double-zone heating. The microstructural evolution was investigated during the directional solidification with the different solidification rate for Cu-1.0%Cr, Cu-1.7%Cr and Cu-5.6%Cr alloys, respectively. It is shown that for the hypoeutectic Cu-1.0%Cr alloy, the general microstructures consist of primary α(Cu) phase and the rod-like or needle-like (α+β) eutectics, and for the hypereutectic Cu-1. 7%Cr and Cu-5.6%Cr alloys, α(Cu)phase, primary β(Cr) phase and (α+β) eutectics coexist. With the increase of the solidification rate, the morphology evolution of every phase is that, 1st cellular(dendrite) of α(Cu) phase thins and cellular(dendrite) spacing shortens gradually, (α+β) eutectics set in α(Cu) cellular or dendrite, and primary β(Cr) phase distributes unevenly on α (Cu) matrix, whose morphology undergoes the change from dendrite to particle.

  8. Cr(III REMOVAL FROM AQUEOUS SOLUTIONS BY ADSORPTION

    Directory of Open Access Journals (Sweden)

    Mehmet MAHRAMANLIOĞLU

    2002-03-01

    Full Text Available The adsorption of Cr (III on the adsorbent produced from lignite coal was studied as a function of time, amount of adsorbent, pH and temperature. Cr (III adsorption data obeyed Freundlich, Langmuir and Lagergren equations. The values of ?H0, ?S0 and ?G0 were calculated. The results showed that adsorption is endothermic. The negative free energy values indicate that the process of Cr (III adsorption is spontaneous and favoured at high temperatures. The adsorption of Cr (III in the presence of different cations was also studied at 200 C. The results were correlated with the ionic potential of cations.

  9. CR mammography: Design and implementation of a quality control program

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Ramirez, A.; Brandan, M. E.; Villasenor-Navarro, Y.; Galvan, H. A.; Ruiz-Trejo, C. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, DF 04510 (Mexico); Departamento de Radiodiagnostico, Instituto Nacional de Cancerologia, DF 14080 (Mexico); Instituto de Fisica, Universidad Nacional Autonoma de Mexico, DF 04510 (Mexico)

    2012-10-23

    Despite the recent acquisition of significant quantities of computed radiography CR equipment for mammography, Mexican regulations do not specify the performance requirements for digital systems such as those of CR type. The design of a quality control program QCP specific for CR mammography systems was thus considered relevant. International protocols were taken as reference to define tests, procedures and acceptance criteria. The designed QCP was applied in three CR mammography facilities. Important deficiencies in spatial resolution, noise, image receptor homogeneity, artifacts and breast thickness compensation were detected.

  10. Effect of acidizing solutions on K{sub IEAC} of 13 Cr and 22 Cr stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    McCoy, T.H.; Mackey, S.T.; Walker, M.L. [Halliburton Energy Services, Duncan, OK (United States)

    1994-12-31

    Fracture mechanics environment-assisted cracking tests, using precracked TM0177-90 double cantilever beam (DCB) specimens, were performed on 13 Cr (UNS S42000) martensitic stainless steel and 22 Cr (UNS S31803) duplex stainless steel in stimulation acidizing solutions to simulate downhole conditions. The acidizing solutions used were 15% HCl and 12% HCl-3% HF with proprietary inhibitors. The 13 Cr material was quenched and double tempered to meet the mechanical property requirements of API Spec 5CT Grade L-80. The 22 Cr material was grade 130 (130 ksi minimum yield strength) cold reduced tubing. This paper shows that the low strength 13 Cr material is not very susceptible to crack propagation in acidizing solutions. The high strength 22 Cr material, however, did show susceptibility to crack propagation in the same acidizing solutions while no cracking occurred in NACE TM0177-90 sour brine solution.

  11. Spin-driven ordering of Cr in the equiatomic high entropy alloy NiFeCrCo

    Energy Technology Data Exchange (ETDEWEB)

    Niu, C.; Zaddach, A. J.; Oni, A. A.; Sang, X.; LeBeau, J. M.; Koch, C. C.; Irving, D. L., E-mail: dlirving@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Hurt, J. W. [Department of Physics, Furman University, Greenville, South Carolina 29613 (United States)

    2015-04-20

    Spin-driven ordering of Cr in an equiatomic fcc NiFeCrCo high entropy alloy (HEA) was predicted by first-principles calculations. Ordering of Cr is driven by the reduction in energy realized by surrounding anti-ferromagnetic Cr with ferromagnetic Ni, Fe, and Co in an alloyed L1{sub 2} structure. The fully Cr-ordered alloyed L1{sub 2} phase was predicted to have a magnetic moment that is 36% of that for the magnetically frustrated random solid solution. Three samples were synthesized by milling or casting/annealing. The cast/annealed sample was found to have a low temperature magnetic moment that is 44% of the moment in the milled sample, which is consistent with theoretical predictions for ordering. Scanning transmission electron microscopy measurements were performed and the presence of ordered nano-domains in cast/annealed samples throughout the equiatomic NiFeCrCo HEA was identified.

  12. Optimizing Cr3+ concentration and evaluating energy transfer from Cr3+ to Nd3+ in Cr,Nd:GGG nanocrystals prepared by sol-gel method

    Institute of Scientific and Technical Information of China (English)

    Yassin Alshikh Mohamad∗; Yomen Atassi; Zafer Moussa

    2016-01-01

    Nanopowder of Cr:GGG and nanopowder of Cr,Nd:GGG with different concentrations of Cr3+ ranging from 0.1 at.% to 1.5 at.% were synthesized by the sol-gel method using acetic acid and ethylene glycol. Thermal gravimetric analysis and differential scanning calorimetry (TGA-DSC), X-ray diffraction (XRD) and photoluminescence spectroscopy were used to characterize the powder. The crystallite size was about 58 nm when treated at 1000 ºC for 2 h. Cr3+ photoluminescence spectrum in GGG showed a broad band emission around 730 nm. The intensity of this band decreased when co-doped with Nd, indicating an efficient energy transfer from Cr3+ to Nd3+. Photoluminescence intensity of Nd in Cr,Nd:GGG at 1.06μm showed that the optimum concentration of Cr3+ was about 1 at.% (more or less) for 1 at.% Nd3+. This result was also confirmed by chromium fluorescence decay rate analysis. Energy transfer efficiency was found to be about 84% for 1 at.% concentration of each chromium and neodymium.

  13. Defect compensation by Cr vacancies and oxygen interstitials in Ti4+-doped Cr2O3 epitaxial thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kaspar, Tiffany C.; Sushko, Petr; Bowden, Mark E.; Heald, Steve M.; Papadogianni, Alexandra; Tschammer, Carsten M.; Bierwagen, Oliver; Chambers, Scott A.

    2016-10-07

    Epitaxial thin films of Cr2-xTixO3 were deposited by oxygen-plasma-assisted molecular beam epitaxy (OPA-MBE) for 0.04 ≤ x ≤ 0.26. Ti speciation is verified by both x-ray photoelectron spectroscopy (XPS) and Ti K-edge x-ray absorption near-edge spectroscopy (XANES) to be Ti4+. Substitution of Ti for Cr in the corundum lattice is confirmed by modeling of the Ti K-edge extended x-ray absorption fine structure (EXAFS). Room temperature electrical transport measurements confirm the highly insulating nature of Ti-doped Cr2O3, despite the presence of aliovalent Ti4+. The resistivity of highly pure, undoped Cr2O3 was measured to be three orders of magnitude higher than for Ti-doped Cr2O3. Although the formation of Cr vacancies in Ti-doped Cr2O3 is found by density functional theory (DFT) calculations to be the energetically preferable defect compensation mechanism to maintain charge neutrality, an analysis of the XPS and EXAFS data reveal the presence of both Cr vacancies and oxygen interstitials at intermediate and high Ti concentrations, with a weak trend towards Cr vacancies as the Ti concentration increases. At low Ti concentrations, a strong dependence of the XPS Ti 2p core level peak width on concentration is observed. This dependence is attributed to the presence of widely spaced Ti dopants, which renders compensation of two or three Ti by a single oxygen interstitial or Cr vacancy, respectively, less probable. Instead, defect clusters of unknown type occur, although they may involve Cr vacancies. The defect compensation model developed here provides insight into previous, conflicting reports of n-type versus p-type conductivity in Ti-doped Cr2O3 at high temperature, and will inform future studies to exploit the wide variety of electronic and magnetic properties of corundum-structure oxides.

  14. Evaluation of hot corrosion protection of Cr-Al and CoNiCrAlY on IN-738LC

    Energy Technology Data Exchange (ETDEWEB)

    Khajavi, M.R. [Niroo Research Institute - Chemistry and Materials Research Center - Metallurgy Dept. End of Pounak-e-Bakhtari, P.O.Box 14665-517, Post Code 1468617151, Blvd., Shahrak-e-Gharb, Tehran (Iran)]|[Shiraz University - Materials Science and Engineering Department, Engineering School, Shiraz University, Shiraz (Iran); Pasha, A. [Niroo Research Institute - Chemistry and Materials Research Center - Metallurgy Dept. End of Pounak-e-Bakhtari, P.O.Box 14665-517, Post Code 1468617151, Blvd., Shahrak-e-Gharb, Tehran (Iran); Shariat, M.H. [Shiraz University - Materials Science and Engineering Department, Engineering School, Shiraz University, Shiraz (Iran)

    2004-07-01

    A program was conducted to evaluate the relative corrosion resistance of CoNiCrAlY and Chromium modified Aluminide on IN738-LC, used for turbine blades. The corrosion experiments were performed in a laboratory tube furnace. The microstructure of coatings was characterized by using optical and scanning electron microscopy techniques. The results indicated that at a temperature of 800 deg. C the CoNiCrAlY is more protective than Cr-Al coating. (authors)

  15. Effect of Cr Content on the Properties of Magnetic Field Processed Cr-Doped ZnO-Diluted Magnetic Semiconductors

    Directory of Open Access Journals (Sweden)

    Shiwei Wang

    2012-01-01

    Full Text Available Cr-doped ZnO-diluted magnetic semiconductor (DMS nanocrystals with various Cr contents were synthesized by hydrothermal method under high magnetic field. The result indicated that both the amount of Cr contents and high magnetic field significantly influenced crystal structure, morphology, and magnetic property of Cr-doped ZnO DMSs. When the Cr contents increased from 1 at% to 5 at%, the morphology of grains sequentially changed from flower-like to rod-like and then to the flake-like form. All the samples remained hexagonal wurtzite structure after Cr ions were doped into the ZnO crystal lattice. The Cr doping led to the increasing amount of defects and even enhanced the magnetic property of the matrix materials. All the Cr-doped ZnO DMSs obtained under high magnetic field exhibited obvious ferromagnetic behavior at room temperature. The results have also shown the successful substitution of the Cr3+ ions for the Zn2+ ions in the crystal lattice.

  16. Mechanical properties and microstructure of vaccum plasma sprayed Cr3C2 - 25(Ni20Cr) coatings

    OpenAIRE

    MRDAK MIHAILO R.

    2015-01-01

    This paper analyzes vacuum plasma spray VPS - Cr3C2 - 25(Ni20Cr) coatings. Commercial powder marked Sulzer Metco Woka 7205 is used. The powder is deposited with a plasma gun F4 at a distance of 340 mm from the substrate. The main objective of the study was to eliminate, at the reduced pressure of inert gas Ar, the degradation of primary Cr3C2 carbide into Cr23C6 carbide which significantly reduces the microhardness and mechanical properties of the coating. The coating is deposited with a thic...

  17. Effects of Cr and Ni on interdiffusion and reaction between U and Fe-Cr-Ni alloys

    Science.gov (United States)

    Huang, K.; Park, Y.; Zhou, L.; Coffey, K. R.; Sohn, Y. H.; Sencer, B. H.; Kennedy, J. R.

    2014-08-01

    Metallic U-alloy fuel cladded in steel has been examined for high temperature fast reactor technology wherein the fuel cladding chemical interaction is a challenge that requires a fundamental and quantitative understanding. In order to study the fundamental diffusional interactions between U with Fe and the alloying effect of Cr and Ni, solid-to-solid diffusion couples were assembled between pure U and Fe, Fe-15 wt.%Cr or Fe-15 wt.%Cr-15 wt.%Ni alloy, and annealed at high temperature ranging from 580 to 700 °C. The microstructures and concentration profiles that developed from the diffusion anneal were examined by scanning electron microscopy, and X-ray energy dispersive spectroscopy (XEDS), respectively. Thick U6Fe and thin UFe2 phases were observed to develop with solubilities: up to 2.5 at.% Ni in U6(Fe,Ni), up to 20 at.%Cr in U(Fe, Cr)2, and up to 7 at.%Cr and 14 at.% Ni in U(Fe, Cr, Ni)2. The interdiffusion and reactions in the U vs. Fe and U vs. Fe-Cr-Ni exhibited a similar temperature dependence, while the U vs. Fe-Cr diffusion couples, without the presence of Ni, yielded greater activation energy for the growth of intermetallic phases - lower growth rate at lower temperature but higher growth rate at higher temperature.

  18. Biosorption of Cr(III), Cr(VI), Cu(II) ions by intact cells of Spirulina platensis

    OpenAIRE

    Gelagutashvili, E.; Bagdavadze, N.; Rcheulishvili, A.

    2017-01-01

    The absorption characteristics of Cr(III), Cr(VI), Cu(II) ions on intact living cells Spirulina platensis (pH9.6) were studied by using a UV-VIS spectrophotometer. Also biosorption of these ions with cyanobacteria Spirulina platensis were studied using equilibrium dialysis and atomic absorption analysis.It was shown, that the absorption intensity of Spirulina platensis decreases, when Cr(III), Cr(VI), Cu(II) ions are added. Significant difference between the absorption intensity for Cu(II) Sp...

  19. Análisis crítico sobre la crítica audiovisual: de Bazin a Filmaffinity

    OpenAIRE

    BAS MUT, IRIS

    2012-01-01

    Se pretende analizar el mundo de la crítica audiovisual desde sus inicios hasta la actualidad trazando su evolución y momentos clave para intentar mostrar su utilidad e importancia. Se tendrán en cuenta los distintos tipos de textos críticos, dando cabida tanto a la crítica especializada de prestigio como a la crítica amateur, sobre todo la nacida desde la aparición de Internet y la consiguiente popularización de la cultura e información, trazando el arraigamiento de la cine...

  20. As(V), Cr(III) and Cr(VI) sorption on biochars and soil

    Science.gov (United States)

    Diamadopoulos, Evan; Agrafioti, Evita; Kalderis, Dimitrios

    2014-05-01

    The use of biochar, as a cost effective sorbent for heavy metal removal from contaminated water and soils is becoming a very promising practice. In this study, rice husk, the organic fraction of solid wastes, as well as sewage sludge were used as precursors for biochar production. The first was chosen as one of the most abundant types of biomass worldwide and the other two in order to find alternative innovative uses of these wastes. A series of batch kinetic and equilibrium (sorption and desorption) experiments was conducted using As(V), Cr(III) and Cr(VI) as adsorbates. The specific heavy metals were chosen in order to assess biochars removal capacity towards both anionic and cationic metals. Apart from biochars, a sandy loam soil was also used as adsorbent for metal removal. Knowing the separate behavior of biochars and soil towards metal sorption, it could be the first step in explaining the fate of heavy metals in a biochar amended soil. The kinetic study showed that, for all adsorbents and metals examined, sorption can be well described by the pseudo-second order kinetic model. What is more, simulation of sorption isotherms gave a better fit for the Freundlich model, possibly due to the heterogeneous surface of the initial biomasses and the fine aggregates that soil consists of. Based on the equilibrium study, the materials examined removed more than 95% of the initial Cr(III). This is possibly related to the electrostatic interactions between adsorbents negative surface charge and Cr(III) cations. However, removal rates for As(V) and Cr(VI) anions were significantly lower. Biochar derived from sewage sludge was efficient in removing 89% of Cr(VI) and 53% of As(V). Its ash high Fe2O3 content may have enhanced metal adsorption via precipitation. Soil was the most effective material for the removal of As(V), yet it could not strongly retain metal anions compared to biochars, as a significant amount of the adsorbed metal was released during desorption

  1. [CrIII(NCMe)6]3+--a labile CrIII source enabling formation of Cr[M(CN)6] (M=V, Cr, Mn, Fe) Prussian blue-type magnetic materials.

    Science.gov (United States)

    Nelson, Kendric J; Daniels, Matthew C; Reiff, William M; Troff, Shayla A; Miller, Joel S

    2007-11-26

    The kinetic inertness of the hexaaquachromium(III) (kH2O=2.4x10(-6) s(-1)) has led to challenges with respect to incorporating CrIII ions into Prussian blue-type materials; however, hexakis(acetonitrile)chromium(III) was shown to be substantially more labile (approximately 10(4) times) and enables a new synthetic route for the synthesis of these materials via nonaqueous solvents. The synthesis, spectroscopic, and physical properties of Cr[M(CN)6] (M=V, Cr, Mn, Fe) Prussian blue analogues synthesized from [CrIII(NCMe)6]3+ and the corresponding [MIII(CN)6]3- are described. All these compounds {(NEt4)0.02CrIII[VIII(CN)6]0.98(BF4)(0.08).0.10MeCN (1), CrIII[CrIII(CN)6].0.16MeCN (2), CrIII[MnIII(CN)6].0.10MeCN (3), and (NEt4)0.04CrIII0.64CrIV0.40[FeII(CN)6]0.40[FeIII(CN)6]0.60(BF4)(0.16).1.02MeCN (4)} are ferrimagnets exhibiting cluster-glass behavior. Strong antiferromagnetic coupling was observed for M=V, Cr, and Mn with Weiss constants (theta) ranging from -132 to -524 K; and in 2, where the strongest coupling is observed (theta=-524 K), the highest Tc (110 K) value was observed. Weak antiferromagnetic coupling was observed for M=Fe (theta=-12 K) leading to the lowest Tc (3 K) value in this series. Weak coupling and the low Tc value observed in 4 were additionally contributed by the presence of both [FeII(CN)6]4- and [FeIII(CN)6]3- as confirmed by 57Fe-Mössbauer spectroscopy.

  2. Protein expression on Cr resistant microorganism using electrophoresis method

    Directory of Open Access Journals (Sweden)

    SAJIDAN

    2009-01-01

    Full Text Available Fatmawati U, Suranto, Sajidan. 2009. Protein expression on Cr resistant microorganism using electrophoresis method. Nusantara Bioscience 1: 31-37. Hexavalent chromium (Cr(VI is known as toxic heavy metals, so the need is reduced to Cr(III is much less toxicity. Pseudomonas aeruginosa, Pseudomonas putida, Klebsiella pneumoniae, Pantoea sp. and Saccharomyces cerevisiae are resistant Cr(VI microorganism and have ability to reduce Cr(VI. The aim of this research is to know ability of microorganism to reduce Cr(VI and to know protein band pattern between Cr(VI resistant microorganism and non resistant microorganism which inoculated on LB broth. SDS-PAGE was used to indentify protein expression. While, Cr(VI concentration was identified by 1.5 diphenylcarbazide method. The quantitative data was analyzed by two factorial ANOVA that continued with DMRT at 1% level test. The qualitative data i.e. protein expression analyzed by relative mobility (Rf. The results showed that the ability of microorganisms to reduce Cr(VI at initial concentration of 0.5 ppm, 1 ppm, 5 ppm and 10 ppm may vary, the average percentage of the ability of each microorganism in reducing Cr(VI is P. putida (65% > S. cerevisiae (64.45% >. P. aeruginosa (60.73% > Pantoea sp. (50.22% > K. pneumoniae (47.82% > without microorganisms (34.25%. The adding microorganisms have significantly influenced toward reduction of Cr(VI. The SDS-PAGE shows that protein expression between resistant and not resistant microorganisms are no different, but resistant microorganisms have more protein (protein band is thicker.

  3. Crítica de Libros.

    Directory of Open Access Journals (Sweden)

    Fernando Colina Pérez

    1981-01-01

    Full Text Available

    PRESENTACION y ENSEÑANZAS DE SCHREBER, Daniel Paul Schreber -«Memorias de un Neurópata» -Ediciones Petrel. Buenos Aires -1978

    LA TEORIA COMO FICCION, Maud Mannoni -Editorial Crítica -1980

    MAS ALLA DE LA SOCIOLOGIA: EL GRUPO DE DISCUSION: TEORIA y CRITICA, Jesús Ibáñez -Ed. Siglo XXI -Madrid, 1979.

    LA SEXUALIDAD -Jean Laplanche

    EL ORDEN PSIQUIATRICO -Robert Castel -Ediciones La Piqueta. Madrid, 1980 -Colección «La Genealogía del Poder», dirigida por Julia Varela y Fernando Alvarez Uría

  4. Mito, crítica y gubernamentalidad

    Directory of Open Access Journals (Sweden)

    Alejandro Ruidrejo

    2013-07-01

    Full Text Available Partiendo de las proximidades y distancias reconocibles en los diagnósticos del presente ensayados por Adorno, Horkheimer y Foucault, se recuperará el modo en que cada uno de ellos asume la relación entre mito y crítica. Reconociendo el lugar central que la Aufklärung adquiere en el trabajo de estos pensadores, se señalará el modo en que se pone en cuestión la identificación de la modernidad con un proceso de secularización creciente. La pervivencia del mito expuesta en Dialéctica de la Ilustración encuentra su homólogo con la persistencia del poder pastoral concebido a partir de la cuestión de la gubernamentalidad occidental planteada por Michel Foucault.

  5. Magnetocaloric properties of Co/Cr superlattices

    Science.gov (United States)

    Mukherjee, Tathagata; Skomski, Ralph; Sellmyer, David; Binek, Christian

    2010-03-01

    Nanostructured materials aiming on refrigeration applications are experimentally realized by molecular beam epitaxial (MBE) growth of Co/Cr superlattices using mean-field theoretical concepts as guiding principles.footnotetextT. Mukherjee, S. Sahoo, R. Skomski, D. J. Sellmyer, and Ch. Binek, Phys. Rev. B 79, 144406-1-9 (2009). Magnetocaloric properties are deduced from measurements of the temperature and field dependence of the magnetization of our samples. More generally, the potential of artificial antiferromagnets for near room-temperature refrigeration is explored. The effects of intra-plane and inter-plane exchange interactions on the magnetic phase diagram in Ising-type model systems are revisited in mean-field considerations with special emphasis on tailoring magnetocaloric properties. The experimental results are discussed in light of our theoretical findings, and extrapolations for future improved nanostructures are provided. Financial support by NRI, and NSF through EPSCoR, Career DMR-0547887, and MRSEC.

  6. Studies of CR-39 etch rates

    CERN Document Server

    Rana, M A

    2002-01-01

    A series of chemical etching experiments have been carried out on CR-39 detectors irradiated with fission fragments of sup 2 sup 5 sup 2 Cf to study the bulk and track etching characteristics. Experimental data has been analyzed to find out important track etch parameters. Both bulk and track etch rates are found to follow the Arrhenius equation which gives the variation of etch rate with temperature for a specific set of etching conditions. Activation energies for bulk and track etching have been determined by fitting Arrhenius equation to the experimental data. Other track etch parameters, e.g. critical angle of etching and track registration efficiency have also been determined using experimental data. Track etch parameters depend on properties of incident ion and etching conditions. Results describing the dependence of track etch parameters on etching conditions have been presented. These results are useful in the interpretation of track data.

  7. Incontinencia y enfermedad crónica

    Directory of Open Access Journals (Sweden)

    Beatriz Sánchez-Herrera

    2013-01-01

    Full Text Available Explorar la producción y contenido de la información disponible a nivel mundial sobre el abordaje de la incontinencia urinaria (IU e incontinencia fecal (IF y su relación con la enfermedad crónica (EC. Materiales y métodos: a partir de una revisión de literatura en las bases de datos Cinahl, Ovid, Scielo, Medline y Psychoinfo, entre los años 2009 y 2012, bajo los descriptores de incontinencia urinaria e incontinencia fecal, en combinación con enfermedad crónica, con su traducción al inglés, se identificaron, analizaron y clasificaron los planteamientos sobre el tema de la incontinencia según relevancia para la comprensión de la misma en la situación de EC. Resultados: se presentan los estudios encontrados clasificados en cinco grandes grupos sobre IU e IF que incluyen los que ilustran la magnitud del problema por su frecuencia y tipología, los que establecen relación directa entre la incontinencia y la EC, los que describen otros factores asociados con la incontinencia y con la EC, los que abordan la forma de valorar la incontinencia y los que dan aportes respecto al manejo de la IU o IF en la EC. Conclusiones: la literatura tiene abundante producción científica en sus dos últimos años y a nivel mundial sobre la IU pero no en igual proporción sobre la IF. Existen modelos para la valoración, medición y comprensión del fenómeno así como para la intervención y atención puntual sobre la misma. No se reportan abordajes integrales al problema de la IU e IF en personas con EC.

  8. Meningococcemia crónica Chronic menigococcemia

    Directory of Open Access Journals (Sweden)

    Jorge V. Martínez

    2008-08-01

    Full Text Available La meningococcemia crónica es una forma clínica infrecuente dentro del espectro de infecciones producido por Neisseria meningitidis. Clásicamente esta forma clínica se caracteriza por fiebre, lesiones cutáneas, compromiso articular, y desarrollo en hemocultivo de la bacteria responsable, habitualmente con ausencia de compromiso meníngeo. Generalmente afecta a adultos jóvenes previamente sanos. Se desconoce la razón por la cual estos pacientes, a diferencia de los que presentan meningitis aguda por Neisseria meningitidis y meningococcemia aguda, pueden sobrevivir sin complicaciones durante semanas en ausencia de tratamiento antibiótico útil. Se ha planteado que debido a la alta sensibilidad de esta bacteria a los antibióticos beta-lactámicos, muchos casos podrían ser tratados inadvertidamente. Describimos un caso de meningococcemia crónica en una mujer joven que presenta un cuadro clásico no reconocido inicialmente.Chronic meningococcemia is an unfrequent clinical picture within the spectrum of infections produced by Neisseria meningitidis. It is classically characterized by fever, skin lesions and joint involvement, usually without meningeal involvement, and with blood culture growth of the responsible bacteria. It generally affects previously healthy young people. It is unknown why these patients, unlike patients with Neisseria meningitidis’s acute meningitis and with acute meningococcemia, can survive without complications during weeks, in abscence of an useful antibiotic treatment. It has been hypothesized that owing to high susceptibility to beta-lactam antibiotics of Neisseria meningitidis, many cases may be treated inadvertently. We describe a case of chronic meningococcemia in a young woman who presented a classical clinical picture, not recognized initially.

