Science.gov

Sample records for complexes electronic resource

  1. Electronic Resource Management and Design

    ERIC Educational Resources Information Center

    Abrams, Kimberly R.

    2015-01-01

    We have now reached a tipping point at which electronic resources comprise more than half of academic library budgets. Because of the increasing work associated with the ever-increasing number of e-resources, there is a trend to distribute work throughout the library even in the presence of an electronic resources department. In 2013, the author…

  2. Electronic Resource Management and Design

    ERIC Educational Resources Information Center

    Abrams, Kimberly R.

    2015-01-01

    We have now reached a tipping point at which electronic resources comprise more than half of academic library budgets. Because of the increasing work associated with the ever-increasing number of e-resources, there is a trend to distribute work throughout the library even in the presence of an electronic resources department. In 2013, the author…

  3. Electronic Resources for Family and Consumer Sciences.

    ERIC Educational Resources Information Center

    Goldsmith, Elizabeth B.

    1996-01-01

    Describes the following types of electronic resources relevant for family and consumer sciences: online and CD-ROM databases, numeric datafiles, and Internet resources (listservs, telnet sources, gopher/World Wide Web). (SK)

  4. Electronic Resources: A Wolf in Sheep's Clothing?

    ERIC Educational Resources Information Center

    Schaffner, Bradley L.

    2001-01-01

    Examines the impact of electronic technology on libraries and scholarship. Focuses on some of the challenges of using electronic resources in research libraries, which include cost of acquiring electronic formats and the effect such expenditures have on other library services and collection development practices. Explores how electronic resources…

  5. Electronic Resources: A Wolf in Sheep's Clothing?

    ERIC Educational Resources Information Center

    Schaffner, Bradley L.

    2001-01-01

    Examines the impact of electronic technology on libraries and scholarship. Focuses on some of the challenges of using electronic resources in research libraries, which include cost of acquiring electronic formats and the effect such expenditures have on other library services and collection development practices. Explores how electronic resources…

  6. University Facilities for Electronic Resource Systems.

    ERIC Educational Resources Information Center

    Haviland, David S.

    A report on electronic media investigates and reveals the basis for and the use of electronic resource systems on the university campus. Computer system facilities, environments, and equipment guidelines and criteria are given with the what, why and how aspects of the resource systems. The functions and categories of the university electronic…

  7. Searching Electronic Resources. Professional Growth Series.

    ERIC Educational Resources Information Center

    Pappas, Marjorie L.; And Others

    The ever-increasing availability of electronic information resources online and on CD-ROM presents library media specialists, teachers, and students with a new set of challenges for accessing information. Electronic information resources enable access to nonlinear information, which allows searchers to explore relationships and make connections…

  8. Implementing CORAL: An Electronic Resource Management System

    ERIC Educational Resources Information Center

    Whitfield, Sharon

    2011-01-01

    A 2010 electronic resource management survey conducted by Maria Collins of North Carolina State University and Jill E. Grogg of University of Alabama Libraries found that the top six electronic resources management priorities included workflow management, communications management, license management, statistics management, administrative…

  9. Implementing CORAL: An Electronic Resource Management System

    ERIC Educational Resources Information Center

    Whitfield, Sharon

    2011-01-01

    A 2010 electronic resource management survey conducted by Maria Collins of North Carolina State University and Jill E. Grogg of University of Alabama Libraries found that the top six electronic resources management priorities included workflow management, communications management, license management, statistics management, administrative…

  10. Information Skills for Electronic Resources.

    ERIC Educational Resources Information Center

    Pappas, Marjorie L.

    1995-01-01

    Discusses the importance of developing strong skills in electronic searching and stresses the importance of teaching these skills across the curriculum. Several skill models, are suggested and components of search strategies are briefly outlined. (JKP)

  11. Metadata for Electronic Information Resources

    DTIC Science & Technology

    2004-12-01

    Foundation, establishes a specific syntax for the DOI under the Handle framework. The DOI is the basis for a system called CrossRef . CrossRef is a DOI...Registration Agency formed by a consortium of electronic journal publishers. The members of CrossRef deposit their DOIs into a central repository...maintained by CrossRef . The purpose of CrossRef is to facilitate linking between electronic journals, primarily from the references at the end of an article

  12. Electronic Resource Sharing. SPEC Kit 222.

    ERIC Educational Resources Information Center

    Hogan, Donna R., Comp.; Dahlbach, Barbara J., Comp.

    The Systems and Procedures Exchange Center (SPEC) surveyed Association of Research Libraries (ARL) institutions to measure the degree of electronic resource sharing in ARL libraries; to discover which resources are being shared and between what kinds of institutions; and what documentation is available. Of the 119 ARL institutions surveyed, 53…

  13. Cataloging and Indexing of Electronic Information Resources

    DTIC Science & Technology

    2003-04-01

    Electronic Information Management for PfP Nations [La gestion electronique des informations pour les pays du PfP] To order the complete compilation...here is on electronic information resources, it should be noted that many other metadata schemes have been developed in support of e- commerce and... commerce . ONIX has elements for basic bibliographic, trade, evaluation and promotional information for books and e-books. Although initially focused on

  14. Reviewing the Electronic Resources & Libraries Conference

    ERIC Educational Resources Information Center

    Tijerina, Bonnie

    2008-01-01

    The third Electronic Resources & Libraries (ER&L) conference gathered at Georgia Institute of Technology's Global Learning and Conference Center in Atlanta, Georgia, March 18-21, 2008. Over 360 attendees, from six countries and from 80% of the United States, represented their libraries and organizations resulting in a diverse and…

  15. Reviewing the Electronic Resources & Libraries Conference

    ERIC Educational Resources Information Center

    Tijerina, Bonnie

    2008-01-01

    The third Electronic Resources & Libraries (ER&L) conference gathered at Georgia Institute of Technology's Global Learning and Conference Center in Atlanta, Georgia, March 18-21, 2008. Over 360 attendees, from six countries and from 80% of the United States, represented their libraries and organizations resulting in a diverse and…

  16. Electronic Resources: Selection and Bibliographic Control.

    ERIC Educational Resources Information Center

    Pattie, Ling-yuh W., Ed.; Cox, Bonnie Jean, Ed.

    This book is a baseline guide for professionals and library school students on issues that concern the selection and bibliographic control of electronic resources, from both conceptual and pragmatic standpoints. The book includes the following articles: (1) "Foreward" (Lois Mai Chan); (2) "Introduction" (Ling-yuh W. (Miko)…

  17. Herding Cats: Options for Organizing Electronic Resources.

    ERIC Educational Resources Information Center

    Vellucci, Sherry L.

    1996-01-01

    Examines strengths and weaknesses of organizational systems developed to organize and access electronic resources available via the Internet. Highlights include library online catalogs; cataloging rules and MARC records; text encoding initiative (TEI) headers; the Internet union catalog; browsing lists; robot-generated indexes; a core data set of…

  18. Electronic Resources: Selection and Bibliographic Control.

    ERIC Educational Resources Information Center

    Pattie, Ling-yuh W., Ed.; Cox, Bonnie Jean, Ed.

    This book is a baseline guide for professionals and library school students on issues that concern the selection and bibliographic control of electronic resources, from both conceptual and pragmatic standpoints. The book includes the following articles: (1) "Foreward" (Lois Mai Chan); (2) "Introduction" (Ling-yuh W. (Miko)…

  19. Making sense of the electronic resource marketplace: trends in health-related electronic resources.

    PubMed Central

    Blansit, B D; Connor, E

    1999-01-01

    Changes in the practice of medicine and technological developments offer librarians unprecedented opportunities to select and organize electronic resources, use the Web to deliver content throughout the organization, and improve knowledge at the point of need. The confusing array of available products, access routes, and pricing plans makes it difficult to anticipate the needs of users, identify the top resources, budget effectively, make sound collection management decisions, and organize the resources effectively and seamlessly. The electronic resource marketplace requires much vigilance, considerable patience, and continuous evaluation. There are several strategies that librarians can employ to stay ahead of the electronic resource curve, including taking advantage of free trials from publishers; marketing free trials and involving users in evaluating new products; watching and testing products marketed to the clientele; agreeing to beta test new products and services; working with aggregators or republishers; joining vendor advisory boards; benchmarking institutional resources against five to eight competitors; and forming or joining a consortium for group negotiating and purchasing. This article provides a brief snapshot of leading biomedical resources; showcases several libraries that have excelled in identifying, acquiring, and organizing electronic resources; and discusses strategies and trends of potential interest to biomedical librarians, especially those working in hospital settings. PMID:10427421

  20. From Tedious to Timely: Screencasting to Troubleshoot Electronic Resource Issues

    ERIC Educational Resources Information Center

    Hartnett, Eric; Thompson, Carole

    2010-01-01

    The shift from traditional print materials to electronic resources, in conjunction with the rise in the number of distance education programs, has left many electronic resource librarians scrambling to keep up with the resulting inundation of electronic resource problems. When it comes to diagnosing these problems, words do not always convey all…

  1. From Tedious to Timely: Screencasting to Troubleshoot Electronic Resource Issues

    ERIC Educational Resources Information Center

    Hartnett, Eric; Thompson, Carole

    2010-01-01

    The shift from traditional print materials to electronic resources, in conjunction with the rise in the number of distance education programs, has left many electronic resource librarians scrambling to keep up with the resulting inundation of electronic resource problems. When it comes to diagnosing these problems, words do not always convey all…

  2. Checklist Manifesto for Electronic Resources: Getting Ready for the Fiscal Year and Beyond

    ERIC Educational Resources Information Center

    England, Lenore; Fu, Li; Miller, Stephen

    2011-01-01

    Organization of electronic resources workflow is critical in the increasingly complicated and complex world of library management. A simple organizational tool that can be readily applied to electronic resources management (ERM) is the use of checklists. Based on the principles discussed in The Checklist Manifesto: How to Get Things Right, the…

  3. Checklist Manifesto for Electronic Resources: Getting Ready for the Fiscal Year and Beyond

    ERIC Educational Resources Information Center

    England, Lenore; Fu, Li; Miller, Stephen

    2011-01-01

    Organization of electronic resources workflow is critical in the increasingly complicated and complex world of library management. A simple organizational tool that can be readily applied to electronic resources management (ERM) is the use of checklists. Based on the principles discussed in The Checklist Manifesto: How to Get Things Right, the…

  4. Resource Letter CS-1: Complex Systems

    NASA Astrophysics Data System (ADS)

    Newman, M. E. J.

    2011-08-01

    A complex system is a system composed of many interacting parts, often called agents, which displays collective behavior that does not follow trivially from the behaviors of the individual parts. Examples include condensed-matter systems, ecosystems, stock markets and economies, biological evolution, and indeed the whole of human society. Substantial progress has been made in the quantitative understanding of complex systems, particularly since the 1980s, using a combination of basic theory, much of it derived from physics, and computer simulation. The subject is a broad one, drawing on techniques and ideas from a wide range of areas. Here, I give a selection of introductory resources, ranging from classic papers to recent books and reviews.

  5. Complex Moving Parts: Assessment Systems and Electronic Portfolios

    ERIC Educational Resources Information Center

    Larkin, Martha J.; Robertson, Royce L.

    2013-01-01

    The largest college within an online university of over 50,000 students invested significant resources in translating a complex assessment system focused on continuous improvement and national accreditation into an effective and efficient electronic portfolio (ePortfolio). The team building the system needed a model to address problems met…

  6. Constructing a dental electronic information resource (DEIR).

    PubMed

    Lang, W P

    1994-04-01

    This paper discusses the construction of a dental electronic information resource (DEIR). Development is based on the Internet gopher client/server model. Information is organized in a series of hierarchical menus. A DEIR can be browsed by traversing the menu hierarchy or by performing keyword searches. Searches can result in a menu of found items from across the Internet. Initially, contents of the DEIR will be text files. Electronic copy will be given to an editorial board that will review submissions for conformity to publication standards. A current estimate for electronic storage costs of a DEIR is $1.25/Mb per year. There will be additional costs associated with any purchases of data (e.g. Current Contents), production of data (e.g. development time), and editorial and managerial activities. The DEIR will be accessible from any computer or terminal that can connect to the Internet. Primary user groups will be faculty, staff, and students of dental schools. However, access to the DEIR will be free, and an extensive user community will be encouraged, including practicing dentists, dental associations, public health agencies, and dental insurance companies.

  7. Computational complexity in electronic structure.

    PubMed

    Whitfield, James Daniel; Love, Peter John; Aspuru-Guzik, Alán

    2013-01-14

    In quantum chemistry, the price paid by all known efficient model chemistries is either the truncation of the Hilbert space or uncontrolled approximations. Theoretical computer science suggests that these restrictions are not mere shortcomings of the algorithm designers and programmers but could stem from the inherent difficulty of simulating quantum systems. Extensions of computer science and information processing exploiting quantum mechanics has led to new ways of understanding the ultimate limitations of computational power. Interestingly, this perspective helps us understand widely used model chemistries in a new light. In this article, the fundamentals of computational complexity will be reviewed and motivated from the vantage point of chemistry. Then recent results from the computational complexity literature regarding common model chemistries including Hartree-Fock and density functional theory are discussed.

  8. Electron tunneling in respiratory complex I

    PubMed Central

    Hayashi, Tomoyuki; Stuchebrukhov, Alexei A.

    2010-01-01

    NADH:ubiquinone oxidoreductase (complex I) plays a central role in the respiratory electron transport chain by coupling the transfer of electrons from NADH to ubiquinone to the creation of the proton gradient across the membrane necessary for ATP synthesis. Here the atomistic details of electronic wiring of all Fe/S clusters in complex I are revealed by using the tunneling current theory and computer simulations; both density functional theory and semiempirical electronic structure methods were used to examine antiferromagnetically coupled spin states and corresponding tunneling wave functions. Distinct electron tunneling pathways between neighboring Fe/S clusters are identified; the pathways primarily consist of two cysteine ligands and one additional key residue. Internal water between protein subunits is identified as an essential mediator enhancing the overall electron transfer rate by almost three orders of magnitude to achieve a physiologically significant value. The identified key residues are further characterized by sensitivity of electron transfer rates to their mutations, examined in simulations, and their conservation among complex I homologues. The unusual electronic structure properties of Fe4S4 clusters in complex I explain their remarkable efficiency of electron transfer. PMID:20974925

  9. Electronic properties of complex nanostructures

    NASA Astrophysics Data System (ADS)

    Zhu, Zhen

    Nanostructured materials have brought an unprecedented opportunity for advancement in many fields of human endeavor and in applications. Nanostructures are a new research field which may revolutionize people's everyday life. In the Thesis, I have used theoretical methods including density functional theory (DFT), molecular dynamic simulations (MD) and tight-binding methods to explore the structural, mechanical and electronic properties of various nanomaterials. In all this, I also paid attention to potential applications of these findings. First, I will briefly introduce the scientific background of this Thesis, including the motivation for the study of a boron enriched aluminum surface, novel carbon foam structures and my research interest in 2D electronics. Then I will review the computational techniques I used in the study, mostly DFT methods. In Chapter 3, I introduce an effective way to enhance surface hardness of aluminum by boron nanoparticle implantation. Using boron dimers to represent the nanoparticles, the process of boron implantation is modeled in a molecular dynamics simulation of bombarding the aluminum surface by energetic B 2 molecules. Possible metastable structures of boron-coated aluminum surface are identified. Within these structures, I find that boron atoms prefer to stay in the subsurface region of aluminum. By modeling the Rockwell indentation process, boron enriched aluminum surface is found to be harder than the pristine aluminum surface by at least 15%. In Chapter 4, I discuss novel carbon structures, including 3D carbon foam and related 2D slab structures. Carbon foam contains both sp 2 and sp3 hybridized carbon atoms. It forms a 3D honeycomb lattice with a comparable stability to fullerenes, suggesting possible existence of such carbon foam structures. Although the bulk 3D foam structure is semiconducting, an sp2 terminated carbon surface could maintain a conducting channel even when passivated by hydrogen. To promote the experimental

  10. Quantum electron tunneling in respiratory complex I.

    PubMed

    Hayashi, Tomoyuki; Stuchebrukhov, Alexei A

    2011-05-12

    We have simulated the atomistic details of electronic wiring of all Fe/S clusters in complex I, a key enzyme in the respiratory electron transport chain. The tunneling current theory of many-electron systems is applied to the broken-symmetry (BS) states of the protein at the ZINDO level. While the one-electron tunneling approximation is found to hold in electron tunneling between the antiferromagnetic binuclear and tetranuclear Fe/S clusters without major orbital or spin rearrangement of the core electrons, induced polarization of the core electrons contributes significantly to decrease the electron transfer rates to 19-56 %. Calculated tunneling energy is about 3 eV higher than Fermi level in the band gap of the protein, which supports that the mechanism of electron transfer is quantum mechanical tunneling, as in the rest of the electron transport chain. Resulting electron tunneling pathways consist of up to three key contributing protein residues between neighboring Fe/S clusters. A signature of the wave properties of electrons is observed as distinct quantum interferences when multiple tunneling pathways exist. In N6a-N6b, electron tunnels along different pathways depending on the involved BS states, suggesting possible fluctuations of the tunneling pathways driven by the local protein environment. The calculated distance dependence of the electron transfer rates with internal water molecules included is in good agreement with a reported phenomenological relation.

  11. Modeling Electronic Properties of Complex Oxides

    NASA Astrophysics Data System (ADS)

    Krishnaswamy, Karthik

    Complex oxides are a class of materials that have recently emerged as potential candidates for electronic applications owing to their interesting electronic properties. The goal of this dissertation is to develop a fundamental understanding of these electronic properties using a combination of first-principles approaches based on density functional theory (DFT), and Schr odinger-Poisson (SP) simulation (Abstract shortened by ProQuest.

  12. Use of Electronic Resources in Scholarly Electronic Journals: A Citation Analysis.

    ERIC Educational Resources Information Center

    Herring, Susan Davis

    2002-01-01

    Describes a citation analysis of research articles from scholarly electronic journals published in 1999-2000 that focused on the extent to which scholars are using electronic resources and the types and subject areas of online resources that are being referenced. Results indicate a growing reliance on electronic resources, especially…

  13. Using Electronic Resources to Support Problem-Based Learning

    ERIC Educational Resources Information Center

    Chang, Chen-Chi; Jong, Ay; Huang, Fu-Chang

    2012-01-01

    Students acquire skills in problem solving and critical thinking through the process as well as team work on problem-based learning courses. Many courses have started to involve the online learning environment and integrate these courses with electronic resources. Teachers use electronic resources in their classes. To overcome the problem of the…

  14. Using Electronic Resources to Support Problem-Based Learning

    ERIC Educational Resources Information Center

    Chang, Chen-Chi; Jong, Ay; Huang, Fu-Chang

    2012-01-01

    Students acquire skills in problem solving and critical thinking through the process as well as team work on problem-based learning courses. Many courses have started to involve the online learning environment and integrate these courses with electronic resources. Teachers use electronic resources in their classes. To overcome the problem of the…

  15. The Role of the Acquisitions Librarian in Electronic Resources Management

    ERIC Educational Resources Information Center

    Pomerantz, Sarah B.

    2010-01-01

    With the ongoing shift to electronic formats for library resources, acquisitions librarians, like the rest of the profession, must adapt to the rapidly changing landscape of electronic resources by keeping up with trends and mastering new skills related to digital publishing, technology, and licensing. The author sought to know what roles…

  16. You Have "How Many" Spreadsheets? Rethinking Electronic Resource Management

    ERIC Educational Resources Information Center

    Rux, Erika; Borchert, Theresa

    2010-01-01

    As libraries face a veritable explosion of electronic resources and as the interconnectedness of print and online resources becomes increasingly complicated, many librarians are challenged to find efficient and cost-friendly ways to manage these resources. In this article, the authors describe how a team of people from various library departments…

  17. You Have "How Many" Spreadsheets? Rethinking Electronic Resource Management

    ERIC Educational Resources Information Center

    Rux, Erika; Borchert, Theresa

    2010-01-01

    As libraries face a veritable explosion of electronic resources and as the interconnectedness of print and online resources becomes increasingly complicated, many librarians are challenged to find efficient and cost-friendly ways to manage these resources. In this article, the authors describe how a team of people from various library departments…

  18. The Electronic Structure of Heavy Element Complexes

    SciTech Connect

    Bursten, Bruce E.

    2000-07-25

    The area of study is the bonding in heavy element complexes, and the application of more sophisticated electronic structure theories. Progress is recounted in several areas: (a) technological advances and current methodologies - Relativistic effects are extremely important in gaining an understanding of the electronic structure of compounds of the actinides, transactinides, and other heavy elements. Therefore, a major part of the continual benchmarking was the proper inclusion of the appropriate relativistic effects for the properties under study. (b) specific applications - These include organoactinide sandwich complexes, CO activation by actinide atoms, and theoretical studies of molecules of the transactinide elements. Finally, specific directions in proposed research are described.

  19. Complex structures of dense lithium: Electronic origin

    NASA Astrophysics Data System (ADS)

    Degtyareva, V. F.

    2016-11-01

    Lithium—the lightest alkali metal exhibits unexpected structures and electronic behavior at high pressures. Like the heavier alkali metals, Li is bcc at ambient pressure and transforms first to fcc (at 7.5 GPa). The post-fcc high-pressure form Li-cI 16 (at 40-60 GPa) is similar to Na-cI 16 and related to more complex structures of heavy alkalis Rb-oC52 and Cs- oC84. The other high pressure phases for Li (oC88, oC40, oC24) observed at pressures up to 130 GPa are found only in Li. The different route of Li high-pressure structures correlates with its special electronic configuration containing the only 3 electrons (at 1s and 2s levels). Crystal structures for Li are analyzed within the model of Fermi sphere-Brillouin zone interactions. Stability of post-fcc structures for Li are supported by the Hume-Rothery arguments when new diffraction plains appear close to the Fermi level producing pseudogaps near the Fermi level and decreasing the crystal energy. The filling of Brillouin-Jones zones by electron states for a given structure defines the physical properties as optical reflectivity, electrical resistivity and superconductivity. To understand the complexity of structural and physical properties of Li above 60 GPa it is necessary to assume the valence electron band overlap with the core electrons and increase the valence electron count under compression.

  20. Do GPs use electronic mental health resources? - a qualitative study.

    PubMed

    Austin, David; Pier, Ciaran; Mitchell, Joanna; Schattner, Peter; Wade, Victoria; Pierce, David; Klein, Britt

    2006-05-01

    The Better Outcomes in Mental Health Care (BOMHC) initiative encourages general practitioners to use electronic mental health resources (EMHRs) during consultation with patients requiring psychological assistance. However, there is little data on GPs' acceptance and use of EMHRs. Semistructured interviews were conducted with 27 GPs to determine their attitude toward EMHRs, and their use during consultation with patients. Few GPs reported frequently using EMHRs in consultation. Identified barriers to use included lack of familiarity with information technology, and insufficient knowledge of available resources. Identified advantages of electronic resources included high patient acceptance, time efficiency, and improved quality of information. General practitioners recognise several advantages of utilising electronic resources for managing patients with mental illness. However, GPs are not sufficiently familiar with electronic resources to use them effectively. This could be overcome by education.

  1. Electronic Media: A Motif for Shared Resources.

    ERIC Educational Resources Information Center

    Lightner, Stanley L.; Johnson, W. C.

    2000-01-01

    A survey of trade and industrial education supervisors from 10 states determined the degree of use of electronic education methods. Instructors in these states used presentation software and web-based exercises most often; fewer used video, CD-ROM, and distance technologies; 70% had been taught electronic presentation methods in preservice or…

  2. Electronic Media: A Motif for Shared Resources.

    ERIC Educational Resources Information Center

    Lightner, Stanley L.; Johnson, W. C.

    2000-01-01

    A survey of trade and industrial education supervisors from 10 states determined the degree of use of electronic education methods. Instructors in these states used presentation software and web-based exercises most often; fewer used video, CD-ROM, and distance technologies; 70% had been taught electronic presentation methods in preservice or…

  3. Complexity in electronic negotiation support systems.

    PubMed

    Griessmair, Michele; Strunk, Guido; Vetschera, Rudolf; Koeszegi, Sabine T

    2011-10-01

    It is generally acknowledged that the medium influences the way we communicate and negotiation research directs considerable attention to the impact of different electronic communication modes on the negotiation process and outcomes. Complexity theories offer models and methods that allow the investigation of how pattern and temporal sequences unfold over time in negotiation interactions. By focusing on the dynamic and interactive quality of negotiations as well as the information, choice, and uncertainty contained in the negotiation process, the complexity perspective addresses several issues of central interest in classical negotiation research. In the present study we compare the complexity of the negotiation communication process among synchronous and asynchronous negotiations (IM vs. e-mail) as well as an electronic negotiation support system including a decision support system (DSS). For this purpose, transcripts of 145 negotiations have been coded and analyzed with the Shannon entropy and the grammar complexity. Our results show that negotiating asynchronically via e-mail as well as including a DSS significantly reduces the complexity of the negotiation process. Furthermore, a reduction of the complexity increases the probability of reaching an agreement.

  4. Electronic neural network for dynamic resource allocation

    NASA Technical Reports Server (NTRS)

    Thakoor, A. P.; Eberhardt, S. P.; Daud, T.

    1991-01-01

    A VLSI implementable neural network architecture for dynamic assignment is presented. The resource allocation problems involve assigning members of one set (e.g. resources) to those of another (e.g. consumers) such that the global 'cost' of the associations is minimized. The network consists of a matrix of sigmoidal processing elements (neurons), where the rows of the matrix represent resources and columns represent consumers. Unlike previous neural implementations, however, association costs are applied directly to the neurons, reducing connectivity of the network to VLSI-compatible 0 (number of neurons). Each row (and column) has an additional neuron associated with it to independently oversee activations of all the neurons in each row (and each column), providing a programmable 'k-winner-take-all' function. This function simultaneously enforces blocking (excitatory/inhibitory) constraints during convergence to control the number of active elements in each row and column within desired boundary conditions. Simulations show that the network, when implemented in fully parallel VLSI hardware, offers optimal (or near-optimal) solutions within only a fraction of a millisecond, for problems up to 128 resources and 128 consumers, orders of magnitude faster than conventional computing or heuristic search methods.

  5. Improving Electronic Resources through Holistic Budgeting

    ERIC Educational Resources Information Center

    Kusik, James P.; Vargas, Mark A.

    2009-01-01

    To establish a more direct link between its collections and the educational goals of Saint Xavier University, the Byrne Memorial Library has adopted a "holistic" approach to collection development. This article examines how traditional budget practices influenced the library's selection of resources and describes how holistic collection…

  6. Electronic spectroscopy of the Al +-Ar complex

    NASA Astrophysics Data System (ADS)

    Lei, Jie; Dagdigian, Paul J.

    1999-05-01

    The laser fluorescence excitation spectrum of the Al +-Ar complex near the Al + ion 3s3p 1P ← 3s 2 1S resonance transition is reported. An excited-state ( v', 0) progression and the (0, 1) hot band were observed. Rotational analysis revealed that these bands involve an electronic transition from the Al +-Ar X 1Σ+ ground state to the 1Σ+ state correlating with the Al +( 1P)+Ar asymptote. Rotational constants and upper-state vibrational constants and the dissociation energy were determined. The spectroscopic constants of the two observed Al +-Ar electronic states are compared with those for neutral AlAr states.

  7. Extended resource allocation index for link prediction of complex network

    NASA Astrophysics Data System (ADS)

    Liu, Shuxin; Ji, Xinsheng; Liu, Caixia; Bai, Yi

    2017-08-01

    Recently, a number of similarity-based methods have been proposed to predict the missing links in complex network. Among these indices, the resource allocation index performs very well with lower time complexity. However, it ignores potential resources transferred by local paths between two endpoints. Motivated by the resource exchange taking places between endpoints, an extended resource allocation index is proposed. Empirical study on twelve real networks and three synthetic dynamic networks has shown that the index we proposed can achieve a good performance, compared with eight mainstream baselines.

  8. Negotiating two electronic resources for nursing.

    PubMed

    Kirkpatrick, J; Kuipers, J

    1995-07-01

    The five primary knowledge resource databases available in the Virginia Henderson International Library are reviewed and other menu items are discussed including library services currently under development. This article guides nurse managers to access the library on their own computer. In addition, the opportunities and advantages of the new On-line Journal of Knowledge Synthesis for Nursing are related and requirements for accessing the journal are outlined.

  9. Integrating Print and Electronic Resources: Joyner Library's "Pirate Source"

    ERIC Educational Resources Information Center

    Nall, Clark; Lewis, Janice Steed

    2005-01-01

    Valuable information in print is often neglected because of the rapid proliferation of electronic resources and the bias of many library users against print sources. At Joyner Library, it was decided to construct an interactive subject guide database that included resources in all formats to offer users a convenient starting point for research and…

  10. Using XML technologies to organize electronic reference resources.

    PubMed

    Huser, Vojtech; Del Fiol, Guilherme; Rocha, Roberto A

    2005-01-01

    Provision of access to reference electronic resources to clinicians is becoming increasingly important. We have created a framework for librarians to manage access to these resources at an enterprise level, rather than at the individual hospital libraries. We describe initial project requirements, implementation details, and some preliminary results.

  11. Complexity in Strongly Correlated Electronic Systems

    SciTech Connect

    Dagotto, Elbio R

    2005-01-01

    A wide variety of experimental results and theoretical investigations in recent years have convincingly demonstrated that several transition metal oxides and other materials have dominant states that are not spatially homogeneous. This occurs in cases in which several physical interactions - spin, charge, lattice, and/or orbital - are simultaneously active. This phenomenon causes interesting effects, such as colossal magnetoresistance, and it also appears crucial to understand the high-temperature superconductors. The spontaneous emergence of electronic nanometer-scale structures in transition metal oxides, and the existence of many competing states, are properties often associated with complex matter where nonlinearities dominate, such as soft materials and biological systems. This electronic complexity could have potential consequences for applications of correlated electronic materials, because not only charge (semiconducting electronic), or charge and spin (spintronics) are of relevance, but in addition the lattice and orbital degrees of freedom are active, leading to giant responses to small perturbations. Moreover, several metallic and insulating phases compete, increasing the potential for novel behavior.

  12. Resource letter EPA-1: Electronic polymers and their applications

    NASA Astrophysics Data System (ADS)

    Blatchford, J. W.; Epstein, A. J.

    1996-02-01

    This Resource Letter provides a guide to the literature on electronic polymers and their potential applications. Journal articles and books are cited for the following topics: (i) theories of the electronic structure and excited states of conjugated polymers, the role of electron-phonon and electron-electron interactions in determining these states, the mechanisms of charge transport, and the insulator-metal transition; (ii) information on the synthesis, structure, and morphology of representative polymers; (iii) results of transport, optical, and magnetic measurements on both conductive and semiconducting/insulating materials; and (iv) solid state device and other applications for conjugated polymers.

  13. Filling the Assurance Gap on Complex Electronics

    NASA Technical Reports Server (NTRS)

    Plastow, Richard A.

    2007-01-01

    Many of the methods used to develop software bare a close resemblance to Complex Electronics (CE) development. CE are now programmed to perform tasks that were previously handled by software, such as communication protocols. For example, the James Webb Space Telescope will use Field Programmable Gate Arrays (FPGAs), which can have over a million logic gates, to send telemetry. System-on-chip (SoC) devices, another type of complex electronics, can combine a microprocessor, input and output channels, and sometimes an FPGA for programmability. With this increased intricacy, the possibility of software-like bugs such as incorrect design, logic, and unexpected interactions within the logic is great. Since CE devices are obscuring the hardware/software boundary, mature software methodologies have been proposed, with slight modifications, to develop these devices. By using standardized S/W Engineering methods such as checklists, missing requirements and bugs can be detected earlier in the development cycle, thus creating a development process for CE that can be easily maintained and configurable based on the device used.

  14. Software Process Assurance for Complex Electronics (SPACE)

    NASA Technical Reports Server (NTRS)

    Plastow, Richard A.

    2007-01-01

    Complex Electronics (CE) are now programmed to perform tasks that were previously handled in software, such as communication protocols. Many of the methods used to develop software bare a close resemblance to CE development. For instance, Field Programmable Gate Arrays (FPGAs) can have over a million logic gates while system-on-chip (SOC) devices can combine a microprocessor, input and output channels, and sometimes an FPGA for programmability. With this increased intricacy, the possibility of software-like bugs such as incorrect design, logic, and unexpected interactions within the logic is great. Since CE devices are obscuring the hardware/software boundary, we propose that mature software methodologies may be utilized with slight modifications in the development of these devices. Software Process Assurance for Complex Electronics (SPACE) is a research project that looks at using standardized S/W Assurance/Engineering practices to provide an assurance framework for development activities. Tools such as checklists, best practices and techniques can be used to detect missing requirements and bugs earlier in the development cycle creating a development process for CE that will be more easily maintained, consistent and configurable based on the device used.

  15. Software Process Assurance for Complex Electronics

    NASA Technical Reports Server (NTRS)

    Plastow, Richard A.

    2007-01-01

    Complex Electronics (CE) now perform tasks that were previously handled in software, such as communication protocols. Many methods used to develop software bare a close resemblance to CE development. Field Programmable Gate Arrays (FPGAs) can have over a million logic gates while system-on-chip (SOC) devices can combine a microprocessor, input and output channels, and sometimes an FPGA for programmability. With this increased intricacy, the possibility of software-like bugs such as incorrect design, logic, and unexpected interactions within the logic is great. With CE devices obscuring the hardware/software boundary, we propose that mature software methodologies may be utilized with slight modifications in the development of these devices. Software Process Assurance for Complex Electronics (SPACE) is a research project that used standardized S/W Assurance/Engineering practices to provide an assurance framework for development activities. Tools such as checklists, best practices and techniques were used to detect missing requirements and bugs earlier in the development cycle creating a development process for CE that was more easily maintained, consistent and configurable based on the device used.

  16. Electronic structures of ytterbocene-imine complexes

    SciTech Connect

    Da Re, R. E.; Kuehl, C. J.; John, K. D.; Morris, D. E.

    2004-01-01

    The electronic structures of complexes of the form [(C{sub 5}Me{sub 5}){sub 2}Yb(L)]{sup +/0} (L = bipyridine, phenanthroline, terpyridine) have been probed using cyclic voltammetry and electronic spectroscopy. Remarkably, the voltammetric data reveal that the imine-based LUMO is stabilized and the redox-active metal f orbital is destabilized by ca. 1 V each upon formation of the ytterbocene-imine adduct, which is presumably responsible for the [(f){sup 13}({pi}*(L)){sup 1}] charge-transfer ground state characteristic of these complexes. The ca. 0.8 V separation between ligand-based oxidation and metal-based reduction waves for each ytterbocene adduct correlates with the energy of its optically promoted {pi}*(L)-f(Yb) charge transfer (LMCT) transition (ca. 5000 cm{sup -1}). The coupling between this LMCT excited state and the {sup 2}F{sub 7/2} ground and {sup 2}F{sub 5/2} excited states of Yb(III) leads to unusually large intensities ({var_epsilon} {approx} 1000) for the metal-localized f-f bands, which will be discussed in the context of an intensity borrowing mechanism that invokes exchange between the ligand-based {sup 2}S and metal-based {sup 2}F spin states.

  17. Evaluating Electronic Resources: Personal Development Planning Resources at the Open University, a Case Study

    ERIC Educational Resources Information Center

    Jelfs, Anne; Kelly, Patrick

    2007-01-01

    This paper discusses the evaluation of Web-based tools to support Personal Development Planning (PDP) in order to illustrate issues associated with the introduction and assessment of the effectiveness of online resources. The aims of the evaluation were based on concerns about the very complex situation that offering online resources including PDP…

  18. Coastal resource complexes of South India: options for sustainable management.

    PubMed

    Damodaran, A

    2006-04-01

    India's coastal resource complexes were traditionally characterized by a continuum of 'common property resources' or 'commons' that stretched from the shores to the seas. The continuum aided the existence of sustainable livelihood systems for local communities. Today, fragmented policy approaches and economic welfare schemes have caused the disintegration of community control over the continuum. As a consequence, livelihood systems of local communities have declined. The introduction of coastal management guidelines in the 1990s has exacerbated the situation. With reference to a coastal village located in the State of Kerala in South West India, the paper describes the trajectory of unsustainable change that has taken place in the coastal area resource complexes of the country. The paper argues for restoring the continuum of commons in the study area through community driven systems of natural resource management that are based on networks of nested institutions.

  19. Interweaving Knowledge Resources to Address Complex Environmental Health Challenges

    PubMed Central

    Anderson, Beth Ellen; Suk, William A.

    2015-01-01

    Background Complex problems do not respect academic disciplinary boundaries. Environmental health research is complex and often moves beyond these boundaries, integrating diverse knowledge resources to solve such challenges. Here we describe an evolving paradigm for interweaving approaches that integrates widely diverse resources outside of traditional academic environments in full partnerships of mutual respect and understanding. We demonstrate that scientists, social scientists, and engineers can work with government agencies, industry, and communities to interweave their expertise into metaphorical knowledge fabrics to share understanding, resources, and enthusiasm. Objective Our goal is to acknowledge and validate how interweaving research approaches can contribute to research-driven, solution-oriented problem solving in environmental health, and to inspire more members of the environmental health community to consider this approach. Discussion The National Institutes of Health’s National Institute of Environmental Health Sciences Superfund Research Program (SRP), as mandated by Congress, has evolved to become a program that reaches across a wide range of knowledge resources. SRP fosters interweaving multiple knowledge resources to develop innovative multidirectional partnerships for research and training. Here we describe examples of how motivation, ideas, knowledge, and expertise from different people, institutions, and agencies can integrate to tackle challenges that can be as complex as the resources they bring to bear on it. Conclusions By providing structure for interweaving science with its stakeholders, we are better able to leverage resources, increase potential for innovation, and proactively ensure a more fully developed spectrum of beneficial outcomes of research investments. Citation Anderson BE, Naujokas MF, Suk WA. 2015. Interweaving knowledge resources to address complex environmental health challenges. Environ Health Perspect 123:1095–1099

  20. Direct electronic probing of biological complexes formation

    NASA Astrophysics Data System (ADS)

    Macchia, Eleonora; Magliulo, Maria; Manoli, Kyriaki; Giordano, Francesco; Palazzo, Gerardo; Torsi, Luisa

    2014-10-01

    Functional bio-interlayer organic field - effect transistors (FBI-OFET), embedding streptavidin, avidin and neutravidin as bio-recognition element, have been studied to probe the electronic properties of protein complexes. The threshold voltage control has been achieved modifying the SiO2 gate diaelectric surface by means of the deposition of an interlayer of bio-recognition elements. A threshold voltage shift with respect to the unmodified dielectric surface toward more negative potential values has been found for the three different proteins, in agreement with their isoelectric points. The relative responses in terms of source - drain current, mobility and threshold voltage upon exposure to biotin of the FBI-OFET devices have been compared for the three bio-recognition elements.

  1. Redesign of Library Workflows: Experimental Models for Electronic Resource Description.

    ERIC Educational Resources Information Center

    Calhoun, Karen

    This paper explores the potential for and progress of a gradual transition from a highly centralized model for cataloging to an iterative, collaborative, and broadly distributed model for electronic resource description. The purpose is to alert library managers to some experiments underway and to help them conceptualize new methods for defining,…

  2. Technical Communicator: A New Model for the Electronic Resources Librarian?

    ERIC Educational Resources Information Center

    Hulseberg, Anna

    2016-01-01

    This article explores whether technical communicator is a useful model for electronic resources (ER) librarians. The fields of ER librarianship and technical communication (TC) originated and continue to develop in relation to evolving technologies. A review of the literature reveals four common themes for ER librarianship and TC. While the…

  3. Electronic Commerce Resource Centers. An Industry--University Partnership.

    ERIC Educational Resources Information Center

    Gulledge, Thomas R.; Sommer, Rainer; Tarimcilar, M. Murat

    1999-01-01

    Electronic Commerce Resource Centers focus on transferring emerging technologies to small businesses through university/industry partnerships. Successful implementation hinges on a strategic operating plan, creation of measurable value for customers, investment in customer-targeted training, and measurement of performance outputs. (SK)

  4. Electronic Commerce Resource Centers. An Industry--University Partnership.

    ERIC Educational Resources Information Center

    Gulledge, Thomas R.; Sommer, Rainer; Tarimcilar, M. Murat

    1999-01-01

    Electronic Commerce Resource Centers focus on transferring emerging technologies to small businesses through university/industry partnerships. Successful implementation hinges on a strategic operating plan, creation of measurable value for customers, investment in customer-targeted training, and measurement of performance outputs. (SK)

  5. Pricing of Electronic Resources: Interviews with Three Vendors.

    ERIC Educational Resources Information Center

    Abels, Eileen G.

    1996-01-01

    Interviews with three vendors of electronic resources provide a historical perspective of pricing, a discussion of current pricing structures, and insight into the future of pricing from three different perspectives: a database producer (Disclosure, Inc.), an online services provider (Questel-Orbit, Inc.), and a commercial online service/consumer…

  6. Providing Access to Electronic Information Resources in Further Education

    ERIC Educational Resources Information Center

    Banwell, Linda; Ray, Kathryn; Coulson, Graham; Urquhart, Christine; Lonsdale, Ray; Armstrong, Chris; Thomas, Rhian; Spink, Sin; Yeoman, Alison; Fenton, Roger; Rowley, Jennifer

    2004-01-01

    This article aims to provide a baseline for future studies on the provision and support for the use of digital or electronic information services (EIS) in further education. The analysis presented is based on a multi-level model of access, which encompasses access to and availability of information and communication technology (ICT) resources,…

  7. Think Locally: A Prudent Approach to Electronic Resource Management Systems

    ERIC Educational Resources Information Center

    Gustafson-Sundell, Nat

    2011-01-01

    A few articles have drawn some amount of attention specifically to the local causes of the success or failure of electronic resource management system (ERMS) implementations. In fact, it seems clear that local conditions will largely determine whether any given ERMS implementation will succeed or fail. This statement might seem obvious, but the…

  8. Electronic Resources: Access and Usage at Ashesi University College

    ERIC Educational Resources Information Center

    Dadzie, Perpetua S.

    2005-01-01

    Purpose: Sets out to investigate the use of electronic resources by students and faculty of Ashesi University, Ghana, in order to determine the level of use, the type of information accessed and the effectiveness of the library's communication tools for information research. Design/methodology/approach: A questionnaire-based survey was utilized.…

  9. Functional Complexity in Soft Electronic Matter

    SciTech Connect

    Bishop, Alan

    2006-08-04

    A substantial change is presently taking place in experimental and theoretical approaches to large classes of "strongly correlated" materials. The change reflects growing evidence that multiscale complexity (in space and time) is frequently both intrinsic and functional, and further, that intimate relationships between hierarchies of functional scales consitute essential "Systems" or "Networks." This complexity provides qualitatively new avenues for predictive design of technological materaisl, including instrically nanoscale structures. In the search for underpinning concepts and principles, the prevalence of local constraints and coexisting short- and long-range forces have become apparent as keys to some major class of materaisl with emergent "landscapes" of spatio-temporal patterns and associated glassy dynamics and statistics. This talk reviews our recent work in these directions in the context of elastically-driven textures in (a) directionally-bonded electronic materials, including superonducting, magnetoresistant, and ferroelectric oxides; and (b) bubble opening patterns in DNA. Underscored is the importance of suites of experimental probes being applied to establish the networks of functional scales: microscopic to mesoscopic to macroscopic. Recent advances in angle-resolved photoemission and inelastic neutron scattering experimental techniques are particularly valuable in this regard.

  10. Evaluating the appropriateness of electronic information resources for learning

    PubMed Central

    Nolan, Nathanial S.

    2016-01-01

    Objectives Current US medical students have begun to rely on electronic information repositories—such as UpToDate, AccessMedicine, and Wikipedia—for their pre-clerkship medical education. However, it is unclear whether these resources are appropriate for this level of learning due to factors involving information quality, level of evidence, and the requisite knowledgebase. This study evaluated appropriateness of electronic information resources from a novel perspective: amount of mental effort learners invest in interactions with these resources and effects of the experienced mental effort on learning. Methods Eighteen first-year medical students read about three unstudied diseases in the above-mentioned resources (a total of fifty-four observations). Their eye movement characteristics (i.e., fixation duration, fixation count, visit duration, and task-evoked pupillary response) were recorded and used as psychophysiological indicators of the experienced mental effort. Post reading, students' learning was assessed with multiple-choice tests. Eye metrics and test results constituted quantitative data analyzed according to the repeated Latin square design. Students' perceptions of interacting with the information resources were also collected. Participants' feedback during semi-structured interviews constituted qualitative data and was reviewed, transcribed, and open coded for emergent themes. Results Compared to AccessMedicine and Wikipedia, UpToDate was associated with significantly higher values of eye metrics, suggesting learners experienced higher mental effort. No statistically significant difference between the amount of mental effort and learning outcomes was found. More so, descriptive statistical analysis of the knowledge test scores suggested similar levels of learning regardless of the information resource used. Conclusions Judging by the learning outcomes, all three information resources were found appropriate for learning. UpToDate, however, when used

  11. Electronic Structure and Bonding in Complex Biomolecule

    NASA Astrophysics Data System (ADS)

    Ouyang, Lizhi

    2005-03-01

    For over a century vitamin B12 and its enzyme cofactor derivates have persistently attracted research efforts for their vital biological role, unique Co-C bonding, rich red-ox chemistry, and recently their candidacies as drug delivery vehicles etc. However, our understanding of this complex metalorganic molecule's efficient enzyme activated catalytic power is still controversial. We have for the first time calculated the electronic structure, Mulliken effective charge and bonding of a whole Vitamin B12 molecule without any structural simplification by first- principles approaches based on density functional theory using structures determined by high resolution X-ray diffraction. A partial density of states analysis shows excellent agreement with X-ray absorption data and has been used successfully to interpret measured optical absorption spectra. Mulliken bonding analysis of B12 and its derivatives reveal noticeable correlations between the two axial ligands which could be exploited by the enzyme to control the catalytic process. Our calculated X-ray near edge structure of B12 and its derivates using Slater's transition state theory are also in good agreement with experiments. The same approach has been applied to other B12 derivatives, ferrocene peptides, and recently DNA molecules.

  12. E-Resources Management: How We Positioned Our Organization to Implement an Electronic Resources Management System

    ERIC Educational Resources Information Center

    White, Marilyn; Sanders, Susan

    2009-01-01

    The Information Services Division (ISD) of the National Institute of Standards and Technology (NIST) positioned itself to successfully implement an electronic resources management system. This article highlights the ISD's unique ability to "team" across the organization to realize a common goal, develop leadership qualities in support of…

  13. E-Resources Management: How We Positioned Our Organization to Implement an Electronic Resources Management System

    ERIC Educational Resources Information Center

    White, Marilyn; Sanders, Susan

    2009-01-01

    The Information Services Division (ISD) of the National Institute of Standards and Technology (NIST) positioned itself to successfully implement an electronic resources management system. This article highlights the ISD's unique ability to "team" across the organization to realize a common goal, develop leadership qualities in support of…

  14. How students combine resources to build understanding of complex topics

    NASA Astrophysics Data System (ADS)

    Richards, Alan J.

    The field of Physics Education Research (PER) seeks to investigate how students learn physics and how instructors can help students learn more effectively. The process by which learners create understanding about a complex physics concept is an active area of research. My study explores this process, using solar cells as the context. To understand how a photovoltaic cell works involves drawing knowledge from many different areas of physics, so this provides a fertile area to study how students build understanding of complex ideas. I have used the "knowledge in pieces" theoretical framework to understand how students learn about solar cells by activating cognitive resources. In this framework, we can see learners building understanding out of more basic bits of knowledge, known as resources, that are derived from students' prior experience. This study seeks to learn more about how students combine multiple resources as they construct understanding of a complex physics topic. To achieve this goal, I have created instructional materials and assessment instruments used to collect written and spoken data on students' reasoning. The analysis of this data revealed that students are most likely to successfully build understanding when they activate multiple types of resource simultaneously. I propose possible explanations for this pattern and present ways this finding could impact instruction.

  15. Model complexity versus ensemble size: allocating resources for climate prediction.

    PubMed

    Ferro, Christopher A T; Jupp, Tim E; Lambert, F Hugo; Huntingford, Chris; Cox, Peter M

    2012-03-13

    A perennial question in modern weather forecasting and climate prediction is whether to invest resources in more complex numerical models or in larger ensembles of simulations. If this question is to be addressed quantitatively, then information is needed about how changes in model complexity and ensemble size will affect predictive performance. Information about the effects of ensemble size is often available, but information about the effects of model complexity is much rarer. An illustration is provided of the sort of analysis that might be conducted for the simplified case in which model complexity is judged in terms of grid resolution and ensemble members are constructed only by perturbing their initial conditions. The effects of resolution and ensemble size on the performance of climate simulations are described with a simple mathematical model, which is then used to define an optimal allocation of computational resources for a range of hypothetical prediction problems. The optimal resolution and ensemble size both increase with available resources, but their respective rates of increase depend on the values of two parameters that can be determined from a small number of simulations. The potential for such analyses to guide future investment decisions in climate prediction is discussed.

  16. A Complex Systems Model Approach to Quantified Mineral Resource Appraisal

    USGS Publications Warehouse

    Gettings, M.E.; Bultman, M.W.; Fisher, F.S.

    2004-01-01

    For federal and state land management agencies, mineral resource appraisal has evolved from value-based to outcome-based procedures wherein the consequences of resource development are compared with those of other management options. Complex systems modeling is proposed as a general framework in which to build models that can evaluate outcomes. Three frequently used methods of mineral resource appraisal (subjective probabilistic estimates, weights of evidence modeling, and fuzzy logic modeling) are discussed to obtain insight into methods of incorporating complexity into mineral resource appraisal models. Fuzzy logic and weights of evidence are most easily utilized in complex systems models. A fundamental product of new appraisals is the production of reusable, accessible databases and methodologies so that appraisals can easily be repeated with new or refined data. The data are representations of complex systems and must be so regarded if all of their information content is to be utilized. The proposed generalized model framework is applicable to mineral assessment and other geoscience problems. We begin with a (fuzzy) cognitive map using (+1,0,-1) values for the links and evaluate the map for various scenarios to obtain a ranking of the importance of various links. Fieldwork and modeling studies identify important links and help identify unanticipated links. Next, the links are given membership functions in accordance with the data. Finally, processes are associated with the links; ideally, the controlling physical and chemical events and equations are found for each link. After calibration and testing, this complex systems model is used for predictions under various scenarios.

  17. Analysis of empty responses from electronic resources in infobutton managers

    PubMed Central

    Long, Jie; Hulse, Nathan C.; Tao, Cui

    2015-01-01

    Infobuttons provide context-aware educational materials to both providers and patients and are becoming an important element in modern electronic health records (EHR) and patient health records (PHR). However, the content from different electronic resources (e-resource) as responses from infobutton manager has not been fully analyzed and evaluated. In this paper, we propose a method for automatically analyzing responses from infobutton manager. A tool is implemented to retrieve and analyze responses from infobutton manager. To test the tool, we extracted and sampled common and uncommon concepts from EHR usage data in Intermountain Healthcare’s enterprise data warehouse. From the output of the tool, we evaluate infobutton performance by multiple categories, including against the most and less common used concepts, grouped by different modules in patient portal, by different e-resources, and by type of access (standardized Health Level Seven (HL7) vs not). Based on the results of our evaluation, we provide suggestions for further enhancements of infobuttons to the current implementation, including suggesting accessing priorities of e-resources and encouraging the use of the HL7 standard. PMID:26958221

  18. Dockground: A comprehensive data resource for modeling of protein complexes.

    PubMed

    Kundrotas, Petras J; Anishchenko, Ivan; Dauzhenka, Taras; Kotthoff, Ian; Mnevets, Daniil; Copeland, Matthew M; Vakser, Ilya A

    2017-09-10

    Characterization of life processes at the molecular level requires structural details of protein interactions. The number of experimentally determined structures of protein-protein complexes accounts only for a fraction of known protein interactions. This gap in structural description of the interactome has to be bridged by modeling. An essential part of the development of structural modeling/docking techniques for protein interactions is databases of protein-protein complexes. They are necessary for studying protein interfaces, providing a knowledge base for docking algorithms, developing intermolecular potentials, search procedures, and scoring functions. Development of protein-protein docking techniques requires thorough benchmarking of different parts of the docking protocols on carefully curated sets of protein-protein complexes. We present a comprehensive description of the Dockground resource (http://dockground.compbio.ku.edu) for structural modeling of protein interactions, including previously unpublished unbound docking benchmark set 4, and the X-ray docking decoy set 2. The resource offers a variety of interconnected datasets of protein-protein complexes and other data for the development and testing of different aspects of protein docking methodologies. Based on protein-protein complexes extracted from the PDB biounit files, Dockground offers sets of X-ray unbound, simulated unbound, model, and docking decoy structures. All datasets are freely available for download, as a whole or selecting specific structures, through a user-friendly interface on one integrated website. This article is protected by copyright. All rights reserved. © 2017 The Protein Society.

  19. Electronic Resources Evaluation Central: Using Off-the-Shelf Software, Web 2.0 Tools, and LibGuides to Manage an Electronic Resources Evaluation Process

    ERIC Educational Resources Information Center

    England, Lenore; Fu, Li

    2011-01-01

    A critical part of electronic resources management, the electronic resources evaluation process is multi-faceted and includes a seemingly endless range of resources and tools involving numerous library staff. A solution is to build a Web site to bring all of the components together that can be implemented quickly and result in an organizational…

  20. Electronic Resources Evaluation Central: Using Off-the-Shelf Software, Web 2.0 Tools, and LibGuides to Manage an Electronic Resources Evaluation Process

    ERIC Educational Resources Information Center

    England, Lenore; Fu, Li

    2011-01-01

    A critical part of electronic resources management, the electronic resources evaluation process is multi-faceted and includes a seemingly endless range of resources and tools involving numerous library staff. A solution is to build a Web site to bring all of the components together that can be implemented quickly and result in an organizational…

  1. Journals, Data and Abstracts Make an Integrated Electronic Resource

    NASA Astrophysics Data System (ADS)

    Boyce, P.

    1996-12-01

    Astronomy now has an integrated, Web-based information resource for research papers, data and bibliographic information. The major scholarly research journals, a comprehensive abstract service and the astronomical data centers are now linked together to provide an information resource which is not available to most other scientific disciplines. As of January, 1997, the Astrophysical Journal joins the ApJ Letters on the Web. Astronomy and Astrophysics Supplements now has a page image version. Elsevier's electronic journal New Astronomy has recently made its appearance. Over forty percent of the new peer-reviewed, astronomical literature is now available electronically. The main Astronomy and Astrophysics journal, the Astronomical Journal and others will be available by 1998, at which point ninety percent of the literature will be available electronically, a figure not approached by any other scientific discipline. With so many different sources, one of the challenges has been to integrate the on-line, peer-reviewed literature into a resource which serves the astronomical community in a unified and coherent manner. Following the lead of the AAS, the major publishers have chosen to rely upon the NASA-supported Astrophysics Data System (ADS) and the astronomical data centers to provide the means by which the various separate journals can interoperate. The data centers and the ADS have developed unique identification codes for journal articles. By adopting the existing standard "bibcodes" and integrating them into their WWW links, each of the major astronomical journals are able to link to the abstracts of most of the referenced articles. Since the ADS also serves as an on-line repository for page images of the past twenty years of the major astronomical journals, the full text of many of the referenced articles are available, too. The articles in the ADS have recently been linked through their references, both forward and backward in time. With the "bibcode" providing

  2. Analysis of Human Resources Management Strategy in China Electronic Commerce Enterprises

    NASA Astrophysics Data System (ADS)

    Shao, Fang

    The paper discussed electronic-commerce's influence on enterprise human resources management, proposed and proved the human resources management strategy which electronic commerce enterprise should adopt from recruitment strategy to training strategy, keeping talent strategy and other ways.

  3. Evaluating increased resource use in fibromyalgia using electronic health records.

    PubMed

    Margolis, Jay M; Masters, Elizabeth T; Cappelleri, Joseph C; Smith, David M; Faulkner, Steven

    2016-01-01

    The management of fibromyalgia (FM), a chronic musculoskeletal disease, remains challenging, and patients with FM are often characterized by high health care resource utilization. This study sought to explore potential drivers of all-cause health care resource utilization and other factors associated with high resource use, using a large electronic health records (EHR) database to explore data from patients diagnosed with FM. This was a retrospective analysis of de-identified EHR data from the Humedica database. Adults (≥18 years) with FM were identified based on ≥2 International Classification of Diseases, Ninth Revision codes for FM (729.1) ≥30 days apart between January 1, 2008 and December 31, 2012 and were required to have evidence of ≥12 months continuous care pre- and post-index; first FM diagnosis was the index event; 12-month pre- and post-index reporting periods. Multivariable analysis evaluated relationships between variables and resource utilization. Patients were predominantly female (81.4%), Caucasian (87.7%), with a mean (standard deviation) age of 54.4 (14.8) years. The highest health care resource utilization was observed for the categories of "medication orders" and "physician office visits," with 12-month post-index means of 21.2 (21.5) drug orders/patient and 15.1 (18.1) office visits/patient; the latter accounted for 73.3% of all health care visits. Opioids were the most common prescription medication, 44.3% of all patients. The chance of high resource use was significantly increased (P<0.001) 26% among African-Americans vs Caucasians and for patients with specific comorbid conditions ranging from 6% (musculoskeletal pain or depression/bipolar disorder) to 21% (congestive heart failure). Factors significantly associated with increased medications ordered included being female (P<0.001) and specific comorbid conditions (P<0.05). Physician office visits and pharmacotherapy orders were key drivers of all-cause health care utilization, with

  4. Evaluating increased resource use in fibromyalgia using electronic health records

    PubMed Central

    Margolis, Jay M; Masters, Elizabeth T; Cappelleri, Joseph C; Smith, David M; Faulkner, Steven

    2016-01-01

    Objective The management of fibromyalgia (FM), a chronic musculoskeletal disease, remains challenging, and patients with FM are often characterized by high health care resource utilization. This study sought to explore potential drivers of all-cause health care resource utilization and other factors associated with high resource use, using a large electronic health records (EHR) database to explore data from patients diagnosed with FM. Methods This was a retrospective analysis of de-identified EHR data from the Humedica database. Adults (≥18 years) with FM were identified based on ≥2 International Classification of Diseases, Ninth Revision codes for FM (729.1) ≥30 days apart between January 1, 2008 and December 31, 2012 and were required to have evidence of ≥12 months continuous care pre- and post-index; first FM diagnosis was the index event; 12-month pre- and post-index reporting periods. Multivariable analysis evaluated relationships between variables and resource utilization. Results Patients were predominantly female (81.4%), Caucasian (87.7%), with a mean (standard deviation) age of 54.4 (14.8) years. The highest health care resource utilization was observed for the categories of “medication orders” and “physician office visits,” with 12-month post-index means of 21.2 (21.5) drug orders/patient and 15.1 (18.1) office visits/patient; the latter accounted for 73.3% of all health care visits. Opioids were the most common prescription medication, 44.3% of all patients. The chance of high resource use was significantly increased (P<0.001) 26% among African-Americans vs Caucasians and for patients with specific comorbid conditions ranging from 6% (musculoskeletal pain or depression/bipolar disorder) to 21% (congestive heart failure). Factors significantly associated with increased medications ordered included being female (P<0.001) and specific comorbid conditions (P<0.05). Conclusion Physician office visits and pharmacotherapy orders were key

  5. Complex wet-environments in electronic-structure calculations

    NASA Astrophysics Data System (ADS)

    Fisicaro, Giuseppe; Genovese, Luigi; Andreussi, Oliviero; Marzari, Nicola; Goedecker, Stefan

    The computational study of chemical reactions in complex, wet environments is critical for applications in many fields. It is often essential to study chemical reactions in the presence of an applied electrochemical potentials, including complex electrostatic screening coming from the solvent. In the present work we present a solver to handle both the Generalized Poisson and the Poisson-Boltzmann equation. A preconditioned conjugate gradient (PCG) method has been implemented for the Generalized Poisson and the linear regime of the Poisson-Boltzmann, allowing to solve iteratively the minimization problem with some ten iterations. On the other hand, a self-consistent procedure enables us to solve the Poisson-Boltzmann problem. The algorithms take advantage of a preconditioning procedure based on the BigDFT Poisson solver for the standard Poisson equation. They exhibit very high accuracy and parallel efficiency, and allow different boundary conditions, including surfaces. The solver has been integrated into the BigDFT and Quantum-ESPRESSO electronic-structure packages and it will be released as a independent program, suitable for integration in other codes. We present test calculations for large proteins to demonstrate efficiency and performances. This work was done within the PASC and NCCR MARVEL projects. Computer resources were provided by the Swiss National Supercomputing Centre (CSCS) under Project ID s499. LG acknowledges also support from the EXTMOS EU project.

  6. Evolution of complexity in a resource-based model

    NASA Astrophysics Data System (ADS)

    Fernández, Lenin; Campos, Paulo R. A.

    2017-02-01

    Through a resource-based modelling the evolution of organismal complexity is studied. In the model, the cells are characterized by their metabolic rates which, together with the availability of resource, determine the rate at which they divide. The population is structured in groups. Groups are also autonomous entities regarding reproduction and propagation, and so they correspond to a higher biological organization level. The model assumes reproductive altruism as there exists a fitness transfer from the cell level to the group level. Reproductive altruism comes about by inflicting a higher energetic cost to cells belonging to larger groups. On the other hand, larger groups are less prone to extinction. The strength of this benefit arising from group augmentation can be tuned by the synergistic parameter γ. Through extensive computer simulations we make a thorough exploration of the parameter space to find out the domain in which the formation of larger groups is allowed. We show that formation of small groups can be obtained for a low level of synergy. Larger group sizes can only be attained as synergistic interactions surpass a given level of strength. Although the total resource influx rate plays a key role in determining the number of groups coexisting at the equilibrium, its function on driving group size is minor. On the other hand, how the resource is seized by the groups matters.

  7. Electronic Resources and Mission Creep: Reorganizing the Library for the Twenty-First Century

    ERIC Educational Resources Information Center

    Stachokas, George

    2009-01-01

    The position of electronic resources librarian was created to serve as a specialist in the negotiation of license agreements for electronic resources, but mission creep has added more functions to the routine work of electronic resources such as cataloging, gathering information for collection development, and technical support. As electronic…

  8. Effects of Electronic Information Resources Skills Training for Lecturers on Pedagogical Practices and Research Productivity

    ERIC Educational Resources Information Center

    Bhukuvhani, Crispen; Chiparausha, Blessing; Zuvalinyenga, Dorcas

    2012-01-01

    Lecturers use various electronic resources at different frequencies. The university library's information literacy skills workshops and seminars are the main sources of knowledge of accessing electronic resources. The use of electronic resources can be said to have positively affected lecturers' pedagogical practices and their work in general. The…

  9. Electronic Resources and Mission Creep: Reorganizing the Library for the Twenty-First Century

    ERIC Educational Resources Information Center

    Stachokas, George

    2009-01-01

    The position of electronic resources librarian was created to serve as a specialist in the negotiation of license agreements for electronic resources, but mission creep has added more functions to the routine work of electronic resources such as cataloging, gathering information for collection development, and technical support. As electronic…

  10. Internal switches modulating electron tunneling currents in respiratory complex III.

    PubMed

    Hagras, Muhammad A; Stuchebrukhov, Alexei A

    2016-06-01

    In different X-ray crystal structures of bc1 complex, some of the key residues of electron tunneling pathways are observed in different conformations; here we examine their relative importance in modulating electron transfer and propose their possible gating function in the Q-cycle. The study includes inter-monomeric electron transfer; here we provide atomistic details of the reaction, and discuss the possible roles of inter-monomeric electronic communication in bc(1) complex. Binding of natural ligands or inhibitors leads to local conformational changes which propagate through protein and control the conformation of key residues involved in the electron tunneling pathways. Aromatic-aromatic interactions are highly utilized in the communication network since the key residues are aromatic in nature. The calculations show that there is a substantial change of the electron transfer rates between different redox pairs depending on the different conformations acquired by the key residues of the complex.