  9. Evaluating the corrosion resistance of UBM-deposited Cr/CrN multilayers

    Directory of Open Access Journals (Sweden)

    Yuri Lizbeth Chipatecua Godoy

    2011-05-01

    Full Text Available This work was aimed at evaluating the corrosion resistance of multilayer Cr/CrN coatings deposited by the unbalan-ced magnetron sputtering (UBM technique. Coatings were produced at room temperature using 400 mA discharge current, 9 sccm argon flow and 3 sccm nitrogen flow. The total thickness of coatings deposited on AISI 304 stainless steel and silicon (100 varied between 0.2 a 3 μm as bilayer period varied between 20 and 200 nm. Coating microstructure and chemical composition was stu-died through scanning electron microscopy (SEM and tex-ture and crystalline phases were analysed by X-ray diffraction (XRD before and after corrosion tests which were carried out by potentiodynamic polarisation using 0.5 M H2SO4 + 0.05M KSCN solution. Lower bilayer period coatings presented better corrosion resistance and their corrosion mechanism is discussed in this article.

  10. Wear resistance of a Cr3C2-NiCr detonation spray coating

    Science.gov (United States)

    Wang, Jun; Wang, Jun; Sun, Baode; Guo, Qixin; Nishio, Mitsuhiro; Ogawa, Hiroshi

    2002-06-01

    Coatings can be applied to surfaces to improve the surface characteristics over those of the bulk properties and are widely used in tribological applications either to reduce wear and/or to modify friction during contact. One of the foremost coating methods for combating wear is thermal spraying. To prolong the life of steel slab continuous casting rolls, Cr3C2-NiCr detonation spray coating was processed on the roll surface in a steelmaking plant in China. This article studies the mechanical properties and wear resistance of this coating. The abrasive and dry frictional wear testing were performed using a pin-on-disk tester. Experimental results show that the wear resistance of the coated samples, i.e., coating reduces the risk of seizure compared to uncoated samples, is much better than those of the uncoated steel at room and elevated temperatures with any load and sliding velocity. The coating wear mechanisms under different test conditions are discussed.

  11. Evaluation du crédit-bail et risque de crédit

    OpenAIRE

    Capiez, Alain

    2000-01-01

    International audience; Malgré une similitude observée entre les contrats de leasing et les obligations à risque, les modèles classiques de détermination des loyers d'un contrat de crédit-bail se focalisent sur le risque attaché au matériel ou risque de valeur résiduelle et ignorent le risque de crédit. Nous comparons les différents modèles existants et privilégions un modèle moderne qui adopte une approche unifiée en intégrant les deux types de risque et leur interaction.

  12. Thermoluminescence dosimetry in quality imaging in CR mammography systems

    Energy Technology Data Exchange (ETDEWEB)

    Gaona, E.; Franco E, J.G. [UAM-Xochimilco, 04960 Mexico D.F. (Mexico); Azorin N, J. [UAM-Iztapalapa, 09340 Mexico D.F. (Mexico); Diaz G, J.A.I. [CICATA, Unidad Legaria, Av. Legaria 694, 11599 mexico D.F. (Mexico); Arreola, M. [Department of Radiology, Shands Hospital at UF, PO Box 100374, Gainesville, FL 32610-0374 (United States)

    2006-07-01

    The aim of this work is to estimate the average glandular dose with Thermoluminescence Dosimetry (TLD) and comparison with quality imaging in CR mammography. For measuring dose, FDA and ACR use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, Full Field Digital Mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one CR mammography system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium fluoro halide. We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated x-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose that overcomes 3.0 mGy and it doesn't improve the image quality and dose to the breast will be excessive. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement. (Author)

  13. Anelasticity in Fe-Al-Cr alloys at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Golovin, I.S., E-mail: i.golovin@misis.ru [Physics of Metals Department, National University ' Moscow Institute of Steel and Alloys' , Moscow (Russian Federation); Physics of Metals Department and Materials Science, Tula State University, Tula (Russian Federation); Riviere, A. [LMPM-UMR CNRS 6617, ENSMA, F-86961 Futuroscope Chasseneuil Cedex (France)

    2009-09-15

    Several (Fe,Cr){sub 3}Al alloys with Cr content from 3 to 25% have been studied in the temperature range from 680 to 930 K using isothermal frequency dependent tests (from 10{sup -4} to 10{sup 2} Hz). Three relaxation peaks were observed in this range. The Zener relaxation (P1 peak) caused by reorientation of pairs of substitute atoms in Fe is observed in all studied alloys and used to evaluate the activation parameters of substitute atom jumps in Fe. Activation parameters of the Zener peak in Fe-26Al-Cr depend not too much on Cr content (H = 275-290 kJ/mol, {tau}{sub 0} = 10{sup -19} to 10{sup -20} s), while the relaxation strength increases with the increase in Al + Cr content. The second internal friction peak (P2) at higher temperatures with similar activation energies but higher {tau}{sub 0} (10{sup -17} to 10{sup -19} s) is observed only in Cr containing alloys but not in Fe-25Al binary alloy. Most probably this peak is controlled by dislocations motion in Fe-26Al-Cr alloys. The third peak, denoted as P3 (H = 428 kJ/mol, {tau}{sub 0} = 10{sup -25} s), was observed only in the Fe-25Al-25Cr alloy and was classified as a grain boundary peak.

  14. Microcosm investigation on phytoremediation of Cr using Azolla pinnata.

    Science.gov (United States)

    Rai, Prabhat Kumar

    2010-01-01

    The extent of Chromium (Cr) pollution in Singrauli industrial region, India was assessed and phytoremediation capacity of a small water fern, Azolla pinnata R.BR (Azollaceae) was observed to purify waters polluted by Cr under microcosm condition. Azolla pinnata endemic to India is a potential hyper-accumulator of heavy metals. During 13 days of the experiment the fern was grown in the aqueous medium containing Cr3+ and CrO4(2-) ions, each in a concentration 0.5, 1.0, and 3.0 mg L(-1). The presence of these ions caused a + 3.1 to -37.5% inhibition of Azolla pinnata growth in comparison to the control. After 13 days of the experiment, metal contents in the solution was decreased up to 70% (CrO4(2-) 3.0 mg L(-1) treatment) to 88% (CrO4(2-) 0.5 mg L(-1) treatment). In the Azolla pinnata tissues, the concentration of couple of the ionic forms of Cr under investigation ranged from 415 to 1095 mg kg(-1) dry mass (dm); the highest level being found for Cr (III) containing solution.

  15. Cr:ZnSe planar waveguide mid-IR laser

    Science.gov (United States)

    Willimas, J. E.; Martyshkin, D. V.; Fedorov, V. V.; Moskalev, I. S.; Camata, R. P.; Mirov, S. B.

    2011-02-01

    Middle infrared (mid-IR) chromium-doped zinc selenide (Cr:ZnSe) bulk lasers have attracted a lot of attention due to their unique combination of optical and laser properties facilitating a wide range of potential scientific, industrial, and medical applications. Utilization of thin film waveguide geometry enabling good thermal management and control of beam quality is a viable pathway for compact chip-integrated optical laser design. Cr:ZnSe thin films are also promising as saturable absorbers and mode-lockers of the cavities of solid state lasers operating over 1.3-2.1 μm. We recently reported the first successful demonstration of mid-IR Cr:ZnSe planar waveguide lasing at 2.6 μm under gain-switched short-pulse (5 ns) 1.56 μm excitation as well as the passive Q-switching of the cavity of a fiber-pumped Er:YAG laser operating at 1645 nm using a highly doped Cr:ZnSe thin film. PLD grown Cr:ZnSe waveguide were fabricated on sapphire substrates (Cr:ZnSe/sapphire) with chromium concentration of 1018-1019 cm-3. Further development of mid-IR lasing in the Cr:ZnSe planar waveguide under continuous wave excitation were investigated. In addition, deposition of Cr:ZnSe-based thin film structures on n-type GaAs substrates were also investigated for possible mid-IR electroluminescence.

  16. Thermoluminescence dosimetry in quality imaging in CR mammography systems

    Energy Technology Data Exchange (ETDEWEB)

    Gaona, E.; Franco E, J.G. [UAM-Xochimilco, 04960 Mexico D.F. (Mexico); Azorin N, J. [UAM-Iztapalapa, 09340 Mexico D.F. (Mexico); Diaz G, J.A.I. [CICATA, Unidad Legaria, Av. Legaria 694, 11599 mexico D.F. (Mexico); Arreola, M. [Department of Radiology, Shands Hospital at UF, PO Box 100374, Gainesville, FL 32610-0374 (United States)

    2006-07-01

    The aim of this work is to estimate the average glandular dose with Thermoluminescence Dosimetry (TLD) and comparison with quality imaging in CR mammography. For measuring dose, FDA and ACR use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, Full Field Digital Mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one CR mammography system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium fluoro halide. We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated x-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose that overcomes 3.0 mGy and it doesn't improve the image quality and dose to the breast will be excessive. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement. (Author)

  17. Effect of genotype, Cr(III and Cr(VI on plant growth and micronutrient status in Silene vulgaris (Moench

    Directory of Open Access Journals (Sweden)

    A. E. Pradas-del-Real

    2013-06-01

    Full Text Available Chromium released into the environment from industrial activities has become an important environmental concern. Silene vulgaris has been proven to be tolerant to many heavy metals, so it is considered an interesting species in the revegetation and restoration of polluted soils, but no information is available about its response to Cr. The objective of this work was to study uptake and influence on plant growth of Cr(III and Cr(VI in six genotypes (four hermaphrodites and two females of S. vulgaris from different sites of Madrid (Spain. Plants were treated for 12 days with 60 µM of Cr(III or Cr(VI in semihydroponics. Dry weights, soil-plant analysis development values (SPAD reading with chlorophylls and micronutrient and total Cr concentrations were determined. Metal uptake was higher in presence of Cr(VI than of Cr(III and poorly translocated to the shoots. In both cases S. vulgaris did not show visual toxicity symptoms, biomass reduction, or differences among SPAD values as consequence of Cr additions. However genotypes SV36 and SV38 showed Fe and Mn imbalance. This is the first report on the relatively good performance of hermaphrodite and female S. vulgaris genotypes in Cr uptake and physiological traits, but further studies will be necessary to elucidate the mechanisms by which the gender may influence these variables. S. vulgaris presented high diversity at genotypic level; the treatment with hexavalent Cr increased the differences among genotypes so the use of cuttings from an homogeneous genotype seems to be an adequate method for the study of this species.

  18. Reduction of Cr(VI) to Cr(III) using silicon nanowire arrays under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Fellahi, Ouarda [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique-CRTSE 02, Bd Frantz Fanon, BP. 140, Alger 7 Merveilles (Algeria); Barras, Alexandre [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Pan, Guo-Hui [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Dong Nanhu Road, Changchun 130033 (China); Coffinier, Yannick [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Hadjersi, Toufik [Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique-CRTSE 02, Bd Frantz Fanon, BP. 140, Alger 7 Merveilles (Algeria); Maamache, Mustapha [Laboratoire de Physique Quantique et Systèmes Dynamiques, Département de Physique, Université de Sétif, Sétif 19000 (Algeria); Szunerits, Sabine [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); and others

    2016-03-05

    Highlights: • Cr(VI) reduction to Cr(III) using silicon nanowires decorated with Cu nanoparticles. • The reduction takes place at room temperature and neutral pH under visible light. • The photocatalytic reduction was enhanced by addition of adipic or citric acid. - Abstract: We report an efficient visible light-induced reduction of hexavalent chromium Cr(VI) to trivalent Cr(III) by direct illumination of an aqueous solution of potassium dichromate (K{sub 2}Cr{sub 2}O{sub 7}) in the presence of hydrogenated silicon nanowires (H-SiNWs) or silicon nanowires decorated with copper nanoparticles (Cu NPs-SiNWs) as photocatalyst. The SiNW arrays investigated in this study were prepared by chemical etching of crystalline silicon in HF/AgNO{sub 3} aqueous solution. The Cu NPs were deposited on SiNW arrays via electroless deposition technique. Visible light irradiation of an aqueous solution of K{sub 2}Cr{sub 2}O{sub 7} (10{sup −4} M) in presence of H-SiNWs showed that these substrates were not efficient for Cr(VI) reduction. The reduction efficiency achieved was less than 10% after 120 min irradiation at λ > 420 nm. Addition of organic acids such as citric or adipic acid in the solution accelerated Cr(VI) reduction in a concentration-dependent manner. Interestingly, Cu NPs-SiNWs was found to be a very efficient interface for the reduction of Cr(VI) to Cr(III) in absence of organic acids. Almost a full reduction of Cr(VI) was achieved by direct visible light irradiation for 140 min using this photocatalyst.

  19. 新型Cr-Ni-Mo和Cr-Ni-Co堆焊合金空蚀性能%Cavitation Erosion Resistance of Novel Cr-Ni-Mo and Cr-Ni-Co Overlaying Alloys

    Institute of Scientific and Technical Information of China (English)

    徐桂芳; 秦敏明; 雷玉成; 陈希章; 李涛

    2012-01-01

    New type Cr-Ni-Mo and Cr-Ni-Co overlaying alloys were prepared by argon tungsten-arc welding (TIG) on 304 stainless steel, and tested by cavitation vibrating device. The cavitation erosion resistance of alloys was compared through the analysis of mass loss. The alloy layer was analyzed by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and microhardness tester. Results indicate that the cavitation erosion resistance of Cr-Ni-Mo and Cr-Ni-Co overlaying alloys is better than that of 304 stainless steel, and the resistance of Cr-Ni-Co is better than Cr-Ni-Mo. In the process of cavitation the damage is preferred to appear in grain boundary. Phase transformation from austenite to martensite happens in the cavitation process of Cr-Ni-Co alloy, and it is helpful to absorb the energy and delay the process of cavitation erosion, and enhance the cavitation erosion resistance effectively. The cavitation erosion resistance of overlaying alloys is related to hardness and work hardening ability.%采用钨极氩弧焊(TIG)将新型Cr-Ni-Mo和Cr-Ni-Co合金堆焊于304不锈钢表面进行空蚀试验,通过失重比较不同合金的抗空蚀性能.采用扫描电镜(SEM)、X射线衍射(XRD)仪和显微硬度计对合金层进行分析.结果表明:Cr-Ni-Mo和Cr-Ni-Co合金的耐空蚀性能均优越于304不锈钢,其中Cr-Ni-Co优于Cr-Ni-Mo;空蚀破坏优先出现在堆焊层的晶界处;Cr-Ni-Co合金在空蚀过程中发生了因奥氏体向马氏体的转变,有利于能量吸收,延缓了空蚀的进行,提高其耐空蚀性能;堆焊合金的抗空蚀能力与合金本身的硬度和加工硬化能力有关.

  20. Magnetic properties and hyperfine interactions in Cr8, Cr7Cd, and Cr7Ni molecular rings from 19F-NMR

    Science.gov (United States)

    Bordonali, L.; Garlatti, E.; Casadei, C. M.; Furukawa, Y.; Lascialfari, A.; Carretta, S.; Troiani, F.; Timco, G.; Winpenny, R. E. P.; Borsa, F.

    2014-04-01

    A detailed experimental investigation of the 19F nuclear magnetic resonance is made on single crystals of the homometallic Cr8 antiferromagnetic molecular ring and heterometallic Cr7Cd and Cr7Ni rings in the low temperature ground state. Since the F- ion is located midway between neighboring magnetic metal ions in the ring, the 19F-NMR spectra yield information about the local electronic spin density and 19F hyperfine interactions. In Cr8, where the ground state is a singlet with total spin ST = 0, the 19F-NMR spectra at 1.7 K and low external magnetic field display a single narrow line, while when the magnetic field is increased towards the first level crossing field, satellite lines appear in the 19F-NMR spectrum, indicating a progressive increase in the Boltzmann population of the first excited state ST = 1. In the heterometallic rings, Cr7Cd and Cr7Ni, whose ground state is magnetic with ST = 3/2 and ST = 1/2, respectively, the 19F-NMR spectrum has a complicated structure which depends on the strength and orientation of the magnetic field, due to both isotropic and anisotropic transferred hyperfine interactions and classical dipolar interactions. From the 19F-NMR spectra in single crystals we estimated the transferred hyperfine constants for both the F--Ni2+ and the F--Cd2+ bonds. The values of the hyperfine constants compare well to the ones known for F--Ni2+ in KNiF3 and NiF2 and for F--Cr3+ in K2NaCrF6. The results are discussed in terms of hybridization of the 2s, 2p orbitals of the F- ion and the d orbitals of the magnetic ion. Finally, we discuss the implications of our results for the electron-spin decoherence.

  1. Growth and characterization of YAG:Cr4+epitaxial films

    Science.gov (United States)

    Ubizskii, Sergii B.; Syvorotka, Igor M.; Melnyk, Sergii S.; Matkovskii, Andrej O.; Kopczynski, Krzysztof; Mierczyk, Zygmunt; Frukacz, Zygmunt

    1999-03-01

    Epitaxial films with thickness of 10 - 250 micrometers of yttrium aluminum garnet (YAG) doped with Cr were grown by liquid phase epitaxy technique on YAG:Nd substrates. Co-doping with Mg2+ is used to force the Cr4+ valent state formation. Dependence of absorption spectra of obtained films on melt-solution composition, growth conditions and thermal treatment in reducing and oxidizing atmospheres is studied. A very intensive absorption band in UV region with maximum at 275 nm was found both in co-doped and YAG:Mg2+ epifilms caused probably by oxygen vacancies compensating the excess charge of Mg2+. Its intensity correlates with Cr4+ content in the film in that way: it decreases with Cr4+ entering in the film. The absorption being characteristic for YAG:Cr4+ crystals is found in co-doped films grown at higher temperatures (1000 - 1100 degree(s)C). The processes occurring during annealing are discussed.

  2. Theoretical model of CR Forbush-decrease and precursors effects

    Science.gov (United States)

    Lev, Dorman

    The understanding of the mechanism of CR Forbush decrease and precursor effects is important for forecasting of the great magnetic storms by using on-line one hour CR observation data. We consider in details the situation with CR distribution inside CME and how it changed with time. We suppose that shock wave before CME is semi-transpired and the coefficient of transparence depends from the CR particles rigidity. One differential equation determined the change of CR intensity inside CME by the particle energy decrease in the expanding volume and by exchange with CR particles outside the CME. The other differential equation determined the outside CR particles drift acceleration by interaction with the shock wave before CME (this effect gives increase of CR intensity before magnetic storm sudden commencement) as well as exchange with CR particles inside the CME along the IMF lines (what gives the decrease of CR intensity before the start of magnetic storm on the Earth). We calculate also the expected CR anisotropy. Obtained results we compare with observation data. It is obvious now that according to data from the past on big variations of planetary surface temperature on scales of many millions and thousands of years, the Earth’s global climate change is determined mostly by space factors, including: the moving of the Solar system around the center of our galaxy, the crossing of galactic arms and molecular dust clouds, nearby supernova and supernova remnants. Another important space factor is the cyclic variations of solar activity and the solar wind (mostly on the scale of hundreds of years and decades). The effects of space factors on the Earth’s climate are realized mostly through cosmic rays (CR) and space dust influencing the formation of clouds, thereby controlling the total energy input from the Sun into the Earth’s atmosphere. The propagation and modulation of galactic CR (generated mostly during supernova explosions and in supernova remnants in our

  3. Spin magnetic moments from single atoms to small Cr clusters

    Energy Technology Data Exchange (ETDEWEB)

    Boeglin, C.; Decker, R.; Bulou, H.; Scheurer, F.; Chado, I. [IPCMS-GSI - UMR 7504, 67037 Strasbourg Cedex (France); Ohresser, P. [LURE, 91405 Orsay (France); Dhesi, S.S. [ESRF, BP 220, 38043 Grenoble Cedex (France); Present permanent address: Diamond Light Source, Chilton, Didcot OX11 0QX (United Kingdom); Gaudry, E. [LMCP, 4, place Jussieu, 75252 Paris (France); Lazarovits, B. [CCMS, T.U. Vienna, Gumpendorfstr. 1a, 1060 Wien (Austria)

    2005-07-01

    Morphology studies at the first stages of the growth of Cr/Au(111) are reported and compared to the magnetic properties of the nanostructures. We analyze by Scanning Tunneling Microscopy and Low Energy Electron Diffraction the Cr clusters growth between 200 K and 300 K. In the early stages of the growth the morphology of the clusters shows monoatomic high islands located at the kinks of the herringbone reconstructed Au(111) surface. By X-ray Magnetic Circular Dichroism performed on the Cr L{sub 2,3} edges it is shown that the temperature dependent morphology strongly influences the magnetic properties of the Cr clusters. We show that in the sub-monolayer regime Cr clusters are antiferromagnetic and paramagnetic when the size reaches the atomic limit. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Preferential dissolution behaviour in Ni–Cr dental cast alloy

    Indian Academy of Sciences (India)

    Viswanathan S Saji; Han Cheol Choe

    2010-08-01

    A Ni–Cr–Mo dental alloy was fabricated by three different casting methods, viz. centrifugal casting, high frequency induction casting and vacuum pressure casting. The dependence of cast microstructure on the electrochemical corrosion behaviour was investigated using potentiodynamic cyclic and potentiostatic polarization techniques, impedance spectroscopy and scanning electron microscopy. The experimental results were compared and discussed with those obtained for a Co–Cr–Mo counterpart. The results of the study showed that the variation in casting morphologies with casting methods has only marginal influence in the overall corrosion resistance of Ni–Cr and Co–Cr dental alloys. There was severe preferential dissolution of Ni rich, Cr and Mo depleted zones from the Ni–Cr–Mo alloy. The overall corrosion resistance property of the Co–Cr base alloy was better than that of the Ni–Cr base alloy.

  5. The pupil is faster than the corneal reflection (CR): are video based pupil-CR eye trackers suitable for studying detailed dynamics of eye movements?

    NARCIS (Netherlands)

    Hooge, I.T.C.; Holmqvist, K.; Nyström, Marcus

    2016-01-01

    Most modern video eye trackers use the p-CR (pupil minus CR) technique to deal with small relative movements between the eye tracker camera and the eye. We question whether the p-CR technique is appropriate to investigate saccade dynamics. In two experiments we investigated the dynamics of pupil, CR

  6. Reduction of Cr(VI) and survival in Cr-contaminated sites by Caulobacter crescentus

    Science.gov (United States)

    Hu, P.; Chakraborty, R.; Brodie, E. L.; Andersen, G. L.; Hazen, T. C.

    2008-12-01

    The Caulobacter spp. is known to be able to live in low-nutrient environments, a characteristic of most heavy metal-contaminated sites. Recent studies have shown that Caulobacter crescentus can grow in chemically defined medium containing up to 1 mM uranium. Whole-genome transcriptional analysis and electron microscopic imaging of heavy metal stresses in Caulobacter crescentus also provided insight and evidence that the bacterium used an array of defensive mechanisms to deal with heavy metal stresses. In addition to up-regulated enzymes protecting against oxidative stress, DNA repair and down-regulated potential chromium transport, one of the major gene groups respond to chromium stress is "electron transport process and cytochrome oxidases", including cytochrome c oxidases, raising the possibility that the cells can employ the cytochromes to reduce chromium. Analysis of the microbial community at the chromium contaminated DOE site at Hanford, WA revealed the presence of Caulobacter spp. As an oligotroph, Caulobacter can play a significant role in chromium reduction in the environment where the nutrients are limited. This result was confirmed by both 16S rDNA based microarray (Phylochip) as well as by MDA-based clone library data. Based on these results we further investigated the capability of this organism to reduce Cr(VI) using the well known model strain Caulobacter crescentus CB15N. Preliminary cell suspension experiments were set up with glucose as the electron donor and Cr(VI) as the electron acceptor in phosphate based M2 salts buffer. After 22 hours almost 27% of Cr(VI) was reduced in the incubations containing active cells relative to the controls containing heat killed cells. Also, in another set of controls with no electron acceptor added, cells showed no increase in cell density during that time demonstrating that the reduction of Cr(VI) by cells of Caulobacter was due to biological activity. Future experiments will investigate the components

  7. Introduction of Hydrogen Peroxide as an Oxidant in Flow Injection Analysis: Speciation of Cr(III) and Cr(VI)

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    1998-01-01

    Hydrogen peroxide was used as an oxidant in Flow Injection Analysis (FIA). The formation of gaseous components during the analysis was suppressed by maintaining a concentration lower than 0.15% of hydrogen peroxide in 0.1 M NaOH. By this method Cr(III) was oxidised on-line to Cr(VI) which...

  8. Large magneto-optical effect in low-temperature-grown GaCrN and GaCrN:Si

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Y.K.; Fan, P.H.; Emura, S.; Hasegawa, S.; Asahi, H. [Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2012-03-15

    GaCrN layers were grown at 300 and 100 C by radio-frequency plasma-assisted molecular-beam epitaxy on sapphire substrates. X-ray diffraction results showed no obvious secondary phase in the GaCrN samples grown at 300 C with Cr concentration even up to 9%. A very sharp line was found at 356 nm in the photoluminescence spectra below 50 K, which comes from high crystalline quality regions in the GaCrN layers. All the samples grown at low temperatures exhibited ferromagnetic characteristics. Si-doped GaCrN with Cr concentration of 6% has the largest saturation magnetization. Magnetic circular dichroism (MCD) measurement was performed for these samples at 10 K to investigate magneto-optical effect. Large magneto-optical effect was confirmed in the low-temperature-grown non-doped and Si-doped GaCrN. Zeeman splitting was enhanced by Si-doping in the low-temperature-grown GaCrN (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Annealing effect on the structural and optical properties of Cr/ -Cr2O3 monodispersed particles based solar absorbers

    CSIR Research Space (South Africa)

    Khamlich, S

    2013-01-01

    Full Text Available A cost-effective and environmentally friendly green chemical method, the so-called aqueous chemical growth (ACG) method, was used to deposit chromium/alpha-chromium(III) oxide, Cr/a-Cr2O3, monodispersed particles, for solar absorbers applications...