  11. Fingerprinting Electronic Molecular Complexes in Liquid

    NASA Astrophysics Data System (ADS)

    Nirmalraj, Peter; La Rosa, Andrea; Thompson, Damien; Sousa, Marilyne; Martin, Nazario; Gotsmann, Bernd; Riel, Heike

    2016-01-01

    Predicting the electronic framework of an organic molecule under practical conditions is essential if the molecules are to be wired in a realistic circuit. This demands a clear description of the molecular energy levels and dynamics as it adapts to the feedback from its evolving chemical environment and the surface topology. Here, we address this issue by monitoring in real-time the structural stability and intrinsic molecular resonance states of fullerene (C60)-based hybrid molecules in the presence of the solvent. Energetic levels of C60 hybrids are resolved by in situ scanning tunnelling spectroscopy with an energy resolution in the order of 0.1 eV at room-temperature. An ultra-thin organic spacer layer serves to limit contact metal-molecule energy overlap. The measured molecular conductance gap spread is statistically benchmarked against first principles electronic structure calculations and used to quantify the diversity in electronic species within a standard population of molecules. These findings provide important progress towards understanding conduction mechanisms at a single-molecular level and in serving as useful guidelines for rational design of robust nanoscale devices based on functional organic molecules.

  12. Fingerprinting Electronic Molecular Complexes in Liquid

    PubMed Central

    Nirmalraj, Peter; La Rosa, Andrea; Thompson, Damien; Sousa, Marilyne; Martin, Nazario; Gotsmann, Bernd; Riel, Heike

    2016-01-01

    Predicting the electronic framework of an organic molecule under practical conditions is essential if the molecules are to be wired in a realistic circuit. This demands a clear description of the molecular energy levels and dynamics as it adapts to the feedback from its evolving chemical environment and the surface topology. Here, we address this issue by monitoring in real-time the structural stability and intrinsic molecular resonance states of fullerene (C60)-based hybrid molecules in the presence of the solvent. Energetic levels of C60 hybrids are resolved by in situ scanning tunnelling spectroscopy with an energy resolution in the order of 0.1 eV at room-temperature. An ultra-thin organic spacer layer serves to limit contact metal-molecule energy overlap. The measured molecular conductance gap spread is statistically benchmarked against first principles electronic structure calculations and used to quantify the diversity in electronic species within a standard population of molecules. These findings provide important progress towards understanding conduction mechanisms at a single-molecular level and in serving as useful guidelines for rational design of robust nanoscale devices based on functional organic molecules. PMID:26743542

  13. Computational resources for cryo-electron tomography in Bsoft.

    PubMed

    Heymann, J Bernard; Cardone, Giovanni; Winkler, Dennis C; Steven, Alasdair C

    2008-03-01

    The Bsoft package [Heymann, J.B., Belnap, D.M., 2007. Bsoft: image processing and molecular modeling for electron microscopy. J. Struct. Biol. 157, 3-18] has been enhanced by adding utilities for processing electron tomographic (ET) data; in particular, cryo-ET data characterized by low contrast and high noise. To handle the high computational load efficiently, a workflow was developed, based on the database-like parameter handling in Bsoft, aimed at minimizing user interaction and facilitating automation. To the same end, scripting elements distribute the processing among multiple processors on the same or different computers. The resolution of a tomogram depends on the precision of projection alignment, which is usually based on pinpointing fiducial markers (electron-dense gold particles). Alignment requires accurate specification of the tilt axis, and our protocol includes a procedure for determining it to adequate accuracy. Refinement of projection alignment provides information that allows assessment of its precision, as well as projection quality control. We implemented a reciprocal space algorithm that affords an alternative to back-projection or real space algorithms for calculating tomograms. Resources are also included that allow resolution assessment by cross-validation (NLOO2D); denoising and interpretation; and the extraction, mutual alignment, and averaging of tomographic sub-volumes.

  14. Readability, complexity, and suitability analysis of online lymphedema resources.

    PubMed

    Tran, Bao Ngoc N; Singh, Mansher; Lee, Bernard T; Rudd, Rima; Singhal, Dhruv

    2017-06-01

    Over 72% of Americans use online health information to assist in health care decision-making. Previous studies of lymphedema literature have focused only on reading level of patient-oriented materials online. Findings indicate they are too advanced for most patients to comprehend. This, more comprehensive study, expands the previous analysis to include critical elements of health materials beyond readability using assessment tools to report on the complexity and density of data as well as text design, vocabulary, and organization. The top 10 highest ranked websites on lymphedema were identified using the most popular search engine (Google). Website content was analyzed for readability, complexity, and suitability using Simple Measure of Gobbledygook, PMOSE/iKIRSCH, and Suitability Assessment of Materials (SAM), respectively. PMOSE/iKIRSCH and SAM were performed by two independent raters. Fleiss' kappa score was calculated to ensure inter-rater reliability. Online lymphedema literature had a reading grade level of 14.0 (SMOG). Overall complexity score was 6.7 (PMOSE/iKIRSCH) corresponding to "low" complexity and requiring a 8th-12th grade education. Fleiss' kappa score was 80% (P = 0.04, "substantial" agreement). Overall suitability score was 45% (SAM) correlating to the lowest level of "adequate" suitability. Fleiss' kappa score was 76% (P = 0.06, "substantial" agreement). Online resources for lymphedema are above the recommended levels for readability and complexity. The suitability level is barely adequate for the intended audience. Overall, these materials are too sophisticated for the average American adult, whose literacy skills are well documented. Further efforts to revise these materials are needed to improve patient comprehension and understanding. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Geothermal resources and energy complex use in Russia

    NASA Astrophysics Data System (ADS)

    Svalova, V.

    2009-04-01

    Geothermal energy use is the perspective way to clean sustainable development of the world. Russia has rich high and low temperature geothermal resources and makes good steps in their use. In Russia the geothermal resources are used predominantly for heat supply both heating of several cities and settlements on Northern Caucasus and Kamchatka with a total number of the population 500000. Besides in some regions of country the deep heat is used for greenhouses of common area 465000 m2. Most active the hydrothermal resources are used in Krasnodar territory, Dagestan and on Kamchatka. The approximately half of extracted resources is applied for heat supply of habitation and industrial puttings, third - to a heating of greenhouses, and about 13 % - for industrial processes. Besides the thermal waters are used approximately on 150 health resorts and 40 factories on bottling mineral water. The most perspective direction of usage of low temperature geothermal resources is the use of heat pumps. This way is optimal for many regions of Russia - in its European part, on Ural and others. The electricity is generated by some geothermal power plants (GeoPP) only in the Kamchatka Peninsula and Kuril Islands. At present three stations work in Kamchatka: Pauzhetka GeoPP (11MW e installed capacity) and two Severo-Mutnovka GeoPP ( 12 and 50 MWe). Moreover, another GeoPP of 100 MVe is now under preparation in the same place. Two small GeoPP are in operation in Kuril's Kunashir Isl, and Iturup Isl, with installed capacity of 2,б MWe and 6 MWe respectively. There are two possible uses of geothermal resources depending on structure and properties of thermal waters: heat/power and mineral extraction. The heat/power direction is preferable for low mineralized waters when valuable components in industrial concentration are absent, and the general mineralization does not interfere with normal operation of system. When high potential geothermal waters are characterized by the high

  16. Assessing Ongoing Electronic Resource Purchases: Linking Tools to Synchronize Staff Workflows

    ERIC Educational Resources Information Center

    Carroll, Jeffrey D.; Major, Colleen; O'Neal, Nada; Tofanelli, John

    2012-01-01

    Ongoing electronic resource purchases represent a substantial proportion of collections budgets. Recognizing the necessity of systematic ongoing assessment with full selector engagement, Columbia University Libraries appointed an Electronic Resources Assessment Working Group to promote the inclusion of such resources within our current culture of…

  17. Assessing Ongoing Electronic Resource Purchases: Linking Tools to Synchronize Staff Workflows

    ERIC Educational Resources Information Center

    Carroll, Jeffrey D.; Major, Colleen; O'Neal, Nada; Tofanelli, John

    2012-01-01

    Ongoing electronic resource purchases represent a substantial proportion of collections budgets. Recognizing the necessity of systematic ongoing assessment with full selector engagement, Columbia University Libraries appointed an Electronic Resources Assessment Working Group to promote the inclusion of such resources within our current culture of…

  18. Quantum Calculations of Electron Tunneling in Respiratory Complex III.

    PubMed

    Hagras, Muhammad A; Hayashi, Tomoyuki; Stuchebrukhov, Alexei A

    2015-11-19

    The most detailed and comprehensive to date study of electron transfer reactions in the respiratory complex III of aerobic cells, also known as bc1 complex, is reported. In the framework of the tunneling current theory, electron tunneling rates and atomistic tunneling pathways between different redox centers were investigated for all electron transfer reactions comprising different stages of the proton-motive Q-cycle. The calculations reveal that complex III is a smart nanomachine, which under certain conditions undergoes conformational changes gating electron transfer, or channeling electrons to specific pathways. One-electron tunneling approximation was adopted in the tunneling calculations, which were performed using hybrid Broken-Symmetry (BS) unrestricted DFT/ZINDO levels of theory. The tunneling orbitals were determined using an exact biorthogonalization scheme that uniquely separates pairs of tunneling orbitals with small overlaps out of the remaining Franck-Condon orbitals with significant overlap. Electron transfer rates in different redox pairs show exponential distance dependence, in agreement with the reported experimental data; some reactions involve coupled proton transfer. Proper treatment of a concerted two-electron bifurcated tunneling reaction at the Q(o) site is given.

  19. Quantum Electron Tunneling in Respiratory Complex I1

    PubMed Central

    Hayashi, Tomoyuki; Stuchebrukhov, Alexei A.

    2014-01-01

    We have simulated the atomistic details of electronic wiring of all Fe/S clusters in complex I, a key enzyme in the respiratory electron transport chain. The tunneling current theory of many-electron systems is applied to the broken-symmetry (BS) states of the protein at the ZINDO level. One-electron tunneling approximation is found to hold in electron tunneling between the anti-ferromagnetic binuclear and tetranuclear Fe/S clusters with moderate induced polarization of the core electrons. Calculated tunneling energy is about 3 eV higher than Fermi level in the band gap of the protein, which supports that the mechanism of electron transfer is quantum mechanical tunneling, as in the rest of electron transport chain. Resulting electron tunneling pathways consist of up to three key contributing protein residues between neighboring Fe/S clusters. A distinct signature of the wave properties of electrons is observed as quantum interferences when multiple tunneling pathways exist. In N6a-N6b, electron tunnels along different pathways depending on the involved BS states, suggesting possible fluctuations of the tunneling pathways driven by the local protein environment. The calculated distance dependence of the electron transfer rates with internal water molecules included are in good agreement with a reported phenomenological relation. PMID:21495666

  20. Electronic Safety Resource Tools -- Supporting Hydrogen and Fuel Cell Commercialization

    SciTech Connect

    Barilo, Nick F.

    2014-09-29

    The Pacific Northwest National Laboratory (PNNL) Hydrogen Safety Program conducted a planning session in Los Angeles, CA on April 1, 2014 to consider what electronic safety tools would benefit the next phase of hydrogen and fuel cell commercialization. A diverse, 20-person team led by an experienced facilitator considered the question as it applied to the eight most relevant user groups. The results and subsequent evaluation activities revealed several possible resource tools that could greatly benefit users. The tool identified as having the greatest potential for impact is a hydrogen safety portal, which can be the central location for integrating and disseminating safety information (including most of the tools identified in this report). Such a tool can provide credible and reliable information from a trustworthy source. Other impactful tools identified include a codes and standards wizard to guide users through a series of questions relating to application and specific features of the requirements; a scenario-based virtual reality training for first responders; peer networking tools to bring users from focused groups together to discuss and collaborate on hydrogen safety issues; and a focused tool for training inspectors. Table ES.1 provides results of the planning session, including proposed new tools and changes to existing tools.

  1. Controlling user access to electronic resources without password

    DOEpatents

    Smith, Fred Hewitt

    2015-06-16

    Described herein are devices and techniques for remotely controlling user access to a restricted computer resource. The process includes pre-determining an association of the restricted computer resource and computer-resource-proximal environmental information. Indicia of user-proximal environmental information are received from a user requesting access to the restricted computer resource. Received indicia of user-proximal environmental information are compared to associated computer-resource-proximal environmental information. User access to the restricted computer resource is selectively granted responsive to a favorable comparison in which the user-proximal environmental information is sufficiently similar to the computer-resource proximal environmental information. In at least some embodiments, the process further includes comparing user-supplied biometric measure and comparing it with a predetermined association of at least one biometric measure of an authorized user. Access to the restricted computer resource is granted in response to a favorable comparison.

  2. Solving complex and disordered surface structures with electron diffraction

    SciTech Connect

    Van Hove, M.A.

    1987-10-01

    The past of surface structure determination with low-energy electron diffraction (LEED) will be briefly reviewed, setting the stage for a discussion of recent and future developments. The aim of these developments is to solve complex and disordered surface structures. Some efficient solutions to the theoretical and experimental problems will be presented. Since the theoretical problems dominate, the emphasis will be on theoretical approaches to the calculation of the multiple scattering of electrons through complex and disordered surfaces. 49 refs., 13 figs., 1 tab.

  3. Electronic Resource Management 2.0: Using Web 2.0 Technologies as Cost-Effective Alternatives to an Electronic Resource Management System

    ERIC Educational Resources Information Center

    Murray, Adam

    2008-01-01

    Designed to assist with the management of e-resources, electronic resource management (ERM) systems are time- and fund-consuming to purchase and maintain. Questions of system compatibility, data population, and workflow design/redesign can be difficult to answer; sometimes those answers are not what we'd prefer to hear. The two primary functions…

  4. Electronic Resource Management 2.0: Using Web 2.0 Technologies as Cost-Effective Alternatives to an Electronic Resource Management System

    ERIC Educational Resources Information Center

    Murray, Adam

    2008-01-01

    Designed to assist with the management of e-resources, electronic resource management (ERM) systems are time- and fund-consuming to purchase and maintain. Questions of system compatibility, data population, and workflow design/redesign can be difficult to answer; sometimes those answers are not what we'd prefer to hear. The two primary functions…

  5. Synthesis, electronic, photoacoustic and electron spin resonance investigations on some tetrathiocyanate binuclear mixed-metal complexes

    NASA Astrophysics Data System (ADS)

    Singh, Raghuvir

    Complexes of the type M 1M 2(SCN) 4xL[M 1 = Ni(II); M 2 = Cd(II) and Hg(II) and L = pyridine, morpholine, dioxan, benzo(f)quinoline, 2,2'-bipyridine, 2,2'-bipyridine N, N'-dioxide, isonicotinic acid hydrazide and 1,10-phenanthroline: x = 2 or 4] have been synthesized and characterized by chemical analysis, magnetic susceptibility, infrared, electronic and photoacoustic (PAS) spectra as well as electron spin resonance (ESR) spectral studies in the solid and solution state. The different coordination sites have been investigated in these ligands towards metal coordination and the behaviour of thiocyanate anions studied. Electron spin resonance spectral data for copper complexes show the distorted octahedral stereochemistry around copper(II) in these complexes. The parameters such as g∥, g⊥, A∥, A⊥, < g>, < A> and α 2 calculated for the copper complexes from their ESR spectra indicate the presence of unpaired electron in d x2- y2 or d z2 orbitals. The photoacoustic and electronic spectra of these complexes were studied in the solid state to see the nature of thiocyanate and overall symmetry of the complexes. The results on electronic and photoacoustic spectral studies are in good agreement with ESR data.

  6. Structural complexities in the active layers of organic electronics.

    PubMed

    Lee, Stephanie S; Loo, Yueh-Lin

    2010-01-01

    The field of organic electronics has progressed rapidly in recent years. However, understanding the direct structure-function relationships between the morphology in electrically active layers and the performance of devices composed of these materials has proven difficult. The morphology of active layers in organic electronics is inherently complex, with heterogeneities existing across multiple length scales, from subnanometer to micron and millimeter range. A major challenge still facing the organic electronics community is understanding how the morphology across all of the length scales in active layers collectively determines the device performance of organic electronics. In this review we highlight experiments that have contributed to the elucidation of structure-function relationships in organic electronics and also point to areas in which knowledge of such relationships is still lacking. Such knowledge will lead to the ability to select active materials on the basis of their inherent properties for the fabrication of devices with prespecified characteristics.

  7. Resources

    MedlinePlus

    ... Gastrointestinal disorders - resources Hearing impairment - resources Hearing or speech impairment - resources Heart disease - resources Hemophilia - resources Herpes - resources Incest - resources Incontinence - ...

  8. Quantum simulations of small electron-hole complexes

    SciTech Connect

    Lee, M.A.; Kalia, R.K.; Vashishta, P.D.

    1984-09-01

    The Green's Function Monte Carlo method is applied to the calculation of the binding energies of electron-hole complexes in semiconductors. The quantum simulation method allows the unambiguous determination of the ground state energy and the effects of band anisotropy on the binding energy. 22 refs., 1 fig.

  9. One-Stop Shopping: Presenting Disparate Electronic Resources through a Single Interface.

    ERIC Educational Resources Information Center

    Briden, Judi; Reeb, Brenda; Zhang, Allison

    The Electronic Resources Team at the University of Rochester (New York) River Campus Libraries pursued the concept of one-stop shopping as a component of their new integrated library system Voyager, which debuted in January 1997. Faced with a growing variety of electronic resources with no single guide to their existence and access, the Team dealt…

  10. Developing Humanities Collections in the Digital Age: Exploring Humanities Faculty Engagement with Electronic and Print Resources

    ERIC Educational Resources Information Center

    Kachaluba, Sarah Buck; Brady, Jessica Evans; Critten, Jessica

    2014-01-01

    This article is based on quantitative and qualitative research examining humanities scholars' understandings of the advantages and disadvantages of print versus electronic information resources. It explores how humanities' faculty members at Florida State University (FSU) use print and electronic resources, as well as how they perceive these…

  11. Developing Humanities Collections in the Digital Age: Exploring Humanities Faculty Engagement with Electronic and Print Resources

    ERIC Educational Resources Information Center

    Kachaluba, Sarah Buck; Brady, Jessica Evans; Critten, Jessica

    2014-01-01

    This article is based on quantitative and qualitative research examining humanities scholars' understandings of the advantages and disadvantages of print versus electronic information resources. It explores how humanities' faculty members at Florida State University (FSU) use print and electronic resources, as well as how they perceive these…

  12. The Relevancy of Graduate Curriculum to Human Resource Professionals' Electronic Communication.

    ERIC Educational Resources Information Center

    Hoell, Robert C.; Henry, Gordon O.

    2003-01-01

    Electronic communications of human resource professionals and the content of 23 university human resource management courses were categorized using the Human Resource Certification Institute's body of knowledge. Differences between proportion of topics discussed and topics covered in curricula suggest some topics are over- or undertaught.…

  13. Strategic Planning for Electronic Resources Management: A Case Study at Gustavus Adolphus College

    ERIC Educational Resources Information Center

    Hulseberg, Anna; Monson, Sarah

    2009-01-01

    Electronic resources, the tools we use to manage them, and the needs and expectations of our users are constantly evolving; at the same time, the roles, responsibilities, and workflow of the library staff who manage e-resources are also in flux. Recognizing a need to be more intentional and proactive about how we manage e-resources, the…

  14. Use and Users of Electronic Library Resources: An Overview and Analysis of Recent Research Studies

    ERIC Educational Resources Information Center

    Tenopir, Carol

    2003-01-01

    This Council on Library and Information Resources (CLIR) report summarizes and analyzes more than 200 recent research publications that focus on the use of electronic library resources (digital libraries and digital resources) and were published between 1995 and 2003. Eight major ongoing studies (each with multiple publications) are identified as…

  15. Strategic Planning for Electronic Resources Management: A Case Study at Gustavus Adolphus College

    ERIC Educational Resources Information Center

    Hulseberg, Anna; Monson, Sarah

    2009-01-01

    Electronic resources, the tools we use to manage them, and the needs and expectations of our users are constantly evolving; at the same time, the roles, responsibilities, and workflow of the library staff who manage e-resources are also in flux. Recognizing a need to be more intentional and proactive about how we manage e-resources, the…

  16. Electron localization in a mixed-valence diniobium benzene complex

    DOE PAGES

    Gianetti, Thomas L.; Nocton, Grégory; Minasian, Stefan G.; ...

    2014-11-11

    Reaction of the neutral diniobium benzene complex {[Nb(BDI)NtBu]2(μ-C6H6)} (BDI = N,N'-diisopropylbenzene-β-diketiminate) with Ag[B(C6F5)4] results in a single electron oxidation to produce a cationic diniobium arene complex, {[Nb(BDI)NtBu]2(μ-C6H6)}{B(C6F5)4}. Investigation of the solid state and solution phase structure using single-crystal X-ray diffraction, cyclic voltammetry, magnetic susceptibility, and multinuclear NMR spectroscopy indicates that the oxidation results in an asymmetric molecule with two chemically inequivalent Nb atoms. Further characterization using density functional theory (DFT) calculations, UV-visible, Nb L3,2-edge X-ray absorption near-edge structure (XANES), and EPR spectroscopies supports assignment of a diniobium complex, in which one Nb atom carries a single unpaired electron that ismore » not largely delocalized on the second Nb atom. During the oxidative transformation, one electron is removed from the δ-bonding HOMO, which causes a destabilization of the molecule and formation of an asymmetric product. Subsequent reactivity studies indicate that the oxidized product allows access to metal-based chemistry with substrates that did not exhibit reactivity with the starting neutral complex.« less

  17. Electron localization in a mixed-valence diniobium benzene complex

    SciTech Connect

    Gianetti, Thomas L.; Nocton, Grégory; Minasian, Stefan G.; Kaltsoyannis, Nikolas; Kilcoyne, A. L. David; Kozimor, Stosh A.; Shuh, David K.; Tyliszczak, Tolek; Bergman, Robert G.; Arnold, John

    2014-11-11

    Reaction of the neutral diniobium benzene complex {[Nb(BDI)NtBu]2(μ-C6H6)} (BDI = N,N'-diisopropylbenzene-β-diketiminate) with Ag[B(C6F5)4] results in a single electron oxidation to produce a cationic diniobium arene complex, {[Nb(BDI)NtBu]2(μ-C6H6)}{B(C6F5)4}. Investigation of the solid state and solution phase structure using single-crystal X-ray diffraction, cyclic voltammetry, magnetic susceptibility, and multinuclear NMR spectroscopy indicates that the oxidation results in an asymmetric molecule with two chemically inequivalent Nb atoms. Further characterization using density functional theory (DFT) calculations, UV-visible, Nb L3,2-edge X-ray absorption near-edge structure (XANES), and EPR spectroscopies supports assignment of a diniobium complex, in which one Nb atom carries a single unpaired electron that is not largely delocalized on the second Nb atom. During the oxidative transformation, one electron is removed from the δ-bonding HOMO, which causes a destabilization of the molecule and formation of an asymmetric product. Subsequent reactivity studies indicate that the oxidized product allows access to metal-based chemistry with substrates that did not exhibit reactivity with the starting neutral complex.

  18. The electronic spectra of mu-peroxodicobalt(III) complexes

    NASA Technical Reports Server (NTRS)

    Miskowski, Vincent M.

    1987-01-01

    Problems found in the determination of the electronic spectra of mu-peroxodicobalt(III) complexes are considered, and the common formation of different mu-peroxocomplexes upon oxygenation of Co(II)-ligand solutions is discussed. Three classes of spectra have been identified: (1) planar single bridged complexes; (2) nonplanar single-bridged complexes with a dihedral angle near 145 deg; and (3) dibridged mu-OH(-),O2(2-) complexes with a dihedral angle near 60 deg. All of the peroxide ligand-to-metal charge-transfer spectra are found to be consistent with a simple model that assumes a sinusoidal dependence of pi-asterisk O2(2-) energies and sigma-overlaps upon the dihedral angle.

  19. Reducing Clinical Trial Monitoring Resource Allocation and Costs Through Remote Access to Electronic Medical Records

    PubMed Central

    Uren, Shannon C.; Kirkman, Mitchell B.; Dalton, Brad S.; Zalcberg, John R.

    2013-01-01

    Purpose: With electronic medical records (eMRs), the option now exists for clinical trial monitors to perform source data verification (SDV) remotely. We report on a feasibility study of remote access to eMRs for SDV and the potential advantages of such a process in terms of resource allocation and cost. Methods: The Clinical Trials Unit at the Peter MacCallum Cancer Centre, in collaboration with Novartis Pharmaceuticals Australia, conducted a 6-month feasibility study of remote SDV. A Novartis monitor was granted dedicated software and restricted remote access to the eMR portal of the cancer center, thereby providing an avenue through which perform SDV. Results: Six monitoring visits were conducted during the study period, four of which were performed remotely. The ability to conduct two thirds of the monitoring visits remotely in this complex phase III study resulted in an overall cost saving to Novartis. Similarly, remote monitoring eased the strain on internal resources, particularly monitoring space and hospital computer terminal access, at the cancer center. Conclusion: Remote access to patient eMRs for SDV is feasible and is potentially an avenue through which resources can be more efficiently used. Although this feasibility study involved limited numbers, there is no limit to scaling these processes to any number of patients enrolled onto large clinical trials. PMID:23633977

  20. Glycan complexity dictates microbial resource allocation in the large intestine

    USDA-ARS?s Scientific Manuscript database

    The structure of the human gut microbiota, which impacts on the health of the host, is controlled by complex dietary carbohydrates and members of the Bacteroidetes phylum are the major contributors to the degradation of complex dietary carbohydrates. The extent to which complex dietary carbohydrates...

  1. Nursing resource considerations for implementing an electronic documentation system.

    PubMed

    Saletnik, Laurie Ann; Niedlinger, Margaret K; Wilson, Marisa

    2008-03-01

    Implementation of an or management information system (ORMIS) requires a significant commitment of human resources. The experiences of the personnel at The Johns Hopkins Hospital, Baltimore, MD, as they transitioned to using a single, unified, computerized ORMIS are detailed in this article. Included are discussions of the nursing resources involved in the process, the lessons learned, and the work that remains to be completed for the hospital to fully utilize the system.

  2. Paper versus electronic documentation in complex chronic illness: a comparison.

    PubMed

    Smith, Catherine Arnott; Haque, Saira N

    2006-01-01

    This paper reports an analysis and comparison of the electronic and paper medical records of 5 clinically complex persons with spina bifida, who were seen as in- and outpatients at a small Northeastern urban hospital. The combination of chronic illness, multiple medical and allied health specialties, and longer lifespan in this population ensures both a quantitative volume and qualitative complexity of medical event documentation. This ensures a rich field for research into the content and the nature of the fragmented data presently locked in the paper record.

  3. Light induced electron transfer reactions of metal complexes

    SciTech Connect

    Sutin, N; Creutz, C

    1980-01-01

    Properties of the excited states of tris(2,2'-bipyridine) and tris(1,10-phenanthroline) complexes of chromium(III), iron(II), ruthenium(II), osmium(II), rhodium(III), and iridium(III) are described. The electron transfer reactions of the ground and excited states are discussed and interpreted in terms of the driving force for the reaction and the distortions of the excited states relative to the corresponding ground states. General considerations relevant to the conversion of light into chemical energy are presented and progress in the use of polypyridine complexes to effect the light decomposition of water into hydrogen and oxygen is reviewed.

  4. Medical resident choices of electronic drug information resources.

    PubMed

    Hughes, Gregory J; Patel, Priti; Mason, Christopher

    2015-06-01

    To determine medical residents' day-to-day use of drug information resources since their choices of these resources, when faced with common questions, are unknown. An online survey including simulated drug information questions was administered to 146 medical residents in the Department of General Internal Medicine during July 2012. Residents were given a wide range of choices in drug information resources to answer these questions and were instructed to select what they would choose in actual practice. A score was assigned to each resource corresponding to a "best," "intermediate," or "not good" choice. Seventy-three respondents completed the survey and results were analyzed for statistical significance. Fifty-seven percent of respondents reported receiving no formal training regarding drug information. Statistical analyses revealed there were no significant differences in performance based on postgraduate year (P = .43) or extent of prior training (P = .45). Individual question responses revealed a generally infrequent selection of "best" choices. Less than 10% of the respondents chose the "best" answer for drug information questions related to drug interactions, herbal supplements, adverse events, and medication identification. Further training in drug information resource selection is warranted in the medical residency program to increase the frequency of use of higher quality resources. © The Author(s) 2014.

  5. Remote Electronic Resources and the OPAC: Illustrated by the Unisa Library Experience.

    ERIC Educational Resources Information Center

    Van der Merwe, Ina; Van Eeden, Welna; Hartzer, Sandra

    This paper describes the Unisa (University of South Africa) Library's experience with cataloging remote electronic resources, including electronic journals, electronic text files, online databases, digital images, Unisa campus Web sites, and mailing list discussions. The first section discusses the decision to add bibliographic references for…

  6. Electronic Spectra of Bare and Solvated Ruthenium Polypyridine Complexes

    NASA Astrophysics Data System (ADS)

    Xu, Shuang; Smith, James E. T.; Weber, J. Mathias

    2016-06-01

    We present work on a prototypical water oxidation catalyst, namely the aqua-complex [(bpy)(tpy)Ru-OH_2]2+ (2,2'-bpy = bipyridine, tpy = 2,2':6',2"-terpyridine), and its hydrated clusters [(bpy)(tpy)Ru-OH_2]2+ ·(H2O)_n, with n = 1 - 4. This complex is the starting species in a catalytic cycle for water oxidation. We couple electrospray ionization mass spectrometry with laser spectroscopy to circumvent challenges that arise in reactive solutions from speciation. Here, we report the electronic spectrum of [(bpy)(tpy)Ru-OH_2]2+ by photodissociation spectroscopy of mass selected, cryogenically prepared ions, and we examine effects of its microhydration environment on its electronic structure. In particular, we investigate the solvatochromic shift of the spectral envelope upon sequential addition of water molecules up to the tetrahydrate.

  7. Geometric and electronic structures of potassium-adsorbed rubrene complexes

    SciTech Connect

    Li, Tsung-Lung; Lu, Wen-Cai

    2015-06-28

    The geometric and electronic structures of potassium-adsorbed rubrene complexes are studied in this article. It is found that the potassium-rubrene (K{sub 1}RUB) complexes inherit the main symmetry characteristics from their pristine counterparts and are thus classified into D{sub 2}- and C{sub 2h}-like complexes according to the relative orientations of the four phenyl side groups. The geometric structures of K{sub 1}RUB are governed by two general effects on the total energy: Deformation of the carbon frame of the pristine rubrene increases the total energy, while proximity of the potassium ion to the phenyl ligands decreases the energy. Under these general rules, the structures of D{sub 2}- and C{sub 2h}-like K{sub 1}RUB, however, exhibit their respective peculiarities. These peculiarities can be illustrated by their energy profiles of equilibrium structures. For the potassium adsorption-sites, the D{sub 2}-like complexes show minimum-energy basins, whereas the C{sub 2h}-like ones have single-point minimum-energies. If the potassium atom ever has the energy to diffuse from the minimum-energy site, the potassium diffusion path on the D{sub 2}-like complexes is most likely along the backbone in contrast to the C{sub 2h}-like ones. Although the electronic structures of the minimum-energy structures of D{sub 2}- and C{sub 2h}-like K{sub 1}RUB are very alike, decompositions of their total spectra reveal insights into the electronic structures. First, the spectral shapes are mainly determined by the facts that, in comparison with the backbone carbons, the phenyl carbons have more uniform chemical environments and far less contributions to the electronic structures around the valence-band edge. Second, the electron dissociated from the potassium atom mainly remains on the backbone and has little effects on the electronic structures of the phenyl groups. Third, the two phenyls on the same side of the backbone as the potassium atom have more similar chemical environments

  8. [HYGIENIC REGULATION OF THE USE OF ELECTRONIC EDUCATIONAL RESOURCES IN THE MODERN SCHOOL].

    PubMed

    Stepanova, M I; Aleksandrova, I E; Sazanyuk, Z I; Voronova, B Z; Lashneva, L P; Shumkova, T V; Berezina, N O

    2015-01-01

    We studied the effect of academic studies with the use a notebook computer and interactive whiteboard on the functional state of an organism of schoolchildren. Using a complex of hygienic and physiological methods of the study we established that regulation of the computer activity of students must take into account not only duration but its intensity either. Design features of a notebook computer were shown both to impede keeping the optimal working posture in primary school children and increase the risk offormation of disorders of vision and musculoskeletal system. There were established the activating influence of the interactive whiteboard on performance activities and favorable dynamics of indices of the functional state of the organism of students under keeping optimal density of the academic study and the duration of its use. There are determined safety regulations of the work of schoolchildren with electronic resources in the educational process.

  9. Perspective: Explicitly correlated electronic structure theory for complex systems

    NASA Astrophysics Data System (ADS)

    Grüneis, Andreas; Hirata, So; Ohnishi, Yu-ya; Ten-no, Seiichiro

    2017-02-01

    The explicitly correlated approach is one of the most important breakthroughs in ab initio electronic structure theory, providing arguably the most compact, accurate, and efficient ansatz for describing the correlated motion of electrons. Since Hylleraas first used an explicitly correlated wave function for the He atom in 1929, numerous attempts have been made to tackle the significant challenges involved in constructing practical explicitly correlated methods that are applicable to larger systems. These include identifying suitable mathematical forms of a correlated wave function and an efficient evaluation of many-electron integrals. R12 theory, which employs the resolution of the identity approximation, emerged in 1985, followed by the introduction of novel correlation factors and wave function ansätze, leading to the establishment of F12 theory in the 2000s. Rapid progress in recent years has significantly extended the application range of explicitly correlated theory, offering the potential of an accurate wave-function treatment of complex systems such as photosystems and semiconductors. This perspective surveys explicitly correlated electronic structure theory, with an emphasis on recent stochastic and deterministic approaches that hold significant promise for applications to large and complex systems including solids.

  10. Controlling user access to electronic resources without password

    DOEpatents

    Smith, Fred Hewitt

    2017-08-22

    Described herein are devices and techniques for remotely controlling user access to a restricted computer resource. The process includes obtaining an image from a communication device of a user. An individual and a landmark are identified within the image. Determinations are made that the individual is the user and that the landmark is a predetermined landmark. Access to a restricted computing resource is granted based on the determining that the individual is the user and that the landmark is the predetermined landmark. Other embodiments are disclosed.

  11. Preservation of and Permanent Access to Electronic Information Resources

    DTIC Science & Technology

    2004-12-01

    up in this attitude as well. Electronic information includes a variety of object types such as electronic journals, e-books, databases , data sets...firewalls, require passwords to access, are hidden within Web-accessible databases , or require payment. The major lesson from efforts to develop selection...pages or those that are created out of a database , portal system, or content management system. The American Astronomical Society (AAS) has perhaps

  12. Glycan complexity dictates microbial resource allocation in the large intestine

    PubMed Central

    Rogowski, Artur; Briggs, Jonathon A.; Mortimer, Jennifer C.; Tryfona, Theodora; Terrapon, Nicolas; Lowe, Elisabeth C.; Baslé, Arnaud; Morland, Carl; Day, Alison M.; Zheng, Hongjun; Rogers, Theresa E.; Thompson, Paul; Hawkins, Alastair R.; Yadav, Madhav P.; Henrissat, Bernard; Martens, Eric C.; Dupree, Paul; Gilbert, Harry J.; Bolam, David N.

    2015-01-01

    The structure of the human gut microbiota is controlled primarily through the degradation of complex dietary carbohydrates, but the extent to which carbohydrate breakdown products are shared between members of the microbiota is unclear. We show here, using xylan as a model, that sharing the breakdown products of complex carbohydrates by key members of the microbiota, such as Bacteroides ovatus, is dependent on the complexity of the target glycan. Characterization of the extensive xylan degrading apparatus expressed by B. ovatus reveals that the breakdown of the polysaccharide by the human gut microbiota is significantly more complex than previous models suggested, which were based on the deconstruction of xylans containing limited monosaccharide side chains. Our report presents a highly complex and dynamic xylan degrading apparatus that is fine-tuned to recognize the different forms of the polysaccharide presented to the human gut microbiota. PMID:26112186

  13. Building an Integrated User Interface to Electronic Resources.

    ERIC Educational Resources Information Center

    Caswell, Jerry V.

    1997-01-01

    Client/server computing and the adoption of the World Wide Web make it possible for academic libraries to build automated library systems that present locally mounted and remote resources through a common interface. This article recounts issues encountered by the Iowa State University Library as it undertook this process. (Author/LRW)

  14. Interactive Printouts Integrating Multilingual Multimedia and Sign Language Electronic Resources

    ERIC Educational Resources Information Center

    Kanev, Kamen; Barneva, Reneta P.; Brimkov, Valentin E.; Kaneva, Dimitrina

    2010-01-01

    In this article we outline our previous implementations of multilingual multimedia dictionaries and discuss possibilities for adding new functionalities and expanding their coverage. Independently developed sign language dictionary resources are further explored and considered for inclusion in an integrated multilingual multimedia dictionary with…

  15. Interactive Printouts Integrating Multilingual Multimedia and Sign Language Electronic Resources

    ERIC Educational Resources Information Center

    Kanev, Kamen; Barneva, Reneta P.; Brimkov, Valentin E.; Kaneva, Dimitrina

    2010-01-01

    In this article we outline our previous implementations of multilingual multimedia dictionaries and discuss possibilities for adding new functionalities and expanding their coverage. Independently developed sign language dictionary resources are further explored and considered for inclusion in an integrated multilingual multimedia dictionary with…

  16. Iterative resource allocation for ranking spreaders in complex networks

    NASA Astrophysics Data System (ADS)

    Ren, Zhuo-Ming; Zeng, An; Chen, Duan-Bing; Liao, Hao; Liu, Jian-Guo

    2014-05-01

    Ranking the spreading influence of nodes in networks is a very important issue with wide applications in many different fields. Various topology-based centrality measures have been proposed to identify influential spreaders. However, the spreading influence of a node is usually not only determined by its own centrality but also largely influenced by the centrality of neighbors. To incorporate the centrality information of neighbors in ranking spreaders, we design an iterative resource allocation (IRA) process in which the resource of nodes distributes to their neighbors according to neighbors' centrality. After iterations, the resource amount on each node will be stable and the final resources of nodes are used to rank their spreading influence. The iterative process can be applied to many traditional centrality measures including degree, K-shell, closeness, and betweenness. The validation of our method is based on the susceptible-infected-recovered (SIR) spreading in four representative real datasets. The results show that the ranking accuracy of the traditional centrality measures is remarkably enhanced by IRA.

  17. Cryo-electron tomography of microtubule-kinesin motor complexes.

    PubMed

    Cope, Julia; Gilbert, Susan; Rayment, Ivan; Mastronarde, David; Hoenger, Andreas

    2010-05-01

    Microtubules complexed with molecular motors of the kinesin family or non-motor microtubule associated proteins (MAPs) such as tau or EB1 have been the subject of cryo-electron microcopy based 3-D studies for several years. Most of these studies that targeted complexes with intact microtubules have been carried out by helical 3-D reconstruction, while few were analyzed by single particle approaches or from 2-D crystalline arrays. Helical reconstruction of microtubule-MAP or motor complexes has been extremely successful but by definition, all helical 3-D reconstruction attempts require perfectly helical assemblies, which presents a serious limitation and confines the attempts to 15- or 16-protofilament microtubules, microtubule configurations that are very rare in nature. The rise of cryo-electron tomography within the last few years has now opened a new avenue towards solving 3-D structures of microtubule-MAP complexes that do not form helical assemblies, most importantly for the subject here, all microtubules that exhibit a lattice seam. In addition, not all motor domains or MAPs decorate the microtubule surface regularly enough to match the underlying microtubule lattice, or they adopt conformations that deviate from helical symmetry. Here we demonstrate the power and limitation of cryo-electron tomography using two kinesin motor domains, the monomeric Eg5 motor domain, and the heterodimeric Kar3Vik1 motor. We show here that tomography does not exclude the possibility of post-tomographic averaging when identical sub-volumes can be extracted from tomograms and in both cases we were able to reconstruct 3-D maps of conformations that are not possible to obtain using helical or other averaging-based methods. Copyright 2009 Elsevier Inc. All rights reserved.

  18. On Convergence of Development Costs and Cost Models for Complex Spaceflight Instrument Electronics

    NASA Technical Reports Server (NTRS)

    Kizhner, Semion; Patel, Umeshkumar D.; Kasa, Robert L.; Hestnes, Phyllis; Brown, Tammy; Vootukuru, Madhavi

    2008-01-01

    Development costs of a few recent spaceflight instrument electrical and electronics subsystems have diverged from respective heritage cost model predictions. The cost models used are Grass Roots, Price-H and Parametric Model. These cost models originated in the military and industry around 1970 and were successfully adopted and patched by NASA on a mission-by-mission basis for years. However, the complexity of new instruments recently changed rapidly by orders of magnitude. This is most obvious in the complexity of representative spaceflight instrument electronics' data system. It is now required to perform intermediate processing of digitized data apart from conventional processing of science phenomenon signals from multiple detectors. This involves on-board instrument formatting of computational operands from row data for example, images), multi-million operations per second on large volumes of data in reconfigurable hardware (in addition to processing on a general purpose imbedded or standalone instrument flight computer), as well as making decisions for on-board system adaptation and resource reconfiguration. The instrument data system is now tasked to perform more functions, such as forming packets and instrument-level data compression of more than one data stream, which are traditionally performed by the spacecraft command and data handling system. It is furthermore required that the electronics box for new complex instruments is developed for one-digit watt power consumption, small size and that it is light-weight, and delivers super-computing capabilities. The conflict between the actual development cost of newer complex instruments and its electronics components' heritage cost model predictions seems to be irreconcilable. This conflict and an approach to its resolution are addressed in this paper by determining the complexity parameters, complexity index, and their use in enhanced cost model.

  19. Developing integrated methods to address complex resource and environmental issues

    USGS Publications Warehouse

    Smith, Kathleen S.; Phillips, Jeffrey D.; McCafferty, Anne E.; Clark, Roger N.

    2016-02-08

    IntroductionThis circular provides an overview of selected activities that were conducted within the U.S. Geological Survey (USGS) Integrated Methods Development Project, an interdisciplinary project designed to develop new tools and conduct innovative research requiring integration of geologic, geophysical, geochemical, and remote-sensing expertise. The project was supported by the USGS Mineral Resources Program, and its products and acquired capabilities have broad applications to missions throughout the USGS and beyond.In addressing challenges associated with understanding the location, quantity, and quality of mineral resources, and in investigating the potential environmental consequences of resource development, a number of field and laboratory capabilities and interpretative methodologies evolved from the project that have applications to traditional resource studies as well as to studies related to ecosystem health, human health, disaster and hazard assessment, and planetary science. New or improved tools and research findings developed within the project have been applied to other projects and activities. Specifically, geophysical equipment and techniques have been applied to a variety of traditional and nontraditional mineral- and energy-resource studies, military applications, environmental investigations, and applied research activities that involve climate change, mapping techniques, and monitoring capabilities. Diverse applied geochemistry activities provide a process-level understanding of the mobility, chemical speciation, and bioavailability of elements, particularly metals and metalloids, in a variety of environmental settings. Imaging spectroscopy capabilities maintained and developed within the project have been applied to traditional resource studies as well as to studies related to ecosystem health, human health, disaster assessment, and planetary science. Brief descriptions of capabilities and laboratory facilities and summaries of some

  20. Stability of sulfate complexes of electronically excited uranyl

    SciTech Connect

    Ostakhov, S.S.; Kazakov, V.P.; Afonichev, D.D.

    1995-11-01

    The complex formation of electronically excited uranyl ions with SO{sub 4}{sup 2-}anions in 0.1 M aqueous HClO{sub 4} has been studied by time-resolved luminescence spectroscopy. The stability constants of uranyl sulfate complexes (UO{sub 2}SO{sub 4}) (K=870 1 mol{sup -1}) and [UO{sub 2}(SO{sub 4}){sub 2}{sup 2-}](K=47000 1 mol{sup -1}) in excited state have been determined; they are more than an order of magnitude greater than those reported for complex formation of uranyl ions in the ground state. The complex formation of uranyl with sulfate ions is accompanied by the increase of the quantum yield of the uranyl lumenescence. The maxima of luminescence and absorption bands of uranyl ions are shifted with increasing the total concentration of SO{sub 4}{sup 2-} in solution, which supports the data obtained. The shift of the maxima of luminescence bands is observed at a sulfate concentration that is considerably lower than that causing the same shift of the maxima of the absorption bands. Such effect is consistent with the calculated stability constants of sulfate complexes of excited uranyl ions.

  1. Complex formation dynamics in a single-molecule electronic device

    PubMed Central

    Wen, Huimin; Li, Wengang; Chen, Jiewei; He, Gen; Li, Longhua; Olson, Mark A.; Sue, Andrew C.-H.; Stoddart, J. Fraser; Guo, Xuefeng

    2016-01-01

    Single-molecule electronic devices offer unique opportunities to investigate the properties of individual molecules that are not accessible in conventional ensemble experiments. However, these investigations remain challenging because they require (i) highly precise device fabrication to incorporate single molecules and (ii) sufficient time resolution to be able to make fast molecular dynamic measurements. We demonstrate a graphene-molecule single-molecule junction that is capable of probing the thermodynamic and kinetic parameters of a host-guest complex. By covalently integrating a conjugated molecular wire with a pendent crown ether into graphene point contacts, we can transduce the physical [2]pseudorotaxane (de)formation processes between the electron-rich crown ether and a dicationic guest into real-time electrical signals. The conductance of the single-molecule junction reveals two-level fluctuations that are highly dependent on temperature and solvent environments, affording a nondestructive means of quantitatively determining the binding and rate constants, as well as the activation energies, for host-guest complexes. The thermodynamic processes reveal the host-guest binding to be enthalpy-driven and are consistent with conventional 1H nuclear magnetic resonance titration experiments. This electronic device opens up a new route to developing single-molecule dynamics investigations with microsecond resolution for a broad range of chemical and biochemical applications. PMID:28138528

  2. Using Electron Distributions to Probe Energy Surfaces at Complex R

    NASA Astrophysics Data System (ADS)

    Macek, J. H.; Ovchinnikov, S. Yu.

    1997-04-01

    The hidden crossing theory describes ion-atom collisions(S. Yu. Ovchinnikov and E. A. Solovév, Comments At. Mol. Phys. 22) 69 (1988). in terms of a single function \\varepsilon(R) defined for all complex R, where R is the distance between target and projectile nuclei. Conventional adiabatic energy curves \\varepsilon_n(R) represent different branches of \\varepsilon(R) at real, positive R. Electron distributions are computed by evaluating a phase integral along an appropriate path in the complex R-plane. The real part of the phase oscillates rapidly for a class of transitions that proceed via the "top of barrier" mechanism. Electron distributions oscillate owing to interfrence between σ and π transitions, and this oscillation relates closely to the real part of \\varepsilon(R) for complex R. The oscillation rate is in qualitative agreement with measurements (R. Döner, K. Khemliche, M. H. Prior, C. L. Cocke, J. A. Gary, R. E. Olson, V. Mergel, J. Ullrich and H. Schmidt-Böking, Phys. Rev. Lett.77), 1024 (1996).

  3. Managing Selection for Electronic Resources: Kent State University Develops a New System to Automate Selection

    ERIC Educational Resources Information Center

    Downey, Kay

    2012-01-01

    Kent State University has developed a centralized system that manages the communication and work related to the review and selection of commercially available electronic resources. It is an automated system that tracks the review process, provides selectors with price and trial information, and compiles reviewers' feedback about the resource. It…

  4. A Study on Developing Evaluation Criteria for Electronic Resources in Evaluation Indicators of Libraries

    ERIC Educational Resources Information Center

    Noh, Younghee

    2010-01-01

    This study aimed to improve the current state of electronic resource evaluation in libraries. While the use of Web DB, e-book, e-journal, and other e-resources such as CD-ROM, DVD, and micro materials is increasing in libraries, their use is not comprehensively factored into the general evaluation of libraries and may diminish the reliability of…

  5. Managing Selection for Electronic Resources: Kent State University Develops a New System to Automate Selection

    ERIC Educational Resources Information Center

    Downey, Kay

    2012-01-01

    Kent State University has developed a centralized system that manages the communication and work related to the review and selection of commercially available electronic resources. It is an automated system that tracks the review process, provides selectors with price and trial information, and compiles reviewers' feedback about the resource. It…

  6. A Study on Developing Evaluation Criteria for Electronic Resources in Evaluation Indicators of Libraries

    ERIC Educational Resources Information Center

    Noh, Younghee

    2010-01-01

    This study aimed to improve the current state of electronic resource evaluation in libraries. While the use of Web DB, e-book, e-journal, and other e-resources such as CD-ROM, DVD, and micro materials is increasing in libraries, their use is not comprehensively factored into the general evaluation of libraries and may diminish the reliability of…

  7. Video Killed the Radio Star: Language Students' Use of Electronic Resources-Reading or Viewing?

    ERIC Educational Resources Information Center

    Kiliçkaya, Ferit

    2016-01-01

    The current study aimed to investigate language students' use of print and electronic resources for their research papers required in research techniques class, focusing on which reading strategies they used while reading these resources. The participants of the study were 90 sophomore students enrolled in the research techniques class offered at…

  8. An Evaluation of Electronic Product Design Education Using Hypermedia-Resourced Learning Environments

    ERIC Educational Resources Information Center

    Page, Tom; Thorsteinsson, Gisli

    2006-01-01

    The work outlined here provides a comprehensive report and formative observations of the development and implementation of hypermedia resources for learning and teaching used in conjunction with a managed learning environment (MLE). These resources are used to enhance teaching and learning of an electronics module in product design at final year…

  9. Electronic Resources and the Education of History Professionals

    ERIC Educational Resources Information Center

    Mulligan, William H., Jr.

    2001-01-01

    The transforming effects of the tremendous advances in technology that have reshaped the economy and many other elements of American society have had an equally profound impact on historical agencies. The personal computer, the Internet, and associated electronic communications developments have already transformed the museum and historical agency…

  10. Structural and Electronic Investigations of Complex Intermetallic Compounds

    SciTech Connect

    Ko, Hyunjin

    2008-01-01

    In solid state chemistry, numerous investigations have been attempted to address the relationships between chemical structure and physical properties. Such questions include: (1) How can we understand the driving forces of the atomic arrangements in complex solids that exhibit interesting chemical and physical properties? (2) How do different elements distribute themselves in a solid-state structure? (3) Can we develop a chemical understanding to predict the effects of valence electron concentration on the structures and magnetic ordering of systems by both experimental and theoretical means? Although these issues are relevant to various compound classes, intermetallic compounds are especially interesting and well suited for a joint experimental and theoretical effort. For intermetallic compounds, the questions listed above are difficult to answer since many of the constituent atoms simply do not crystallize in the same manner as in their separate, elemental structures. Also, theoretical studies suggest that the energy differences between various structural alternatives are small. For example, Al and Ga both belong in the same group on the Periodic Table of Elements and share many similar chemical properties. Al crystallizes in the fcc lattice with 4 atoms per unit cell and Ga crystallizes in an orthorhombic unit cell lattice with 8 atoms per unit cell, which are both fairly simple structures (Figure 1). However, when combined with Mn, which itself has a very complex cubic crystal structure with 58 atoms per unit cell, the resulting intermetallic compounds crystallize in a completely different fashion. At the 1:1 stoichiometry, MnAl forms a very simple tetragonal lattice with two atoms per primitive unit cell, while MnGa crystallizes in a complicated rhombohedral unit cell with 26 atoms within the primitive unit cell. The mechanisms influencing the arrangements of atoms in numerous crystal structures have been studied theoretically by calculating electronic

  11. The Tolman electronic parameter (TEP) and the metal-metal electronic communication in ditopic NHC complexes.

    PubMed

    Gusev, Dmitry G; Peris, Eduardo

    2013-05-28

    Whereas the electronic communication between metals in dimetallic organometallic compounds is often assessed through cyclic voltammetric measurements, we have found that the variations in the Tolman electronic parameter (TEP) can also be an alternative and effective way of determining this type of interaction. The TEP values of several (CO)3Ni-NHC-X systems with five different ditopic NHC ligand systems [triazolyldiylidene (A), bis(imidazolylidene) (B), benzobis(imidazolylidene) (C), cyclopenta[f,g]acenaphthylenebis(imidazolylidene) (D) and bis(imidazolidinylidene) (F)] were determined by means of DFT calculations. Based on these values, the electron-withdrawing character of the X metal fragments employed in this study was found to increase in the order IrCp(CO) → RhCl(COD) → Ni(CO)3 → Cr(CO)5 → RhCl(CO)2. We found that the degree of electronic interaction through the ditopic NHC ligands is the strongest in A, followed by B and F, while being weak in B and C. The TEP values and the quantitative analysis of the upper molecular orbitals of A and F and their (CO)3Ni-NHC-Ni(CO)3 complexes strongly suggest that the principal electronic interaction between the metal centres of the M-NHC-M' complexes is of σ-type, via the delocalized HOMO and HOMO - 1 orbitals of the NHC ligands.

  12. How Students Combine Resources to Build Understanding of Complex Topics

    ERIC Educational Resources Information Center

    Richards, Alan J.

    2013-01-01

    The field of Physics Education Research (PER) seeks to investigate how students learn physics and how instructors can help students learn more effectively. The process by which learners create understanding about a complex physics concept is an active area of research. My study explores this process, using solar cells as the context. To understand…

  13. How Students Combine Resources to Build Understanding of Complex Topics

    ERIC Educational Resources Information Center

    Richards, Alan J.

    2013-01-01

    The field of Physics Education Research (PER) seeks to investigate how students learn physics and how instructors can help students learn more effectively. The process by which learners create understanding about a complex physics concept is an active area of research. My study explores this process, using solar cells as the context. To understand…

  14. Radio Resource Allocation on Complex 4G Wireless Cellular Networks

    NASA Astrophysics Data System (ADS)

    Psannis, Kostas E.

    2015-09-01

    In this article we consider the heuristic algorithm which improves step by step wireless data delivery over LTE cellular networks by using the total transmit power with the constraint on users’ data rates, and the total throughput with the constraints on the total transmit power as well as users’ data rates, which are jointly integrated into a hybrid-layer design framework to perform radio resource allocation for multiple users, and to effectively decide the optimal system parameter such as modulation and coding scheme (MCS) in order to adapt to the varying channel quality. We propose new heuristic algorithm which balances the accessible data rate, the initial data rates of each user allocated by LTE scheduler, the priority indicator which signals delay- throughput- packet loss awareness of the user, and the buffer fullness by achieving maximization of radio resource allocation for multiple users. It is noted that the overall performance is improved with the increase in the number of users, due to multiuser diversity. Experimental results illustrate and validate the accuracy of the proposed methodology.

  15. Where Do Electronic Books Fit in the College Research Arsenal of Resources?

    ERIC Educational Resources Information Center

    Barbier, Patricia

    2007-01-01

    Student use of electronic books has become an accepted supplement to traditional resources. Student use and satisfaction was monitored through an online course discussion board. Increased use of electronic books indicate this service is an accepted supplement to the print book collection.

  16. Where Do Electronic Books Fit in the College Research Arsenal of Resources?

    ERIC Educational Resources Information Center

    Barbier, Patricia

    2007-01-01

    Student use of electronic books has become an accepted supplement to traditional resources. Student use and satisfaction was monitored through an online course discussion board. Increased use of electronic books indicate this service is an accepted supplement to the print book collection.

  17. Beyond Information Quality: Fitness for Purpose and Electronic Information Resource Use.

    ERIC Educational Resources Information Center

    Klobas, Jane E.

    1995-01-01

    Examines influences on the use of electronic information resources, including the Internet. Highlights include information quality and accessibility; the Technology Assessment Model; the Fitness for Purpose model; the Theory of Planned Behavior; and a study in Australia that compared the ability of these models to explain electronic information…

  18. Protein complexing in a methanogen suggests electron bifurcation and electron delivery from formate to heterodisulfide reductase

    PubMed Central

    Costa, Kyle C.; Wong, Phoebe M.; Wang, Tiansong; Lie, Thomas J.; Dodsworth, Jeremy A.; Swanson, Ingrid; Burn, June A.; Hackett, Murray; Leigh, John A.

    2010-01-01

    In methanogenic Archaea, the final step of methanogenesis generates methane and a heterodisulfide of coenzyme M and coenzyme B (CoM-S-S-CoB). Reduction of this heterodisulfide by heterodisulfide reductase to regenerate HS-CoM and HS-CoB is an exergonic process. Thauer et al. [Thauer, et al. 2008 Nat Rev Microbiol 6:579–591] recently suggested that in hydrogenotrophic methanogens the energy of heterodisulfide reduction powers the most endergonic reaction in the pathway, catalyzed by the formylmethanofuran dehydrogenase, via flavin-based electron bifurcation. Here we present evidence that these two steps in methanogenesis are physically linked. We identify a protein complex from the hydrogenotrophic methanogen, Methanococcus maripaludis, that contains heterodisulfide reductase, formylmethanofuran dehydrogenase, F420-nonreducing hydrogenase, and formate dehydrogenase. In addition to establishing a physical basis for the electron-bifurcation model of energy conservation, the composition of the complex also suggests that either H2 or formate (two alternative electron donors for methanogenesis) can donate electrons to the heterodisulfide-H2 via F420-nonreducing hydrogenase or formate via formate dehydrogenase. Electron flow from formate to the heterodisulfide rather than the use of H2 as an intermediate represents a previously unknown path of electron flow in methanogenesis. We further tested whether this path occurs by constructing a mutant lacking F420-nonreducing hydrogenase. The mutant displayed growth equal to wild-type with formate but markedly slower growth with hydrogen. The results support the model of electron bifurcation and suggest that formate, like H2, is closely integrated into the methanogenic pathway. PMID:20534465

  19. Progression in Complexity: Contextualizing Sustainable Marine Resources Management in a 10th Grade Classroom

    ERIC Educational Resources Information Center

    Bravo-Torija, Beatriz; Jimenez-Aleixandre, Maria-Pilar

    2012-01-01

    Sustainable management of marine resources raises great challenges. Working with this socio-scientific issue in the classroom requires students to apply complex models about energy flow and trophic pyramids in order to understand that food chains represent transfer of energy, to construct meanings for sustainable resources management through…

  20. Progression in Complexity: Contextualizing Sustainable Marine Resources Management in a 10th Grade Classroom

    ERIC Educational Resources Information Center

    Bravo-Torija, Beatriz; Jimenez-Aleixandre, Maria-Pilar

    2012-01-01

    Sustainable management of marine resources raises great challenges. Working with this socio-scientific issue in the classroom requires students to apply complex models about energy flow and trophic pyramids in order to understand that food chains represent transfer of energy, to construct meanings for sustainable resources management through…

  1. Potassium under pressure: Electronic origin of complex structures

    NASA Astrophysics Data System (ADS)

    Degtyareva, V. F.

    2014-10-01

    Recent high-pressure X-ray diffraction studies of alkali metals revealed unusual complex structures that follow the body-centred and face-centred cubic structures on compression. The structural sequence of potassium under compression to 1 Mbar is as follows: bcc-fcc-h-g (tI19*), hP4-oP8-tI4-oC16. We consider configurations of Brillouin-Jones zones and the Fermi surface within a nearly-free-electron model in order to analyze the importance of these configurations for the crystal structure stability. Formation of Brillouin zone planes close to the Fermi surface is related to opening an energy gap at these planes and reduction of crystal energy. Under pressure, this mechanism becomes more important leading to appearance of complex low-symmetry structures. The stability of the post-fcc phases in K is attributed to the changes in the valence electron configuration under strong compression.

  2. Preparation of macromolecular complexes for cryo-electron microscopy.

    PubMed

    Grassucci, Robert A; Taylor, Derek J; Frank, Joachim

    2007-01-01

    This protocol describes the preparation of frozen-hydrated single-particle specimens of macromolecular complexes. First, it describes how to create a grid surface coated with holey carbon by first inducing holes in a Formvar film to act as a template for the holey carbon that is stable under cryo-electron microscopy (cryo-EM) conditions and is sample-friendly. The protocol then describes the steps required to deposit the homogeneous sample on the grid and to plunge-freeze the grid into liquid ethane at the temperature of liquid nitrogen, so that it is suitable for cryo-EM visualization. It takes 4-5 h to make several hundred holey carbon grids and about 1 h to make the frozen-hydrated grids. The time required for sample purification varies from hours to days, depending on the sample and the specific procedure required. A companion protocol details how to collect cryo-EM data using an FEI Tecnai transmission electron microscope that can subsequently be processed to obtain a three-dimensional reconstruction of the macromolecular complex.

  3. Focused Research Group in Correlated Electron and Complex Materials

    SciTech Connect

    Wang, Ziqiang

    2016-02-17

    While the remarkable physical properties of correlated and complex electronic materials hold great promise for technological applications, one of the key values of the research in this field is its profound impact on fundamental physics. The transition metal oxides, pnictides, and chalcogenides play a key role and occupy an especially important place in this field. The basic reason is that the outer shell of transition metals contains the atomic d-orbitals that have small spatial extent, but not too small to behave as localized orbtials. These d-electrons therefore have a small wave function overlap in a solid, e.g. in an octahedral environment, and form energy bands that are relatively narrow and on the scale of the short-range intra-atomic Coulomb repulsion (Hubbard U). In this intermediate correlation regime lies the challenge of the many-body physics responsible for new and unconventional physical properties. The study of correlated electron and complex materials represents both the challenge and the vitality of condensed matter and materials physics and often demands close collaborations among theoretical and experimental groups with complementary techniques. Our team has a track record and a long-term research goal of studying the unusual complexities and emergent behaviors in the charge, spin, and orbital sectors of the transition metal compounds in order to gain basic knowledge of the quantum electronic states of matter. During the funding period of this grant, the team continued their close collaborations between theory, angle-resolved photoemission spectroscopy, and scanning tunneling microscopy and made significant progress and contributions to the field of iron-based superconductors, copper-oxide high-temperature superconductors, triangular lattice transition metal oxide cobaltates, strontium ruthenates, spin orbital coupled iridates, as well as topological insulators and other topological quantum states of matter. These results include both new

  4. Role of 4 f electrons in crystallographic and magnetic complexity

    NASA Astrophysics Data System (ADS)

    Pathak, Arjun K.; Paudyal, Durga; Mudryk, Yaroslav; Pecharsky, Vitalij K.

    2017-08-01

    The functionality of many magnetic materials critically depends on first manipulating and then taking advantage of highly nonlinear changes of properties that occur during phase transformations. Unique to lanthanides, property-defining 4 f electrons are highly localized and, as commonly accepted, play little to no role in chemical bonding. Yet here we demonstrate that the competition between 4 f -electron energy landscapes of Dy (4 f9 ) and Er (4 f11 ) is the key element of the puzzle required to explain complex interplay of magnetic and structural features observed in E r1 -xD yxC o2 , and likely many other mixed lanthanide systems. Unlike the parent binaries—DyC o2 and ErC o2 —E r1 -xD yxC o2 exhibits two successive magnetostructural transitions: a first order at TC, followed by a second order in the ferrimagnetically ordered state. Supported by first-principles calculations, our results offer new opportunities for targeted design of magnetic materials with multiple functionalities, and also provide a critical insight into the role of 4 f electrons in controlling the magnetism and structure of lanthanide intermetallics.

  5. Role of 4f electrons in crystallographic and magnetic complexity

    DOE PAGES

    Pathak, Arjun K.; Paudyal, Durga; Mudryk, Yaroslav; ...