  10. Ferromagnetic resonance studies and magnetization curvesof Co-Cr and Co-Cr/Ni-Fe thin films

    NARCIS (Netherlands)

    Stam, Maria Theresia Helena Clasina Wilhelmina

    1989-01-01

    In this thesis CoCr and CoCr/NiFe double layers are studied by ferromagnetic resonance. The coercivity and the initial susceptibility of these layers are measured. An approximation of the Kooy and Enz model which is suitable for calculating the initial suceptibility is presented [3.36]. A theoretica

  11. Cr-Bearing Inclusions in IVA Irons: Implication for Cr and Volatile Behaviors in the Metallic Cores

    Science.gov (United States)

    Isa, J.; McKeegan, K. D.; Wasson, J. T.

    2015-07-01

    We found inclusions that contribute to bulk Cr concentrations and found fO2 or fS2 changes during crystallization. O-isotope compositions of chromite are mass-dependently lighter than other IVA oxides. Also, we discovered a new mineral MnCr2S4.

  12. con enfermedad crónica

    Directory of Open Access Journals (Sweden)

    María del Refugio Zavala Rodríguez

    2007-01-01

    Full Text Available El propósito del estudio fue determinar el grado de correlación entre los niveles de fortaleza para la salud y de ansiedad-rasgo, en unamuestra de 200 pacientes integrada por medio de muestreo no probabilístico; los criterios de inclusión fueron: adultos de ambos génerosdiagnosticados con enfermedad crónica, con estudios de enseñanza básica y orientada. El marco teórico que guió la investigación es elModelo de Adaptación de Roy. El diseño fue descriptivo, transversal, correlacional. Se utilizó el cuestionario de fortaleza de S. Pollock y laescala de autoevaluación de ansiedad-rasgo de Spielberger; los instrumentos presentaron una consistencia interna aceptable con unAlpha de Cronbach de ,852 y ,813 respectivamente. La información se recabó de cuatro instituciones de salud ubicadas en los municipiosde Tampico-Cd. Madero Tamaulipas, México. El análisis de los datos se efectuó mediante estadística descriptiva e inferencial, se utilizó elpaquete estadístico SPSS versión 13. El rango de edad que predominó fue de 45 a 64 años (54%; el 55% fue del sexo femenino, el 48%cuenta con estudios de primaria, cerca del 90% padece de una enfermedad metabólica. El coeficiente de correlación de Spearman entrela fortaleza para la salud y la ansiedad-rasgo fue significativo (Œ,570, valor Œp,000. En la mayoría de la población participante se encontróun nivel moderado tanto de fortaleza (83% como de ansiedad (73%. El análisis de regresión múltiple indicó que la relación significativaentre estas dos variables no es afectada por la edad, el género o los años de evolución de la enfermedad crónica. Los datos de este estudiomuestran evidencia de que en los pacientes con enfermedades crónicas a mayor nivel de fortaleza menor nivel de ansiedad-rasgo. Estasituación invita a desarrollar más estudios de estos fenómenos, en la disciplina de enfermería, que sirvan como sustento teórico-prácticopara el diseño o la mejora de

  13. Development of the dentistry alloy Ni-Cr-Nb; Desenvolvimento de ligas odontologicas Ni-Cr-Nb

    Energy Technology Data Exchange (ETDEWEB)

    Souza, M.A.; Ramos, A.S.; Hashimoto, T.M., E-mail: mari_sou@hotmail.co [UNESP/FEG, Guaratingueta, SP (Brazil). Fac. de Engenharia. Dept. de Materiais e Tecnologia

    2010-07-01

    This work reports on the structural characterization of Ni-Cr-Mo and Ni-Cr-Nb alloys produced by arc melting. Samples were characterized by means of optical microscopy, X-ray diffraction, scanning electron microscopy, and EDS analysis. Results indicated that the arc melting process was efficient to produce homogeneous structures in Ni-Cr-Mo and Ni-Cr-Nb alloys. The nickel dissolved large amounts of Cr, Mo and Nb, which was detected by EDS analysis and X-ray diffraction. The alloy containing molybdenum indicated the presence of structure based on Ni{sub SS}, while that the alloys containing niobium presented primary grains of Ni{sub SS} and precipitates formed by the simultaneous transformation of the Ni and Ni{sub 3}Nb phases. (author)

  14. Improvement on Simultaneous Determination of Cr(III) and Cr(VI) by Capillary Electrophoresis and Chemiluminescence Detection

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A sensitive method for the simultaneous determination of Cr(III) and Cr(VI) using in-capillary reaction capillary electrophoresis separation and chemiluminescence detection was developed. The procedures were designed as follows: The sample, hydrochloric acid and sodium hydrogen sulfite solution segments were injected sequentially into the capillary. The reaction of Cr(VI) reduced to Cr(III) by HSO3- occurred inside the capillary after applying the running voltage. According to the migration time difference of both Cr(III) ions moving towards to the cathode (detection end), they could be separated and determined. The limits of detection for chromium(III) and chromium(VI) (S/N = 3) were 6.0(10-13 mol/L (12 zmol) and 1.9(10-11 mol/L (380 zmol), respectively.

  15. Better Living through Chemistry: Caloric Restriction (CR) and CR Mimetics Alter Genome Function to Promote Increased Health and Lifespan

    Science.gov (United States)

    Gillespie, Zoe E.; Pickering, Joshua; Eskiw, Christopher H.

    2016-01-01

    Caloric restriction (CR), defined as decreased nutrient intake without causing malnutrition, has been documented to increase both health and lifespan across numerous organisms, including humans. Many drugs and other compounds naturally occurring in our diet (nutraceuticals) have been postulated to act as mimetics of caloric restriction, leading to a wave of research investigating the efficacy of these compounds in preventing age-related diseases and promoting healthier, longer lifespans. Although well studied at the biochemical level, there are still many unanswered questions about how CR and CR mimetics impact genome function and structure. Here we discuss how genome function and structure are influenced by CR and potential CR mimetics, including changes in gene expression profiles and epigenetic modifications and their potential to identify the genetic fountain of youth. PMID:27588026

  16. Properties of CuCr contact materials with low chromium content and fine particles

    Institute of Scientific and Technical Information of China (English)

    曹辉; 王亚平; 郑志; 冼爱平

    2003-01-01

    The voltage withstanding capability and electric conductivity of CuCr contact materials with low chromium content and fine Cr particles were studied. The results show that the withstanding voltage has little relation with the Cr content for the melted-casting CuCr alloy within 15%-29% Cr content, and that the electric conductivity of the alloy increases with the decreasing of Cr content.

  17. Electroplating process of amorphous Fe-Ni-Cr alloy

    Institute of Scientific and Technical Information of China (English)

    何湘柱; 夏畅斌; 王红军; 龚竹清; 蒋汉瀛

    2001-01-01

    A novel process of electroplating amorphous Fe-Cr-Ni alloy in chloride aqueous solution with Fe( Ⅱ ), Ni ( lⅡ ) and Cr( Ⅲ ) was reported. Couple plasma atomic emission spectrometry (ICP-AES), X-ray diffractometry(XRD),scanning electronic microscopy(SEM), microhardness test and rapid heating-cooling method were adopted to detect the properties of the amorphous Fe-Ni-Cr deposit, such as composition, crystalline structure, micrograph, hardness, and adherence between deposit and substrate. The effects of the operating parameters on the electrodeposit of the amorphous FeNi-Cr alloy were discussed in detail. The results show that a 8.7 μm thick mirror-like amorphous Fe-Ni-Cr alloy deposit,with Vicker's hardness of 530 and composition of 45%~55% Fe, 33%~37% Ni, 9%~23% Cr was obtained by electroplating for 20 min at room temperature( 10 30 C ), cathode current 10~16 A/dm2, pH = 1.0~3.0. The XRD pat terns show that there only appears a broad hump around 2θ of 41 °~47 °for the amorphous Fe-Ni-Cr alloy deposit, while the SEM micrographs show that the deposit contains only a few fine cracks but no pinholes.

  18. Reaction of lanthanide elements with Fe–Cr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Inagaki, Kenta, E-mail: inagaki@criepi.denken.or.jp; Ogata, Takanari

    2013-10-15

    During steady-state irradiation of metal fuel in fast reactors, lanthanide fission products react with the Fe-base cladding and cause wastage of the cladding inner surface. In order to provide the basis of the cladding wastage modeling, the authors conducted isothermal annealing tests of diffusion couples consisting of Fe–12wt.%Cr alloy and lanthanide alloy, 13La–24Ce–12Pr–39Nd–12Sm (in wt.%), which simulates fission yield of lanthanide elements. In the temperature range of 773–923 K, Fe diffused into the lanthanide alloy side and formed Fe{sub 2}RE precipitates, where RE stands for lanthanide element mixture. Cr did not migrate evidently. The lanthanide elements diffused into the Fe–Cr side and formed the distinct reaction zone. This reaction zone showed two-phase structure of (Fe,Cr){sub 17}RE{sub 2} and (Fe,Cr){sub 3}RE. Ce and Sm were concentrated in the Fe{sub 2}RE and (Fe,Cr){sub 17}RE{sub 2} phases. The thickness of reaction zone in the Fe–Cr side grew in proportion to the square root of annealing time. The activation energy of the reaction zone growth was determined, which can be the basis of the cladding wastage modeling.

  19. Thermodynamic properties of LaCrO3

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhanheng; XING Xianran; YUAN Wenxia; HUANG Xiaowei; LI Hongwei

    2006-01-01

    The nano powders of LaCrO3 were prepared by a sol-gel route. The heat capacity of LaCrO3 nano powders from 350 to 550 K was measured by DSC method and expressed as: Cp(LaCro3) (±0.112) = 166.844 - 8.500 × 10-3T - 1.022 ×vanic cell. From measured EMF data of the reversible cell, (-) Pt, La2O3, LaF3, O2 (1 atm)|CaF2|O2(1 atm), LaF3, LaCrO3, Cr2O3, Pt(+), and the relevant value of Gibbs free energy, the Gibbs free energy of formation of LaCrO3 was calculated from 700 to 885 K: △G(φ) f,LaCro3 = -1555.364 + 0.354T (kJ/mol) (700-885 K). And the Gibbs free energy change of reaction from simple oxides La2O3 and Cr2O3 was calculated to be: △G(φ) f,ox(LaCrO3) = -94.758 + 8.530 × 10-2T (kJ/mol) (700-885 K).

  20. Analysis of CR1 Repeats in the Zebra Finch Genome

    Directory of Open Access Journals (Sweden)

    George E. Liu

    2013-06-01

    Full Text Available Most bird species have smaller genomes and fewer repeats than mammals. Chicken Repeat 1 (CR1 repeat is one of the most abundant families of repeats, ranging from ~133,000 to ~187,000 copies accounting for ~50 to ~80% of the interspersed repeats in the zebra finch and chicken genomes, respectively. CR1 repeats are believed to have arisen from the retrotransposition of a small number of master elements, which gave rise to multiple CR1 subfamilies in the chicken. In this study, we performed a global assessment of the divergence distributions, phylogenies, and consensus sequences of CR1 repeats in the zebra finch genome. We identified and validated 34 CR1 subfamilies and further analyzed the correlation between these subfamilies. We also discovered 4 novel lineage-specific CR1 subfamilies in the zebra finch when compared to the chicken genome. We built various evolutionary trees of these subfamilies and concluded that CR1 repeats may play an important role in reshaping the structure of bird genomes.

  1. Crítica do direito e teoria dos sistemas

    Directory of Open Access Journals (Sweden)

    Kolja Möller

    2015-12-01

    Full Text Available RESUMO O artigo centra-se em abordagens da teoria crítica do sistema em relação ao direito e à sociedade; mostra como elas modificam a estrutura da teoria ortodoxa dos sistemas e discute a forma de crítica resultante. O argumento principal é de que a guinada luhmanniana à esquerda baseia-se em uma forma aporética da crítica que já foi predominante na crítica do direito da primeira geração da Escola de Frankfurt, notavelmente na obra de Franz L. Neumann, qual seja: a crítica à autorreferência do direito em nome da sociedade e - vice-versa - a crítica à sociedade moderna em nome de um sistema jurídico autônomo. Embora argumentem que esse modo de crítica é altamente produtivo, essas abordagens apresentam uma lacuna quando se trata dos antagonismos sociais e das relações de poder. Uma analogia com o raciocínio de Theodor W. Adorno sobre a relação entre forma e violência é introduzida a fim de contornar as falácias de uma guinada ou niilista ou afirmativa no direito e na sociedade.

  2. Electronic structure and band alignments of ZnTe/CrTe(0 0 1), CdSe/CrTe(0 0 1) and CdTe/CrTe(0 0 1) interfaces

    Indian Academy of Sciences (India)

    F Ahmadian; R Zare

    2011-08-01

    All-electron full potential calculations based on spin density functional theory were performed to study cubic zincblende (ZB) and hexagonal NiAs structures of bulk CrTe and ZnTe/CrTe(0 0 1), CdTe/CrTe(0 0 1) and CdSe/CrTe(0 0 1) interfaces. The lattice mismatch effect in ZB CrTe and magnetic properties of CrTe in the ideal ZB CrTe structure were investigated. The band alignment properties of the ZnTe/CrTe(0 0 1), CdTe/CrTe(0 0 1) and CdSe/CrTe(0 0 1) interfaces were computed and a rather large minority valence band offset of about 1.09 eV was observed in ZnTe/CrTe(0 0 1) heterojunction. Also in the CdTe/CrTe(0 0 1) and CdSe/CrTe(0 0 1) interfaces, the conduction band minimum of minority spin in CrTe was above the conduction band minimum of CdTe and CdSe and so the majority spin electrons could be directly injected to both semiconductors, indicating the possibility of highly efficient spin injection into the CdSe and CdTe semiconductors.

  3. crônicos: mapeamento cruzado

    Directory of Open Access Journals (Sweden)

    Talita do Nascimento da Silva

    2014-01-01

    Full Text Available El objetivo fue analizar las intervenciones de Enfermería en registros médicos de ancianos en atención en programa de gestión de pacientes crónicos, comparándolas con la Clasificación de las Intervenciones de Enfermería. Investigación llevada a cabo en servicio de salud privado del Rio de Janeiro, Brasil, en marzo del 2014. Estudio de mapeo cruzado, con enfoque cuantitativo. Muestra compuesta por 80 registros, según los siguientes criterios: asistidos en 2013; media complejidad II; edad mayor de 64 años; recibieron más de cinco visitas domiciliarias; y activos en diciembre del 2013 en baja complejidad I. Intervenciones frecuentemente mapeadas: educación – proceso de la enfermedad (98%; asesoramiento nutricional (98%; control del ambiente (95%; y promoción del ejercicio (94%. La disminución del estado funcional del programa indica que las directrices eran eficaces, pero aún no estandarizadas. Se recomienda adopción de lenguaje estandarizado.

  4. Isochronicity Correction in the CR Storage Ring

    CERN Document Server

    Litvinov, S; Weick, H; Dolinskii, A

    2013-01-01

    A challenge for nuclear physics is to measure masses of exotic nuclei up to the limits of nuclear existence which are characterized by low production cross sections and short half-lives. The large acceptance Collector Ring (CR) at FAIR tuned in the isochronous ion-optical mode offers unique possibilities for measuring short-lived and very exotic nuclides. However, in a ring designed for maximal acceptance, many factors limit the resolution. One point is a limit in time resolution inversely proportional to the transverse emittance. But most of the time aberrations can be corrected and others become small for large number of turns. We show the relations of the time correction to the corresponding transverse focusing and that the main correction for large emittance corresponds directly to the chromaticity correction for transverse focusing of the beam. With the help of Monte-Carlo simulations for the full acceptance we demonstrate how to correct the revolution times so that in principle resolutions of dm/m=1E-6 ...

  5. Textes de création

    Directory of Open Access Journals (Sweden)

    Auteurs multiples

    2014-04-01

    Full Text Available Du dedans et du dehors… cette expression inscrite dans l’actualité (événements, manifestations, symposiums se réfère aux initiatives culturelles menées en prison et aux productions carcérales diffusées en société. Ce rapport itératif est d’autant plus marqué par une altérité : changement des perceptions, redéfinition des personnes impliquées, transmission de connaissances, etc. Sylvie Frigon ainsi que Tina Charlebois, Éric Charlebois, Guy Thibodeau, Lise Careau, Alberte Villeneuve-Sinclair, Michèle Vinet et Martine Bisson Rodriguez, membres de l’AAOF, animés par une démarche pédagogique de leur crû, pénètrent ces lieux dès l’automne 2011 et donnent une voix aux participants enfermés. Bien sûr, il y a la détention physique à proprement parler, mais aussi l’enfermement-stigmate, l’enfermement-émotion ou l’enfermement-supervision.

  6. Magnetic dipole excitations of 50Cr

    Science.gov (United States)

    Pai, H.; Beck, T.; Beller, J.; Beyer, R.; Bhike, M.; Derya, V.; Gayer, U.; Isaak, J.; Krishichayan, Kvasil, J.; Löher, B.; Nesterenko, V. O.; Pietralla, N.; Martínez-Pinedo, G.; Mertes, L.; Ponomarev, V. Yu.; Reinhard, P.-G.; Repko, A.; Ries, P. C.; Romig, C.; Savran, D.; Schwengner, R.; Tornow, W.; Werner, V.; Wilhelmy, J.; Zilges, A.; Zweidinger, M.

    2016-01-01

    The low-lying M 1 strength of the open-shell nucleus 50Cr has been studied with the method of nuclear resonance fluorescence up to 9.7 MeV using bremsstrahlung at the superconducting Darmstadt linear electron accelerator S-DALINAC and Compton backscattered photons at the High Intensity γ -ray Source (HI γ S ) facility between 6 and 9.7 MeV of the initial photon energy. Fifteen 1+ states have been observed between 3.6 and 9.7 MeV. Following our analysis the lowest 1+ state at 3.6 MeV can be considered as an isovector orbital mode with some spin admixture. The obtained results generally match the estimations and trends typical for the scissors-like mode. Detailed calculations within the Skyrme quasiparticle random-phase-approximation method and the large-scale shell model justify our conclusions. The calculated distributions of the orbital current for the lowest 1+-state suggest the schematic view of Lipparini and Stringari (isovector rotation-like oscillations inside the rigid surface) rather than the scissors-like picture of Lo Iudice and Palumbo. The spin M 1 resonance is shown to be mainly generated by spin-flip transitions between the orbitals of the f p shell.

  7. Crítica de Libros.

    Directory of Open Access Journals (Sweden)

    C Parrado Prieto

    1998-01-01

    Full Text Available Klaus CONRAD, La esquizofrenia incipiente, Ensayo de un análisis gestáltico del delirio, Madrid, Fundación Archivos de Neurobiología, 1997. C. Parrado Prieto, J. A. Arenas García P. POBLACIÓN KNAPPE, Teoría y Práctica del Juego en Psicoterapia, Madrid, Fundamentos, 1997.José Antonio Espina Barrio Bonifacio SANDÍN, Ansiedad, miedos y fobias en niños y adolescentes, Madrid, Dykinson, 1997. Begoña Olabarría Víctor APARICIO (compilador, Orígenes y Fundamentos de la Psiquiatría en España, Madrid, ELA, 1977. Ramón Esteban Arnáiz Aaron GUREVICH, Los orígenes del individualismo europeo, Barcelona, Crítica, 1997. Ramón Esteban Arnáiz MENTALIDAD, CIENCIA E HISTORIA: A PROPÓSITO DE GEOFFREY E. R. LLOYD. Mauricio Jalón

  8. obstructiva crónica (EPOC

    Directory of Open Access Journals (Sweden)

    Stefano Vinaccia

    2006-01-01

    Full Text Available Este artículo presenta los resultados de un estudio desarrollado en Colombia sobre la evaluación de la calidad de vida y sus relaciones con la ansiedaddepresión y el apoyo social en pacientes con diagnóstico de enfermedad pulmonar obstructiva crónica (epoc. Se evaluaron 60 personas con diagnóstico de epoc de diferentes ipss (Instituciones Prestadoras de Servicios de Salud de la ciudad de Medellín, Colombia. Para evaluar la calidad de vida se utilizó el Cuestionario SF36; la ansiedad-depresión fue evaluada mediante el Cuestionario HAD, y se usó el Cuestionario AS para medir apoyo social. No se evidenciaron niveles clínicamente significativos de ansiedad-depresión, la calidad de vida de las funciones físicas fueron las más afectadas especialmente el rol físico (trabajo, estudio en el cuestionario sf36 y en relación al apoyo social se observaron niveles muy altos. En general, hubo alta confiabilidad en todo el estudio.

  9. Magnetic dipole excitations of $^{50}$Cr

    CERN Document Server

    Pai, H; Beller, J; Beyer, R; Bhike, M; Derya, V; Gayer, U; Isaak, J; Kvasil, J; Loher, B; Nesterenko, V O; Pietralla, N; Martinez-Pinedo, G; Mertes, L; Ponomarev, V Yu; Reinhard, P -G; Repko, A; Ries, P C; Romig, C; Savran, D; Schwengner, R; Tornow, W; Werner, V; Wilhelmy, J; Zilges, A; Zweidinger, M

    2016-01-01

    The low-lying $M1$-strength of the open-shell nucleus $^{50}$Cr has been studied with the method of nuclear resonance fluorescence up to 9.7 MeV, using bremsstrahlung at the superconducting Darmstadt linear electron accelerator S-DALINAC and Compton backscattered photons at the High Intensity $\\gamma$-ray Source (HI$\\gamma$S) facility between 6 and 9.7 MeV of the initial photon energy. Fifteen $1^{+}$ states have been observed between 3.6 and 9.7 MeV. Following our analysis, the lowest $1^{+}$ state at 3.6 MeV can be considered as an isovector orbital mode with some spin admixture. The obtained results generally match the estimations and trends typical for the scissors-like mode. Detailed calculations within the Skyrme Quasiparticle Random-Phase-Approximation method and the Large-Scale Shell Model justify our conclusions. The calculated distributions of the orbital current for the lowest $1^{+}$-state suggest the schematic view of Lipparini and Stringari (isovector rotation-like oscillations inside the rigid ...

  10. Ten years of CR physics with PAMELA

    Science.gov (United States)

    Galper, A.; Spillantini, P.

    2017-09-01

    The satellite borne Pamela instrument is dedicated to the precise and high statistics study of CR fluxes on a four decades energy range. Pamela experiment is the last step of the "Russian-Italian Mission" (RIM) program established in 1992 between several Italian and Russian institutes and with the participation of Sweden and Germany. Designed as a cosmic ray observatory at 1 AU, it extensive program is made possible thanks to the outstanding performance of the instrument, the low energy threshold, the quasi-polar orbit and the 10 years duration of the observation. The physics program pays particular attention to the study of particles and antiparticles fluxes and includes search for dark matter, primordial antimatter, new matter in the Universe, study of cosmic-ray propagation, solar physics and solar modulation, and terrestrial magnetosphere. Very important is the discovery of the anomalous increase of the positron flux at energies higher that 50 GeV (the so called "Pamela anomaly"), and the abrupt spectral hardening of H and He, challenging the current paradigm of cosmic-ray acceleration and propagation in the Galaxy.

  11. Cr{sub 2}Nb-based alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A. [Oak Ridge National Lab., TN (United States)] [and others

    1995-06-01

    The objective of this task is to develop a new generation of structural materials based on intermetallic alloys for use as critical hot components in advanced fossil energy conversion systems. The intermetallic phase, Cr{sub 2}Nb, with a complex cubic structure (C-15) has been selected for this development because of its high melting point (1770{degrees}C), relatively low material density (7.7 g/cm{sup 2}), excellent high-temperature strength (at 1000 to 1250{degrees}C), and potential resistance to oxidation and corrosion. This intermetallic phase, like many other Laves phases, has a wide range of compositional homogeneity suggesting the possibility of improving its mechanical and metallurgical properties by alloying additions. The major engineering concern with Cr{sub 2}Nb and other A{sub 2}B Laves phases is their poor fracture toughness and fracture resistance at ambient temperatures. The single-phase Cr{sub 2}Nb is very hard ({approximately}800 DPH) and brittle at room temperature. Because of this brittleness, the development effort has concentrated on two-phase structures containing the hard intermetallic phase Cr{sub 2}Nb and the softer Cr-rich solid solution phase. Potential applications of Cr-Cr{sub 2}Nb alloys include hot components (for example, air heat exchangers and turbine blades) in advanced energy conversion systems and heat engines, wear-resistant parts in coal handling systems (e.g., nozzles), drill bits for oil/gas wells, and valve guides in diesel engines. Current studies are focuses on enhancement of fracture resistance in tension at ambient temperatures and oxidation resistance above 1000{degrees}C. This report summarizes recent progress on controlling microstructure and improving the mechanical and metallurgical properties and the high-temperature corrosion behavior of Cr-Cr{sub 2}Nb alloys through alloying conditions, material processing, and heat treatment.

  12. [Preparation of electrodeposited Cr-La coating and its spectral properties].

    Science.gov (United States)

    Liu, Xiao-zhen; Wang, Gang; Song, Ling-ling; Li, Xin; Zhu, Xu-qiang

    2011-07-01

    Cr-La coating (dc) and Cr-La coating (pulse) were prepared by electrodeposition method of direct current and pulsating current respectively. The Cr-La coating (dc) and Cr-La coating (pulse) were characterized with ICP-AES, EDAX, XRD and SEM techniques, respectively. Cr-La coating(dc) was amorphous. There were crystalline La and CrC in Cr-La coating (pulse). The microhardness of the Cr-La coating(dc) and Cr-La coating (pulse) were as high as 860.3 and 930.2 HV respectively, which were higher 11.15% and 20.18% higher than that of the Cr coating (774.0 HV). The wear weight losses of Cr-La coating(dc) and Cr-La coating(pulse) were 1.29 and 2.25 times lower than that of Cr coating, respectively. The friction coefficient of Cr coating, Cr-La coating(dc) and Cr-La coating(pulse) were 0. 884, 0. 640 and 0. 648 respectively. The properties of wear weight loss and microhardness of coatings were improved with pulsating current. The wear weight loss and microhardness of Cr-La coating(pulse) were lower 1.75 time lower and higher 8.13% higher than that of the Cr-La coating(dc), respectively.

  13. Ferromagnetism in Cr-doped passivated AlN nanowires

    KAUST Repository

    Kanoun, Mohammed

    2014-01-01

    We apply first principles calculations to predict the effect of Cr doping on the electronic and magnetic properties of passivated AlN nanowires. We compare the energetics of the possible dopant sites and demonstrate the favorable configuration ferromagnetic ordering. The charge density of the pristine passivated AlN nanowires is used to elucidate the bonding character. Spin density maps demonstrate an induced spin polarization for N atoms next to dopant atoms, though most of the magnetism is carried by the Cr atoms. Cr-doped AlN nanowires turn out to be interesting for spintronic devices. © 2014 the Partner Organisations.

  14. On the vanishing rate of smooth CR functions

    Directory of Open Access Journals (Sweden)

    Giuseppe Della Sala

    2014-01-01

    Full Text Available Let be a lineally convex hypersurface of ℂⁿ of finite type, 0∈. Then there exist non-trivial smooth CR functions on that are flat at 0, i.e. whose Taylor expansion about 0 vanishes identically. Our aim is to characterize the rate at which flat CR functions can decrease without vanishing identically. As it turns out, non-trivial CR functions cannot decay arbitrarily fast, and a possible way of expressing the critical rate is by comparison with a suitable exponential of the modulus of a local peak function.

  15. Improving osseointegration of Co-Cr by nanostructured titanium coatings.

    Science.gov (United States)

    Pham, Vuong-Hung

    2014-01-01

    This study reports the deposition of nanostructured Ti films on Co-Cr substrates to improve their surface characteristics and biocompatibility. The microstructure of the Ti films was controlled by application of negative substrate bias voltages. The surface roughness of Co-Cr implants was increased significantly after Ti coatings. The nanostructured Ti films are found to improve osteointergration of Co-Cr implants as indicated by enhancing cellular attachment, proliferation and differentiation, which was attributed mainly to the application of a biocompatible Ti coating, possessed a higher surface area for cell attachments and growth.

  16. Planed defects in (Cr,Fe)7C3

    Institute of Scientific and Technical Information of China (English)

    李玉清

    1996-01-01

    The characteristics of planed defects in (Cr,Fe)7C3 in a chromium steel and two kinds of cast alloys have been delineated.Combining matrix analysis of electron diffraction pattern with calculated angle between planed detect traces and using compound reciprocal space composed of matrix cell and two rotative cells,the [011] and [013] planed defects in (Cr,Fe)-C3 have been determined in an all-round way.A crystallographic model for (Cr.Fe)2C3 has been proposed.

  17. Electrochemical Behavior and Hydrophobic Properties of CrN and CrNiN Coatings in Simulated Proton Exchange Membrane Fuel Cell Environment

    Directory of Open Access Journals (Sweden)

    JIN Jie

    2016-10-01

    Full Text Available The CrN and CrNiN coatings were prepared on the surface of 304 stainless steel by closed field unbalanced magnetron sputtering.X ray diffraction and field emission scanning electron microscopy were used to characterize the structure and morphology of the coatings.The electrochemical corrosion properties under the simulated proton exchange membrane fuel cell(PEMFC environment, interfacial contact resistance and hydrophobic properties of the two kinds of different coatings were investigated by electrochemical methods,contact resistance test and hydrophobic test,respectively.The results indicate that CrN coating mainly consists of CrN and Cr2N phase,CrN and Cr2N phases in the CrNiN coating are less compared to CrN film, and Ni exist as element in CrNiN coating; dynamic polarization tests show the coating is of better corrosion resistance,whereas the corrosion resistance of CrNiN coating is worse than that of CrN coating,constant potential polarization test shows the corrosion current density of CrN and CrNiN coatings are equivalent; CrN and CrNiN coatings significantly reduce the interfacial contact resistance of the 304 stainless steel,among which CrN coating has the smallest contact resistance; and CrNiN coating which has better hydrophobicity than that of CrN coating is more beneficial for the water management in proton exchange membrane fuel cell.

  18. Isothermal superplastic solid state bonding of 40Cr and Cr12MoV steels based on surface modification

    Institute of Scientific and Technical Information of China (English)

    Zhang Keke; Zhang Zhanling; Liu Shuai; Yue Yun; Ma Ning; Yang Yunlin

    2009-01-01

    Based on the feasibility of isothermal superplastic solid state bonding of 40Cr and Cr12MoV steels, the surfaces of both steels to be bonded were ultra-fined through high frequency hardening, then the superplastic solid state bonding were conducted, the microstructure and fracture surface of bonded joint were observed and analysed, and bonding mechanisms was researched. The experimental results show that with the sample surfaces of 40Cr and Cr12MoV steels after the high frequency hardening, under the prepressing stress of 56.6 MPa, initial strain rate of 1.5×10~(-2) min~(-1) and at the bonding temperature of 800-820℃, the superplastic solid state bonding can be carried out in about 3.5min, and the joint strength is up to that of 40Cr steel base metal and the radial expansion ratio of the joint does not exceed 6%. The superplastic solid state bonding parameter of both steels is within the ranges of the isothermal compressive superplastic deformation of Cr12MoV steel, and the deformation in Cr12MoV steel side near the interfacial zone of joint presents the characteristic of superplasticity. In bonding process, the atoms in two sides of joint interface have diffused each other.

  19. Effects of Cr and Ni on Interdiffusion and Reaction between U and Fe-Cr-Ni Alloys

    Energy Technology Data Exchange (ETDEWEB)

    K. Huang; Y. Park; L. Zhou; K.R. Coffey; Y.H. Sohn; B.H. Sencer; J. R. Kennedy

    2014-08-01

    Metallic U-alloy fuel cladded in steel has been examined for high temperature fast reactor technology wherein the fuel cladding chemical interaction is a challenge that requires a fundamental and quantitative understanding. In order to study the fundamental diffusional interactions between U with Fe and the alloying effect of Cr and Ni, solid-to-solid diffusion couples were assembled between pure U and Fe, Fe–15 wt.%Cr or Fe–15 wt.%Cr–15 wt.%Ni alloy, and annealed at high temperature ranging from 580 to 700 °C. The microstructures and concentration profiles that developed from the diffusion anneal were examined by scanning electron microscopy, and X-ray energy dispersive spectroscopy (XEDS), respectively. Thick U6Fe and thin UFe2 phases were observed to develop with solubilities: up to 2.5 at.% Ni in U6(Fe,Ni), up to 20 at.%Cr in U(Fe, Cr)2, and up to 7 at.%Cr and 14 at.% Ni in U(Fe, Cr, Ni)2. The interdiffusion and reactions in the U vs. Fe and U vs. Fe–Cr–Ni exhibited a similar temperature dependence, while the U vs. Fe–Cr diffusion couples, without the presence of Ni, yielded greater activation energy for the growth of intermetallic phases – lower growth rate at lower temperature but higher growth rate at higher temperature.

  20. Mixing of Cr and Si atoms induced by noble gas ions irradiation of Cr/Si bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Tobbeche, S., E-mail: said_tobbeche@yahoo.com [Faculte des Sciences, Universite El-Hadj Lakhdar, Batna 05000 (Algeria); Boukhari, A. [Faculte des Sciences, Universite El-Hadj Lakhdar, Batna 05000 (Algeria); Khalfaoui, R. [Faculte des Sciences, Universite M. Bougara, Boumerdes 35000 (Algeria); Amokrane, A. [Faculte de Physique, USTHB, B.P. 32 El-Alia, Bab-Ezzouar 16111 (Algeria); Ecole Nationale Preparatoire aux Etudes d' Ingeniorat, Route Nationale, Rouiba (Algeria); Benazzouz, C.; Guittoum, A. [Centre de Recherche Nucleaire d' Alger, 02, Boulevard Frantz Fanon, B.P. 399 Alger-Gare (Algeria)

    2011-12-15

    Cr/Si bilayers were irradiated at room temperature with 120 keV Ar, 140 keV Kr and 350 keV Xe ions to fluences ranging from 10{sup 15} to 2 Multiplication-Sign 10{sup 16} ions/cm{sup 2}. The thickness of Cr layer evaporated on Si substrate was about 400 A. Rutherford backscattering spectrometry (RBS) was used to investigate the atomic mixing induced at the Cr-Si interface as function of the incident ion mass and fluence. We observed that for the samples irradiated with Ar ions, RBS yields from both Cr layer and Si substrate are the same as before the irradiation. There is no mixing of Cr and Si atoms, even at the fluence of 2 Multiplication-Sign 10{sup 16} ions/cm{sup 2}. For the samples irradiated with Kr ions, a slight broadening of the Cr and Si interfacial edges was produced from the fluence of 5 Multiplication-Sign 10{sup 15} ions/cm{sup 2}. The broadening of the Cr and Si interfacial edges is more pronounced with Xe ions particularly to the fluence of 10{sup 16} ions/cm{sup 2}. The interface broadening was found to depend linearly on the ion fluence and suggests that the mixing is like a diffusion controlled process. The experimental mixing rates were determined and compared with values predicted by ballistic and thermal spike models. Our experimental data were well reproduced by the thermal spikes model.

  1. Spectroscopic properties of {Cr}^{3+} in the spinel solid solution {ZnAl}_{2-x}{Cr}x{O}_4

    Science.gov (United States)

    Verger, Louisiane; Dargaud, Olivier; Rousse, Gwenaelle; Rozsályi, Emese; Juhin, Amélie; Cabaret, Delphine; Cotte, Marine; Glatzel, Pieter; Cormier, Laurent

    2016-01-01

    The evolution of the structural environment of {Cr}{^{3+}} along the solid solution {ZnAl}_{2-x}{Cr}x{O}_4 has been investigated using a multi-analytical approach. X-ray diffraction confirms that the system follows Vegard's law. Diffuse reflectance spectra show a decrease of the crystal field parameter with the Cr content, usually related to the increase of the Cr-O bond length in a point charge model. This interpretation is discussed and compared to the data obtained by first-principle calculations based on density functional theory. X-ray absorption near edge structure spectra at the Cr K-edge show a pronounced evolution in the pre-edge with the Cr content, characterised by the appearance of a third feature. Calculations enable to assign the origin of this feature to Cr neighbours. The colour change from pink to brownish pink and eventually green along the solid solution has also been quantified by calculating the L*, a*, b* and x, y coefficients in the system defined by the International Commission on Illumination.

  2. Speciation of Cr(III) and Cr(VI) after column solid phase extraction on Amberlite XAD-2010.

    Science.gov (United States)

    Bulut, V N; Duran, C; Tufekci, M; Elci, L; Soylak, M

    2007-05-08

    A speciation procedure for Cr(III) and Cr(VI) based on column solid phase extraction on Amberlite XAD-2010 and flame atomic absorption spectrometry combination. Cr(VI) was quantitatively recovered on Amberlite XAD-2010 resin at pH range of 2.0-3.0 as its diethyldithiocarbamate complex, while the recoveries of Cr(III) was below 5%. The influences of the various parameters including amounts of the reagents, eluent type and its volume, sample volume, etc., on the quantitative recoveries were examined. The interference of matrix and coexistent elements for method were studied. The detection limit (corresponding to three times the standard deviation of the blank) and the enrichment factor for Cr(VI) were found to be 1.28 microg/L and 25, respectively. To verify the accuracy of the method, drinking water certified reference material (CRM-TMDW-500) was analyzed and the results obtained were in good agreement with the certified value. The proposed method has been successfully applied to the speciation of Cr(III) and Cr(VI) in water samples and preconcentration of total chromium in environmental samples.

  3. Characteristics of Eutectic α(Cr,Fe)-(Cr,Fe)23C6 in the Eutectic Fe-Cr-C Hardfacing Alloy

    Science.gov (United States)

    Lai, Hsuan-Han; Hsieh, Chih-Chun; Lin, Chi-Ming; Wu, Weite

    2016-10-01

    A specific eutectic (Cr,Fe)-(Cr,Fe)23C6 structure had been previously reported in the research studies of Fe-Cr-C hardfacing alloys. In this study, a close observation and discussion of the eutectic (Cr,Fe)-(Cr,Fe)23C6 were conducted. The eutectic solidification occurred when the chromium content of the alloy exceeded 35 wt pct. The eutectic structure showed a triaxial radial fishbone structure which was the so called "complex regular structure." Lamellar costa plates showed local asymmetry at two sides of a spine. Individual costae were able to combine as one, and spines showed extra branches. Costae that were nearly parallel to the heat flow direction were longer than those that were vertical to the heat flow direction. The triaxial spines preferred to intersect at 120 deg, while the costae preferred to intersect the spine at 90 deg and 35.26 deg due to the lattice relationships. The solidified metal near the fusion boundary showed an irregular structure instead of a complex regular structure. The reason for the irregular morphology was the high growth rate near the fusion boundary.

  4. Structural, electrical, and dielectric properties of Cr doped ZnO thin films: Role of Cr concentration

    Science.gov (United States)

    Gürbüz, Osman; Okutan, Mustafa

    2016-11-01

    An undoped zinc oxide (ZnO) and different concentrations of chromium (Cr) doped ZnO CrxZnO1-x (x = 3.74, 5.67, 8.10, 11.88, and 15.96) thin films were prepared using a magnetron sputtering technique at room temperature. These films were characterized by X-ray diffraction (XRD), High resolution scanning electron microscope (HR-SEM), and Energy dispersive X-ray spectrometry (EDS). XRD patterns of all the films showed that the films possess crystalline structure with preferred orientation along the (100) crystal plane. The average crystallite size obtained was found to be between 95 and 83 nm which was beneficial in high intensity recording peak. Both crystal quality and crystallite sizes decrease with increasing Cr concentration. The crystal and grain sizes of the all film were investigated using SEM analysis. The surface morphology that is grain size changes with increase Cr concentration and small grains coalesce together to form larger grains for the Cr11.88ZnO and Cr15.96ZnO samples. Impedance spectroscopy studies were carried out in the frequencies ranging from 5 Hz to 13 MHz at room temperature. The undoped ZnO film had the highest dielectric value, while dielectric values of other films decreased as doping concentrations increased. Besides, the dielectric constants decreased whereas the loss tangents increased with increasing Cr content. This was considered to be related to the reduction of grain size as Cr content in ZnO host material increased. Furthermore, by increasing the Cr concentration, the improved electrical performance was observed. The electrical resistivity of samples decreased from 3.98 × 10-2 Ω cm to 4.03 × 10-4 Ω cm with the increase in Cr content. For these reasons, Cr doped ZnO (Cr:ZnO) thin films may be used in microwave devices as the electrical conductivity increases while dielectric constant decreases with the Cr content.

  5. Properties of Cr3C2-NiCr Cermet Coating Sprayed by High Power Plasma and HVOF Processes

    OpenAIRE

    Otsubo, Fumitaka; Era, Hidenori; Kishitake, K; Uchida, T.

    2000-01-01

    The structure, hardness and shear adhesion strength have beeninvestigated in Cr3C2-NiCr cermet coatings sprayed onto a mild steelsubstrate by 200 kW high power plasma spraying (HPS) and high velocityoxy-fuel (HVOF) processes. Amorphous and supersaturated nickel phasesform in both as-sprayed coatings. The hardness of the HVOF coating ishigher than that of the HPS coating because the HVOF coating containsmore non-melted Cr3C2 carbide particles. On heat-treating at 873 K, theamorphous phase deco...

  6. The Aqueous Alteration of CR Chondrites: Experiments and Geochemical Modeling

    Science.gov (United States)

    Perronnet, M.; Berger, G.; Zolensky, M. E.; Toplis, M. J.; Kolb, V. M.; Bajagic, M.

    2007-03-01

    Laboratory alteration experiments were performed on mineralogical assemblages having the unaltered CR composition. The mineralogy of reaction products was compared to that of Renazzo and GRO 95577 and to predictions of geochemical modeling.

  7. Magnetization and neutron diffraction studies on FeCrP

    Indian Academy of Sciences (India)

    Sudhish Kumar; Anjali Krishnamurthy; Bipin K Srivastava; A Das; S K Paranjpe

    2004-08-01

    Crystal structure and magnetic behaviour of FeCrP have been investigated using magnetization and neutron diffraction measurements. FeCrP crystallizes in orthorhombic FeZrP type structure (nma space group, = 4) in which Cr atoms occupy the pyramidal site and Fe atoms occupy the tetrahedral site with total preference. Structural parameters including positional parameters have been refined. The refined values of positional parameters for Fe and Cr are quite different from those in FeZrP. The nature of magnetization{temperature curve is suggestive of antiferromagnetic nature with N = 280 (± 10) K. Preliminary analysis of neutron diffraction pattern at 13 K is indicative of a rather complicated magnetic structure.

  8. Analysis of precipitation in a Cu-Cr-Zr alloy

    Institute of Scientific and Technical Information of China (English)

    Zhao Mei; Lin Guobiao; Wang Zidong; Zhang Maokui

    2008-01-01

    Precipites in Cu-0.42%Cr-0.21%Zr alloy were analyzed by using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDXS) and transmission electron microscope (TEM). After the solid solution was performed at 980℃ for 2 h, water-quenched and aged at 450℃ for 20 h, the precipite had a bimodal distribution of precipitate size. The coarse precipitates are pure Cr and Cu5Zr, the dispersed fine precipitate is CrCu2(Zr, Mg) and pure Cr ranging from 1 to 50 nm. The coarse phases formed during solidification and were left undissolved during solid solution. The fine precipitates are the hardening precipitates that form due to decomposition of the supersaturated solid solution during aging.

  9. Theory of room temperature ferromagnetism in Cr modified DNA nanowire

    Science.gov (United States)

    Paruğ Duru, Izzet; Değer, Caner; Eldem, Vahap; Kalayci, Taner; Aktaş, Şahin

    2016-04-01

    We investigated the magnetic properties of Cr3+ (J  Monte Carlo simulation method-based Metropolis algorithm is used to figure out the thermodynamic quantities of nanowire formed by Cr M-DNA followed by analysing the dependency of the ferromagnetic behaviour of the M-DNA to dopant concentration. It is understood that ion density/base and ion density/helical of Cr3+ ions can be a tuning parameter, herewith the dopant ratio has an actual importance on the magnetic characterization of M-DNA nanowire (3%-20%). We propose the source of magnetism as an exchange interaction between Cr and DNA helical atoms indicated in the Heisenberg Hamiltonian.

  10. Analysis of precipitation in a Cu-Cr-Zr alloy

    Directory of Open Access Journals (Sweden)

    Wang Zidong

    2008-11-01

    Full Text Available Precipites in Cu-0.42%Cr-0.21%Zr alloy were analyzed by using scanning electron microscope (SEM, energy dispersive X-ray spectroscopy (EDXS and transmission electron microscope (TEM. After the solid solution was performed at 980 ℃ for 2 h, water-quenched and aged at 450 ℃ for 20 h, the precipite had a bimodal distribution of precipitate size. The coarse precipitates are pure Cr and Cu5Zr, the dispersed fine precipitate is CrCu2(Zr,Mg and pure Cr ranging from 1 to 50 nm. The coarse phases formed during solidifi cation and were left undissolved during solid solution. The fi ne precipitates are the hardening precipitates that form due to decomposition of the supersaturated solid solution during aging.

  11. Structure and corrosion properties of PVD Cr-N coatings

    CERN Document Server

    Liu, C; Ziegele, H; Leyland, A; Matthews, A

    2002-01-01

    PVD Cr-N coatings produced by physical vapor deposition (PVD) are increasingly used for mechanical and tribological applications in various industrial sectors. These coatings are particularly attractive for their excellent corrosion resistance, which further enhances the lifetime and service quality of coated components. PVD Cr-N coated steels in an aqueous solution are usually corroded by galvanic attack via through-coating 'permeable' defects (e.g., pores). Therefore, the corrosion performance of Cr-N coated steel is determined by a number of variables of the coating properties and corrosive environment. These variables include: (i) surface continuity and uniformity; (ii) through-coating porosity; (iii) film density and chemical stability; (iv) growth stresses; (v) interfacial and intermediate layers; (vi) coating thickness; (vii) coating composition; and (viii) substrate properties. In this article, PVD Cr-N coatings were prepared, by electron-beam PVD and sputter deposition, with different compositions, t...

  12. Fibrations and globalizations of compact homogeneous CR-manifolds

    Science.gov (United States)

    Gilligan, B.; Huckleberry, Alan T.

    2009-06-01

    Fibration methods which were previously used for complex homogeneous spaces and CR-homogeneous spaces of special types [1]-[4] are developed in a general framework. These include the \\mathfrak{g}-anticanonical fibration in the CR-setting, which reduces certain considerations to the compact projective algebraic case, where a Borel-Remmert type splitting theorem is proved. This leads to a reduction to spaces homogeneous under actions of compact Lie groups. General globalization theorems are proved which enable one to regard a homogeneous CR-manifold as an orbit of a real Lie group in a complex homogeneous space of a complex Lie group. In the special case of CR-codimension at most two, precise classification results are proved and are applied to show that in most cases there exists such a globalization.

  13. Fibrations and globalizations of compact homogeneous CR-manifolds

    Energy Technology Data Exchange (ETDEWEB)

    Gilligan, B [University of Regina, Regina (Canada); Huckleberry, Alan T [Ruhr-Universitaet Bochum, Mathematischer Institut, Bochum (Germany)

    2009-06-30

    Fibration methods which were previously used for complex homogeneous spaces and CR-homogeneous spaces of special types [1]-[4] are developed in a general framework. These include the g-anticanonical fibration in the CR-setting, which reduces certain considerations to the compact projective algebraic case, where a Borel-Remmert type splitting theorem is proved. This leads to a reduction to spaces homogeneous under actions of compact Lie groups. General globalization theorems are proved which enable one to regard a homogeneous CR-manifold as an orbit of a real Lie group in a complex homogeneous space of a complex Lie group. In the special case of CR-codimension at most two, precise classification results are proved and are applied to show that in most cases there exists such a globalization.

  14. Optimization of CR-39 for fast neutron dosimetry applications

    CERN Document Server

    Vilela, E; Giacomelli, G; Giorgini, M; Morelli, B; Patrizii, L; Serra, P; Togo, V

    1999-01-01

    We present the results of an experimental work aimed at improving the performances of the CR-39[reg] (Registered Trademark of PPG Industries Inc.) nuclear track detector for neutron dosimetry applications. The work was done in collaboration with the Intercast Europe S.p.A., producer of CR-39 for commercial and scientific applications. We compare the CR-39 made with different additives concentrations and different polymerization processes. We evaluate the response of the CR-39 to fast neutrons from three sources: sup 2 sup 4 sup 1 Am-Be, sup 2 sup 5 sup 2 Cf and sup 2 sup 3 sup 8 Pu-Li. Particular attention was paid to background fluctuations that limit the lower detectable dose.

  15. BIOSORPTION OF CR (VI BY RESTING CELLS OF ASPERGILLUS SP.

    Directory of Open Access Journals (Sweden)

    M. Sen , M. Ghosh Dastidar

    2007-01-01

    Full Text Available Biosorption of Cr(VI from aqueous solution was studied in a batch bioreactor using the resting cells of filamentous fungal biomass (Aspergillus sp. isolated from industrial wastewaters. The specific Cr(VI removal (mg/g of dried biomass decreased with increase in pH and increased with increase in initial Cr(VI concentration, upto 500 mg/L. By increasing biomass concentration from 2.4 to 5.2 g/L, the specific metal removal remained almost constant. The studies carried out by using the resting cells from various stages of growth indicated maximum Cr(VI removal of 34.8 mg/g using the biomass from the beginning of the stationary phase. The adsorption equilibrium constants Qº (42.9 mg/g and b (0.0091/mg were obtained from the Langmuir adsorption isotherm model.

  16. 9 Cr-- 1 Mo steel material for high temperature application

    Science.gov (United States)

    Jablonski, Paul D; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

    2012-11-27

    One or more embodiments relates to a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The 9 Cr-1 Mo steel has a tempered martensite microstructure and is comprised of both large (0.5-3 .mu.m) primary titanium carbides and small (5-50 nm) secondary titanium carbides in a ratio of. from about 1:1.5 to about 1.5:1. The 9 Cr-1 Mo steel may be fabricated using exemplary austenizing, rapid cooling, and tempering steps without subsequent hot working requirements. The 9 Cr-1 Mo steel exhibits improvements in total mass gain, yield strength, and time-to-rupture over ASTM P91 and ASTM P92 at the temperature and time conditions examined.

  17. The Crystal Structure of SrCrO4

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    1996-01-01

    X-ray diffraction diagrams taken with Cu-K(alpha) radiation in a Bragg-Brentano diffractometer have shown that the La0.8Sr0.2CrO3 powders, synthesized by drip/spray pyrolysis in a rotating tube furnace at 600-700 oC, contained SrCrO4, in addition to the ceramic perovskite phase. By means of Rietv......X-ray diffraction diagrams taken with Cu-K(alpha) radiation in a Bragg-Brentano diffractometer have shown that the La0.8Sr0.2CrO3 powders, synthesized by drip/spray pyrolysis in a rotating tube furnace at 600-700 oC, contained SrCrO4, in addition to the ceramic perovskite phase. By means...