    2017-08-09

    Here, the functionality of many magnetic materials critically depends on first manipulating and then taking advantage of highly nonlinear changes of properties that occur during phase transformations. Unique to lanthanides, property-defining 4f electrons are highly localized and, as commonly accepted, play little to no role in chemical bonding. Yet here we demonstrate that the competition between 4f-electron energy landscapes of Dy (4f9) and Er (4f11) is the key element of the puzzle required to explain complex interplay of magnetic and structural features observed in Er1–xDyxCo2, and likely many other mixed lanthanide systems. Unlike the parent binaries—DyCo2 and ErCo2—Er1–xDyxCo2 exhibits twomore » successive magnetostructural transitions: a first order at TC, followed by a second order in the ferrimagnetically ordered state. Supported by first-principles calculations, our results offer new opportunities for targeted design of magnetic materials with multiple functionalities, and also provide a critical insight into the role of 4f electrons in controlling the magnetism and structure of lanthanide intermetallics.« less

  6. Diameter dependent electron transfer kinetics in semiconductor-enzyme complexes.

    PubMed

    Brown, Katherine A; Song, Qing; Mulder, David W; King, Paul W

    2014-10-28

    Excited state electron transfer (ET) is a fundamental step for the catalytic conversion of solar energy into chemical energy. To understand the properties controlling ET between photoexcited nanoparticles and catalysts, the ET kinetics were measured for solution-phase complexes of CdTe quantum dots and Clostridium acetobutylicum [FeFe]-hydrogenase I (CaI) using time-resolved photoluminescence spectroscopy. Over a 2.0-3.5 nm diameter range of CdTe nanoparticles, the observed ET rate (kET) was sensitive to CaI concentration. To account for diameter effects on CaI binding, a Langmuir isotherm and two geometric binding models were created to estimate maximal CaI affinities and coverages at saturating concentrations. Normalizing the ET kinetics to CaI surface coverage for each CdTe diameter led to k(ET) values that were insensitive to diameter, despite a decrease in the free energy for photoexcited ET (ΔGET) with increasing diameter. The turnover frequency (TOF) of CaI in CdTe-CaI complexes was measured at several molar ratios. Normalization for diameter-dependent changes in CaI coverage showed an increase in TOF with diameter. These results suggest that k(ET) and H2 production for CdTe-CaI complexes are not strictly controlled by ΔG(ET) and that other factors must be considered.

  7. Adapting practice-based intervention research to electronic environments: opportunities and complexities at two institutions.

    PubMed

    Stille, Christopher J; Lockhart, Steven A; Maertens, Julie A; Madden, Christi A; Darden, Paul M

    2015-01-01

    Primary care practice-based research has become more complex with increased use of electronic health records (EHRs). Little has been reported about changes in study planning and execution that are required as practices change from paper-based to electronic-based environments. We describe the evolution of a pediatric practice-based intervention study as it was adapted for use in the electronic environment, to enable other practice-based researchers to plan efficient, effective studies. We adapted a paper-based pediatric office-level intervention to enhance parent-provider communication about subspecialty referrals for use in two practice-based research networks (PBRNs) with partially and fully electronic environments. We documented the process of adaptation and its effect on study feasibility and efficiency, resource use, and administrative and regulatory complexities, as the study was implemented in the two networks. Considerable time and money was required to adapt the paper-based study to the electronic environment, requiring extra meetings with institutional EHR-, regulatory-, and administrative teams, and increased practice training. Institutional unfamiliarity with using EHRs in practice-based research, and the consequent need to develop new policies, were major contributors to delays. Adapting intervention tools to the EHR and minimizing practice disruptions was challenging, but resulted in several efficiencies as compared with a paper-based project. In particular, recruitment and tracking of subjects and data collection were easier and more efficient. Practice-based intervention research in an electronic environment adds considerable cost and time at the outset of a study, especially for centers unfamiliar with such research. Efficiencies generated have the potential of easing the work of study enrollment, subject tracking, and data collection.

  8. Assurance of Complex Electronics. What Path Do We Take?

    NASA Technical Reports Server (NTRS)

    Plastow, Richard A.

    2007-01-01

    Many of the methods used to develop software bare a close resemblance to Complex Electronics (CE) development. CE are now programmed to perform tasks that were previously handled in software, such as communication protocols. For instance, Field Programmable Gate Arrays (FPGAs) can have over a million logic gates while system-on-chip (SOC) devices can combine a microprocessor, input and output channels, and sometimes an FPGA for programmability. With this increased intricacy, the possibility of "software-like" bugs such as incorrect design, logic, and unexpected interactions within the logic is great. Since CE devices are obscuring the hardware/software boundary, we propose that mature software methodologies may be utilized with slight modifications to develop these devices. By using standardized S/W Engineering methods such as checklists, missing requirements and "bugs" can be detected earlier in the development cycle, thus creating a development process for CE that will be easily maintained and configurable based on the device used.

  9. Controlling collective dynamics in complex minority-game resource-allocation systems.

    PubMed

    Zhang, Ji-Qiang; Huang, Zi-Gang; Dong, Jia-Qi; Huang, Liang; Lai, Ying-Cheng

    2013-05-01

    Resource allocation takes place in various kinds of real-world complex systems, such as traffic systems, social services institutions or organizations, or even ecosystems. The fundamental principle underlying complex resource-allocation dynamics is Boolean interactions associated with minority games, as resources are generally limited and agents tend to choose the least used resource based on available information. A common but harmful dynamical behavior in resource-allocation systems is herding, where there are time intervals during which a large majority of the agents compete for a few resources, leaving many other resources unused. Accompanying the herd behavior is thus strong fluctuations with time in the number of resources being used. In this paper, we articulate and establish that an intuitive control strategy, namely pinning control, is effective at harnessing the herding dynamics. In particular, by fixing the choices of resources for a few agents while leaving the majority of the agents free, herding can be eliminated completely. Our investigation is systematic in that we consider random and targeted pinning and a variety of network topologies, and we carry out a comprehensive analysis in the framework of mean-field theory to understand the working of control. The basic philosophy is then that, when a few agents waive their freedom to choose resources by receiving sufficient incentives, the majority of the agents benefit in that they will make fair, efficient, and effective use of the available resources. Our work represents a basic and general framework to address the fundamental issue of fluctuations in complex dynamical systems with significant applications to social, economical, and political systems.

  10. Controlling collective dynamics in complex minority-game resource-allocation systems

    NASA Astrophysics Data System (ADS)

    Zhang, Ji-Qiang; Huang, Zi-Gang; Dong, Jia-Qi; Huang, Liang; Lai, Ying-Cheng

    2013-05-01

    Resource allocation takes place in various kinds of real-world complex systems, such as traffic systems, social services institutions or organizations, or even ecosystems. The fundamental principle underlying complex resource-allocation dynamics is Boolean interactions associated with minority games, as resources are generally limited and agents tend to choose the least used resource based on available information. A common but harmful dynamical behavior in resource-allocation systems is herding, where there are time intervals during which a large majority of the agents compete for a few resources, leaving many other resources unused. Accompanying the herd behavior is thus strong fluctuations with time in the number of resources being used. In this paper, we articulate and establish that an intuitive control strategy, namely pinning control, is effective at harnessing the herding dynamics. In particular, by fixing the choices of resources for a few agents while leaving the majority of the agents free, herding can be eliminated completely. Our investigation is systematic in that we consider random and targeted pinning and a variety of network topologies, and we carry out a comprehensive analysis in the framework of mean-field theory to understand the working of control. The basic philosophy is then that, when a few agents waive their freedom to choose resources by receiving sufficient incentives, the majority of the agents benefit in that they will make fair, efficient, and effective use of the available resources. Our work represents a basic and general framework to address the fundamental issue of fluctuations in complex dynamical systems with significant applications to social, economical, and political systems.

  11. Electron transfer and catalysis with high-valent metal-oxo complexes.

    PubMed

    Fukuzumi, Shunichi

    2015-04-21

    High-valent metal-oxo complexes are produced by reductive activation of dioxygen via reduction of metal complexes with reductants and dioxygen. Photoinduced electron transfer from substrates to metal complexes with dioxygen also leads to the generation of high-valent metal-oxo complexes that can oxygenate substrates. In such a case metal complexes act as a photocatalyst to oxygenate substrates with dioxygen. High-valent metal-oxo complexes are also produced by proton-coupled electron-transfer oxidation of metal complexes by one-electron oxidants with water, oxygenating substrates to regenerate metal complexes. In such a case metal complexes act as a catalyst for electron-transfer oxygenation of substrates by one-electron oxidants with water that acts as an oxygen source. The one-electron oxidants which can oxidize metal complexes can be replaced by much weaker oxidants by a combination of redox photocatalysts and metal complexes. Thus, photocatalytic oxygenation of substrates proceeds via photoinduced electron transfer from a photocatalyst to reductants followed by proton-coupled electron transfer oxidation of metal complexes with the oxidized photocatalyst to produce high-valent metal-oxo complexes that oxygenate substrates. Thermal and photoinduced electron-transfer catalytic reactions of high-valent metal-oxo complexes for oxygenation of substrates using water or dioxygen as an oxygen source are summarized in this perspective.

  12. ATOMIC RESOLUTION CRYO ELECTRON MICROSCOPY OF MACROMOLECULAR COMPLEXES

    PubMed Central

    ZHOU, Z. HONG

    2013-01-01

    Single-particle cryo electron microscopy (cryoEM) is a technique for determining three-dimensional (3D) structures from projection images of molecular complexes preserved in their “native,” noncrystalline state. Recently, atomic or near-atomic resolution structures of several viruses and protein assemblies have been determined by single-particle cryoEM, allowing ab initio atomic model building by following the amino acid side chains or nucleic acid bases identifiable in their cryoEM density maps. In particular, these cryoEM structures have revealed extended arms contributing to molecular interactions that are otherwise not resolved by the conventional structural method of X-ray crystallography at similar resolutions. High-resolution cryoEM requires careful consideration of a number of factors, including proper sample preparation to ensure structural homogeneity, optimal configuration of electron imaging conditions to record high-resolution cryoEM images, accurate determination of image parameters to correct image distortions, efficient refinement and computation to reconstruct a 3D density map, and finally appropriate choice of modeling tools to construct atomic models for functional interpretation. This progress illustrates the power of cryoEM and ushers it into the arsenal of structural biology, alongside conventional techniques of X-ray crystallography and NMR, as a major tool (and sometimes the preferred one) for the studies of molecular interactions in supramolecular assemblies or machines. PMID:21501817

  13. Reliable modeling of the electronic spectra of realistic uranium complexes

    NASA Astrophysics Data System (ADS)

    Tecmer, Paweł; Govind, Niranjan; Kowalski, Karol; de Jong, Wibe A.; Visscher, Lucas

    2013-07-01

    We present an EOMCCSD (equation of motion coupled cluster with singles and doubles) study of excited states of the small [UO2]2+ and [UO2]+ model systems as well as the larger UVIO2(saldien) complex. In addition, the triples contribution within the EOMCCSDT and CR-EOMCCSD(T) (completely renormalized EOMCCSD with non-iterative triples) approaches for the [UO2]2+ and [UO2]+ systems as well as the active-space variant of the CR-EOMCCSD(T) method—CR-EOMCCSd(t)—for the UVIO2(saldien) molecule are investigated. The coupled cluster data were employed as benchmark to choose the "best" appropriate exchange-correlation functional for subsequent time-dependent density functional (TD-DFT) studies on the transition energies for closed-shell species. Furthermore, the influence of the saldien ligands on the electronic structure and excitation energies of the [UO2]+ molecule is discussed. The electronic excitations as well as their oscillator dipole strengths modeled with TD-DFT approach using the CAM-B3LYP exchange-correlation functional for the [UVO2(saldien)]- with explicit inclusion of two dimethyl sulfoxide molecules are in good agreement with the experimental data of Takao et al. [Inorg. Chem. 49, 2349 (2010), 10.1021/ic902225f].

  14. The role of habitat complexity in community development is mediated by resource availability.

    PubMed

    Smith, Rachel S; Johnston, Emma L; Clark, Graeme F

    2014-01-01

    Habitat complexity strongly affects the structure and dynamics of ecological communities, with increased complexity often leading to greater species diversity and abundance. However, habitat complexity changes as communities develop, and some species alter their environment to themselves provide habitat for other species. Most experimental studies manipulate basal substrate complexity, and while the importance of complexity likely changes during community development, few studies have examined the temporal dynamics of this variable. We used two experiments to quantify the importance of basal substrate complexity to sessile marine invertebrate community development through space and time. First, we compared effects of substrate complexity at 70 sites across ten estuaries. Sites differed in recruitment and community development rates, and after three months provided spatial variation in community development stage. Second, we tested for effects of substrate complexity at multiple times at a single site. In both experiments, complexity affected marine sessile invertebrate community composition in the early stages of community development when resource availability was high. Effects of complexity diminished through time as the amount of available space (the primary limiting resource) declined. Our work suggests the presence of a bare-space threshold, at which structural complexity of the basal substrate is overwhelmed by secondary biotic complexity. This threshold will be met at different times depending on local recruitment and growth rates and is likely to vary with productivity gradients.

  15. The Role of Habitat Complexity in Community Development Is Mediated by Resource Availability

    PubMed Central

    Smith, Rachel S.; Johnston, Emma L.; Clark, Graeme F.

    2014-01-01

    Habitat complexity strongly affects the structure and dynamics of ecological communities, with increased complexity often leading to greater species diversity and abundance. However, habitat complexity changes as communities develop, and some species alter their environment to themselves provide habitat for other species. Most experimental studies manipulate basal substrate complexity, and while the importance of complexity likely changes during community development, few studies have examined the temporal dynamics of this variable. We used two experiments to quantify the importance of basal substrate complexity to sessile marine invertebrate community development through space and time. First, we compared effects of substrate complexity at 70 sites across ten estuaries. Sites differed in recruitment and community development rates, and after three months provided spatial variation in community development stage. Second, we tested for effects of substrate complexity at multiple times at a single site. In both experiments, complexity affected marine sessile invertebrate community composition in the early stages of community development when resource availability was high. Effects of complexity diminished through time as the amount of available space (the primary limiting resource) declined. Our work suggests the presence of a bare-space threshold, at which structural complexity of the basal substrate is overwhelmed by secondary biotic complexity. This threshold will be met at different times depending on local recruitment and growth rates and is likely to vary with productivity gradients. PMID:25054325

  16. Internest food sharing within wood ant colonies: resource redistribution behavior in a complex system

    PubMed Central

    Robinson, Elva J.H.

    2016-01-01

    Resource sharing is an important cooperative behavior in many animals. Sharing resources is particularly important in social insect societies, as division of labor often results in most individuals including, importantly, the reproductives, relying on other members of the colony to provide resources. Sharing resources between individuals is therefore fundamental to the success of social insects. Resource sharing is complicated if a colony inhabits several spatially separated nests, a nesting strategy common in many ant species. Resources must be shared not only between individuals in a single nest but also between nests. We investigated the behaviors facilitating resource redistribution between nests in a dispersed-nesting population of wood ant Formica lugubris. We marked ants, in the field, as they transported resources along the trails between nests of a colony, to investigate how the behavior of individual workers relates to colony-level resource exchange. We found that workers from a particular nest “forage” to other nests in the colony, treating them as food sources. Workers treating other nests as food sources means that simple, pre-existing foraging behaviors are used to move resources through a distributed system. It may be that this simple behavioral mechanism facilitates the evolution of this complex life-history strategy. PMID:27004016

  17. Visualization of macromolecular complexes using cryo-electron microscopy with FEI Tecnai transmission electron microscopes

    PubMed Central

    Grassucci, Robert A; Taylor, Derek; Frank, Joachim

    2009-01-01

    This protocol details the steps used for visualizing the frozen-hydrated grids as prepared following the accompanying protocol entitled ‘Preparation of macromolecular complexes for visualization using cryo-electron microscopy.’ This protocol describes how to transfer the grid to the microscope using a standard cryo-transfer holder or, alternatively, using a cryo-cartridge loading system, and how to collect low-dose data using an FEI Tecnai transmission electron microscope. This protocol also summarizes and compares the various options that are available in data collection for three-dimensional (3D) single-particle reconstruction. These options include microscope settings, choice of detectors and data collection strategies both in situations where a 3D reference is available and in the absence of such a reference (random-conical and common lines). PMID:18274535

  18. Connecting knowledge resources to the veterinary electronic health record: opportunities for learning at point of care.

    PubMed

    Alpi, Kristine M; Burnett, Heidi A; Bryant, Sheila J; Anderson, Katherine M

    2011-01-01

    Electronic health records (EHRs) provide clinical learning opportunities through quick and contextual linkage of patient signalment, symptom, and diagnosis data with knowledge resources covering tests, drugs, conditions, procedures, and client instructions. This paper introduces the EHR standards for linkage and the partners-practitioners, content publishers, and software developers-necessary to leverage this possibility in veterinary medicine. The efforts of the American Animal Hospital Association (AAHA) Electronic Health Records Task Force to partner with veterinary practice management systems to improve the use of controlled vocabulary is a first step in the development of standards for sharing knowledge at the point of care. The Veterinary Medical Libraries Section (VMLS) of the Medical Library Association's Task Force on Connecting the Veterinary Health Record to Information Resources compiled a list of resources of potential use at point of care. Resource details were drawn from product Web sites and organized by a metric used to evaluate medical point-of-care resources. Additional information was gathered from questions sent by e-mail and follow-up interviews with two practitioners, a hospital network, two software developers, and three publishers. Veterinarians with electronic records use a variety of information resources that are not linked to their software. Systems lack the infrastructure to use the Infobutton standard that has been gaining popularity in human EHRs. While some veterinary knowledge resources are digital, publisher sites and responses do not indicate a Web-based linkage of veterinary resources with EHRs. In order to facilitate lifelong learning and evidence-based practice, veterinarians and educators of future practitioners must demonstrate to veterinary practice software developers and publishers a clinically-based need to connect knowledge resources to veterinary EHRs.

  19. Disseminating Context-Specific Access to Online Knowledge Resources within Electronic Health Record Systems

    PubMed Central

    Fiol, Guilherme Del; Curtis, Clayton; Cimino, James J.; Iskander, Andrew; Kalluri, Aditya S.D.; Jing, Xia; Hulse, Nathan C.; Long, Jie; Overby, Casey L.; Schardt, Connie; Douglas, David M.

    2013-01-01

    Clinicians’ patient care information needs are frequent and largely unmet. Online knowledge resources are available that can help clinicians meet these information needs. Yet, significant barriers limit the use of these resources within the clinical workflow. Infobuttons are clinical decision support tools that use the clinical context (e.g., institution, user, patient) within electronic health record (EHR) systems to anticipate clinicians’ questions and provide automated links to relevant information in knowledge resources. This paper describes OpenInfobutton (www.openinfobutton.org): a standards-based, open source Web service that was designed to disseminate infobutton capabilities in multiple EHR systems and healthcare organizations. OpenInfobutton has been successfully integrated with 38 knowledge resources at 5 large healthcare organizations in the United States. We describe the OpenInfobutton architecture, knowledge resource integration, and experiences at five large healthcare organizations. PMID:23920641

  20. Iron Hill (Powderhorn) carbonatite complex, Gunnison County, CO - A potential source of several uncommon mineral resources

    USGS Publications Warehouse

    Van Gosen, B. S.; Lowers, H.A.

    2007-01-01

    The Iron Hill (Powderhorn) carbonatite complex is a 31-kM2 (12-sq mile) alkalic intrusion located about 35 km (22 miles) south-southwest of Gunnison, CO. The intrusion has been well studied and described because of its classic petrology and architecture ofa carbonatite-alkalic complex. The complex is also noteworthy because it contains enrichments of titanium, rare earth elements, thorium, niobium (columbium), vanadium and deposits of vermiculite and nepheline syenite. In particular, the complex is thought to host the largest titanium and niobium resources in the United States, although neither has been developed. It may be economic to extract multiple resources from this complex with a well-coordinated mine and mill plan.

  1. Electron collisions with the CH2O-H2O complex

    NASA Astrophysics Data System (ADS)

    Freitas, T. C.; Bettega, M. H. F.; Lima, M. A. P.; Canuto, S.

    2009-11-01

    In this conference we will present cross sections for elastic electron collisions with the CH2O-H2O complex bonded through hydrogen bond. We will investigate electron collisions with different structures of this complex which were obtained by Classical Monte Carlo simulations. This work would help in understanding the hole of water in the dissociative electron attachment in biological molecules.

  2. A framework for unravelling the complexities of unsustainable water resource use

    NASA Astrophysics Data System (ADS)

    Dermody, Brian; Bierkens, Marc; Wassen, Martin; Dekker, Stefan

    2016-04-01

    The majority of unsustainable water resource use is associated with food production, with the agricultural sector accounting for up to 70% of total freshwater use by humans. Water resource use in food production emerges as a result of dynamic interactions between humans and their environment in importing and exporting regions as well as the physical and socioeconomic trade infrastructure linking the two. Thus in order to understand unsustainable water resource use, it is essential to understand the complex socioecological food production and trade system. We present a modelling framework of the food production and trade system that facilitates an understanding of complex socioenvironmental processes that lead to unsustainable water resource use. Our framework is based on a coupling of the global hydrological model PC Raster Global Water Balance (PCR-GLOBWB) with a multi-agent socioeconomic food production and trade network. In our framework, agents perceive environmental conditions. They make food supply decisions based upon those perceptions and the heterogeneous socioeconomic conditions in which they exist. Agent decisions modify land and water resources. Those environmental changes feedback to influence decision making further. The framework presented has the potential to go beyond a diagnosis of the causes of unsustainable water resource and provide pathways towards a sustainable food system in terms of water resources.

  3. The Collaborative Cross, a community resource for the genetic analysis of complex traits.

    PubMed

    Churchill, Gary A; Airey, David C; Allayee, Hooman; Angel, Joe M; Attie, Alan D; Beatty, Jackson; Beavis, William D; Belknap, John K; Bennett, Beth; Berrettini, Wade; Bleich, Andre; Bogue, Molly; Broman, Karl W; Buck, Kari J; Buckler, Ed; Burmeister, Margit; Chesler, Elissa J; Cheverud, James M; Clapcote, Steven; Cook, Melloni N; Cox, Roger D; Crabbe, John C; Crusio, Wim E; Darvasi, Ariel; Deschepper, Christian F; Doerge, R W; Farber, Charles R; Forejt, Jiri; Gaile, Daniel; Garlow, Steven J; Geiger, Hartmut; Gershenfeld, Howard; Gordon, Terry; Gu, Jing; Gu, Weikuan; de Haan, Gerald; Hayes, Nancy L; Heller, Craig; Himmelbauer, Heinz; Hitzemann, Robert; Hunter, Kent; Hsu, Hui-Chen; Iraqi, Fuad A; Ivandic, Boris; Jacob, Howard J; Jansen, Ritsert C; Jepsen, Karl J; Johnson, Dabney K; Johnson, Thomas E; Kempermann, Gerd; Kendziorski, Christina; Kotb, Malak; Kooy, R Frank; Llamas, Bastien; Lammert, Frank; Lassalle, Jean-Michel; Lowenstein, Pedro R; Lu, Lu; Lusis, Aldons; Manly, Kenneth F; Marcucio, Ralph; Matthews, Doug; Medrano, Juan F; Miller, Darla R; Mittleman, Guy; Mock, Beverly A; Mogil, Jeffrey S; Montagutelli, Xavier; Morahan, Grant; Morris, David G; Mott, Richard; Nadeau, Joseph H; Nagase, Hiroki; Nowakowski, Richard S; O'Hara, Bruce F; Osadchuk, Alexander V; Page, Grier P; Paigen, Beverly; Paigen, Kenneth; Palmer, Abraham A; Pan, Huei-Ju; Peltonen-Palotie, Leena; Peirce, Jeremy; Pomp, Daniel; Pravenec, Michal; Prows, Daniel R; Qi, Zhonghua; Reeves, Roger H; Roder, John; Rosen, Glenn D; Schadt, Eric E; Schalkwyk, Leonard C; Seltzer, Ze'ev; Shimomura, Kazuhiro; Shou, Siming; Sillanpää, Mikko J; Siracusa, Linda D; Snoeck, Hans-Willem; Spearow, Jimmy L; Svenson, Karen; Tarantino, Lisa M; Threadgill, David; Toth, Linda A; Valdar, William; de Villena, Fernando Pardo-Manuel; Warden, Craig; Whatley, Steve; Williams, Robert W; Wiltshire, Tim; Yi, Nengjun; Zhang, Dabao; Zhang, Min; Zou, Fei

    2004-11-01

    The goal of the Complex Trait Consortium is to promote the development of resources that can be used to understand, treat and ultimately prevent pervasive human diseases. Existing and proposed mouse resources that are optimized to study the actions of isolated genetic loci on a fixed background are less effective for studying intact polygenic networks and interactions among genes, environments, pathogens and other factors. The Collaborative Cross will provide a common reference panel specifically designed for the integrative analysis of complex systems and will change the way we approach human health and disease.

  4. Use of electronic sales data to tailor nutrition education resources for an ethnically diverse population.

    PubMed

    Eyles, H; Rodgers, A; Ni Mhurchu, C

    2010-02-01

    Nutrition education may be most effective when personally tailored. Individualised electronic supermarket sales data offer opportunities to tailor nutrition education using shopper's usual food purchases. The present study aimed to use individualised electronic supermarket sales data to tailor nutrition resources for an ethnically diverse population in a large supermarket intervention trial in New Zealand. Culturally appropriate nutrition education resources (i.e. messages and shopping lists) were developed with the target population (through two sets of focus groups) and ethnic researchers. A nutrient database of supermarket products was developed using retrospective sales data and linked to participant sales to allow tailoring by usual food purchases. Modified Heart Foundation Tick criteria were used to identify 'healthier' products in the database suitable for promotion in the resources. Rules were developed to create a monthly report listing the tailored and culturally targeted messages to be sent to each participant, and to produce automated, tailored shopping lists. Culturally targeted nutrition messages (n = 864) and shopping lists (n = 3 formats) were developed. The food and nutrient database (n = 3000 top-selling products) was created using 12 months of retrospective sales data, and comprised 60%'healthier' products. Three months of baseline sales data were used to determine usual food purchases. Tailored resources were successfully mailed to 123 Māori, 52 Pacific and 346 non-Māori non-Pacific participants over the 6-month trial intervention period. Electronic supermarket sales data can be used to tailor nutrition education resources for a large number of ethnically diverse supermarket shoppers.

  5. Managing Electronic Resources: A Survey of Current Practices in Academic Libraries.

    ERIC Educational Resources Information Center

    Shaw, Beth Hansen

    This document reports results of an online survey that examined practices and procedures in the management of electronic resources in 65 academic library reference departments. Responses are related to: (1) student population; (2) library use by community people; (3) number of public access workstations, workstations with World Wide Web access,…

  6. Use of Electronic Information Resources among Research Scholars in the Islamia University of Bahawalpur, Pakistan

    ERIC Educational Resources Information Center

    Amjad, Anam; Ahmed, Shamshad; Bin Naeem, Salman

    2013-01-01

    This study examined the use of electronic resources among academic scholars of The Islamia University of Bahawalpur (IUB), Punjab, Pakistan. A quantitative survey was found most convenient and useful for this study. The total population of the study was 169 research students in IUB. The response rate was 79% and 133 utilizable responses were coded…

  7. Implementation of an Electronic Resource Assessment System in an Academic Library

    ERIC Educational Resources Information Center

    Xu, Fei

    2010-01-01

    Purpose: The purpose of this paper is to provide a library with useful information about selection criteria for an electronic resource assessment system and practical assistance on how to implement efficiently such a system. Design/methodology/approach: The paper is based on literature review, desk research, and implementation experience.…

  8. The Acquisition and Management of Electronic Resources: Can Use Justify Cost?

    ERIC Educational Resources Information Center

    Koehn, Shona L.; Hawamdeh, Suliman

    2010-01-01

    As library collections increasingly become digital, libraries are faced with many challenges regarding the acquisition and management of electronic resources. Some of these challenges include copyright and fair use, the first-sale doctrine, licensing versus ownership, digital preservation, long-term archiving, and, most important, the issue of…

  9. A Survey of the Use of Electronic Resources at Seven Universities in Wuhan, China

    ERIC Educational Resources Information Center

    Zhang, Liyi; Ye, Pinghao; Liu, Qihua

    2011-01-01

    Purpose: The purpose of this paper is to report on users' information behaviour in China, a topic which has not been researched extensively. The aim is to help producers and providers collect and develop more electronic resources. Design/methodology/approach: The study investigates users' information behaviour at seven "211 Project"…

  10. Resource and Referral Service: A Report on Electronic Networks for Educators.

    ERIC Educational Resources Information Center

    Gordon, Ruth; Smink, Jay

    This report describes the activities of the Resource and Referral Service (RRS), which was established in 1977 as a member of a nationwide dissemination network called the Research and Development Exchange (RDx), in using electronic networks as part of its dissemination effort. Discussed first are the history and objectives of RRS. The next…

  11. A Survey of the Use of Electronic Resources at Seven Universities in Wuhan, China

    ERIC Educational Resources Information Center

    Zhang, Liyi; Ye, Pinghao; Liu, Qihua

    2011-01-01

    Purpose: The purpose of this paper is to report on users' information behaviour in China, a topic which has not been researched extensively. The aim is to help producers and providers collect and develop more electronic resources. Design/methodology/approach: The study investigates users' information behaviour at seven "211 Project"…

  12. Electronics/Electromechanical Technology. Instructional Resource Guide for Competency Based Education.

    ERIC Educational Resources Information Center

    Kuchinsky, Charlotte A.

    This instructional resource guide is intended to aid teachers and curriculum specialists in developing instructional materials for the first two years of preparation of electronics technicians. It is part of the secondary/postsecondary master technician program. Section I on occupational information presents general information and the…

  13. Selection and Presentation of Commercially Available Electronic Resources: Issues and Practices.

    ERIC Educational Resources Information Center

    Jewell, Timothy D.

    This report focuses on practices related to the selection and presentation of commercially available electronic resources. As part of the Digital Library Federation's Collection Practices Initiative, the report also shares the goal of identifying and propagating practices that support the growth of sustainable and scalable collections. It looks in…

  14. EDI (electronic data interchange) for human resources saves money and time.

    PubMed

    Moynihan, J J; Kibat, G

    1994-01-01

    Healthcare financial managers seeking immediate cost savings through the use of electronic data interchange (EDI) may find that the automation of repetitive transactions can reduce staffing levels in hospital human resource departments and lower the cost of employee benefits. New procedures and EDI also can tighten controls on hospital employee health benefit eligibility and reduce the per employee cost of benefits.

  15. The Acquisition and Management of Electronic Resources: Can Use Justify Cost?

    ERIC Educational Resources Information Center

    Koehn, Shona L.; Hawamdeh, Suliman

    2010-01-01

    As library collections increasingly become digital, libraries are faced with many challenges regarding the acquisition and management of electronic resources. Some of these challenges include copyright and fair use, the first-sale doctrine, licensing versus ownership, digital preservation, long-term archiving, and, most important, the issue of…

  16. Electronic Resources and Academic Libraries, 1980-2000: A Historical Perspective.

    ERIC Educational Resources Information Center

    Miller, Ruth H.

    2000-01-01

    Over the past 20 years, academic collection development specialists have dealt with changes, brought about by decreasing purchasing power and the growing importance of electronic resources. Throughout, collection managers have rethought their efforts and revised criteria for selection of materials in new formats while maintaining traditional…

  17. Internet Resources on Women: Using Electronic Media in Curriculum Transformation. Women in the Curriculum Series.

    ERIC Educational Resources Information Center

    Korenman, Joan

    This manual has been written primarily for internet novices and for people already familiar with online communications who want to learn more about the growing array of electronic resources pertaining to Women's Studies and to transforming the curriculum so that it better reflects women's experience, accomplishments, and perspectives. Chapter 1…

  18. Oklahoma Library Technology Network (OLTN) Electronic Resources for Elementary Age Children.

    ERIC Educational Resources Information Center

    Fox, Carol, Comp.

    This document describes Oklahoma Library Technology Network electronic resources for elementary age children. The first section provides a history of Oklahoma statewide shared databases. Oklahoma statewide information database contacts are listed in the second section. The third section presents information on InfoTrac Kid's Edition Online…

  19. Using Electronic Information Resources Centers by Faculty Members at University Education: Competencies, Needs and Challenges

    ERIC Educational Resources Information Center

    Abouelenein, Yousri

    2017-01-01

    This study aimed at investigating the factual situation of electronic information resources centers to faculty members at university education. Competencies that faculty members should possess regarding this issue were determined. Also their needs for (scientific research skills and teaching) were assessed. In addition, problems that hinder their…

  20. Electronic Energy transfer in light-harvesting antenna complexes

    NASA Astrophysics Data System (ADS)

    Hossein-Nejad, Hoda

    The studies presented in this thesis explore electronic energy transfer (EET) in light-harvesting antenna complexes and investigate the role of quantum coherence in EET. The dynamics of energy transfer are investigated in three distinct length scales and a different formulation of the exciton transport problem is applied at each scale. These scales include: the scale of a molecular dimer, the scale of a single protein and the scale of a molecular aggregate. The antenna protein phycoerythrin 545 (PE545) isolated from the photosynthetic cryptophyte algae Rhodomonas CS4 is specifically studied in two chapters of this thesis. It is found that formation of small aggregates delocalizes the excitation across chromophores of adjacent proteins, and that this delocalization has a dramatic effect in enhancing the rate of energy transfer between pigments. Furthermore, we investigate EET from a donor to an acceptor via an intermediate site and observe that interference of coherent pathways gives a finite correction to the transfer rate that is sensitively dependent on the nature of the vibrational interactions in the system. The statistical fluctuations of a system exhibiting EET are investigated in the final chapter. The techniques of non-equilibrium statistical mechanics are applied to investigate the steady-state of a typical system exhibiting EET that is perturbed out of equilibrium due to its interaction with a fluctuating bath.

  1. Cryo-Electron Tomography for Structural Characterization of Macromolecular Complexes

    PubMed Central

    Cope, Julia; Heumann, John; Hoenger, Andreas

    2011-01-01

    Cryo-electron tomography (cryo-ET) is an emerging 3-D reconstruction technology that combines the principles of tomographic 3-D reconstruction with the unmatched structural preservation of biological material embedded in vitreous ice. Cryo-ET is particularly suited to investigating cell-biological samples and large macromolecular structures that are too polymorphic to be reconstructed by classical averaging-based 3-D reconstruction procedures. This unit aims to make cryo-ET accessible to newcomers and discusses the specialized equipment required, as well as the relevant advantages and hurdles associated with sample preparation by vitrification and cryo-ET. Protocols describe specimen preparation, data recording and 3-D data reconstruction for cryo-ET, with a special focus on macromolecular complexes. A step-by-step procedure for specimen vitrification by plunge freezing is provided, followed by the general practicalities of tilt-series acquisition for cryo-ET, including advice on how to select an area appropriate for acquiring a tilt series. A brief introduction to the underlying computational reconstruction principles applied in tomography is described, along with instructions for reconstructing a tomogram from cryo-tilt series data. Finally, a method is detailed for extracting small subvolumes containing identical macromolecular structures from tomograms for alignment and averaging as a means to increase the signal-to-noise ratio and eliminate missing wedge effects inherent in tomographic reconstructions. PMID:21842467

  2. Cryo-electron tomography for structural characterization of macromolecular complexes.

    PubMed

    Cope, Julia; Heumann, John; Hoenger, Andreas

    2011-08-01

    Cryo-electron tomography (cryo-ET) is an emerging 3-D reconstruction technology that combines the principles of tomographic 3-D reconstruction with the unmatched structural preservation of biological matter embedded in vitreous ice. Cryo-ET is particularly suited to investigating cell-biological samples and large macromolecular structures that are too polymorphic to be reconstructed by classical averaging-based 3-D reconstruction procedures. This unit aims to make cryo-ET accessible to newcomers and discusses the specialized equipment required, as well as relevant advantages and hurdles associated with sample preparation by vitrification and cryo-ET. Protocols describe specimen preparation, data recording and 3-D data reconstruction for cryo-ET, with a special focus on macromolecular complexes. A step-by-step procedure for specimen vitrification by plunge freezing is provided, followed by the general practicalities of tilt-series acquisition for cryo-ET, including advice on how to select an area appropriate for acquiring a tilt series. A brief introduction to the underlying computational reconstruction principles applied in tomography is described, along with instructions for reconstructing a tomogram from cryo-tilt series data. Finally, a method is detailed for extracting small subvolumes containing identical macromolecular structures from tomograms for alignment and averaging as a means to increase the signal-to-noise ratio and eliminate missing wedge effects inherent in tomographic reconstructions.

  3. A sequential learning algorithm for complex-valued self-regulating resource allocation network-CSRAN.

    PubMed

    Suresh, Sundaram; Savitha, Ramasamy; Sundararajan, Narasimhan

    2011-07-01

    This paper presents a sequential learning algorithm for a complex-valued resource allocation network with a self-regulating scheme, referred to as complex-valued self-regulating resource allocation network (CSRAN). The self-regulating scheme in CSRAN decides what to learn, when to learn, and how to learn based on the information present in the training samples. CSRAN is a complex-valued radial basis function network with a sech activation function in the hidden layer. The network parameters are updated using a complex-valued extended Kalman filter algorithm. CSRAN starts with no hidden neuron and builds up an appropriate number of hidden neurons, resulting in a compact structure. Performance of the CSRAN is evaluated using a synthetic complex-valued function approximation problem, two real-world applications consisting of a complex quadrature amplitude modulation channel equalization, and an adaptive beam-forming problem. Since complex-valued neural networks are good decision makers, the decision-making ability of the CSRAN is compared with other complex-valued classifiers and the best performing real-valued classifier using two benchmark unbalanced classification problems from UCI machine learning repository. The approximation and classification results show that the CSRAN outperforms other existing complex-valued learning algorithms available in the literature.

  4. LUNAR DUST GRAIN CHARGING BY ELECTRON IMPACT: COMPLEX ROLE OF SECONDARY ELECTRON EMISSIONS IN SPACE ENVIRONMENTS

    SciTech Connect

    Abbas, M. M.; Craven, P. D.; LeClair, A. C.; Spann, J. F.; Tankosic, D.

    2010-08-01

    Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions (SEEs). The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. Knowledge of the dust grain charges and equilibrium potentials is important for understanding a variety of physical and dynamical processes in the interstellar medium, and heliospheric, interplanetary/planetary, and lunar environments. It has been well recognized that the charging properties of individual micron-/submicron-size dust grains are expected to be substantially different from the corresponding values for bulk materials. In this paper, we present experimental results on the charging of individual 0.2-13 {mu}m size dust grains selected from Apollo 11 and 17 dust samples, and spherical silica particles by exposing them to mono-energetic electron beams in the 10-200 eV energy range. The dust charging process by electron impact involving the SEEs discussed is found to be a complex charging phenomenon with strong particle size dependence. The measurements indicate substantial differences between the polarity and magnitude of the dust charging rates of individual small-size dust grains, and the measurements and model properties of corresponding bulk materials. A more comprehensive plan of measurements of the charging properties of individual dust grains for developing a database for realistic models of dust charging in astrophysical and lunar environments is in progress.

  5. Lunary Dust Grain Charging by Electron Impact: Complex Role of Secondary Electron Emissions in Space Environments

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Tankosic, D.; Crave, P. D.; LeClair, A.; Spann, J. F.

    2010-01-01

    Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions (SEES). The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. Knowledge of the dust grain charges and equilibrium potentials is important for understanding a variety of physical and dynamical processes in the interstellar medium, and heliospheric, interplanetary/ planetary, and lunar environments. It has been well recognized that the charging properties of individual micron-/submicron-size dust grains are expected to be substantially different from the corresponding values for bulk materials. In this paper, we present experimental results on the charging of individual 0.2-13 m size dust grains selected from Apollo 11 and 17 dust samples, and spherical silica particles by exposing them to mono-energetic electron beams in the 10-200 eV energy range. The dust charging process by electron impact involving the SEES discussed is found to be a complex charging phenomenon with strong particle size dependence. The measurements indicate substantial differences between the polarity and magnitude of the dust charging rates of individual small-size dust grains, and the measurements and model properties of corresponding bulk materials. A more comprehensive plan of measurements of the charging properties of individual dust grains for developing a database for realistic models of dust charging in astrophysical and lunar environments is in progress.

  6. Lunar Dust Grain Charging by Electron Impact: Complex Role of Secondary Electron Emissions in Space Environments

    NASA Astrophysics Data System (ADS)

    Abbas, M. M.; Tankosic, D.; Craven, P. D.; LeClair, A. C.; Spann, J. F.

    2010-08-01

    Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions (SEEs). The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. Knowledge of the dust grain charges and equilibrium potentials is important for understanding a variety of physical and dynamical processes in the interstellar medium, and heliospheric, interplanetary/planetary, and lunar environments. It has been well recognized that the charging properties of individual micron-/submicron-size dust grains are expected to be substantially different from the corresponding values for bulk materials. In this paper, we present experimental results on the charging of individual 0.2-13 μm size dust grains selected from Apollo 11 and 17 dust samples, and spherical silica particles by exposing them to mono-energetic electron beams in the 10-200 eV energy range. The dust charging process by electron impact involving the SEEs discussed is found to be a complex charging phenomenon with strong particle size dependence. The measurements indicate substantial differences between the polarity and magnitude of the dust charging rates of individual small-size dust grains, and the measurements and model properties of corresponding bulk materials. A more comprehensive plan of measurements of the charging properties of individual dust grains for developing a database for realistic models of dust charging in astrophysical and lunar environments is in progress.

  7. Use of poisons information resources and satisfaction with electronic products by Victorian emergency department staff.

    PubMed

    Luke, Stephen; Fountain, John S; Reith, David M; Braitberg, George; Cruickshank, Jaycen

    2014-10-01

    ED staff use a range of poisons information resources of varying type and quality. The present study aims to identify those resources utilised in the state of Victoria, Australia, and assess opinion of the most used electronic products. A previously validated self-administered survey was conducted in 15 EDs, with 10 questionnaires sent to each. The survey was then repeated following the provision of a 4-month period of access to Toxinz™, an Internet poisons information product novel to the region. The study was conducted from December 2010 to August 2011. There were 117 (78%) and 48 (32%) responses received from the first and second surveys, respectively, a 55% overall response rate. No statistically significant differences in professional group, numbers of poisoned patients seen or resource type accessed were identified between studies. The electronic resource most used in the first survey was Poisindex® (48.68%) and Toxinz™ (64.1%) in the second. There were statistically significant (P < 0.01) improvements in satisfaction in 26 of 42 questions between surveys, and no decrements. Although the majority of responders possessed mobile devices, less than half used them for poisons information but would do so if a reputable product was available. The order of poisons information sources most utilised was: consultation with a colleague, in-house protocols and electronic resources. There was a significant difference in satisfaction with electronic poisons information resources and a movement away from existing sources when choice was provided. Interest in increased use of mobile solutions was identified. © 2014 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

  8. Speech as a breakthrough signaling resource in the cognitive evolution of biological complex adaptive systems.

    PubMed

    Mattei, Tobias A

    2014-12-01

    In self-adapting dynamical systems, a significant improvement in the signaling flow among agents constitutes one of the most powerful triggering events for the emergence of new complex behaviors. Ackermann and colleagues' comprehensive phylogenetic analysis of the brain structures involved in acoustic communication provides further evidence of the essential role which speech, as a breakthrough signaling resource, has played in the evolutionary development of human cognition viewed from the standpoint of complex adaptive system analysis.

  9. Power resource management and low-power remote wireless RF electronics

    NASA Astrophysics Data System (ADS)

    Jannson, Tomasz; Forrester, Thomas; Degrood, Kevin; Lee, Kang; Gans, Eric; Walter, Kevin

    2009-05-01

    Battery power resource management becomes a critical issue in the case of self-powered remote wireless RF electronics, where the basic parameter is time of system operation before battery recharging or battery replacement. In such cases, very often related to physical protection against antitampering (AT), proper theoretical modeling of a battery driven power supply in the context of a given digital electronic system is of utmost importance. Such modeling should include various types of batteries (primary and secondary), various self-discharge processes in different temperatures, and even energy harvesting, the latter to supply power for long-term content, low-power electronic subsystems. In this paper we analyze simple modeling of resource power management, including variations of all of these parameters and energy harvesting.

  10. Integrating Genomic Resources with Electronic Health Records using the HL7 Infobutton Standard

    PubMed Central

    Overby, Casey Lynnette; Del Fiol, Guilherme; Rubinstein, Wendy S.; Maglott, Donna R.; Nelson, Tristan H.; Milosavljevic, Aleksandar; Martin, Christa L.; Goehringer, Scott R.; Freimuth, Robert R.; Williams, Marc S.

    2016-01-01

    Summary Background The Clinical Genome Resource (ClinGen) Electronic Health Record (EHR) Workgroup aims to integrate ClinGen resources with EHRs. A promising option to enable this integration is through the Health Level Seven (HL7) Infobutton Standard. EHR systems that are certified according to the US Meaningful Use program provide HL7-compliant infobutton capabilities, which can be leveraged to support clinical decision-making in genomics. Objectives To integrate genomic knowledge resources using the HL7 infobutton standard. Two tactics to achieve this objective were: (1) creating an HL7-compliant search interface for ClinGen, and (2) proposing guidance for genomic resources on achieving HL7 Infobutton standard accessibility and compliance. Methods We built a search interface utilizing OpenInfobutton, an open source reference implementation of the HL7 Infobutton standard. ClinGen resources were assessed for readiness towards HL7 compliance. Finally, based upon our experiences we provide recommendations for publishers seeking to achieve HL7 compliance. Results Eight genomic resources and two sub-resources were integrated with the ClinGen search engine via OpenInfobutton and the HL7 infobutton standard. Resources we assessed have varying levels of readiness towards HL7-compliance. Furthermore, we found that adoption of standard terminologies used by EHR systems is the main gap to achieve compliance. Conclusion Genomic resources can be integrated with EHR systems via the HL7 Infobutton standard using OpenInfobutton. Full compliance of genomic resources with the Infobutton standard would further enhance interoperability with EHR systems. PMID:27579472

  11. Identifying and evaluating electronic learning resources for use in adult-gerontology nurse practitioner education.

    PubMed

    Thompson, Hilaire J; Belza, Basia; Baker, Margaret; Christianson, Phyllis; Doorenbos, Ardith; Nguyen, Huong

    2014-01-01

    Enhancing existing curricula to meet newly published adult-gerontology advanced practice registered nurse (APRN) competencies in an efficient manner presents a challenge to nurse educators. Incorporating shared, published electronic learning resources (ELRs) in existing or new courses may be appropriate in order to assist students in achieving competencies. The purposes of this project were to (a) identify relevant available ELR for use in enhancing geriatric APRN education and (b) to evaluate the educational utility of identified ELRs based on established criteria. A multilevel search strategy was used. Two independent team members reviewed identified ELR against established criteria to ensure utility. Only resources meeting all criteria were retained. Resources were found for each of the competency areas and included formats such as podcasts, Web casts, case studies, and teaching videos. In many cases, resources were identified using supplemental strategies and not through traditional search or search of existing geriatric repositories. Resources identified have been useful to advanced practice educators in improving lecture and seminar content in a particular topic area and providing students and preceptors with additional self-learning resources. Addressing sustainability within geriatric APRN education is critical for sharing of best practices among educators and for sustainability of teaching and related resources.

  12. Modelling of electron beam absorption in complex geometries

    NASA Astrophysics Data System (ADS)

    Klassen, Alexander; Bauereiß, Andreas; Körner, Carolin

    2014-02-01

    Computational modelling of processes that involve highly energetic electrons like electron beam melting, welding, drilling or electron beam lithography, to name but a few, requires information about the attenuation of the electron beam as it passes through the sample. Depth-dose curves as a function of electron energy, target material as well as local surface obliquity have to be provided in situ during the calculation. The most efficient way to address this issue is by employing mathematical expressions. Therefore, we propose an electron beam model based on a set of semi-empirical equations available from different published literature and on theoretical considerations. Particular stress is thereby put on accuracy and the range of validity of the theoretical approach by comparison with experimental data. Finally, we apply our model to powder-bed based additive manufacturing. The numerical results demonstrate that electron beam absorption and depth of penetration have a strong influence on the quality of the fabricated product.

  13. Integrated optimal allocation model for complex adaptive system of water resources management (II): Case study

    NASA Astrophysics Data System (ADS)

    Zhou, Yanlai; Guo, Shenglian; Xu, Chong-Yu; Liu, Dedi; Chen, Lu; Wang, Dong

    2015-12-01

    Climate change, rapid economic development and increase of the human population are considered as the major triggers of increasing challenges for water resources management. This proposed integrated optimal allocation model (IOAM) for complex adaptive system of water resources management is applied in Dongjiang River basin located in the Guangdong Province of China. The IOAM is calibrated and validated under baseline period 2010 year and future period 2011-2030 year, respectively. The simulation results indicate that the proposed model can make a trade-off between demand and supply for sustainable development of society, economy, ecology and environment and achieve adaptive management of water resources allocation. The optimal scheme derived by multi-objective evaluation is recommended for decision-makers in order to maximize the comprehensive benefits of water resources management.

  14. Availability, Level of Use and Constraints to Use of Electronic Resources by Law Lecturers in Public Universities in Nigeria

    ERIC Educational Resources Information Center

    Amusa, Oyintola Isiaka; Atinmo, Morayo

    2016-01-01

    (Purpose) This study surveyed the level of availability, use and constraints to use of electronic resources among law lecturers in Nigeria. (Methodology) Five hundred and fifty-two law lecturers were surveyed and four hundred and forty-two responded. (Results) Data analysis revealed that the level of availability of electronic resources for the…

  15. Bit by Bit: A Series of Trends, Tools, and Initiatives Are Aimed at Improving Electronic Resource Management

    ERIC Educational Resources Information Center

    Webster, Peter

    2006-01-01

    Electronic resources are more prominent than ever in library collections, yet they resist easy management. A range of tools and cooperative efforts are emerging to improve the management and evaluation of electronic resources. Initiatives are underway to standardize and automate the harvesting of usage statistics and e-journal title and holdings…

  16. Defining the Electronic and Geometric Structure of One-Electron Oxidized Copper–Bis-phenoxide Complexes

    PubMed Central

    Storr, Tim; Verma, Pratik; Pratt, Russell C.; Wasinger, Erik C.; Shimazaki, Yuichi; Stack, T. Daniel P.

    2009-01-01

    The geometric and electronic structure of an oxidized Cu complex ([CuSal]+; Sal = N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with a non-innocent salen ligand has been investigated both in the solid state and in solution. Integration of information from UV–vis–NIR spectroscopy, magnetic susceptibility, electrochemistry, resonance Raman spectroscopy, X-ray crystallography, X-ray absorption spectroscopy, and density functional theory calculations provides critical insights into the nature of the localization/delocalization of the oxidation locus. In contrast to the analogous Ni derivative [NiSal]+ (Storr, T.; et al. Angew. Chem., Int. Ed. 2007, 46, 5198), which exists solely in the Ni(II) ligand-radical form, the locus of oxidation is metal-based for [CuSal]+, affording exclusively a Cu(III) species in the solid state (4–300 K). Variable-temperature solution studies suggest that [CuSal]+ exists in a reversible spin-equilibrium between a ligand-radical species [Cu(II)Sal•]+ (S = 1) and the high-valent metal form [Cu(III)Sal]+ (S = 0), indicative of nearly isoenergetic species. It is surprising that a bis-imine–bis-phenolate ligation stabilizes the Cu(III) oxidation state, and even more surprising that in solution a spin equilibrium occurs without a change in coordination number. The oxidized tetrahydrosalen analogue [CuSalred]+ (Salred = N, N′-bis(3,5-di-tert-butylhydroxybenzyl)-1,2-cyclohexane-(1R,2R)-diamine) exists as a temperature-invariant Cu(II)–ligand-radical complex in solution, demonstrating that ostensibly simple variations of the ligand structure affect the locus of oxidation in Cu–bis-phenoxide complexes. PMID:18939830

  17. Defining the electronic and geometric structure of one-electron oxidized copper-bis-phenoxide complexes.

    PubMed

    Storr, Tim; Verma, Pratik; Pratt, Russell C; Wasinger, Erik C; Shimazaki, Yuichi; Stack, T Daniel P

    2008-11-19

    The geometric and electronic structure of an oxidized Cu complex ([CuSal](+); Sal = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with a non-innocent salen ligand has been investigated both in the solid state and in solution. Integration of information from UV-vis-NIR spectroscopy, magnetic susceptibility, electrochemistry, resonance Raman spectroscopy, X-ray crystallography, X-ray absorption spectroscopy, and density functional theory calculations provides critical insights into the nature of the localization/delocalization of the oxidation locus. In contrast to the analogous Ni derivative [NiSal](+) (Storr, T.; et al. Angew. Chem., Int. Ed. 2007, 46, 5198), which exists solely in the Ni(II) ligand-radical form, the locus of oxidation is metal-based for [CuSal](+), affording exclusively a Cu(III) species in the solid state (4-300 K). Variable-temperature solution studies suggest that [CuSal](+) exists in a reversible spin-equilibrium between a ligand-radical species [Cu(II)Sal(*)](+) (S = 1) and the high-valent metal form [Cu(III)Sal](+) (S = 0), indicative of nearly isoenergetic species. It is surprising that a bis-imine-bis-phenolate ligation stabilizes the Cu(III) oxidation state, and even more surprising that in solution a spin equilibrium occurs without a change in coordination number. The oxidized tetrahydrosalen analogue [CuSal(red)](+) (Sal(red) = N,N'-bis(3,5-di- tert-butylhydroxybenzyl)-1,2-cyclohexane-(1R,2R)-diamine) exists as a temperature-invariant Cu(II)-ligand-radical complex in solution, demonstrating that ostensibly simple variations of the ligand structure affect the locus of oxidation in Cu-bis-phenoxide complexes.

  18. Defining the Electronic And Geometric Structure of One-Electron Oxidized Copper-Bis-Phenoxide Complexes

    SciTech Connect

    Storr, T.; Verma, P.; Pratt, R.C.; Wasinger, E.C.; Shimazaki, Y.; Stack, T.D.P.

    2009-05-26

    The geometric and electronic structure of an oxidized Cu complex ([CuSal](+); Sal = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with a non-innocent salen ligand has been investigated both in the solid state and in solution. Integration of information from UV-vis-NIR spectroscopy, magnetic susceptibility, electrochemistry, resonance Raman spectroscopy, X-ray crystallography, X-ray absorption spectroscopy, and density functional theory calculations provides critical insights into the nature of the localization/delocalization of the oxidation locus. In contrast to the analogous Ni derivative [NiSal](+) (Storr, T.; et al. Angew. Chem., Int. Ed. 2007, 46, 5198), which exists solely in the Ni(II) ligand-radical form, the locus of oxidation is metal-based for [CuSal](+), affording exclusively a Cu(III) species in the solid state (4-300 K). Variable-temperature solution studies suggest that [CuSal](+) exists in a reversible spin-equilibrium between a ligand-radical species [Cu(II)Sal(*)](+) (S = 1) and the high-valent metal form [Cu(III)Sal](+) (S = 0), indicative of nearly isoenergetic species. It is surprising that a bis-imine-bis-phenolate ligation stabilizes the Cu(III) oxidation state, and even more surprising that in solution a spin equilibrium occurs without a change in coordination number. The oxidized tetrahydrosalen analogue [CuSal(red)](+) (Sal(red) = N,N'-bis(3,5-di- tert-butylhydroxybenzyl)-1,2-cyclohexane-(1R,2R)-diamine) exists as a temperature-invariant Cu(II)-ligand-radical complex in solution, demonstrating that ostensibly simple variations of the ligand structure affect the locus of oxidation in Cu-bis-phenoxide complexes.

  19. A survey of electronic drug information resources and identification of problems associated with the differing vocabularies used to key them.

    PubMed Central

    Gnassi, J. A.; Barnett, G. O.

    1993-01-01

    Drug information resources are increasingly becoming electronically available. They differ in scope, granularity, and purpose. These considerations have shaped the selection of dissimilar drug name keys, complicating access. An abbreviated and simplified historical context of the development of official controlled vocabularies and their relationships is followed by a review of the kinds of information available in several electronic drug information resources. The key vocabularies used are discussed with examples. Problems using the differing terms of the resource vocabularies are identified. PMID:8130551

  20. Infrastructure and resources for an aging population: embracing complexity in translational research.

    PubMed

    High, Kevin P

    2014-05-01

    The population of the United States and most industrialized nations is undergoing rapid expansion of persons aged 65 years and older. This group experiences more illness, disability, and dependency than young adults and consumes the majority of heath care resources. This demographic change presents a number of challenges to current research infrastructure aimed at translating discoveries to improved human health. Key issues include the need to expand the workforce trained in aging research, development of specific resources and harmonization of measures and outcomes, and a culture change within the scientific community. In particular, complexity must be represented within research design and embraced as an important aspect of review panel critiques.

  1. Readability, complexity, and suitability of online resources for mastectomy and lumpectomy.

    PubMed

    Tran, Bao Ngoc N; Singh, Mansher; Singhal, Dhruv; Rudd, Rima; Lee, Bernard T

    2017-05-15

    Nearly half of American adults have low or marginal health literacy. This negatively affects patients' participation, decision-making, satisfaction, and overall outcomes especially when there is a mismatch between information provided and the skills of the intended audience. Recommendations that patient information be written below the sixth grade level have been made for over three decades. This study compares online resources for mastectomy versus lumpectomy using expanded metrics including readability level, complexity, and density of data and overall suitability for public consumption. The 10 highest ranked Web sites for mastectomy and lumpectomy were identified using the largest Internet engine (Google). Each Web site was assessed for readability (Simple Measure of Gobbledygook), complexity (PMOSE/iKIRSCH), and suitability (Suitability Assessment of Materials). Scores were analyzed by each Web site and overall. Readability analysis showed a significant reading grade level difference between mastectomy and lumpectomy online information (15.4 and 13.9, P = 0.04, respectively). Complexity analysis via PMOSE/iKIRSCH revealed a mean score of 6.5 for mastectomy materials corresponding to "low" complexity and eighth to 12(th) grade education. Lumpectomy literature had a lower PMOSE/iKIRSCH score of 5.8 corresponding to a "very low" complexity and fourth to eighth grade education (P = 0.05). Suitability assessment showed mean values of 41% and 46% (P = 0.83) labeled as the lowest level of "adequacy" for mastectomy and lumpectomy materials, respectively. Inter-rater reliability was high for both complexity and suitability analysis. Online resources for the surgical treatment of breast cancer are above the recommended reading grade level. The suitability level is barely adequate indicating a need for revision. Online resources for mastectomy have a higher reading grade level than do materials for lumpectomy and tend to be more complex. Copyright © 2017 Elsevier

  2. Engineer’s Guide to the Use of Human Resources in Electronic System Design: an Evaluation.

    DTIC Science & Technology

    1980-11-01

    AD-A093 539 ANACAPA SCIENCES INC SANTA BARBARA CA F6 /5 ENGINEER’S GUIDE TO THE USE OF HUMAN RESOURCES 7N ELECTRONC ST ETC(U) 0 NOV 80 R A DICK, E A...Anacapa Sciences , Inc. in support of Navy Decision aooroinating -paper 1 -PN, subprojectZll77-PN.05, Reducing Manpower Costs Through Better System...operators and maintainers for sophisticated shipboard electronic systems. Manpower problems in operating and maintaining these systems are widely

  3. Binding sites and electronic states of group 3 metal-aniline complexes probed by high-resolution electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Kumari, Sudesh; Sohnlein, Bradford R.; Hewage, Dilrukshi; Roudjane, Mourad; Sup Lee, Jung; Yang, Dong-Sheng

    2013-06-01

    Group 3 metal-aniline complexes, M(aniline) (M = Sc, Y, and La), are produced in a pulsed laser-vaporization molecular beam source, identified by photoionization time-of-flight mass spectrometry, and investigated by pulsed-field ionization zero electron kinetic energy (ZEKE) spectroscopy and quantum chemical calculations. Adiabatic ionization energies and several low-frequency vibrational modes are measured for the first time from the ZEKE spectra. Metal binding sites and electronic states are determined by combining the ZEKE measurements with the theoretical calculations. The ionization energies of the complexes decrease down the metal group. An out-of-plane ring deformation mode coupled with an asymmetric metal-carbon stretch is considerably anharmonic. Although aniline has various possible sites for metal coordination, the preferred site is the phenyl ring. The metal binding with the phenyl ring yields syn and anti conformers with the metal atom and amino hydrogens on the same and opposite sides of the ring, respectively. The anti conformer is determined to be the spectral carrier. The ground electronic state of the anti conformer of each neutral complex is a doublet with a metal-based electron configuration of nd2(n + 1)s1, and the ground electronic state of each ion is a singlet with a metal-based electron configuration of nd2. The formation of the neutral complexes requires the nd2(n + 1)s1 ← nd1(n + 1)s2 electron excitation in the metal atoms.

  4. Electronic and steric influences of pendant amine groups on the protonation of molybdenum bis (dinitrogen) complexes

    SciTech Connect

    Labios, Liezel A.; Heiden, Zachariah M.; Mock, Michael T.

    2015-05-04

    The synthesis of a series of PEtPNRR' (PEtPNRR' = Et₂PCH₂CH₂P(CH₂NRR')₂, R = H, R' = Ph or 2,4-difluorophenyl; R = R' = Ph or iPr) diphosphine ligands containing mono- and disubstituted pendant amine groups, and the preparation of their corresponding molybdenum bis(dinitrogen) complexes trans-Mo(N₂)₂(PMePh₂)₂(PEtPNRR') is described. In situ IR and multinuclear NMR spectroscopic studies monitoring the stepwise addition of (HOTf) to trans-Mo(N₂)₂(PMePh₂)₂(PEtPNRR') complexes in THF at -40 °C show that the electronic and steric properties of the R and R' groups of the pendant amines influence whether the complexes are protonated at Mo, a pendant amine, a coordinated N2 ligand, or a combination of these sites. For example, complexes containing mono-aryl substituted pendant amines are protonated at Mo and pendant amine to generate mono- and dicationic Mo–H species. Protonation of the complex containing less basic diphenyl-substituted pendant amines exclusively generates a monocationic hydrazido (Mo(NNH₂)) product, indicating preferential protonation of an N₂ ligand. Addition of HOTf to the complex featuring more basic diisopropyl amines primarily produces a monocationic product protonated at a pendant amine site, as well as a trace amount of dicationic Mo(NNH₂) product that contain protonated pendant amines. In addition, trans-Mo(N₂)₂(PMePh₂)₂(depe) (depe = Et₂PCH₂CH₂PEt₂) without a pendant amine was synthesized and treated with HOTf, generating a monocationic Mo(NNH₂) product. Protonolysis experiments conducted on select complexes in the series afforded trace amounts of NH₄⁺. Computational analysis of the series of trans-Mo(N₂)₂(PMePh₂)₂(PEtPNRR') complexes provides further insight into the proton affinity values of the metal center, N₂ ligand, and pendant amine sites to rationalize

  5. A systematic review of portable electronic technology for health education in resource-limited settings.

    PubMed

    McHenry, Megan S; Fischer, Lydia J; Chun, Yeona; Vreeman, Rachel C

    2017-08-01

    The objective of this study is to conduct a systematic review of the literature of how portable electronic technologies with offline functionality are perceived and used to provide health education in resource-limited settings. Three reviewers evaluated articles and performed a bibliography search to identify studies describing health education delivered by portable electronic device with offline functionality in low- or middle-income countries. Data extracted included: study population; study design and type of analysis; type of technology used; method of use; setting of technology use; impact on caregivers, patients, or overall health outcomes; and reported limitations. Searches yielded 5514 unique titles. Out of 75 critically reviewed full-text articles, 10 met inclusion criteria. Study locations included Botswana, Peru, Kenya, Thailand, Nigeria, India, Ghana, and Tanzania. Topics addressed included: development of healthcare worker training modules, clinical decision support tools, patient education tools, perceptions and usability of portable electronic technology, and comparisons of technologies and/or mobile applications. Studies primarily looked at the assessment of developed educational modules on trainee health knowledge, perceptions and usability of technology, and comparisons of technologies. Overall, studies reported positive results for portable electronic device-based health education, frequently reporting increased provider/patient knowledge, improved patient outcomes in both quality of care and management, increased provider comfort level with technology, and an environment characterized by increased levels of technology-based, informal learning situations. Negative assessments included high investment costs, lack of technical support, and fear of device theft. While the research is limited, portable electronic educational resources present promising avenues to increase access to effective health education in resource-limited settings, contingent

  6. Electron Transfer Reactivity on Novel Dirhenium and Dirhodium Tetraazaannulene Complexes.

    DTIC Science & Technology

    1980-01-01

    cyclic voltammetry and differential pulse polarography. Potentials are reported for the electrochemcial generation of pi cation and pi anion radicals of these complexes in the solvents dichloromethane and dimethylformamide. The potential differences between the pi radical reactions of the metallomacrocyclic complexes were compared to the potential differences of the pi radical reactions of the free macrocycles.