  18. Effect of film thickness on magnetic properties of Cr/SmCo/Cr films

    Institute of Scientific and Technical Information of China (English)

    LI Ning; LI Baohe; FENG Chun; LI Minghua; YU Guanghua

    2012-01-01

    Cr/SmCo/Cr films with different SmCo thickness were deposited on glass substrates by magnetron sputtering,followed by an annealing process at 550℃for 20 min.Experimental results showed that the SmCo fihn of 30 nm exhibited two-phase behavior in the demagnetization process,the obvious kink was observed near zero.For the SmCo film of 50 nm,the kink was invisible,and a single phase like behavior was obtained in the demagnetization process.The reversal behavior became consistent in the thicker films.Moreover,the coercivity reduced and the saturated magnetization increased obviously with the increasing thickness.X-ray diffraction results indicated that the average grain size of SmCo5 in the thicker films were almost 30 nm,but the quantity of SmCo5 grains increased with the increasing thickness,which enhanced the intergrain exchange coupling (IEC) of the SmCo5 hard phases.The increase of lEC improved the magnetic properties of SmCo films with increasing thickness.

  19. Creep behavior of oxide dispersion strengthened 8Cr-2WVTa and 8Cr-1W steels

    Energy Technology Data Exchange (ETDEWEB)

    Shinozuka, K. [Department of Material Science and Engineering, National Defense Academy, Yokosuka, Kanagawa 239-8686 (Japan)], E-mail: kshinozu@nda.ac.jp; Tamura, M.; Esaka, H. [Department of Material Science and Engineering, National Defense Academy, Yokosuka, Kanagawa 239-8686 (Japan); Shiba, K.; Nakamura, K. [Japan Atomic Energy Agency, Tokai-mura, Naka-Gun, Ibaraki 319-1195 (Japan)

    2009-01-31

    Microstructures and creep behavior of two martensitic oxide dispersion strengthened (ODS) steels 8%Cr-2%W-0.2%V-0.1%Ta (J1) and 8%Cr-1%W (J2) with finely dispersed Y{sub 2}Ti{sub 2}O{sub 7} have been investigated. Creep tests have been carried out at 670, 700 and 730 deg. C. Creep strength of J1 is stronger than that of any other ODS martensitic steels and the hoop strength of the ferritic ODS steel cladding. At the beginning of creep test, shrinkage was frequently observed for J1. This is one of the reasons for high creep strength of J1. The {delta}-ferrite, which is untransformed to austenite at hot isostatic press and hot rolling temperatures, was elongated along the rolling direction, and volume fraction of {delta}-ferrite in J1 is larger than J2. Although the elongated {delta}-ferrite affects the anisotropy of creep behavior, the extent of anisotropy in J1 is not so large as that of the ferritic ODS steel.

  20. Cr3+ NMR for Multiferroic Chromium spinel ZnCr2Se4

    Science.gov (United States)

    Park, Sejun; Kwon, Sangil; Lee, Soonchil; Khim, Seunghyun; Bhoi, Dilip Kumar; Kim, Kee Hoon

    Multiferroic systems including ZnCr2Se4, the chromium spinel with helical spin structure, have been in huge interest for decades due to its physical variety and applicability. In the temperature range between 21K and 80K, this material shows negative thermal expansion. Due to the bond frustration, the spins of the chromium ions order helically below the transition temperature, 21K, though the exchange constant tends to make a ferro-order. The anomalous 1storder-like magnetic transition is yet clarified and still an interesting topic. To probe microscopic origin of these features, we measured zero-field NMR of Cr3+ ions having nuclear spin 3/2. Six peaks were observed revealing Nuclear Quadrupole Resonance(NQR) and anisotropic hyperfine field at chromium sites. The NQR spectrum reveals that the structure is highly distorted below the magnetic transition temperature where the normal Jahn-Teller distortion is absent. Temperature dependence of the spectrum is also measured to obtain the magnetization as a function of temperature.

  1. Application of termite nest for adsorption of Cr(VI).

    Science.gov (United States)

    Araújo, B R; Reis, J O M; Rezende, E I P; Mangrich, A S; Wisniewski, A; Dick, D P; Romão, L P C

    2013-11-15

    This work proposes the use of tree termite nest as an adsorbent for the reduction/removal of Cr(VI) present in aqueous solution. In laboratory experiments, adsorption of Cr(VI) was sensitive to pH in the range investigated (2-5), with maximum adsorption capacity achieved at pH 2 (3.70 ± 0.04 mg g(-1), representing 93.2% removal of Cr). The termite nest was characterized by off-line pyrolysis GC/MS (py-GC/MS), infrared spectroscopy (FTIR), and electron paramagnetic resonance spectroscopy (EPR). Pyrolysis of the adsorbent produced a complex mixture of aromatic compounds, including the guaiacyl and syringilic derivatives that are characteristic of lignocellulosic materials. Infrared spectroscopy revealed deprotonation of the carboxylic acid group of the biomass with increasing pH, which was associated with a decrease in the capacity for adsorption of Cr(VI). The EPR g-factor for the termite nest samples varied between 2.0037 and 2.0038, indicating the presence of organic free radicals that were responsible for the redox reaction. A second line with g-factor values of 1.9790, only observed for the samples after contact with Cr(VI) solutions at different pH values, was assigned to Cr(III)-Cr(III) exchange coupled pairs, which explained the capacity of the adsorbent to retain a large portion of the Cr(III) ions produced after reduction of Cr(VI) to Cr(III). Fixed-bed column experiments showed that the termite nest had a maximum adsorption capacity of 18.60 mg Cr g(-1), an adsorption efficiency varying between 60.8 and 97.4%, and a desorption efficiency varying between 54.5 and 91.4%, for three successive cycles. The adsorbent presented excellent performance in the removal of chromium under acidic conditions, with the advantage that it could be regenerated and reused. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Adsorption and mobility of Cr(III)-organic acid complexes in soils.

    Science.gov (United States)

    Cao, Xinhua; Guo, Jing; Mao, Jingdong; Lan, Yeqing

    2011-09-15

    The soluble Cr(III) is likely to be complexed with organic ligands in ligand-rich soil. Cr(VI) chemical reduction by organic acids and bioreduction by microorganisms can produce soluble Cr(III)-organic acids complexes. Thus, it is of great significance to investigate the absorption and mobility of Cr(III)-organic acid complexes in soils. In this study, Cr(III)-EDTA and Cr(III)-cit were prepared and purified, and then were examined for adsorption and mobility. The results demonstrated that Cr(III) was strongly bound to soil, while Cr(III)-organic acid complexes had no or slight interaction with soils since Cr(III)-EDTA and Cr(III)-cit complexes mainly existed as the forms of [Cr(III)-EDTA](-) and [Cr(III)-cit], respectively, under the tested conditions with initial pH 4.0-9.0. The adsorption of Cr(III) increased but that of Cr(III)-organic acid complexes decreased with the content of soil organic matter. Compared with Cr(III)-EDTA, the mobility of Cr(III)-cit in soil columns was reduced, due to the specific adsorption between soils and Cr(III)-cit which contained one free hydroxyl group. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Enhanced magnetization at the Cr/MgO(001) interface

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, M.-A. [Laboratoire Léon Brillouin, IRAMIS, CEA Saclay, 91191 Gif sur Yvette (France); Institut Jean Lamour, Université de Lorraine, 54500 Vandoeuvre les Nancy (France); Bataille, A. M., E-mail: alexandre.bataille@cea.fr; Ott, F. [Laboratoire Léon Brillouin, IRAMIS, CEA Saclay, 91191 Gif sur Yvette (France); Wang, Q.; Fitzsimmons, M. R. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Bertran, F.; Le Fèvre, P.; Taleb-Ibrahimi, A.; Vlad, A.; Coati, A. [Synchrotron SOLEIL, L' Orme des merisiers, 91192 Gif sur Yvette (France); Garreau, Y. [Synchrotron SOLEIL, L' Orme des merisiers, 91192 Gif sur Yvette (France); Matériaux et phénomènes quantiques (MPQ), Université Paris Diderot - Paris 7, Sorbonne-Paris-Cité, CNRS, UMR 7162, 10, rue A. Domon et L. Duquet 75205 Paris Cedex 13 (France); Hauet, T.; Andrieu, S. [Institut Jean Lamour, Université de Lorraine, 54500 Vandoeuvre les Nancy (France); Gatel, C. [CEMES-CNRS, 29 rue Jeanne Marvig, 31055 Toulouse Cedex (France)

    2015-12-21

    We report on the magnetization at the Cr/MgO interface, which we studied through two complementary techniques: angle-resolved photoemission spectroscopy and polarized neutron reflectivity. We experimentally observe an enhanced interface magnetization at the interface, yet with values much smaller than the ones reported so far by theoretical and experimental studies on Cr(001) surfaces. Our findings cast some doubts on the interpretations on previous works and could be useful in antiferromagnetic spin torque studies.

  4. Noise Performance of the CrIS Instrument

    OpenAIRE

    Zavyalov, Vladimir; Esplin, Mark; Scott, Deron; Esplin, Benjamin; Bingham, Gail; Hoffman, Erik; Lietzke, Christopher; Predina, Joseph; Frain, Rebecca; Suwinski, Lawrence; Han, Yong; Major, Charles; Graham, Brandon; Phillips, Lee

    2013-01-01

    The Cross-track Infrared Sounder (CrIS) is a spaceborne Fourier transform spectrometer (FTS) that was launched into orbit on 28 October 2011 onboard the Suomi National Polar-orbiting Partnership satellite. CrIS is a sophisticated sounding sensor that accurately measures upwelling infrared radiance at high spectral resolution. Data obtained from this sensor are used for atmospheric profiles retrieval and assimilation by numerical weather prediction models. Optimum vertical sounding resolution ...

  5. Phase stability and elastic properties of Cr-V alloys.

    Science.gov (United States)

    Gao, M C; Suzuki, Y; Schweiger, H; Doğan, Ö N; Hawk, J; Widom, M

    2013-02-20

    V is the only element in the periodic table that forms a complete solid solution with Cr and thus is particularly important in alloying strategy to ductilize Cr. This study combines first-principles density functional theory calculations and experiments to investigate the phase stability and elastic properties of Cr-V binary alloys. The cluster expansion study reveals the formation of various ordered compounds at low temperatures that were not previously known. These compounds become unstable due to the configurational entropy of bcc solid solution as the temperature is increased. The elastic constants of ordered and disordered compounds are calculated at both T = 0 K and finite temperatures. The overall trends in elastic properties are in agreement with measurements using the resonant ultrasound spectroscopy method. The calculations predict that addition of V to Cr decreases both the bulk modulus and the shear modulus, and enhances the Poisson's ratio, in agreement with experiments. Decrease in the bulk modulus is correlated to decrease in the valence electron density and increase in the lattice constant. An enhanced Poisson's ratio for bcc Cr-V alloys (compared to pure Cr) is associated with an increased density of states at the Fermi level. Furthermore, the difference charge density in the bonding region in the (110) slip plane is highest for pure Cr and decreases gradually as V is added. The present calculation also predicts a negative Cauchy pressure for pure Cr, and it becomes positive upon alloying with V. The intrinsic ductilizing effect from V may contribute, at least partially, to the experimentally observed ductilizing phenomenon in the literature.

  6. Monazite-type SrCr O4 under compression

    Science.gov (United States)

    Gleissner, J.; Errandonea, D.; Segura, A.; Pellicer-Porres, J.; Hakeem, M. A.; Proctor, J. E.; Raju, S. V.; Kumar, R. S.; Rodríguez-Hernández, P.; Muñoz, A.; Lopez-Moreno, S.; Bettinelli, M.

    2016-10-01

    We report a high-pressure study of monoclinic monazite-type SrCr O4 up to 26 GPa. Therein we combined x-ray diffraction, Raman, and optical-absorption measurements with ab initio calculations, to find a pressure-induced structural phase transition of SrCr O4 near 8-9 GPa. Evidence of a second phase transition was observed at 10-13 GPa. The crystal structures of the high-pressure phases were assigned to the tetragonal scheelite-type and monoclinic AgMn O4 -type structures. Both transitions produce drastic changes in the electronic band gap and phonon spectrum of SrCr O4 . We determined the pressure evolution of the band gap for the low- and high-pressure phases as well as the frequencies and pressure dependencies of the Raman-active modes. In all three phases most Raman modes harden under compression, however the presence of low-frequency modes which gradually soften is also detected. In monazite-type SrCr O4 , the band gap blueshifts under compression, but the transition to the scheelite phase causes an abrupt decrease of the band gap in SrCr O4 . Calculations showed good agreement with experiments and were used to better understand the experimental results. From x-ray-diffraction studies and calculations we determined the pressure dependence of the unit-cell parameters of the different phases and their ambient-temperature equations of state. The results are compared with the high-pressure behavior of other monazites, in particular PbCr O4 . A comparison of the high-pressure behavior of the electronic properties of SrCr O4 (SrW O4 ) and PbCr O4 (PbWO4) will also be made. Finally, the possible occurrence of a third structural phase transition is discussed.

  7. The Crystal Structure of SrCrO4

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    1996-01-01

    X-ray diffraction diagrams taken with Cu-K(alpha) radiation in a Bragg-Brentano diffractometer have shown that the La0.8Sr0.2CrO3 powders, synthesized by drip/spray pyrolysis in a rotating tube furnace at 600-700 oC, contained SrCrO4, in addition to the ceramic perovskite phase. By means...

  8. Cr isotope fractionation in metal-mineral-microbe interactions

    Science.gov (United States)

    Zhang, Qiong; Porcelli, Don; Thompson, Ian; Amor, Ken; Galer, Stephen

    2016-04-01

    Microbes interact with metals and minerals in the environments, altering their physical and chemical state whilst in turn the metals and minerals affect microbial growth, activity and survival. The interactions between Cr, Fe minerals and bacteria were investigated in this study. Cr(VI) reduction experiments by two iron-reducing bacteria, Pseudomonas fluorescens LB 300 and Shewanella oneidensis MR 1, in the presence of two iron oxide minerals, goethite and hematite, were conducted. Both minerals were found to inhibit the Cr(VI) reduction rate by Pseudomonas fluorescens LB 300 but accelerated Shewanella oneidensis MR 1. The Cr isotopic fractionation factor generated by both bacteria was mostly independent of the presence of the minerals, except for hematite with Pseudomonas fluorescens LB 300, where the ɛ was much higher. Aqueous Fe(III) in the solution did not have any detectable impact on either bacterial Cr reduction rates or the isotopic fractionation factors, indicating that the reduction of Cr(VI) occurred prior to that of Fe(III). The presence of aqueous Fe(II) induced a very fast abiotic reduction of Cr, but had little impact on the bacterial Cr reduction rates or its isotope fractionations. The evidence suggests that the different impact that Fe minerals had on the bacteria were related to the way they attached to the minerals and the difference in the reduction mechanism. SEM images confirmed that the attachment of Pseudomonas fluorescens LB 300 on the mineral surfaces were much more tightly packed than that of Shewanella oneidensis MR 1, so reducing mineral-metal interactions.

  9. Strength and plasticity of Fe-Cr alloys

    Science.gov (United States)

    Skripnyak, V. A.; Emelyanova, E. S.; Sergeev, M. V.; Skripnyak, N. V.; Zinovieva, O. S.

    2016-11-01

    High-chromium steels are attractive as promising structural materials for applications in nuclear facilities. Using the multilevel modeling, yield stress values of precipitation-hardened Fe-Cr steels are predicted in the temperature range up to 1115 K and pressures up to 10 GPa. The adiabatic curve obtained demonstrates a good correlation with the experimental data for a Fe-Cr-Ni alloy in the pressure range up to 10 GPa.

  10. Electronic structure and magnetic anisotropy of CrO_2

    OpenAIRE

    Toropova, A.; Kotliar, G.; Savrasov, S. Y.; Oudovenko, V. S.

    2004-01-01

    The problem of importance of strong correlations for the electronic structure, transport and magnetic properties of half--metallic ferromagnetic CrO_2 is addressed by performing density functional electronic structure calculations in the local spin density approximation (LSDA) as well as using the LSDA+U method. It is shown that the corresponding low--temperature experimental data are best fitted without accounting for the Hubbard U corrections. We conclude that the ordered phase of CrO$_2 is...

  11. Spinodal decomposition and precipitation in Cu–Cr nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Sheibani, S., E-mail: ssheibani@ut.ac.ir [School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Heshmati-Manesh, S.; Ataie, A. [School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Caballero, A.; Criado, J.M. [Instituto de Ciencia de Materiales de Sevilla and Departamento de Quimica Inorganica, CSIC – Universidad de Sevilla (Spain)

    2014-02-25

    Highlights: • Precipitation mechanism of supersaturated Cu-Cr solid solutions was investigated. • Precipitation begins with spinodal decomposition and ends with nucleation and growth. • Kinetics of decomposition is faster in presence of Al{sub 2}O{sub 3} nano-particles. -- Abstract: In this study, spinodal decomposition and precipitation mechanism of mechanically alloyed supersaturated Cu–3wt.%Cr and Cu–5wt.%Cr solid solutions was investigated under nonisothermal aging. Decomposition mechanism and kinetics were studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. Also, the microstructure was characterized by transmission electron microscopy (TEM). Effect of Al{sub 2}O{sub 3} reinforcement on the aging kinetics was also evaluated. It was found that Cu–3wt.%Cr and Cu–5wt.%Cr solid solutions undergo spinodal decomposition at initial stages of ageing. However, decomposition mechanism was changed to nucleation and growth by the aging progress. The aging kinetics for the Cu–Cr/Al{sub 2}O{sub 3} composition appeared to be slightly faster than that for Cu–Cr, since the ageing activation energy is decreased in presence of Al{sub 2}O{sub 3} nano-particles. This behavior is probably due to the higher dislocation density and other structural defects previously produced during ball milling. A detailed comparison of the DSC results with those obtained by TEM, showing good consistency, has been presented. The average size of Cr-rich precipitates was about 10 nm in the copper matrix.

  12. 操作性前提方案在生猪屠宰企业中的应用%Application of operational prerequisite program in live pig slaughtering enterprise

    Institute of Scientific and Technical Information of China (English)

    汪庆义; 朱志盈; 闵成军

    2012-01-01

    According to the IS022000 standard and actual production practice of subsidiaries of Jiangsu Yurun Meat Industry Group Co. Ltd, a set of scientific and intact operational prerequisite program that was applicable to large - scale pig slaughtering enterprises was established. The effect of operational prerequisite program was identified by detecting aerobic plate count and coliform group on the surface of carcasses of the main working procedures, pork, cutting tools and workers' hands at each working site of slaughtering and cutting line. The results showed that the hygienic condition was under control, the aerobic plate count and coliform group levels of pork reached the national standard, and the effectiveness of operational prerequisite program applied in live pig slaughtering enterprise was proved.%根据ISO22000标准的要求,并结合雨润肉类产业集团有限公司下属分子公司实际生产情况,建立一套较为科学的、完整的适用于规模化生猪屠宰企业的操作性前提方案。通过检测屠宰过程中主要工序胴体表面、分割线上猪肉、屠宰分割线上工器具及员工的手的菌落总教和大肠菌群,对建立的操作性前提方案的效果进行验证。结果表明过程卫生得到良好控制,产品茵落总数和大肠菌群指标符合国家标准,从而验证了操作性前提方案在生猪屠宰企业应用的有效性。

  13. Mechanism of Cr(VI) adsorption by coir pith studied by ESR and adsorption kinetic.

    Science.gov (United States)

    Suksabye, Parinda; Nakajima, Akira; Thiravetyan, Paitip; Baba, Yoshinari; Nakbanpote, Woranan

    2009-01-30

    The oxidation state of chromium in coir pith after Cr(VI) adsorption from aqueous solution was investigated using electron spin resonance (ESR). To elucidate the mechanism of chromium adsorption on coir pith, the adsorption studies of Cr(VI) onto lignin, alpha-cellulose and holocellulose extracted from coir pith were also studied. ESR signals of Cr(V) and Cr(III) were observed in coir pith adsorbed Cr(VI) at solution pH 2, while ESR spectra of lignin extracted from coir pith revealed only the Cr(III) signal. In addition, ESR signal of Cr(V) was observed in alpha-cellulose and holocellulose extracted from coir pith adsorbed Cr(VI). These results confirmed that lignin in coir pith reduced Cr(VI) to Cr(III) while alpha-cellulose and holocellulose extracted from coir pith reduced Cr(VI) to Cr(V). The Cr(V) signal exhibited in ESR of alpha-cellulose and holocellulose might be bound with glucose in cellulose part of coir pith. In addition, xylose which is main in pentosan part of coir pith, indicated that it is involved in form complex with Cr(V) on coir pith. The adsorption kinetic of Cr(VI) from aqueous solution on coir pith was also investigated and described well with pseudo second order model. ESR and desorption experiments confirmed that Cr(VI), Cr(V) and Cr(III), exist in coir pith after Cr(VI) adsorption. The desorption data indicated that the percentage of Cr(VI), Cr(V) and Cr(III) in coir pith were 15.63%, 12.89% and 71.48%, respectively.

  14. Mechanism of Cr(VI) adsorption by coir pith studied by ESR and adsorption kinetic

    Energy Technology Data Exchange (ETDEWEB)

    Suksabye, Parinda [Joint Graduate School of Energy and Environment, King Mongkut' s University of Technology Thonburi, 91 Pracha-Utit Road, Bangmod, Thungkru, Bangkok 10140 (Thailand); Nakajima, Akira [Division of Chemistry, Department of Medical Science, Faculty of Medicine, University of Miyazaki, Kiyotake, Miyazaki 889 1692 (Japan); Thiravetyan, Paitip [Division of Biotechnology, School of Bioresources and Technology, King Mongkut' s University of Technology Thonburi, 83 Moo.8 Thakham, Bangkhuntien, Bangkok 10150 (Thailand)], E-mail: paitip.thi@kmutt.ac.th; Baba, Yoshinari [Department of applied Chemistry, Faculty of Technology, University of Miyazaki, Gakuen-Kibabadai, Miyazaki 889 2192 (Japan); Nakbanpote, Woranan [Pilot Plant Development and Training Institute, King Mongkut' s University of Technology Thonburi, 83 Moo.8 Thakham, Bangkhuntien, Bangkok 10150 (Thailand)

    2009-01-30

    The oxidation state of chromium in coir pith after Cr(VI) adsorption from aqueous solution was investigated using electron spin resonance (ESR). To elucidate the mechanism of chromium adsorption on coir pith, the adsorption studies of Cr(VI) onto lignin, {alpha}-cellulose and holocellulose extracted from coir pith were also studied. ESR signals of Cr(V) and Cr(III) were observed in coir pith adsorbed Cr(VI) at solution pH 2, while ESR spectra of lignin extracted from coir pith revealed only the Cr(III) signal. In addition, ESR signal of Cr(V) was observed in {alpha}-cellulose and holocellulose extracted from coir pith adsorbed Cr(VI). These results confirmed that lignin in coir pith reduced Cr(VI) to Cr(III) while {alpha}-cellulose and holocellulose extracted from coir pith reduced Cr(VI) to Cr(V). The Cr(V) signal exhibited in ESR of {alpha}-cellulose and holocellulose might be bound with glucose in cellulose part of coir pith. In addition, xylose which is main in pentosan part of coir pith, indicated that it is involved in form complex with Cr(V) on coir pith. The adsorption kinetic of Cr(VI) from aqueous solution on coir pith was also investigated and described well with pseudo second order model. ESR and desorption experiments confirmed that Cr(VI), Cr(V) and Cr(III), exist in coir pith after Cr(VI) adsorption. The desorption data indicated that the percentage of Cr(VI), Cr(V) and Cr(III) in coir pith were 15.63%, 12.89% and 71.48%, respectively.

  15. Corrosion resistance of high strength modified 13Cr steel

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Mitsuo; Miyata, Yukio; Yamane, Yasuyoshi; Toyooka, Takaaki; Nakano, Yoshifumi [Kawasaki Steel Corp., Handa, Aichi (Japan). Technical Research Labs.; Murase, Fumio [Kawasaki Steel Corp., Handa, Aichi (Japan). Chita Works

    1997-08-01

    A new 13Cr martensitic stainless steel (0.025C-13Cr-Ni-Mo) with excellent resistance to CO{sub 2} corrosion and good resistance to SSC is developed and its application limit in oil and gas environments is clarified. The CO{sub 2} corrosion rate of the 13Cr steels with Ni and Mo is less than 0.3 mm/yr at 180 C (356 F) in 20% NaCl. It is less than that of the conventional 13Cr steel (0.2C-13Cr). The corrosion rate of the steel slightly decreases with the increase in Mo and Ni content. The SSC resistance improves with the increase in Mo content. The critical partial pressure of H{sub 2}S for the 2% Mo steel is greater than 0.005 MPa at the pH value of 3.5. The effects of Ni and Cu on SSC are not distinctive for this kind of steel. These results depends on the hydrogen permeability. The critical H{sub 2}S partial pressure for the 110 grade steel is the same as that of the 95 grade steel at the pH values of 4.5 and 3.0, and is slightly lower at the pH values between 3.0 and 4.5. The new 13Cr steel proves to have excellent properties in the sweet and slightly sour environment.

  16. Densities of molten Ni-(Cr, Co, W) superalloys

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; YANG Ren-hui; FANG Liang; LIU Lan-xiao; ZHAO Hong-kai

    2008-01-01

    In order to obtain more accurate density for molten Ni-(Cr, Co, W) binary alloy, the densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys were measured with a sessile drop method. It is found that the measured densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys decrease with increasing temperature in the experimental temperature range. The density of alloys increases with increasing W and Co concentrations while it decreases with increasing Cr concentration in the alloy at 1 773-1 873 K. The molar volume of Ni-based alloys increases with increasing W concentration while it decreases with increasing Co concentration. The effect of Cr concentration on the molar volume of the alloy is little in the studied concentration range. The accommodation among atomic species was analyzed. The deviation of molar volume from ideal mixing shows an ideal mixing of Ni-(Cr, Co, W) binary alloys.

  17. Thermodynamic Modeling of the Al-Cr-Mn Ternary System

    Science.gov (United States)

    Cui, Senlin; Jung, In-Ho

    2017-03-01

    The phase diagram information available in the literature on the Al-Cr-Mn system was comprehensively evaluated and optimized for the first time to obtain a set of Gibbs energies of all the solid and liquid phases in the Al-Cr-Mn system. The Modified Quasi-chemical Model (MQM) was utilized to describe the Gibbs energy of the liquid phase of the Al-Cr-Mn system. The Compound Energy Formalism (CEF) was used to model the solid solution phases. A revision of the Al-Mn system was simultaneously conducted to consider the γ_H (Al8Mn5) phase. The liquid Cr-Mn phase was also remodeled using the Modified Quasi-chemical Model (MQM) to obtain a consistent description of the ternary Al-Cr-Mn liquid phase. Accurate description of the phase diagram of the entire Al-Cr-Mn system was obtained from the thermodynamic models with optimized parameters in the present study, and the model parameters can be used to predict the thermodynamic properties of the ternary system.

  18. PRECIPITATION AND MICROSTRUCTURE OF Cr MODIFIED Al3Ti

    Institute of Scientific and Technical Information of China (English)

    W.H. Tian; M. Nemoto

    2001-01-01

    The microstructures of Cr modified Al3 Ti containing Al2 Ti and L10-AlTi precipitateshave been investigated in terms of transmission electron microscopy ( TEM). Fine pre-cipitation of Al2 Ti (Ga2Hf type structure) and L 1o-AlTi(Cr) occurs in L l2-Al3 Ti(Cr)by aging around 973K. The aging behavior was investigated by microhardness mea-surements. TEM observations revealed that plate-like Al2 Ti precipitates lie on { 100}planes of the L12-Al3 Ti(Cr) matrix with the c axis of the tetragonal phase perpendic-ular to the thin plate. As contrast with Al2 Ti precipitates, L1o-AlTi(Cr) precipitatesform thin plate and lie on {100} planes of L12-Al3Ti(Cr) matrix at the initial agingtime and for long time aging the habit plane of the thin plate deviated from {100}plane and finally formed a kinked plate. The coherency stresses across the precipi-tate/matrix interface are considered to be the main factor controlling the precipitatemorphology.``

  19. Piezomagnetism in Epitaxial Cr2O3 Thin Films

    Science.gov (United States)

    Wang, Yi; Sahoo, Sarbeswar; Binek, Christian

    2007-03-01

    Recently, the magnetoelectric material Cr2O3 attracted renewed interest due to its potential for future spintronics applications which can be realized by novel magnetic thin film heterostructures [1]. Here we study thin films of Cr2O3 (111) on c-Al2O3 (111) substrate which are grown by thermal evaporation of Cr metal in an O2 atmosphere. X-ray diffraction data reveal stoichiometric epitaxially grown Cr2O3 (111) films. Owing to a lattice mismatch of ˜4% at the interface between the Al2O3 substrate and the film we observe a strong stress induced piezomagnetic moment in the Cr2O3 film. We measure the temperature dependence of this piezomoment by Superconducting Quantum Interference Device (SQUID) magnetometry and Kerr rotation. The presence of high inherent stress, a significant piezomagnetic moment and the possibility to realize high electric fields makes our Cr2O3 thin films ideal candidates for the challenging quest of the symmetry allowed but hitherto undiscovered piezomagnetoelectric effect. [1] Ch. Binek, B. Doudin, J. Phys. Condens. Matter 17, L39 (2005).

  20. Integrated Cr(VI) removal using constructed wetlands and composting.

    Science.gov (United States)

    Sultana, Mar-Yam; Chowdhury, Abu Khayer Md Muktadirul Bari; Michailides, Michail K; Akratos, Christos S; Tekerlekopoulou, Athanasia G; Vayenas, Dimitrios V

    2015-01-08

    The present work was conducted to study integrated chromium removal from aqueous solutions in horizontal subsurface (HSF) constructed wetlands. Two pilot-scale HSF constructed wetlands (CWs) units were built and operated. One unit was planted with common reeds (Phragmites australis) and one was kept unplanted. Influent concentrations of Cr(VI) ranged from 0.5 to 10mg/L. The effect of temperature and hydraulic residence time (8-0.5 days) on Cr(VI) removal were studied. Temperature was proved to affect Cr(VI) removal in both units. In the planted unit maximum Cr(VI) removal efficiencies of 100% were recorded at HRT's of 1 day with Cr(VI) concentrations of 5, 2.5 and 1mg/L, while a significantly lower removal rate was recorded in the unplanted unit. Harvested reed biomass from the CWs was co-composted with olive mill wastes. The final product had excellent physicochemical characteristics (C/N: 14.1-14.7, germination index (GI): 145-157%, Cr: 8-10mg/kg dry mass), fulfills EU requirements and can be used as a fertilizer in organic farming. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Long-term Stability of 9- to 12 % Cr Steels

    DEFF Research Database (Denmark)

    Hald, John

    2004-01-01

    of Mo with 1.8 % W combined with a slight amount of Boron led to steel P 92. The creep rupture strength of these new alloys are now secured with long-term tests up to 100,000 hours, which demonstrate improvements of 50% (P 91), 75 % (E 911) and 100 % (P 92) in strength compared to X 20CrMoV12 1....... and pressures. Newly developed steam pipe steels are based on modifications of well-established steels like the X 20CrMoV12 1. Balanced addition of V, Nb and N to a 9Cr 1 Mo steel led to the Modified 9 Cr steel P 91. Addition of 1% W to a 9Cr 1 MoVNbN base composition led to steel E 911 and partial replacement......In the recent 25 years creep rupture strength of 9- to 12 %Cr steels for steam pipes and turbines has been doubled by development of new alloys. This development has formed a basis for improved efficiency of fossil fired steam power plants by introduction of advanced steam temperatures...

  2. High Temperature Behavior of Cr3C2-NiCr Coatings in the Actual Coal-Fired Boiler Environment

    Science.gov (United States)

    Bhatia, Rakesh; Sidhu, Hazoor Singh; Sidhu, Buta Singh

    2015-03-01

    Erosion-corrosion is a serious problem observed in steam-powered electricity generation plants, and industrial waste incinerators. In the present study, four compositions of Cr3C2-(Ni-20Cr) alloy coating powder were deposited by high-velocity oxy-fuel spray technique on T-91 boiler tube steel. The cyclic studies were performed in a coal-fired boiler at 1123 K ± 10 K (850 °C ± 10 °C). X-ray diffraction, scanning electron microscopy/energy dispersive X-ray analysis and elemental mapping analysis techniques were used to analyze the corrosion products. All the coatings deposited on T-91 boiler tube steel imparted hot corrosion resistance. The 65 pctCr3C2 -35 pct (Ni-20Cr)-coated T-91 steel sample performed better than all other coated samples in the given environment.

  3. The Exchange Coupling of Gd3+- and Cr3+-Ions in Paramagnetic GdCrO3 (In German)

    Science.gov (United States)

    Dräger, K.

    1986-03-01

    Polycrystalline samples of stoichiometric GdCrO3 have been investigated by ESR at 9.4 GHz. In the temperature range between 175 K and 520 K one broad absorption with a Lorentzian line shape and a g-factor of 2.024 has been observed. Attributing the absorption exclusively to the Gd -ion it can be shown that the temperature dependence of the ESR-intensity follows the predictions of a cluster-model. The energy describing the coupling of a single Gd3+-ion to the surrounding Cr3+-ions is found to be ΔE(Gd) = 170 cm-1. Taking advantage of the similarity within the orthochromites it is possible to determine at the same time the exchange - coupling of Cr3+-ions to their identical nearest neighbours as ΔE(Cr) = 293 cm-1. The relative strength of these couplings given by 0.60 is compatible with other experimental issues.

  4. High temperature oxidation resistance of rare earth chromite coated Fe-20Cr and Fe-20Cr-4Al alloys

    Directory of Open Access Journals (Sweden)

    Marina Fuser Pillis

    2007-09-01

    Full Text Available Doped lanthanum chromite has been used in solid oxide fuel cell (SOFC interconnects. The high costs involved in obtaining dense lanthanum chromite have increased efforts to find suitable metallic materials for interconnects. In this context, the oxidation behavior of lanthanum chromite coated Fe-20Cr and Fe-20Cr-4Al alloys at SOFC operation temperature was studied. Isothermal oxidation tests were carried out at 1000 °C for 20, 50 and 200 hours. Cyclic oxidation tests were also carried out and each oxidation cycle consisted of 7 hours at 1000/°C followed by cooling to room temperature. The oxidation measurements and the results of SEM/EDS as well as XRD analyses indicated that lanthanum chromite coated Fe-20Cr and Fe-20Cr-4Al alloys were significantly more resistant to oxidation compared with the uncoated alloys.

  5. [Effect of different heat treatment on mechanical properties and microstructure of laser welding CoCr-NiCr dissimilar alloys].

    Science.gov (United States)

    Liang, Rui-ying; Li, Chang-yi; Han, Ya-jing; Hu, Xin; Zhang, Lian-yun

    2008-11-01

    To evaluate the effect of heat treatment and porcelain-fused-to-metal (PFM) processing on mechanical properties and microstructure of laser welding CoCr-NiCr dissimilar alloys. Samples of CoCr-NiCr dissimilar alloys with 0.5 mm thickness were laser-welded single-side under the setting parameters of 280 V, 10 ms pulse duration. After being welded, samples were randomly assigned to three groups, 10 each. Group1 and 2 received heat treatment and PFM processing, respectively. Group 3 was control group without any treatment. Tensile strength, microstructure and element distribution of samples in the three groups were tested and observed using tensile test, metallographic examinations, scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) analysis. After heat treatment and PFM processing, tensile strength of the samples were (537.15 +/- 43.91) MPa and (534.58 +/- 48.47) MPa respectively, and elongation rates in Group 1 and 2 were (7.65 +/- 0.73)% and (7.40 +/- 0.45)%. Ductile structure can be found on tensile fracture surface of samples and it was more obvious in heat treatment group than in PFM group. The results of EDS analysis indicated that certain CoCr alloy diffused towards fusion zone and NiCr side after heat treatment and PFM processing. Compared with PFM processing group, the diffusion in the heat treatment group was more obvious. Heat treatment and PFM processing can improve the mechanical properties and microstructure of welded CoCr-NiCr dissimilar alloy to a certain degree. The improvements are more obvious with heat treatment than with porcelain treatment.

  6. Influence of Cr on the nanoclusters formation and superferromagnetic behavior of Fe-Cr-Nb-B glassy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chiriac, H.; Whitmore, L.; Grigoras, M.; Ababei, G.; Stoian, G.; Lupu, N., E-mail: nicole@phys-iasi.ro [National Institute of Research and Development for Technical Physics, 700050 Iasi (Romania)

    2015-05-07

    High resolution imaging and electron diffraction confirm that in the as-quenched state the structure of Fe{sub 79.7−x}Cr{sub x}Nb{sub 0.3}B{sub 20} (x = 11–13 at. %) melt-spun ribbons is completely amorphous, independent of the Cr content. Energy-dispersive X-ray spectroscopy mapping emphasizes clearly the presence of Fe and Cr clusters varying from approximately 1 to 2–3 nm in size with the increase of Cr content from 11 to 13 at. %. The Fe and Cr atoms segregate the atomic scale to form nanometer sized clusters, influencing strongly the macroscopic magnetic behavior. The Curie temperature of the system, T{sub C}{sup system}, confirmed by the magnetic susceptibility versus temperature measurements, gives the strength of the magnetic interactions between clusters. The inter-cluster interactions are much stronger for lower contents of Cr, the microstructure is less uniform, and T{sub C}{sup system} increases from 290 K for 13 at. % Cr to 330 K for 11.5 at. % Cr. The whole system transforms to a ferromagnetic state through interactions between the clusters. Zero-field cooling and field cooling curves confirm the cluster behavior with a blocking temperature, T{sub b}, of about 250 K. Above T{sub b}, the ribbons behave as a superferromagnetic system, whilst below the blocking temperature a classical ferromagnetic behavior is observed.

  7. Colour due to Cr3+ ions in oxides: a study of the model system MgO:Cr3+.

    Science.gov (United States)

    Aramburu, J A; García-Fernández, P; García-Lastra, J M; Barriuso, M T; Moreno, M

    2013-05-01

    Seeking to understand why the cubic centre in MgO:Cr(3+) has the same 10Dq value as emerald, ab initio cluster and periodic supercell calculations have been performed. It is found that the equilibrium Cr(3+)-O(2-) distance, R, in MgO:Cr(3+) is equal to 2.03 Å and thus 0.06 Å higher than that measured for the emerald. Calculations carried out on the isolated CrO(6)(9-) complex at R = 2.03 Å give 10Dq = 14,510 cm(-1), which is 10% smaller than the experimental figure for MgO:Cr(3+). Nevertheless, when the internal electric field, ER(r), due to the rest of the lattice ions is also taken into account, the calculated 10Dq = 16,210 cm(-1) coincides with the experimental value. Accordingly, the colour shift for different oxides doped with Cr(3+) can be well understood on the basis of this extrinsic contribution to 10Dq usually ignored in a ligand field description. The calculated electrostatic potential, VR(r), related to ER(r), is found to be attractive when the electronic density is lying along directions and |r| > 1 Å driven by the first shell of twelve Mg(2+) ions. The action of VR(r) upon the CrO(6)(9-) complex slightly decreases the energy of t2g(xy,xz,yz) orbitals with respect to that for eg(3z(2) - r(2),x(2) - y(2)) orbitals, thus enhancing the 10Dq value by 0.2 eV. However, the addition of VR(r) induces very small changes in the electronic density, a relevant fact that is related to the (2)E(t(2g)(3)) −> (4)A(2)(t(2g)(3)) emission energy being nearly independent of the host lattice along the series of Cr(3+)-doped oxides.

  8. Cr(Ⅵ) Absorption Bacteria: Screening and Cr(Ⅵ) Adsorption%Cr(Ⅵ)吸附菌的分离及其对Cr(Ⅵ)吸附的研究

    Institute of Scientific and Technical Information of China (English)

    张勇; 龚小宝; 孙飞

    2011-01-01

    A chromium absorption strain of bacteria was isolated and screened from Cr-contaminated soil and was identified as Bacillus sp. In a lab-scaled experiment, involving culture of the microbiological media and preparation of the bio-sorbent. Adsorption behavior of the bio-sorbent and the influence of pH, temperature and the co-existed ions and initial Cr( VI) concentration of the wastewater sample on the adsorption were studied, which resulted in the optimal Cr( VI) adsorption condition. Adsorption capacity of the bio-sorbent reached 126.57 mg/g at Langmuir, Freundlich and Dubinin-Radushkevick isotherms were applied to fitting adsorption equilibrium data, thus it was found that Langmuir isotherm adsorption model was the best reflecting the adsorption characteristics. SEM used in the study presented the images of the change of the bacteria cells surface before and after the adsorption process.%从某受铬污染的土壤中分离出一株铬吸附菌,经初步分离鉴定为芽孢杆菌。利用微生物培养基对其进行扩大培养,然后制备生物吸附剂,研究了吸附剂对Cr(Ⅵ)的吸附行为及pH、Cr(Ⅵ)初始浓度、温度和共存离子对吸附的影响。结果表明,吸附剂对Cr(Ⅵ)有较好的吸附效果,最佳吸附条件为pH=9.0,初始浓度为40mg/L,最佳温度为35℃,共存离子Zn2+降低了Cr(Ⅵ)的吸附量,Cu2+增加了吸附量。用Langmuir、Freundlich及Dubinin-Raduskevich吸附等温模型对吸附过程进行拟合发现:Langmuir模型可以很好地反映芽孢杆菌对Cr(Ⅵ)的吸附特性,在308 K时最大吸附量为126.57 mg/g;通过扫描电镜看出,菌体表面结构由疏松变紧密,较好反映了菌体表面结构的变化。研究表明,芽孢杆菌对Cr(Ⅵ)有很好的吸附效果,为Cr(Ⅵ)的去除提供了新的途径。

  9. Cr concentration dependence of overestimation of long term creep life in strength enhanced high Cr ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, K., E-mail: maruyama@material.tohoku.ac.j [Graduate School of Environmental Studies, Tohoku University, 6-6-02 Aobayama, Sendai 980-8579 (Japan); Ghassemi Armaki, H.; Chen, R.P.; Yoshimi, K. [Graduate School of Environmental Studies, Tohoku University, 6-6-02 Aobayama, Sendai 980-8579 (Japan); Yoshizawa, M.; Igarashi, M. [Corporate Research and Development Laboratories, Sumitomo Metal Industry, Ltd., 1-8 Fuso-Cho, Amagasaki 660-0891 (Japan)

    2010-06-15

    Creep rupture data and microstructural degradation during aging of high Cr ferritic boiler steels with enhanced creep strength have been studied with special attention to prediction of long term creep rupture life. Tempered lath martensite structure in the high Cr ferritic steels remains unchanged during short term aging, whereas static recovery of the lath martensite structure proceeds when diffusion distance during aging becomes sufficiently long as is the case in long term creep. The static recovery brings about premature failure in long term creep and decreases in apparent activation energy for creep life. The decrease in activation energy is responsible for overestimation of rupture life reported in strength enhanced high Cr ferritic steels. The boundary from a short term region with high activation energy Q{sub H} to a long term region with low activation energy Q{sub L} moves towards longer time with decreasing Cr concentration. The difference in activation energy (Q{sub H} - Q{sub L}) primarily determines the extent of overestimation of rupture life predicted from short term data. In general, the extent of overestimation is less serious at 9%Cr as compared to 12%Cr.

  10. Mechanical and Tribological Properties of HVOF-Sprayed (Cr3C2-NiCr+Ni) Composite Coating on Ductile Cast Iron

    Science.gov (United States)

    Ksiazek, Marzanna; Boron, Lukasz; Radecka, Marta; Richert, Maria; Tchorz, Adam

    2016-08-01

    The aim of the investigations was to compare the microstructure, mechanical, and wear properties of Cr3C2-NiCr+Ni and Cr3C2-NiCr coatings deposited by HVOF technique (the high-velocity oxygen fuel spray process) on ductile cast iron. The effect of nickel particles added to the chromium carbide coating on mechanical and wear behavior in the system of Cr 3 C 2 -NiCr+Ni/ductile cast iron was analyzed in order to improve the lifetime of coated materials. The structure with particular emphasis of characteristic of the interface in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron was studied using the optical, scanning, and transmission electron microscopes, as well as the analysis of chemical and phase composition in microareas. Experimental results show that HVOF-sprayed Cr3C2-NiCr+Ni composite coating exhibits low porosity, high hardness, dense structure with large, partially molten Ni particles and very fine Cr3C2 and Cr7C3 particles embedded in NiCr alloy matrix, coming to the size of nanocrystalline. The results were discussed in reference to examination of bending strength considering cracking and delamination in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron as well as hardness and wear resistance of the coating. The composite structure of the coating provides the relatively good plasticity of the coating, which in turn has a positive effect on the adhesion of coating to the substrate and cohesion of the composite coating (Cr3C2-NiCr+Ni) in wear conditions.

  11. Simultaneous determination of Cr(III) and Cr(VI) in tannery wastewater using low pressure ion chromatography combined with flow injection spectrophotometry

    Science.gov (United States)

    Chen, Shujuan; Zhang, Xinshen; Yu, Lingyun; Wang, Li; Li, Hui

    2012-03-01

    Trivalent and hexavalent chromium have been successfully separated and determined using low pressure ion chromatography combined with flow injection spectrophotometric analysis (LPIC-FIA). A column packed with crosslinking starch microspheres was used for on-line separation of Cr(III) from Cr(VI) in a flow-injection system because of its absorptive effect on Cr(III). To determine the concentration of Cr(III) and Cr(VI) in samples, we used 3.0 mmol/L nitric acid to elute adsorbed Cr(III) from the column and then used ceric sulfate-sulfuric acid as oxidant to convert all Cr(III) into Cr(VI). Then, Cr(VI) directly came from the samples and Cr(VI) came from Cr(III) successively formed a amaranthine complex with diphenycarbazide and the complex shows a maximum absorption at 530 nm. Analytical parameters including the concentration of eluent and oxidant solution, oxidizing temperature, length of oxidizing reaction coil, reaction coil and injection coil, interfering effects, etc., were optimized. The limit of detection was 1.25 μg/L for Cr(VI) and 3.76 μg/L for Cr(III). The linear relationship between absorption with the concentration of Cr(VI) and Cr(III) was 0.001-1.000 mg/L and 0.030-1.000 mg/L with correlation coefficients of 0.9995 and 0.9994, respectively. The relative standard deviation of Cr(VI) and Cr(III) was 1.21% and 1.66%, respectively (n = 10). Major cations and anions did not show any interference. We validated this method through certified reference materials and through measuring the recovery in tannery wastewater.

  12. Investigation of fabrication and hetero-epitaxy relationship of CoCrPt thin films grown on CrW underlayer

    Institute of Scientific and Technical Information of China (English)

    Li Song-Tian; Liu Xi; Shi Wen-Kui; Cao Jiang-Wei; Wei Fu-Lin; Wei Dan

    2009-01-01

    This paper reports that longitudinally oriented CoCrPt thin films with Cr85W15 underlayer and CoCr intermediate layer for use of giant magnetoresistance heads were fabricated by magnetron sputtering.Without CoCr intermediate layer,CoCrPt layer deposited directly on Cr85W15 underlayer which has a dominant(200)texture exhibits unexpected(10-11)texture.After introducing CoCr intermediate layer,the CoCrPt layer shifts into(1120)texture.This article studies the crystallographic hetero-epitaxy relationship between magnetic layer and underlayer in order to understand the appearance of CoCrPt(10-11)texture on(200)textured Cr underlayer and the influence of CoCr intermediate layer on the inducement of CoCrPt(11-20)texture.The CoCr intermediate layer plays a crucial role in controlling the microstructure and consequently the magnetic properties of the overlying magnetic layer.

  13. Ba3(Cr0.97(1)Te0.03(1))2TeO9: in Search of Jahn-Teller Distorted Cr(II) Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Li, Manrong; Deng, Zheng; Lapidus, Saul H.; Stephens, Peter W.; Segre, Carlo U.; Croft, Mark; Sena, Robert Paria; Hadermann, Joke; Walker, David; Greenblatt, Martha

    2016-10-17

    A novel 6H - type hexagonal perovskite Ba 3 (Cr 0.97(1) Te 0.03 (1 ) ) 2 TeO 9 was prepared at high pressure (6 GPa) and temperature ( 1 773 K). Both transmission electron microscopy and synchrotron powder x - ray diffraction data demonstrate that Ba 3 (Cr 0.97(1) Te 0.03(1) ) 2 TeO 9 crystallize s in P6 3 / mmc with face - shared (Cr 0.97(1) Te 0.03(1) )O 6 octahedral pairs interconnected with TeO 6 octahedra via corner - sharing. Structure analysis shows a mixed Cr 2+ /Cr 3+ valence state with ~ 10% Cr 2+ . The existence of Cr 2+ in Ba 3 (Cr 2+ 0.10(1) Cr 3+ 0.87(1) Te 6+ 0.03 ) 2 TeO 9 is further evidenced by x - ray absorption near edge spectr oscopy . Magnetic properties measurements show a paramagnetic response down to 4 K and a small glassy - state curvature at low temperature. In this work, the o ctahedral Cr 2+ O 6 component is stabilized in an oxide material for the first time ; the expected Jahn - Teller distortion of high - spin ( d 4 ) Cr 2+ is not found , which is attributed to the small proportion of Cr 2+ (~ 10%) and the face - sharing arrangement of CrO 6 octahedral pairs, that structu rally dis favor axial distortion.

  14. Magnetic measurements of monolayer-thickness films of Cr sandwiched by Au

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, M.B.; Sill, L.R.; Sowers, C.H.

    1985-06-01

    Calculations show ferromagnetic moments (3.1..mu../sub B/) in Au-Cr-Au sandwiches, for monolayers of Cr. The measured moment (0.41..mu../sub B/ at 2/sup 0/K) is larger in Cr monolayers than for thicker Cr samples. Results are discussed in terms of other studies of this system including those which showed superconductivity.

  15. Electrochemical Behavior of Ion-Plated TiN and Cu-Cr Coatings

    Science.gov (United States)

    1993-09-01

    results show that Cu-Cr alloys containing up to about 25 atomic percent CR consist of single phase FCC structure . The alloys containing more than 60...19), curve 4 for CuCr(40), and curve 5 for Cu-Cr(85)]. Note that Curves 1, 2, and 3 are from FCC structure , curve 4 from dual-phase structure, and

  16. MICROSTRUCTURE OF CR2O3 COATINGS ON STEEL AND THE EFFECT OF SILICON

    NARCIS (Netherlands)

    VANDENBURG, M; DEHOSSON, JTM; Burg, M. van den

    This paper concentrates on the microstructural features of steel containing 22 wt.% Cr, coated with Cr2O3 by laser processing. It turned out that after laser coating the Cr2O3 powder has completely transformed to Fe0.3Cr2.7O4 having the tetragonal distorted spinel structure. Dispersed in the coating

  17. MICROSTRUCTURE OF CR2O3 COATINGS ON STEEL AND THE EFFECT OF SILICON

    NARCIS (Netherlands)

    VANDENBURG, M; DEHOSSON, JTM; Burg, M. van den

    1994-01-01

    This paper concentrates on the microstructural features of steel containing 22 wt.% Cr, coated with Cr2O3 by laser processing. It turned out that after laser coating the Cr2O3 powder has completely transformed to Fe0.3Cr2.7O4 having the tetragonal distorted spinel structure. Dispersed in the coating

  18. STUDY ON MORPHOLOGY OF CHROMIUM IN CHILLED Cu-0.14%-2.0%Cr ALLOYS

    Institute of Scientific and Technical Information of China (English)

    H.W.Yang; Z.K.Fan

    2004-01-01

    The morphology of chromium in chilled Cu-Cr alloys with 0.14%-2.0% Cr has been studied. The results showed that eutectic Cr phase takes a fibrous shape, and pre-eutectic Cr is dendritic in the studied chilled Cu-Cr alloy. During solute treatment of the eutectic and super-eutectic Cu-Cr alloys, only part of chromium particles dissolved in copper phase,some fiber and dendritic chromium still remained. Forging before solute treatment can reduce the size of primary Cr particles, which benefits the aging structure.