  7. Molybdenum 17- and 18-electron bis- and tris(butadiene) complexes: electronic structures, spectroscopic properties, and oxidative ligand substitution reactions.

    PubMed

    Stephan, Gerald C; Näther, Christian; Peters, Gerhard; Tuczek, Felix

    2013-05-20

    New results on the electronic structures, spectroscopic properties, and reactivities of the molybdenum tris(butadiene) and tris(2,3-dimethylbutadiene) complexes [Mo(bd)3] (1(bd)) and [Mo(dmbd)3] (1(dmbd)), respectively, are reported. Importantly, the metal ligand bonding interaction can be weakened by oxidizing the metal center with ferrocenium salts. The addition of the bidentate phosphine ligand 1,2-bis(diphenylphosphino)ethane then leads to a new type of stable 17-electron complex, [Mo(dmbd)2(dppe)](X) (2; X = BF4(-), PF6(-), BPh4(-)), where one of the butadiene ligands is exchanged by a chelating phosphine. Reduction of the cationic complexes 2 generates the corresponding 18-electron complex [Mo(dmbd)2(dppe)] (3), thus establishing a new strategy for ligand substitution reactions in [Mo(bd)3] complexes via one-electron oxidized intermediates. The new heteroleptic molybdenum complexes are characterized by X-ray structure analysis; vibrational, NMR, and EPR spectroscopy; and electrochemistry. DFT calculations are performed to explain the structural and specroscopic trends observed experimentally. For compound 1(bd), a normal coordinate analysis is presented, providing additional information on the bonding situation in this type of complex.

  8. Potential resource and toxicity impacts from metals in waste electronic devices.

    PubMed

    Woo, Seung H; Lee, Dae Sung; Lim, Seong-Rin

    2016-04-01

    As a result of the continuous release of new electronic devices, existing electronic devices are quickly made obsolete and rapidly become electronic waste (e-waste). Because e-waste contains a variety of metals, information about those metals with the potential for substantial environmental impact should be provided to manufacturers, recyclers, and disposers to proactively reduce this impact. This study assesses the resource and toxicity (i.e., cancer, noncancer, and ecotoxicity) potentials of various heavy metals commonly found in e-waste from laptop computers, liquid-crystal display (LCD) monitors, LCD TVs, plasma TVs, color cathode ray tube (CRT) TVs, and cell phones and then evaluates such potentials using life cycle impact-based methods. Resource potentials derive primarily from Cu, Sb, Ag, and Pb. Toxicity potentials derive primarily from Pb, Ni, and Hg for cancer toxicity; from Pb, Hg, Zn, and As for noncancer toxicity; and from Cu, Pb, Hg, and Zn for ecotoxicity. Therefore, managing these heavy metals should be a high priority in the design, recycling, and disposal stages of electronic devices.

  9. Dismounted complex blast injuries: patterns of injuries and resource utilization associated with the multiple extremity amputee.

    PubMed

    Fleming, Mark; Waterman, Scott; Dunne, James; D'Alleyrand, Jean-Claude; Andersen, Romney C

    2012-01-01

    The objective of this report is to analyze the resource utilization and injury patterns of complex dismounted blast injuries. A retrospective review of U.S. service members injured in combat between 2007 and 2010 was conducted. Data analyzed included age, injury mechanism, amputated limbs, number and type of associated injuries, blood products utilized, intensive care unit length of stay (ILOS), hospital length of stay (HLOS) and the Injury Severity Score (ISS). Patients were stratified based on the number of amputations. Sixty-three patients comprised the multiple extremity amputation (MEA) group. Ninety-eight percent sustained injuries from an improvised explosive device (IED) and 96% were dismounted. The ISS, number of surgical encounters, blood products utilized and ILOS were all clinically significantly different than controls. Care of multiple extremity amputees involves the utilization of significant resources. This knowledge may better help surgeons and administrators allocate assets at hospitals, both military and civilian, who care for this complex and challenging patient population.

  10. Opening a Can of wERMS: Texas A&M University's Experiences in Implementing Two Electronic Resource Management Systems

    ERIC Educational Resources Information Center

    Hartnett, Eric; Price, Apryl; Smith, Jane; Barrett, Michael

    2010-01-01

    Over the past few years, Texas A&M University (TAMU) has searched for a way to administer its electronic subscriptions as well as the electronic subscriptions shared among the TAMU System. In this article, we address our attempts to implement an effective electronic resource management system (ERMS), both for subscriptions on the main campus…

  11. Electron Transfer Studies of Ruthenium(II) Complexes with Biologically Important Phenolic Acids and Tyrosine.

    PubMed

    Rajeswari, Angusamy; Ramdass, Arumugam; Muthu Mareeswaran, Paulpandian; Rajagopal, Seenivasan

    2016-03-01

    The ruthenium(II) complexes having 2,2'-bipyridine and phenanthroline derivatives are synthesized and characterized. The photophysical properties of these complexes at pH 12.5 are studied. The electron transfer reaction of biologically important phenolic acids and tyrosine are studied using absorption, emission and transient absorption spectral techniques. Semiclassical theory is applied to calculate the rate of electron transfer between ruthenium(II) complexes and biologically important phenolic acids.

  12. Electronic structure and driving forces in β-cyclodextrin: Diclofenac inclusion complexes

    NASA Astrophysics Data System (ADS)

    Bogdan, Diana; Morari, C.

    2007-07-01

    We investigate the geometry and electronic structure for complexes of β-cyclodextrin with diclofenac using DFT calculations. The effect of solvent is explicitly taken into account. This investigation allows us to draw meaningful conclusions upon the stability of the complex and the nature of the driving forces leading to the complexation process. In particular we emphasize the role of the water, by pointing out the changes in the solvent's electronic structure for different docking geometries.

  13. Redox induced electron transfer in doublet azo-anion diradical rhenium(II) complexes. Characterization of complete electron transfer series.

    PubMed

    Paul, Nandadulal; Samanta, Subhas; Goswami, Sreebrata

    2010-03-15

    Reactions of dirhenium decacarbonyl with the two azoaromatic ligands, L(a) = (2-phenylazo)pyridine and L(b) = (4-chloro-2-phenylazo)pyridine (general abbreviation of the ligands is L) afford paramagnetic rhenium(II) complexes, [Re(II)(L(*-))(2)(CO)(2)] (1) (S = 1/2 ground state) with two one-electron reduced azo-anion radical ligands in an octahedral geometrical arrangement. At room temperature (300 K) the complexes 1a-b, showed magnetic moments (mu(eff)) close to 1.94 mu(B), which is suggestive of the existence of strong antiferromagnetic interactions in the complexes. The results of magnetic measurements on one of the complexes, 1b, in the temperature range 2-300 K are reported. The above complexes showed two cathodic and two anodic responses in cyclic voltammetry where one-electron oxidation leads to an unusual redox event involving simultaneous reduction of the rhenium(II) and oxidation of the second ligand via intramolecular electron transfer. The oxidized complexes 1a(+) and 1b(+) are air stable and were isolated as crystalline solids as their tri-iodide (I(3)(-)) salts. The structures of the two representative complexes, 1b and [1b]I(3), as determined by X-ray crystallography, are compared. The anionic complexes, [1](-) and [1](2-) were characterized in solution by their spectral properties.

  14. High-resolution electron spectroscopy of lanthanide (Ce, Pr, and Nd) complexes of cyclooctatetraene: the role of 4f electrons.

    PubMed

    Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Liu, Yang; Yang, Dong-Sheng

    2013-04-28

    Cerium, praseodymium, and neodymium complexes of 1,3,5,7-cyclooctatetraene (COT) complexes were produced in a laser-vaporization metal cluster source and studied by pulsed-field ionization zero electron kinetic energy spectroscopy and quantum chemical calculations. The computations included the second-order Møller-Plesset perturbation theory, the coupled cluster method with single, double, and perturbative triple excitations, and the state-average complete active space self-consistent field method. The spectrum of each complex exhibits multiple band systems and is assigned to ionization of several low-energy electronic states of the neutral complex. This observation is different from previous studies of M(COT) (M = Sc, Y, La, and Gd), for which a single band system was observed. The presence of the multiple low-energy electronic states is caused by the splitting of the partially filled lanthanide 4f orbitals in the ligand field, and the number of the low-energy states increases rapidly with increasing number of the metal 4f electrons. On the other hand, the 4f electrons have a small effect on the geometries and vibrational frequencies of these lanthanide complexes.

  15. High-resolution electron spectroscopy of lanthanide (Ce, Pr, and Nd) complexes of cyclooctatetraene: The role of 4f electrons

    SciTech Connect

    Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Yang Dongsheng; Liu Yang

    2013-04-28

    Cerium, praseodymium, and neodymium complexes of 1,3,5,7-cyclooctatetraene (COT) complexes were produced in a laser-vaporization metal cluster source and studied by pulsed-field ionization zero electron kinetic energy spectroscopy and quantum chemical calculations. The computations included the second-order Moller-Plesset perturbation theory, the coupled cluster method with single, double, and perturbative triple excitations, and the state-average complete active space self-consistent field method. The spectrum of each complex exhibits multiple band systems and is assigned to ionization of several low-energy electronic states of the neutral complex. This observation is different from previous studies of M(COT) (M = Sc, Y, La, and Gd), for which a single band system was observed. The presence of the multiple low-energy electronic states is caused by the splitting of the partially filled lanthanide 4f orbitals in the ligand field, and the number of the low-energy states increases rapidly with increasing number of the metal 4f electrons. On the other hand, the 4f electrons have a small effect on the geometries and vibrational frequencies of these lanthanide complexes.

  16. Army Electronic Equipment Support Options: Assessment of Maintenance Complexity.

    DTIC Science & Technology

    1981-07-01

    lognormally distributed, the ratio follows from the following equation: MTTR ~ in 2-7j FIGURE 2-2. MEASURES OF MAINTENANCE COMLEXITY A OTHER FACTORS 0...tenance personnel have been noted in various studies (3). Many new systems are compute r- control led, which increases inherent complexity. Computer ...hydraulically driven turret, all controlled by a computer receiving signals from a radar set, crosses several disciplines, making the system inherently complex

  17. Mononuclear copper complex-catalyzed four-electron reduction of oxygen.

    PubMed

    Fukuzumi, Shunichi; Kotani, Hiroaki; Lucas, Heather R; Doi, Kaoru; Suenobu, Tomoyoshi; Peterson, Ryan L; Karlin, Kenneth D

    2010-05-26

    A mononuclear Cu(II) complex acts as an efficient catalyst for four-electron reduction of O(2) to H(2)O. Its reduction by a ferrocene derivative (Fc*) and reaction with O(2) leads to the formation of a peroxodicopper(II) complex; this is subsequently reduced by Fc* in the presence of protons to regenerate the Cu(II) complex.

  18. Electron Temperature Derived from Measurements of Complex Plasma Impedance

    DTIC Science & Technology

    2008-10-20

    arrangements and technique ............................................................................................ 5 IV. Experimental Results and...current versus an applied potential sweep (the probe characteristic) is a standard plasma diagnostic technique for determining electron density and...uncertainties both with respect to probe geometry, and errors associated with the fitting procedure itself. This can render fitting techniques

  19. Tuning ground states and excitations in complex electronic materials

    SciTech Connect

    Bishop, A.R.

    1996-09-01

    Modern electronic materials are characterized by a great variety of broken-symmetry ground states and excitations. Their control requires understanding and tuning underlying driving forces of spin-charge-lattice coupling, critical to macroscopic properties and applications. We report representative model calculations which demonstrate some of the richness of the phenomena and the challenges for successful microscopic modeling.

  20. Full-electron ligand-to-ligand charge transfer in a compact Re(I) complex.

    PubMed

    Yue, Yuankai; Grusenmeyer, Tod; Ma, Zheng; Zhang, Peng; Schmehl, Russell H; Beratan, David N; Rubtsov, Igor V

    2014-11-13

    Ligand-to-ligand charge transfer (LLCT) states in transition metal complexes are often characterized by fractional electron transfer due to coupling of the LLCT state with many other states via the metal. We designed and characterized a compact Re(I) complex that displays essentially full-electron charge transfer in the LLCT excited state. The complex, [Re(DCEB)(CO)3(L)](+) (DCEB = 4,4'-dicarboxyethyl-2,2'-bipyridine), referred to as ReEBA, features two redox active ligands with strong electron accepting (DCEB) and electron donating (L is 3-dimethylaminobenzonitrile (3DMABN)) properties. The lowest energy excited state formed with a ca. 10 ps time constant and was characterized as the full-electron 3DMABN → DCEB LLCT state using time-resolved infrared spectroscopy (TRIR), transient absorption spectroscopy, and DFT computations. Analysis of a range of vibrational modes helped to assign the charge transfer characteristics of the complex. The LLCT state lifetime in ReEBA shows a strong dependence on the solvent polarity and features solvent dependent frequency shifts for several vibrational reporters. The formation of a full-electron LLCT state (∼92%) was enabled by tuning the redox properties of the electron accepting ligand (DCEB) and simultaneously decoupling the redox active group of the electron donating ligand (3DMABN) from the metal center. This strategy is generally applicable for designing compact transition metal complexes that have full-electron LLCT states.

  1. [Use of internet and electronic resources among Spanish intensivist physicians. First national survey].

    PubMed

    Gómez-Tello, V; Latour-Pérez, J; Añón Elizalde, J M; Palencia-Herrejón, E; Díaz-Alersi, R; De Lucas-García, N

    2006-01-01

    Estimate knowledge and use habits of different electronic resources in a sample of Spanish intensivists: Internet, E-mail, distribution lists, and use of portable electronic devices. Self-applied questionnaire. A 50-question questionnaire was distributed among Spanish intensivists through the hospital marketing delegates of a pharmaceutical company and of electronic forums. A total of 682 questionnaires were analyzed (participation: 74%). Ninety six percent of those surveyed used Internet individually: 67% admitted training gap. Internet was the second source of clinical consultations most used (61%), slightly behind consultation to colleagues (65%). The pages consulted most were bibliographic databases (65%) and electronic professional journals (63%), with limited use of Evidence Based Medicine pages (19%). Ninety percent of those surveyed used e-mail regularly in the practice of their profession, although 25% admitted that were not aware of its possibilities. The use of E-mail decreased significantly with increase in age. A total of 62% of the intensivists used distribution lists. Of the rest, 42% were not aware of its existence and 32% admitted they had insufficient training to handle them. Twenty percent of those surveyed had portable electronic devices and 64% considered it useful, basically due to its rapid consultation at bedside. Female gender was a negative predictive factor of its use (OR 0.35; 95% CI 0.2-0.63; p=0.0002). A large majority of the Spanish intensivists use Internet and E-mail. E-mail lists and use of portable devices are still underused resources. There are important gaps in training and infrequent use of essential pages. There are specific groups that require directed educational policies.

  2. Review of material recovery from used electric and electronic equipment-alternative options for resource conservation.

    PubMed

    Friege, Henning

    2012-09-01

    For waste from electric and electronic equipment, the WEEE Directive stipulates the separate collection of electric and electronic waste. As to new electric and electronic devices, the Restriction of Hazardous Substances (RoHS) Directive bans the use of certain chemicals dangerous for man and environment. From the implementation of the WEEE directive, many unsolved problems have been documented: poor collection success, emission of dangerous substances during collection and recycling, irretrievable loss of valuable metals among others. As to RoHS, data from the literature show a satisfying success. The problems identified in the process can be reduced to some basic dilemmas at the borders between waste management, product policy and chemical safety. The objectives of the WEEE Directive and the specific targets for use and recycling of appliances are not consistent. There is no focus on scarce resources. Extended producer responsibility is not sufficient to guarantee sustainable waste management. Waste management reaches its limits due to problems of implementation but also due to physical laws. A holistic approach is necessary looking at all branch points and sinks in the stream of used products and waste from electric and electronic equipment. This may be done with respect to the general rules for sustainable management of material streams covering the three dimensions of sustainable policy. The relationships between the players in the field of electric and electronic devices have to be taken into account. Most of the problems identified in the implementation process will not be solved by the current amendment of the WEEE Directive.

  3. The cytochrome b6f complex at the crossroad of photosynthetic electron transport pathways.

    PubMed

    Tikhonov, Alexander N

    2014-08-01

    Regulation of photosynthetic electron transport at the level of the cytochrome b6f complex provides efficient performance of the chloroplast electron transport chain (ETC). In this review, after brief overview of the structural organization of the chloroplast ETC, the consideration of the problem of electron transport control is focused on the plastoquinone (PQ) turnover and its interaction with the b6f complex. The data available show that the rates of plastoquinol (PQH2) formation in PSII and its diffusion to the b6f complex do not limit the overall rate of electron transfer between photosystem II (PSII) and photosystem I (PSI). Analysis of experimental and theoretical data demonstrates that the rate-limiting step in the intersystem chain of electron transport is determined by PQH2 oxidation at the Qo-site of the b6f complex, which is accompanied by the proton release into the thylakoid lumen. The acidification of the lumen causes deceleration of PQH2 oxidation, thus impeding the intersystem electron transport. Two other mechanisms of regulation of the intersystem electron transport have been considered: (i) "state transitions" associated with the light-induced redistribution of solar energy between PSI and PSII, and (ii) redistribution of electron fluxes between alternative pathways (noncyclic electron transport and cyclic electron flow around PSI). Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  4. An x-ray photoemission electron microscope using an electron mirror aberration corrector for the study of complex materials

    NASA Astrophysics Data System (ADS)

    Feng, J.; Forest, E.; MacDowell, A. A.; Marcus, M.; Padmore, H.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stöhr, J.; Wan, W.; Wei, D. H.; Wu, Y.

    2005-04-01

    A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed at the advanced light source (ALS). An electron mirror combined with a sophisticated magnetic beam separator is used to provide simultaneous correction of spherical and chromatic aberrations. Installed on an elliptically polarized undulator beamline, PEEM3 will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials.

  5. Photochemistry between a ruthenium(II) pyridylimidazole complex and benzoquinone: simple electron transfer versus proton-coupled electron transfer.

    PubMed

    Hönes, Roland; Kuss-Petermann, Martin; Wenger, Oliver S

    2013-02-01

    A ruthenium(II) complex with two 4,4'-bis(trifluoromethyl)-2,2'-bipyridine chelates and a 2-(2'-pyridyl)imidazole ligand was synthesized and characterized by electrochemical and optical spectroscopic means. The respective complex has the potential to act as a combined electron-proton donor when promoted to its long-lived (3)MLCT excited state with visible light. The possibility of proton-coupled electron transfer (PCET) between the ruthenium(II) complex and 1,4-benzoquinone as an electron/proton acceptor was explored by steady-state and time-resolved luminescence spectroscopy, as well as by transient absorption spectroscopy in the nanosecond time regime. Excited-state deactivation is found to occur predominantly via simple oxidative quenching involving no proton motion, but a minor fraction of the photoexcited complex appears to react via PCET since there is spectral evidence for semiquinone as a photoproduct. Presumably, PCET is not kinetically competitive with simple electron transfer because the latter process is sufficiently exergonic and because there is little thermodynamic benefit from coupling proton transfer to the photoinduced electron transfer.

  6. New trends in the optical and electronic applications of polymers containing transition-metal complexes.

    PubMed

    Liu, Shu-Juan; Chen, Yang; Xu, Wen-Juan; Zhao, Qiang; Huang, Wei

    2012-04-13

    Polymers containing transition-metal complexes exhibit excellent optical and electronic properties, which are different from those of polymers with a pure organic skeleton and combine the advantages of both polymers and metal complexes. Hence, research about this class of polymers has attracted more and more interest in recent years. Up to now, a number of novel polymers containing transition-metal complexes have been exploited, and significant advances in their optical and electronic applications have been achieved. In this article, we summarize some new research trends in the applications of this important class of optoelectronic polymers, such as chemo/biosensors, electronic memory devices and photovoltaic devices.

  7. Evolving complex dynamics in electronic models of genetic networks

    NASA Astrophysics Data System (ADS)

    Mason, Jonathan; Linsay, Paul S.; Collins, J. J.; Glass, Leon

    2004-09-01

    Ordinary differential equations are often used to model the dynamics and interactions in genetic networks. In one particularly simple class of models, the model genes control the production rates of products of other genes by a logical function, resulting in piecewise linear differential equations. In this article, we construct and analyze an electronic circuit that models this class of piecewise linear equations. This circuit combines CMOS logic and RC circuits to model the logical control of the increase and decay of protein concentrations in genetic networks. We use these electronic networks to study the evolution of limit cycle dynamics. By mutating the truth tables giving the logical functions for these networks, we evolve the networks to obtain limit cycle oscillations of desired period. We also investigate the fitness landscapes of our networks to determine the optimal mutation rate for evolution.

  8. Electronic spectroscopy of I2-Xe complexes in solid Krypton

    NASA Astrophysics Data System (ADS)

    Hulkko, Eero; Ahokas, Jussi; Lindgren, Johan; Myllyperkiö, Pasi; Pettersson, Mika

    2012-05-01

    In the present work, we have studied ion-pair states of matrix-isolated I2 with vacuum-UV absorption and UV-vis-NIR emission, where the matrix environment is systematically changed by mixing Kr with Xe, from pure Kr to a more polarizable Xe host. Particular emphasis is put on low doping levels of Xe that yield a binary complex I2-Xe, as verified by coherent anti-Stokes Raman scattering (CARS) measurements. Associated with interaction of I2 with Xe we can observe strong new absorption in vacuum-UV, redshifted 2400 cm-1 from the X → D transition of I2. Observed redshift can be explained by symmetry breaking of ion-pair states within the I2-Xe complex. Systematic Xe doping of Kr matrices shows that at low doping levels, positions of I2 ion-pair emissions are not significantly affected by complexation with Xe, but simultaneous increase of emissions from doubly spin-excited states indicates non-radiative relaxation to valence states. At intermediate doping levels ion-pair emissions shift systematically to red due to change in the average polarizability of the environment. We have conducted spectrally resolved ultrafast pump-probe ion-pair emission studies with pure and Xe doped Kr matrices, in order to reveal the influence of Xe to I2 dynamics in solid Kr. Strikingly, relaxed emission from the ion-pair states shows no indication of complex presence. It further indicates that the complex escapes detection due to a non-radiative relaxation.

  9. Counter-ligand control of the electronic structure in dinuclear copper-tetrakisguanidine complexes.

    PubMed

    Ziesak, Alexandra; Wesp, Tobias; Hübner, Olaf; Kaifer, Elisabeth; Wadepohl, Hubert; Himmel, Hans-Jörg

    2015-11-28

    The redox-active GFA (Guanidino-Functionalized Aromatic compound) 1,4,5,8-tetrakis(tetramethylguanidino)-naphthalene (6) is used to synthesize new dinuclear copper complexes of the formula [6(CuX2)2] with different electronic structures. With X = OAc, a dinuclear Cu(II) complex of the neutral GFA is obtained (electronic structure [Cu(II)-GFA-Cu(II)], two unpaired electrons), and with X = Br a diamagnetic dinuclear Cu(I) complex of the dicationic GFA (electronic structure [Cu(I)-GFA(2+)-Cu(I)], closed-shell singlet state). The different electronic structures lead to significant differences in the optical, structural and magnetic properties of the complexes. Furthermore, the complex [6(CuI)2](2+) (electronic structure [Cu(I)-GFA(2+)-Cu(I)], closed-shell singlet state) is synthesized by reaction of 6(2+) with two equivalents of CuI. Slow decomposition of this complex in solution leads to the fluorescent dye 2,7-bis(dimethylamino)-1,3,6,8-tetraazapyrene. In an improved synthesis of this tetraazapyrene, 6 is reacted with CuBr in the presence of dioxygen. Quantum chemical calculations show that the addition of counter-ligands to the trigonal planar Cu(I) atoms of [6(CuI)2](2+) favors or disfavors one of the electronic structures, depending on the nature of the counter-ligand.

  10. Determining the level of awareness of the physicians in using the variety of electronic information resources and the effecting factors

    PubMed Central

    Papi, Ahmad; Ghazavi, Roghayeh; Moradi, Salimeh

    2015-01-01

    Background: Understanding of the medical society's from the types of information resources for quick and easy access to information is an imperative task in medical researches and management of the treatment. The present study was aimed to determine the level of awareness of the physicians in using various electronic information resources and the factors affecting it. Materials and Methods: This study was a descriptive survey. The data collection tool was a researcher-made questionnaire. The study population included all the physicians and specialty physicians of the teaching hospitals affiliated to Isfahan University of Medical Sciences and numbered 350. The sample size based on Morgan's formula was set at 180. The content validity of the tool was confirmed by the library and information professionals and the reliability was 95%. Descriptive statistics were used including the SPSS software version 19. Results: On reviewing the need of the physicians to obtain the information on several occasions, the need for information in conducting the researches was reported by the maximum number of physicians (91.9%) and the usage of information resources, especially the electronic resources, formed 65.4% as the highest rate with regard to meeting the information needs of the physicians. Among the electronic information databases, the maximum awareness was related to Medline with 86.5%. Among the various electronic information resources, the highest awareness (43.3%) was related to the E-journals. The highest usage (36%) was also from the same source. The studied physicians considered the most effective deterrent in the use of electronic information resources as being too busy and lack of time. Conclusion: Despite the importance of electronic information resources for the physician's community, there was no comprehensive knowledge of these resources. This can lead to less usage of these resources. Therefore, careful planning is necessary in the hospital libraries in order to

  11. A preliminary categorization of end-of-life electrical and electronic equipment as secondary metal resources

    SciTech Connect

    Oguchi, Masahiro; Murakami, Shinsuke; Sakanakura, Hirofumi; Kida, Akiko; Kameya, Takashi

    2011-09-15

    Highlights: > End-of-life electrical and electronic equipment (EEE) as secondary metal resources. > The content and the total amount of metals in specific equipment are both important. > We categorized 21 EEE types from contents and total amounts of various metals. > Important equipment types as secondary resources were listed for each metal kind. > Collectability and possible collection systems of various EEE types were discussed. - Abstract: End-of-life electrical and electronic equipment (EEE) has recently received attention as a secondary source of metals. This study examined characteristics of end-of-life EEE as secondary metal resources to consider efficient collection and metal recovery systems according to the specific metals and types of EEE. We constructed an analogy between natural resource development and metal recovery from end-of-life EEE and found that metal content and total annual amount of metal contained in each type of end-of-life EEE should be considered in secondary resource development, as well as the collectability of the end-of-life products. We then categorized 21 EEE types into five groups and discussed their potential as secondary metal resources. Refrigerators, washing machines, air conditioners, and CRT TVs were evaluated as the most important sources of common metals, and personal computers, mobile phones, and video games were evaluated as the most important sources of precious metals. Several types of small digital equipment were also identified as important sources of precious metals; however, mid-size information and communication technology (ICT) equipment (e.g., printers and fax machines) and audio/video equipment were shown to be more important as a source of a variety of less common metals. The physical collectability of each type of EEE was roughly characterized by unit size and number of end-of-life products generated annually. Current collection systems in Japan were examined and potentially appropriate collection methods

  12. Success criteria for electronic medical record implementations in low-resource settings: a systematic review.

    PubMed

    Fritz, Fleur; Tilahun, Binyam; Dugas, Martin

    2015-03-01

    Electronic medical record (EMR) systems have the potential of supporting clinical work by providing the right information at the right time to the right people and thus make efficient use of resources. This is especially important in low-resource settings where reliable data are also needed to support public health and local supporting organizations. In this systematic literature review, our objectives are to identify and collect literature about success criteria of EMR implementations in low-resource settings and to summarize them into recommendations. Our search strategy relied on PubMed queries and manual bibliography reviews. Studies were included if EMR implementations in low-resource settings were described. The extracted success criteria and measurements were summarized into 7 categories: ethical, financial, functionality, organizational, political, technical, and training. We collected 381 success criteria with 229 measurements from 47 articles out of 223 articles. Most papers were evaluations or lessons learned from African countries, published from 1999 to 2013. Almost half of the EMR systems served a specific disease area like human immunodeficiency virus (HIV). The majority of criteria that were reported dealt with the functionality, followed by organizational issues, and technical infrastructures. Sufficient training and skilled personnel were mentioned in roughly 10%. Political, ethical, and financial considerations did not play a predominant role. More evaluations based on reliable frameworks are needed. Highly reliable data handling methods, human resources and effective project management, as well as technical architecture and infrastructure are all key factors for successful EMR implementation. © The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. Impact of Knowledge Resources Linked to an Electronic Health Record on Frequency of Unnecessary Tests and Treatments

    ERIC Educational Resources Information Center

    Goodman, Kenneth; Grad, Roland; Pluye, Pierre; Nowacki, Amy; Hickner, John

    2012-01-01

    Introduction: Electronic knowledge resources have the potential to rapidly provide answers to clinicians' questions. We sought to determine clinicians' reasons for searching these resources, the rate of finding relevant information, and the perceived clinical impact of the information they retrieved. Methods: We asked general internists, family…

  14. Impact of Knowledge Resources Linked to an Electronic Health Record on Frequency of Unnecessary Tests and Treatments

    ERIC Educational Resources Information Center

    Goodman, Kenneth; Grad, Roland; Pluye, Pierre; Nowacki, Amy; Hickner, John

    2012-01-01

    Introduction: Electronic knowledge resources have the potential to rapidly provide answers to clinicians' questions. We sought to determine clinicians' reasons for searching these resources, the rate of finding relevant information, and the perceived clinical impact of the information they retrieved. Methods: We asked general internists, family…

  15. Effect of pressure on electronic excitations in TCNQ and its complexes

    SciTech Connect

    Tkacz, M.; Jurgensen, C.W.; Drickamer, H.G.

    1986-01-15

    The electronic spectra of TCNQ and TCNQ complexes has been investigated at high pressure up to 150 kbar. The observed pressure shifts are discussed in terms of intermolecular interactions. The results are also compared with available theoretical calculations.

  16. Progression in Complexity: Contextualizing Sustainable Marine Resources Management in a 10th Grade Classroom

    NASA Astrophysics Data System (ADS)

    Bravo-Torija, Beatriz; Jiménez-Aleixandre, María-Pilar

    2012-01-01

    Sustainable management of marine resources raises great challenges. Working with this socio-scientific issue in the classroom requires students to apply complex models about energy flow and trophic pyramids in order to understand that food chains represent transfer of energy, to construct meanings for sustainable resources management through discourse, and to connect them to actions and decisions in a real-life context. In this paper we examine the process of elaboration of plans for resources management in a marine ecosystem by 10th grade students (15-16 year) in the context of solving an authentic task. A complete class ( N = 14) worked in a sequence about ecosystems. Working in small groups, the students made models of energy flow and trophic pyramids, and used them to solve the problem of feeding a small community for a long time. Data collection included videotaping and audiotaping of all of the sessions, and collecting the students' written productions. The research objective is to examine the process of designing a plan for sustainable resources management in terms of the discursive moves of the students across stages in contextualizing practices, or different degrees of complexity (Jiménez-Aleixandre & Reigosa International Journal of Science Education, 14(1): 51-61 2006), understood as transformations from theoretical statements to decisions about the plan. The analysis of students' discursive moves shows how the groups progressed through stages of connecting different models, between them and with the context, in order to solve the task. The challenges related to taking this sustainability issue to the classroom are discussed.

  17. Complex housing environment for farmed blue foxes (Vulpes lagopus): use of various resources.

    PubMed

    Koistinen, T; Korhonen, H T

    2013-08-01

    The present study was designed to measure the use of various, simultaneously available resources in a complex housing environment in juvenile blue foxes. Twelve blue fox sibling (male-female) pairs were housed in two-section experimental cages from the age of 8 weeks until the age of 7 months (from June to December). Each experimental cage was furnished with two platforms, a nest box, a sand box and a wooden block. This housing set-up provided the foxes with social contact, and an opportunity for oral manipulation, scratching and nesting, as well as the choice of staying on a solid floor material or on an elevated location. The foxes' behaviour was recorded at three time points during autumn (September, November and December). The foxes used all available resources. The most utilised resource was the nest box, possibly because it could be utilised in several ways (as a shelter, an elevated location, an object for scratching and for oral manipulation). The foxes also stayed more in the cage section containing the nest box than in the cage section containing a sand box. The foxes rested much on the cage floor, but they also used the interior of the nest box and elevated locations for resting. Social contact often occurred during resting. Thus, the nest box and elevated location, in conjunction with social contact seem to be valuable while resting. While active, the foxes utilised the cage floor and roof of the nest box instead of the platforms. Scratching, digging and an interaction with the wooden block were seldom observed. Activity occurred mainly on the 'empty' cage area. In conclusion, all studied resources provided blue foxes with a distinct value, as they all were used in the complex housing environment. The nest box is used most and for most variable behaviours.

  18. Towards Intelligent Dynamic Deployment of Mobile Sensors in Complex Resource-Bounded Environments

    SciTech Connect

    Ng, B M; Hanley, W G

    2007-05-08

    Decision-making in the face of uncertainty requires an understanding of the probabilistic mechanisms that govern the complex behavior of these systems. This issue applies to many domains: financial investments, disease control, military planning and homeland security. In each of these areas, there is a practical need for efficient resource-bounded reasoning capabilities to support optimal decision-making. Specifically, given a highly complex system, with numerous random variables and their dynamic interactions, how do we monitor such a system and detect crucial events that might impact our decision making process? More importantly, how do we perform this reasoning efficiently--to an acceptable degree of accuracy in real time--when there are only limited computational power and sensory capabilities? These questions encapsulate nontrivial key issues faced by many high-profile Laboratory missions: the problem of efficient inference and dynamic sensor deployment for risk/uncertainty reduction. By leveraging solid ideas such as system decomposition into loosely coupled subsystems and smart resource allocation among these subsystems, we can parallelize inference and data acquisition for faster and improved computational performance. In this report, we propose technical approaches for developing algorithmic tools to enable future scientific and engineering endeavors to better achieve the optimal use of limited resources for maximal return of information on a complex system. The result of the proposed research effort will be an efficient reasoning framework that would enable mobile sensors to work collaboratively as teams of adaptive and responsive agents, whose joint goal is to gather useful information that would assist in the inference process.

  19. Contact effects on electronic transport in donor-bridge-acceptor complexes interacting with a thermal bath.

    PubMed

    Volkovich, Roie; Peskin, Uri

    2006-12-28

    A model for electron transfer in donor-bridge-acceptor complexes with electronic coupling to nuclear bridge modes is studied using the Redfield formulation. We demonstrate that the transport mechanism through the molecular bridge is controlled by the location of the electronic-nuclear coupling term along the bridge. As the electronic-nuclear coupling term is shifted from the donor/acceptor-bridge contact sites into the bridge, the mechanism changes from kinetic transport (incoherent, thermally activated, and bridge-length independent) to coherent tunneling oscillations. This study joins earlier works aiming to explore the factors which control the mechanism of electronic transport through molecular bridges and molecular wires.

  20. Gd(III) complexes for electron-electron dipolar spectroscopy: Effects of deuteration, pH and zero field splitting

    NASA Astrophysics Data System (ADS)

    Garbuio, Luca; Zimmermann, Kaspar; Häussinger, Daniel; Yulikov, Maxim

    2015-10-01

    Spectral parameters of Gd(III) complexes are intimately linked to the performance of the Gd(III)-nitroxide or Gd(III)-Gd(III) double electron-electron resonance (DEER or PELDOR) techniques, as well as to that of relaxation induced dipolar modulation enhancement (RIDME) spectroscopy with Gd(III) ions. These techniques are of interest for applications in structural biology, since they can selectively detect site-to-site distances in biomolecules or biomolecular complexes in the nanometer range. Here we report relaxation properties, echo detected EPR spectra, as well as the magnitude of the echo reduction effect in Gd(III)-nitroxide DEER for a series of Gadolinium(III) complexes with chelating agents derived from tetraazacyclododecane. We observed that solvent deuteration does not only lengthen the relaxation times of Gd(III) centers but also weakens the DEER echo reduction effect. Both of these phenomena lead to an improved signal-to-noise ratios or, alternatively, longer accessible distance range in pulse EPR measurements. The presented data enrich the knowledge on paramagnetic Gd(III) chelate complexes in frozen solutions, and can help optimize the experimental conditions for most types of the pulse measurements of the electron-electron dipolar interactions.

  1. Protein–Protein Interaction Regulates the Direction of Catalysis and Electron Transfer in a Redox Enzyme Complex

    SciTech Connect

    McMillan, Duncan G. G.; Marritt, Sophie J.; Firer-Sherwood, Mackenzie A.; Shi, Liang; Richardson, David J.; Evans, Stephen D.; Elliott, Sean J.; Butt, Julea N.; Jeuken, Lars J. C.

    2013-07-17

    Protein-protein complexes are fundamental to life where they are key to processes ranging from central metabolism to cell signaling. Transient protein-protein interactions generally underpin the electron-transfer (ET) pathways of respiration.1 One of the many well-characterized examples of a transient ET complex is that between cytochrome c and cytochrome c oxidase.2-5 The interaction between these partner proteins is weak and dynamic. This ensures the frequent exchange of partner proteins as required to support electron flux in cases where the sole function of one of the proteins is to shuttle electrons between redox partners.1 While it is generally assumed that such transient protein-protein interactions are specific, for Paracoccus denitrificans it has recently been shown that seven proteins in a respiratory network interact in a seemingly ill-defined manner. This results in an intricate electron-transfer network that may be better suited to successful colonization of habitats with changing resources.

  2. Virtual enterprise model for the electronic components business in the Nuclear Weapons Complex

    SciTech Connect

    Ferguson, T.J.; Long, K.S.; Sayre, J.A.; Hull, A.L.; Carey, D.A.; Sim, J.R.; Smith, M.G.

    1994-08-01

    The electronic components business within the Nuclear Weapons Complex spans organizational and Department of Energy contractor boundaries. An assessment of the current processes indicates a need for fundamentally changing the way electronic components are developed, procured, and manufactured. A model is provided based on a virtual enterprise that recognizes distinctive competencies within the Nuclear Weapons Complex and at the vendors. The model incorporates changes that reduce component delivery cycle time and improve cost effectiveness while delivering components of the appropriate quality.

  3. Influence of electronic structure of diamines on ability to form complexes

    SciTech Connect

    Bresler, I.G.; Fatkullina, F.A.; Akhunov, T.F.; Kantor, E.A.; Rakhmankulov, D.L.

    1986-05-01

    To study, the influence of substituents in tetraalkylmethylenediamines on their electron-donor capacity, they studied complexes of molecular iodine with molecules of tetramethyl-methylenediamine (TMMDA) and tetraethylmethylenediamine (TEMDA) in an n-heptane medium at 22/sup 0/C according to electronic absorption spectra. The experiments show that an addition of TMMDA and TEMDA to an iodine solution in n-heptane leads to the formation of charge transfer complexes.

  4. U.S. Geological Survey Groundwater Modeling Software: Making Sense of a Complex Natural Resource

    USGS Publications Warehouse

    Provost, Alden M.; Reilly, Thomas E.; Harbaugh, Arlen W.; Pollock, David W.

    2009-01-01

    Computer models of groundwater systems simulate the flow of groundwater, including water levels, and the transport of chemical constituents and thermal energy. Groundwater models afford hydrologists a framework on which to organize their knowledge and understanding of groundwater systems, and they provide insights water-resources managers need to plan effectively for future water demands. Building on decades of experience, the U.S. Geological Survey (USGS) continues to lead in the development and application of computer software that allows groundwater models to address scientific and management questions of increasing complexity.

  5. Observation of Electronic Excitation Transfer Through Light Harvesting Complex II Using Two-Dimensional Electronic-Vibrational Spectroscopy

    SciTech Connect

    Lewis, Nicholas H. C.; Gruenke, Natalie L.; Oliver, Thomas A. A.; Ballottari, Matteo; Bassi, Roberto; Fleming, Graham R.

    2016-10-05

    Light-harvesting complex II (LHCII) serves a central role in light harvesting for oxygenic photosynthesis and is arguably the most important photosynthetic antenna complex. In this article, we present two-dimensional electronic–vibrational (2DEV) spectra of LHCII isolated from spinach, demonstrating the possibility of using this technique to track the transfer of electronic excitation energy between specific pigments within the complex. We assign the spectral bands via comparison with the 2DEV spectra of the isolated chromophores, chlorophyll a and b, and present evidence that excitation energy between the pigments of the complex are observed in these spectra. Lastly, we analyze the essential components of the 2DEV spectra using singular value decomposition, which makes it possible to reveal the relaxation pathways within this complex.

  6. Electronic interactions in metal complexed photoconducting polymers : a ZINDO study.

    SciTech Connect

    Manas, E. S.; Chen, L. X.; Chemistry; Univ. of Pennsylvania School of Medicine

    2000-12-01

    Semi-empirical (INDO/s) calculations have been conducted on molecular fragments with zero to three phenylenevinylene (PV) units attached to 4 and 4{prime} positions of a 2,2{prime}-bipyridine (bpy) group, with and without chelated metal ions, mimicking metal-free and metal-chelated photoconducting polymers 1 and 2 [Chen et al., J. Phys. Chem. B 104 (2000) 1950]. The calculations suggest that: (1) a global lowering of the molecular orbital energy levels due to metal-chelation is responsible for the observed red-shift in the lowest energy transitions; and (2) metal chelation attenuates {pi}-electron delocalization. The relevance of these effects to photoluminescence of metal-chelated polymers is also discussed.

  7. Fluctuation electron microscopy studies of complex structured materials

    NASA Astrophysics Data System (ADS)

    Zhao, Gongpu; Rougée, Annick; Buseck, Peter; Treacy, Michael

    2008-03-01

    Fluctuation electron microscopy (FEM) is a hybrid imaging-diffraction technique. This technique is particularly sensitive to paracrystalline structures of dimension 0.5-2 nm, which are difficult to detect by either imaging or diffraction techniques alone. It has been successfully deployed to study paracrystalline structures in amorphous silicon, germanium thin film. This technique has also been used to study metallic glasses and oxide glasses. Until now, FEM has not been used to study disordered geological materials. In this talk we present our FEM studies of shungite, a naturally occurring disordered carbonaceous material, reveal that trace quantities of tightly curved graphene structures such as C60, or fragments of C60, is present in shungite. We also present results from our study of metamict zircon, whose crystal structure is destroyed by self-radiation during naturally occurring α decay events. Work is in progress to study the structural evolution during the metamictization process.

  8. Complex structure of triangular graphene: electronic, magnetic and electromechanical properties.

    PubMed

    Ezawa, Motohiko

    2012-01-01

    We have investigated electronic and magnetic properties of graphene nanodisks (nanosize triangular graphene) as well as electromechanical properties of graphene nanojunctions. Nanodisks are nanomagnets made of graphene, which are robust against perturbation such as impurities and lattice defects, where the ferromagnetic order is assured by Lieb's theorem. We can generate a spin current by spin filter, and manipulate it by a spin valve, a spin switch and other spintronic devices made of graphene nanodisks. We have analyzed nanodisk arrays, which have multi-degenerate perfect flat bands and are ferromagnet. By connecting two triangular graphene corners, we propose a nanomechanical switch and rotator, which can detect a tiny angle rotation by measuring currents between the two corners. By making use of the strain induced Peierls transition of zigzag nanoribbons, we also propose a nanomechanical stretch sensor, in which the conductance can be switched off by a nanometer scale stretching.

  9. Unveiling the complex electronic structure of amorphous metal oxides

    PubMed Central

    Århammar, C.; Pietzsch, Annette; Bock, Nicolas; Holmström, Erik; Araujo, C. Moyses; Gråsjö, Johan; Zhao, Shuxi; Green, Sara; Peery, T.; Hennies, Franz; Amerioun, Shahrad; Föhlisch, Alexander; Schlappa, Justine; Schmitt, Thorsten; Strocov, Vladimir N.; Niklasson, Gunnar A.; Wallace, Duane C.; Rubensson, Jan-Erik; Johansson, Börje; Ahuja, Rajeev

    2011-01-01

    Amorphous materials represent a large and important emerging area of material’s science. Amorphous oxides are key technological oxides in applications such as a gate dielectric in Complementary metal-oxide semiconductor devices and in Silicon-Oxide-Nitride-Oxide-Silicon and TANOS (TaN-Al2O3-Si3N4-SiO2-Silicon) flash memories. These technologies are required for the high packing density of today’s integrated circuits. Therefore the investigation of defect states in these structures is crucial. In this work we present X-ray synchrotron measurements, with an energy resolution which is about 5–10 times higher than is attainable with standard spectrometers, of amorphous alumina. We demonstrate that our experimental results are in agreement with calculated spectra of amorphous alumina which we have generated by stochastic quenching. This first principles method, which we have recently developed, is found to be superior to molecular dynamics in simulating the rapid gas to solid transition that takes place as this material is deposited for thin film applications. We detect and analyze in detail states in the band gap that originate from oxygen pairs. Similar states were previously found in amorphous alumina by other spectroscopic methods and were assigned to oxygen vacancies claimed to act mutually as electron and hole traps. The oxygen pairs which we probe in this work act as hole traps only and will influence the information retention in electronic devices. In amorphous silica oxygen pairs have already been found, thus they may be a feature which is characteristic also of other amorphous metal oxides.

  10. Application of models for exchange of electronic documents in complex administrative services

    SciTech Connect

    Glavev, Victor

    2015-11-30

    The report presents application of models for exchange of electronic documents between different administrations in government and business sectors. It shows the benefits of implementing electronic exchange of documents between different local offices of one administration in government sector such as a municipality and the way it is useful for implementing complex administrative services.

  11. Application of models for exchange of electronic documents in complex administrative services

    NASA Astrophysics Data System (ADS)

    Glavev, Victor

    2015-11-01

    The report presents application of models for exchange of electronic documents between different administrations in government and business sectors. It shows the benefits of implementing electronic exchange of documents between different local offices of one administration in government sector such as a municipality and the way it is useful for implementing complex administrative services.

  12. Electron spin resonance of radicals and metal complexes

    NASA Astrophysics Data System (ADS)

    The materials are a collection of extended synopsis of papers presented at the conference sessions. The broad area of magnetic technique applications has been described as well as their spectra interpretation methods. The ESR, NMR, ENDOR, and spin echo were applied for studying the radiation and UV induced radicals in chemical and biological systems. Also in the study of complexes of metallic ions (having the paramagnetic properties) and their interaction with the matrix, the magnetic techniques have been commonly used. They are also very convenient tool for the study of reaction kinetics and mechanism as well as interaction of paramagnetic species with themselves and crystal lattice or with the surface as for the catalytic processes.

  13. Western Mineral and Environmental Resources Science Center--providing comprehensive earth science for complex societal issues

    USGS Publications Warehouse

    Frank, David G.; Wallace, Alan R.; Schneider, Jill L.

    2010-01-01

    supports approximately 40 USGS research specialists who utilize cooperative agreements with universities, industry, and other governmental agencies to support their collaborative research and information exchange. Scientists of the WMERSC study how and where non-fuel mineral resources form and are concentrated in the earth's crust, where mineral resources might be found in the future, and how mineral materials interact with the environment to affect human and ecosystem health. Natural systems (ecosystems) are complex - our understanding of how ecosystems operate requires collecting and synthesizing large amounts of geologic, geochemical, biologic, hydrologic, and meteorological information. Scientists in the Center strive to understand the interplay of various processes and how they affect the structure, composition, and health of ecosystems. Such understanding, which is then summarized in publicly available reports, is used to address and solve a wide variety of issues that are important to society and the economy. WMERSC scientists have extensive national and international experience in these scientific specialties and capabilities - they have collaborated with many Federal, State, and local agencies; with various private sector organizations; as well as with foreign countries and organizations. Nearly every scientific and societal challenge requires a different combination of scientific skills and capabilities. With their breadth of scientific specialties and capabilities, the scientists of the WMERSC can provide scientifically sound approaches to a wide range of societal challenges and issues. The following sections describe examples of important issues that have been addressed by scientists in the Center, the methods employed, and the relevant conclusions. New directions are inevitable as societal needs change over time. Scientists of the WMERSC have a diverse set of skills and capabilities and are proficient in the collection and integration of

  14. Making the Right Connections: Perceptions of Human Resource/Personnel Directors Concerning Electronic Job-Search Methods.

    ERIC Educational Resources Information Center

    Hubbard, Joan C.; North, Alexa B.; Arjomand, H. Lari

    1997-01-01

    Examines methods used to search for entry-level managerial positions and assesses how human resource and personnel directors in Georgia perceive these methods. Findings indicate that few of the directors use electronic technology to fill such positions, but they view positively those applicants who use electronic job searching methods. (RJM)

  15. Control of electron transport routes through redox-regulated redistribution of respiratory complexes

    PubMed Central

    Liu, Lu-Ning; Bryan, Samantha J.; Huang, Fang; Yu, Jianfeng; Nixon, Peter J.; Rich, Peter R.; Mullineaux, Conrad W.

    2012-01-01

    In cyanobacteria, respiratory electron transport takes place in close proximity to photosynthetic electron transport, because the complexes required for both processes are located within the thylakoid membranes. The balance of electron transport routes is crucial for cell physiology, yet the factors that control the predominance of particular pathways are poorly understood. Here we use a combination of tagging with green fluorescent protein and confocal fluorescence microscopy in live cells of the cyanobacterium Synechococcus elongatus PCC 7942 to investigate the distribution on submicron scales of two key respiratory electron donors, type-I NAD(P)H dehydrogenase (NDH-1) and succinate dehydrogenase (SDH). When cells are grown under low light, both complexes are concentrated in discrete patches in the thylakoid membranes, about 100–300 nm in diameter and containing tens to hundreds of complexes. Exposure to moderate light leads to redistribution of both NDH-1 and SDH such that they become evenly distributed within the thylakoid membranes. The effects of electron transport inhibitors indicate that redistribution of respiratory complexes is triggered by changes in the redox state of an electron carrier close to plastoquinone. Redistribution does not depend on de novo protein synthesis, and it is accompanied by a major increase in the probability that respiratory electrons are transferred to photosystem I rather than to a terminal oxidase. These results indicate that the distribution of complexes on the scale of 100–300 nm controls the partitioning of reducing power and that redistribution of electron transport complexes on these scales is a physiological mechanism to regulate the pathways of electron flow. PMID:22733774

  16. Electronic theses and dissertations: a review of this valuable resource for nurse scholars worldwide.

    PubMed

    Goodfellow, L M

    2009-06-01

    A worldwide repository of electronic theses and dissertations (ETDs) could provide worldwide access to the most up-to-date research generated by masters and doctoral students. Until that international repository is established, it is possible to access some of these valuable knowledge resources. ETDs provide a technologically advanced medium with endless multimedia capabilities that far exceed the print and bound copies of theses and dissertations housed traditionally in individual university libraries. CURRENT USE: A growing trend exists for universities worldwide to require graduate students to submit theses or dissertations as electronic documents. However, nurse scholars underutilize ETDs, as evidenced by perusing bibliographic citation lists in many of the research journals. ETDs can be searched for and retrieved through several digital resources such as the Networked Digital Library of Theses and Dissertations (http://www.ndltd.org), ProQuest Dissertations and Theses (http://www.umi.com), the Australasian Digital Theses Program (http://adt.caul.edu.au/) and through individual university web sites and online catalogues. An international repository of ETDs benefits the community of nurse scholars in many ways. The ability to access recent graduate students' research electronically from anywhere in the world is advantageous. For scholars residing in developing countries, access to these ETDs may prove to be even more valuable. In some cases, ETDs are not available for worldwide access and can only be accessed through the university library from which the student graduated. Public access to university library ETD collections is not always permitted. Nurse scholars from both developing and developed countries could benefit from ETDs.

  17. Data Mining Approaches for Modeling Complex Electronic Circuit Design Activities

    SciTech Connect

    Kwon, Yongjin; Omitaomu, Olufemi A; Wang, Gi-Nam

    2008-01-01

    A printed circuit board (PCB) is an essential part of modern electronic circuits. It is made of a flat panel of insulating materials with patterned copper foils that act as electric pathways for various components such as ICs, diodes, capacitors, resistors, and coils. The size of PCBs has been shrinking over the years, while the number of components mounted on these boards has increased considerably. This trend makes the design and fabrication of PCBs ever more difficult. At the beginning of design cycles, it is important to estimate the time to complete the steps required accurately, based on many factors such as the required parts, approximate board size and shape, and a rough sketch of schematics. Current approach uses multiple linear regression (MLR) technique for time and cost estimations. However, the need for accurate predictive models continues to grow as the technology becomes more advanced. In this paper, we analyze a large volume of historical PCB design data, extract some important variables, and develop predictive models based on the extracted variables using a data mining approach. The data mining approach uses an adaptive support vector regression (ASVR) technique; the benchmark model used is the MLR technique currently being used in the industry. The strengths of SVR for this data include its ability to represent data in high-dimensional space through kernel functions. The computational results show that a data mining approach is a better prediction technique for this data. Our approach reduces computation time and enhances the practical applications of the SVR technique.

  18. Knowledge and use of electronic information resources by medical sciences faculty at The University of the West Indies

    PubMed Central

    Renwick, Shamin

    2005-01-01

    Objective: The objective was to determine faculty's knowledge of electronic resources, access to a computer, use of electronic resources (both number and frequency) available at the Medical Sciences Library (MSL), and the areas of training needed and to identify areas for further research. Methods: A survey was administered to faculty in medicine, pharmacy, dentistry, and veterinary sciences at The University of the West Indies. The questions covered computer literacy, computer access and location, knowledge and use of electronic resources, and training needs. Results: The response rate was 70%, of whom 97% were computer users. Seventy-three percent used computers daily, and 82% felt that their computer literacy level was average or beyond. Overall, it was found that faculty had high awareness of the electronic resources made available by the MSL but low use of MSL-specific resources supporting the suggested problem of underutilization. Many respondents felt that e-resources were important, and, though many felt that they were competent users, 83% were self-taught and many still expressed a need for training. Over 60% felt that a workshop with a hands-on component was the preferred format for training. It was recommended that there be greater promotion of the library's e-resources. PMID:15685270

  19. A preliminary categorization of end-of-life electrical and electronic equipment as secondary metal resources.

    PubMed

    Oguchi, Masahiro; Murakami, Shinsuke; Sakanakura, Hirofumi; Kida, Akiko; Kameya, Takashi

    2011-01-01

    End-of-life electrical and electronic equipment (EEE) has recently received attention as a secondary source of metals. This study examined characteristics of end-of-life EEE as secondary metal resources to consider efficient collection and metal recovery systems according to the specific metals and types of EEE. We constructed an analogy between natural resource development and metal recovery from end-of-life EEE and found that metal content and total annual amount of metal contained in each type of end-of-life EEE should be considered in secondary resource development, as well as the collectability of the end-of-life products. We then categorized 21 EEE types into five groups and discussed their potential as secondary metal resources. Refrigerators, washing machines, air conditioners, and CRT TVs were evaluated as the most important sources of common metals, and personal computers, mobile phones, and video games were evaluated as the most important sources of precious metals. Several types of small digital equipment were also identified as important sources of precious metals; however, mid-size information and communication technology (ICT) equipment (e.g., printers and fax machines) and audio/video equipment were shown to be more important as a source of a variety of less common metals. The physical collectability of each type of EEE was roughly characterized by unit size and number of end-of-life products generated annually. Current collection systems in Japan were examined and potentially appropriate collection methods were suggested for equipment types that currently have no specific collection systems in Japan, particularly for video games, notebook computers, and mid-size ICT and audio/video equipment. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Unique program aims to connect frequent ED utilizers with medical homes, resources to meet complex needs.

    PubMed

    2014-10-01

    Sinai Hospital of Baltimore in Baltimore, MD, is partnering with HealthCare Access Maryland, a non-profit organization in the state, to link patients who frequent the ED for care with medical homes and other resources that can better meet their medical and social needs. Under the Access Health Program, ED-based care coordinators intervene with patients who meet program criteria, linking them with medical homes and other resources that address their complex needs. The hospital has devised a flag to notify the ED when a frequent-utilizing patient presents in the department for care. Care coordinators then meet with these patients and get their consent to participate in the program. Within a week of the ED visit, care coordinators schedule a home visit with the patient to establish a care plan containing specific goals and a time frame to carry out these goals. Patients remain in the program for 90 days as care coordinators work to hand them off to longer-term resources. Many of the patients enrolled in the program have substance abuse and mental health problems. Patients are also often uninsured and/or homeless. Within two months of launching the program, care coordinators enrolled 74 patients, with the goal of eventually bringing that number to 200.

  1. Electronic structure of the complex hydride NaAlH4

    NASA Astrophysics Data System (ADS)

    Aguayo, A.; Singh, D. J.

    2004-04-01

    Density-functional calculations of the electronic structure of the complex hydride NaAlH4 and the reference systems NaH and AlH3 are reported. We find a substantially ionic electronic structure for NaAlH4, which emphasizes the importance of solid-state effects in this material. The relaxed hydrogen positions in NaAlH4 are in good agreement with the recent experiment. The electronic structure of AlH3 is also ionic. Implications for the binding of complex hydrides are discussed.

  2. Flip-chip advantages for complex electronics in microsystems

    NASA Astrophysics Data System (ADS)

    Riley, George A.

    1999-08-01

    This paper compares several methods of flip chip assembly suitable for complex high-density micro-systems and discusses the advantages and disadvantages of each, based on our results in eight years of flip chip development and production. Flip chip advantages over other chip interconnection methods include smaller size, better electrical performance, and greater ruggedness. Many new methods of flip chip assembly have become available as alternatives to the venerable solder bump flip chip technology. These newer methods offer finer pitch connections, lower temperature processing, and more design flexibility than the older solder bump approach. In particular, the stud bump/adhesive flip chip method allows assemblies starting from individual die, rather than requiring full wafers. This singulated chip approach is more economical, faster to implement and modify, and avoids the `known good die' problems inherent in wafer-based flip chip processes. Stud bump flip chip, as described here, permits easy prototyping and micro-scale breadboarding during development, and rapid transition to production.

  3. Metal complex-based electron-transfer mediators in dye-sensitized solar cells

    DOEpatents

    Elliott, C. Michael; Sapp, Shawn A.; Bignozzi, Carlo Alberto; Contado, Cristiano; Caramori, Stefano

    2006-03-28

    This present invention provides a metal-ligand complex and methods for using and preparing the same. In particular, the metal-ligand complex of the present invention is of the formula: L.sub.a-M-X.sub.b where L, M, X, a, and b are those define herein. The metal-ligand complexes of the present invention are useful in a variety of applications including as electron-transfer mediators in dye-sensitized solar cells and related photoelectrochromic devices.

  4. Photoinduced electron transfer reactions of ruthenium(II)-complexes containing amino acid with quinones.

    PubMed

    Eswaran, Rajkumar; Kalayar, Swarnalatha; Paulpandian, Muthu Mareeswaran; Seenivasan, Rajagopal

    2014-05-01

    With the aim of mimicking, at basic level the photoinduced electron transfer process in the reaction center of photosystem II, ruthenium(II)-polypyridyl complexes, carrying amino acids were synthesized and studied their photoinduced electron transfer reactions with quinones by steady state and time resolved measurements. The reaction of quinones with excited state of ruthenium(II)-complexes, I-V in acetonitrile has been studied by luminescence quenching technique and the rate constant, k(q), values are close to the diffusion controlled rate. The detection of the semiquinone anion radical in this system using time-resolved transient absorption spectroscopy confirms the electron transfer nature of the reaction. The semiclassical theory of electron transfer has been successfully applied to the photoluminescence quenching of Ru(II)-complexes with quinones.

  5. Reactivity of seventeen- and nineteen-valence electron complexes in organometallic chemistry

    NASA Technical Reports Server (NTRS)

    Stiegman, Albert E.; Tyler, David R.

    1986-01-01

    A guideline to the reactivity of 17- and 19-valence electron species in organometallic chemistry is proposed which the authors believe will supersede all others. The thesis holds that the reactions of 17-electron metal radicals are associatively activated with reactions proceeding through a 19-valence electron species. The disparate reaction chemistry of the 17-electron metal radicals are unified in terms of this associative reaction pathway, and the intermediacy of 19-valence electron complexes in producing the observed products is discussed. It is suggested that related associatively activated pathways need to be considered in some reactions that are thought to occur by more conventional routes involving 16- and 18-electron intermediates. The basic reaction chemistry and electronic structures of these species are briefly discussed.

  6. Reactivity of seventeen- and nineteen-valence electron complexes in organometallic chemistry

    NASA Technical Reports Server (NTRS)

    Stiegman, Albert E.; Tyler, David R.

    1986-01-01

    A guideline to the reactivity of 17- and 19-valence electron species in organometallic chemistry is proposed which the authors believe will supersede all others. The thesis holds that the reactions of 17-electron metal radicals are associatively activated with reactions proceeding through a 19-valence electron species. The disparate reaction chemistry of the 17-electron metal radicals are unified in terms of this associative reaction pathway, and the intermediacy of 19-valence electron complexes in producing the observed products is discussed. It is suggested that related associatively activated pathways need to be considered in some reactions that are thought to occur by more conventional routes involving 16- and 18-electron intermediates. The basic reaction chemistry and electronic structures of these species are briefly discussed.

  7. Combining gas phase electron capture and IRMPD action spectroscopy to probe the electronic structure of a metastable reduced organometallic complex containing a non-innocent ligand.

    PubMed

    Katari, Madanakrishna; Payen de la Garanderie, Eleonore; Nicol, Edith; Steinmetz, Vincent; van der Rest, Guillaume; Carmichael, Duncan; Frison, Gilles

    2015-10-21

    Combining electron capture dissociation mass spectrometry and infrared multiple photon dissociation action spectroscopy allows the formation, selection and characterisation of reduced metal complexes containing non-innocent ligands. Zinc complexes containing diazafluorenone ligands have been studied and the localisation of the single electron on the metal atom in the mono-ligated complex has been demonstrated.

  8. Photoelectron Spectroscopy of Hexachloroplatinate-Nucleobase Complexes: Nucleobase Excited State Decay Observed via Delayed Electron Emission

    SciTech Connect

    Sen, Ananya; Matthews, Edward M.; Hou, Gao-Lei; Wang, Xue B.; Dessent, Caroline

    2015-11-14

    We report low-temperature photoelectron spectra of isolated gas-phase complexes of the hexachloroplatinate dianion bound to the nucleobases uracil, thymine, cytosine and adenine. The spectra display well-resolved, distinct peaks that are consistent with complexes where the hexachloroplatinate dianion is largely intact. Adiabatic electron detachment energies for the hexachloroplatinate-nucleobase complexes are measured as 2.26-2.36 eV. The magnitudes of the repulsive Coulomb barriers (RCBs) of the complexes are all ~1.7 eV, values that are lower than the RCB of the uncomplexed PtCl6 2- dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photoelectron spectra of the four clusters. The 266 nm spectra of the PtCl6 2-∙thymine and PtCl6 2-∙adenine complexes also display very prominent delayed electron emission bands. These results mirror recent results on the related Pt(CN)4 2-∙nucleobase complexes [Sen et al, J. Phys. Chem. B, 119, 11626, 2015]. The observation of delayed electron emission bands in the PtCl6 2-∙nucleobase spectra obtained in this work, as for the previously studied Pt(CN)4 2-∙nucleobase complexes, is attributed to onephoton excitation of nucleobase-centred excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment. Moreover, the selective, strong excitation of the delayed emission bands in the 266 nm spectra is linked to fundamental differences in the individual nucleobase photophysics at this excitation energy. This strongly supports our previous suggestion that the dianion within these clusters can be viewed as a “dynamic tag” which has the propensity to emit electrons when the attached nucleobase decays over a timescale long enough to allow autodetachment.

  9. Photoelectron spectroscopy of hexachloroplatinate-nucleobase complexes: Nucleobase excited state decay observed via delayed electron emission.

    PubMed

    Sen, Ananya; Matthews, Edward M; Hou, Gao-Lei; Wang, Xue-Bin; Dessent, Caroline E H

    2015-11-14

    We report low-temperature photoelectron spectra of isolated gas-phase complexes of the hexachloroplatinate dianion bound to the nucleobases uracil, thymine, cytosine, and adenine. The spectra display well-resolved, distinct peaks that are consistent with complexes where the hexachloroplatinate dianion is largely intact. Adiabatic electron detachment energies for the hexachloroplatinate-nucleobase complexes are measured as 2.26-2.36 eV. The magnitudes of the repulsive Coulomb barriers (RCBs) of the complexes are all ∼1.7 eV, values that are lower than the RCB of the uncomplexed PtCl6 (2-) dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photoelectron spectra of the four clusters. The 266 nm spectra of the PtCl6 (2-) ⋅ thymine and PtCl6 (2-) ⋅ adenine complexes also display very prominent delayed electron emission bands. These results mirror recent results on the related Pt(CN)4 (2-) ⋅ nucleobase complexes [A. Sen et al., J. Phys. Chem. B 119, 11626 (2015)]. The observation of delayed electron emission bands in the PtCl6 (2-) ⋅ nucleobase spectra obtained in this work, as for the previously studied Pt(CN)4 (2-) ⋅ nucleobase complexes, is attributed to one-photon excitation of nucleobase-centred excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment. Moreover, the selective, strong excitation of the delayed emission bands in the 266 nm spectra is linked to fundamental differences in the individual nucleobase photophysics at this excitation energy. This strongly supports our previous suggestion that the dianion within these clusters can be viewed as a "dynamic tag" which has the propensity to emit electrons when the attached nucleobase decays over a time scale long enough to allow autodetachment.

  10. Ultrafast Charge Recombination Dynamics in Ternary Electron Donor-Acceptor Complexes: (Benzene)2-Tetracyanoethylene Complexes.

    PubMed

    Chiu, Chih-Chung; Hung, Chih-Chang; Cheng, Po-Yuan

    2016-12-08

    The charge-transfer (CT) state relaxation dynamics of the binary (1:1) and ternary (2:1) benzene/tetracyanoethylene (BZ/TCNE) complexes are reported. Steady-state and ultrafast time-resolved broadband fluorescence (TRFL) spectra of TCNE dissolved in a series of BZ/CCl4 mixed solvents are measured to elucidate the spectroscopic properties of the BZ/TCNE complexes and their CT-state relaxation dynamics. Both steady-state and TRFL spectra exhibit marked BZ concentration dependences, which can be attributed to the formation of two types of 2:1 complexes in the ground and excited states. By combining with the density functional theory (DFT) calculations, it was concluded that the BZ concentration dependence of the absorption spectra is mainly due to the formation and excitation of the sandwich-type 2:1 ternary complexes, whereas the changes in fluorescence spectra at high BZ concentrations are due to the formation of the asymmetric-type 2:1 ternary complex CT1 state. A unified mechanism involving both direct excitation and secondary formation of the 2:1 complexes CT states are proposed to account for the observations. The equilibrium charge recombination (CR) time constant of the 1:1 CT1 state is determined to be ∼150 ps in CCl4, whereas that of the 2:1 DDA-type CT1 state becomes ∼70 ps in 10% BZ/CCl4 and ∼34 ps in pure BZ. The CR rates and the CT1-S0 energy gap of these complexes in different solvents exhibit a correlation conforming to the Marcus inverted region. It is concluded that partial charge resonance occurring between the two adjacent BZs in the asymmetric-type 2:1 CT1-state reduces the CR reaction exothermicity and increases the CR rate.

  11. Influence of Electron-Withdrawing Substituents on the Electronic Structure of Oxidized Ni and Cu Salen Complexes.

    PubMed

    Chiang, Linus; Herasymchuk, Khrystyna; Thomas, Fabrice; Storr, Tim

    2015-06-15

    Nickel (Ni(Sal(CF3))) and copper (Cu(Sal(CF3))) complexes of an electron-poor salen ligand were prepared, and their one-electron oxidized counterparts were studied using an array of spectroscopic and theoretical methods. The electrochemistry of both complexes exhibited quasi-reversible redox processes at higher potentials in comparison to the M(Sal(R)) (R = (t)Bu, OMe, NMe2) analogues, in line with the electron-withdrawing nature of the para-CF3 substituent. Chemical oxidation, monitored by ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, afforded their corresponding one-electron oxidized products. Ligand-based oxidation was observed for [Ni(Sal(CF3))](+•), as evidenced by sharp NIR transitions in the UV-vis-NIR spectrum and a broad isotropic signal at g = 2.067 by solution electron paramagnetic resonance (EPR) spectroscopy. Such sharp NIR transitions observed for [Ni(Sal(CF3))](+•) are indicative of a delocalized electronic structure, which is in good agreement with electrochemical measurements and density functional theory (DFT) calculations. In addition, the increased Lewis acidity of [Ni(Sal(CF3))](+•), evident from the EPR g-value and DFT calculations, was further quantified by the binding affinity of axial ligands to [Ni(Sal(CF3))](+•). For [Cu(Sal(CF3))](+), an intense ligand-to-metal charge transfer band at 18 700 cm(-1) in the UV-vis-NIR spectrum was observed, which is diagnostic for the formation of a Cu(III) species [J. Am. Chem. Soc., 2008, 130, 15448-15459]. The Cu(III) character for [Cu(Sal(CF3))](+) is further confirmed by (19)F NMR analysis. Taken together, these results show that the electron-deficient salen ligand H2Sal(CF3) increases the Lewis acidity of the coordinating metal center.

  12. Medical Image Resource Center--making electronic teaching files from PACS.

    PubMed

    Lim, C C Tchoyoson; Yang, Guo Liang; Nowinski, Wieslaw L; Hui, Francis

    2003-12-01

    A picture archive and communications system (PACS) is a rich source of images and data suitable for creating electronic teaching files (ETF). However, the potential for PACS to support nonclinical applications has not been fully realized: at present there is no mechanism for PACS to identify and store teaching files; neither is there a standardized method for sharing such teaching images. The Medical Image Resource Center (MIRC) is a new central image repository that defines standards for data exchange among different centers. We developed an ETF server that retrieves digital imaging and communication in medicine (DICOM) images from PACS, and enables users to create teaching files that conform to the new MIRC schema. We test-populated our ETF server with illustrative images from the clinical case load of the National Neuroscience Institute, Singapore. Together, PACS and MIRC have the potential to benefit radiology teaching and research.

  13. Correlative super-resolution fluorescence and electron microscopy of the nuclear pore complex with molecular resolution.

    PubMed

    Löschberger, Anna; Franke, Christian; Krohne, Georg; van de Linde, Sebastian; Sauer, Markus

    2014-10-15

    Here, we combine super-resolution fluorescence localization microscopy with scanning electron microscopy to map the position of proteins of nuclear pore complexes in isolated Xenopus laevis oocyte nuclear envelopes with molecular resolution in both imaging modes. We use the periodic molecular structure of the nuclear pore complex to superimpose direct stochastic optical reconstruction microscopy images with a precision of <20 nm on electron micrographs. The correlative images demonstrate quantitative molecular labeling and localization of nuclear pore complex proteins by standard immunocytochemistry with primary and secondary antibodies and reveal that the nuclear pore complex is composed of eight gp210 (also known as NUP210) protein homodimers. In addition, we find subpopulations of nuclear pore complexes with ninefold symmetry, which are found occasionally among the more typical eightfold symmetrical structures. © 2014. Published by The Company of Biologists Ltd.

  14. Resources.

    ERIC Educational Resources Information Center

    Aviation/Space, 1980

    1980-01-01

    The resources listed different types of materials related to the aerospace science under specified categories: free materials and inexpensive, selected government publication, audiovisual (government, nongovernment), aviation books, and space books. The list includes the publisher's name and the price for each publication. (SK)

  15. Resources.

    ERIC Educational Resources Information Center

    Stewart, John; MacDonald, Ian

    1980-01-01

    Presents a guide to resources on television drama available to teachers for classroom use in television curriculum. Lists American and British television drama videorecordings of both series and individual presentations and offers a bibliography of "one-off" single fiction plays produced for British television. (JMF)

  16. Resources.

    ERIC Educational Resources Information Center

    Aviation/Space, 1980

    1980-01-01

    The resources listed different types of materials related to the aerospace science under specified categories: free materials and inexpensive, selected government publication, audiovisual (government, nongovernment), aviation books, and space books. The list includes the publisher's name and the price for each publication. (SK)

  17. Electronic properties and electron-phonon interaction in complex, multicomponent alloys in application to high-entropy alloys

    NASA Astrophysics Data System (ADS)

    Samolyuk, German; Daene, Markus; Stocks, George Malcolm; Caro, Jose Alfredo; Stoller, Roger

    2015-03-01

    High-entropy alloys (HEAs) have recently been developed as nontraditional alloy systems. They are composed of multiple elements at or near equiatomic ratios that form random solid solutions on simple underlying fcc or bcc lattices. In recent years HEAs have attracted significant attention due to their high strength, ductility and possible high radiation resistance. The complexity of the alloys results in very interesting electronic system behavior. Even in thermal equilibrium, disorder, especially extreme disorder, has important impacts on all electronic, atomic, and magnetic properties. In the current work we present results of first principle investigation of the electronic and magnetic properties of Ni-based multicomponent concentrated alloys using the coherent potential approximation (CPA). The influence of electronic structure modifications on the electron mean free path and values of electron-phonon coupling are calculated, together with preliminary results on similar quantities obtained by Time Dependent DFT. We discuss possible effects of tuning the mean free path and energy dissipation mechanisms to defect production and recombination in HEAs under irradiation.

  18. The shadow uniform resource locator: standardizing citations of electronically published materials.

    PubMed

    DiCarlo, J V; Pastor, X; Markovitz, B P

    2000-01-01

    Citation of scientific materials published on the Internet is often cumbersome because of unwieldy uniform resource locators (URLs). The authors describe a format for URLs that simplifies citation of scholarly materials. Its use depends on a simple HTML device, the "refresh page." Uniform citation would follow this format: [Author I. Title of article. http:// domain/year/month-day(e#).html]. The HTML code for such a page is: (HTML) (head) (meta HTTP-EQUIV="Refresh" CONTENT="0; URL= http://Actual-URL/ for-article/ referred-to/ incitation.html") (/head) (/HTML). The code instructs the browser to suppress the content of the refresh page and bring up the title page of the cited article instead. Citations would be succinct and predictable. An electronic journal would not need to alter its existing file hierarchy but would need to establish a distinct domain name and maintain a file of refresh pages. Utilization of the "shadow" URL would bring us one step closer to truly universal resource locators.

  19. Using mobile electronic devices to deliver educational resources in developing countries.

    PubMed

    Mazal, Jonathan Robert; Ludwig, Rebecca

    2015-01-01

    Developing countries have far fewer trained radiography professionals than developed countries, which exacerbates the limited access to imaging services. The lack of trained radiographers reflects, in part, limited availability of radiographer-specific educational resources. Historically, organizations that provided such resources in the developing world faced challenges related to the limited stock of current materials as well as expenses associated with shipping and delivery. Four mobile electronic devices (MEDs) were loaded with educational content (e-books, PDFs, and digital applications) spanning major radiography topics. The MEDs were distributed to 4 imaging departments in Ghana, India, Nepal, and Nigeria based on evidence of need for radiography-specific resources, as revealed by survey responses. A cost comparison of postal delivery vs digital delivery of educational content was performed. The effectiveness of delivering additional content via Wi-Fi transmission also was evaluated. Feedback was solicited on users' experience with the MEDs as a delivery tool for educational content. An initial average per e-book expense of $30.05, which included the cost of the device, was calculated for the MED delivery method compared with $15.56 for postal delivery of printed materials. The cost of the MED delivery method was reduced to an average of $10.05 for subsequent e-book deliveries. Additional content was successfully delivered via Wi-Fi transmission to all recipients during the 3-month follow-up period. Overall user feedback on the experience was positive, and ideas for enhancing the MED-based method were identified. Using MEDs to deliver radiography-specific educational content appears to be more cost effective than postal delivery of printed materials on a long-term basis. MEDs are more efficient for providing updates to educational materials. Customization of content to department needs, and using projector devices could enhance the usefulness of MEDs for

  20. Influence of Humic Acid Complexation with Metal Ions on Extracellular Electron Transfer Activity

    NASA Astrophysics Data System (ADS)

    Zhou, Shungui; Chen, Shanshan; Yuan, Yong; Lu, Qin

    2015-11-01

    Humic acids (HAs) can act as electron shuttles and mediate biogeochemical cycles, thereby influencing the transformation of nutrients and environmental pollutants. HAs commonly complex with metals in the environment, but few studies have focused on how these metals affect the roles of HAs in extracellular electron transfer (EET). In this study, HA-metal (HA-M) complexes (HA-Fe, HA-Cu, and HA-Al) were prepared and characterized. The electron shuttle capacities of HA-M complexes were experimentally evaluated through microbial Fe(III) reduction, biocurrent generation, and microbial azoreduction. The results show that the electron shuttle capacities of HAs were enhanced after complexation with Fe but were weakened when using Cu or Al. Density functional theory calculations were performed to explore the structural geometry of the HA-M complexes and revealed the best binding sites of the HAs to metals and the varied charge transfer rate constants (k). The EET activity of the HA-M complexes were in the order HA-Fe > HA-Cu > HA-Al. These findings have important implications for biogeochemical redox processes given the ubiquitous nature of both HAs and various metals in the environment.

  1. Influence of Humic Acid Complexation with Metal Ions on Extracellular Electron Transfer Activity

    PubMed Central

    Zhou, Shungui; Chen, Shanshan; Yuan, Yong; Lu, Qin

    2015-01-01

    Humic acids (HAs) can act as electron shuttles and mediate biogeochemical cycles, thereby influencing the transformation of nutrients and environmental pollutants. HAs commonly complex with metals in the environment, but few studies have focused on how these metals affect the roles of HAs in extracellular electron transfer (EET). In this study, HA-metal (HA-M) complexes (HA-Fe, HA-Cu, and HA-Al) were prepared and characterized. The electron shuttle capacities of HA-M complexes were experimentally evaluated through microbial Fe(III) reduction, biocurrent generation, and microbial azoreduction. The results show that the electron shuttle capacities of HAs were enhanced after complexation with Fe but were weakened when using Cu or Al. Density functional theory calculations were performed to explore the structural geometry of the HA-M complexes and revealed the best binding sites of the HAs to metals and the varied charge transfer rate constants (k). The EET activity of the HA-M complexes were in the order HA-Fe > HA-Cu > HA-Al. These findings have important implications for biogeochemical redox processes given the ubiquitous nature of both HAs and various metals in the environment. PMID:26593782

  2. Influence of Humic Acid Complexation with Metal Ions on Extracellular Electron Transfer Activity.

    PubMed

    Zhou, Shungui; Chen, Shanshan; Yuan, Yong; Lu, Qin

    2015-11-23

    Humic acids (HAs) can act as electron shuttles and mediate biogeochemical cycles, thereby influencing the transformation of nutrients and environmental pollutants. HAs commonly complex with metals in the environment, but few studies have focused on how these metals affect the roles of HAs in extracellular electron transfer (EET). In this study, HA-metal (HA-M) complexes (HA-Fe, HA-Cu, and HA-Al) were prepared and characterized. The electron shuttle capacities of HA-M complexes were experimentally evaluated through microbial Fe(III) reduction, biocurrent generation, and microbial azoreduction. The results show that the electron shuttle capacities of HAs were enhanced after complexation with Fe but were weakened when using Cu or Al. Density functional theory calculations were performed to explore the structural geometry of the HA-M complexes and revealed the best binding sites of the HAs to metals and the varied charge transfer rate constants (k). The EET activity of the HA-M complexes were in the order HA-Fe > HA-Cu > HA-Al. These findings have important implications for biogeochemical redox processes given the ubiquitous nature of both HAs and various metals in the environment.

  3. Role of protein fluctuation correlations in electron transfer in photosynthetic complexes.

    PubMed

    Nesterov, Alexander I; Berman, Gennady P

    2015-04-01

    We consider the dependence of the electron transfer in photosynthetic complexes on correlation properties of random fluctuations of the protein environment. The electron subsystem is modeled by a finite network of connected electron (exciton) sites. The fluctuations of the protein environment are modeled by random telegraph processes, which act either collectively (correlated) or independently (uncorrelated) on the electron sites. We derived an exact closed system of first-order linear differential equations with constant coefficients, for the average density matrix elements and for their first moments. Under some conditions, we obtained analytic expressions for the electron transfer rates and found the range of parameters for their applicability by comparing with the exact numerical simulations. We also compared the correlated and uncorrelated regimes and demonstrated numerically that the uncorrelated fluctuations of the protein environment can, under some conditions, either increase or decrease the electron transfer rates.

  4. Mathematical model and software complex for computer simulation of field emission electron sources

    SciTech Connect

    Nikiforov, Konstantin

    2015-03-10

    The software complex developed in MATLAB allows modelling of function of diode and triode structures based on field emission electron sources with complex sub-micron geometry, their volt-ampere characteristics, calculating distribution of electric field for educational and research needs. The goal of this paper is describing the physical-mathematical model, calculation methods and algorithms the software complex is based on, demonstrating the principles of its function and showing results of its work. For getting to know the complex, a demo version with graphical user interface is presented.

  5. Proton-coupled electron transfer and multielectron oxidations in complexes of ruthenium and osmium

    SciTech Connect

    Dovletoglou, A.

    1992-01-01

    This doctoral research concerns the mechanism of proton-coupled electron transfer over an extended pH range. These processes between ruthenium and osmium complexes and hydroquinones have been studied using spectrophotometric methods and cyclic voltammetry. Elucidation of the mechanistic details has been attempted by using isotopic labelling, kinetic analysis, and numerical simulation of complex kinetic schemes. The coordination and redox chemistry of polypyridyl-acetylacetonato and -oxalato complexes of ruthenium and the role of ancillary ligands in defining the properties of Ru[sup IV]O complexes were explored. These studies represent the first attempt to probe possible 2e[sup [minus

  6. Effects of limited resources in 3D real-time simulation of an extended ECHO complex adaptive system model

    NASA Astrophysics Data System (ADS)

    Dominiak, Dana M.; Rinaldo, Frank; Evans, Martha W.

    2001-08-01

    An evolutionary model of adaptive agents called `ECHO' was proposed by John Holland. ECHO is a first step toward mathematical theory in the field of complex adaptive systems. Researchers in numerous disciplines have used the existing ECHO simulation both to model and to explain complex system behaviors. This paper describes the effects of limited resources in a 3D simulation of an extended Holland ECHO model. In this simulation, adaptive agents move about the ECHO terrain and interact with other agents in real-time. Adaptive agents are bred using a genetic algorithm. The model's environment contains limited resources, represented as symbols. Elaborate relationships are developed by the agents to utilize resources through both competition and cooperation. Researchers have a better tool by which to identify and explain complex adaptive system behavior by observing the emergence of complexity first hand.

  7. Electronic structure and optical properties of the intrinsically chiral 16-electron superatom complex [Au20(PP3)4](4+).

    PubMed

    Knoppe, Stefan; Lehtovaara, Lauri; Häkkinen, Hannu

    2014-06-12

    The recently solved crystal structure of the [Au20(PP3)4]Cl4 cluster (PP3: tris(2-(diphenylphophino)ethyl)phosphine) is examined using density functional theory (DFT). The Au20 core of the cluster is intrinsically chiral by the arrangement of the Au atoms. This is in contrast to the chirality of thiolate-protected gold clusters, in which the protecting Au-thiolate units are arranged in chiral patterns on achiral cores. We interpret the electronic structure of the [Au20(PP3)4]Cl4 cluster in terms of the superatom complex model. The 16-electron cluster cannot be interpreted as a dimer of 8-electron clusters (which are magic). Instead, a superatomic electron configuration of 1S(2) 1P(6) 1D(6) 2S(2) is found. The 2S band is strongly stabilized, and the 1D states are nondegenerate with a large gap. Ligand protection of the (Au20)(4+) core leads to a significant increase of the HL-gap and thus stabilization. We also tested a charge of +II, which would give rise to an 18-electron superatom complex. Our results indicate that the 16-electron cluster is indeed more stable. We also investigate the optical properties of the cluster. The experimental absorption spectrum is well-reproduced by time-dependent DFT. Prominent transitions are analyzed by time-dependent density-functional perturbation theory. The intrinsic chirality of the cluster is compared to that of Au38(SR)24. We observe that the chiral arrangement of the protecting Au-SR units in Au38(SR)24 has very strong influence on the strength of the CD spectra, whereas phosphine protection in the title compound does not.

  8. Tunable entanglement resource in elastic electron-exchange collisions out of chaotic spin systems

    NASA Astrophysics Data System (ADS)

    Lohmann, B.; Blum, K.; Langer, B.

    2016-09-01

    Elastic collisions between initially unpolarized electrons and hydrogenlike atoms are discussed aiming to analyze the entanglement properties of the correlated final spin system. Explicit spin-dependent interactions are neglected and electron exchange only is taken into account. We show the final spin system to be completely characterized by a single spin correlation parameter depending on scattering angle and energy. Its numerical value identifies the final spins of the collision partners to be either in the separable, entangled, or Bell correlated regions. The symmetry of the scattering process allows for the construction of explicit examples applying methods of classical communication and local operations for illustrating the concepts of nonlocality versus separability. It is shown that strong correlations can be produced violating Bell's inequalities significantly. Furthermore, the degree of entanglement can be continuously varied simply by changing either the scattering angle and/or energy. This allows for the generation of tunable spin pairs with any desired degree of entanglement. It is suggested to use such nonlocally entangled spin pairs as a resource for further experiments, for example in quantum information processes.

  9. Plastics disassembly versus bulk recycling: engineering design for end-of-life electronics resource recovery.

    PubMed

    Rios, Pedro; Stuart, Julie Ann; Grant, Ed

    2003-12-01

    Annual plastic flows through the business and consumer electronics manufacturing supply chain include nearly 3 billion lb of high-value engineering plastics derived from petroleum. The recovery of resource value from this stream presents critical challenges in areas of materials identification and recycling process design that demand new green engineering technologies applied together with life cycle assessment and ecological supply chain analysis to create viable plastics-to-plastics supply cycles. The sustainable recovery of potentially high-value engineering plastics streams requires that recyclers either avoid mixing plastic parts or purify later by separating smaller plastic pieces created in volume reduction (shredding) steps. Identification and separation constitute significant barriers in the plastics-to-plastics recycling value proposition. In the present work, we develop a model that accepts randomly arriving electronic products to study scenarios by which a recycler might identify and separate high-value engineering plastics as well as metals. Using discrete eventsimulation,we compare current mixed plastics recovery with spectrochemical plastic resin identification and subsequent sorting. Our results show that limited disassembly with whole-part identification can produce substantial yields in separated streams of recovered engineering thermoplastics. We find that disassembly with identification does not constitute a bottleneck, but rather, with relatively few workers, can be configured to pull the process and thus decrease maximum staging space requirements.

  10. Tuberous sclerosis complex: a survey of health care resource use and health burden.

    PubMed

    Rentz, Anne M; Skalicky, Anne M; Liu, Zhimei; Wheless, James W; Dunn, David W; Frost, Michael D; Nakagawa, JoAnne; Magestro, Matthew; Prestifilippo, Judith

    2015-04-01

    Tuberous sclerosis complex (TSC) is a multiorgan, autosomal-dominant genetic disorder with incomplete penetrance. This analysis of a web-based survey focuses on the clinical presentation, management, and associated burden of patients with TSC in the United States. A total of 676 TSC patients or caregivers responded. Both pediatric and adult patient groups experienced skin lesions (77% and 44%), seizures (77% and 24%), and kidney complications (33% and 25%) as well as other manifestations. Patient groups averaged 22 visits to a physician, nine procedures/tests, two emergency room visits, and two hospital admissions in the past year. Standardized tests were administered for health-related quality of life and TSC patients reported significantly worse mental health scores and better physical health scores compared to a normative sample of cancer patients. Results demonstrate that TSC is associated with significant clinical burden, resource utilization, and decreased mental health well-being. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Navigating a strange and complex environment: experiences of Sudanese refugee women using a new nutrition resource

    PubMed Central

    Mannion, Cynthia A; Raffin-Bouchal, Shelley; Henshaw, Christena Jane

    2014-01-01

    Background Refugees experience dietary changes as part of the daily challenges they face resettling in a new country. Sudanese women seek to care and feed their families, but face language barriers in the marketplace, limited access to familiar foods, and forced new food choices. This study aimed to understand the acceptability of a purse-sized nutrition resource, “The Market Guide”, which was developed to help recently immigrated Sudanese refugee women identify and purchase healthy foods and navigate grocery stores. Methods Eight women participated in a focus group, four of whom were also observed during accompanied grocery store visits. Individual interviews were conducted with four health care workers at the resettlement center to gather perceptions about the suitability of The Market Guide. Focus groups and interviews were audiotaped and transcribed. Data from field notes and transcripts were analyzed using grounded theory for preliminary open codes, followed by selective and theoretical coding. Results The Market Guide was of limited use to Sudanese women. Their response to this resource revealed the struggles of women acculturating during their first year in Calgary, Canada. We discovered the basic social process, “Navigating through a strange and complex environment: learning ways to feed your family.” Language, transportation, and an unfamiliar marketplace challenged women and prevented them from exercising their customary role of “knowing” which foods were “safe and good” for their families. The nutrition resource fell short of informing food choices and purchases, and we discovered that “learning to feed your family” is a relational process where trusted persons, family, and friends help navigate dietary acculturation. Conclusion Emergent theory based on the basic social process may help health care professionals consider relational learning when planning health promotion and nutrition activities with Sudanese families. PMID:24790470

  12. SAGES: A Suite of Freely-Available Software Tools for Electronic Disease Surveillance in Resource-Limited Settings

    PubMed Central

    Lewis, Sheri L.; Feighner, Brian H.; Loschen, Wayne A.; Wojcik, Richard A.; Skora, Joseph F.; Coberly, Jacqueline S.; Blazes, David L.

    2011-01-01

    Public health surveillance is undergoing a revolution driven by advances in the field of information technology. Many countries have experienced vast improvements in the collection, ingestion, analysis, visualization, and dissemination of public health data. Resource-limited countries have lagged behind due to challenges in information technology infrastructure, public health resources, and the costs of proprietary software. The Suite for Automated Global Electronic bioSurveillance (SAGES) is a collection of modular, flexible, freely-available software tools for electronic disease surveillance in resource-limited settings. One or more SAGES tools may be used in concert with existing surveillance applications or the SAGES tools may be used en masse for an end-to-end biosurveillance capability. This flexibility allows for the development of an inexpensive, customized, and sustainable disease surveillance system. The ability to rapidly assess anomalous disease activity may lead to more efficient use of limited resources and better compliance with World Health Organization International Health Regulations. PMID:21572957

  13. SAGES: a suite of freely-available software tools for electronic disease surveillance in resource-limited settings.

    PubMed

    Lewis, Sheri L; Feighner, Brian H; Loschen, Wayne A; Wojcik, Richard A; Skora, Joseph F; Coberly, Jacqueline S; Blazes, David L

    2011-05-10

    Public health surveillance is undergoing a revolution driven by advances in the field of information technology. Many countries have experienced vast improvements in the collection, ingestion, analysis, visualization, and dissemination of public health data. Resource-limited countries have lagged behind due to challenges in information technology infrastructure, public health resources, and the costs of proprietary software. The Suite for Automated Global Electronic bioSurveillance (SAGES) is a collection of modular, flexible, freely-available software tools for electronic disease surveillance in resource-limited settings. One or more SAGES tools may be used in concert with existing surveillance applications or the SAGES tools may be used en masse for an end-to-end biosurveillance capability. This flexibility allows for the development of an inexpensive, customized, and sustainable disease surveillance system. The ability to rapidly assess anomalous disease activity may lead to more efficient use of limited resources and better compliance with World Health Organization International Health Regulations.

  14. Rare Earth Complex as Electron Trapper and Energy Transfer Ladder for Efficient Red Iridium Complex Based Electroluminescent Devices.

    PubMed

    Zhou, Liang; Li, Leijiao; Jiang, Yunlong; Cui, Rongzhen; Li, Yanan; Zhao, Xuesen; Zhang, Hongjie

    2015-07-29

    In this work, we experimentally demonstrated the new functions of trivalent rare earth complex in improving the electroluminescent (EL) performances of iridium complex by codoping trace Eu(TTA)3phen (TTA = thenoyltrifluoroacetone, phen = 1,10-phenanthroline) into a light-emitting layer based on PQ2Ir(dpm) (iridium(III)bis(2-phenylquinoly-N,C(2'))dipivaloylmethane). Compared with a reference device, the codoped devices displayed higher efficiencies, slower efficiency roll-off, higher brightness, and even better color purity. Experimental results demonstrated that Eu(TTA)3phen molecules function as electron trappers due to its low-lying energy levels, which are helpful in balancing holes and electrons and in broadening recombination zone. In addition, the matched triplet energy of Eu(TTA)3phen is instrumental in facilitating energy transfer from host to emitter. Finally, highly efficient red EL devices with the highest current efficiency, power efficiency and brightness up to 58.98 cd A(-1) (external quantum efficiency (EQE) of 21%), 61.73 lm W(-1) and 100870 cd m(-2), respectively, were obtained by appropriately decreasing the doping concentration of iridium complex. At certain brightness of 1000 cd m(-2), EL current efficiency up to 51.94 cd A(-1) (EQE = 18.5%) was retained. Our investigation extends the application of rare earth complexes in EL devices and provides a chance to improve the device performances.

  15. Tuning steric and electronic effects in transition-metal β-diketiminate complexes

    PubMed Central

    Chen, Chi; Bellows, Sarina M.; Holland, Patrick L.

    2015-01-01

    β-Diketiminates are widely used supporting ligands for building a range of metal complexes with different oxidation states, structures, and reactivities. This Perspective summarizes the steric and electronic influences of ligand substituents on these complexes, with an eye toward informing the design of new complexes with optimized properties. The backbone and N-aryl substituents can give significant steric effects on structure, reactivity and selectivity of reactions. The electron density on the metal can be tuned by installation of electron withdrawing or donating groups on the β-diketiminate ligand as well. Examples are shown from throughout the transition metal series to demonstrate different types of effects attributable to systematic variation of β-diketiminate ligands. PMID:26244489

  16. Electron mobility of rare earth complexes measured by transient electroluminescence method

    NASA Astrophysics Data System (ADS)

    Zang, F. X.; Lengyel, O.; Li, Wenlian; Hong, Z. R.; Liu, Ze; Lee, C. S.; Lee, S. T.

    2006-09-01

    Electron mobility of gadolinium/europium (dibenzoylmethanato) 3(bathophenanthroline) (Gd/Eu(DBM) 3 bath) was measured by transient electroluminescence (EL) method. Although electron mobility of the two complexes were expected to be same, the value of mobility (1.2 × 10 -4 cm 2/Vs at electric field of 1 MV/cm) of Eu(DBM) 3 bath complex was bigger than that (8 × 10 -5 cm 2/Vs at electric field of 1 MV/cm) of Gd(DBM) 3 bath complex. It was found to be related to the different luminescent mechanisms of active materials and recombination zones in the devices. According to this, penetration length of hole injected into electron transport layer of Eu(DBM) 3 bath was estimated.

  17. Electron collisions with the CH2O-H2O complex

    NASA Astrophysics Data System (ADS)

    Freitas, T. C.; Lima, M. A. P.; Canuto, S.; Bettega, M. H. F.

    2009-12-01

    We report cross sections for elastic collisions of low-energy electrons with the CH2O-H2O complex. We employed the Schwinger multichannel method with pseudopotentials in the static-exchange and in the static-exchange-polarization approximations for energies from 0.1 to 20 eV. We considered four different hydrogen-bonded structures for the complex that were generated by classical Monte Carlo simulations. Our aim is to investigate the effect of the water molecule on the π∗ shape resonance of formaldehyde. Previous studies reported a π∗ shape resonance for CH2O at around 1 eV. The resonance positions of the complexes appear at lower energies in all cases due to the mutual polarization between the two molecules. This indicates that the presence of water may favor dissociation by electron impact and may lead to an important effect on strand breaking in wet DNA by electron impact.

  18. Crystal structure of an electron transfer complex between aromatic amine dehydrogenase and azurin from Alcaligenes faecalis.

    PubMed

    Sukumar, Narayanasami; Chen, Zhi-wei; Ferrari, Davide; Merli, Angelo; Rossi, Gian Luigi; Bellamy, Henry D; Chistoserdov, Andrei; Davidson, Victor L; Mathews, F Scott

    2006-11-14

    The crystal structure of an electron transfer complex of aromatic amine dehydrogenase (AADH) and azurin is presented. Electrons are transferred from the tryptophan tryptophylquinone (TTQ) cofactor of AADH to the type I copper of the cupredoxin azurin. This structure is compared with the complex of the TTQ-containing methylamine dehydrogenase (MADH) and the cupredoxin amicyanin. Despite significant similarities between the two quinoproteins and the two cupredoxins, each is specific for its respective partner and the ionic strength dependence and magnitude of the binding constant for each complex are quite different. The AADH-azurin interface is largely hydrophobic, covering approximately 500 A(2) of surface on each molecule, with one direct hydrogen bond linking them. The closest distance from TTQ to copper is 12.6 A compared with a distance of 9.3 A in the MADH-amicyanin complex. When the MADH-amicyanin complex is aligned with the AADH-azurin complex, the amicyanin lies on top of the azurin but is oriented quite differently. Although the copper atoms differ in position by approximately 4.7 A, the amicyanin bound to MADH appears to be rotated approximately 90 degrees from its aligned position with azurin. Comparison of the structures of the two complexes identifies features of the interface that dictate the specificity of the protein-protein interaction and determine the rate of interprotein electron transfer.

  19. Use of Ruthenium Photooxidation Techniques to Study Electron Transfer in the Cytochrome bc1 Complex

    PubMed Central

    Millett, Francis; Durham, Bill

    2009-01-01

    Ruthenium photooxidation methods are presented to study electron transfer between the cytochrome bc1 complex and cytochrome c, and within the cytochrome bc1 complex. Methods are described to prepare a ruthenium cytochrome c derivative, Ruz-39-Cc, by labeling the single sulfhydryl on yeast H39C;C102T iso-1-Cc with the reagent Ru(bpz)2(4-bromomethyl-4′-methylbipyridine). The ruthenium complex attached to Cys-39 on the opposite side of Cc from the heme crevice does not affect the interaction with cyt bc1. Laser excitation of reduced Ruz-39-Cc results in photooxidation of heme c within 1 μs with a yield of 20%. Flash photolysis of a 1:1 complex between reduced yeast cytochrome bc1 and Ruz-39-Cc leads to electron transfer from heme c1 to heme c with a rate constant of 1.4 × 104 s-1. Methods are described for the use of the ruthenium dimer, Ru2D, to photooxidize cyt c1 in the cytochrome bc1 complex within 1 μs with a yield of 20%. Electron transfer from the Rieske iron-sulfur center [2Fe2S] to cyt c1 was detected with a rate constant of 6 × 104 s-1 in R. sphaeroides cyt bc1 using this method. This electron transfer step is rate-limited by the rotation of the Rieske iron-sulfur protein in a conformational gating mechanism. This method provides critical information on the dynamics of rotation of the iron-sulfur protein (ISP) as it transfers electrons from QH2 in the Qo site to cyt c1 These ruthenium photooxidation methods can be used to measure many of the electron transfer reactions in cytochrome bc1 complexes from any source. PMID:19348884

  20. Geometric and Electronic Structure of a Peroxomanganese(III) Complex Supported by a Scorpionate Ligand

    PubMed Central

    Colmer, Hannah E.; Geiger, Robert A.; Leto, Domenick F.; Wijeratne, Gayan B.; Day, Victor W.; Jackson, Timothy A.

    2014-01-01

    A monomeric MnII complex has been prepared with the facially-coordinating TpPh2 ligand, (TpPh2 = hydrotris(3,5-diphenylpyrazol-1-yl)borate). The X-ray crystal structure shows three coordinating solvent molecules resulting in a six-coordinate complex with Mn-ligand bond lengths that are consistent with a high-spin MnII ion. Treatment of this MnII complex with excess KO2 at room temperature resulted in the formation of a MnIII-O2 complex that is stable for several days at ambient conditions, allowing for the determination of the X-ray crystal structure of this intermediate. The electronic structure of this peroxomanganese(III) adduct was examined by using electronic absorption, electron paramagnetic resonance (EPR), low-temperature magnetic circular dichroism (MCD), and variable-temperature variable-field (VTVH) MCD spectroscopies. Density functional theory (DFT), time-dependent (TD)-DFT, and multireference ab initio CASSCF/NEVPT2 calculations were used to assign the electronic transitions and further investigate the electronic structure of the peroxomanganese(III) species. The lowest ligand-field transition in the electronic absorption spectrum of the MnIII-O2 complex exhibits a blue shift in energy compared to other previously characterized peroxomanganese(III) complexes that results from a large axial bond elongation, reducing the metal-ligand covalency and stabilizing the σ-antibonding Mn dz2 MO that is the donor MO for this transition. PMID:25312785

  1. Electrostatic effects on proton coupled electron transfer in oxomanganese complexes inspired by the oxygen-evolving complex of photosystem II.

    PubMed

    Amin, Muhamed; Vogt, Leslie; Vassiliev, Serguei; Rivalta, Ivan; Sultan, Mohammad M; Bruce, Doug; Brudvig, Gary W; Batista, Victor S; Gunner, M R

    2013-05-23

    The influence of electrostatic interactions on the free energy of proton coupled electron transfer in biomimetic oxomanganese complexes inspired by the oxygen-evolving complex (OEC) of photosystem II (PSII) are investigated. The reported study introduces an enhanced multiconformer continuum electrostatics (MCCE) model, parametrized at the density functional theory (DFT) level with a classical valence model for the oxomanganese core. The calculated pKa's and oxidation midpoint potentials (E(m)'s) match experimental values for eight complexes, indicating that purely electrostatic contributions account for most of the observed couplings between deprotonation and oxidation state transitions. We focus on pKa's of terminal water ligands in [Mn(II/III)(H2O)6](2+/3+) (1), [Mn(III)(P)(H2O)2](3-) (2, P = 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphyrinato), [Mn2(IV,IV)(μ-O)2(terpy)2(H2O)2](4+) (3, terpy = 2,2':6',2″-terpyridine), and [Mn3(IV,IV,IV)(μ-O)4(phen)4(H2O)2](4+) (4, phen = 1,10-phenanthroline) and the pKa's of μ-oxo bridges and Mn E(m)'s in [Mn2(μ-O)2(bpy)4] (5, bpy = 2,2'-bipyridyl), [Mn2(μ-O)2(salpn)2] (6, salpn = N,N'-bis(salicylidene)-1,3-propanediamine), [Mn2(μ-O)2(3,5-di(Cl)-salpn)2] (7), and [Mn2(μ-O)2(3,5-di(NO2)-salpn)2] (8). The analysis of complexes 6-8 highlights the strong coupling between electron and proton transfers, with any Mn oxidation lowering the pKa of an oxo bridge by 10.5 ± 0.9 pH units. The model also accounts for changes in the E(m)'s by ligand substituents, such as found in complexes 6-8, due to the electron withdrawing Cl (7) and NO2 (8). The reported study provides the foundation for analysis of electrostatic effects in other oxomanganese complexes and metalloenzymes, where proton coupled electron transfer plays a fundamental role in redox-leveling mechanisms.

  2. Cyclic (Alkyl)(Amino)Carbene Complexes of Rhodium and Nickel and Their Steric and Electronic Parameters.

    PubMed

    Paul, Ursula S D; Sieck, Carolin; Haehnel, Martin; Hammond, Kai; Marder, Todd B; Radius, Udo

    2016-07-25

    N-heterocyclic carbenes (NHCs) and cyclic (alkyl)(amino)carbenes (CAACs) are of great interest, as their electronic and steric properties provide a unique class of ligands and organocatalysts. Herein, substitution reactions involving novel carbonyl complexes of rhodium and nickel were studied to provide a deeper understanding of the fundamental electronic factors characterizing CAAC(methyl) , which were compared with the large array of data available for NHC and sterically more demanding CAAC ligands.

  3. Formation of peptide radical ions through dissociative electron transfer in ternary metal-ligand-peptide complexes.

    PubMed

    Chu, Ivan K; Laskin, Julia

    2011-01-01

    The formation and fragmentation of odd-electron ions of peptides and proteins is of interest to applications in biological mass spectrometry. Gas-phase redox chemistry occurring during collision-induced dissociation of ternary metal-ligand-peptide complexes enables the formation of a variety of peptide radicals, including the canonical radical cations, M(+•), radical dications, [M+H](2+•), radical anions, [M-2H](-•) and phosphorylated radical cations. In addition, odd-electron peptide ions with well-defined initial location of the radical site are produced through side-chain losses from the radical ions. Subsequent fragmentation of these species provides information regarding the role of charge and location of the radical site on the competition between radical-induced and proton-driven fragmentation of odd-electron peptide ions. This account summarizes current understanding of the factors that control the efficiency of the intramolecular electron transfer (ET) in ternary metal-ligand-peptide complexes resulting in formation of odd-electron peptide ions. Specifically, we discuss the effect of the metal center, the ligand and the peptide structure on the competition between the ET, proton transfer (PT) and loss of neutral peptide and neutral peptide fragments from the complex. Fundamental studies of the structures, stabilities and the energetics and dynamics of fragmentation of these complexes are also important for detailed molecular-level understanding of photosynthesis and respiration in biological systems.

  4. Photoinduced electron transfer in a protein-surfactant complex: probing the interaction of SDS with BSA.

    PubMed

    Chakraborty, Anjan; Seth, Debabrata; Setua, Palash; Sarkar, Nilmoni

    2006-08-24

    Photoinduced fluorescence quenching electron transfer from N,N-dimethyl aniline to different 7-amino coumarin dyes has been investigated in sodium dodecyl sulfate (SDS) micelles and in bovine serum albumin (BSA)-SDS protein-surfactant complexes using steady state and picosecond time resolved fluorescence spectroscopy. The electron transfer rate has been found to be slower in BSA-SDS protein-surfactant complexes compared to that in SDS micelles. This observation has been explained with the help of the "necklace-and-bead" structure formed by the protein-surfactant complex due to coiling of protein molecules around the micelles. In the correlation of free energy change to the fluorescence quenching electron transfer rate, we have observed that coumarin 151 deviates from the normal Marcus region, showing retardation in the electron transfer rate at higher negative free energy region. We endeavored to establish that the retardation in the fluorescence quenching electron transfer rate for coumarin 151 at higher free energy region is a result of slower rotational relaxation and slower translational diffusion of coumarin 151 (C-151) compared to its analogues coumarin 152 and coumarin 481 in micelles and in protein-surfactant complexes. The slower rotational relaxation and translational diffusion of C-151 are supposed to be arising from the different location of coumarin 151 compared to coumarin 152 and coumarin 481.

  5. Effect of electronic versus print format and different reading resources on knowledge acquisition in the third-year medicine clerkship.

    PubMed

    DeZee, Kent J; Durning, Steven; Denton, G Dodd

    2005-01-01

    Many medical students have access to electronic and print resources. It is not known if the format or the choice of resources effects knowledge acquisition over an entire clerkship. To determine if the format (electronic or print) or choice of reading materials is associated with knowledge acquisition during the 3-year internal medicine clerkship. This was a prospective cohort study. During the last week of the clerkship, students took the National Board of Medical Examiners (NBME) exam and completed a survey ranking the reading materials used. One hundred and fourteen 3rd-year internal medicine clerkship students participated. The most commonly reported resources were UpToDate (99%), a review or question book (93%), and Harrison's Principles of Internal Medicine (82%). Multivariate analysis showed a significant beneficial effect of any use of Harrison's (linear regression, p < .04, absolute difference 3 points, SD = 1.4) on NBME score. The format of the most important resource-electronic (61%) or print (39%)-did not predict the NBME score, p > .80. The format (electronic or print) of resources did not appear to effect NBME score in the medicine clerkship. A secondary analysis showed the use of Harrison's textbook was associated with improved knowledge acquisition.

  6. Visualizing Macromolecular Complexes with In Situ Liquid Scanning Transmission Electron Microscopy

    SciTech Connect

    Evans, James E.; Jungjohann, K. L.; Wong, Peony C. K.; Chiu, Po-Lin; Dutrow, Gavin H.; Arslan, Ilke; Browning, Nigel D.

    2012-11-01

    A central focus of biological research is understanding the structure/function relationship of macromolecular protein complexes. Yet conventional transmission electron microscopy techniques are limited to static observations. Here we present the first direct images of purified macromolecular protein complexes using in situ liquid scanning transmission electron microscopy. Our results establish the capability of this technique for visualizing the interface between biology and nanotechnology with high fidelity while also probing the interactions of biomolecules within solution. This method represents an important advancement towards allowing future high-resolution observations of biological processes and conformational dynamics in real-time.

  7. Visualizing macromolecular complexes with in situ liquid scanning transmission electron microscopy.

    PubMed

    Evans, James E; Jungjohann, Katherine L; Wong, Peony C K; Chiu, Po-Lin; Dutrow, Gavin H; Arslan, Ilke; Browning, Nigel D

    2012-11-01

    A central focus of biological research is understanding the structure/function relationship of macromolecular protein complexes. Yet conventional transmission electron microscopy techniques are limited to static observations. Here we present the first direct images of purified macromolecular protein complexes using in situ liquid scanning transmission electron microscopy. Our results establish the capability of this technique for visualizing the interface between biology and nanotechnology with high fidelity while also probing the interactions of biomolecules within solution. This method represents an important advancement towards allowing future high-resolution observations of biological processes and conformational dynamics in real-time. Published by Elsevier Ltd.

  8. Electronic structure and spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide

    NASA Astrophysics Data System (ADS)

    Kharchenko, Valerii I.; Kurbatov, Ilya A.; Cherednichenko, Alexander I.; Mirochnik, Anatoly G.; Zhikhareva, Polina A.

    2017-03-01

    Spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide have been studied by quantum-chemical methods within the density functional theory and methods of luminescent and X-ray photoelectron spectroscopy. Analysis of the luminescence excitation spectrum of the complex has indicated the absence of intramolecular transfer of electronic excitation energy from the ligand levels to the resonance levels of the rare earth central ion, so luminescence of the complex is associated with the electronic f-f-transitions of Tb3 + ion (transitions 5D4 → 7FJ, J = 3-6). According to quantum-chemical modeling of the excited singlet and triplet levels of the complex, the excitation energy transfer from the ligands onto the central ion does not occur because of the significant difference of energies of their excited states.

  9. Electronic structure and spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide.

    PubMed

    Kharchenko, Valerii I; Kurbatov, Ilya A; Cherednichenko, Alexander I; Mirochnik, Anatoly G; Zhikhareva, Polina A

    2017-03-05

    Spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide have been studied by quantum-chemical methods within the density functional theory and methods of luminescent and X-ray photoelectron spectroscopy. Analysis of the luminescence excitation spectrum of the complex has indicated the absence of intramolecular transfer of electronic excitation energy from the ligand levels to the resonance levels of the rare earth central ion, so luminescence of the complex is associated with the electronic f-f-transitions of Tb(3+) ion (transitions (5)D4→(7)FJ, J=3-6). According to quantum-chemical modeling of the excited singlet and triplet levels of the complex, the excitation energy transfer from the ligands onto the central ion does not occur because of the significant difference of energies of their excited states.

  10. A general exit strategy of monoheme cytochromes c and c2 in electron transfer complexes?

    PubMed

    De March, Matteo; Brancatelli, Giovanna; Demitri, Nicola; De Zorzi, Rita; Hickey, Neal; Geremia, Silvano

    2015-09-01

    Using our previously reported maps of the electrostatic surface of horse heart ferri- and ferro-cyt c, comparisons were made between the complementary electrostatic surfaces of three cyt c peroxidase-cyt c complexes and the photosynthetic reaction center-cyt c complex, considering both iron oxidation states. The results obtained were consistent with a sliding mechanism for the electron shuttle on the surface of the protein complexes, promoted by the change in iron oxidation state. This mechanism was found to be in agreement with theoretical and NMR studies reported in the literature. Importantly, the analysis also provided a rationale for recognition of nonproductive associations. As we have previously reported the same conclusion on examination of redox partners of cyt c in the mitochondrial respiratory pathway, our hypothesis is that the proposed mechanism could represent a general exit strategy of monoheme cyts c and c2 in electron transfer complexes. © 2015 International Union of Biochemistry and Molecular Biology.

  11. Spectroscopic and Electronic Structure Studies of Phenolate Cu(II) Complexes

    PubMed Central

    Ghosh, Somdatta; Cirera, Jordi; Vance, Michael A.; Ono, Tetsuya; Fujisawa, Kiyoshi; Solomon, Edward I.

    2009-01-01

    A combination of spectroscopies and DFT calculations have been used to define the electronic structures of two crystallographically defined CuII-phenolate complexes. These complexes differ in the orientation of the phenolate ring which results in different bonding interactions of the phenolate donor orbitals with the CuII, which are reflected in the very different spectroscopic properties of the two complexes. These differences in electronic structures lead to significant differences in DFT calculated reactivities with oxygen. These calculations suggest that oxygen activation via a CuI phenoxyl ligand-to-metal charge transfer (LMCT) complex is highly endergonic (> 50 kcal/mol), hence an unlikely pathway. Rather, the two electron oxidation of the phenolate forming a bridging CuII peroxoquinone complex is more favorable (11.3 kcal/mol). The role of the oxidized metal in mediating this two electron oxidation of the coordinated phenolate and its relevance to the biogenesis of the covalently bound topa quinone in amine oxidase are discussed. PMID:18998639

  12. Data-driven planning of distributed energy resources amidst socio-technical complexities

    NASA Astrophysics Data System (ADS)

    Jain, Rishee K.; Qin, Junjie; Rajagopal, Ram

    2017-08-01

    New distributed energy resources (DER) are rapidly replacing centralized power generation due to their environmental, economic and resiliency benefits. Previous analyses of DER systems have been limited in their ability to account for socio-technical complexities, such as intermittent supply, heterogeneous demand and balance-of-system cost dynamics. Here we develop ReMatch, an interdisciplinary modelling framework, spanning engineering, consumer behaviour and data science, and apply it to 10,000 consumers in California, USA. Our results show that deploying DER would yield nearly a 50% reduction in the levelized cost of electricity (LCOE) over the status quo even after accounting for socio-technical complexities. We abstract a detailed matching of consumers to DER infrastructure from our results and discuss how this matching can facilitate the development of smart and targeted renewable energy policies, programmes and incentives. Our findings point to the large-scale economic and technical feasibility of DER and underscore the pertinent role DER can play in achieving sustainable energy goals.

  13. Electronic Structure of Transition Metal Clusters and Actinide Complexes and Their Reactivity

    SciTech Connect

    Balasubramanian, K

    2008-10-06

    Our research in this area since October 2007 has resulted in seven completed publications and more papers of the completed work are in progress. Our work during this period principally focused on actinide complexes with secondary emphasis on spectroscopic properties and electronic structure of metal complexes. As the publications are available online with all of the details of the results, tables and figures, we are providing here only a brief summary of major highlights, in each of the categories.

  14. Electronic structure and luminescence of tellurium (IV) halide complexes with guanidine and caesium cations

    NASA Astrophysics Data System (ADS)

    Dotsenko, A. A.; Shcheka, O. L.; Vovna, V. I.; Korochentsev, V. V.; Mirochnik, A. G.; Sedakova, T. V.

    2016-04-01

    The present paper continues a series of publications on the investigation of complex compounds of s2 ions and their properties. The structure of the valence levels of Cs2TeX6, (HGu)2TeCl6 complexes (where X = Cl, Br; HGu+ - guanidinium) is examined, the orbital nature of luminescence excitation is established, and the relationship of properties with the electronic structure is determined by means of X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT).

  15. Ultrafast events in the electron photodetachment from the hexacyanoferrate(II) complex in solution

    NASA Astrophysics Data System (ADS)

    Pommeret, Stanislas; Naskrecki, Ryszard; van der Meulen, Peter; Ménard, Marjorie; Vigneron, Georges; Gustavsson, Thomas

    1998-05-01

    Following excitation of the hexacyanoferrate(II) complex in water with a 40 fs laser pulse at 267 nm, the absorption of the hydrated electron rises with a global time constant of 510 fs, whereas the characteristic absorption of the hexacyanoferrate(III) appears almost instantaneously. A transient absorption band around 490 nm is tentatively assigned to the charge-transfer-to-solvent (CTTS) state of the hexacyanoferrate(II). Its ultra-rapid decay (≪60 fs) is due to the electronic repulsion between the electron and its parent core.

  16. SAGES: A Suite of Freely-Available Software Tools for Electronic Disease Surveillance in Resource-Limited Settings

    DTIC Science & Technology

    2011-05-10

    health resources, and the costs of proprietary software. The Suite for Automated Global Electronic bioSurveillance (SAGES) is a collection of modular...concert with existing surveillance applications or the SAGES tools may be used en masse for an end-to-end biosurveillance capability. This flexibility...the scope of reportable conditions and are intended to help prevent and respond to global public health threats. SAGES, an electronic biosurveillance

  17. Generation and accretion of electrons in complex plasmas with cylindrical particles

    SciTech Connect

    Sodha, Mahendra Singh; Misra, Shikha; Mishra, S. K.

    2009-12-15

    This paper presents an analytical model for the physical understanding of the charging of cylindrical dust particles in an open complex plasma system. Two different mechanisms, viz., thermionic emission and photoelectric emission have been considered for the electron generation from the charged cylindrical dust particles; the corresponding expressions for the rate of emission of electrons and their mean energy have been derived. A simple approach has been adopted to derive the expression for the rate of electron accretion to the dust particle. Further a new expression for the mean energy associated with the accreted electrons due to cylindrical dust particle has been derived and presented. An interesting comparison of results obtained in the case of spherical and cylindrical dust particles has also been made. Using these expressions, a formalism has been developed for the electronic processes in an illuminated dust cloud with cylindrical particles, on the basis of charge neutrality condition and number and energy balance of electrons; the charge carried by the cylindrical dust particles, electron temperature, and electron density corresponding to a given situation have been determined. The limitation of the applicability of the theory, viz., that the mean free path of an electron for accretion by dust particles be less than the dimension of the dust cloud has been pointed out.

  18. Modeling electron transfer thermodynamics in protein complexes: interaction between two cytochromes c(3).

    PubMed

    Teixeira, Vitor H; Baptista, António M; Soares, Cláudio M

    2004-05-01

    Redox protein complexes between type I and type II tetraheme cytochromes c(3) from Desulfovibrio vulgaris Hildenborough are here analyzed using theoretical methodologies. Various complexes were generated using rigid-body docking techniques, and the two lowest energy complexes (1 and 2) were relaxed using molecular dynamics simulations with explicit solvent and subjected to further characterization. Complex 1 corresponds to an interaction between hemes I from both cytochromes c(3). Complex 2 corresponds to an interaction between the heme IV from type I and the heme I from type II cytochrome c(3). Binding free energy calculations using molecular mechanics, Poisson-Boltzmann, and surface accessibility methods show that complex 2 is more stable than complex 1. Thermodynamic calculations on complex 2 show that complex formation induces changes in the reduction potential of both cytochromes c(3), but the changes are larger in the type I cytochrome c(3) (the largest one occurring on heme IV, of approximately 80 mV). These changes are sufficient to invert the global titration curves of both cytochromes, generating directionally in electron transfer from type I to type II cytochrome c(3), a phenomenon of obvious thermodynamic origin and consequences, but also with kinetic implications. The existence of processes like this occurring at complex formation may constitute a natural design of efficient redox chains.

  19. Coordination characteristics of uranyl BBP complexes: Insights from an electronic structure analysis

    DOE PAGES

    Pemmaraju, Chaitanya Das; Copping, Roy; Smiles, Danil E.; ...

    2017-03-21

    Here, organic ligand complexes of lanthanide/actinide ions have been studied extensively for applications in nuclear fuel storage and recycling. Several complexes of 2,6-bis(2-benzimidazyl)pyridine (H2BBP) featuring the uranyl moiety have been reported recently, and the present study investigates the coordination characteristics of these complexes using density functional theory-based electronic structure analysis. In particular, with the aid of several computational models, the nonplanar equatorial coordination about uranyl, observed in some of the compounds, is studied and its origin traced to steric effects.

  20. Electronic structure of the [MNH2]+ (M = Sc-Cu) complexes.

    PubMed

    Hendrickx, Marc F A; Clima, Sergiu

    2006-11-23

    B3LYP geometry optimizations for the [MNH2]+ complexes of the first-row transition metal cations (Sc+-Cu+) were performed. Without any exception the ground states of these unsaturated amide complexes were calculated to possess planar geometries. CASPT2 binding energies that were corrected for zero-point energies and including relativistic effects show a qualitative trend across the series that closely resembles the experimental observations. The electronic structures for the complexes of the early and middle transition metal cations (Sc+-Co+) differ from the electronic structures derived for the complexes of the late transition metal cations (Ni+ and Cu+). For the former complexes the relative higher position of the 3d orbitals above the singly occupied 2p(pi) HOMO of the uncoordinated NH2 induces an electron transfer from the 3d shell to 2p(pi). The stabilization of the 3d orbitals from the left to the right along the first-row transition metal series causes these orbitals to become situated below the HOMO of the NH2 ligand for Ni+ and Cu+, preventing a transfer from occurring in the [MNH2]+ complexes of these metal cations. Analysis of the low-lying states of the amide complexes revealed a rather unique characteristic of their electronic structures that was found across the entire series. Rather exceptionally for the whole of chemistry, pi-type interactions were calculated to be stronger than the corresponding sigma-type interactions. The origin of this extraordinary behavior can be ascribed to the low-lying sp2 lone pair orbital of the NH2 ligand with respect to the 3d level.

  1. Tidal energy resource complexity in a large strait: The Karori Rip, Cook Strait

    NASA Astrophysics Data System (ADS)

    Stevens, C. L.; Smith, M. J.; Grant, B.; Stewart, C. L.; Divett, T.

    2012-02-01

    Successful extraction of tidal stream energy will require a good understanding of flow at a range of scales, including those relating to average energy, variability in energy supply and fatigue. Current and turbulence measurements from the Karori Rip area of Cook Strait, the prime focal region of open-water tidal stream electricity generation in New Zealand, are described. A key issue is that a significant portion of the energy is contained in waters deeper than normally considered for energy extraction. Here we compare shallow and deep sites. Velocity data were derived from acoustic Doppler current profiler moorings, as well as spatial surveys and show flow magnitudes reaching 3.4 m s -1 in the shallow regions. The maximum speeds in both shallow and deep sites were typically located in the upper part of the measured water column although moored acoustic Doppler current profiler (ADCP) observations showed some complexity in this regard. Benthic boundary-layers were resolved in the bottom ˜20 m of the water column. Measured turbulent kinetic energy dissipation rates ɛ exceeded 10 -5 m 2 s -3 and estimated maximum ɛ is a factor of 10 greater. This was not distributed evenly through the water column, with stratification and velocity shear clearly persisting, especially around the turn of the tide. The implications for tidal stream energy are that (i) there is sufficient energy resource in the region for a moderate sized array of turbines, (ii) the vertical variability in the flow speed suggests turbines that can operate near the surface would be more effective at accessing the resource, (iii) stratification may persist and influence the scales of turbulence and (iv) wave-current interaction effects will influence any near-surface structure as well as vessel operations.

  2. Wind Resource Assessment in Complex Terrain with a High-Resolution Numerical Weather Prediction Model

    NASA Astrophysics Data System (ADS)

    Gruber, Karin; Serafin, Stefano; Grubišić, Vanda; Dorninger, Manfred; Zauner, Rudolf; Fink, Martin

    2014-05-01

    A crucial step in planning new wind farms is the estimation of the amount of wind energy that can be harvested in possible target sites. Wind resource assessment traditionally entails deployment of masts equipped for wind speed measurements at several heights for a reasonably long period of time. Simplified linear models of atmospheric flow are then used for a spatial extrapolation of point measurements to a wide area. While linear models have been successfully applied in the wind resource assessment in plains and offshore, their reliability in complex terrain is generally poor. This represents a major limitation to wind resource assessment in Austria, where high-altitude locations are being considered for new plant sites, given the higher frequency of sustained winds at such sites. The limitations of linear models stem from two key assumptions in their formulation, the neutral stratification and attached boundary-layer flow, both of which often break down in complex terrain. Consequently, an accurate modeling of near-surface flow over mountains requires the adoption of a NWP model with high horizontal and vertical resolution. This study explores the wind potential of a site in Styria in the North-Eastern Alps. The WRF model is used for simulations with a maximum horizontal resolution of 800 m. Three nested computational domains are defined, with the innermost one encompassing a stretch of the relatively broad Enns Valley, flanked by the main crest of the Alps in the south and the Nördliche Kalkalpen of similar height in the north. In addition to the simulation results, we use data from fourteen 10-m wind measurement sites (of which 7 are located within valleys and 5 near mountain tops) and from 2 masts with anemometers at several heights (at hillside locations) in an area of 1600 km2 around the target site. The potential for wind energy production is assessed using the mean wind speed and turbulence intensity at hub height. The capacity factor is also evaluated

  3. Fabrication of an Organic Light-Emitting Diode from New Host π Electron Rich Zinc Complex

    NASA Astrophysics Data System (ADS)

    Jafari, Mohammad Reza; Janghouri, Mohammad; Shahedi, Zahra

    2017-01-01

    A new π electron rich zinc complex was used as a fluorescent material in organic light-emitting diodes (OLEDs). Devices with a structure of indium tin oxide/poly (3,4-ethylenedi-oxythiophene):poly(styrenesulfonate) (PEDOT: PSS) (50 nm)/polyvinylcarbazole (60 nm)/Zn: %2 porphyrin derivatives (45 nm)/Al (150 nm) were fabricated. Porphyrin derivatives accounting for 2 wt.% in the π electron rich zinc complex were used as a host. The electroluminescence (EL) spectra of porphyrin derivatives indicated a red shift, as π electron rich zinc complex EL spectra. The device (4) has also a luminance of 3420 cd/m2 and maximum efficiency of 1.58 cd/A at 15 V, which are the highest values among four devices. The result of Commission International del'Eclairage (CIE) (X, Y) coordinate and EL spectrum of device (3) indicated that it is more red shifted compared to other devices. Results of this work indicate that π electron rich zinc complex is a promising host material for high efficiency red OLEDs and has a simple structure compared to Alq3-based devices.

  4. Principles of the electronic structure of complexes of non-transition elements

    NASA Astrophysics Data System (ADS)

    Kostikova, Galina P.; Korol'kov, Dimitrii V.; Kostikov, Yury P.

    1997-04-01

    The results of quantum-chemical calculations of electronic structures of complexes of non-transition elements are surveyed. Their X-ray emission and X-ray photoelectron spectra are analysed. General principles of the electronic structure of these complexes are established. It is shown that the effective participation of partially or completely occupied valence npm orbitals of the central atom A of ALk complexes in the formation of delocalised MOs, the negligibly small contribution of vacant And orbitals to the bonds with ligands, the valence inertness or rather low contribution of occupied Ans2 orbitals (except for 2s2 AO) to the valence MOs, and the initiation of the multiple bonds (in the electronic structure of complexes) due to covalent or hypervalent π-interactions involving only 2p (but not 3p, 4p, etc.) atomic orbitals are the most significant factors influencing the electronic structure of non-transition element compounds. The concept of d orbitals and hypervalent bonds is critisised. The bibliography includes 130 references.