  19. Study on improvement of conductivity of Cu-Cr-Zr alloys

    Institute of Scientific and Technical Information of China (English)

    LI Huaqing; XIE Shuisheng; WU Pengyue; MI Xujun

    2007-01-01

    The influence of alloying, heat treatment, and plastic working on the performance of Cu-Cr-Zr alloys was investigated. The precipitated phases were characterized as Cr, Cu51Zr14 and Cu5Zr. Cu-Cr-Zr alloys demonstrate combination properties of high strength and high conductivity after solution treatment, aging treatment, and plastic deformation. Precipitation course of Cr is the main factor that influences the conductivity of Cu-Cr-Zr alloys, while adding Zr in the alloys adjusts the orientation relationship between Cr and matrix, and tends to increase the conductivity of aged Cu-Cr-Zr alloys after deformation.

  20. TL dosimetry for quality control of CR mammography imaging systems

    Science.gov (United States)

    Gaona, E.; Nieto, J. A.; Góngora, J. A. I. D.; Arreola, M.; Enríquez, J. G. F.

    The aim of this work is to estimate the average glandular dose with thermoluminescent (TL) dosimetry and comparison with quality imaging in computed radiography (CR) mammography. For a measuring dose, the Food and Drug Administration (FDA) and the American College of Radiology (ACR) use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, full field digital mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium flourohalideE We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated X-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose greater than 3.0 mGy without demonstrating improved image quality. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement for X-rays with a HVL (0.35-0.38 mmAl) and kVp (24-26) used in quality control procedures with ACR Mammography Accreditation Phantom.

  1. Cr-rich rutile: A powerful tool for diamond exploration

    Science.gov (United States)

    Malkovets, V. G.; Rezvukhin, D. I.; Belousova, E. A.; Griffin, W. L.; Sharygin, I. S.; Tretiakova, I. G.; Gibsher, A. A.; O'Reilly, S. Y.; Kuzmin, D. V.; Litasov, K. D.; Logvinova, A. M.; Pokhilenko, N. P.; Sobolev, N. V.

    2016-11-01

    Mineralogical studies and U-Pb dating have been carried out on rutile included in peridotitic and eclogitic garnets from the Internatsionalnaya pipe, Mirny field, Siberian craton. We also describe a unique peridotitic paragenesis (rutile + forsterite + enstatite + Cr-diopside + Cr-pyrope) preserved in diamond from the Mir pipe, Mirny field. Compositions of rutile from the heavy mineral concentrates of the Internatsionalnaya pipe and rutile inclusions in crustal almandine-rich garnets from the Mayskaya pipe (Nakyn field), as well as from a range of different lithologies, are presented for comparison. Rutile from cratonic mantle peridotites shows characteristic enrichment in Cr, in contrast to lower-Cr rutile from crustal rocks and off-craton mantle. Rutile with Cr2O3 > 1.7 wt% is commonly derived from cratonic mantle, while rutiles with lower Cr2O3 may be both of cratonic and off-cratonic origin. New analytical developments and availability of standards have made rutile accessible to in situ U-Pb dating by laser ablation ICP-MS. A U-Pb age of 369 ± 10 Ma for 9 rutile grains in 6 garnets from the Internatsionalnaya pipe is consistent with the accepted eruption age of the pipe (360 Ma). The equilibrium temperatures of pyropes with rutile inclusions calculated using Ni-in-Gar thermometer range between 725 and 1030 °C, corresponding to a depth range of ca 100-165 km. At the time of entrainment in the kimberlite, garnets with Cr-rich rutile inclusions resided at temperatures well above the closure temperature for Pb in rutile, and thus U-Pb ages on mantle-derived rutile most likely record the emplacement age of the kimberlites. The synthesis of distinctive rutile compositions and U-Pb dating opens new perspectives for using rutile in diamond exploration in cratonic areas.

  2. Magnetic and electrical properties of amorphous Fe-Cr-P-C-Si

    Science.gov (United States)

    Sayouri, S.; Berraho, R.; Moustaide, A.; Benbachir, K.; Kaal, A.; Tlemçani, M.; Berrada, A.

    2003-03-01

    Magnetic and electrical properties of melt-spun amorphous Fe 100- y- zCr y(PCSi) z alloys, 4⩽ y⩽11, 19⩽ z⩽22, have been investigated. The magnetic moment, μCr, of Cr has been estimated and the magnetic coupling constants, JFe-Fe, JFe-Cr and JCr-Cr, between Fe-Fe, Fe-Cr, and Cr-Cr atoms respectively, have been evaluated using the molecular field theory of two-sublattice model. Temperature dependence of electrical resistivity of these amorphous alloys was also studied. The electrical resistivity was measured between 170 and 330 K. The alloys studied exhibit a resistivity minimum at a relatively high temperature. The temperature of resistivity minimum, Tmin, increases with increasing Cr content. The effect of Cr addition in these compounds is compared with that of Co and Ni addition on the electrical resistivity on Fe-based alloys.

  3. Ensaio e anseios crípticos, de Paulo Leminski: poesia e crítica

    Directory of Open Access Journals (Sweden)

    Lívia Mendes Pereira

    2015-07-01

    Full Text Available Quando abordamos as obras críticas de Leminski, encontramos uma grande produção sobre arte, cultura, literatura e especialmente a poesia. Neste artigo, vamos investigar Leminski como ensaísta, refletindo sobre suas leituras, convicções e, principalmente, seus anseios poéticos: quem o poeta acredita ser e o que o poeta acredita para a poesia. Através desta chave, poderemos enquadrar o seu pensamento em um contexto histórico e estético específico em que o tropicalismo, concretismo, poesia beat e marginal-70 foram acontecendo. Depois dessas investigações, vamos tentar indicar como suas convicções poéticas foram aplicadas a sua poesia, principalmente em seus poemas que expressam ideias metapoéticas. Depois disso, faremos uma seleção de metapoemas a partir do livro Distraídos Venceremos, publicado em 1987, pela editora Brasiliense. Estará sob análise algumas convicções poéticas de Leminski em sua própria poesia. Os ensaios do poeta que iremos utilizar foram compilados no livro póstumo Ensaios e Anseios crípticos, publicado pela editora Unicamp em 2011. Levando-se em conta as próprias concepções do poeta sobre poesia, pretendemos apresentar neste estudo como essas ideias estão presentes em alguns de seus poemas de caráter metapoéticos.

  4. Cavitation erosion of laser processed Fe-Cr-Mn and Fe-Cr-Co alloys

    Directory of Open Access Journals (Sweden)

    M. Szkodo

    2008-12-01

    Full Text Available Purpose: Purpose of this paper is attempt explanation how laser beam processing influence on the cavitation performance of the Fe-Cr-Mn and Fe-Cr-Co alloys. This kind of alloys are frequently used in Polish power plants to routine repairs of damaged blades working under cavitation loading.Design/methodology/approach: Padding welds of investigated alloys were tested for three cases: after laser melting, after laser heating of the solid state and without additional processing. Cw. CO2 laser was employed as a source of radiation. The rotating disk rig was used in cavitation erosion investigations. The chemical composition, microstructure, and phase identification of the processed and subjected to cavitation loading alloys were examined using light microscopy, X-ray diffractometry and scanning electron microscopy, respectively.Findings: Phase transformation for processed and unprocessed alloys was observed. Obtained results revealed that laser processing contributes to delaying of austenite → martensite phase transformation. Kinetic of this transformation is different for investigated alloys and depends on the chemical composition and applied laser processing. Research limitations/implications: Reported research ought to be completed and full cavitation curves (volume loss in time for laser beam processed alloys must be done. Practical implications: For low intensity of cavitation loading, like in field conditions laser beam processing can increase of cavitation erosion resistance of investigated alloys due to increase of hardness.Originality/value: Confirmation that creation of the transformed and hardfacing structures by laser techniques leads in many cases to considerable changes in cavitation erosion properties of the processed materials.

  5. Increased conductivities of Cr doped Al{sub 2−x}Cr{sub x}O{sub 3} powders due to band gap narrowing

    Energy Technology Data Exchange (ETDEWEB)

    Badar, Nurhanna [Centre for Nanomaterials Research, Institute of Science, Level 3 Block C, Universiti Teknologi MARA, Shah Alam, Selangor 40450 (Malaysia); School of Physics and Materials Studies, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor 40450 (Malaysia); Kamarulzaman, Norlida, E-mail: norlyk@salam.uitm.edu.my [Centre for Nanomaterials Research, Institute of Science, Level 3 Block C, Universiti Teknologi MARA, Shah Alam, Selangor 40450 (Malaysia); School of Physics and Materials Studies, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor 40450 (Malaysia); Rusdi, Roshidah; Abdul Aziz, Nor Diyana [Centre for Nanomaterials Research, Institute of Science, Level 3 Block C, Universiti Teknologi MARA, Shah Alam, Selangor 40450 (Malaysia); School of Physics and Materials Studies, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor 40450 (Malaysia); Kun Fun, Hoong [School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451 (Saudi Arabia)

    2014-03-15

    A high Cr content in the synthesized Al{sub 2−x}Cr{sub x}O{sub 3} materials was achieved via a new synthesis route, the self propagating combustion method, for investigation of the effect of Cr substitution on the electrical, optical band gap and structural characteristics of the modified Al{sub 2}O{sub 3} materials. X-ray diffraction (XRD) results showed that all the samples were pure and that Cr was successfully substituted in the crystal lattice. The cell parameters and volume are linearly dependent on the Cr content. AC impedance spectroscopy results show that conductivity of the Cr doped samples increases exponentially with Cr content. This is attributed to band gap narrowing of the Al{sub 2−x}Cr{sub x}O{sub 3} powders as obtained from UV–visible spectrophotometric studies.

  6. Simultaneous determinations of Cr(VI) and Cr(III) by ion-exclusion/cation-exchange chromatography with an unmodified silica-gel column.

    Science.gov (United States)

    Hirata, Shizuko; Kozaki, Daisuke; Sakanishi, Kinya; Nakagoshi, Nobukazu; Tanaka, Kazuhiko

    2010-01-01

    In order to characterize the ion-exclusion and cation-exchange properties of an unmodified silica-gel column, the retention behaviors of Cr(VI) and Cr(III) ions were investigated using a Develosil 30-5 (150 x 4.6 mm i.d.) in the acidic region. Cr(VI) was separated from other anions by an ion-exclusion and ion-adsorption mechanism, and Cr(III) was separated from other cations with a cation-exchange mechanism. When using 2.0 mM oxalic acid (pH 2.6) as an eluent, a good separation of Cr(VI) and Cr(III) was obtained using conductimetric detection in 12 min. The method was successfully applied to the simultaneous determinations of Cr(VI) and Cr(III) added into tap-water and river-water samples.

  7. Neutron diffraction studies of the Na-ion battery electrode materials NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3

    Science.gov (United States)

    Yahia, H. Ben; Essehli, R.; Avdeev, M.; Park, J.-B.; Sun, Y.-K.; Al-Maadeed, M. A.; Belharouak, I.

    2016-06-01

    The new compounds NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 were synthesized by sol-gel method and their crystal structures were determined by using neutron powder diffraction data. These compounds were characterized by galvanometric cycling and cyclic voltammetry. NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 crystallize with a stuffed α-CrPO4-type structure. The structure consists of a 3D-framework made of octahedra and tetrahedra that are sharing corners and/or edges generating channels along [100] and [010], in which the sodium atoms are located. Of significance, in the structures of NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 a statistical disorder Ni2+/Cr3+ was observed on both the 8g and 4a atomic positions, whereas in NaCoCr2(PO4)3 the statistical disorder Co2+/Cr3+ was only observed on the 8g atomic position. When tested as negative electrode materials, NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 delivered specific capacities of 352, 385, and 368 mA h g-1, respectively, which attests to the electrochemical activity of sodium in these compounds.

  8. Z-phase in 9-12% Cr steels

    Energy Technology Data Exchange (ETDEWEB)

    Danielsen, Hilmar; Hald, John [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Manufacturing Engineering and Management

    2004-04-01

    Precipitation of the complex nitride Z-phase Cr(Nb,V)N has recently been identified as a major cause for premature breakdown in creep strength of a number of new 9-12%Cr martensitic steels. These steels are primarily used in steam pipes and steam turbines of thermal power plants. Z-phase precipitation cancels out the beneficial effects of MX carbo-nitrides rich in V and Nb, which form the backbone of the creep strength of 9-12%Cr steels. Very little is known about the stability of Z-phase, and there are currently no means of predicting its occurrence. The development of a thermodynamic model based on the Thermo-Calc software could provide means to predict in which steels the Z-phase will appear. Ultimately this could form the basis for development of new high strength 9-12%Cr martensitic steels that would be immune to Z-phase precipitation. This could hopefully increase service parameters of future power plants and thus raise efficiency. A literature survey of the Z-phase was made in order to gather all available information for a thermodynamic model, mainly chemical composition and solution temperature of the Z-phase as a function of steel composition are of importance. The survey did not give a complete overview of the Z-phase, so heat treatment experiments and metallographic investigations were carried out to fill the identified gaps. As the model neared completion it became clear that it predicted the Z-phase to be stable in basically all 9-12%Cr steels, that contain its constituents. This also applied to steels like the X20CrMoV121 (12CrMoV), which has been in service for decades and has shown no signs of a breakdown in strength. Close inspection of this steel after very long service exposure showed the Z-phase to be present in a new version (CrVN), albeit in much smaller quantities compared with the newer steels. This effectively makes Z-phase precipitation a kinetic problem, and if its precipitation is sufficiently slow it will not affect the stability of a

  9. Gamma-ray decay of levels in /sup 53/Cr

    Energy Technology Data Exchange (ETDEWEB)

    Dickens, J.K.; Larson, D.C.

    1987-11-01

    Gamma-ray decay of levels in the stable isotope /sup 53/Cr has been studied using /sup 53/Cr(n,n'..gamma..) reactions for incident neutron energies between threshold and 10 MeV. Of the 65 gamma rays or gamma-ray groups observed for neutron interactions with /sup 53/Cr, 50 have been placed or tentatively placed among 34 levels in /sup 53/Cr up to an excitation energy of 4.36 MeV. Deduced branching ratios are in reasonable agreement with previous measurements except for decay of the E/sub x/ = 1537-keV level. For the decay of the E/sub x/ = 1537-keV level we are unable to explain variations in the branching ratios of the transition gamma rays as a function of incident neutron energy within the framework of the presently known level structure of /sup 53/Cr and suggest the possibility of a second energy level at E/sub x/ = 1537 keV. 59 refs., 13 figs., 2 tabs.

  10. Compactness of $\\Box_b$ in a CR manifold

    CERN Document Server

    Khanh, Tran Vu; Zampieri, Giuseppe

    2011-01-01

    This note is aimed at simplifying current literature about compactness estimates for the Kohn-Laplacian on CR manifolds. The approach consists in a tangential basic estimate in the formulation given by the first author in \\cite{Kh10} which refines former work by Nicoara \\cite{N06}. It has been proved by Raich \\cite{R10} that on a CR manifold of dimension $2n-1$ which is compact pseudoconvex of hypersurface type embedded in $\\C^n$ and orientable, the property named "$(CR-P_q)$" for $1\\leq q\\leq \\frac{n-1}2$, a generalization of the one introduced by Catlin in \\cite{C84}, implies compactness estimates for the Kohn-Laplacian $\\Box_b$ in degree $k$ for any $k$ satisfying $q\\leq k\\leq n-1-q$. The same result is stated by Straube in \\cite{S10} without the assumption of orientability. We regain these results by a simplified method and extend the conclusions in two directions. First, the CR manifold is no longer required to be embedded. Second, when $(CR-P_q)$ holds for $q=1$ (and, in case $n=1$, under the additional...

  11. Morphological, electronic and magnetic characterization of bulk Cr tips

    Energy Technology Data Exchange (ETDEWEB)

    Corbetta, Marco; Ouazi, Safia; Nahas, Yasmine; Oka, Hirofumi; Wedekind, Sebastian; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany); Donati, Fabio [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany); CNISM, NEMAS, Milano (Italy); Dipartimento di Energia - Politecnico di Milano, Milano (Italy)

    2011-07-01

    The most delicate task for successful SP-STM measurements is the preparation of suitable tips offering high spatial resolution, high spin polarization and negligible magnetic stray field. Nonmagnetic tips covered with an ultrathin film of antiferromagnetic material as Cr have been largely and successfully used. The main drawback of coated tips is that an in-situ preparation is required. Recently a simple and reliable method for the preparation of bulk Cr tips using only a standard electrochemical etching has been proposed. We produced and used such tips for in-field spin-polarized STM measurements at 7 K on Co nano-islands on Cu(111). We obtain stable and reliable spin-resolved imaging and spectroscopy results. We measure symmetric hysteresis loops of the differential conductance, which show that the magnetization direction of the Cr tip apex follows the external magnetic field direction. Measuring dI/dV asymmetry curves on Co islands we find that the spin polarization of bulk Cr tips can be as large as 30%, which is larger as compared to Cr/Co/W tips.

  12. Local control of antiferromagnetic domains in Cr2O3

    Science.gov (United States)

    Adenwalla, S.; Singh, Uday; Echtenkamp, W.; Binek, Ch.

    2015-03-01

    We have used a Cr2O3/Pd/(Co/Pd)3 exchange biased heterostructure to measure the spatial distribution of anti-ferromagnetic (AFM) domains in magnetoelectric AFM Cr2O3.TheAFMCr2O3 possesses a residual roughness insensitive surface magnetization below its Néel temperature (TN 307K) This surface magnetization couples to the ferromagnetic material (Co/Pd) and results in exchange bias. Cooling the Cr2O3 from above its Néel temperature in different magnetization states of the ferromagnet results in the formation of AFM domains in Cr2O3. The AFM domains in the Cr2O3 were mapped by a spatial map of the exchange bias of the ferromagnet for the sample cooled in various remnant conditions of Co/Pd and at different temperatures. Local control of AFM domains was achieved by first, controlling the magnetization of Co/Pd multilayers and cooling below the Neel temperature, resulting in a single AFM domain, and then, subsequently writing a reversed AFM domain using the heat from a 6 mW focused laser beam. Scanning the laser beam allows for the writing of any domain pattern with a spatial resolution of 5 μm, limited only by the focusing optics. This work is supported by NSF Grant No. 1409622 and MRSEC DMR-0820521.

  13. TRIBOLOGICAL PROPERTIES OF CrAgN THIN FILMS

    Directory of Open Access Journals (Sweden)

    Peter Jurči

    2013-04-01

    Full Text Available CrN and CrAgN thin films were magnetron sputtered onto the substrate made from Vanadis 6 cold work tool steel. The films were examined on tribological properties using a high temperature Pin-on-disc tribometer. Obtained results show that there is almost no effect of Ag addition on the friction coefficient when tested at a room temperature against alumina. The testing against the same counterpart at higher temperature gave positive effect of the silver addition on the friction coefficient. The testing against 100Cr6 ball bearing steel gave higher friction coefficient than that against alumina while the testing against CuSn6-bronze led to much lower μ. When tested at a room temperature, the wear performance of the films was positively affected only in the case of the CrAg3N film developed at 500 °C. On the other hand, addition of 3 wt% Ag into the CrN increased the wear performance at elevated temperatures while the addition of 15 wt% Ag has made the film too soft and sensitive to wear.

  14. Tribological properties of CrAgN thin films

    Directory of Open Access Journals (Sweden)

    Peter Jurči

    2013-02-01

    Full Text Available CrN and CrAgN thin films were magnetron sputtered onto the substrate made from Vanadis 6 cold work tool steel. The films were examined on tribological properties using a high temperature Pin-on-disc tribometer. Obtained results show that there is almost no effect of Ag addition on the friction coefficient when tested at a room temperature against alumina. The testing against the same counterpart at higher temperature gave positive effect of the silver addition on the m. The testing against 100Cr6 ball bearing steel gave higher friction coefficient than that against alumina while the testing against CuSn6-bronze led to much lower m. When tested at a room temperature, the wear performance of the films was positively affected only in the case of the CrAg3N film developed at 500 oC. On the other hand, addition of 3 wt% Ag into the CrN increased the wear performance at elevated temperatures while the addition of 15 wt% Ag has made the film too soft and sensitive to wear.

  15. Oxidation - Nitridation of Ni-Cr-Al alloys

    Directory of Open Access Journals (Sweden)

    Han Susan

    2004-01-01

    Full Text Available A series of alloys containing 24-36 wt pct Cr and 13.5 - 25.0 wt pct Al was reacted with air at 1100°C for 260 h. The products of isothermal reaction were scales of a-Al2O3 plus small amounts of Cr2O3. These grew according to parabolic kinetics, interrupted by episodic weight losses caused by partial spallation. No nitridation occurred during the isothermal exposures. Reaction during thermal cycling for up to 260 one hour cycles was much more severe. Repeated scale spallation led to subsurface alloy depletion in aluminium and, to a lesser extent, chromium. This caused transformation of the prior alloy three-phase structures (a-Cr+b-NiAl+g-Ni to single-phase g-nickel solution. Destruction of the external scale allowed gas access to this metal which was able to dissolve both oxygen and nitrogen. Inward diffusion of the two oxidants led to development of a complex internal precipitation zone: Al2O3 and Cr2O3 beneath the surface, then Al2O3 then AIN, then AIN + Cr2N and finally AIN alone in the deepest region. Diffusion-controlled kinetics were in effect initially, but mechanical damage to the internal precipitation zone led to more rapid gas access and approximately linear kinetics in the long term.

  16. Incorporation of Cr3+ in dickite: a spectroscopic study

    Science.gov (United States)

    Balan, E.; Allard, T.; Morin, G.; Calas, G.

    We have investigated a well-ordered sample of natural Cr-bearing dickite from Nowa Ruda (Lower Silesia, Poland) using electron paramagnetic resonance (EPR) at X- and Q-band frequencies (9.42 and 33.97 GHz, respectively) and optical diffuse reflectance spectroscopy. The observation of the spin-forbidden transitions at 15500 and 14690 cm-1 allows us to unambiguously identify the major contribution of octahedrally coordinated Cr3+ ions in the optical spectrum. The X- and Q-band EPR spectra show two superposed Cr3+ signals. The corresponding fine-structure parameters were determined at room temperature and 145 K. These results suggest the substitution of Cr3+ for Al3+ in equal proportions in the two unequivalent octahedral sites of the dickite structure. In kaolin group minerals, the distortion around Cr3+ ions (λ 0.2-0.4) in Al sites is significantly less rhombic than that observed around Fe3+ ions (λ 0.6-0.8).

  17. Derived Land Surface Emissivity From Suomi NPP CrIS

    Science.gov (United States)

    Zhou, Daniel K.; Larar, Allen M.; Liu, Xu

    2012-01-01

    Presented here is the land surface IR spectral emissivity retrieved from the Cross-track Infrared Sounder (CrIS) measurements. The CrIS is aboard the Suomi National Polar-orbiting Partnership (NPP) satellite launched on October 28, 2011. We describe the retrieval algorithm, demonstrate the surface emissivity retrieved with CrIS measurements, and inter-comparison with the Infrared Atmospheric Sounding Interferometer (IASI) emissivity. We also demonstrate that surface emissivity from satellite measurements can be used in assistance of monitoring global surface climate change, as a long-term measurement of IASI and CrIS will be provided by the series of EUMETSAT MetOp and US Joint Polar Satellite System (JPSS) satellites. Monthly mean surface properties are produced using last 5-year IASI measurements. A temporal variation indicates seasonal diversity and El Nino/La Nina effects not only shown on the water but also on the land. Surface spectral emissivity and skin temperature from current and future operational satellites can be utilized as a means of long-term monitoring of the Earth's environment. CrIS spectral emissivity are retrieved and compared with IASI. The difference is small and could be within expected retrieval error; however it is under investigation.

  18. Effect of microstructure on the wear resistance of borided Fe-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dybkov, Vasyl I. [Institute of Problems of Materials Science, Kyiv (Ukraine)

    2013-07-15

    Two boride layers were found to form at the interface between reacting phases in the course of boriding of Fe-Cr alloys (10, 15, 25 and 30% Cr) and chromium steels (13 and 25% Cr) in the temperature range of 850-950 C and reaction times 3600-43200 s (1-12h). In the case of Fe-10%Cr and Fe-15%Cr alloys and 13% Cr steel, the outer boride layer bordering the boriding agent consists of the (Fe,Cr)B phase, whereas the inner boride layer adjacent to the solid substrate consists of the (Fe,Cr)2B phase. Each layer is thus a homogeneous phase (type I microstructure). In contrast, on the surface of Fe-25%Cr and Fe-30%Cr alloys and 25% Cr steel each of the two boride layers consists of two phases and has a peculiar network-platelet morphology. The outer boride layer comprises the (Fe,Cr)B and (Cr,Fe)B phases, while the inner consists of the (Fe,Cr){sub 2}B and (Cr,Fe){sub 2}B phases (type II microstructure). It is such boride layers that exhibit the highest wear resistance. (orig.)