  5. Simple relationship between oxidation state and electron affinity in gas-phase metal-oxo complexes.

    PubMed

    Waller, Sarah E; Ray, Manisha; Yoder, Bruce L; Jarrold, Caroline Chick

    2013-12-19

    The photoelectron spectra of WO3H(-) and WO2F(-) are presented and analyzed in the context of a series of previous similar measurements on MO(y)(-) (M = Mo, W; y = 0-3), MO4H(-) and AlMOy(-) (y ≤ 4) complexes. The electronic structures of the WO3H and WO2F anion and neutral complexes were investigated using the B3LYP hybrid density functional method. The spectra of WO3H(-), WO2F(-), and previously measured AlWO3(-) photoelectron spectra show that the corresponding neutrals, in which the transition metal centers are all in a +5 oxidation state, have comparable electron affinities. In addition, the electron affinities fit the general trend of monotonically increasing electron affinity with oxidation state, in spite of the WO3H(-), WO2F(-), and AlWO3(-) having closed shell ground states, suggesting that the oxidation state of the metal atom has more influence than shell closing on the electron affinity of these transition metal-oxo complexes. Results of DFT calculations suggest that the neutrals are pyramidal and the anions are planar. However, the barriers for inversion on the neutral surface are low, and attempts to generate simple Franck-Condon simulations based on simple normal coordinate displacement, ignoring the effects of inversion, are inadequate.

  6. Charge transfer in the electron donor-acceptor complex BH3NH3.

    PubMed

    Mo, Yirong; Song, Lingchun; Wu, Wei; Zhang, Qianer

    2004-03-31

    As a simple yet strongly binding electron donor-acceptor (EDA) complex, BH(3)NH(3) serves as a good example to study the electron pair donor-acceptor complexes. We employed both the ab initio valence bond (VB) and block-localized wave function (BLW) methods to explore the electron transfer from NH(3) to BH(3). Conventionally, EDA complexes have been described by two diabatic states: one neutral state and one ionic charge-transferred state. Ab initio VB self-consistent field (VBSCF) computations generate the energy profiles of the two diabatic states together with the adiabatic (ground) state. Our calculations evidently demonstrated that the electron transfer between NH(3) and BH(3) falls in the abnormal regime where the reorganization energy is less than the exoergicity of the reaction. The nature of the NH(3)-BH(3) interaction is probed by an energy decomposition scheme based on the BLW method. We found that the variation of the charge-transfer energy with the donor-acceptor distance is insensitive to the computation levels and basis sets, but the estimation of the amount of electron transferred heavily depends on the population analysis procedures. The recent resurgence of interest in the nature of the rotation barrier in ethane prompted us to analyze the conformational change of BH(3)NH(3), which is an isoelectronic system with ethane. We found that the preference of the staggered structure over the eclipsed structure of BH(3)NH(3) is dominated by the Pauli exchange repulsion.

  7. Photoelectron spectroscopy of hexachloroplatinate-nucleobase complexes: Nucleobase excited state decay observed via delayed electron emission

    SciTech Connect

    Sen, Ananya; Matthews, Edward M.; Dessent, Caroline E. H. E-mail: xuebin.wang@pnnl.gov; Hou, Gao-Lei; Wang, Xue-Bin E-mail: xuebin.wang@pnnl.gov

    2015-11-14

    We report low-temperature photoelectron spectra of isolated gas-phase complexes of the hexachloroplatinate dianion bound to the nucleobases uracil, thymine, cytosine, and adenine. The spectra display well-resolved, distinct peaks that are consistent with complexes where the hexachloroplatinate dianion is largely intact. Adiabatic electron detachment energies for the hexachloroplatinate-nucleobase complexes are measured as 2.26-2.36 eV. The magnitudes of the repulsive Coulomb barriers (RCBs) of the complexes are all ∼1.7 eV, values that are lower than the RCB of the uncomplexed PtCl{sub 6}{sup 2−} dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photoelectron spectra of the four clusters. The 266 nm spectra of the PtCl{sub 6}{sup 2−} ⋅ thymine and PtCl{sub 6}{sup 2−} ⋅ adenine complexes also display very prominent delayed electron emission bands. These results mirror recent results on the related Pt(CN){sub 4}{sup 2−} ⋅ nucleobase complexes [A. Sen et al., J. Phys. Chem. B 119, 11626 (2015)]. The observation of delayed electron emission bands in the PtCl{sub 6}{sup 2−} ⋅ nucleobase spectra obtained in this work, as for the previously studied Pt(CN){sub 4}{sup 2−} ⋅ nucleobase complexes, is attributed to one-photon excitation of nucleobase-centred excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment. Moreover, the selective, strong excitation of the delayed emission bands in the 266 nm spectra is linked to fundamental differences in the individual nucleobase photophysics at this excitation energy. This strongly supports our previous suggestion that the dianion within these clusters can be viewed as a “dynamic tag” which has the propensity to emit electrons when the attached nucleobase decays over a time scale long enough to

  8. Effect of the complexation on the NLO electronic contribution in film based conjugated quinoline ligand

    NASA Astrophysics Data System (ADS)

    Arroudj, S.; Aamoum, A.; Messaadia, L.; Bouraiou, A.; Bouacida, S.; Bouchouit, K.; Sahraoui, B.

    2017-07-01

    In this paper we present the complexation, single crystal structure and the third harmonic generation response of the quinoline ligand and its mercury complex. Crystals structure of Bis(quinoline) Mercury (II) dichloride, (C18H14Cl2HgN2) is obtained from aqueous solution and characterized by single crystal X-ray diffraction at room temperature. This complex crystallizes in centrosymmetric space group. The structure is formed by chains along c axis. These chains are constituted by the quinoline ligand. The electronic contribution χTHG < 3 > is measured using the third harmonic generation technique on thin films at 1064 nm for quinoline ligand and its mercury complex incorporated in PMMA matrices. The first hyperpolarizability (β), the polarizability (α) and the electric dipole moment (μ) were calculated using the density functional B3LYP method with the LANL2DZ basis set. The obtained results for the quinoline ligand and its Hg complex show non zero (β).

  9. Accurate electronic-structure description of Mn complexes: a GGA+U approach

    NASA Astrophysics Data System (ADS)

    Li, Elise Y.; Kulik, Heather; Marzari, Nicola

    2008-03-01

    Conventional density-functional approach often fail in offering an accurate description of the spin-resolved energetics in transition metals complexes. We will focus here on Mn complexes, where many aspects of the molecular structure and the reaction mechanisms are still unresolved - most notably in the oxygen-evolving complex (OEC) of photosystem II and the manganese catalase (MC). We apply a self-consistent GGA + U approach [1], originally designed within the DFT framework for the treatment of strongly correlated materials, to describe the geometry, the electronic and the magnetic properties of various manganese oxide complexes, finding very good agreement with higher-order ab-initio calculations. In particular, the different oxidation states of dinuclear systems containing the [Mn2O2]^n+ (n= 2, 3, 4) core are investigated, in order to mimic the basic face unit of the OEC complex. [1]. H. J. Kulik, M. Cococcioni, D. A. Scherlis, N. Marzari, Phys. Rev. Lett., 2006, 97, 103001

  10. Spatial Complexity Due to Bulk Electronic Liquid Crystals in Superconducting Dy-Bi2212

    NASA Astrophysics Data System (ADS)

    Carlson, Erica; Phillabaum, Benjamin; Dahmen, Karin

    2012-02-01

    Surface probes such as scanning tunneling microscopy (STM) have detected complex electronic patterns at the nanoscale in many high temperature superconductors. In cuprates, the pattern formation is associated with the pseudogap phase, a precursor to the high temperature superconducting state. Rotational symmetry breaking of the host crystal (i.e. from C4 to C2) in the form of electronic nematicity has recently been proposed as a unifying theme of the pseudogap phase [Lawler Nature 2010]. However, the fundamental physics governing the nanoscale pattern formation has not yet been identified. Here we use universal cluster properties extracted from STM studies of cuprate superconductors to identify the funda- mental physics controlling the complex pattern formation. We find that due to a delicate balance between disorder, interactions, and material anisotropy, the rotational symmetry breaking is fractal in nature, and that the electronic liquid crystal extends throughout the bulk of the material.

  11. Utilization of Electronic Information Resources by Undergraduate Students of University of Ibadan: A Case Study of Social Sciences and Education

    ERIC Educational Resources Information Center

    Owolabi, Sola; Idowu, Oluwafemi A.; Okocha, Foluke; Ogundare, Atinuke Omotayo

    2016-01-01

    The study evaluated utilization of electronic information resources by undergraduates in the Faculties of Education and the Social Sciences in University of Ibadan. The study adopted a descriptive survey design with a study population of 1872 undergraduates in the Faculties of Education and the Social Sciences in University of Ibadan, from which a…

  12. True Serials: A True Solution for Electronic Resource Management Needs in a Medium-Size Academic Library

    ERIC Educational Resources Information Center

    Milczarski, Vivian; Garofalo, Denise A.

    2011-01-01

    A desire for more functionality seemed to clash with the fiscal reality of limited funds, but after investigating alternatives, Mount Saint Mary College was able to provide its faculty and students with a more useful and function-rich electronic resource management through a move to a hosted open source service. (Contains 8 figures.)

  13. True Serials: A True Solution for Electronic Resource Management Needs in a Medium-Size Academic Library

    ERIC Educational Resources Information Center

    Milczarski, Vivian; Garofalo, Denise A.

    2011-01-01

    A desire for more functionality seemed to clash with the fiscal reality of limited funds, but after investigating alternatives, Mount Saint Mary College was able to provide its faculty and students with a more useful and function-rich electronic resource management through a move to a hosted open source service. (Contains 8 figures.)

  14. Impact of Electronic Resources and Usage in Academic Libraries in Ghana: Evidence from Koforidua Polytechnic & All Nations University College, Ghana

    ERIC Educational Resources Information Center

    Akussah, Maxwell; Asante, Edward; Adu-Sarkodee, Rosemary

    2015-01-01

    The study investigates the relationship between impact of electronic resources and its usage in academic libraries in Ghana: evidence from Koforidua Polytechnic & All Nations University College, Ghana. The study was a quantitative approach using questionnaire to gather data and information. A valid response rate of 58.5% was assumed. SPSS…

  15. Architecture of complex I and its implications for electron transfer and proton pumping.

    PubMed

    Zickermann, Volker; Kerscher, Stefan; Zwicker, Klaus; Tocilescu, Maja A; Radermacher, Michael; Brandt, Ulrich

    2009-06-01

    Proton pumping NADH:ubiquinone oxidoreductase (complex I) is the largest and remains by far the least understood enzyme complex of the respiratory chain. It consists of a peripheral arm harbouring all known redox active prosthetic groups and a membrane arm with a yet unknown number of proton translocation sites. The ubiquinone reduction site close to iron-sulfur cluster N2 at the interface of the 49-kDa and PSST subunits has been mapped by extensive site directed mutagenesis. Independent lines of evidence identified electron transfer events during reduction of ubiquinone to be associated with the potential drop that generates the full driving force for proton translocation with a 4H(+)/2e(-) stoichiometry. Electron microscopic analysis of immuno-labelled native enzyme and of a subcomplex lacking the electron input module indicated a distance of 35-60 A of cluster N2 to the membrane surface. Resolution of the membrane arm into subcomplexes showed that even the distal part harbours subunits that are prime candidates to participate in proton translocation because they are homologous to sodium/proton antiporters and contain conserved charged residues in predicted transmembrane helices. The mechanism of redox linked proton translocation by complex I is largely unknown but has to include steps where energy is transmitted over extremely long distances. In this review we compile the available structural information on complex I and discuss implications for complex I function.

  16. Correlation between oxygen adsorption energy and electronic structure of transition metal macrocyclic complexes.

    PubMed

    Liu, Kexi; Lei, Yinkai; Wang, Guofeng

    2013-11-28

    Oxygen adsorption energy is directly relevant to the catalytic activity of electrocatalysts for oxygen reduction reaction (ORR). In this study, we established the correlation between the O2 adsorption energy and the electronic structure of transition metal macrocyclic complexes which exhibit activity for ORR. To this end, we have predicted the molecular and electronic structures of a series of transition metal macrocyclic complexes with planar N4 chelation, as well as the molecular and electronic structures for the O2 adsorption on these macrocyclic molecules, using the density functional theory calculation method. We found that the calculated adsorption energy of O2 on the transition metal macrocyclic complexes was linearly related to the average position (relative to the lowest unoccupied molecular orbital of the macrocyclic complexes) of the non-bonding d orbitals (d(z(2)), d(xy), d(xz), and d(yz)) which belong to the central transition metal atom. Importantly, our results suggest that varying the energy level of the non-bonding d orbitals through changing the central transition metal atom and/or peripheral ligand groups could be an effective way to tuning their O2 adsorption energy for enhancing the ORR activity of transition metal macrocyclic complex catalysts.

  17. Correlation between oxygen adsorption energy and electronic structure of transition metal macrocyclic complexes

    SciTech Connect

    Liu, Kexi; Lei, Yinkai; Wang, Guofeng

    2013-11-28

    Oxygen adsorption energy is directly relevant to the catalytic activity of electrocatalysts for oxygen reduction reaction (ORR). In this study, we established the correlation between the O{sub 2} adsorption energy and the electronic structure of transition metal macrocyclic complexes which exhibit activity for ORR. To this end, we have predicted the molecular and electronic structures of a series of transition metal macrocyclic complexes with planar N{sub 4} chelation, as well as the molecular and electronic structures for the O{sub 2} adsorption on these macrocyclic molecules, using the density functional theory calculation method. We found that the calculated adsorption energy of O{sub 2} on the transition metal macrocyclic complexes was linearly related to the average position (relative to the lowest unoccupied molecular orbital of the macrocyclic complexes) of the non-bonding d orbitals (d{sub z{sup 2}}, d{sub xy}, d{sub xz}, and d{sub yz}) which belong to the central transition metal atom. Importantly, our results suggest that varying the energy level of the non-bonding d orbitals through changing the central transition metal atom and/or peripheral ligand groups could be an effective way to tuning their O{sub 2} adsorption energy for enhancing the ORR activity of transition metal macrocyclic complex catalysts.

  18. Architecture of complex I and its implications for electron transfer and proton pumping

    PubMed Central

    Zickermann, Volker; Kerscher, Stefan; Zwicker, Klaus; Tocilescu, Maja A.; Radermacher, Michael; Brandt, Ulrich

    2009-01-01

    Proton pumping NADH:ubiquinone oxidoreductase (complex I) is the largest and remains by far the least understood enzyme complex of the respiratory chain. It consists of a peripheral arm harbouring all known redox active prosthetic groups and a membrane arm with a yet unknown number of proton translocation sites. The ubiquinone reduction site close to iron-sulfur cluster N2 at the interface of the 49-kDa and PSST subunits has been mapped by extensive site directed mutagenesis. Independent lines of evidence identified electron transfer events during reduction of ubiquinone to be associated with the potential drop that generates the full driving force for proton translocation with a 4 H+/2e− stoichiometry. Electron microscopic analysis of immuno-labelled native enzyme and of a subcomplex lacking the electron input module indicated a distance of 35–60 Å of cluster N2 to the membrane surface. Resolution of the membrane arm into subcomplexes showed that even the distal part harbours subunits that are prime candidates to participate in proton translocation because they are homologous to sodium/proton antiporters and contain conserved charged residues in predicted transmembrane helices. The mechanism of redox linked proton translocation by complex I is largely unknown but has to include steps where energy is transmitted over extremely long distances. In this review we compile the available structural information on complex I and discuss implications for complex I function. PMID:19366614

  19. Correlation between oxygen adsorption energy and electronic structure of transition metal macrocyclic complexes

    NASA Astrophysics Data System (ADS)

    Liu, Kexi; Lei, Yinkai; Wang, Guofeng

    2013-11-01

    Oxygen adsorption energy is directly relevant to the catalytic activity of electrocatalysts for oxygen reduction reaction (ORR). In this study, we established the correlation between the O2 adsorption energy and the electronic structure of transition metal macrocyclic complexes which exhibit activity for ORR. To this end, we have predicted the molecular and electronic structures of a series of transition metal macrocyclic complexes with planar N4 chelation, as well as the molecular and electronic structures for the O2 adsorption on these macrocyclic molecules, using the density functional theory calculation method. We found that the calculated adsorption energy of O2 on the transition metal macrocyclic complexes was linearly related to the average position (relative to the lowest unoccupied molecular orbital of the macrocyclic complexes) of the non-bonding d orbitals (d_{z^2 }, d_{xy}, d_{xz}, and dyz) which belong to the central transition metal atom. Importantly, our results suggest that varying the energy level of the non-bonding d orbitals through changing the central transition metal atom and/or peripheral ligand groups could be an effective way to tuning their O2 adsorption energy for enhancing the ORR activity of transition metal macrocyclic complex catalysts.

  20. Electron tunneling rates in respiratory complex I are tuned for efficient energy conversion.

    PubMed

    de Vries, Simon; Dörner, Katerina; Strampraad, Marc J F; Friedrich, Thorsten

    2015-02-23

    Respiratory complex I converts the free energy of ubiquinone reduction by NADH into a proton motive force, a redox reaction catalyzed by flavin mononucleotide(FMN) and a chain of seven iron-sulfur centers. Electron transfer rates between the centers were determined by ultrafast freeze-quenching and analysis by EPR and UV/Vis spectroscopy. The complex rapidly oxidizes three NADH molecules. The electron-tunneling rate between the most distant centers in the middle of the chain depends on the redox state of center N2 at the end of the chain, and is sixfold slower when N2 is reduced. The conformational changes that accompany reduction of N2 decrease the electronic coupling of the longest electron-tunneling step. The chain of iron-sulfur centers is not just a simple electron-conducting wire; it regulates the electron-tunneling rate synchronizing it with conformation-mediated proton pumping, enabling efficient energy conversion. Synchronization of rates is a principle means of enhancing the specificity of enzymatic reactions. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

  1. Managing complex research datasets using electronic tools: A meta-analysis exemplar

    PubMed Central

    Brown, Sharon A.; Martin, Ellen E.; Garcia, Theresa J.; Winter, Mary A.; García, Alexandra A.; Brown, Adama; Cuevas, Heather E.; Sumlin, Lisa L.

    2013-01-01

    Meta-analyses of broad scope and complexity require investigators to organize many study documents and manage communication among several research staff. Commercially available electronic tools, e.g., EndNote, Adobe Acrobat Pro, Blackboard, Excel, and IBM SPSS Statistics (SPSS), are useful for organizing and tracking the meta-analytic process, as well as enhancing communication among research team members. The purpose of this paper is to describe the electronic processes we designed, using commercially available software, for an extensive quantitative model-testing meta-analysis we are conducting. Specific electronic tools improved the efficiency of (a) locating and screening studies, (b) screening and organizing studies and other project documents, (c) extracting data from primary studies, (d) checking data accuracy and analyses, and (e) communication among team members. The major limitation in designing and implementing a fully electronic system for meta-analysis was the requisite upfront time to: decide on which electronic tools to use, determine how these tools would be employed, develop clear guidelines for their use, and train members of the research team. The electronic process described here has been useful in streamlining the process of conducting this complex meta-analysis and enhancing communication and sharing documents among research team members. PMID:23681256

  2. Managing complex research datasets using electronic tools: a meta-analysis exemplar.

    PubMed

    Brown, Sharon A; Martin, Ellen E; Garcia, Theresa J; Winter, Mary A; García, Alexandra A; Brown, Adama; Cuevas, Heather E; Sumlin, Lisa L

    2013-06-01

    Meta-analyses of broad scope and complexity require investigators to organize many study documents and manage communication among several research staff. Commercially available electronic tools, for example, EndNote, Adobe Acrobat Pro, Blackboard, Excel, and IBM SPSS Statistics (SPSS), are useful for organizing and tracking the meta-analytic process as well as enhancing communication among research team members. The purpose of this article is to describe the electronic processes designed, using commercially available software, for an extensive, quantitative model-testing meta-analysis. Specific electronic tools improved the efficiency of (a) locating and screening studies, (b) screening and organizing studies and other project documents, (c) extracting data from primary studies, (d) checking data accuracy and analyses, and (e) communication among team members. The major limitation in designing and implementing a fully electronic system for meta-analysis was the requisite upfront time to decide on which electronic tools to use, determine how these tools would be used, develop clear guidelines for their use, and train members of the research team. The electronic process described here has been useful in streamlining the process of conducting this complex meta-analysis and enhancing communication and sharing documents among research team members.

  3. Preparation and spectroscopic studies on charge-transfer complexes of 2-hydroxypyridine with electron acceptors

    NASA Astrophysics Data System (ADS)

    Gaballa, Akmal S.

    2013-07-01

    The CT-interactions of electron acceptors such as iodine (I2), chloranilic acid (H2CA) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) with 2-hydroxypyridine (HPyO) have been investigated in the defined solvent. The data indicate the formation of CT-complexes with the general formula [(HPyO)(acceptor)]. The 1:1 stoichiometry of the (HPyO)-acceptors were based on elemental analysis, IR spectra and thermogravimetric analysis of the solid CT-complexes along with the photometric titration measurements for the reactions. The formation constants (KCT) for the CT-complexes are shown to be strongly dependent on the type and structure of the electron acceptors. Factors affecting the CT-processes are discussed.

  4. Preparation and spectroscopic studies on charge-transfer complexes of famciclovir drug with different electron acceptors

    NASA Astrophysics Data System (ADS)

    Gaballa, Akmal S.; Teleb, Said M.; Nour, El-Metwally

    2012-09-01

    The CT-interaction of electron acceptors such as chloranilic acid (H2CA), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and and 7,7',8,8'-tetracyano-p-quinodimethane (TCNQ) with the antiviral drug famciclovir (FCV) have been investigated spectrophotometrically in the defined solvent. The data indicate the formation of CT-complexes with the general formula [(FCV)(acceptor)]. The 1:1 stoichiometry of the (FCV)-acceptors were based on elemental analysis, IR spectra and thermogravimetric analysis of the solid CT-complexes along with the photometric titration measurements for the reactions. The formation constants (KCT) for the CT-complexes are shown to be strongly dependent on the type and structure of the electron acceptor. Factors affecting the CT-processes such as redox potentials and steric hinderance of reactants are discussed.

  5. Coupling of Spin and Charge Ordering and Elastic Finescales in Complex Electronic Materials

    NASA Astrophysics Data System (ADS)

    Lookman, T.; Saxena, A.; Albers, R. C.; Bishop, A. R.; Shenoy, S. R.

    2000-03-01

    There has been an intense focus in the past decade on complex electronic/magnetic materials such as high temperature cuprate and bismuthate superconductors, colossal magnetoresistance manganites, martensitic (and shape memory) alloys, ferroelectric as well as relaxor titanates and zirconates. Various high-resolution microscopies probing spin, charge and lattice degrees of freedom have revealed new, intrinsically inhomogeneous phases, with complex multiscale patterning over hundreds of lattice spacings. We show that long-range anisotropic strain interactions arising from general elastic compatibility considerations, linking components of the strain tensor, can enable interfaces or atomic-scale defects, to induce global strain textures. Symmetry-allowed couplings between strains and electronic/magnetic variables can then generate effective strain-mediated long-range interactions between these variables. This provides a generic elastic mechanism for mutual multiscale texturing of spin, charge and microstructural variables in the above complex materials.

  6. Electron transfer reactions of osmium(II) complexes with phenols and phenolic acids

    NASA Astrophysics Data System (ADS)

    Rajeswari, Angusamy; Ramdass, Arumugam; Muthu Mareeswaran, Paulpandian; Velayudham, Murugesan; Rajagopal, Seenivasan

    2016-07-01

    Three [Os(NN)3]2+ complexes (NN = polypyridine) with ligands of varying hydrophobicity were synthesized and characterized by NMR spectral techniques. The geometry of the molecules are optimized by DFT calculations. The interaction between [Os(NN)3]2+ complexes and phenolate ion in ground state is confirmed by absorption spectral study and the binding constant values are in the range of 3-740 M-1. The photoinduced electron transfer reaction of these [Os(NN)3]2+ complexes with phenols and phenolic acids at pH 12.5 leads to the formation of phenoxyl radical confirmed through transient absorption spectral study. Binding constants and electron transfer rate constants within the [Os(NN)3]2+-phenolate ion adduct account for the change for the overall quenching constant with the change of structure of reactants.

  7. (Comparison of group transfer, inner sphere and outer sphere electron transfer mechanisms of organometallic complexes)

    SciTech Connect

    Atwood, J.

    1990-01-01

    During the course of Grant ER13775 we have constructed an infrared stopped-flow spectrophotometer and initiated a study of the mechanisms of reactions that involve a change in the oxidation state of organometallic complexes. The spectrometer combined conventional stopped-flow techniques with an infrared optical system comprised of a carbon monoxide laser, an IRTRAN flow-through cell and a mercury-cadium-telluride detector. In this summary we will highlight our results on reactions: (1) that formally involve exchange of a charged species between two metal carbonyl anions, (2) that involve additional of an electron to, or removal of an electron from organometallic complexes that contain a metal-metal bond, and (3) between coordination complexes and metal carbonyl anions. 12 refs.

  8. Does Leisure Time as a Stress Coping Resource Increase Affective Complexity? Applying the Dynamic Model of Affect (DMA)

    PubMed Central

    Qian, Xinyi (Lisa); Yarnal, Careen M.; Almeida, David M.

    2013-01-01

    Affective complexity, a manifestation of psychological well-being, refers to the relative independence between positive and negative affect (PA, NA). According to the Dynamic Model of Affect (DMA), stressful situations lead to highly inverse PA-NA relationship, reducing affective complexity. Meanwhile, positive events can sustain affective complexity by restoring PA-NA independence. Leisure, a type of positive events, has been identified as a coping resource. This study used the DMA to assess whether leisure time helps restore affective complexity on stressful days. We found that on days with more leisure time than usual, an individual experienced less negative PA-NA relationship after daily stressful events. The finding demonstrates the value of leisure time as a coping resource and the DMA’s contribution to coping research. PMID:24659826

  9. A major light rare-earth element (LREE) resource in the Khanneshin carbonatite complex, southern Afghanistan

    USGS Publications Warehouse

    Tucker, Robert D.; Belkin, Harvey E.; Schulz, Klaus J.; Peters, Stephen G.; Horton, Forrest; Buttleman, Kim; Scott, Emily R.

    2012-01-01

    The rapid rise in world demand for the rare-earth elements (REEs) has expanded the search for new REE resources. We document two types of light rare-earth element (LREE)-enriched rocks in the Khanneshin carbonatite complex of southern Afghanistan: type 1 concordant seams of khanneshite-(Ce), synchysite-(Ce), and parisite-(Ce) within banded barite-strontianite alvikite, and type 2 igneous dikes of coarse-grained carbonatite, enriched in fluorine or phosphorus, containing idiomorphic crystals of khanneshite-(Ce) or carbocernaite. Type 1 mineralized barite-strontianite alvikite averages 22.25 wt % BaO, 4.27 wt % SrO, and 3.25 wt % ∑ LREE2O3 (sum of La, Ce, Pr, and Nd oxides). Type 2 igneous dikes average 14.51 wt % BaO, 5.96 wt % SrO, and 3.77 wt % ∑ LREE2O3. A magmatic origin is clearly indicated for the type 2 LREE-enriched dikes, and type 1 LREE mineralization probably formed in the presence of LREE-rich hydrothermal fluid. Both types of LREE mineralization may be penecontemporaneous, having formed in a carbonate-rich magma in the marginal zone of the central vent, highly charged with volatile constituents (i.e., CO2, F, P2O5), and strongly enriched in Ba, Sr, and the LREE. Based on several assumptions, and employing simple geometry for the zone of LREE enrichment, we estimate that at least 1.29 Mt (million metric tonnes) of LREE2O3 is present in this part of the Khanneshin carbonatite complex.

  10. Framework for Smart Electronic Health Record- Linked Predictive Models to Optimize Care for Complex Digestive Diseases

    DTIC Science & Technology

    2015-03-01

    was to search our world-wide military medical record for data sets to develop Bayesian Network ( BN ) models to predict defined outcomes in Crohn’s...on the AP and CD cohorts to develop our BN predictive models. More specifically, creating and testing Bayesian Network models for AP and setting...clinical EMR as an effective tool for future research, resource allocation and planning with regard to complex chronic illnesses. Application of BN

  11. MONITORING AND ASSESSING THE CONDITION OF AQUATIC RESOURCES: ROLE OF COMPLEX SURVEY DESIGN AND ANALYSIS

    EPA Science Inventory

    The National Water Quality Monitoring Council (NWQMC) developed a common framework for aquatic resource monitoring. The framework is described in a series of articles published in Water Resources IMPACT, September, 2003. One objective of the framework is to encourage consistenc...

  12. Concerted proton-coupled electron transfer from a metal-hydride complex.

    PubMed

    Bourrez, Marc; Steinmetz, Romain; Ott, Sascha; Gloaguen, Frederic; Hammarström, Leif

    2014-02-01

    Metal hydrides are key intermediates in the catalytic reduction of protons and CO2 as well as in the oxidation of H2. In these reactions, electrons and protons are transferred to or from separate acceptors or donors in bidirectional protoncoupled electron transfer (PCET) steps. The mechanistic interpretation of PCET reactions of metal hydrides has focused on the stepwise transfer of electrons and protons. A concerted transfer may, however, occur with a lower reaction barrier and therefore proceed at higher catalytic rates. Here we investigate the feasibility of such a reaction by studying the oxidation–deprotonation reactions of a tungsten hydride complex. The rate dependence on the driving force for both electron transfer and proton transfer—employing different combinations of oxidants and bases—was used to establish experimentally the concerted, bidirectional PCET of a metal-hydride species. Consideration of the findings presented here in future catalyst designs may lead to more-efficient catalysts.

  13. Electron tomography of negatively stained complex viruses: application in their diagnosis

    PubMed Central

    Mast, Jan; Demeestere, Lien

    2009-01-01

    Background Electron tomographic analysis can be combined with the simple and rapid negative staining technique used in electron microscopy based virus diagnosis. Methods Standard negative staining of representative examples of parapoxviruses and paramyxoviruses was combined with electron tomographic analysis. Results Digital sectioning of reconstructions of these viruses at a selected height demonstrated the viral ultrastructure in detail, including the characteristic diagnostic features like the surface threads on C-particles of a parapoxvirus and individual glycoproteins and the internal nucleoprotein strand of Newcastle disease virus. For both viruses, deformation and flattening were observed. Conclusion The combination of negative staining of complex viruses with electron tomographic analysis, allows visualizing and measuring artifacts typical for negative staining. This approach allows sharp visualisation of structures in a subnanometer-thick plane, avoiding blurring due to superposition which is inherent to TEM. In selected examples, such analyses can improve diagnosis of viral agents. PMID:19208223

  14. Electronic structures and magnetic/optical properties of metal phthalocyanine complexes

    SciTech Connect

    Baba, Shintaro; Suzuki, Atsushi Oku, Takeo

    2016-02-01

    Electronic structures and magnetic / optical properties of metal phthalocyanine complexes were studied by quantum calculations using density functional theory. Effects of central metal and expansion of π orbital on aromatic ring as conjugation system on the electronic structures, magnetic, optical properties and vibration modes of infrared and Raman spectra of metal phthalocyanines were investigated. Electron and charge density distribution and energy levels near frontier orbital and excited states were influenced by the deformed structures varied with central metal and charge. The magnetic parameters of chemical shifts in {sup 13}C-nuclear magnetic resonance ({sup 13}C-NMR), principle g-tensor, A-tensor, V-tensor of electric field gradient and asymmetry parameters derived from the deformed structures with magnetic interaction of nuclear quadruple interaction based on electron and charge density distribution with a bias of charge near ligand under crystal field.

  15. Resource allocation for reliability of a complex system with aging components

    SciTech Connect

    Anderson-cook, Christine M; Graves, Todd L; Hamada, Michael S

    2008-01-01

    To assess the reliability of a complex system, many different types of data may be available. Full-system tests are the most direct measure of reliability, but may be prohibitively expensive or difficult to obtain. Other less direct measures, such as component or section level tests, may be cheaper to obtain and more readily available. Using a single Bayesian analysis, multiple sources of data can be combined to give component and system reliability estimates. Resource allocation looks to develop methods to predict which new data would most improve the precision of the estimate of system reliability, in order to maximally improve understanding. In this paper, we consider a relatively simple system with different types of data from the components and system. We present a methodology for assessing the relative improvement in system reliability estimation for additional data from the various types. Various metrics for comparing improvement and a response surface approach to modeling the relationship between improvement and the additional data are presented.

  16. The systems genetics resource: a web application to mine global data for complex disease traits.

    PubMed

    van Nas, Atila; Pan, Calvin; Ingram-Drake, Leslie A; Ghazalpour, Anatole; Drake, Thomas A; Sobel, Eric M; Papp, Jeanette C; Lusis, Aldons J

    2013-01-01

    The Systems Genetics Resource (SGR) (http://systems.genetics.ucla.edu) is a new open-access web application and database that contains genotypes and clinical and intermediate phenotypes from both human and mouse studies. The mouse data include studies using crosses between specific inbred strains and studies using the Hybrid Mouse Diversity Panel. SGR is designed to assist researchers studying genes and pathways contributing to complex disease traits, including obesity, diabetes, atherosclerosis, heart failure, osteoporosis, and lipoprotein metabolism. Over the next few years, we hope to add data relevant to deafness, addiction, hepatic steatosis, toxin responses, and vascular injury. The intermediate phenotypes include expression array data for a variety of tissues and cultured cells, metabolite levels, and protein levels. Pre-computed tables of genetic loci controlling intermediate and clinical phenotypes, as well as phenotype correlations, are accessed via a user-friendly web interface. The web site includes detailed protocols for all of the studies. Data from published studies are freely available; unpublished studies have restricted access during their embargo period.

  17. PGSB/MIPS Plant Genome Information Resources and Concepts for the Analysis of Complex Grass Genomes.

    PubMed

    Spannagl, Manuel; Bader, Kai; Pfeifer, Matthias; Nussbaumer, Thomas; Mayer, Klaus F X

    2016-01-01

    PGSB (Plant Genome and Systems Biology; formerly MIPS-Munich Institute for Protein Sequences) has been involved in developing, implementing and maintaining plant genome databases for more than a decade. Genome databases and analysis resources have focused on individual genomes and aim to provide flexible and maintainable datasets for model plant genomes as a backbone against which experimental data, e.g., from high-throughput functional genomics, can be organized and analyzed. In addition, genomes from both model and crop plants form a scaffold for comparative genomics, assisted by specialized tools such as the CrowsNest viewer to explore conserved gene order (synteny) between related species on macro- and micro-levels.The genomes of many economically important Triticeae plants such as wheat, barley, and rye present a great challenge for sequence assembly and bioinformatic analysis due to their enormous complexity and large genome size. Novel concepts and strategies have been developed to deal with these difficulties and have been applied to the genomes of wheat, barley, rye, and other cereals. This includes the GenomeZipper concept, reference-guided exome assembly, and "chromosome genomics" based on flow cytometry sorted chromosomes.

  18. Electronic Resource Sharing in Community Colleges: A Snapshot of Florida, Wisconsin, Texas, and Louisiana.

    ERIC Educational Resources Information Center

    Mahoney, Brian D.

    2000-01-01

    States that several states are establishing networks for resource sharing. Florida offers these resources through the Florida Distance Learning Library Initiative, Wisconsin has BadgerLink and WISCAT, TexShare provides library resource sharing in Texas, and Louisiana has LOUIS and LLN. These are some of the states successfully demonstrating…

  19. A theoretical study on the electronic structures and equilibrium constants evaluation of Deferasirox iron complexes.

    PubMed

    Salehi, Samie; Saljooghi, Amir Shokooh; Izadyar, Mohammad

    2016-10-01

    Elemental iron is essential for cellular growth and homeostasis but it is potentially toxic to the cells and tissues. Excess iron can contribute in tumor initiation and tumor growth. Obviously, in iron overload issues using an iron chelator in order to reduce iron concentration seems to be vital. This study presents the density functional theory calculations of the electronic structure and equilibrium constant for iron-deferasirox (Fe-DFX) complexes in the gas phase, water and DMSO. A comprehensive study was performed to investigate the Deferasirox-iron complexes in chelation therapy. Calculation was performed in CAMB3LYP/6-31G(d,p) to get the optimized structures for iron complexes in high and low spin states. Natural bond orbital and quantum theory of atoms in molecules analyses was carried out with B3LYP/6-311G(d,p) to understand the nature of complex bond character and electronic transition in complexes. Electrostatic potential effects on the complexes were evaluated using the CHelpG calculations. The results indicated that higher affinity for Fe(III) is not strictly a function of bond length but also the degree of Fe-X (X=O,N) covalent bonding. Based on the quantum reactivity parameters which have been investigated here, it is possible reasonable design of the new chelators to improve the chelator abilities.

  20. Mechanistic studies of photoinduced spin crossover and electron transfer in inorganic complexes.

    PubMed

    Zhang, Wenkai; Gaffney, Kelly J

    2015-04-21

    Electronic excited-state phenomena provide a compelling intersection of fundamental and applied research interests in the chemical sciences. This holds true for coordination chemistry, where harnessing the strong optical absorption and photocatalytic activity of compounds depends on our ability to control fundamental physical and chemical phenomena associated with the nonadiabatic dynamics of electronic excited states. The central events of excited-state chemistry can critically influence the dynamics of electronic excited states, including internal conversion (transitions between distinct electronic states) and intersystem crossing (transitions between electronic states with different spin multiplicities), events governed by nonadiabatic interactions between electronic states in close proximity to conical intersections, as well as solvation and electron transfer. The diversity of electronic and nuclear dynamics also makes the robust interpretation of experimental measurements challenging. Developments in theory, simulation, and experiment can all help address the interpretation and understanding of chemical dynamics in organometallic and coordination chemistry. Synthesis presents the opportunity to chemically engineer the strength and symmetry of the metal-ligand interactions. This chemical control can be exploited to understand the influence of electronic ground state properties on electronic excited-state dynamics. New time-resolved experimental methods and the insightful exploitation of established methods have an important role in understanding, and ideally controlling, the photophysics and photochemistry of transition metal complexes. Techniques that can disentangle the coupled motion of electrons and nuclear dynamics warrant emphasis. We present a review of electron localization dynamics in charge transfer excited states and the dynamics of photoinitiated spin crossover dynamics. Both electron localization and spin crossover have been investigated by

  1. Proton transfer in phenol-amine complexes: phenol electronic effects on free energy profile in solution.

    PubMed

    Aono, Shinji; Kato, Shigeki

    2010-12-01

    Free energy profiles for the proton transfer reactions in hydrogen-bonded complex of phenol with trimethylamine in methyl chloride solvent are studied with the reference interaction site model self-consistent field method. The reactions in both the electronic ground and excited states are considered. The second-order Møller-Plesset perturbation (MP) theory or the second-order multireference MP theory is used to evaluate the effect of the dynamical electron correlation on the free energy profiles. The free energy surface in the ground state shows a discrepancy with the experimental results for the related hydrogen-bonded complexes. To resolve this discrepancy, the effects of chloro-substitutions in phenol are examined, and its importance in stabilizing the ionic form is discussed. The temperature effect is also studied. In contrast to the ground state, the ππ* excited state of phenol-trimethylamine complex exhibits the proton transfer reaction with a low barrier. The reaction is almost thermoneutral. This is attributed to the reduction of proton affinity of phenol by the ππ* electronic excitation. We further examine the possibility of the electron-proton-coupled transfer in the ππ* state through the surface crossing with the charge transfer type πσ* state.

  2. Density functional theory study on the ionization potentials and electron affinities of thymine-formamide complexes

    NASA Astrophysics Data System (ADS)

    Sun, Haitao; Tang, Ke; Li, Yanmin; Su, Chunfang; Zhou, Zhengyu; Wang, Zhizhong

    The effect of hydrogen bond interactions on ionization potentials (IPs) and electron affinities (EAs) of thymine-formamide complexes (T-F) have been investigated employing the density functional theory B3LYP at 6-311++G(d, p) basis set level. All complexes experience a geometrical change on either electron detachment or attachment, and the change might be facilitated or hindered according to the strength of the hydrogen-bonding interaction involved. The strength of hydrogen bonds presents an opposite changing trend on the two processes. A more important role that H-bonding interaction plays in the process of electron attachment than in the process of electron detachment can be seen by a comparison of the IPs and EAs of complexes with that of isolated thymine. Futhermore, the EAs of isolated thymine are in good agreement with the experimental values (AEA is 0.79 eV, VEA is -0.29 eV [Wetmore et al., Chem Phys Lett 2000, 322, 129]). The calculated total NPA charge distributions reveal that nearly all the negative charges locate on thymine monomer in the anions and even in the cationic states, there are a few negative charges on thymine monomer. An analysis of dissociation energies predicts the processes T-F+→ T++ F and T-F- → T- + F to be the most energetically favorable for T-F+ and T-F-, respectively. Content:text/plain; charset="UTF-8"

  3. Design of Photoactive Ruthenium Complexes to Study Electron Transfer and Proton Pumping in Cytochrome Oxidase

    PubMed Central

    Durham, Bill; Millett, Francis

    2011-01-01

    This review describes the development and application of photoactive ruthenium complexes to study electron transfer and proton pumping reactions in cytochrome c oxidase (CcO). CcO uses four electrons from Cc to reduce O2 to two waters, and pumps four protons across the membrane. The electron transfer reactions in cytochrome oxidase are very rapid, and cannot be resolved by stopped-flow mixing techniques. Methods have been developed to covalently attach a photoactive tris(bipyridine)ruthenium group [Ru(II)] to Cc to form Ru-39-Cc. Photoexcitation of Ru(II) to the excited state Ru(II*), a strong reductant, leads to rapid electron transfer to the ferric heme group in Cc, followed by electron transfer to CuA in CcO with a rate constant of 60,000 s−1. Ruthenium kinetics and mutagenesis studies have been used to define the domain for the interaction between Cc and CcO. New ruthenium dimers have also been developed to rapidly inject electrons into CuA of CcO with yields as high as 60%, allowing measurement of the kinetics of electron transfer and proton release at each step in the oxygen reduction mechanism. PMID:21939635

  4. Design of photoactive ruthenium complexes to study electron transfer and proton pumping in cytochrome oxidase.

    PubMed

    Durham, Bill; Millett, Francis

    2012-04-01

    This review describes the development and application of photoactive ruthenium complexes to study electron transfer and proton pumping reactions in cytochrome c oxidase (CcO). CcO uses four electrons from Cc to reduce O(2) to two waters, and pumps four protons across the membrane. The electron transfer reactions in cytochrome oxidase are very rapid, and cannot be resolved by stopped-flow mixing techniques. Methods have been developed to covalently attach a photoactive tris(bipyridine)ruthenium group [Ru(II)] to Cc to form Ru-39-Cc. Photoexcitation of Ru(II) to the excited state Ru(II*), a strong reductant, leads to rapid electron transfer to the ferric heme group in Cc, followed by electron transfer to Cu(A) in CcO with a rate constant of 60,000s(-1). Ruthenium kinetics and mutagenesis studies have been used to define the domain for the interaction between Cc and CcO. New ruthenium dimers have also been developed to rapidly inject electrons into Cu(A) of CcO with yields as high as 60%, allowing measurement of the kinetics of electron transfer and proton release at each step in the oxygen reduction mechanism.

  5. The mechanism of coupling between electron transfer and proton translocation in respiratory complex I.

    PubMed

    Sazanov, Leonid A

    2014-08-01

    NADH-ubiquinone oxidoreductase (complex I) is the first and largest enzyme in the respiratory chain of mitochondria and many bacteria. It couples the transfer of two electrons between NADH and ubiquinone to the translocation of four protons across the membrane. Complex I is an L-shaped assembly formed by the hydrophilic (peripheral) arm, containing all the redox centres performing electron transfer and the membrane arm, containing proton-translocating machinery. Mitochondrial complex I consists of 44 subunits of about 1 MDa in total, whilst the prokaryotic enzyme is simpler and generally consists of 14 conserved "core" subunits. Recently we have determined the first atomic structure of the entire complex I, using the enzyme from Thermus thermophilus (536 kDa, 16 subunits, 9 Fe-S clusters, 64 TM helices). Structure suggests a unique coupling mechanism, with redox energy of electron transfer driving proton translocation via long-range (up to ~200 Å) conformational changes. It resembles a steam engine, with coupling elements (akin to coupling rods) linking parts of this molecular machine.

  6. Multi-Electron Oxidation of Anthracene Derivatives by Nonheme Manganese(IV)-Oxo Complexes.

    PubMed

    Sharma, Namita; Jung, Jieun; Lee, Yong-Min; Seo, Mi Sook; Nam, Wonwoo; Fukuzumi, Shunichi

    2017-03-27

    Six-electron oxidation of anthracene to anthraquinone by a nonheme Mn(IV)-oxo complex, [(Bn-TPEN)MnIV(O)]2+, proceeds via the rate-determining electron transfer from anthracene to [(Bn-TPEN)MnIV(O)]2+, followed by subsequent fast oxidation reactions to give anthraquinone. The reduced Mn(II) complex ([(Bn-TPEN)MnII]2+) is oxidized by [(Bn-TPEN)MnIV(O)]2+ rapidly to produce the μ-oxo dimer ([(Bn-TPEN)MnIII-O-MnIII(Bn-TPEN)]4+). The oxygen atoms of the anthraquinone product were found to derive from the manganese-oxo species by the 18O labelling experiments. In the presence of Sc3+ ion, formation of anthracene radical cation was directly detected in electron transfer from anthracene to a Sc3+ ion-bound MnIV(O) com-plex, [(Bn-TPEN)MnIV(O)-(Sc(OTf)3)2]2+, followed by subsequent further oxidation to yield anthraquinone. When anthracene was replaced by 9,10-dimethylanthracene, elec-tron transfer from 9,10-dimethylanthracene to [(Bn-TPEN)MnIV(O)-(Sc(OTf)3)2]2+ occurred rapidly to produce stable 9,10-dimethylanthracene radical cation. The driving force dependence of the rate constants of electron transfer from anthracene derivatives to [(Bn-TPEN)MnIV(O)]2+ and [(Bn-TPEN)MnIV(O)-(Sc(OTf)3)2]2+ was well evaluated in light of the Marcus theory of electron transfer.

  7. Novel open-source electronic medical records system for palliative care in low-resource settings

    PubMed Central

    2013-01-01

    Background The need for palliative care in sub-Saharan Africa is staggering: this region shoulders over 67% of the global burden of HIV/AIDS and cancer. However, provisions for these essential services remain limited and poorly integrated with national health systems in most nations. Moreover, the evidence base for palliative care in the region remains scarce. This study chronicles the development and evaluation of DataPall, an open-source electronic medical records system that can be used to track patients, manage data, and generate reports for palliative care providers in these settings. DataPall was developed using design criteria encompassing both functional and technical objectives articulated by hospital leaders and palliative care staff at a leading palliative care center in Malawi. The database can be used with computers that run Windows XP SP 2 or newer, and does not require an internet connection for use. Subsequent to its development and implementation in two hospitals, DataPall was tested among both trained and untrained hospital staff populations on the basis of its usability with comparison to existing paper records systems as well as on the speed at which users could perform basic database functions. Additionally, all participants evaluated this program on a standard system usability scale. Results In a study of health professionals in a Malawian hospital, DataPall enabled palliative care providers to find patients’ appointments, on average, in less than half the time required to locate the same record in current paper records. Moreover, participants generated customizable reports documenting patient records and comprehensive reports on providers’ activities with little training necessary. Participants affirmed this ease of use on the system usability scale. Conclusions DataPall is a simple, effective electronic medical records system that can assist in developing an evidence base of clinical data for palliative care in low resource settings. The

  8. Focusing on Patient Safety: the Challenge of Securely Sharing Electronic Medical Records in Complex Care Continuums.

    PubMed

    Key, Diana; Ferneini, Elie M

    2015-09-01

    The Patient Protection and Affordable Care Act's (PPACA) regulated approach to inclusive provision of care will increase the challenge health care administrators face ensuring secure communication and secure sharing of electronic medical records between divisions and care subcontractors. This analysis includes a summary overview of the PPACA; the Health Care and Education Reconciliation Act (HCERA) of 2010; and required Essential Health Benefits (EHB). The analysis integrates an overview of how secure communication and secure sharing of electronic medical records will be essential to clinical outcomes across complex care continuums; as well as the actionable strategies health care leadership can employ to overcome associated IT security challenges.

  9. Interface electronic complexes and Landau damping of magnons in ultrathin magnets.

    PubMed

    Buczek, Paweł; Ernst, Arthur; Sandratskii, Leonid M

    2011-04-15

    The damping of magnons in ultrathin metallic magnets is studied from first-principles. We contrast Fe/Cu(100) and Fe/W(110) systems for which the influence of the substrate on the magnon life time differs strongly. We introduce the concept of Landau map in momentum space to assess the role of different electronic states in the attenuation. The formation of electronic complexes localized at the film-substrate interface leads to hot spots in the Landau maps and enhances the damping. This finding allows tuning the attenuation of high-frequency magnetization dynamics in nanostructures.

  10. Quantum-chemical investigation of the structure and electronic absorption spectra of electroluminescent zinc complexes

    NASA Astrophysics Data System (ADS)

    Minaev, B. F.; Baryshnikov, G. V.; Korop, A. A.; Minaeva, V. A.; Kaplunov, M. G.

    2013-01-01

    Using the quantum chemical methods of the density functional theory and of the electron density topological analysis, we have studied the structure of two recently synthesized electroluminescent zinc complexes, one with aminoquinoline ligands and the other with a Schiff base (N,O-donor). The energies and intensities of vertical excitations for the molecules under study have been calculated in terms of the PM3 semiempirical approximation taking into account the configurational interaction between singly excited singlet excited states. Good agreement between calculation results and experimental data on the electron density topological characteristics and on the visible and UV absorption spectra has been obtained.

  11. Systematically Assessing the Situational Relevance of Electronic Knowledge Resources: A Mixed Methods Study

    PubMed Central

    Pluye, Pierre; Grad, Roland M.; Mysore, Naveen; Knaapen, Loes; Johnson-Lafleur, Janique; Dawes, Martin

    2007-01-01

    Electronic Knowledge Resources (EKRs) are increasingly used by physicians, but their situational relevance has not been systematically examined. Objective Systematically scrutinize the situational relevance of EKR-derived information items in and outside clinical settings. Background Physicians use EKRs to accomplish four cognitive objectives (C1-4), and three organizational objectives (O1-3): (C1) Answer questions/solve problems/support decision-making in a clinical context; (C2) fulfill educational-research objectives; (C3) search for personal interest or curiosity; (C4) overcome limits of human memory; (O1) share information with patients, families, or caregivers; (O2) exchange information with other health professionals; (O3) plan-manage-monitor tasks with other health professionals. Methods Longitudinal mixed methods multiple case study: Cases were 17 residents’ critical searches for information, using a commercial EKR, during a 2-month block of family practice. Usage data were automatically recorded. Each “opened” item of information was linked to an impact assessment questionnaire, and 1,981 evaluations of items were documented. Interviews with residents were guided by log files, which tracked use and impact of EKR-derived information items. Thematic analysis identified 156 critical searches linked to 877 information items. For each case, qualitative data were assigned to one of the seven proposed objectives. Results Residents achieved their search objectives in 85.9% of cases (situational relevance). Additional sources of information were sought in 52.6% of cases. Results support the seven proposed objectives, levels of comparative relevance (less, equally, more), and levels of stimulation of learning and knowledge (individual, organizational). Conclusion Our method of systematic assessment may contribute to user-based evaluation of EKRs. PMID:17600105

  12. Cultural Resource Investigation for the Materials and Fuels Complex Wastewater System Upgrade at the Idaho National Laboratory

    SciTech Connect

    Brenda R. Pace; Julie B raun Williams; Hollie Gilbert; Dino Lowrey; Julie Brizzee

    2010-05-01

    The Materials and Fuels Complex (MFC) located in Bingham County at the Idaho National Laboratory (INL) in southeastern Idaho is considering several alternatives to upgrade wastewater systems to meet future needs at the facility. In April and May of 2010, the INL Cultural Resource Management Office conducted archival searches, archaeological field surveys, and coordination with the Shoshone-Bannock Tribes to identify cultural resources that may be adversely affected by the proposed construction and to provide recommendations to protect any resources listed or eligible for listing on the National Register of Historic Places. These investigations showed that one National Register-eligible archaeological site is located on the boundary of the area of potential effects for the wastewater upgrade. This report outlines protective measures to help ensure that this resource is not adversely affected by construction.

  13. Energetics, molecular electronic structure, and spectroscopy of forming Group IIA dihalide complexes

    NASA Astrophysics Data System (ADS)

    Devore, T. C.; Gole, J. L.

    1999-02-01

    Multiple-collision relaxed (helium) chemiluminescence and laser-induced fluorescent spectroscopy have been used to demonstrate the highly efficient collisional stabilization of electronically excited Group IIA dihalide collision complexes formed in M (Ca,Sr)+X 2 (XY) (Cl 2, Br 2, ICl, IBr, I 2) reactive encounters. The first discrete emission spectra for the CaCl 2, CaBr 2, SrCl 2, SrBr 2, and SrICl dihalides are observed and evaluated; however, the low-pressure `continuous' chemiluminescent emission observed for forming barium dihalide (BaX 2) complexes is quenched under these experimental conditions. The reactions of the Group IIA metals with molecular fluorine do not readily produce the corresponding dihalide. While the lowest-lying observed dihalide visible transition is, as predicted, found to result in an extended progression in a dihalide complex bending mode (SrCl 2), the observed progression suggests the presence of a residual halogen (Cl-Cl) bond. Two higher-lying transitions are dominated by a vibrational mode structure corresponding to progressions in the symmetric stretching mode or, for nominally forbidden electronic transitions, odd quanta of the asymmetric stretching mode. Some evidence for sequence structure associated with the dihalide bending mode is also obtained. These observations are consistent with complex formation as it is coupled with a modified valence electron structure (correlation diagram) associated with the highly ionic nature of the dihalides. The bonding in the Group IIA dihalides (and their complexes), whose atomization energies are more than twice the metal monohalide bond energy, strongly influences the evaluation of energetics and the determination of monohalide bond energies from chemiluminescent processes. Discrepancies between those bond strengths determined by mass spectrometry and chemiluminescence are discussed with a focus on energy partitioning in dihalide complex formation and its influence on chemical vapor

  14. Choice of data extraction tools for systematic reviews depends on resources and review complexity.

    PubMed

    Elamin, Mohamed B; Flynn, David N; Bassler, Dirk; Briel, Matthias; Alonso-Coello, Pablo; Karanicolas, Paul Jack; Guyatt, Gordon H; Malaga, German; Furukawa, Toshiaki A; Kunz, Regina; Schünemann, Holger; Murad, Mohammad Hassan; Barbui, Corrado; Cipriani, Andrea; Montori, Victor M

    2009-05-01

    To assist investigators planning, coordinating, and conducting systematic reviews in the selection of data-extraction tools for conducting systematic reviews. We constructed an initial table listing available data-collection tools and reflecting our experience with these tools and their performance. An international group of experts iteratively reviewed the table and reflected on the performance of the tools until no new insights and consensus resulted. Several tools are available to manage data in systematic reviews, including paper and pencil, spreadsheets, web-based surveys, electronic databases, and web-based specialized software. Each tool offers benefits and drawbacks: specialized web-based software is well suited in most ways, but is associated with higher setup costs. Other approaches vary in their setup costs and difficulty, training requirements, portability and accessibility, versatility, progress tracking, and the ability to manage, present, store, and retrieve data. Available funding, number and location of reviewers, data needs, and the complexity of the project should govern the selection of a data-extraction tool when conducting systematic reviews.

  15. Interfacial Electron Transfer in TiO2 Surfaces Sensitized with Ru(II)-Polypyridine Complexes

    NASA Astrophysics Data System (ADS)

    Jakubikova, Elena; Snoeberger, Robert C., III; Batista, Victor S.; Martin, Richard L.; Batista, Enrique R.

    2009-07-01

    Studies of interfacial electron transfer (IET) in TiO2 surfaces functionalized with (1) pyridine-4-phosphonic acid, (2) [Ru(tpy)(tpy(PO3H2))]2+, and (3) [Ru(tpy)(bpy)(H2O)-Ru(tpy)(tpy(PO3H2))]4+ (tpy = 2,2':6,2''-terpyridine; bpy = 2,2'-bipyridine) are reported. We characterize the electronic excitations, electron injection time scales, and interfacial electron transfer (IET) mechanisms through phosphonate anchoring groups. These are promising alternatives to the classic carboxylates of conventional dye-sensitized solar cells since they bind more strongly to TiO2 surfaces and form stable covalent bonds that are unaffected by humidity. Density functional theory calculations and quantum dynamics simulations of IET indicate that electron injection in 1-TiO2 can be up to 1 order of magnitude faster when 1 is attached to TiO2 in a bidentate mode (τ ˜ 60 fs) than when attached in a monodentate motif (τ ˜ 460 fs). The IET time scale also depends strongly on the properties of the sensitizer as well as on the nature of the electronic excitation initially localized in the adsorbate molecule. We show that IET triggered by the visible light excitation of 2-TiO2 takes 1-10 ps when 2 is attached in a bidentate mode, a time comparable to the lifetime of the excited electronic state. IET due to visible-light photoexcitation of 3-TiO2 is slower, since the resulting electronic excitation remains localized in the tpy-tpy bridge that is weakly coupled to the electronic states of the conduction band of TiO2. These results are particularly valuable to elucidate the possible origin of IET efficiency drops during photoconversion in solar cells based on Ru(II)-polypyridine complexes covalently attached to TiO2 thin films with phosphonate linkers.

  16. Interfacial electron transfer in TiO(2) surfaces sensitized with Ru(II)-polypyridine complexes.

    PubMed

    Jakubikova, Elena; Snoeberger, Robert C; Batista, Victor S; Martin, Richard L; Batista, Enrique R

    2009-11-12

    Studies of interfacial electron transfer (IET) in TiO(2) surfaces functionalized with (1) pyridine-4-phosphonic acid, (2) [Ru(tpy)(tpy(PO(3)H(2)))](2+), and (3) [Ru(tpy)(bpy)(H(2)O)-Ru(tpy)(tpy(PO(3)H(2)))](4+) (tpy = 2,2':6,2''-terpyridine; bpy = 2,2'-bipyridine) are reported. We characterize the electronic excitations, electron injection time scales, and interfacial electron transfer (IET) mechanisms through phosphonate anchoring groups. These are promising alternatives to the classic carboxylates of conventional dye-sensitized solar cells since they bind more strongly to TiO(2) surfaces and form stable covalent bonds that are unaffected by humidity. Density functional theory calculations and quantum dynamics simulations of IET indicate that electron injection in 1-TiO(2) can be up to 1 order of magnitude faster when 1 is attached to TiO(2) in a bidentate mode (tau approximately 60 fs) than when attached in a monodentate motif (tau approximately 460 fs). The IET time scale also depends strongly on the properties of the sensitizer as well as on the nature of the electronic excitation initially localized in the adsorbate molecule. We show that IET triggered by the visible light excitation of 2-TiO(2) takes 1-10 ps when 2 is attached in a bidentate mode, a time comparable to the lifetime of the excited electronic state. IET due to visible-light photoexcitation of 3-TiO(2) is slower, since the resulting electronic excitation remains localized in the tpy-tpy bridge that is weakly coupled to the electronic states of the conduction band of TiO(2). These results are particularly valuable to elucidate the possible origin of IET efficiency drops during photoconversion in solar cells based on Ru(II)-polypyridine complexes covalently attached to TiO(2) thin films with phosphonate linkers.

  17. Electronic Spectra of TRIS(2,2'-BIPYRIDINE)-METAL Complex Ions in Gas Phase

    NASA Astrophysics Data System (ADS)

    Xu, Shuang; Smith, James E. T.; Weber, J. Mathias

    2016-06-01

    Tris(bpy)-metal complexes (bpy = 2,2'-bipyridine) and their derivatives are important systems in metal-organic chemistry. While tris(bpy)-ruthenium, Ru(bpy)32+, has been extensively studied, less attention has been paid to analogous complexes involving first row transition metals. Here we report the electronic spectra of a series of dicationic tris(bpy) chelates with different transition metals, measured by photodisscociation spectroscopy of cryogenically prepared ions. We focus our attention on the π-π* transitions in the UV region of the spectrum.

  18. Effective Knowledge Development in Secondary Schools Educational Level in Contemporary Information Age: Assessment of Availability of Electronic Information Resources in Nigerian School Libraries

    ERIC Educational Resources Information Center

    Bello, Stephen Adeyemi; Ojo, Funmilayo Roseline; Ocheje, Charles Bala

    2015-01-01

    Relevant electronic information resources in contemporary information age are necessity to buttress teaching and learning for effective knowledge development in educational institutions. The purpose of the study is to know the state of availability of electronic information resources in government owned secondary school libraries in Ijumu Local…

  19. Complex Households and the Distribution of Multiple Resources in Later Life: Findings from A National Survey

    PubMed Central

    Kim, Juyeon; Link, Arts; Waite, Linda

    2016-01-01

    The availability of social and financial resources has profound implications for health and well-being in later life. Older adults often share resources with others who live with them, sometimes in households including relatives or friends. We examine differences in social support, social connections, money, and the household environment across types of living arrangements, develop hypotheses from two theoretical perspectives, one focusing on obligations toward kin, and one focused on social exchange within households, and test them using data from the National Social Life, Health, and Aging Project. We find that availability of resources is not consistently associated with the presence of grandchildren and other young relatives, but often differs with presence of other adults. These findings suggest that a single type of resource tells us little about the distribution of the resources of older adults, and call on us to examine multiple resources simultaneously. PMID:25904682

  20. Impact of an Evidence-Based Medicine Curriculum on Resident Use of Electronic Resources: A Randomized Controlled Study

    PubMed Central

    Willett, Laura R.; Murphy, David J.; O’Rourke, Kerry; Sharma, Ranita; Shea, Judy A.

    2008-01-01

    Background Evidence-based medicine (EBM) is widely taught in residency, but evidence for effectiveness of EBM teaching on changing residents’ behavior is limited. Objective To investigate the impact of an EBM curriculum on residents’ use of evidence-based resources in a simulated clinical experience. Design/Participants Fifty medicine residents randomized to an EBM teaching or control group. Measurements A validated test of EBM knowledge (Fresno test) was administered before and after intervention. Post intervention, residents twice completed a Web-based, multiple-choice instrument (15 items) comprised of clinical vignettes, first without then with access to electronic resources. Use of electronic resources was tracked using ProxyPlus software. Within group pre–post differences and between group post-test differences were examined. Results There was more improvement in EBM knowledge (100-point scale) for the intervention group compared to the control group (mean score increase 22 vs. 12,  = 0.012). In the simulated clinical experience, the most commonly accessed resources were Ovid (71% of residents accessed) and InfoPOEMs (62%) for the EBM group and UptoDate (67%) and MDConsult (58%) for the control group. Residents in the EBM group were more likely to use evidence-based resources than the control group. Performance on clinical vignettes was similar between the groups both at baseline ( = 0.19) and with access to information resources ( = 0.89). Conclusions EBM teaching improved EBM knowledge and increased use of evidence-based resources by residents, but did not improve performance on Web-based clinical vignettes. Future studies will need to examine impact of EBM teaching on clinical outcomes. PMID:18769979

  1. Solar resource assessment in complex orography: a comparison of available datasets for the Trentino region

    NASA Astrophysics Data System (ADS)

    Laiti, Lavinia; Giovannini, Lorenzo; Zardi, Dino

    2015-04-01

    The accurate assessment of the solar radiation available at the Earth's surface is essential for a wide range of energy-related applications, such as the design of solar power plants, water heating systems and energy-efficient buildings, as well as in the fields of climatology, hydrology, ecology and agriculture. The characterization of solar radiation is particularly challenging in complex-orography areas, where topographic shadowing and altitude effects, together with local weather phenomena, greatly increase the spatial and temporal variability of such variable. At present, approaches ranging from surface measurements interpolation to orographic down-scaling of satellite data, to numerical model simulations are adopted for mapping solar radiation. In this contribution a high-resolution (200 m) solar atlas for the Trentino region (Italy) is presented, which was recently developed on the basis of hourly observations of global radiation collected from the local radiometric stations during the period 2004-2012. Monthly and annual climatological irradiation maps were obtained by the combined use of a GIS-based clear-sky model (r.sun module of GRASS GIS) and geostatistical interpolation techniques (kriging). Moreover, satellite radiation data derived by the MeteoSwiss HelioMont algorithm (2 km resolution) were used for missing-data reconstruction and for the final mapping, thus integrating ground-based and remote-sensing information. The results are compared with existing solar resource datasets, such as the PVGIS dataset, produced by the Joint Research Center Institute for Energy and Transport, and the HelioMont dataset, in order to evaluate the accuracy of the different datasets available for the region of interest.

  2. Solar-thermal complex sample processing for nucleic acid based diagnostics in limited resource settings.

    PubMed

    Gumus, Abdurrahman; Ahsan, Syed; Dogan, Belgin; Jiang, Li; Snodgrass, Ryan; Gardner, Andrea; Lu, Zhengda; Simpson, Kenneth; Erickson, David

    2016-05-01

    The use of point-of-care (POC) devices in limited resource settings where access to commonly used infrastructure, such as water and electricity, can be restricted represents simultaneously one of the best application fits for POC systems as well as one of the most challenging places to deploy them. Of the many challenges involved in these systems, the preparation and processing of complex samples like stool, vomit, and biopsies are particularly difficult due to the high number and varied nature of mechanical and chemical interferents present in the sample. Previously we have demonstrated the ability to use solar-thermal energy to perform PCR based nucleic acid amplifications. In this work demonstrate how the technique, using similar infrastructure, can also be used to perform solar-thermal based sample processing system for extracting and isolating Vibrio Cholerae nucleic acids from fecal samples. The use of opto-thermal energy enables the use of sunlight to drive thermal lysing reactions in large volumes without the need for external electrical power. Using the system demonstrate the ability to reach a 95°C threshold in less than 5 minutes and maintain a stable sample temperature of +/- 2°C following the ramp up. The system is demonstrated to provide linear results between 10(4) and 10(8) CFU/mL when the released nucleic acids were quantified via traditional means. Additionally, we couple the sample processing unit with our previously demonstrated solar-thermal PCR and tablet based detection system to demonstrate very low power sample-in-answer-out detection.

  3. Solar-thermal complex sample processing for nucleic acid based diagnostics in limited resource settings

    PubMed Central

    Gumus, Abdurrahman; Ahsan, Syed; Dogan, Belgin; Jiang, Li; Snodgrass, Ryan; Gardner, Andrea; Lu, Zhengda; Simpson, Kenneth; Erickson, David

    2016-01-01

    The use of point-of-care (POC) devices in limited resource settings where access to commonly used infrastructure, such as water and electricity, can be restricted represents simultaneously one of the best application fits for POC systems as well as one of the most challenging places to deploy them. Of the many challenges involved in these systems, the preparation and processing of complex samples like stool, vomit, and biopsies are particularly difficult due to the high number and varied nature of mechanical and chemical interferents present in the sample. Previously we have demonstrated the ability to use solar-thermal energy to perform PCR based nucleic acid amplifications. In this work demonstrate how the technique, using similar infrastructure, can also be used to perform solar-thermal based sample processing system for extracting and isolating Vibrio Cholerae nucleic acids from fecal samples. The use of opto-thermal energy enables the use of sunlight to drive thermal lysing reactions in large volumes without the need for external electrical power. Using the system demonstrate the ability to reach a 95°C threshold in less than 5 minutes and maintain a stable sample temperature of +/− 2°C following the ramp up. The system is demonstrated to provide linear results between 104 and 108 CFU/mL when the released nucleic acids were quantified via traditional means. Additionally, we couple the sample processing unit with our previously demonstrated solar-thermal PCR and tablet based detection system to demonstrate very low power sample-in-answer-out detection. PMID:27231636

  4. Coherent operation of detector systems and their readout electronics in a complex experiment control environment

    NASA Astrophysics Data System (ADS)

    Koestner, Stefan

    2009-09-01

    With the increasing size and degree of complexity of today's experiments in high energy physics the required amount of work and complexity to integrate a complete subdetector into an experiment control system is often underestimated. We report here on the layered software structure and protocols used by the LHCb experiment to control its detectors and readout boards. The experiment control system of LHCb is based on the commercial SCADA system PVSS II. Readout boards which are outside the radiation area are accessed via embedded credit card sized PCs which are connected to a large local area network. The SPECS protocol is used for control of the front end electronics. Finite state machines are introduced to facilitate the control of a large number of electronic devices and to model the whole experiment at the level of an expert system.

  5. Heptachlor induced mitochondria-mediated cell death via impairing electron transport chain complex III

    SciTech Connect

    Hong, Seokheon; Kim, Joo Yeon; Hwang, Joohyun; Shin, Ki Soon; Kang, Shin Jung

    2013-08-09

    Highlights: •Heptachlor inhibited mitochondrial electron transport chain complex III activity. •Heptachlor promoted generation of reactive oxygen species. •Heptachlor induced Bax activation. •Heptachlor induced mitochondria-mediated and caspase-dependent apoptosis. -- Abstract: Environmental toxins like pesticides have been implicated in the pathogenesis of Parkinson’s disease (PD). Epidemiological studies suggested that exposures to organochlorine pesticides have an association with an increased PD risk. In the present study, we examined the mechanism of toxicity induced by an organochlorine pesticide heptachlor. In a human dopaminergic neuroblastoma SH-SY5Y cells, heptachlor induced both morphological and functional damages in mitochondria. Interestingly, the compound inhibited mitochondrial electron transport chain complex III activity. Rapid generation of reactive oxygen species and the activation of Bax were then detected. Subsequently, mitochondria-mediated, caspase-dependent apoptosis followed. Our results raise a possibility that an organochlorine pesticide heptachlor can act as a neurotoxicant associated with PD.

  6. Analyzing the Heterogeneity and Complexity of Electronic Health Record Oriented Phenotyping Algorithms

    PubMed Central

    Conway, Mike; Berg, Richard L.; Carrell, David; Denny, Joshua C.; Kho, Abel N.; Kullo, Iftikhar J.; Linneman, James G.; Pacheco, Jennifer A.; Peissig, Peggy; Rasmussen, Luke; Weston, Noah; Chute, Christopher G.; Pathak, Jyotishman

    2011-01-01

    The need for formal representations of eligibility criteria for clinical trials – and for phenotyping more generally – has been recognized for some time. Indeed, the availability of a formal computable representation that adequately reflects the types of data and logic evidenced in trial designs is a prerequisite for the automatic identification of study-eligible patients from Electronic Health Records. As part of the wider process of representation development, this paper reports on an analysis of fourteen Electronic Health Record oriented phenotyping algorithms (developed as part of the eMERGE project) in terms of their constituent data elements, types of logic used and temporal characteristics. We discovered that the majority of eMERGE algorithms analyzed include complex, nested boolean logic and negation, with several dependent on cardinality constraints and complex temporal logic. Insights gained from the study will be used to augment the CDISC Protocol Representation Model. PMID:22195079

  7. Pure electronic metal-insulator transition at the interface of complex oxides

    PubMed Central

    Meyers, D.; Liu, Jian; Freeland, J. W.; Middey, S.; Kareev, M.; Kwon, Jihwan; Zuo, J. M.; Chuang, Yi-De; Kim, J. W.; Ryan, P. J.; Chakhalian, J.

    2016-01-01

    In complex materials observed electronic phases and transitions between them often involve coupling between many degrees of freedom whose entanglement convolutes understanding of the instigating mechanism. Metal-insulator transitions are one such problem where coupling to the structural, orbital, charge, and magnetic order parameters frequently obscures the underlying physics. Here, we demonstrate a way to unravel this conundrum by heterostructuring a prototypical multi-ordered complex oxide NdNiO3 in ultra thin geometry, which preserves the metal-to-insulator transition and bulk-like magnetic order parameter, but entirely suppresses the symmetry lowering and long-range charge order parameter. These findings illustrate the utility of heterointerfaces as a powerful method for removing competing order parameters to gain greater insight into the nature of the transition, here revealing that the magnetic order generates the transition independently, leading to an exceptionally rare purely electronic metal-insulator transition with no symmetry change. PMID:27324948

  8. Pure electronic metal-insulator transition at the interface of complex oxides

    SciTech Connect

    Meyers, D.; Liu, Jian; Freeland, J. W.; Middey, S.; Kareev, M.; Kwon, Jihwan; Zuo, J. M.; Chuang, Yi-De; Kim, J. W.; Ryan, P. J.; Chakhalian, J.

    2016-06-21

    We observed complex materials in electronic phases and transitions between them often involve coupling between many degrees of freedom whose entanglement convolutes understanding of the instigating mechanism. Metal-insulator transitions are one such problem where coupling to the structural, orbital, charge, and magnetic order parameters frequently obscures the underlying physics. We demonstrate a way to unravel this conundrum by heterostructuring a prototypical multi-ordered complex oxide NdNiO3 in ultra thin geometry, which preserves the metal-to-insulator transition and bulk-like magnetic order parameter, but entirely suppresses the symmetry lowering and long-range charge order parameter. Furthermore, these findings illustrate the utility of heterointerfaces as a powerful method for removing competing order parameters to gain greater insight into the nature of the transition, here revealing that the magnetic order generates the transition independently, leading to an exceptionally rare purely electronic metal-insulator transition with no symmetry change.

  9. Complex absorbing potentials in the framework of electron propagator theory. II. Application to temporary anions

    NASA Astrophysics Data System (ADS)

    Feuerbacher, Sven; Sommerfeld, Thomas; Santra, Robin; Cederbaum, Lorenz S.

    2003-04-01

    In continuation of Paper I of this work we describe a practical application of the combination of complex absorbing potentials (CAPs) with Green's functions. We use a new approach for calculation of energies and lifetimes of temporary anions, which emerge, e.g., from elastic scattering of electrons from closed-shell targets. This new method is able to treat the continuum and correlation effects simultaneously and reduces the problem to the diagonalization of a number of relatively small, complex symmetric matrices. The efficiency of the proposed method is demonstrated and its dependence on basis set and parameters characterizing the CAP is investigated using the 2Πg resonance state of N2- as an example. We also present the first correlated ab initio calculation of energies and lifetimes of resonances in elastic electron scattering from the organic molecule chlorobenzene. Our results for both examples are in good agreement with existing experimental values and other theoretical calculations. Possible future developments are discussed.

  10. Deactivation pathways of the electronic excitation of ions of lanthanide complexes in polymers with functional groups

    NASA Astrophysics Data System (ADS)

    Sveshnikova, E. B.; Ermolaev, V. L.; Shablya, A. V.; Goĭkhman, M. Ya.; Yakimanskiĭ, A. V.; Podeshvo, I. V.; Kudryavtsev, V. V.

    2007-05-01

    Complexes Eu(TTA)3phen and Eu(MBTA)3phen, as well as complexes Tb(MBTA)3phen and Tb(TTA)3phen, which do not luminesce in solutions, are shown to luminesce in polymer films (TTA is thenoyltrifluoroacetone, MBTA is n-methoxybenzoyltrifluoroacetone, and phen is o-phenanthroline). Luminescence of complexes of Eu and Tb in films of a polymer, poly(methylene-bis-anthranilamide) 1,6-hexamethylenedicarboxylic acid (PAA-5), having a high concentration of functional anthranilate groups, is studied. From the behavior of the luminescence intensity (I lum), the luminescence decay time, and the luminescence spectra of complexes of these lanthanides in polymer films, the following regular features were revealed. (i) During the film preparation at 90°C, Ln complexes are attached to PAA-5 via anthranilate groups. (ii) Irradiation of these films in the range of the absorption band of ligands (TTA or MBTA) leads to deactivation of the electronic excitation of ions according to the diketone detachment mechanism and to further binding of complexes to polymers. In this case, I lum(Eu(III)) decreases because the introduction of anthranilate groups of the polymer into the first coordination sphere of Eu(III) complexes enhances the nonradiative deactivation of these ions, whereas I lum(Tb(III)) increases since the introduction of these groups suppresses the nonradiative deactivation of Tb complexes through triplet states of ligands (TTA and MBTA). (iii) Upon storage of films in the dark (20°C), complexes detach themselves from the polymer and return to their initial structure. In PAA-5 films into which Eu and Tb complexes were simultaneously introduced, the color of the emission from the irradiation spot changes from red to green.

  11. Mechanistic Study on Electronic Excitation Dissociation of the Cellobiose-Na+ Complex

    PubMed Central

    Huang, Yiqun; Pu, Yi; Yu, Xiang; Costello, Catherine E.; Lin, Cheng

    2015-01-01

    The recent development of electron activated dissociation (ExD) techniques has opened the door for high-throughput, detailed glycan structural elucidation. Among them, ExD methods employing higher-energy electrons offer several advantages over low-energy electron capture dissociation (ECD), owing to their applicability towards chromophore-labeled glycans and singly charged ions, and ability to provide more extensive structural information. However, a lack of understanding of these processes has hindered rational optimization of the experimental conditions for more efficient fragmentation, as well as the development of informatics tools for interpretation of the complex glycan ExD spectra. Here, cellobiose-Na+ was used as the model system to investigate the fragmentation behavior of metal-adducted glycans under irradiation of electrons with energy exceeding their ionization potential, and served as the basis on which a novel electronic excitation dissociation (EED) mechanism was proposed. It was found that ionization of the glycan produces a mixture of radical cations and ring-opened distonic ions. These distonic ions then capture a low-energy electron to produce diradicals with trivial singlet-triplet splitting, and subsequently undergo radical-induced dissociation to produce a variety of fragment ions, whose abundances are influenced by the stability of the distonic ions from which they originate. PMID:26432580

  12. On Rate Limitations of Electron Transfer in the Photosynthetic Cytochrome b6f Complex

    PubMed Central

    Hasan, S. Saif; Cramer, William A.

    2012-01-01

    Considering information in the crystal structures of the cytochrome b6f complex relevant to the rate-limiting step in oxygenic photosynthesis (1–5), it is enigmatic that electron transport in the complex is not limited by the large distance, approximately 26 Å, between the iron-sulfur cluster (ISP) and its electron acceptor, cytochrome f. This enigma has been explained for the respiratory bc1 complex by a crystal structure with a greatly shortened cluster-heme c1 distance (6), leading to a concept of ISP dynamics in which the ISP soluble domain undergoes a translation-rotation conformation change and oscillates between positions relatively close to the cyt c1 heme and a membrane-proximal position close to the ubiquinol electron-proton donor. Comparison of cytochrome b6f structures shows a variation in cytochrome f heme position that suggests the possibility of flexibility and motion of the extended cytochrome f structure that could entail a transient decrease in cluster-heme f distance. The dependence of cyt f turnover on lumen viscosity (7) is consistent with a role of ISP - cyt f dynamics in determination of the rate-limiting step under conditions of low light intensity. Under conditions of low light intensity and proton electrochemical gradient present, for example, under a leaf canopy, it is proposed that a rate limitation of electron transport in the b6f complex may also arise from steric constraints in the entry/exit portal for passage of the plastoquinol and -quinone to/from its oxidation site proximal to the iron-sulfur cluster. PMID:22890107

  13. Controlling High-Frequency Collective Electron Dynamics via Single-Particle Complexity

    NASA Astrophysics Data System (ADS)

    Alexeeva, N.; Greenaway, M. T.; Balanov, A. G.; Makarovsky, O.; Patanè, A.; Gaifullin, M. B.; Kusmartsev, F.; Fromhold, T. M.

    2012-07-01

    We demonstrate, through experiment and theory, enhanced high-frequency current oscillations due to magnetically-induced conduction resonances in superlattices. Strong increase in the ac power originates from complex single-electron dynamics, characterized by abrupt resonant transitions between unbound and localized trajectories, which trigger and shape propagating charge domains. Our data demonstrate that external fields can tune the collective behavior of quantum particles by imprinting configurable patterns in the single-particle classical phase space.

  14. Controlling high-frequency collective electron dynamics via single-particle complexity.

    PubMed

    Alexeeva, N; Greenaway, M T; Balanov, A G; Makarovsky, O; Patanè, A; Gaifullin, M B; Kusmartsev, F; Fromhold, T M

    2012-07-13

    We demonstrate, through experiment and theory, enhanced high-frequency current oscillations due to magnetically-induced conduction resonances in superlattices. Strong increase in the ac power originates from complex single-electron dynamics, characterized by abrupt resonant transitions between unbound and localized trajectories, which trigger and shape propagating charge domains. Our data demonstrate that external fields can tune the collective behavior of quantum particles by imprinting configurable patterns in the single-particle classical phase space.

  15. Modeling Electronic-Nuclear Interactions for Excitation Energy Transfer Processes in Light-Harvesting Complexes.

    PubMed

    Lee, Mi Kyung; Coker, David F

    2016-08-18

    An accurate approach for computing intermolecular and intrachromophore contributions to spectral densities to describe the electronic-nuclear interactions relevant for modeling excitation energy transfer processes in light harvesting systems is presented. The approach is based on molecular dynamics (MD) calculations of classical correlation functions of long-range contributions to excitation energy fluctuations and a separate harmonic analysis and single-point gradient quantum calculations for electron-intrachromophore vibrational couplings. A simple model is also presented that enables detailed analysis of the shortcomings of standard MD-based excitation energy fluctuation correlation function approaches. The method introduced here avoids these problems, and its reliability is demonstrated in accurate predictions for bacteriochlorophyll molecules in the Fenna-Matthews-Olson pigment-protein complex, where excellent agreement with experimental spectral densities is found. This efficient approach can provide instantaneous spectral densities for treating the influence of fluctuations in environmental dissipation on fast electronic relaxation.

  16. Exploring the Interaction Natures in Plutonyl (VI) Complexes with Topological Analyses of Electron Density.

    PubMed

    Du, Jiguang; Sun, Xiyuan; Jiang, Gang

    2016-04-11

    The interaction natures between Pu and different ligands in several plutonyl (VI) complexes are investigated by performing topological analyses of electron density. The geometrical structures in both gaseous and aqueous phases are obtained with B3LYP functional, and are generally in agreement with available theoretical and experimental results when combined with all-electron segmented all-electron relativistic contracted (SARC) basis set. The Pu- O y l bond orders show significant linear dependence on bond length and the charge of oxygen atoms in plutonyl moiety. The closed-shell interactions were identified for Pu-Ligand bonds in most complexes with quantum theory of atoms in molecules (QTAIM) analyses. Meanwhile, we found that some Pu-Ligand bonds, like Pu-OH(-), show weak covalent. The interactive nature of Pu-ligand bonds were revealed based on the interaction quantum atom (IQA) energy decomposition approach, and our results indicate that all Pu-Ligand interactions is dominated by the electrostatic attraction interaction as expected. Meanwhile it is also important to note that the quantum mechanical exchange-correlation contributions can not be ignored. By means of the non-covalent interaction (NCI) approach it has been found that some weak and repulsion interactions existed in plutonyl(VI) complexes, which can not be distinguished by QTAIM, can be successfully identified.

  17. Ubisemiquinone is the electron donor for superoxide formation by complex III of heart mitochondria.

    PubMed

    Turrens, J F; Alexandre, A; Lehninger, A L

    1985-03-01

    Much evidence indicates that superoxide is generated from O2 in a cyanide-sensitive reaction involving a reduced component of complex III of the mitochondrial respiratory chain, particularly when antimycin A is present. Although it is generally believed that ubisemiquinone is the electron donor to O2, little experimental evidence supporting this view has been reported. Experiments with succinate as electron donor in the presence of antimycin A in intact rat heart mitochondria, which contain much superoxide dismutase but little catalase, showed that myxothiazol, which inhibits reduction of the Rieske iron-sulfur center, prevented formation of hydrogen peroxide, determined spectrophotometrically as the H2O2-peroxidase complex. Similarly, depletion of the mitochondria of their cytochrome c also inhibited formation of H2O2, which was restored by addition of cytochrome c. These observations indicate that factors preventing the formation of ubisemiquinone also prevent H2O2 formation. They also exclude ubiquinol, which remains reduced under these conditions, as the reductant of O2. Since cytochrome b also remains fully reduced when myxothiazol is added to succinate- and antimycin A-supplemented mitochondria, reduced cytochrome b may also be excluded as the reductant of O2. These observations, which are consistent with the Q-cycle reactions, by exclusion of other possibilities leave ubisemiquinone as the only reduced electron carrier in complex III capable of reducing O2 to O2-.

  18. Proton coupled electron transfer from the excited state of a ruthenium(II) pyridylimidazole complex.

    PubMed

    Pannwitz, Andrea; Wenger, Oliver S

    2016-04-28

    Proton coupled electron transfer (PCET) from the excited state of [Ru(bpy)2pyimH](2+) (bpy = 2,2'-bipyridine; pyimH = 2-(2'-pyridyl)imidazole) to N-methyl-4,4'-bipyridinium (monoquat, MQ(+)) was studied. While this complex has been investigated previously, our study is the first to show that the formal bond dissociation free energy (BDFE) of the imidazole-N-H bond decreases from (91 ± 1) kcal mol(-1) in the electronic ground state to (43 ± 5) kcal mol(-1) in the lowest-energetic (3)MLCT excited state. This makes the [Ru(bpy)2pyimH](2+) complex a very strong (formal) hydrogen atom donor even when compared to metal hydride complexes, and this is interesting for light-driven (formal) hydrogen atom transfer (HAT) reactions with a variety of different substrates. Mechanistically, formal HAT between (3)MLCT excited [Ru(bpy)2pyimH](2+) and monoquat in buffered 1 : 1 (v : v) CH3CN/H2O was found to occur via a sequence of reaction steps involving electron transfer from Ru(ii) to MQ(+) coupled to release of the N-H proton to buffer base, followed by protonation of reduced MQ(+) by buffer acid. Our study is relevant in the larger contexts of photoredox catalysis and light-to-chemical energy conversion.

  19. Exploring the Interaction Natures in Plutonyl (VI) Complexes with Topological Analyses of Electron Density

    PubMed Central

    Du, Jiguang; Sun, Xiyuan; Jiang, Gang

    2016-01-01

    The interaction natures between Pu and different ligands in several plutonyl (VI) complexes are investigated by performing topological analyses of electron density. The geometrical structures in both gaseous and aqueous phases are obtained with B3LYP functional, and are generally in agreement with available theoretical and experimental results when combined with all-electron segmented all-electron relativistic contracted (SARC) basis set. The Pu–Oyl bond orders show significant linear dependence on bond length and the charge of oxygen atoms in plutonyl moiety. The closed-shell interactions were identified for Pu-Ligand bonds in most complexes with quantum theory of atoms in molecules (QTAIM) analyses. Meanwhile, we found that some Pu–Ligand bonds, like Pu–OH−, show weak covalent. The interactive nature of Pu–ligand bonds were revealed based on the interaction quantum atom (IQA) energy decomposition approach, and our results indicate that all Pu–Ligand interactions is dominated by the electrostatic attraction interaction as expected. Meanwhile it is also important to note that the quantum mechanical exchange-correlation contributions can not be ignored. By means of the non-covalent interaction (NCI) approach it has been found that some weak and repulsion interactions existed in plutonyl(VI) complexes, which can not be distinguished by QTAIM, can be successfully identified. PMID:27077844

  20. Electronic Structure Determination of Pyridine N-Heterocyclic Carbene Iron Dinitrogen Complexes and Neutral Ligand Derivatives

    PubMed Central

    2015-01-01

    The electronic structures of pyridine N-heterocyclic dicarbene (iPrCNC) iron complexes have been studied by a combination of spectroscopic and computational methods. The goal of these studies was to determine if this chelate engages in radical chemistry in reduced base metal compounds. The iron dinitrogen example (iPrCNC)Fe(N2)2 and the related pyridine derivative (iPrCNC)Fe(DMAP)(N2) were studied by NMR, Mössbauer, and X-ray absorption spectroscopy and are best described as redox non-innocent compounds with the iPrCNC chelate functioning as a classical π acceptor and the iron being viewed as a hybrid between low-spin Fe(0) and Fe(II) oxidation states. This electronic description has been supported by spectroscopic data and DFT calculations. Addition of N,N-diallyl-tert-butylamine to (iPrCNC)Fe(N2)2 yielded the corresponding iron diene complex. Elucidation of the electronic structure again revealed the CNC chelate acting as a π acceptor with no evidence for ligand-centered radicals. This ground state is in contrast with the case for the analogous bis(imino)pyridine iron complexes and may account for the lack of catalytic [2π + 2π] cycloaddition reactivity. PMID:25328270

  1. Electron collisions with the CH{sub 2}O-H{sub 2}O complex

    SciTech Connect

    Freitas, T. C.; Lima, M. A. P.; Canuto, S.; Bettega, M. H. F.

    2009-12-15

    We report cross sections for elastic collisions of low-energy electrons with the CH{sub 2}O-H{sub 2}O complex. We employed the Schwinger multichannel method with pseudopotentials in the static-exchange and in the static-exchange-polarization approximations for energies from 0.1 to 20 eV. We considered four different hydrogen-bonded structures for the complex that were generated by classical Monte Carlo simulations. Our aim is to investigate the effect of the water molecule on the pi* shape resonance of formaldehyde. Previous studies reported a pi* shape resonance for CH{sub 2}O at around 1 eV. The resonance positions of the complexes appear at lower energies in all cases due to the mutual polarization between the two molecules. This indicates that the presence of water may favor dissociation by electron impact and may lead to an important effect on strand breaking in wet DNA by electron impact.

  2. Electron molecular beam epitaxy: Layer-by-layer growth of complex oxides via pulsed electron-beam deposition

    SciTech Connect

    Comes, Ryan; Liu Hongxue; Lu Jiwei; Gu, Man; Khokhlov, Mikhail; Wolf, Stuart A.

    2013-01-14

    Complex oxide epitaxial film growth is a rich and exciting field, owing to the wide variety of physical properties present in oxides. These properties include ferroelectricity, ferromagnetism, spin-polarization, and a variety of other correlated phenomena. Traditionally, high quality epitaxial oxide films have been grown via oxide molecular beam epitaxy or pulsed laser deposition. Here, we present the growth of high quality epitaxial films using an alternative approach, the pulsed electron-beam deposition technique. We demonstrate all three epitaxial growth modes in different oxide systems: Frank-van der Merwe (layer-by-layer); Stranski-Krastanov (layer-then-island); and Volmer-Weber (island). Analysis of film quality and morphology is presented and techniques to optimize the morphology of films are discussed.

  3. Defect control of conventional and anomalous electron transport at complex oxide interfaces

    DOE PAGES

    Gunkel, F.; Bell, Chris; Inoue, Hisashi; ...

    2016-08-30

    Using low-temperature electrical measurements, the interrelation between electron transport, magnetic properties, and ionic defect structure in complex oxide interface systems is investigated, focusing on NdGaO3/SrTiO3 (100) interfaces. Field-dependent Hall characteristics (2–300 K) are obtained for samples grown at various growth pressures. In addition to multiple electron transport, interfacial magnetism is tracked exploiting the anomalous Hall effect (AHE). These two properties both contribute to a nonlinearity in the field dependence of the Hall resistance, with multiple carrier conduction evident below 30 K and AHE at temperatures ≲10 K. Considering these two sources of nonlinearity, we suggest a phenomenological model capturing themore » complex field dependence of the Hall characteristics in the low-temperature regime. Our model allows the extraction of the conventional transport parameters and a qualitative analysis of the magnetization. The electron mobility is found to decrease systematically with increasing growth pressure. This suggests dominant electron scattering by acceptor-type strontium vacancies incorporated during growth. The AHE scales with growth pressure. In conclusion, the most pronounced AHE is found at increased growth pressure and, thus, in the most defective, low-mobility samples, indicating a correlation between transport, magnetism, and cation defect concentration.« less

  4. Quantum transport in molecular electronic devices described with complex source and sink potentials

    NASA Astrophysics Data System (ADS)

    Goyer, Francois; Goker, Ali; Ernzerhof, Matthias

    2008-03-01

    We present a non-Hermitian model Hamiltonian containing complex potentials [1,2] that is devised to study ballistic transport in molecular electronic devices (MEDs). The complex potentials replace semi-infinite contacts and act as source and sink of probability current density. This approach is rigorous in the sense that the exact wave function is recovered in the interior of the MED. We employ this technique to calculate the conductance through certain prototypical MEDs [3]. We also extend this method [4] such that we can go beyond the one- electron picture by constructing two-electron states explicitly. We present results for simple model system described by Hubbard-type Hamiltonians. The impact of electron correlation effects on the molecular conductance is discussed. [1] F. Goyer, M. Ernzerhof, M. Zhuang, JCP, 126, 144104 (2007). [2] M. Ernzerhof, JCP, to appear nov. 2007. [3] M. Ernzerhof, H. Bahmann, F. Goyer, M. Zhuang, P. Rocheleau, J. Chem. Theory Comput., 2, 1291 (2006); M. Ernzerhof, M. Zhuang, P. Rocheleau, JCP, 123, 134704 (2005). [4] A. Goker, F. Goyer, M. Ernzerhof, work in pogress.

  5. Molecular and electronic structure of terminal and alkali metal-capped uranium(V) nitride complexes

    NASA Astrophysics Data System (ADS)

    King, David M.; Cleaves, Peter A.; Wooles, Ashley J.; Gardner, Benedict M.; Chilton, Nicholas F.; Tuna, Floriana; Lewis, William; McInnes, Eric J. L.; Liddle, Stephen T.

    2016-12-01

    Determining the electronic structure of actinide complexes is intrinsically challenging because inter-electronic repulsion, crystal field, and spin-orbit coupling effects can be of similar magnitude. Moreover, such efforts have been hampered by the lack of structurally analogous families of complexes to study. Here we report an improved method to U≡N triple bonds, and assemble a family of uranium(V) nitrides. Along with an isoelectronic oxo, we quantify the electronic structure of this 5f1 family by magnetometry, optical and electron paramagnetic resonance (EPR) spectroscopies and modelling. Thus, we define the relative importance of the spin-orbit and crystal field interactions, and explain the experimentally observed different ground states. We find optical absorption linewidths give a potential tool to identify spin-orbit coupled states, and show measurement of UV...UV super-exchange coupling in dimers by EPR. We show that observed slow magnetic relaxation occurs via two-phonon processes, with no obvious correlation to the crystal field.

  6. Molecular and electronic structure of terminal and alkali metal-capped uranium(V) nitride complexes

    PubMed Central

    King, David M.; Cleaves, Peter A.; Wooles, Ashley J.; Gardner, Benedict M.; Chilton, Nicholas F.; Tuna, Floriana; Lewis, William; McInnes, Eric J. L.; Liddle, Stephen T.

    2016-01-01

    Determining the electronic structure of actinide complexes is intrinsically challenging because inter-electronic repulsion, crystal field, and spin–orbit coupling effects can be of similar magnitude. Moreover, such efforts have been hampered by the lack of structurally analogous families of complexes to study. Here we report an improved method to U≡N triple bonds, and assemble a family of uranium(V) nitrides. Along with an isoelectronic oxo, we quantify the electronic structure of this 5f1 family by magnetometry, optical and electron paramagnetic resonance (EPR) spectroscopies and modelling. Thus, we define the relative importance of the spin–orbit and crystal field interactions, and explain the experimentally observed different ground states. We find optical absorption linewidths give a potential tool to identify spin–orbit coupled states, and show measurement of UV···UV super-exchange coupling in dimers by EPR. We show that observed slow magnetic relaxation occurs via two-phonon processes, with no obvious correlation to the crystal field. PMID:27996007

  7. Defect Control of Conventional and Anomalous Electron Transport at Complex Oxide Interfaces

    NASA Astrophysics Data System (ADS)

    Gunkel, F.; Bell, Chris; Inoue, Hisashi; Kim, Bongju; Swartz, Adrian G.; Merz, Tyler A.; Hikita, Yasuyuki; Harashima, Satoshi; Sato, Hiroki K.; Minohara, Makoto; Hoffmann-Eifert, Susanne; Dittmann, Regina; Hwang, Harold Y.

    2016-07-01

    Using low-temperature electrical measurements, the interrelation between electron transport, magnetic properties, and ionic defect structure in complex oxide interface systems is investigated, focusing on NdGaO3 /SrTiO3 (100) interfaces. Field-dependent Hall characteristics (2-300 K) are obtained for samples grown at various growth pressures. In addition to multiple electron transport, interfacial magnetism is tracked exploiting the anomalous Hall effect (AHE). These two properties both contribute to a nonlinearity in the field dependence of the Hall resistance, with multiple carrier conduction evident below 30 K and AHE at temperatures ≲10 K . Considering these two sources of nonlinearity, we suggest a phenomenological model capturing the complex field dependence of the Hall characteristics in the low-temperature regime. Our model allows the extraction of the conventional transport parameters and a qualitative analysis of the magnetization. The electron mobility is found to decrease systematically with increasing growth pressure. This suggests dominant electron scattering by acceptor-type strontium vacancies incorporated during growth. The AHE scales with growth pressure. The most pronounced AHE is found at increased growth pressure and, thus, in the most defective, low-mobility samples, indicating a correlation between transport, magnetism, and cation defect concentration.

  8. Influence of Copper Oxidation State on the Bonding and Electronic Structure of Cobalt–Copper Complexes

    SciTech Connect

    Eisenhart, Reed J.; Carlson, Rebecca K.; Clouston, Laura J.; Young, Victor G.; Chen, Yu-Sheng; Bill, Eckhard; Gagliardi, Laura; Lu, Connie C.

    2015-12-07

    Heterobimetallic complexes that pair cobalt and copper were synthesized and characterized by a suite of physical methods, including X-ray diffraction, X-ray anomalous scattering, cyclic voltammetry, magnetometry, electronic absorption spectroscopy, electron paramagnetic resonance, and quantum chemical methods. Both Cu(II) and Cu(I) reagents were independently added to a Co(II) metalloligand to provide (py3tren)CoCuCl (1-Cl) and (py3tren)CoCu(CH3CN) (2-CH3CN), respectively, where py3tren is the triply deprotonated form of N,N,N-tris(2-(2-pyridylamino)ethyl)amine. Complex 2-CH3CN can lose the acetonitrile ligand to generate a coordination polymer consistent with the formula “(py3tren)CoCu” (2). One-electron chemical oxidation of 2-CH3CN with AgOTf generated (py3tren)CoCuOTf (1-OTf). The Cu(II)/Cu(I) redox couple for 1-OTf and 2-CH3CN is reversible at -0.56 and -0.33 V vs Fc+/Fc, respectively. The copper oxidation state impacts the electronic structure of the heterobimetallic core, as well as the nature of the Co–Cu interaction. Quantum chemical calculations showed modest electron delocalization in the (CoCu)+4 state via a Co–Cu σ bond that is weakened by partial population of the Co–Cu σ antibonding orbital. By contrast, no covalent Co–Cu bonding is predicted for the (CoCu)+3 analogue, and the d-electrons are fully localized at individual metals.

  9. Influence of Copper Oxidation State on the Bonding and Electronic Structure of Cobalt-Copper Complexes

    SciTech Connect

    Eisenhart, Reed J.; Carlson, Rebecca K.; Clouston, Laura J.; Victor G. Young Jr.; Chen, Yu-Sheng; Bill, Eckhard; Gagliardi, Laura; Lu, Connie C.

    2016-03-04

    Heterobimetallic complexes that pair cobalt and copper were synthesized and characterized by a suite of physical methods, including X-ray diffraction, X-ray anomalous scattering, cyclic voltammetry, magnetometry, electronic absorption spectroscopy, electron paramagnetic resonance, and quantum chemical methods. Both Cu(II) and Cu(I) reagents were independently added to a Co(II) metalloligand to provide (py3tren)CoCuCl (1-Cl) and (py3tren)CoCu(CH3CN) (2-CH3CN), respectively, where py3tren is the triply deprotonated form of N,N,N-tris(2-(2-pyridylamino)ethyl)amine. Complex 2-CH3CN can lose the acetonitrile ligand to generate a coordination polymer consistent with the formula “(py3tren)CoCu” (2). One-electron chemical oxidation of 2-CH3CN with AgOTf generated (py3tren)CoCuOTf (1-OTf). The Cu(II)/Cu(I) redox couple for 1-OTf and 2-CH3CN is reversible at -0.56 and -0.33 V vs Fc+/Fc, respectively. The copper oxidation state impacts the electronic structure of the heterobimetallic core, as well as the nature of the Co–Cu interaction. Quantum chemical calculations showed modest electron delocalization in the (CoCu)+4 state via a Co–Cu σ bond that is weakened by partial population of the Co–Cu σ antibonding orbital. By contrast, no covalent Co–Cu bonding is predicted for the (CoCu)+3 analogue, and the d-electrons are fully localized at individual metals.

  10. Solution Photophysics, One-Electron Photooxidation, and Photoinitiated Two-Electron Oxidation of Molybdenum(III) Complexes.

    PubMed

    Mohammed, Abdul K.; Isovitsch, Ralph A.; Maverick, Andrew W.

    1998-06-01

    Several six-coordinate Mo(III) complexes phosphoresce and undergo photooxidation in room-temperature solution. The phosphorescence of (Me(3)[9]aneN(3))MoX(3) (Me(3)[9]aneN(3) = 1,4,7-trimethyl-1,4,7-triazacyclononane) in CH(3)CN at room temperature occurs with the following maxima, lifetimes, and quantum yields: X = Cl, 1120 nm, 1.0 &mgr;s, and 6.1 x 10(-)(5); X = Br, 1130 nm, 0.80 &mgr;s, and 9.6 x 10(-)(5); and X = I, 1160 nm, 0.40 &mgr;s, and 1.2 x 10(-)(4), respectively. The phosphorescences are assigned to the {(2)E(g), (2)T(1g)} --> (4)A(2g) transition. Solutions of HB(Me(2)pz)(3)Mo(III)Cl(3)(-) Me(2)pzH = 3,5-dimethylpyrazole) in CH(3)CN, and solid MoCl(3)(py)(3) and (Me(3)[9]aneN(3))WCl(3), also phosphoresce. (Me(3)[9]aneN(3))MoX(3) (X = Cl, Br, I) complexes undergo reversible one-electron photooxidation upon irradiation in the presence of acceptors such as TCNE and chloranil. (Me(3)[9]aneN(3))MoX(3) (X = Br, I only) are photooxidized irreversibly to [(Me(3)[9]aneN(3))Mo(IV)X(3)](+) by C(NO(2))(4) in CH(3)CN. In CH(3)CN-H(2)O (1:1 v/v), photoinitiated two-electron oxidation occurs: the primary photoproduct is Mo(IV), which disproportionates spontaneously to form [(Me(3)[9]aneN(3))Mo(V)OX(2)](+).

  11. CC-LR: Providing Interactive, Challenging and Attractive Collaborative Complex Learning Resources

    ERIC Educational Resources Information Center

    Caballé, S.; Mora, N.; Feidakis, M.; Gañán, D.; Conesa, J.; Daradoumis, T.; Prieto, J.

    2014-01-01

    Many researchers argue that students must be meaningfully engaged in the learning resources for effective learning to occur. However, current online learners still report a problematic lack of attractive and challenging learning resources that engage them in the learning process. This endemic problem is even more evident in online collaborative…

  12. Complex genetic effects on early vegetative development shape resource allocation differences between Arabidopsis lyrata populations.

    PubMed

    Remington, David L; Leinonen, Päivi H; Leppälä, Johanna; Savolainen, Outi

    2013-11-01

    Costs of reproduction due to resource allocation trade-offs have long been recognized as key forces in life history evolution, but little is known about their functional or genetic basis. Arabidopsis lyrata, a perennial relative of the annual model plant A. thaliana with a wide climatic distribution, has populations that are strongly diverged in resource allocation. In this study, we evaluated the genetic and functional basis for variation in resource allocation in a reciprocal transplant experiment, using four A. lyrata populations and F2 progeny from a cross between North Carolina (NC) and Norway parents, which had the most divergent resource allocation patterns. Local alleles at quantitative trait loci (QTL) at a North Carolina field site increased reproductive output while reducing vegetative growth. These QTL had little overlap with flowering date QTL. Structural equation models incorporating QTL genotypes and traits indicated that resource allocation differences result primarily from QTL effects on early vegetative growth patterns, with cascading effects on later vegetative and reproductive development. At a Norway field site, North Carolina alleles at some of the same QTL regions reduced survival and reproductive output components, but these effects were not associated with resource allocation trade-offs in the Norway environment. Our results indicate that resource allocation in perennial plants may involve important adaptive mechanisms largely independent of flowering time. Moreover, the contributions of resource allocation QTL to local adaptation appear to result from their effects on developmental timing and its interaction with environmental constraints, and not from simple models of reproductive costs.

  13. CC-LR: Providing Interactive, Challenging and Attractive Collaborative Complex Learning Resources

    ERIC Educational Resources Information Center

    Caballé, S.; Mora, N.; Feidakis, M.; Gañán, D.; Conesa, J.; Daradoumis, T.; Prieto, J.

    2014-01-01

    Many researchers argue that students must be meaningfully engaged in the learning resources for effective learning to occur. However, current online learners still report a problematic lack of attractive and challenging learning resources that engage them in the learning process. This endemic problem is even more evident in online collaborative…

  14. Complex Genetic Effects on Early Vegetative Development Shape Resource Allocation Differences Between Arabidopsis lyrata Populations

    PubMed Central

    Remington, David L.; Leinonen, Päivi H.; Leppälä, Johanna; Savolainen, Outi

    2013-01-01

    Costs of reproduction due to resource allocation trade-offs have long been recognized as key forces in life history evolution, but little is known about their functional or genetic basis. Arabidopsis lyrata, a perennial relative of the annual model plant A. thaliana with a wide climatic distribution, has populations that are strongly diverged in resource allocation. In this study, we evaluated the genetic and functional basis for variation in resource allocation in a reciprocal transplant experiment, using four A. lyrata populations and F2 progeny from a cross between North Carolina (NC) and Norway parents, which had the most divergent resource allocation patterns. Local alleles at quantitative trait loci (QTL) at a North Carolina field site increased reproductive output while reducing vegetative growth. These QTL had little overlap with flowering date QTL. Structural equation models incorporating QTL genotypes and traits indicated that resource allocation differences result primarily from QTL effects on early vegetative growth patterns, with cascading effects on later vegetative and reproductive development. At a Norway field site, North Carolina alleles at some of the same QTL regions reduced survival and reproductive output components, but these effects were not associated with resource allocation trade-offs in the Norway environment. Our results indicate that resource allocation in perennial plants may involve important adaptive mechanisms largely independent of flowering time. Moreover, the contributions of resource allocation QTL to local adaptation appear to result from their effects on developmental timing and its interaction with environmental constraints, and not from simple models of reproductive costs. PMID:23979581

  15. A different 'spin' on rhenium chemistry. synthetic approaches and perspectives of 17-electron rhenium complexes.

    PubMed

    Zobi, Fabio

    2010-01-01

    Transition metal complexes of rhenium and technetium find wide application in nuclear medicine and the chemistry of these elements is still the focus of intense research efforts. For therapeutic and diagnostic applications, currently much attention is dedicated to the development of new targeting strategies aimed at appending the metal complexes to biological vectors (e.g. a peptide) for a site-specific delivery of the radionuclides. Advancements in radiopharmacy, however, will not only arise from the development of new targeted strategies but also from the exploration of the chemistry of these elements in their unusual oxidation states. In this respect the even number oxidation states of Re and Tc (i.e. +II, +IV and +VI) are relatively poorly understood. In particular, stable and substitutionally labile mononuclear 17-electron species of the elements (+II, d(5)) are a rarely encountered class of complexes. In this review we present our recent developments in the field of rhenium (II) chemistry with emphasis on the novel synthetic strategies we have recently introduced. We will also describe how the unique chemical and electronic properties of Re(II)-based complexes may provide a potentially new approach for applications in inorganic medicinal chemistry.

  16. Cardiolipin promotes electron transport between ubiquinone and complex I to rescue PINK1 deficiency.

    PubMed

    Vos, Melissa; Geens, Ann; Böhm, Claudia; Deaulmerie, Liesbeth; Swerts, Jef; Rossi, Matteo; Craessaerts, Katleen; Leites, Elvira P; Seibler, Philip; Rakovic, Aleksandar; Lohnau, Thora; De Strooper, Bart; Fendt, Sarah-Maria; Morais, Vanessa A; Klein, Christine; Verstreken, Patrik

    2017-03-06

    PINK1 is mutated in Parkinson's disease (PD), and mutations cause mitochondrial defects that include inefficient electron transport between complex I and ubiquinone. Neurodegeneration is also connected to changes in lipid homeostasis, but how these are related to PINK1-induced mitochondrial dysfunction is unknown. Based on an unbiased genetic screen, we found that partial genetic and pharmacological inhibition of fatty acid synthase (FASN) suppresses toxicity induced by PINK1 deficiency in flies, mouse cells, patient-derived fibroblasts, and induced pluripotent stem cell-derived dopaminergic neurons. Lower FASN activity in PINK1 mutants decreases palmitate levels and increases the levels of cardiolipin (CL), a mitochondrial inner membrane-specific lipid. Direct supplementation of CL to isolated mitochondria not only rescues the PINK1-induced complex I defects but also rescues the inefficient electron transfer between complex I and ubiquinone in specific mutants. Our data indicate that genetic or pharmacologic inhibition of FASN to increase CL levels bypasses the enzymatic defects at complex I in a PD model.

  17. Ferrocene-o-benzosemiquinonato tin(IV) electron-transfer complexes.

    PubMed

    Ilyakina, Ekaterina V; Poddel'sky, Andrey I; Fukin, Georgy K; Bogomyakov, Artem S; Cherkasov, Vladimir K; Abakumov, Gleb A

    2013-05-06

    The interaction of ferrocene with tin(IV) o-benzosemiquinonato complexes in acetonitrile results in a reversible electron transfer (ET) from ferrocene to the redox-active ligand with the formation of electron-transfer complexes [(3,6-Cat)SnBr3](-)[Cp2Fe](+) (1) and [(3,6-Cat)(3,6-SQ)SnCl2](-)[Cp2Fe](+) (2), where 3,6-Cat is the 3,6-di-tert-butyl-catecholate dianion and 3,6-SQ is the 3,6-di-tert-butyl-o-benzosemiquinonato radical anion. The ET process and the solvent effect in the system "ferrocene-o-benzosemiquinonato tin(IV) complexes" were investigated on the basis of a combination of spectroscopic and X-ray diffraction methods. The molecular structures of 1 and 2 were confirmed by X-ray analysis. Complex 2 demonstrates the ferromagnetic coupling in the linear chain alternating ···D(+•)A(-•)D(+•)A(-•)··· motif.

  18. Cannabinoid-Induced Changes in the Activity of Electron Transport Chain Complexes of Brain Mitochondria.

    PubMed

    Singh, Namrata; Hroudová, Jana; Fišar, Zdeněk

    2015-08-01

    The aim of this study was to investigate changes in the activity of individual mitochondrial respiratory chain complexes (I, II/III, IV) and citrate synthase induced by pharmacologically different cannabinoids. In vitro effects of selected cannabinoids on mitochondrial enzymes were measured in crude mitochondrial fraction isolated from pig brain. Both cannabinoid receptor agonists, Δ(9)-tetrahydrocannabinol, anandamide, and R-(+)-WIN55,212-2, and antagonist/inverse agonists of cannabinoid receptors, AM251, and cannabidiol were examined in pig brain mitochondria. Different effects of these cannabinoids on mitochondrial respiratory chain complexes and citrate synthase were found. Citrate synthase activity was decreased only by Δ(9)-tetrahydrocannabinol and AM251. Significant increase in the complex I activity was induced by anandamide. At micromolar concentration, all the tested cannabinoids inhibited the activity of electron transport chain complexes II/III and IV. Stimulatory effect of anandamide on activity of complex I may participate on distinct physiological effects of endocannabinoids compared to phytocannabinoids or synthetic cannabinoids. Common inhibitory effect of cannabinoids on activity of complex II/III and IV confirmed a non-receptor-mediated mechanism of cannabinoid action on individual components of system of oxidative phosphorylation.

  19. Challenges in the implementation of an electronic surveillance system in a resource-limited setting: Alerta, in Peru

    PubMed Central

    Soto, Giselle; Araujo-Castillo, Roger V; Neyra, Joan; Fernandez, Miguel; Leturia, Carlos; Mundaca, Carmen C; Blazes, David L

    2008-01-01

    Background Infectious disease surveillance is a primary public health function in resource-limited settings. In 2003, an electronic disease surveillance system (Alerta) was established in the Peruvian Navy with support from the U.S. Naval Medical Research Center Detachment (NMRCD). Many challenges arose during the implementation process, and a variety of solutions were applied. The purpose of this paper is to identify and discuss these issues. Methods This is a retrospective description of the Alerta implementation. After a thoughtful evaluation according to the Centers for Disease Control and Prevention (CDC) guidelines, the main challenges to implementation were identified and solutions were devised in the context of a resource-limited setting, Peru. Results After four years of operation, we have identified a number of challenges in implementing and operating this electronic disease surveillance system. These can be divided into the following categories: (1) issues with personnel and stakeholders; (2) issues with resources in a developing setting; (3) issues with processes involved in the collection of data and operation of the system; and (4) issues with organization at the central hub. Some of the challenges are unique to resource-limited settings, but many are applicable for any surveillance system. For each of these challenges, we developed feasible solutions that are discussed. Conclusion There are many challenges to overcome when implementing an electronic disease surveillance system, not only related to technology issues. A comprehensive approach is required for success, including: technical support, personnel management, effective training, and cultural sensitivity in order to assure the effective deployment of an electronic disease surveillance system. PMID:19025681

  20. Three-dimensional structure of human chromatin accessibility complex hCHRAC by electron microscopy

    SciTech Connect

    Hu, M.; Hainfeld, J.; Zhang, Y.-B.; Qian, L.; Brinas, R. P.; Kuznetsova, L.

    2008-12-01

    ATP-dependent chromatin remodeling complexes modulate the dynamic assembly and remodeling of chromatin involved in DNA transcription, replication, and repair. There is little structural detail known about these important multiple-subunit enzymes that catalyze chromatin remodeling processes. Here we report a three-dimensional structure of the human chromatin accessibility complex, hCHRAC, using single particle reconstruction by negative stain electron microscopy. This structure shows an asymmetric 15 x 10 x 12 nm disk shape with several lobes protruding out of its surfaces. Based on the factors of larger contact area, smaller steric hindrance, and direct involvement of hCHRAC in interactions with the nucleosome, we propose that four lobes on one side form a multiple-site contact surface 10 nm in diameter for nucleosome binding. This work provides the first determination of the three-dimensional structure of the ISWI-family of chromatin remodeling complexes.

  1. Proton and Electron Additions to Iron (II) Dinitrogen Complexes Containing Pendant Amines

    SciTech Connect

    Heiden, Zachariah M.; Chen, Shentan; Labios, Liezel AN; Bullock, R. Morris; Walter, Eric D.; Tyson, Elizabeth L.; Mock, Michael T.

    2014-03-10

    We describe a single site cis-(H)FeII-N2 complex, generated by the protonation of an iron-carbon bond of a "reduced" iron complex, that models key aspects of proposed protonated intermediates of the E4 state of nitrogenase. The influence on N2 binding from the addition of protons to the pendant amine sites in the second coordination sphere is described. Furthermore, the addition of electrons to the protonated complexes results in H2 loss. The mechanism of H2 loss is explored to draw a parallel to the origin of H2 loss (homolytic or heterolytic) and the nature of N2 coordination in intermediates of the E4 state of nitrogenase.

  2. Complex Observation in Electron Microscopy. II. Direct Visualization of Phases and Amplitudes of Exit Wave Functions

    NASA Astrophysics Data System (ADS)

    Danev, Radostin; Nagayama, Kuniaki

    2001-03-01

    We report microscopic observation of complex waves emitted from objects. Two images sequentially detected at the image plane with two transmission electron microscopic (TEM) methods, the conventional and the phase-contrasted, are numerically combined to reproduce complex wave functions, which are holding complete optical information. The long lasting issue in conventional TEM that the contrast and the resolution of images are difficult to be simultaneously optimized was settled with the complex wave functions. The aberration-corrected phase images of ferritin (at 400 kV) and TMV (at 100 kV) did show an extraordinary high contrast free from image distortion without sacrificing the resolution compared with that obtained by conventional TEM.

  3. Determination of electronic ground state properties of a dinuclear iron(II) spin crossover complex

    NASA Astrophysics Data System (ADS)

    Bauer, T. O.; Schmitz, M.; Graf, M.; Kelm, H.; Krüger, H.-J.; Schünemann, V.

    2016-12-01

    The dinuclear complex [(Fe(L-N4Me2))2(BiBzIm)](ClO4)2ṡ2EtCN (1) has been investigated by Mössbauer spectroscopy carried out in the temperature range from 5 to 150 K with externally applied magnetic fields of up to B = 5 T. By means of a consistent simulation of all experimental data sets within the Spin Hamiltonian formalism, the zero-field splitting D and the rhombicity parameter E/ D of the ferrous high-spin (HS) site in this complex was determined to be D = -15.0 ± 1.0 cm-1 and E/ D = 0.33 respectively. The sign of the quadrupole splitting of the HS site is positive which indicates that this iron site of the dinuclear complex 1 has an electronic ground state with the dxy orbital being twofold occupied.

  4. Localized reconstruction of subunits from electron cryomicroscopy images of macromolecular complexes

    PubMed Central

    Ilca, Serban L.; Kotecha, Abhay; Sun, Xiaoyu; Poranen, Minna M.; Stuart, David I.; Huiskonen, Juha T.

    2015-01-01

    Electron cryomicroscopy can yield near-atomic resolution structures of highly ordered macromolecular complexes. Often however some subunits bind in a flexible manner, have different symmetry from the rest of the complex, or are present in sub-stoichiometric amounts, limiting the attainable resolution. Here we report a general method for the localized three-dimensional reconstruction of such subunits. After determining the particle orientations, local areas corresponding to the subunits can be extracted and treated as single particles. We demonstrate the method using three examples including a flexible assembly and complexes harbouring subunits with either partial occupancy or mismatched symmetry. Most notably, the method allows accurate fitting of the monomeric RNA-dependent RNA polymerase bound at the threefold axis of symmetry inside a viral capsid, revealing for the first time its exact orientation and interactions with the capsid proteins. Localized reconstruction is expected to provide novel biological insights in a range of challenging biological systems. PMID:26534841

  5. Brain region-specific deficit in mitochondrial electron transport chain complexes in children with autism

    PubMed Central

    Chauhan, Abha; Gu, Feng; Essa, Musthafa M.; Wegiel, Jerzy; Kaur, Kulbir; Brown, William Ted; Chauhan, Ved

    2016-01-01

    Mitochondria play important roles in generation of free radicals, ATP formation, and in apoptosis. We studied the levels of mitochondrial electron transport chain (ETC) complexes, that is, complexes I, II, III, IV, and V, in brain tissue samples from the cerebellum and the frontal, parietal, occipital, and temporal cortices of subjects with autism and age-matched control subjects. The subjects were divided into two groups according to their ages: Group A (children, ages 4–10 years) and Group B (adults, ages 14–39 years). In Group A, we observed significantly lower levels of complexes III and V in the cerebellum (p < 0.05), of complex I in the frontal cortex (p < 0.05), and of complexes II (p < 0.01), III (p<0.01), and V (p < 0.05) in the temporal cortex of children with autism as compared to age-matched control subjects, while none of the five ETC complexes was affected in the parietal and occipital cortices in subjects with autism. In the cerebellum and temporal cortex, no overlap was observed in the levels of these ETC complexes between subjects with autism and control subjects. In the frontal cortex of Group A, a lower level of ETC complexes was observed in a subset of autism cases, that is, 60% (3/5) for complexes I, II, and V, and 40% (2/5) for complexes III and IV. A striking observation was that the levels of ETC complexes were similar in adult subjects with autism and control subjects (Group B). A significant increase in the levels of lipid hydroperoxides, an oxidative stress marker, was also observed in the cerebellum and temporal cortex in the children with autism. These results suggest that the expression of ETC complexes is decreased in the cerebellum and the frontal and temporal regions of the brain in children with autism, which may lead to abnormal energy metabolism and oxidative stress. The deficits observed in the levels of ETC complexes in children with autism may readjust to normal levels by adulthood. PMID:21250997

  6. Electron-transfer reduction of dinuclear copper peroxo and bis-μ-oxo complexes leading to the catalytic four-electron reduction of dioxygen to water.

    PubMed

    Tahsini, Laleh; Kotani, Hiroaki; Lee, Yong-Min; Cho, Jaeheung; Nam, Wonwoo; Karlin, Kenneth D; Fukuzumi, Shunichi

    2012-01-23

    The four-electron reduction of dioxygen by decamethylferrocene (Fc*) to water is efficiently catalyzed by a binuclear copper(II) complex (1) and a mononuclear copper(II) complex (2) in the presence of trifluoroacetic acid in acetone at 298 K. Fast electron transfer from Fc* to 1 and 2 affords the corresponding Cu(I) complexes, which react at low temperature (193 K) with dioxygen to afford the η(2):η(2)-peroxo dicopper(II) (3) and bis-μ-oxo dicopper(III) (4) intermediates, respectively. The rate constants for electron transfer from Fc* and octamethylferrocene (Me(8)Fc) to 1 as well as electron transfer from Fc* and Me(8)Fc to 3 were determined at various temperatures, leading to activation enthalpies and entropies. The activation entropies of electron transfer from Fc* and Me(8)Fc to 1 were determined to be close to zero, as expected for outer-sphere electron-transfer reactions without formation of any intermediates. For electron transfer from Fc* and Me(8)Fc to 3, the activation entropies were also found to be close to zero. Such agreement indicates that the η(2):η(2)-peroxo complex (3) is directly reduced by Fc* rather than via the conversion to the corresponding bis-μ-oxo complex, followed by the electron-transfer reduction by Fc* leading to the four-electron reduction of dioxygen to water. The bis-μ-oxo species (4) is reduced by Fc* with a much faster rate than the η(2):η(2)-peroxo complex (3), but this also leads to the four-electron reduction of dioxygen to water. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Steric and Electronic Influence on Proton-Coupled Electron-Transfer Reactivity of a Mononuclear Mn(III)-Hydroxo Complex.

    PubMed

    Rice, Derek B; Wijeratne, Gayan B; Burr, Andrew D; Parham, Joshua D; Day, Victor W; Jackson, Timothy A

    2016-08-15

    A mononuclear hydroxomanganese(III) complex was synthesized utilizing the N5 amide-containing ligand 2-[bis(pyridin-2-ylmethyl)]amino-N-2-methyl-quinolin-8-yl-acetamidate (dpaq(2Me) ). This complex is similar to previously reported [Mn(III)(OH)(dpaq(H))](+) [Inorg. Chem. 2014, 53, 7622-7634] but contains a methyl group adjacent to the hydroxo moiety. This α-methylquinoline group in [Mn(III)(OH)(dpaq(2Me))](+) gives rise to a 0.1 Å elongation in the Mn-N(quinoline) distance relative to [Mn(III)(OH)(dpaq(H))](+). Similar bond elongation is observed in the corresponding Mn(II) complex. In MeCN, [Mn(III)(OH)(dpaq(2Me))](+) reacts rapidly with 2,2',6,6'-tetramethylpiperidine-1-ol (TEMPOH) at -35 °C by a concerted proton-electron transfer (CPET) mechanism (second-order rate constant k2 of 3.9(3) M(-1) s(-1)). Using enthalpies and entropies of activation from variable-temperature studies of TEMPOH oxidation by [Mn(III)(OH)(dpaq(2Me))](+) (ΔH(‡) = 5.7(3) kcal(-1) M(-1); ΔS(‡) = -41(1) cal M(-1) K(-1)), it was determined that [Mn(III)(OH)(dpaq(2Me))](+) oxidizes TEMPOH ∼240 times faster than [Mn(III)(OH)(dpaq(H))](+). The [Mn(III)(OH)(dpaq(2Me))](+) complex is also capable of oxidizing the stronger O-H and C-H bonds of 2,4,6-tri-tert-butylphenol and xanthene, respectively. However, for these reactions [Mn(III)(OH)(dpaq(2Me))](+) displays, at best, modest rate enhancement relative to [Mn(III)(OH)(dpaq(H))](+). A combination of density function theory (DFT) and cyclic voltammetry studies establish an increase in the Mn(III)/Mn(II) reduction potential of [Mn(III)(OH)(dpaq(2Me))](+) relative to [Mn(III)(OH)(dpaq(H))](+), which gives rise to a larger driving force for CPET for the former complex. Thus, more favorable thermodynamics for [Mn(III)(OH)(dpaq(2Me))](+) can account for the dramatic increase in rate with TEMPOH. For the more sterically encumbered substrates, DFT computations suggest that this effect is mitigated by unfavorable steric interactions between the

  8. The impact of electronic healthcare associated infection surveillance software on infection prevention resources: A systematic review of the literature.

    PubMed

    Russo, Philip L; Shaban, Ramon Z; MacBeth, Deborough; Carter, Abigail; Mitchell, Brett G

    2017-09-08

    Surveillance of healthcare-associated infections is fundamental for infection prevention. The methods and practices for surveillance have evolved as technology becomes more advanced. The availability of electronic surveillance software (ESS) has increased, and yet adoption of ESS is slow. It is argued that ESS deliver savings through automation, particularly in terms of human resourcing and infection prevention (IP) staff time. This paper describes the findings of a systematic review on the impact of ESS on IP resources. A systematic search was conducted of electronic databases Medline and the Cumulative Index to Nursing and Allied Health Literature published between 1st January 2006 and 31(st) December 2016 with analysis using Newcastle-Ottawa Scale. 2832 articles were reviewed of which 16 studies met the inclusion criteria. IP resources were identified as time undertaken on surveillance. A reduction in IP staff time to undertake surveillance was demonstrated in 13 studies. The reduction proportion ranged from 12.5% - 98.4% (mean 73.9%). The remaining three did not allow for any estimation of the effect in terms of IP staff time. None of the studies demonstrated an increase in IP staff time. The results of this review demonstrate that adopting ESS yield considerable dividends in IP staff time relating to data collection and case ascertainment whilst maintaining high levels of sensitivity and specificity. This has the potential to enable reinvestment into other components of IP to maximise efficient use of scare IP resources. Copyright © 2017. Published by Elsevier Ltd.

  9. Tracking the Flow of Resources in Electronic Waste - The Case of End-of-Life Computer Hard Disk Drives.

    PubMed

    Habib, Komal; Parajuly, Keshav; Wenzel, Henrik

    2015-10-20

    Recovery of resources, in particular, metals, from waste flows is widely seen as a prioritized option to reduce their potential supply constraints in the future. The current waste electrical and electronic equipment (WEEE) treatment system is more focused on bulk metals, where the recycling rate of specialty metals, such as rare earths, is negligible compared to their increasing use in modern products, such as electronics. This study investigates the challenges in recovering these resources in the existing WEEE treatment system. It is illustrated by following the material flows of resources in a conventional WEEE treatment plant in Denmark. Computer hard disk drives (HDDs) containing neodymium-iron-boron (NdFeB) magnets were selected as the case product for this experiment. The resulting output fractions were tracked until their final treatment in order to estimate the recovery potential of rare earth elements (REEs) and other resources contained in HDDs. The results further show that out of the 244 kg of HDDs treated, 212 kg comprising mainly of aluminum and steel can be finally recovered from the metallurgic process. The results further demonstrate the complete loss of REEs in the existing shredding-based WEEE treatment processes. Dismantling and separate processing of NdFeB magnets from their end-use products can be a more preferred option over shredding. However, it remains a technological and logistic challenge for the existing system.