  19. Structural Investigations of Nanocrystalline Cu-Cr-Mo Alloy Prepared by High-Energy Ball Milling

    Science.gov (United States)

    Kumar, Avanish; Pradhan, Sunil Kumar; Jayasankar, Kalidoss; Debata, Mayadhar; Sharma, Rajendra Kumar; Mandal, Animesh

    2017-02-01

    Cu-Cr-Mo alloy could be a suitable candidate material for collector electrodes in high-power microwave tube devices. An attempt has been made to synthesize ternary Cu-Cr-Mo alloys by mechanical alloying of elemental Cu, Cr, and Mo powders, to extend the solid solubility of Cr and Mo in Cu, using a commercial planetary ball mill. For the first ternary alloy, a mixture of 80 wt.% Cu, 10 wt.% Cr, and 10 wt.% Mo was mechanically milled for 50 h. For the second ternary alloy, a mixture of 50 wt.% Cr and 50 wt.% Mo was mechanically milled for 50 h to obtain nanocrystalline Cr(Mo) alloy, which was later added to Cu powder and milled for 40 h to obtain Cu-20 wt.%Cr(Mo) alloy. Both nanocrystalline Cu-Cr-Mo ternary alloys exhibited crystallite size below 20 nm. It was concluded that, with addition of nanocrystalline Cr(Mo) to Cu, it was possible to extend the solid solubility of Cr and Mo in Cu, which otherwise was not possible by mechanical alloying of elemental powders. The resulting microstructure of the Cu-20 wt.%Cr(Mo) alloy comprised a homogeneous distribution of fine and hard (Cr, Mo) particles in a copper matrix. Furthermore, Cu-20 wt.%Cr(Mo) alloy showed better densification compared with Cu-10 wt.%Cr-10 wt.%Mo alloy.

  20. Stabilizing Cr species in incinerator fly ashes with/without kaolin addition through a firing process: a molecular study on heated Cr.

    Science.gov (United States)

    Wei, Yu-Ling; Wang, Hsi-Chih; Peng, Yen-Shiun

    2017-07-01

    Cr speciation in Cr-sorbing washed incinerator fly ash (IFA) after heating up to 1100°C is temperature dependent. Higher temperature leads to a greater level of chemical reduction of Cr(VI) that is considerably more toxic than Cr(III). Most Cr(VI) sorbed washed IFA is effectively transformed into Cr(III) after heating to 1100°C for 2 h, as indicated by the disappearance of hexavalent pre-edge peak of Cr K-edge X-ray absorption near edge structure (XANES) spectrum. After heating the Cr-sorbing IFA to 100°C and 500°C for 2 h, water-soluble CaCrO4 is determined to be the principal Cr species due to the chemical reaction between the sorbed Cr(VI) and CaO components of washed fly ash, based on the comparison between sample and reference XANES spectra. Replacing half of the washed fly ash with kaolin could effectively reduce all Cr(VI) after heating to ≧ 900°C for 2 h.

  1. Inlfuence of carbon content on microstructure and mechanical properties of Mn13Cr2 and Mn18Cr2 cast steels

    Institute of Scientific and Technical Information of China (English)

    Lu Dingshan; Liu Zhongyi; Li Wei

    2014-01-01

    In this paper, a comparison study was carried out to investigate the inlfuence of carbon content on the microstructure, hardness, and impact toughness of water-quenched Mn13Cr2 and Mn18Cr2 cast steels. The study results indicate that both steels' water-quenched microstructures are composed of austenite and a smal amount of carbide. The study also found that, when the carbon contents are the same, there is less carbide in Mn18Cr2 steel than in Mn13Cr2 steel. Therefore, the hardness of Mn18Cr2 steel is lower than that of Mn13Cr2 steel but the impact toughness of Mn18Cr2 steel is higher than that of Mn13Cr2 steel. With increasing the carbon content, the hardness increases and the impact toughness decreases in these two kinds of steels, and the impact toughness of Mn18Cr2 steel substantialy exceeds that of Mn13Cr2 steel. Therefore, the water-quenched Mn18Cr2 steel with high carbon content could be applied to relatively high impact abrasive working conditions, while the as-cast Mn18Cr2 steel could be only used under working conditions of relatively low impact abrasive load due to lower impact toughness.

  2. Nanostructural evolution of Cr-rich precipitates in a Cu-Cr-Zr alloy during heat treatment studied by 3 dimensional atom probe

    DEFF Research Database (Denmark)

    Hatakeyama, Masahiko; Toyama, Takeshi; Nagai, Yasuyoshi

    2008-01-01

    Nanostructural evolution of Cr (Cr-rich) precipitates in a Cu-0.78%Cr-0.13%Zr alloy has been studied after aging and overaging (reaging) by laser assisted local electrode 3 dimensional atom probe (Laser-LEAP). This material is a candidate for the first wall and divertor components of future fusion...

  3. Change in the properties of Fe-Cr-Ni and Fe-Cr-Mn austenitic steels under mixed and fast neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shamardin, V.K. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Bulanova, T.M. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Golovanov, V.N. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Neustroyev, V.S. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Povstyanko, A.V. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Ostrovsky, Z.E. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors

    1996-10-01

    Detailed investigations are performed on mechanical properties, swelling and structure of different types of Fe-Cr-Ni and Fe-Cr-Mn austenitic stainless steels irradiated in the SM-2 high-flux research reactor and BOR-60 fast reactor. Steel irradiation temperatures are ranging from 100 up to 800 C and the maximum achieved level of damage doses is 60 dpa for Fe-Cr-Mn steel (with 4-5% of Ni) and 30 dpa for steels of the C-12Cr-20Mn-W-T type. Presented are dose dependencies of swelling and mechanical properties of Fe-Cr-Ni and Fe-Cr-Mn steels. It is shown that at temperatures below 530 C the investigated Fe-Cr-Mn steel systems are less susceptible to swelling as compared to Fe-Cr-Ni ones. Fe-Cr-Mn steels showed a lower value of irradiation embrittlement after irradiation in the mixed spectrum at temperatures from 100 up to 400 C and much higher embrittlement after irradiation from 350 up to 400 C in the fast spectrum in comparison with Fe-Cr-Ni steels. Higher hardening rate of Fe-Cr-Mn steels after their irradiation in BOR-60 is attributed to the presence of dislocation loops and defects of high density in the structure. The structural change features in Fe-Cr-Mn steels under irradiation are considered taking into account austenite stabilization in the initial state. (orig.).

  4. Electron spin resonance study of a-Cr2O3 and Cr2O3·nH2O quasi-spherical nanoparticles

    CSIR Research Space (South Africa)

    Khamlich, S

    2011-12-01

    Full Text Available The quasi-spherical nanoparticles of hydrated Cr2O3 · nH2O, and crystalline -Cr2O3, have been synthesized by reduction of the first row (3d) transition metal complex of K2Cr2O7. The temperaturedependence of electron spin resonance (ESR) spectrum...

  5. Nitrate Enhanced Microbial Cr(VI) Reduction-Final Report

    Energy Technology Data Exchange (ETDEWEB)

    John F. Stolz

    2011-06-15

    A major challenge for the bioremediation of radionuclides (i.e., uranium, technetium) and metals (i.e., Cr(VI), Hg) is the co-occurrence of nitrate as it can inhibit metal transformation. Denitrification (nitrate reduction to dinitrogen gas) is considered the most important ecological process. For many metal and metalloid reducing bacteria, however, ammonia is the end product through respiratory nitrate reduction (RNRA). The focus of this work was to determine how RNRA impacts Cr(VI) transformation. The goal was to elucidate the specific mechanism(s) that limits Cr(VI) reduction in the presence of nitrate and to use this information to develop strategies that enhance Cr(VI) reduction (and thus detoxification). Our central hypothesis is that nitrate impacts the biotransformation of metals and metalloids in three ways 1) as a competitive alternative electron acceptor (inhibiting transformation), 2) as a co-metabolite (i.e., concomitant reduction, stimulating transformation), and 3) as an inducer of specific proteins and pathways involved in oxidation/reduction reactions (stimulating transformation). We have identified three model organisms, Geobacter metallireducens (mechanism 1), Sulfurospirillum barnesii, (mechasism 2), and Desulfovibrio desulfuricans (mechanisms 3). Our specific aims were to 1) investigate the role of Cr(VI) concentration on the kinetics of both growth and reduction of nitrate, nitrite, and Cr(VI) in these three organisms; 2) develop a profile of bacterial enzymes involved in nitrate transformation (e.g., oxidoreductases) using a proteomic approach; 3) investigate the function of periplasmic nitrite reductase (Nrf) as a chromate reductase; and 4) develop a strategy to maximize microbial chromium reduction in the presence of nitrate. We found that growth on nitrate by G. metallireducens was inhibited by Cr(VI). Over 240 proteins were identified by LC/MS-MS. Redox active proteins, outer membrane heavy metal efflux proteins, and chemotaxis sensory

  6. Crónicas marcianas: El triple sistema

    Directory of Open Access Journals (Sweden)

    Tatiana Herrera Ávila

    2011-11-01

    Full Text Available Este artículo aborda la colección de relatos Crónicas marcianas del escritor estadounidense Ray Bradbury y analiza los géneros literarios que se combinan en él: la ciencia ficción, la crónica y la utopía. Se demostrará cómo el texto entreteje a partir de estos géneros, una clara, abierta y a veces ácida crítica a la sociedad, una advertencia más que vigente sobre los alcances de la exploración espacial y de la aterradora posibilidad de repetir la cruel experiencia de la Conquista de América, desde una perspectiva ética y humanista.

  7. Cr-13 X/K-Cr-13 X分子筛催化剂上二氯甲烷的催化燃烧%Catalytic Combustion of Dichloromethane over Cr-13 X and K-Cr-13 X Zeolites Catalysts

    Institute of Scientific and Technical Information of China (English)

    张丽雷; 刘绍英; 李子健; 姚洁; 王公应

    2014-01-01

    Cr-13 X and K-Cr-13 X zeolites catalysts with different K and Cr contents were prepared by ion ex-change method, and their catalytic performance for catalytic combustion of dichloromethane were evaluated in a conventional fixed bed reactor. Then, these catalysts were characterized via physicochemical techniques. The results showed that, when the Cr content was less than 5.19%, crystallinity of 13X zeolite was not affec-ted by the addition of K and Cr significantly. Cr addition not only enhanced the selectivity of CO2 product, but also eliminated CH3 Cl by-products. The exchange of K with an appropriate amount enhanced the stability and activity of Cr-13X catalyst, as well as the selectivity of CO2 and HCl products. The enhancement of the cata-lytic activity and the products distribution could be accounted for the basis of oxidation and acidity of catalysts. On the condition of gas hourly space velocity of 1í104 h-1 and dichloromethane concentration of 5692 mg/m3 , an optimal 1.31%K-5.01%Cr-13X catalyst was found with t50 at 212 ℃, t98 at 298 ℃ , CO2 selectivity at 60.6% and HCl selectivity at 96.5%, and this catalyst showed relatively stable catalytic activity during 100 h reaction.%以13X分子筛为原料采用离子交换法制备了不同Cr含量的Cr-13X和K-Cr-13X分子筛催化剂,在固定床反应器上研究了催化剂对二氯甲烷的催化燃烧性能.研究结果表明, Cr含量(质量分数)小于5.19%时,对催化剂的结构没有明显影响.添加Cr提高了CO2的选择性,无CH3 Cl副产物生成.交换适量的K可以提高Cr-13X催化剂的活性和稳定性,并提高CO2和HCl的选择性.催化剂的表面酸性和氧化性是影响催化剂活性和产物分布的主要因素.在空速为1×104 h-1,二氯甲烷浓度为5692 mg/m3的条件下,1.31%K-5.01%Cr-13X分子筛催化剂对二氯甲烷催化燃烧50%的温度( t50)为212℃,燃烧98%的温度( t98)为298℃, CO2选择性为60.6%, HCl选择性为96.5%,连续反应100 h,未发现有明显失活现象.

  8. Cr(+2) Diffusion Doping in ZnSe

    Science.gov (United States)

    Journigan, Troy D.; Chen, K.-T.; Chen, H.; Burger, A.; Schaffers, K.; Page, R. H.; Payne, S. A.

    1997-01-01

    Chromium doped zinc selenides crystals have recently been demonstrated to be a promising material for near-IR room temperature tunable lasers which has an emission range of 2-3 pm. In this study, a new diffusion doping process has been developed for incorporation of Cr(+2) ion into ZnSe wafers. This process has been successfully performed under isothermal conditions, at temperatures above 800 degrees Celsius. Concentrations in excess of 10(exp 19) Cr(+2) ions/cu cm, an order of magnitude larger than previously reported in melt grown ZnSe material, have been obtained. The diffusivity was estimated to be about 10-* sq cm/sec using a classical diffusion model. Resistivity was derived from current-voltage measurements and in the 107-10(exp 16) Ohms-cm and increased as function of Cr concentration.

  9. Exchange bias in Fe/Cr double superlattices.

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, J. S.; Felcher, G. P.; Inomata, A.; Goyette, R.; Nelson, C.; Bader, S. D.

    1999-11-30

    Utilizing the oscillatory interlayer exchange coupling in Fe/Cr superlattices, we have constructed ''double superlattice'' structures where a ferromagnetic (F) and an antiferromagnetic (AF) Fe/Cr superlattice are coupled through a Cr spacer. The minor hysteresis loops in the magnetization are shifted from zero field, i.e., the F superlattice is exchange biased by the AF one. The double superlattices are sputter-deposited with (211) epitaxy and possess uniaxial in-plane magnetic anisotropy. The magnitude of the bias field is satisfactorily described by the classic formula for collinear spin structures. The coherent structure and insensitivity to atomic-scale roughness makes it possible to determine the spin distribution by polarized neutron reflectivity, which confirms that the spin structure is collinear. The magnetic reversal behavior of the double superlattices suggests that a realistic model of exchange bias needs to address the process of nucleating local reverse domains.

  10. Oxidation Behaviour of Sputtered Ni-3Cr-20Al Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The oxidation behavior of sputtered Ni-3Cr-20Al coating at 900°C in air was investigated. A dense Al2O3 layer was formed on the sputtered Ni-3Cr-20Al coating after 200 h oxidation.However, owing to the segregation of Ni3Al during oxidation Focess at high temperature, the spinel NiAl2O4 was also formed in the Al2O3 layer. It was found that the formation of NiAl2O4had no detrimental effect on the oxidation resistance of the sputtered Ni-3Cr-20Al coating due to the excellent adhesion shown by the Al2O3 and NiAl2O4 complex oxide scale.

  11. Nuclear model calculations on cyclotron production of {sup 51}Cr

    Energy Technology Data Exchange (ETDEWEB)

    Kakavand, Tayeb [Imam Khomeini International Univ., Qazvin (Iran, Islamic Republic of). Dept. of Physics; Aboudzadeh, Mohammadreza [Nuclear Science and Technology Research Institute/AEOI, Karaj (Iran, Islamic Republic of). Agricultural, Medical and Industrial Research School; Farahani, Zahra; Eslami, Mohammad [Zanjan Univ. (Iran, Islamic Republic of). Dept. of Physics

    2015-12-15

    {sup 51}Cr (T{sub 1/2} = 27.7 d), which decays via electron capture (100 %) with 320 keV gamma emission (9.8 %), is a radionuclide with still a large application in biological studies. In this work, ALICE/ASH and TALYS nuclear model codes along with some adjustments are used to calculate the excitation functions for proton, deuteron, α-particle and neutron induced on various targets leading to the production of {sup 51}Cr radioisotope. The production yields of {sup 51}Cr from various reactions are determined using the excitation function calculations and stopping power data. The results are compared with corresponding experimental data and discussed from point of view of feasibility.

  12. Dielectric behavior of Ar{sup +} implanted CR-39 polymer

    Energy Technology Data Exchange (ETDEWEB)

    Shekhawat, Nidhi; Sharma, Annu; Aggarwal, Sanjeev; Deshpande, S. K.; Nair, K. G. M. [Department of Physics, Kurukshetra University Kurukshetra-136119 (India); UGC-DAE Consortium for Scientific Research, Mumbai Centre, BARC, Mumbai 400085 (India); Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2012-06-05

    The frequency dependent dielectric response of Ar{sup +} implanted CR-39 specimens has been studied. Samples were implanted with 130 keV Ar{sup +} ions to various doses ranging from 5x10{sup 14} to 1x10{sup 16} cm{sup -2}. The frequency response of dielectric constant (e) and dielectric loss has been studied both in the pristine and argon ion implanted samples of CR-39 polymer in the frequency range 10{sup 4} to 10{sup 8} Hz. Structural changes produced in CR-39 specimens due to implantation have been studied using Attenuated total reflectance (ATR) Fourier transform infrared spectroscopic technique. Results of dielectric analysis indicate the lowering in dielectric constant ({epsilon}') and similar behavior of dielectric loss with increase in ion fluence. An attempt has been made to correlate these changes produced in the dielectric properties of implanted specimens with the structural changes produced due to implantation.

  13. Isotopic evidence of Cr partitioning into Earth's core.

    Science.gov (United States)

    Moynier, Frederic; Yin, Qing-Zhu; Schauble, Edwin

    2011-03-18

    The distribution of chemical elements in primitive meteorites (chondrites), as building blocks of terrestrial planets, provides insight into the formation and early differentiation of Earth. The processes that resulted in the depletion of some elements [such as chromium (Cr)] in the bulk silicate Earth relative to chondrites, however, remain debated between leading candidate causes: volatility versus core partitioning. We show through high-precision measurements of Cr stable isotopes in a range of meteorites, which deviate by up to ~0.4 per mil from those of the bulk silicate Earth, that Cr depletion resulted from its partitioning into Earth's core, with a preferential enrichment in light isotopes. Ab initio calculations suggest that the isotopic signature was established at mid-mantle magma ocean depth as Earth accreted planetary embryos and progressively became more oxidized.

  14. Z-phase in 9-12% Cr Steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar; Hald, John

    2004-01-01

    -phase to be stable in all of the new 9-12%Cr martensitic steels. This has generally been confirmed by the performed experiments. Z-phase precipitation seems to be a kinetic problem, and drivning force calculations using Thermo-Calc with the developed model have been used to predict steel compositions, which......The complex nitride Z-phase, Cr(V,Nb)N, has recently been identified as a major cause for premature breakdown in creep strength of a number of new 9-12%Cr martensitic steels. A thermodynamic model of the Z-phase has been created based on the Thermo-Calc software. The model predicts the Z...... will delay Z-phase precipitation....

  15. Las armas de la crítica

    Directory of Open Access Journals (Sweden)

    José Ramón Enríquez

    2015-05-01

    Full Text Available En el presente trabajo se trata de dar respuesta a las siguiente interrogantes: ¿No es, pues, la función del crítico: acompañar a la creación hasta desentrañarla, para luego recrearla en un juego múltiple, dentro del cual el espectador es otro creador...? ¿Y no es preciso, para este juego, que los tres elementos,creador, crítico y espectador, se despojen de cualquier corsé normativo y descifren los signos propios y ajenos, para la construcción de esa realidad alternativa que es el arte, que es el teatro para los aquí reunidos...? ¿Y no es su participación en este juego de múltiples creaciones, la "verdad" de la "crítica"...?

  16. Probing exotic magnetic phases and electrical transport in Cr-rich γ-NiFeCr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Pampa [S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Majumdar, A.K., E-mail: akm@bose.res.in [S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Ramakrishna Mission Vivekananda University, PO Belur Math, Howrah 711202 (India); Nigam, A.K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

    2015-05-01

    We have identified ferromagnetic, antiferromagnetic, and re-entrant spin-glass-like phases in Cr-rich γ-NiFeCr alloys and studied their critical magnetic behavior. Their electrical resistivity exhibits distinct minima between 10 and 24 K with ρ∞−√T due to electron–electron interaction effects. Electron–phonon and electron–magnon contributions to ρ are isolated. The magnetoresistance shows hysteresis effects, a signature of spin-glass-like phases and a sign reversal with change of magnetic states. We have also observed that the nature of magnetic states strongly depends on the concentration of Fe and Cr. In this system, even a small amount of Fe enhances ferromagnetism a lot while addition of a little bit of Cr suppresses ferromagnetism and takes the system to the antiferromagnetic regime. The correlation between the magnetic and the electrical properties are more meaningful here since both studies were done on the same set of samples which have rather high melting points. - Highlights: • Identified ferro, antiferro, and re-entrant spin-glass phases in Ni–Fe–Cr alloys. • Resistivity ρ~−√T shows minima from 10–24 K due to electron–electron interaction. • Electron–phonon and electron–magnon contributions to ρ are isolated. • Magneto-transport measurements strengthened the magnetic phases identified. • Correlation in magnetic/electrical properties more meaningful if same samples used.

  17. Reflexiones críticas y autocríticas sobre Pedagogía Crítica

    Directory of Open Access Journals (Sweden)

    Paz Gimeno Lorente

    2013-01-01

    Full Text Available En este breve texto, hemos querido exponer la visión que, desde Fedicaria-Aragón, tenemos sobre la situación actual del pensamiento crítico en nuestro sistema educativo. En torno a esta cuestión, se han generado algunas falacias que deseamos apuntar, ya que una educación crítica no puede desarrollarse nunca en un contexto escolar apoyado sobre unos valores hegemónicos que contradicen la finalidad de formar a unos ciudadanos críticos y rebeldes frente a las situaciones de injusticia. En este texto señalamos algunos de los condicionantes que socavan esta orientación escolar crítica, desde los que corresponden a un sistema educativo colonizado por el sistema económico, hasta los bucles político-educativos que han entrelazado una ideología seudoprogresista y una práctica neoconservadora, y que, en la actualidad, han derivado en una «plana» realidad capitalista. A pesar de ello, desde Fedicaria, pretendemos mantener una «resistencia» crítica minoritaria, espacio simbólico donde se ubica el germen de los cambios sociales.

  18. Molecular dynamics simulation of nanoindentation in Cr, Al layers and Al/Cr bilayers, using a hard spherical nanoindenter

    Directory of Open Access Journals (Sweden)

    Sebastián Amaya-Roncancio

    2014-01-01

    Full Text Available En este trabajo se realizaron simulaciones empleando dinámica molecular tridimensional aplicada a la técnica de nanoindentación, usando el método de la esfera dura en películas de Cr (bcc, Al (fcc y sistemas (Cr/Aln (n=1,2. Se empleó un potencial interatómico de Morse con el fin de describir la interacción en cada cristal y el contacto entre las estructuras de Cr y Al. Se emplearon condiciones de frontera fijas y un potencial radial repulsivo para modelar la punta esférica del indentador. Con estas condiciones se obtuvieron las propiedades mecánicas ideales a 0 K, simulando curvas de carga-descarga. Las bicapas presentaron dureza y módulo de Young altos, comparados con valores obtenidos en capas de Cr y Al. Además, la región de los átomos en movimiento después del proceso de descarga muestra un límite parabólico continuo en las capas de Al y Cr, y limites discontinuos en las bicapas, causados por las interfaces.

  19. Pack cementation Cr-Al coating of steels and Ge-doped silicide coating of Cr-Nb alloy

    Energy Technology Data Exchange (ETDEWEB)

    He, Y.R.; Zheng, M.H.; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States)

    1995-08-01

    Carbon steels or low-alloy steels used in utility boilers, heat exchangers, petrochemical plants and coal gasification systems are subjected to high temperature corrosion attack such as oxidation, sulfidation and hot corrosion. The pack cementation coating process has proven to be an economical and effective method to enhance the corrosion resistance by modifying the surface composition of steels. With the aid of a computer program, STEPSOL, pack cementation conditions to produce a ferrite Cr-Al diffusion coating on carbon-containing steels by using elemental Cr and Al powders have been calculated and experimentally verified. The cyclic oxidation kinetics for the Cr-Al coated steels are presented. Chromium silicide can maintain high oxidation resistance up to 1100{degrees}C by forming a SiO{sub 2} protective scale. Previous studies at Ohio State University have shown that the cyclic oxidation resistance of MOSi{sub 2} and TiSi{sub 2} can be further improved by Ge addition introduced during coating growth. The halide-activated pack cementation process was modified to produce a Ge-doped silicide diffusion coating in a single processing step for the ORNL-developed Cr-Nb advanced intermetallic alloy. The oxidation behavior of the silicide-coated Cr-Nb alloy was excellent: weight gain of about 1 mg/cm{sup 2} upon oxidation at 1100{degrees}C in air for 100 hours.

  20. Cr(VI) reduction and Cr(III) immobilization by Acinetobacter sp. HK-1 with the assistance of a novel quinone/graphene oxide composite.

    Science.gov (United States)

    Zhang, Hai-Kun; Lu, Hong; Wang, Jing; Zhou, Ji-Ti; Sui, Meng

    2014-11-04

    Cr(VI) biotreatment has attracted a substantial amount of interest due to its cost effectiveness and environmental friendliness. However, the slow Cr(VI) bioreduction rate and the formed organo-Cr(III) in solution are bottlenecks for biotechnology application. In this study, a novel strain, Acinetobacter sp. HK-1, capable of reducing Cr(VI) and immobilizing Cr(III) was isolated. Under optimal conditions, the Cr(VI) reduction rate could reach 3.82 mg h(-1) g cell(-1). To improve the Cr(VI) reduction rate, two quinone/graphene oxide composites (Q-GOs) were first prepared via a one-step covalent chemical reaction. The results showed that 2-amino-3-chloro-1,4-naphthoquinone-GO (NQ-GO) exhibited a better catalytic performance in Cr(VI) reduction compared to 2-aminoanthraquinone-GO. Specifically, in the presence of 50 mg L(-1) NQ-GO, a Cr(VI) removal rate of 190 mg h(-1) g cell(-1), which was the highest rate obtained, was achieved. The increased Cr(VI) reduction rate is mainly the result of NQ-GO significantly increasing the Cr(VI) reduction activity of cell membrane proteins containing dominant Cr(VI) reductases. X-ray photoelectron spectroscopy analysis found that Cr(VI) was reduced to insoluble Cr(III), which was immobilized by glycolipids secreted by strain HK-1. These findings indicate that the application of strain HK-1 and NQ-GO is a promising strategy for enhancing the treatment of Cr(VI)-containing wastewater.