  10. Electron microscopy visualization of DNA-protein complexes formed by Ku and DNA ligase IV.

    PubMed

    Grob, Patricia; Zhang, Teri T; Hannah, Ryan; Yang, Hui; Hefferin, Melissa L; Tomkinson, Alan E; Nogales, Eva

    2012-01-02

    The repair of DNA double-stranded breaks (DSBs) is essential for cell viability and genome stability. Aberrant repair of DSBs has been linked with cancer predisposition and aging. During the repair of DSBs by non-homologous end joining (NHEJ), DNA ends are brought together, processed and then joined. In eukaryotes, this repair pathway is initiated by the binding of the ring-shaped Ku heterodimer and completed by DNA ligase IV. The DNA ligase IV complex, DNA ligase IV/XRRC4 in humans and Dnl4/Lif1 in yeast, is recruited to DNA ends in vitro and in vivo by an interaction with Ku and, in yeast, Dnl4/Lif1 stabilizes the binding of yKu to in vivo DSBs. Here we have analyzed the interactions of these functionally conserved eukaryotic NHEJ factors with DNA by electron microscopy. As expected, the ring-shaped Ku complex bound stably and specifically to DNA ends at physiological salt concentrations. At a ratio of 1 Ku molecule per DNA end, the majority of DNA ends were occupied by a single Ku complex with no significant formation of linear DNA multimers or circular loops. Both Dnl4/Lif1 and DNA ligase IV/XRCC4 formed complexes with Ku-bound DNA ends, resulting in intra- and intermolecular DNA end bridging, even with non-ligatable DNA ends. Together, these studies, which provide the first visualization of the conserved complex formed by Ku and DNA ligase IV at juxtaposed DNA ends by electron microscopy, suggest that the DNA ligase IV complex mediates end-bridging by engaging two Ku-bound DNA ends.

  11. Density functional perturbational orbital theory of spin polarization in electronic systems. II. Transition metal dimer complexes.

    PubMed

    Seo, Dong-Kyun

    2007-11-14

    We present a theoretical scheme for a semiquantitative analysis of electronic structures of magnetic transition metal dimer complexes within spin density functional theory (DFT). Based on the spin polarization perturbational orbital theory [D.-K. Seo, J. Chem. Phys. 125, 154105 (2006)], explicit spin-dependent expressions of the spin orbital energies and coefficients are derived, which allows to understand how spin orbitals form and change their energies and shapes when two magnetic sites are coupled either ferromagnetically or antiferromagnetically. Upon employment of the concept of magnetic orbitals in the active-electron approximation, a general mathematical formula is obtained for the magnetic coupling constant J from the analytical expression for the electronic energy difference between low-spin broken-symmetry and high-spin states. The origin of the potential exchange and kinetic exchange terms based on the one-electron picture is also elucidated. In addition, we provide a general account of the DFT analysis of the magnetic exchange interactions in compounds for which the active-electron approximation is not appropriate.

  12. Electronic structure of Mu-complex donor state in rutile TiO2

    NASA Astrophysics Data System (ADS)

    Shimomura, K.; Kadono, R.; Koda, A.; Nishiyama, K.; Mihara, M.

    2015-08-01

    The hyperfine structure of the interstitial muonium (Mu) in rutile (TiO2, weakly n -type) has been identified by means of a muon-spin-rotation technique. The angle-resolved hyperfine parameters exhibit a tetragonal anisotropy within the a b plane and axial anisotropy with respect to the <001 > (c ̂) axis. This strongly suggests that the Mu is bound to O (forming an OH bond) at an off-center site within a channel along the c ̂ axis, while the unpaired Mu electron is localized around the neighboring Ti site. The hyperfine parameters are quantitatively explained by a model that considers spin polarization of the unpaired electron at both the Ti and O sites, providing evidence for the formation of Mu as a Ti-O-Mu-complex paramagnetic state. The disappearance of the Mu signal above ˜10 K suggests that the energy necessary for the promotion of the unpaired electron to the conduction band by thermal activation is of the order of 101 meV. These observations suggest that, while the electronic structure of Mu (and hence H) differs considerably from that of the conventional shallow level donor described by the effective mass model, Mu supplies a loosely bound electron, and thus, serves as a donor in rutile.

  13. Magnetism and electronic structure of triplet binuclear niobium complexes in inorganic glasses, organic ligand environment, and polymers

    NASA Astrophysics Data System (ADS)

    Rakhimov, R. R.; Arrington, S. A.; Jackson, E. M.; Hwang, J. S.; Prokof'ev, A. I.; Alexandrov, I. A.; Aleksandrov, A. I.

    2005-05-01

    We investigated paramagnetic properties of binuclear niobium complexes Nb-O-Nb with two nonequivalent Nb4+ ions in lithium-niobium phosphate glasses (LNPG), in the environment of catechol/ortho-quinone ligands and in polyethylene. Experimental electron paramagnetic resonance spectrum analysis revealed nonequivalent distribution of the charge and electron spin density between two Nb atoms. Mechanochemical interaction of LNPG with an organic donor-acceptor mixture catechol/ortho-quinone followed by organic solvent extraction leads to the formation of a new binuclear complex with catechol/ortho-quinone ligands. This complex can be further incorporated into polyethylene matrix to form the complex with properties close to the complex in LNPG.

  14. The Nickel-Pincer Complex in Lactate Racemase Is an Electron Relay and Sink that acts through Proton-Coupled Electron Transfer.

    PubMed

    Wang, Binju; Shaik, Sason

    2017-02-03

    QM/MM calculations reveal that the nickel pincer complex in lactate racemase functions as a reversible "single-center electrode" that accepts and donates back an electron. In this way, it catalyzes the isomerization process d-lactate⇌l-lactate through successive proton-coupled electron-transfer steps.

  15. Probing the chemistry, electronic structure and redox energetics in pentavalent organometallic actinide complexes

    SciTech Connect

    Graves, Christopher R; Vaughn, Anthony E; Morris, David E; Kiplinger, Jaqueline L

    2008-01-01

    Complexes of the early actinides (Th-Pu) have gained considerable prominence in organometallic chemistry as they have been shown to undergo chemistries not observed with their transition- or lanthanide metal counterparts. Further, while bonding in f-element complexes has historically been considered to be ionic, the issue of covalence remains a subject of debate in the area of actinide science, and studies aimed at elucidating key bonding interactions with 5f-orbitals continue to garner attention. Towards this end, our interests have focused on the role that metal oxidation state plays in the structure, reactivity and spectral properties of organouranium complexes. We report our progress in the synthesis of substituted U{sup V}-imido complexes using various routes: (1) Direct oxidation of U{sup IV}-imido complexes with copper(I) salts; (2) Salt metathesis with U{sup V}-imido halides; (3) Protonolysis and insertion of an U{sup V}-imido alkyl or aryl complex with H-N{double_bond}CPh{sub 2} or N{triple_bond}C-Ph, respectively, to form a U{sup V}-imido ketimide complex. Further, we report and compare the crystallographic, electrochemical, spectroscopic and magnetic characterization of the pentavalent uranium (C{sub 5}Me{sub 5}){sub 2}U({double_bond}N-Ar)(Y) series (Y = OTf, SPh, C{triple_bond}C-Ph, NPh{sub 2}, OPh, N{double_bond}CPh{sub 2}) to further interrogate the molecular, electronic, and magnetic structures of this new class of uranium complexes.

  16. Electronic and optical response of functionalized Ru(II) complexes: joint theoretical and experimental study

    SciTech Connect

    Kilina, Svetlana; Tretiak, Sergei; Sykora, Milan; Albert, Victor; Badaeva, Ekaterina; Koposov, Alexey

    2008-01-01

    New photovoltaic and photocatalysis applications have been recently proposed based on the hybrid Ru(II)-bipyridine-complex/semiconductor quantum dot systems. In order to attach the Ru(II) complex to the surface of a semiconductor, a linking bridge -- a carboxyl group -- needs to be added to one or two of the 2,2'-bipyridine (bpy) ligands. Such changes in the ligand structure affect electronic and optical properties and, consequently, the charge transfer reactivity of Ru(II)-systems. In this study, we analyze the effects brought by functionalization of bipyridine ligands with the methyl, carboxyl, and carboxilate groups on the electronic structure and optical response of the [Ru(bpy){sub 3}]{sup 2+} complex. First principle calculations based on density functional theory (DFT) and time dependent DFT (TDDFT) are used to simulate the ground and excited-state properties, respectively, of functionalized Ru-complexes in the gas phase and acetonitrile solution. In addition, an effective Frenkel exciton model is used to explain the optical activity and splitting patterns of the low-energy excited states in all molecules. All theoretical results nicely complement and allow for detailed interpretation of experimental absorption spectra of Ru-complexes that have been done in parallel with our theoretical investigations. We found that the carboxyl group breaks the degeneracy of two low-energy optically bright excited states and red-shifts the absorption spectrum, while leaves ionization and affinity energies of complexes almost unchanged. Experimental studies show that deprotonation of the carboxyl group in the Ru-complexes results in a slight blue shift and decrease of oscillator strengths of the low energy absorption peaks. Comparison of experimental and theoretical linear response spectra of deprotonated complexes demonstrate strong agreement if the theoretical calculations are performed with the addition of a dielectric continuum model. A polar solvent is found to play an

  17. The Iron Hill (Powderhorn) Carbonatite Complex, Gunnison County, Colorado - A Potential Source of Several Uncommon Mineral Resources

    USGS Publications Warehouse

    Van Gosen, Bradley S.

    2009-01-01

    A similar version of this slide show was presented on three occasions during 2008: two times to local chapters of the Society for Mining, Metallurgy, and Exploration (SME), as part of SME's Henry Krumb lecture series, and the third time at the Northwest Mining Association's 114th Annual Meeting, held December 1-5, 2008, in Sparks (Reno), Nevada. In 2006, the U.S. Geological Survey (USGS) initiated a study of the diverse and uncommon mineral resources associated with carbonatites and associated alkaline igneous rocks. Most of these deposit types have not been studied by the USGS during the last 25 years, and many of these mineral resources have important applications in modern technology. The author chose to begin this study at Iron Hill in southwestern Colorado because it is the site of a classic carbonatite complex, which is thought to host the largest known resources of titanium and niobium in the United States.

  18. Effect of Access to an Electronic Medical Resource on Performance Characteristics of a Certification Examination: A Randomized Controlled Trial.

    PubMed

    Lipner, Rebecca S; Brossman, Bradley G; Samonte, Kelli M; Durning, Steven J

    2017-09-05

    Electronic resources are increasingly used in medical practice. Their use during high-stakes certification examinations has been advocated by many experts, but whether doing so would affect the capacity to differentiate between high and low abilities is unknown. To determine the effect of electronic resources on examination performance characteristics. Randomized controlled trial. Medical certification program. 825 physicians initially certified by the American Board of Internal Medicine (ABIM) who passed the Internal Medicine Certification examination or sat for the Internal Medicine Maintenance of Certification (IM-MOC) examination in 2012 to 2015. Participants were randomly assigned to 1 of 4 conditions: closed book using typical or additional time, or open book (that is, UpToDate [Wolters Kluwer]) using typical or additional time. All participants took the same modified version of the IM-MOC examination. Primary outcomes included item difficulty (how easy or difficult the question was), item discrimination (how well the question differentiated between high and low abilities), and average question response time. Secondary outcomes included examination dimensionality (that is, the number of factors measured) and test-taking strategy. Item response theory was used to calculate question characteristics. Analysis of variance compared differences among conditions. Closed-book conditions took significantly less time than open-book conditions (mean, 79.2 seconds [95% CI, 78.5 to 79.9 seconds] vs. 110.3 seconds [CI, 109.2 to 111.4 seconds] per question). Mean discrimination was statistically significantly higher for open-book conditions (0.34 [CI, 0.32 to 0.35] vs. 0.39 [CI, 0.37 to 0.41] per question). A strong single dimension showed that the examination measured the same factor with or without the resource. Only 1 electronic resource was evaluated. Inclusion of an electronic resource with time constraints did not adversely affect test performance and did not change

  19. Understanding intention to use electronic information resources: A theoretical extension of the technology acceptance model (TAM).

    PubMed

    Tao, Donghua

    2008-11-06

    This study extended the Technology Acceptance Model (TAM) by examining the roles of two aspects of e-resource characteristics, namely, information quality and system quality, in predicting public health students' intention to use e-resources for completing research paper assignments. Both focus groups and a questionnaire were used to collect data. Descriptive analysis, data screening, and Structural Equation Modeling (SEM) techniques were used for data analysis. The study found that perceived usefulness played a major role in determining students' intention to use e-resources. Perceived usefulness and perceived ease of use fully mediated the impact that information quality and system quality had on behavior intention. The research model enriches the existing technology acceptance literature by extending TAM. Representing two aspects of e-resource characteristics provides greater explanatory information for diagnosing problems of system design, development, and implementation.

  20. Synthesis and electronic structure determination of uranium(vi) ligand radical complexes.

    PubMed

    Herasymchuk, Khrystyna; Chiang, Linus; Hayes, Cassandra E; Brown, Matthew L; Ovens, Jeffrey S; Patrick, Brian O; Leznoff, Daniel B; Storr, Tim

    2016-08-02

    Pentagonal bipyramidal uranyl (UO2(2+)) complexes of salen ligands, N,N'-bis(3-tert-butyl-(5R)-salicylidene)-1,2-phenylenediamine, in which R = (t)Bu (1a), OMe (1b), and NMe2 (1c), were prepared and the electronic structure of the one-electron oxidized species [1a-c]+ were investigated in solution. The solid-state structures of 1a and 1b were solved by X-ray crystallography, and in the case of 1b an asymmetric UO2(2+) unit was found due to an intermolecular hydrogen bonding interaction. Electrochemical investigation of 1a-c by cyclic voltammetry showed that each complex exhibited at least one quasi-reversible redox process assigned to the oxidation of the phenolate moieties to phenoxyl radicals. The trend in redox potentials matches the electron-donating ability of the para-phenolate substituents. The electron paramagnetic resonance spectra of cations [1a-c]+ exhibited gav values of 1.997, 1.999, and 1.995, respectively, reflecting the ligand radical character of the oxidized forms, and in addition, spin-orbit coupling to the uranium centre. Chemical oxidation as monitored by ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy afforded the one-electron oxidized species. Weak low energy intra-ligand charge transfer (CT) transitions were observed for [1a-c]+ indicating localization of the ligand radical to form a phenolate/phenoxyl radical species. Further analysis using density functional theory (DFT) calculations predicted a localized phenoxyl radical for [1a-c]+ with a small but significant contribution of the phenylenediamine unit to the spin density. Time-dependent DFT (TD-DFT) calculations provided further insight into the nature of the low energy transitions, predicting both phenolate to phenoxyl intervalence charge transfer (IVCT) and phenylenediamine to phenoxyl CT character. Overall, [1a-c]+ are determined to be relatively localized ligand radical complexes, in which localization is enhanced as the electron donating ability of the para

  1. Dinitrosyl-iron complexes with thiol-containing ligands: spatial and electronic structures.

    PubMed

    Vanin, Anatoly F; Sanina, Natalia A; Serezhenkov, Vladimir A; Burbaev, Dosymzhan Sh; Lozinsky, Vladimir I; Aldoshin, Sergey M

    2007-02-01

    Parameters of the EPR signals of monomeric dinitrosyl-iron complexes with 1H-1,2,4-triazole-3-thiol (DNIC-MT), obtained by treating MT+ferrous iron in DMSO solution with gaseous NO, have been compared with those of the crystalline monomeric DNIC-MT with tetrahedral structure. Dissolved DNIC-MT were characterized by the isotropic EPR signal centered at g=2.03 with half-width of 0.7 mT and quintet hyperfine structure when recorded at ambient temperature or the anisotropic EPR signal with g( perpendicular)=2.045, g( parallel)=2.014 from frozen solution at 77 kappa, Cyrillic. DNIC-MT in crystalline state showed the structure-less symmetrical singlet EPR signal centered at g=2.03 and half-width of 1.7 mT at both room and liquid nitrogen temperature. The Lorentz shape of this signal indicates the strong exchange interaction between these complexes in the DNIC-MT crystal. Being dissolved in DMSO the crystalline sample of DNIC-MT demonstrated the EPR signal typical for DNIC-MT, obtained by treating MT+ferrous iron in DMSO solution with gaseous NO. Low spin (S=1/2) d(9) electron configuration of DNIC-MT with tetrahedral structure (formula [(MT-S(.))(2)Fe(-1)(NO(+))(2)](+)) was suggested to be responsible for the signal of DNIC-MT in crystalline state. Dissolving of the crystals of DNIC-MT may result in the change of their spatial and electronic structure, namely, tetrahedral structure of the complexes characterized by low spin d(9) electronic configuration transforms into a plane-square structure with d(7) electronic configuration and low spin S=1/2 state (formula [(MT- S(-))(2)Fe(+)(NO(+))(2)](+)). The latter was suggested to be characteristic of other DNICs with various thiol-containing ligands in the solutions. The proposed mechanism of these DNICs formation from ferrous iron, thiol and NO shows that the process could be accompanied by the ionization of NO molecules to NO(+) and NO(-) ions in the complexes. Detailed analysis of the shape of the EPR signals of these

  2. The ETHANOL-CO_2 Dimer is AN Electron Donor-Acceptor Complex

    NASA Astrophysics Data System (ADS)

    McGuire, Brett A.; Martin-Drumel, Marie-Aline; McCarthy, Michael C.

    2017-06-01

    Supercritical (sc) CO_2 is a common industrial solvent for the extraction of caffeine, nicotine, petrochemicals, and natural products. The ability of apolar scCO_2 to dissolve polar solutes is greatly enhanced by the addition of a polar co-solvent, often methanol or ethanol. Experimental and theoretical work show that methanol interactions in scCO_2 are predominantly hydrogen bonding, while the gas-phase complex is an electron donor-acceptor (EDA) configuration. Ethanol, meanwhile, is predicted to form EDA complexes both in scCO_2 and in the gas phase, but there have been no experimental measurements to support this conclusion. Here, we report a combined chirped-pulse and cavity FTMW study of the ethanol-CO_2 complex. Comparison with theory indicates the EDA complex is dominant under our experimental conditions. We confirm the structure with isotopic substitution, and derive a semi-experimental equilibrium structure. Our results are consistent with theoretical predictions that the linearity of the CO_2 subgroup is broken by the complexation interaction.

  3. Synthesis and binding properties of arylethyne-linked porphyrin-zinc complexes for organic electronics applications.

    PubMed

    Reainthippayasakul, W; Paosawatyanyong, B; Bhanthumnavin, W

    2013-05-01

    Conjugated meso-alkynyl 5,15-dimesitylporphyrin metal complexes have been synthesized by Sonogashira coupling reaction in good yields. Alkynyl groups were chosen as a link at the meso positions in order to extend the pi-conjugated length of porphyrin rings. These synthesized porphyrin derivatives were characterized by 1H NMR spectroscopy and MALDI-TOF mass spectrometry. Moreover, UV-visible spectroscopy and fluorescence spectroscopy were also used to investigate their photophysical properties. It has been demonstrated that central metal ions as well as meso substituents on porphyrin rings affected the electronic absorption and emission spectra of the compounds. Spectroscopic results revealed that alkyne-linked porphyrin metal complexes showed higher pi-conjugation compared with porphyrin building blocks resulting in red shifts in both absorption and emission spectra. Coordination properties of synthesized porphyrins were preliminarily investigated by UV-visible absorption and fluorescence emission spectroscopic titration with pyridine as axial ligand. The formation of porphyrin-pyridine complexes resulted in significant red shifts in absorption spectra and decrease of fluorescence intensity in emission spectra. Moreover, the 1H NMR titration experiments suggested that central metal ions play an important role to coordinate with pyridine and the coordination of porphyrin zinc(II) complex with pyridine occur in a 1:1 ratio. From these spectroscopic results, alkyne-linked porphyrin metal complexes offer potential applications as materials for optical organic nanosensors.

  4. Size and structure of antigen-antibody complexes. Electron microscopy and light scattering studies.

    PubMed Central

    Murphy, R M; Slayter, H; Schurtenberger, P; Chamberlin, R A; Colton, C K; Yarmush, M L

    1988-01-01

    Size parameters of model antigen-antibody (Ag-Ab) complexes formed by the interaction of bovine serum albumin (BSA) and pairs of monoclonal anti-BSA antibodies (mAb) were evaluated by quasielastic light scattering, classical light scattering, and electron microscopy (EM). Mean values for the hydrodynamic radius, radius of gyration, and molecular weight were determined by light scattering. Detailed information regarding the molecular weight distribution and the presence of cycles or open chains was obtained with EM. Average molecular weights were calculated from the EM data, and the Porod-Kratky wormlike chain theory was used to model the conformational behavior of the Ag-mAb complexes. Ag-mAb complexes prepared from three different mAb pairs displayed significantly different properties as assessed by each of the techniques employed. Observations and size parameter calculations from EM photomicrographs were consistent with the results from light scattering. The differences observed between the mab pairs would not have been predicted by idealized thermodynamic models. These results suggest that the geometric constraints imposed by the individual epitope environment and/or the relative epitope location are important in determining the average size of complexes and the ratio of linear to cyclic complexes. Images FIGURE 3 FIGURE 3 FIGURE 5 FIGURE 7 PMID:3416033

  5. Building and Managing Electronic Resources in Digital Era in India with Special Reference to IUCAA and NIV, Pune: A Comparative Case Study

    NASA Astrophysics Data System (ADS)

    Sahu, H. K.; Singh, S. N.

    2015-04-01

    This paper discusses and presents a comparative case study of two libraries in Pune, India, Inter-University Centre for Astronomy and Astrophysics and Information Centre and Library of National Institute of Virology (Indian Council of Medical Research). It compares how both libraries have managed their e-resource collections, including acquisitions, subscriptions, and consortia arrangements, while also developing a collection of their own resources, including pre-prints and publications, video lectures, and other materials in an institutional repository. This study illustrates how difficult it is to manage electronic resources in a developing country like India, even though electronic resources are used more than print resources. Electronic resource management can be daunting, but with a systematic approach, various problems can be solved, and use of the materials will be enhanced.

  6. Chlorophyll ring deformation modulates Qy electronic energy in chlorophyll-protein complexes and generates spectral forms.

    PubMed

    Zucchelli, Giuseppe; Brogioli, Doriano; Casazza, Anna Paola; Garlaschi, Flavio M; Jennings, Robert C

    2007-09-15

    The possibility that the chlorophyll (chl) ring distortions observed in the crystal structures of chl-protein complexes are involved in the transition energy modulation, giving rise to the spectral forms, is investigated. The out-of-plane chl-macrocycle distortions are described using an orthonormal set of deformations, defined by the displacements along the six lowest-frequency, out-of-plane normal coordinates. The total chl-ring deformation is the linear combination of these six deformations. The two higher occupied and the two lower unoccupied chl molecular orbitals, which define the Q(y) electronic transition, have the same symmetry as four of the six out-of-plane lowest frequency modes. We assume that a deformation along the normal-coordinate having the same symmetry as a given molecular orbital will perturb that orbital and modify its energy. The changes in the chl Q(y) transition energies are evaluated in the Peridinin-Chl-Protein complex and in light harvesting complex II (LHCII), using crystallographic data. The macrocycle deformations induce a distribution of the chl Q(y) electronic energy transitions which, for LHCII, is broader for chla than for chlb. This provides the physical mechanism to explain the long-held view that the chla spectral forms in LHCII are both more numerous and cover a wider energy range than those of chlb.

  7. The Alternative complex III: properties and possible mechanisms for electron transfer and energy conservation.

    PubMed

    Refojo, Patrícia N; Teixeira, Miguel; Pereira, Manuela M

    2012-10-01

    Alternative complexes III (ACIII) are recently identified membrane-bound enzymes that replace functionally the cytochrome bc(1/)b(6)f complexes. In general, ACIII are composed of four transmembrane proteins and three peripheral subunits that contain iron-sulfur centers and C-type hemes. ACIII are built by a combination of modules present in different enzyme families, namely the complex iron-sulfur molybdenum containing enzymes. In this article a historical perspective on the investigation of ACIII is presented, followed by an overview of the present knowledge on these enzymes. Electron transfer pathways within the protein are discussed taking into account possible different locations (cytoplasmatic or periplasmatic) of the iron-sulfur containing protein and their contribution to energy conservation. In this way several hypotheses for energy conservation modes are raised including linear and bifurcating electron transfer pathways. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012). Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Cu(II) complexes in bacterial growth medium: electron spin resonance study

    NASA Astrophysics Data System (ADS)

    Jung, Katinka; Ristori, Sandra; Martini, Giacomo

    2000-02-01

    In this study we report a spectroscopic investigation on the structure and stability of Cu(II)-complexes that are formed in a minimum growth medium (MM), normally used for Bacillus subtilis cultures. As other transition metals, Cu(II) compounds are toxic to this bacterium and the toxicity depends on the Cu(II) concentration. MM contained NH 4+ ions and asparagine (asn) as the source of inorganic and organic nitrogen. Both ESR and electronic spectra demonstrated the very important role played by the amino acid asparagine in the coordinative behaviour of Cu(II). In particular, three different complexes were evidenced: Cu(H 2O) 62+; Cu(asn) + and Cu(asn) 2. The relative amount of these three species strongly depended on pH, on Cu:asn ratio and on the presence of the phosphate ions. They were identified and evaluated quantitatively by extensive simulation of the electron spin resonance (ESR) spectra recorded in different experimental conditions. The bis-complex was found to be more stable in MM than in an asparagine-containing water solution with the same Cu:asn ratio. A comparison of the spectroscopic results with microbiological investigations is also made.

  9. Print and Electronic Resources: Usage Statistics at Guru Gobind Singh Indraprastha University Library

    ERIC Educational Resources Information Center

    Kapoor, Kanta

    2010-01-01

    Purpose: The purpose of this paper is to quantify the use of electronic journals in comparison with the print collections in the Guru Gobind Singh Indraprastha University Library. Design/methodology/approach: A detailed analysis was made of the use of lending services, the Xerox facility and usage of electronic journals such as Science Direct,…

  10. Print and Electronic Resources: Usage Statistics at Guru Gobind Singh Indraprastha University Library

    ERIC Educational Resources Information Center

    Kapoor, Kanta

    2010-01-01

    Purpose: The purpose of this paper is to quantify the use of electronic journals in comparison with the print collections in the Guru Gobind Singh Indraprastha University Library. Design/methodology/approach: A detailed analysis was made of the use of lending services, the Xerox facility and usage of electronic journals such as Science Direct,…

  11. Electronic Structure and Reactivity of a Well-Defined Mononuclear Complex of Ti(II).

    PubMed

    Wijeratne, Gayan B; Zolnhofer, Eva M; Fortier, Skye; Grant, Lauren N; Carroll, Patrick J; Chen, Chun-Hsing; Meyer, Karsten; Krzystek, J; Ozarowski, Andrew; Jackson, Timothy A; Mindiola, Daniel J; Telser, Joshua

    2015-11-02

    A facile and high-yielding protocol to the known Ti(II) complex trans-[(py)4TiCl2] (py = pyridine) has been developed. Its electronic structure has been probed experimentally using magnetic susceptibility, magnetic circular dichroism, and high-frequency and high-field electron paramagnetic resonance spectroscopies in conjunction with ligand-field theory and computational methods (density functional theory and ab initio methods). These studies demonstrated that trans-[(py)4TiCl2] has a (3)Eg ground state (dxy(1)dxz,yz(1) orbital occupancy), which, as a result of spin–orbit coupling, yields a ground-state spinor doublet that is EPR active, a first excited-state doublet at ∼60 cm(–1), and two next excited states at ∼120 cm(–1). Reactivity studies with various unsaturated substrates are also presented in this study, which show that the Ti(II) center allows oxidative addition likely via formation of [Ti(η(2)-R2E2)Cl2(py)n] E = C, N intermediates. A new Ti(IV) compound, mer-[(py)3(η(2)-Ph2C2)TiCl2], was prepared by reaction with Ph2C2, along with the previously reported complex trans-(py)3Ti═NPh(Cl)2, from reaction with Ph2N2. Reaction with Ph2CN2 also yielded a new dinuclear Ti(IV) complex, [(py)2(Cl)2Ti(μ2:η(2)-N2CPh2)2Ti(Cl)2], in which the two Ti(IV) ions are inequivalently coordinated. Reaction with cyclooctatetraene (COT) yielded a new Ti(III) complex, [(py)2Ti(η(8)-COT)Cl], which is a rare example of a mononuclear “piano-stool” titanium complex. The complex trans-[(py)4TiCl2] has thus been shown to be synthetically accessible, have an interesting electronic structure, and be reactive toward oxidation chemistry.

  12. Theoretical Studies on the Electronic Structures and Properties of Complex Ceramic Crystals and Novel Materials

    SciTech Connect

    Ching, Wai-Yim

    2012-01-14

    This project is a continuation of a long program supported by the Office of Basic Energy Science in the Office of Science of DOE for many years. The final three-year continuation started on November 1, 2005 with additional 1 year extension to October 30, 2009. The project was then granted a two-year No Cost Extension which officially ended on October 30, 2011. This report covers the activities within this six year period with emphasis on the work completed within the last 3 years. A total of 44 papers with acknowledgement to this grant were published or submitted. The overall objectives of this project are as follows. These objectives have been evolved over the six year period: (1) To use the state-of-the-art computational methods to investigate the electronic structures of complex ceramics and other novel crystals. (2) To further investigate the defects, surfaces/interfaces and microstructures in complex materials using large scale modeling. (3) To extend the study on ceramic materials to more complex bioceramic crystals. (4) To initiate the study on soft condensed matters including water and biomolecules. (5) To focus on the spectroscopic studies of different materials especially on the ELNES and XANES spectral calculations and their applications related to experimental techniques. (6) To develop and refine computational methods to be effectively executed on DOE supercomputers. (7) To evaluate mechanical properties of different crystals and those containing defects and relate them to the fundamental electronic structures. (8) To promote and publicize the first-principles OLCAO method developed by the PI (under DOE support for many years) for applications to large complex material systems. (9) To train a new generation of graduate students and postdoctoral fellows in modern computational materials science and condensed matter physics. (10) To establish effective international and domestic collaborations with both experimentalists and theorists in materials

  13. Controlling the two-dimensional electron gas at complex oxide interfaces

    NASA Astrophysics Data System (ADS)

    Janotti, Anderson

    2014-03-01

    Heterostructures of complex oxides have attracted great interest since the demonstration of a high-density two-dimensional electron gas (2DEG) at the SrTiO3/LaAlO3 (STO/LAO) interface. Still, the density of the 2DEG is only one tenth of what was expected from simple electron counting, i.e., 1/2 electron per unit-cell area. Since then, the origin and amount of the charge, the electrical properties of the 2DEG, the role of native defects, and the abrupt variation of the electron density with the thickness of the LAO top layer have been the subject of numerous theoretical and experimental studies. More recently, a 2DEG with the full density of 1/2 electron per unit cell area has been observed at the interface between the band insulator STO and the Mott insulator GdTiO3 (GTO), shedding additional light on the origin of the 2DEG, and raising important questions on the differences between the STO/LAO and STO/GTO heterostructures. Here we will discuss the similarities of the 2DEG at the STO/LAO and STO/GTO heterostructures from the perspective of first-principles simulations. We will address the differences in band alignments in the STO/LAO and STO/GTO heterostructures, and how the 2DEG is affected by the surface of the LAO top layer in the STO/LAO, but apparently not in the STO/GTO case. Finally, we will also discuss how heterostructures can be used to drastically alter the electronic structure of STO, transforming it from a band insulator into a Mott insulator. This work was performed in collaboration with Lars Bjaalie, Luke Gordon, Burak Himmetoglu, and Chris G. Van de Walle, and supported by ARO and NSF.

  14. Direct observation of a bent carbonyl ligand in a 19-electron transition metal complex.

    PubMed

    Lomont, Justin P; Nguyen, Son C; Harris, Charles B

    2013-03-21

    The photochemistry of [CpRu(CO)2]2 in P(OMe)3/CH2Cl2 solution has been studied using picosecond time-resolved infrared (TRIR) spectroscopy. Photolysis at 400 nm leads to the formation of 17-electron CpRu(CO)2(•) radicals, which react on the picosecond time scale to form 19-electron CpRu(CO)2P(OMe)3(•) adducts. The TRIR spectra of this adduct display an unusually low CO stretching frequency for the antisymmetric CO stretching mode, suggesting that one carbonyl ligand adopts a bent configuration to avoid a 19-electron count at the metal center. This spectral assignment is supported by analogous experiments on [CpFe(CO)2]2 in the same solvent, combined with DFT studies on the structures of the 19-electron adducts. The DFT results predict a bent CO ligand in CpRu(CO)2P(OMe)3(•), whereas approximately linear Fe-C-O bond angles are predicted for CpFe(CO)2P(OMe)3(•). The observation of a bent CO ligand in the 19-electron ruthenium adduct is a surprising result, and it provides new insight into the solution-phase behavior of 19-electron complexes. TRIR spectra were also collected for [CpRu(CO)2]2 in neat CH2Cl2, and it is interesting to note that no singly bridged [CpRu(CO)]2(μ-CO) photoproduct was observed to form following 400- or 267-nm excitation, despite previous observations of this species on longer time scales.

  15. Dimethylamine borane dehydrogenation chemistry: syntheses, X-ray and neutron diffraction studies of 18-electron aminoborane and 14-electron aminoboryl complexes.

    PubMed

    Tang, Christina Y; Phillips, Nicholas; Bates, Joshua I; Thompson, Amber L; Gutmann, Matthias J; Aldridge, Simon

    2012-08-21

    The reactions of Me(2)NH·BH(3) with cationic Rh(III) and Ir(III) complexes have been shown to generate the 18-electron aminoborane adduct [Ir(IMes)(2)(H)(2){κ(2)-H(2)BNMe(2))](+) and the remarkable 14-electron aminoboryl complex [Rh(IMes)(2)(H)-{B(H)NMe(2))](+). Neutron diffraction studies have been used for the first time to define H-atom locations in metal complexes of this type formed under catalytic conditions.

  16. Liquid scanning transmission electron microscopy: imaging protein complexes in their native environment in whole eukaryotic cells.

    PubMed

    Peckys, Diana B; de Jonge, Niels

    2014-04-01

    Scanning transmission electron microscopy (STEM) of specimens in liquid, so-called Liquid STEM, is capable of imaging the individual subunits of macromolecular complexes in whole eukaryotic cells in liquid. This paper discusses this new microscopy modality within the context of state-of-the-art microscopy of cells. The principle of operation and equations for the resolution are described. The obtained images are different from those acquired with standard transmission electron microscopy showing the cellular ultrastructure. Instead, contrast is obtained on specific labels. Images can be recorded in two ways, either via STEM at 200 keV electron beam energy using a microfluidic chamber enclosing the cells, or via environmental scanning electron microscopy at 30 keV of cells in a wet environment. The first series of experiments involved the epidermal growth factor receptor labeled with gold nanoparticles. The labels were imaged in whole fixed cells with nanometer resolution. Since the cells can be kept alive in the microfluidic chamber, it is also feasible to detect the labels in unfixed, live cells. The rapid sample preparation and imaging allows studies of multiple whole cells.

  17. Electron transfer reactions in the alkene mono-oxygenase complex from Nocardia corallina B-276.

    PubMed Central

    Gallagher, S C; Cammack, R; Dalton, H

    1999-01-01

    Nocardia corallina B-276 possesses a multi-component enzyme, alkene mono-oxygenase (AMO), that catalyses the stereoselective epoxygenation of alkenes. The reductase component of this system has been shown by EPR and fluorescence spectroscopy to contain two prosthetic groups, an FAD centre and a [2Fe-2S] cluster. The role of these centres in the epoxygenation reaction was determined by midpoint potential measurements and electron transfer kinetics. The order of potentials of the prosthetic groups of the reductase were FAD/FAD.=-216 mV, [2Fe-2S]/[2Fe-2S].=-160 mV and FAD./FAD.=-134 mV. Combined, these data implied that the reductase component supplied the energy required for the epoxygenation reaction and allowed a prediction of the mechanism of electron transfer within the AMO complex. The FAD moiety was reduced by bound NADH in a two-electron reaction. The electrons were then transported to the [2Fe-2S] centre one at a time, which in turn reduced the di-iron centre of the epoxygenase. Reduction of the di-iron centre is required for oxygen binding and substrate oxidation. PMID:10085230

  18. Traceability and Risk Analysis Strategies for Addressing Counterfeit Electronics in Supply Chains for Complex Systems.

    PubMed

    DiMase, Daniel; Collier, Zachary A; Carlson, Jinae; Gray, Robin B; Linkov, Igor

    2016-10-01

    Within the microelectronics industry, there is a growing concern regarding the introduction of counterfeit electronic parts into the supply chain. Even though this problem is widespread, there have been limited attempts to implement risk-based approaches for testing and supply chain management. Supply chain risk management tends to focus on the highly visible disruptions of the supply chain instead of the covert entrance of counterfeits; thus counterfeit risk is difficult to mitigate. This article provides an overview of the complexities of the electronics supply chain, and highlights some gaps in risk assessment practices. In particular, this article calls for enhanced traceability capabilities to track and trace parts at risk through various stages of the supply chain. Placing the focus on risk-informed decision making through the following strategies is needed, including prioritization of high-risk parts, moving beyond certificates of conformance, incentivizing best supply chain management practices, adoption of industry standards, and design and management for supply chain resilience.

  19. Electronic states of alkali metal-NTCDA complexes: A DFT study

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto; Kawabata, Hiroshi

    2015-10-01

    Structures and electronic states of organic-inorganic compound of 1,4,5,8-naphthalene-tetracarboxylic-dianhydride (NTCDA) with alkali metals, Mn(NTCDA) (Mdbnd Li and Na, n = 0-2), have been investigated by means of hybrid density functional theory (DFT) calculations. From the DFT calculations, it was found that the electronic state of the complex at the ground state is characterized by a charge-transfer state expressed by (M)+(NTCDA)-. The alkali metals were bound equivalently to the carbonyl oxygen and ether oxygen atoms of NTCDA. The Cdbnd O double bond character of NTCDA was changed to a C-O single bond like character by the strong interaction of M to the Cdbnd O and O sites. This change was the origin of the red-shift of the IR spectrum. The UV-vis absorption spectra of Mn(NTCDA) were theoretically predicted on the basis of theoretical results.

  20. Density functional calculation of core-electron binding energies of transition metal carbonyl and nitrosyl complexes

    NASA Astrophysics Data System (ADS)

    Hu, Ching-Han; Chong, Delano P.

    1996-11-01

    Our recent procedure of the unrestricted generalized transition state (uGTS) model for density functional calculations of core-electron binding energies has been applied to seven carbonyl and nitrosyl inorganic complexes: Fe(CO) 5, Ni(CO) 4, Mn(CO) 4NO, Co(CO) 3NO, Fe(CO) 2(NO) 2, Mn(NO) 3CO and Cr(NO) 4. The exchange-correlation potential is based on a combined functional of Becke's exchange (B88) and Perdew's correlation (P86). The cc-pVTZ basis set was used for the calculation of neutral molecules, while for the partial cation created in the uGTS approach we scaled the cc-pVTZ basis set using a procedure based on Clementi and Raimondi's rules for atomic screening. The average absolute deviation of the calculated core-electron binding energy from experiment is 0.28 eV.

  1. Electron-Transfer Pathways in the Heme and Quinone-Binding Domain of Complex II (Succinate Dehydrogenase)

    PubMed Central

    2015-01-01

    Single electron transfers have been examined in complex II (succinate:ubiquinone oxidoreductase) by the method of pulse radiolysis. Electrons are introduced into the enzyme initially at the [3Fe–4S] and ubiquinone sites followed by intramolecular equilibration with the b heme of the enzyme. To define thermodynamic and other controlling parameters for the pathways of electron transfer in complex II, site-directed variants were constructed and analyzed. Variants at SdhB-His207 and SdhB-Ile209 exhibit significantly perturbed electron transfer between the [3Fe–4S] cluster and ubiquinone. Analysis of the data using Marcus theory shows that the electronic coupling constants for wild-type and variant enzyme are all small, indicating that electron transfer occurs by diabatic tunneling. The presence of the ubiquinone is necessary for efficient electron transfer to the heme, which only slowly equilibrates with the [3Fe–4S] cluster in the absence of the quinone. PMID:24559074

  2. Electronic and vibronic properties of a discotic liquid-crystal and its charge transfer complex.

    PubMed

    Haverkate, Lucas A; Zbiri, Mohamed; Johnson, Mark R; Carter, Elizabeth; Kotlewski, Arek; Picken, S; Mulder, Fokko M; Kearley, Gordon J

    2014-01-07

    Discotic liquid crystalline (DLC) charge transfer (CT) complexes combine visible light absorption and rapid charge transfer characteristics, being favorable properties for photovoltaic (PV) applications. We present a detailed study of the electronic and vibrational properties of the prototypic 1:1 mixture of discotic 2,3,6,7,10,11-hexakishexyloxytriphenylene (HAT6) and 2,4,7-trinitro-9-fluorenone (TNF). It is shown that intermolecular charge transfer occurs in the ground state of the complex: a charge delocalization of about 10(-2) electron from the HAT6 core to TNF is deduced from both Raman and our previous NMR measurements [L. A. Haverkate, M. Zbiri, M. R. Johnson, B. Deme, H. J. M. de Groot, F. Lefeber, A. Kotlewski, S. J. Picken, F. M. Mulder, and G. J. Kearley, J. Phys. Chem. B 116, 13098 (2012)], implying the presence of permanent dipoles at the donor-acceptor interface. A combined analysis of density functional theory calculations, resonant Raman and UV-VIS absorption measurements indicate that fast relaxation occurs in the UV region due to intramolecular vibronic coupling of HAT6 quinoidal modes with lower lying electronic states. Relatively slower relaxation in the visible region the excited CT-band of the complex is also indicated, which likely involves motions of the TNF nitro groups. The fast quinoidal relaxation process in the hot UV band of HAT6 relates to pseudo-Jahn-Teller interactions in a single benzene unit, suggesting that the underlying vibronic coupling mechanism can be generic for polyaromatic hydrocarbons. Both the presence of ground state CT dipoles and relatively slow relaxation processes in the excited CT band can be relevant concerning the design of DLC based organic PV systems.

  3. Bonding and Electronic Properties of Linear Diethynyl Oligothienoacene-Bridged Diruthenium Complexes and Their Oxidized Forms.

    PubMed

    Ou, Ya-Ping; Zhang, Jing; Zhang, Ming-Xing; Zhang, Fuxing; Kuang, Daizhi; Hartl, František; Liu, Sheng Hua

    2017-08-29

    A series of five diruthenium diethynyl complexes based on α,β-fused oligothienoacenes in the core of the bridging ligands [{Ru(dppe)Cp*}2(μ-C≡C-L-C≡C)] [dppe = 1,2-bis(diphenylphosphino)ethane, Cp* = η(5)-C5Me5; L = thieno[3,2-b]thiophene (4), thieno[2,3-b]thiophene (5), 3,4-dimethylthieno[2,3-b]thiophene (6), dithieno[3,2-b:2',3'-d]thiophene (7), and thieno[3,2-b]thieno[2',3':4,5]thieno[2,3-d]thiophene (8)] have been synthesized and fully characterized electrochemically and spectroscopically. Elongation of the redox noninnocent oligothienoacene bridge core causes a smaller potential difference between the initial two anodic steps, not seen for free dialkyl oligothienoacenes, and increased positive charge delocalization over the conjugated bridge backbone. The highest occupied molecular orbital of the parent complexes resides predominantly on the oligothienoacene core, with strong participation of the ethynyl linkers and slightly smaller contribution from the metallic termini. This bonding character makes the initial one-electron oxidation symmetrical, as revealed by combined voltammetric and spectroscopic (IR, UV-vis-near-IR, and electron paramagnetic resonance) methods as well as density functional theory (DFT) and time-dependent DFT calculations of truncated and selected nontruncated models of the studied series. The remarkable gradual appearance of two C≡C stretching absorptions in the IR spectra of the monocationic diethynyl complexes is ascribed to increasing vibronic coupling of the IR-forbidden νs(C≡C) mode of the oxidized -[C≡C-core-C≡C](+)- bridge with a low-lying π-π*(intrabridge)/metal-to-ligand charge-transfer electronic transition in the near-to-mid-IR spectral region.

  4. Molecular basis of coupled protein and electron transfer dynamics of cytochrome c in biomimetic complexes.

    PubMed

    Alvarez-Paggi, Damián; Martín, Diego F; DeBiase, Pablo M; Hildebrandt, Peter; Martí, Marcelo A; Murgida, Daniel H

    2010-04-28

    Direct electron transfer (ET) of redox proteins immobilized on biomimetic or biocompatible electrodes represents an active field of fundamental and applied research. In this context, several groups have reported for a variety of proteins unexpected distance dependencies of the ET rate, whose origin remains largely speculative and controversial, but appears to be a quite general phenomenon. Here we have employed molecular dynamics (MD) simulations and electron pathway analyses to study the ET properties of cytochrome c (Cyt) electrostatically immobilized on Au coated by carboxyl-terminated alkylthiols. The MD simulations and concomitant binding energy calculations allow identification of preferred binding configurations of the oxidized and reduced Cyt which are established via different lysine residues and, thus, correspond to different orientations and dipole moments. Calculations of the electronic coupling matrices for the various Cyt/self-assembled monolayer (SAM) complexes indicate that the thermodynamically preferred protein orientations do not coincide with the orientations of optimum coupling. These findings demonstrate that the ET of the immobilized Cyt is controlled by an interplay between protein dynamics and tunneling probabilities. Protein dynamics exerts two level of tuning on the electronic coupling via reorientation (coarse) and low amplitude thermal fluctuations (fine). Upon operating the Au support as an electrode, electric-field-dependent alignment of the protein dipole moment becomes an additional determinant for the protein dynamics and thus for the overall ET rate. The present results provide a consistent molecular description of previous (spectro)electrochemical data and allow conclusions concerning the coupling of protein dynamics and ET of Cyt in physiological complexes.

  5. Electron-helium scattering in the S-wave model using exterior complex scaling

    SciTech Connect

    Horner, Daniel A.; McCurdy, C. William; Rescigno, Thomas N.

    2004-06-16

    Electron-impact excitation and ionization of helium is studied in the S-wave model. The problem is treated in full dimensionality using a time-dependent formulation of the exterior complex scaling method that does not involve the solution of large linear systems of equations. We discuss the steps that must be taken to compute stable ionization amplitudes. We present total excitation, total ionization and single differential cross sections from the ground and n=2 excited states and compare our results with those obtained by others using a frozen-core model.

  6. Electron correlation and relative energy characteristics in nonempirical calculations of complex beryllohydrides of light elements

    SciTech Connect

    Charkin, O.P.; Cimiraglia, R.; Persico, M.; Tomasi, J.

    1987-01-01

    Nonempirical ab initio calculations have been carried out for 15 molecules of simple and complex beryllohydrides and their salts in the SCF approximation and with consideration of the electron correlation in the CIPSI, MP3, and CISD approximations with various basis sets from 6-31G to 6-311G**. The importance of the correlation contributions to the relative energy characteristics (the dissociation energies, the relative energies of alternative geometric configurations, etc.) of these molecules has been analyzed. The effectiveness of the additive approach for the description of the correlation contributions has been analyzed in series of closely related compounds.

  7. Complex internal rearrangement processes triggered by electron transfer to acetic acid

    NASA Astrophysics Data System (ADS)

    Limão-Vieira, P.; Meneses, G.; Cunha, T.; Gil, A.; Calhorda, M. J.; García, G.; Ferreira da Silva, F.

    2015-09-01

    We present negative ion formation from collisions of 100 eV neutral potassium atoms with acetic acid (CH3COOH) and its deuterated analogue molecules (CH3COOD, CD3COOH). From the negative ion time-of-flight (TOF) mass spectra, OH- is the main fragment detected accounting on average for more than 25% of the total anion yield. The complex internal rearrangement processes triggered by electron transfer to acetic acid have been evaluated with the help of theoretical calculations at the DFT levels explaining the fragmentation channel yielding OH-.

  8. Peculiarity in the electronic structure of Cu(II) complex ferromagnetically coupled with bisimino nitroxides.

    PubMed

    Ikoma, Tadaaki; Oshio, Hiroki; Yamamoto, Masashi; Ohba, Yasunori; Nihei, Masayuki

    2008-09-18

    By means of the electron spin resonance (ESR) technique, we have investigated the electronic structures of the tridentate imino nitroxyl diradical complex with copper(II) (Cu-bisimpy), which has a square planar structure and a ground quartet state with an extremely strong ferromagnetic exchange interaction, and its related compounds (bisimpy = 2,6-bis(1'-oxyl-4',4',5',5'-tetramethyl-4',5'-dihydro-1' H-imidazol-2'-yl)pyridine). It was clarified that Cu-bisimpy had unique magnetic orbitals, compared with the biradical ligand (bisimpy), a zinc(II) biradical complex (Zn-bisimpy) and a copper(II) terpyridine complex (Cu-tpy) (tpy = 2,2';6',2''-terpyridine). Multifrequency ESR spectroscopy provided a reliable set of magnetic parameters of Cu-bisimpy, which has a small g anisotropy ( g x = 2.02, g y = 2.01, g z = 2.08) and small hyperfine coupling with Cu (|A x| = 42.0 MHz, |A y|electron spin resonance spectroscopy clarified the unique electronic structure of a square planar copper(II) complex with an imino nitroxyl diradical, which undergoes a strong ferromagnetic interaction caused by a covalent bonding effect.

  9. Protein film voltammetry and co-factor electron transfer dynamics in spinach photosystem II core complex.

    PubMed

    Zhang, Yun; Magdaong, Nikki; Frank, Harry A; Rusling, James F

    2014-05-01

    Direct protein film voltammetry (PFV) was used to investigate the redox properties of the photosystem II (PSII) core complex from spinach. The complex was isolated using an improved protocol not used previously for PFV. The PSII core complex had high oxygen-evolving capacity and was incorporated into thin lipid and polyion films. Three well-defined reversible pairs of reduction and oxidation voltammetry peaks were observed at 4 °C in the dark. Results were similar in both types of films, indicating that the environment of the PSII-bound cofactors was not influenced by film type. Based on comparison with various control samples including Mn-depleted PSII, peaks were assigned to chlorophyll a (Chl a) (Em = -0.47 V, all vs. NHE, at pH 6), quinones (-0.12 V), and the manganese (Mn) cluster (Em = 0.18 V). PFV of purified iron heme protein cytochrome b-559 (Cyt b-559), a component of PSII, gave a partly reversible peak pair at 0.004 V that did not have a potential similar to any peaks observed from the intact PSII core complex. The closest peak in PSII to 0.004 V is the 0.18 V peak that was found to be associated with a two-electron process, and thus is inconsistent with iron heme protein voltammetry. The -0.47 V peak had a peak potential and peak potential-pH dependence similar to that found for purified Chl a incorporated into DMPC films. The midpoint potentials reported here may differ to various extents from previously reported redox titration data due to the influence of electrode double-layer effects. Heterogeneous electron transfer (hET) rate constants were estimated by theoretical fitting and digital simulations for the -0.47 and 0.18 V peaks. Data for the Chl a peaks were best fit to a one-electron model, while the peak assigned to the Mn cluster was best fit by a two-electron/one-proton model.

  10. Intention to use and actual use of electronic information resources: further exploring Technology Acceptance Model (TAM).

    PubMed

    Tao, Donghua

    2009-11-14

    Following up a previous study that examined public health students' intention to use e-resources for completing research paper assignments, the present study proposed two models to investigate whether or not public health students actually used the e-resources they intended to use and whether or not the determinants of intention to use predict actual use of e-resources. Focus groups and pre- and post-questionnaires were used to collect data. Descriptive analysis, data screening, and Structural Equation Modeling (SEM) techniques were used for data analysis. The study found that the determinants of intention-to-use significantly predict actual use behavior. Direct impact of perceived usefulness and indirect impact of perceived ease of use to both behavior intention and actual behavior indicated the importance of ease of use at the early stage of technology acceptance. Non-significant intention-behavior relationship prompted thoughts on the measurement of actual behavior and multidimensional characteristics of the intention construct.

  11. Electronic density topology of metal—metal quadruple bond in some Mo complexes

    NASA Astrophysics Data System (ADS)

    Sierraalta, Anibal

    1994-09-01

    The nature of the quadruple metal—metal bond form MMo(O 2CH) 4 (M=Mo, Cr), and Mo 2X 4(PH 3) 4) (X=Cl, Br, I) complexes, was investigated using the Bader theory and relativistic pseudopotentials. The topological results show that the direct metalmetal interaction is dominated by a strong charge depletion at the bond critical point. The identity of the halide ligands in Mo 2X 4(PH 3) 4 complexes does not affect the electronic density of the MoMo bond. This result is in accord with the experimental fact that the MoMo distances in Mo 2X 4(PMe 3) 4 appears to be independent of the halide ligands.

  12. Monitoring Complex Formation by Relaxation-Induced Pulse Electron Paramagnetic Resonance Distance Measurements.

    PubMed

    Giannoulis, Angeliki; Oranges, Maria; Bode, Bela E

    2017-09-06

    Biomolecular complexes are often multimers fueling the demand for methods that allow unraveling their composition and geometric arrangement. Pulse electron paramagnetic resonance (EPR) spectroscopy is increasingly applied for retrieving geometric information on the nanometer scale. The emerging RIDME (relaxation-induced dipolar modulation enhancement) technique offers improved sensitivity in distance experiments involving metal centers (e.g. on metalloproteins or proteins labelled with metal ions). Here, a mixture of a spin labelled ligand with increasing amounts of paramagnetic Cu(II) ions allowed accurate quantification of ligand-metal binding in the model complex formed. The distance measurement was highly accurate and critical aspects for identifying multimerization could be identified. The potential to quantify binding in addition to the high-precision distance measurement will further increase the scope of EPR applications. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  13. [Characteristics of mixed association and deactivation of electron excitation in chlorophyll-pheophytin complexes].

    PubMed

    Zen'kevich, E I; Zen'kevich, T V

    1984-01-01

    The regularities of the individual and mixed association of chlorophylls (Chl a, PChl a) with pheophytin (Pheo) were investigated. The complex studies of optical activity, spectral--luminescent and energetic characteristics of aggregates were carried out in mixture of solvents aceton-water (1:49). The formation of pigment mixed associates leads to intracomplex energy transfer from Chl (or PChl) to Pheo. It is shown that the efficiencies of such process, determined by independent ways via the luminescence quenching of energy donor or the emission sensibilization of acceptor, are identical. The energy migration mechanism is the inductive resonance one in studied complexes. The main patterns of the electronic excitation energy deactivation in such systems are discussed. The obtained results are analysed taking into account the contemporary background of the role of pheophytin in the primary processes of photosynthesis.

  14. Tracking the charge and spin dynamics of electronic excited states in inorganic complexes

    NASA Astrophysics Data System (ADS)

    Gaffney, Kelly

    2015-03-01

    Inorganic complexes have many advantageous properties for solar energy applications, including strong visible absorption and photocatalytic activity. Whether used as a photocatalyst or a photosensitizer, the lifetime of electronic excited states and the earth abundance of the molecular components represent a key property for solar energy applications. These dual needs have undermined the usefulness of many coordination compounds. Isoelectronic iron and ruthenium based complexes represent a clear example. Ru-polypyridal based molecules have been the workhorse of solar energy related research and dye sensitized solar cells for decades, but the replacement of low abundance Ru with Fe leads to million-fold reductions in metal to ligand charge transfer (MLCT) excited state lifetimes. Understanding the origin of this million-fold reduction in lifetime and how to control excited state relaxation in 3d-metal complexes motivates the work I will discuss. We have used the spin sensitivity of hard x-ray fluorescence spectroscopy and the intense femtosecond duration pulses generated by the LCLS x-ray laser to probe the spin dynamics in a series of electronically excited [Fe(CN)6-2N(2,2'-bipyridine)N]2 N - 4 complexes, with N = 1-3. These femtosecond resolution measurements demonstrate that modification of the solvent and ligand environment can lengthen the MLCT excited state lifetime by more than two orders of magnitude. They also verify the role of triplet ligand field excited states in the spin crossover dynamics from singlet to quintet spin configurations. Work supported by the AMOS program within the Chemical Sciences, Geosciences, and Biosciences Division of the Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

  15. Structural Characterization of Native Proteins and Protein Complexes by Electron Ionization Dissociation-Mass Spectrometry.

    PubMed

    Li, Huilin; Sheng, Yuewei; McGee, William; Cammarata, Michael; Holden, Dustin; Loo, Joseph A

    2017-03-07

    Mass spectrometry (MS) has played an increasingly important role in the identification and structural and functional characterization of proteins. In particular, the use of tandem mass spectrometry has afforded one of the most versatile methods to acquire structural information for proteins and protein complexes. The unique nature of electron capture dissociation (ECD) for cleaving protein backbone bonds while preserving noncovalent interactions has made it especially suitable for the study of native protein structures. However, the intra- and intermolecular interactions stabilized by hydrogen bonds and salt bridges can hinder the separation of fragments even with preactivation, which has become particularly problematic for the study of large macromolecular proteins and protein complexes. Here, we describe the capabilities of another activation method, 30 eV electron ionization dissociation (EID), for the top-down MS characterization of native protein-ligand and protein-protein complexes. Rich structural information that cannot be delivered by ECD can be generated by EID. EID allowed for the comparison of the gas-phase and the solution-phase structural stability and unfolding process of human carbonic anhydrase I (HCA-I). In addition, the EID fragmentation patterns reflect the structural similarities and differences among apo-, Zn-, and Cu,Zn-superoxide dismutase (SOD1) dimers. In particular, the structural changes due to Cu-binding and a point mutation (G41D) were revealed by EID-MS. The performance of EID was also compared to that of 193 nm ultraviolet photodissociation (UVPD), which allowed us to explore their qualitative similarities and differences as potential valuable tools for the MS study of native proteins and protein complexes.

  16. Electronic structure of thioether containing NSNO donor azo-ligand and its copper(II) complex: Experimental and theoretical studies

    NASA Astrophysics Data System (ADS)

    Pramanik, Ajoy Kumar; Sarkar, Deblina; Mondal, Tapan Kumar

    2015-11-01

    Synthesis of thioether containing NSNO donor azo ligand (HL) showing hydrazoketo and azoenol tautomerism has been performed. The hydrazoketo and azoenol equilibrium of HL has been studied. The hydrazoketo form of HL is predominating over azoenol form. In copper(II) complex the ligand is present in azoenol form. The electronic spectra and electronic structure of the complex has been extensively studied. The structures of the ligand and copper(II) complex have been established from single crystal X-ray studies. The 1-D supramolecular structure of the complex is formed by π-π interactions.

  17. On the electronic structure of nitro-substituted bipyridines and their platinum complexes.

    PubMed

    Murray, Paul R; Crawford, Stephen; Dawson, Alice; Delf, Alexander; Findlay, Calum; Jack, Lorna; McInnes, Eric J L; Al-Musharafi, Salma; Nichol, Gary S; Oswald, Iain; Yellowlees, Lesley J

    2012-01-07

    We report the preparation and electrochemical studies of a systematic series of mono- and di-nitro-substituted 2,2'-bipyridine (bipy) compounds [x-NO(2)-bipy (x = 3,4) and x,x'-(NO(2))(2)-bipy (x,x' = 3, 4, 5)] and their complexes with platinum(II), [Pt(x-NO(2)-bipy)Cl(2)] and [Pt(x,x'-(NO(2))(2)-bipy)Cl(2)]. The effect of the number and substitution pattern of the nitro groups on the low-lying acceptor molecular orbitals (involved in charge transfer transitions) is probed by in situ UV/Vis/NIR and EPR spectroelectrochemical methods, supported by DFT calculations. The LUMOs of x-NO(2)-bipy (x = 3-5) are largely localised on the NO(2)-pyridyl moiety; this is also true of their {PtCl(2)} complexes but with a small but significant shift of electron density from the nitro groups. The LUMOs of x,x'-(NO(2))(2)-bipy with x = 3 and 5 are delocalised over both NO(2)-pyridyl rings, but for 4,4'-(NO(2))(2)-bipy is localised on a single NO(2)-pyridyl ring. In all cases the LUMO of the [Pt(x,x'-(NO(2))(2)-bipy)Cl(2)] complexes is delocalised over both nitro-pyridyl rings. For all complexes, the 4(4') derivatives allows greatest overlap with metal valence orbitals in the LUMO.

  18. Detection and structural characterization of oxo-chromium(V)-sugar complexes by electron paramagnetic resonance.

    PubMed

    Sala, Luis F; González, Juan C; García, Silvia I; Frascaroli, María I; Van Doorslaer, Sabine

    2011-01-01

    This article describes the detection and characterization of oxo-Cr(V)-saccharide coordination compounds, produced during chromic oxidation of carbohydrates by Cr(VI) and Cr(V), using electron paramagnetic resonance (EPR) spectroscopy. After an introduction into the main importance of chromium (bio)chemistry, and more specifically the oxo-chromium(V)-sugar complexes, a general overview is given of the current state-of-the-art EPR techniques. The next step reviews which types of EPR spectroscopy are currently applied to oxo-Cr(V) complexes, and what information about these systems can be gained from such experiments. The advantages and pitfalls of the different approaches are discussed, and it is shown that the potential of high-field and pulsed EPR techniques is as yet still largely unexploited in the field of oxo-Cr(V) complexes. Subsequently, the discussion focuses on the analysis of oxo-Cr(V) complexes of different types of sugars and the implications of the results in terms of understanding chromium (bio)chemistry.

  19. Structural and mutational studies of an electron transfer complex of maize sulfite reductase and ferredoxin.

    PubMed

    Kim, Ju Yaen; Nakayama, Masato; Toyota, Hiroshi; Kurisu, Genji; Hase, Toshiharu

    2016-08-01

    The structure of the complex of maize sulfite reductase (SiR) and ferredoxin (Fd) has been determined by X-ray crystallography. Co-crystals of the two proteins prepared under different conditions were subjected to the diffraction analysis and three possible structures of the complex were solved. Although topological relationship of SiR and Fd varied in each of the structures, two characteristics common to all structures were found in the pattern of protein-protein interactions and positional arrangements of redox centres; (i) a few negative residues of Fd contact with a narrow area of SiR with positive electrostatic surface potential and (ii) [2Fe-2S] cluster of Fd and [4Fe-4S] cluster of SiR are in a close proximity with the shortest distance around 12 Å. Mutational analysis of a total of seven basic residues of SiR distributed widely at the interface of the complex showed their importance for supporting an efficient Fd-dependent activity and a strong physical binding to Fd. These combined results suggest that the productive electron transfer complex of SiR and Fd could be formed through multiple processes of the electrostatic intermolecular interaction and this implication is discussed in terms of the multi-functionality of Fd in various redox metabolisms.

  20. Fort Collins Science Center Ecosystem Dynamics branch--interdisciplinary research for addressing complex natural resource issues across landscapes and time

    USGS Publications Warehouse

    Bowen, Zachary H.; Melcher, Cynthia P.; Wilson, Juliette T.

    2013-01-01

    The Ecosystem Dynamics Branch of the Fort Collins Science Center offers an interdisciplinary team of talented and creative scientists with expertise in biology, botany, ecology, geology, biogeochemistry, physical sciences, geographic information systems, and remote-sensing, for tackling complex questions about natural resources. As demand for natural resources increases, the issues facing natural resource managers, planners, policy makers, industry, and private landowners are increasing in spatial and temporal scope, often involving entire regions, multiple jurisdictions, and long timeframes. Needs for addressing these issues include (1) a better understanding of biotic and abiotic ecosystem components and their complex interactions; (2) the ability to easily monitor, assess, and visualize the spatially complex movements of animals, plants, water, and elements across highly variable landscapes; and (3) the techniques for accurately predicting both immediate and long-term responses of system components to natural and human-caused change. The overall objectives of our research are to provide the knowledge, tools, and techniques needed by the U.S. Department of the Interior, state agencies, and other stakeholders in their endeavors to meet the demand for natural resources while conserving biodiversity and ecosystem services. Ecosystem Dynamics scientists use field and laboratory research, data assimilation, and ecological modeling to understand ecosystem patterns, trends, and mechanistic processes. This information is used to predict the outcomes of changes imposed on species, habitats, landscapes, and climate across spatiotemporal scales. The products we develop include conceptual models to illustrate system structure and processes; regional baseline and integrated assessments; predictive spatial and mathematical models; literature syntheses; and frameworks or protocols for improved ecosystem monitoring, adaptive management, and program evaluation. The descriptions